The document discusses the four levels of protein structure: primary, secondary, tertiary, and quaternary. It explains that proteins are made of amino acids that are linked together via peptide bonds. The order and sequence of amino acids determines the primary structure. Hydrogen bonding leads to the formation of regular structures like alpha helices and beta sheets, which make up the secondary structure. Tertiary structure refers to the overall three-dimensional shape of the protein, which is stabilized by interactions between amino acid side chains. Some proteins have quaternary structure consisting of multiple polypeptide subunits.
Proteins are made up of elements like carbon, hydrogen, oxygen, nitrogen, sulfur, and phosphorus. They are formed through condensation reactions between amino acids and can be broken down through hydrolysis. There are four levels of protein structure: primary, secondary, tertiary, and quaternary. The primary structure is the linear sequence of amino acids, secondary structure involves alpha helices and beta sheets, tertiary is the overall 3D shape, and quaternary involves combinations of tertiary structures. There are essential and non-essential amino acids, with essential ones not synthesized by the body.
Proteins are made up of chains of amino acids that form various structures which determine the protein's function. The amino acid sequence forms the primary structure. Hydrogen bonding forms regular patterns of alpha helices and beta sheets as the secondary structure. Tertiary structure is the final 3D shape from hydrophobic interactions. Some proteins have quaternary structure as complexes of multiple polypeptide chains.
This document discusses amino acids and proteins. It begins by defining proteins as polymers of amino acids and describing the basic structure of amino acids. It then covers the different configurations of amino acids, their properties in aqueous solutions, and classifications. The document also discusses the structures of peptides and proteins at the primary, secondary, tertiary, and quaternary levels. It describes the digestion and metabolism of amino acids as well as the urea cycle. Finally, it provides an overview of protein biosynthesis, including the roles of DNA, mRNA, tRNA, and ribosomes.
Food proteins can be obtained from both animal and plant sources. The document discusses the physicochemical properties of proteins including their amino acid composition, classification, ionization behavior, and structure. It also covers the various levels of protein structure from primary to quaternary. The main sources of protein discussed include soybean products, cottonseed flour, mycoprotein, leaf protein concentrate, and microbial biomass protein.
Proteins have a variety of important functions in living organisms. They are made up of chains of amino acids that join together to form complex structures ranging from simple primary to advanced quaternary structures which determine their specific roles. Globular proteins have spherical shapes defined by their amino acid sequences which allow metabolic functions like enzymatic reactions, while changes in structure through denaturation disrupt protein functioning.
The document discusses several key biological molecules including amino acids, proteins, DNA and RNA. It provides information on their structures and functions. Specifically, it explains that amino acids combine to form proteins, and that DNA and RNA are made up of nucleotides that contain nitrogenous bases and form structures through hydrogen bonding. The roles of these molecules in processes like protein synthesis and gene expression are also summarized.
Proteins are polymers of amino acids linked by peptide bonds. Amino acids contain an amino group, a carboxyl group, and a side chain that differs between the 20 standard amino acids. Proteins are made through peptide bond formation between amino acid residues. They have many functions including building body structures, catalyzing biochemical reactions, transporting molecules, responding to stimuli, and providing nutrition. Proteins can undergo denaturation where their tertiary and quaternary structures are lost, though the peptide bonds remain intact. Denaturation involves the unfolding and disorganization of a protein and can be caused by heat, chemicals, or other stressors.
The document provides information on proteins, including:
- Proteins are the most abundant organic molecules and constitute about 50% of cellular dry weight. They perform structural and dynamic functions in the cell.
- Proteins are polymers of amino acids. There are 20 standard amino acids that make up proteins. Amino acids contain amino and carboxyl groups and have varying side chains that determine their properties.
- The primary structure of a protein is its unique sequence of amino acids as determined by genes. Higher levels of structure include secondary, tertiary and quaternary organization that influence a protein's shape and function.
Proteins are made up of elements like carbon, hydrogen, oxygen, nitrogen, sulfur, and phosphorus. They are formed through condensation reactions between amino acids and can be broken down through hydrolysis. There are four levels of protein structure: primary, secondary, tertiary, and quaternary. The primary structure is the linear sequence of amino acids, secondary structure involves alpha helices and beta sheets, tertiary is the overall 3D shape, and quaternary involves combinations of tertiary structures. There are essential and non-essential amino acids, with essential ones not synthesized by the body.
Proteins are made up of chains of amino acids that form various structures which determine the protein's function. The amino acid sequence forms the primary structure. Hydrogen bonding forms regular patterns of alpha helices and beta sheets as the secondary structure. Tertiary structure is the final 3D shape from hydrophobic interactions. Some proteins have quaternary structure as complexes of multiple polypeptide chains.
This document discusses amino acids and proteins. It begins by defining proteins as polymers of amino acids and describing the basic structure of amino acids. It then covers the different configurations of amino acids, their properties in aqueous solutions, and classifications. The document also discusses the structures of peptides and proteins at the primary, secondary, tertiary, and quaternary levels. It describes the digestion and metabolism of amino acids as well as the urea cycle. Finally, it provides an overview of protein biosynthesis, including the roles of DNA, mRNA, tRNA, and ribosomes.
Food proteins can be obtained from both animal and plant sources. The document discusses the physicochemical properties of proteins including their amino acid composition, classification, ionization behavior, and structure. It also covers the various levels of protein structure from primary to quaternary. The main sources of protein discussed include soybean products, cottonseed flour, mycoprotein, leaf protein concentrate, and microbial biomass protein.
Proteins have a variety of important functions in living organisms. They are made up of chains of amino acids that join together to form complex structures ranging from simple primary to advanced quaternary structures which determine their specific roles. Globular proteins have spherical shapes defined by their amino acid sequences which allow metabolic functions like enzymatic reactions, while changes in structure through denaturation disrupt protein functioning.
The document discusses several key biological molecules including amino acids, proteins, DNA and RNA. It provides information on their structures and functions. Specifically, it explains that amino acids combine to form proteins, and that DNA and RNA are made up of nucleotides that contain nitrogenous bases and form structures through hydrogen bonding. The roles of these molecules in processes like protein synthesis and gene expression are also summarized.
Proteins are polymers of amino acids linked by peptide bonds. Amino acids contain an amino group, a carboxyl group, and a side chain that differs between the 20 standard amino acids. Proteins are made through peptide bond formation between amino acid residues. They have many functions including building body structures, catalyzing biochemical reactions, transporting molecules, responding to stimuli, and providing nutrition. Proteins can undergo denaturation where their tertiary and quaternary structures are lost, though the peptide bonds remain intact. Denaturation involves the unfolding and disorganization of a protein and can be caused by heat, chemicals, or other stressors.
The document provides information on proteins, including:
- Proteins are the most abundant organic molecules and constitute about 50% of cellular dry weight. They perform structural and dynamic functions in the cell.
- Proteins are polymers of amino acids. There are 20 standard amino acids that make up proteins. Amino acids contain amino and carboxyl groups and have varying side chains that determine their properties.
- The primary structure of a protein is its unique sequence of amino acids as determined by genes. Higher levels of structure include secondary, tertiary and quaternary organization that influence a protein's shape and function.
Amino acids, Structure of Protein and Amino acid metabolism Pramod Pandey
This document provides an overview of amino acids and protein structure and metabolism. It begins with definitions of amino acid structure and classifications based on properties. It then discusses protein structure at the primary, secondary, tertiary and quaternary levels. Key metabolic pathways of amino acids are covered, including transamination, deamination, the urea cycle, and the metabolism of specific amino acids like glycine, phenylalanine, tyrosine, and tryptophan.
Proteins are polymers of amino acids and have a primary, secondary, tertiary, and sometimes quaternary structure that determines their function. There are 20 common amino acids which differ in their side chains and properties like polarity. Amino acids join through peptide bonds to form proteins. Denaturation disrupts the structure of proteins above the primary level through breaking of non-covalent bonds, causing a loss of biological activity.
Proteins are composed of chains of amino acids and serve important structural and functional roles in biology. They can be classified based on their composition, structure, and biological function. Common analytical techniques used to study proteins include chromatography, electrophoresis, and mass spectrometry which separate proteins based on properties like size and charge. The diversity of amino acid side chains allows proteins to adopt complex 3D structures and perform a wide variety of critical roles in the body.
Proteins are the most abundant and functionally diverse molecules in living systems, composed of amino acids linked by peptide bonds. They can be classified in various ways, including by molecular structure (globular vs fibrous), solubility, presence of non-protein groups, function (enzymes, hormones, etc.), and nutritional quality. The 20 primary amino acids are the building blocks of all proteins in plants and animals, and each has a specific genetic codon in mRNA.
This document discusses proteins and their structure. It begins by introducing proteins and their composition of amino acids linked into peptide chains. It then describes the 20 main amino acids and how they are classified. The four levels of protein structural organization - primary, secondary, tertiary, and quaternary structure - are outlined. Common secondary structures like the alpha helix and beta sheet are also defined. Specific proteins like hemoglobin and myoglobin are then examined in more detail, including their subunit composition and role in oxygen transport.
Proteins have four levels of structural organization: primary, secondary, tertiary, and quaternary. The primary structure refers to the linear sequence of amino acids in the polypeptide chain. Secondary structure involves local folding patterns like alpha helices and beta sheets. Tertiary structure describes the overall 3D shape of a single polypeptide chain. Quaternary structure is the 3D structure formed by the assembly of multiple polypeptide subunits. The structures at each level are stabilized by interactions between the R groups of amino acids in the chain.
This document provides an introduction and overview of protein structure and classification. It discusses the basic building blocks of proteins, the four levels of protein structure (primary, secondary, tertiary, and quaternary), and two main methods of protein classification - by shape (globular vs. fibrous proteins) and by function (enzymes, hormones, structural proteins, etc.). The document aims to cover key concepts about protein structure and organization in a comprehensive yet concise manner.
Amino acids are organic compounds containing amino and carboxylic acid groups. There are about 300 amino acids in nature but only 20 are found in proteins. Amino acids are linked together via peptide bonds to form polypeptide chains and proteins. There are four levels of protein structure - primary, secondary, tertiary, and quaternary - that determine a protein's shape and function. Proteins can be classified as simple proteins which break down into amino acids, or conjugated proteins which break down into a protein and non-protein component like lipids or carbohydrates.
AN INTRODUCTION TO PROTEIN AND AMINO ACIDS. CLASSIFICATION OF AMINO ACIDS AND PROTEINS IS GIVEN. PRIMARY, SECONDARY,TERTIARY AND QUATERNERY STRUCTURES OF PROTEINS IS DISCUSSED. DIFFERENT TYPES OF BONDS PRESENT IN PROTEINS IS DISCUSSED.
This document discusses the structure and functions of amino acids. It begins by explaining that amino acids serve as the building blocks of proteins and play central roles in metabolism. The 20 amino acids that make up proteins convey a vast array of chemical versatility. The specific amino acid sequence of a protein determines its biological activity and three-dimensional structure. Amino acids are then classified based on their chemical structure, polarity, and nutritional value. The document outlines that amino acids can be essential, semi-essential, or non-essential depending on whether the human body can synthesize them. In summary, this document provides an overview of the key roles and classifications of the 20 amino acids that make up proteins in the human body.
Amino acids are the building blocks of proteins. They contain both acidic and basic groups that allow them to polymerize and form peptide bonds, assembling into linear chains known as polypeptides or proteins. There are 20 common amino acids that make up proteins, which can be classified based on their variable R groups into nonpolar, aromatic, polar uncharged, positively charged, and negatively charged categories. Proteins perform a wide variety of important biological functions in the body as enzymes, structural components, binding proteins, hormones, and more.
Proteins are composed of amino acids and have four levels of structure: primary, secondary, tertiary, and quaternary. The primary structure is the linear sequence of amino acids. Secondary structure involves local folding into patterns like alpha helices and beta sheets. Tertiary structure is the overall three-dimensional shape formed by interactions between different parts of the polypeptide chain. Quaternary structure refers to the shape of proteins with multiple polypeptide subunits. Proteins perform many important functions in the body as enzymes, antibodies, hormones, and structural components.
Proteins and its classification in details by @sushant junejasushantjuneja1
This document is a chemistry project report submitted by Sushant Juneja, a 12th grade student, to his teacher Mrs. Inderpreet Sujlana. The project is about proteins and includes an introduction, sections on amino acids, protein structure, classification of proteins, isoelectric pH, and protein denaturation. It provides details on the various levels of protein structure from primary to quaternary structure. It also classifies proteins based on function and shape.
The document discusses proteins, including their structure, functions, and importance. It defines proteins as polymers of amino acids. There are 20 different amino acids that make up proteins. Amino acids are linked together via peptide bonds to form polypeptide chains, which then fold into complex protein structures like the primary, secondary, tertiary, and quaternary levels. Proteins serve important roles in the body such as structure, storage, transport, hormones, receptors, movement, defense, and catalysis. They are essential biomolecules found in living cells.
Some reagents or conditions that can cause protein denaturation include:
- High or low pH (acids and bases)
- Heat
- Detergents
- Organic solvents (alcohol, acetone)
- Heavy metals (salts of heavy metals like copper, mercury)
- Radiation (UV light, X-rays)
Biochemistry Biochemistry and clinical pathology -NOTEStwilight89
This document provides information about proteins and their classification with examples. It discusses simple proteins like albumins and globulins, conjugated proteins including lipoproteins, nucleoproteins, metalloproteins, and phosphoproteins. It also mentions derived proteins and their primary and secondary derivatives. The document contains short questions and answers on various topics in biochemistry including the biological functions of minerals, essential amino acids, the urea cycle, enzymes, carbohydrates, and their diagnostic and therapeutic applications.
Proteins have four levels of structure: primary, secondary, tertiary, and quaternary. The primary structure is the sequence of amino acids in the polypeptide chain. Secondary structure involves hydrogen bonding that forms alpha helices and beta pleats. Tertiary structure is the folding of the polypeptide chain, influenced by properties of amino acids, to form domains. Quaternary structure occurs when multiple polypeptide subunits combine to form the functional protein structure. Protein structure determines its function, as denaturation can change structure and function.
Proteins are composed of amino acids that link together via peptide bonds. There are 20 naturally occurring amino acids that vary in properties like polarity, charge, and ability to form secondary structures. The sequence and interactions of amino acids give proteins their unique 3D structures and functions. Denaturation disrupts non-covalent bonds within proteins, altering their shapes and eliminating biological activity.
This document discusses the classification and structure of proteins. It describes the four levels of protein structure: primary, secondary, tertiary, and quaternary. The primary structure is the linear sequence of amino acids. The secondary structure involves local folding patterns stabilized by hydrogen bonds. The tertiary structure is the overall three-dimensional shape of a protein determined by interactions between amino acid side chains. Quaternary structure refers to the arrangement of multiple protein subunits. The document also categorizes proteins based on their biological functions and physical properties.
Dystrophin is a high molecular weight cytoskeletal protein that localizes to the cytoplasmic face of the sarcolemma. It has four domains - an actin binding domain, a central rod domain composed of spectrin-like repeats, a cysteine-rich domain, and a carboxy-terminal domain. Dystrophin forms the dystrophin-glycoprotein complex with other proteins like dystroglycans and sarcoglycans to connect the actin cytoskeleton to the extracellular matrix. Mutations in dystrophin cause Duchenne/Becker muscular dystrophy by disrupting this connection and leading to muscle degeneration.
Protein structure is hierarchical, proceeding from primary to quaternary structure. Primary structure refers to the linear sequence of amino acids. Secondary structure involves folding into alpha helices and beta sheets. Tertiary structure describes the overall three-dimensional shape of a polypeptide. Quaternary structure refers to the arrangement of multiple protein subunits. Several methods can determine protein structure at high resolution, including X-ray crystallography, NMR spectroscopy, cryo-electron microscopy, and X-ray free electron lasers.
Proteins are the most abundant organic molecules in living systems, making up about 50% of cellular dry weight. They occur throughout the cell and form the basic structure and functions of life. All proteins are polymers of amino acids. There are four levels of protein structure: primary, secondary, tertiary, and quaternary. The primary structure is the linear sequence of amino acids joined by peptide bonds. Secondary structure involves hydrogen bonding that causes regions of the polypeptide chain to fold into alpha helices or beta sheets. Tertiary structure describes the three-dimensional shape that proteins fold into. Quaternary structure refers to complexes of multiple polypeptide subunits.
Amino acids, Structure of Protein and Amino acid metabolism Pramod Pandey
This document provides an overview of amino acids and protein structure and metabolism. It begins with definitions of amino acid structure and classifications based on properties. It then discusses protein structure at the primary, secondary, tertiary and quaternary levels. Key metabolic pathways of amino acids are covered, including transamination, deamination, the urea cycle, and the metabolism of specific amino acids like glycine, phenylalanine, tyrosine, and tryptophan.
Proteins are polymers of amino acids and have a primary, secondary, tertiary, and sometimes quaternary structure that determines their function. There are 20 common amino acids which differ in their side chains and properties like polarity. Amino acids join through peptide bonds to form proteins. Denaturation disrupts the structure of proteins above the primary level through breaking of non-covalent bonds, causing a loss of biological activity.
Proteins are composed of chains of amino acids and serve important structural and functional roles in biology. They can be classified based on their composition, structure, and biological function. Common analytical techniques used to study proteins include chromatography, electrophoresis, and mass spectrometry which separate proteins based on properties like size and charge. The diversity of amino acid side chains allows proteins to adopt complex 3D structures and perform a wide variety of critical roles in the body.
Proteins are the most abundant and functionally diverse molecules in living systems, composed of amino acids linked by peptide bonds. They can be classified in various ways, including by molecular structure (globular vs fibrous), solubility, presence of non-protein groups, function (enzymes, hormones, etc.), and nutritional quality. The 20 primary amino acids are the building blocks of all proteins in plants and animals, and each has a specific genetic codon in mRNA.
This document discusses proteins and their structure. It begins by introducing proteins and their composition of amino acids linked into peptide chains. It then describes the 20 main amino acids and how they are classified. The four levels of protein structural organization - primary, secondary, tertiary, and quaternary structure - are outlined. Common secondary structures like the alpha helix and beta sheet are also defined. Specific proteins like hemoglobin and myoglobin are then examined in more detail, including their subunit composition and role in oxygen transport.
Proteins have four levels of structural organization: primary, secondary, tertiary, and quaternary. The primary structure refers to the linear sequence of amino acids in the polypeptide chain. Secondary structure involves local folding patterns like alpha helices and beta sheets. Tertiary structure describes the overall 3D shape of a single polypeptide chain. Quaternary structure is the 3D structure formed by the assembly of multiple polypeptide subunits. The structures at each level are stabilized by interactions between the R groups of amino acids in the chain.
This document provides an introduction and overview of protein structure and classification. It discusses the basic building blocks of proteins, the four levels of protein structure (primary, secondary, tertiary, and quaternary), and two main methods of protein classification - by shape (globular vs. fibrous proteins) and by function (enzymes, hormones, structural proteins, etc.). The document aims to cover key concepts about protein structure and organization in a comprehensive yet concise manner.
Amino acids are organic compounds containing amino and carboxylic acid groups. There are about 300 amino acids in nature but only 20 are found in proteins. Amino acids are linked together via peptide bonds to form polypeptide chains and proteins. There are four levels of protein structure - primary, secondary, tertiary, and quaternary - that determine a protein's shape and function. Proteins can be classified as simple proteins which break down into amino acids, or conjugated proteins which break down into a protein and non-protein component like lipids or carbohydrates.
AN INTRODUCTION TO PROTEIN AND AMINO ACIDS. CLASSIFICATION OF AMINO ACIDS AND PROTEINS IS GIVEN. PRIMARY, SECONDARY,TERTIARY AND QUATERNERY STRUCTURES OF PROTEINS IS DISCUSSED. DIFFERENT TYPES OF BONDS PRESENT IN PROTEINS IS DISCUSSED.
This document discusses the structure and functions of amino acids. It begins by explaining that amino acids serve as the building blocks of proteins and play central roles in metabolism. The 20 amino acids that make up proteins convey a vast array of chemical versatility. The specific amino acid sequence of a protein determines its biological activity and three-dimensional structure. Amino acids are then classified based on their chemical structure, polarity, and nutritional value. The document outlines that amino acids can be essential, semi-essential, or non-essential depending on whether the human body can synthesize them. In summary, this document provides an overview of the key roles and classifications of the 20 amino acids that make up proteins in the human body.
Amino acids are the building blocks of proteins. They contain both acidic and basic groups that allow them to polymerize and form peptide bonds, assembling into linear chains known as polypeptides or proteins. There are 20 common amino acids that make up proteins, which can be classified based on their variable R groups into nonpolar, aromatic, polar uncharged, positively charged, and negatively charged categories. Proteins perform a wide variety of important biological functions in the body as enzymes, structural components, binding proteins, hormones, and more.
Proteins are composed of amino acids and have four levels of structure: primary, secondary, tertiary, and quaternary. The primary structure is the linear sequence of amino acids. Secondary structure involves local folding into patterns like alpha helices and beta sheets. Tertiary structure is the overall three-dimensional shape formed by interactions between different parts of the polypeptide chain. Quaternary structure refers to the shape of proteins with multiple polypeptide subunits. Proteins perform many important functions in the body as enzymes, antibodies, hormones, and structural components.
Proteins and its classification in details by @sushant junejasushantjuneja1
This document is a chemistry project report submitted by Sushant Juneja, a 12th grade student, to his teacher Mrs. Inderpreet Sujlana. The project is about proteins and includes an introduction, sections on amino acids, protein structure, classification of proteins, isoelectric pH, and protein denaturation. It provides details on the various levels of protein structure from primary to quaternary structure. It also classifies proteins based on function and shape.
The document discusses proteins, including their structure, functions, and importance. It defines proteins as polymers of amino acids. There are 20 different amino acids that make up proteins. Amino acids are linked together via peptide bonds to form polypeptide chains, which then fold into complex protein structures like the primary, secondary, tertiary, and quaternary levels. Proteins serve important roles in the body such as structure, storage, transport, hormones, receptors, movement, defense, and catalysis. They are essential biomolecules found in living cells.
Some reagents or conditions that can cause protein denaturation include:
- High or low pH (acids and bases)
- Heat
- Detergents
- Organic solvents (alcohol, acetone)
- Heavy metals (salts of heavy metals like copper, mercury)
- Radiation (UV light, X-rays)
Biochemistry Biochemistry and clinical pathology -NOTEStwilight89
This document provides information about proteins and their classification with examples. It discusses simple proteins like albumins and globulins, conjugated proteins including lipoproteins, nucleoproteins, metalloproteins, and phosphoproteins. It also mentions derived proteins and their primary and secondary derivatives. The document contains short questions and answers on various topics in biochemistry including the biological functions of minerals, essential amino acids, the urea cycle, enzymes, carbohydrates, and their diagnostic and therapeutic applications.
Proteins have four levels of structure: primary, secondary, tertiary, and quaternary. The primary structure is the sequence of amino acids in the polypeptide chain. Secondary structure involves hydrogen bonding that forms alpha helices and beta pleats. Tertiary structure is the folding of the polypeptide chain, influenced by properties of amino acids, to form domains. Quaternary structure occurs when multiple polypeptide subunits combine to form the functional protein structure. Protein structure determines its function, as denaturation can change structure and function.
Proteins are composed of amino acids that link together via peptide bonds. There are 20 naturally occurring amino acids that vary in properties like polarity, charge, and ability to form secondary structures. The sequence and interactions of amino acids give proteins their unique 3D structures and functions. Denaturation disrupts non-covalent bonds within proteins, altering their shapes and eliminating biological activity.
This document discusses the classification and structure of proteins. It describes the four levels of protein structure: primary, secondary, tertiary, and quaternary. The primary structure is the linear sequence of amino acids. The secondary structure involves local folding patterns stabilized by hydrogen bonds. The tertiary structure is the overall three-dimensional shape of a protein determined by interactions between amino acid side chains. Quaternary structure refers to the arrangement of multiple protein subunits. The document also categorizes proteins based on their biological functions and physical properties.
Dystrophin is a high molecular weight cytoskeletal protein that localizes to the cytoplasmic face of the sarcolemma. It has four domains - an actin binding domain, a central rod domain composed of spectrin-like repeats, a cysteine-rich domain, and a carboxy-terminal domain. Dystrophin forms the dystrophin-glycoprotein complex with other proteins like dystroglycans and sarcoglycans to connect the actin cytoskeleton to the extracellular matrix. Mutations in dystrophin cause Duchenne/Becker muscular dystrophy by disrupting this connection and leading to muscle degeneration.
Protein structure is hierarchical, proceeding from primary to quaternary structure. Primary structure refers to the linear sequence of amino acids. Secondary structure involves folding into alpha helices and beta sheets. Tertiary structure describes the overall three-dimensional shape of a polypeptide. Quaternary structure refers to the arrangement of multiple protein subunits. Several methods can determine protein structure at high resolution, including X-ray crystallography, NMR spectroscopy, cryo-electron microscopy, and X-ray free electron lasers.
Proteins are the most abundant organic molecules in living systems, making up about 50% of cellular dry weight. They occur throughout the cell and form the basic structure and functions of life. All proteins are polymers of amino acids. There are four levels of protein structure: primary, secondary, tertiary, and quaternary. The primary structure is the linear sequence of amino acids joined by peptide bonds. Secondary structure involves hydrogen bonding that causes regions of the polypeptide chain to fold into alpha helices or beta sheets. Tertiary structure describes the three-dimensional shape that proteins fold into. Quaternary structure refers to complexes of multiple polypeptide subunits.
Proteins play key roles in living systems through catalysis, transport, and information transfer. They have a hierarchical structure including primary, secondary, tertiary, and quaternary levels. The primary structure is the amino acid sequence, and higher levels of organization are determined by the primary structure. Protein folding and interactions between residues determine the final 3D tertiary and quaternary structures, which are critical for protein function. Misfolded proteins can cause diseases.
levels of protein structure , Domains ,motifs & Folds in protein structureAaqib Naseer
Protein structure is hierarchical, with four levels: primary, secondary, tertiary, and quaternary. The primary structure is the amino acid sequence. Secondary structures include alpha helices and beta sheets formed by hydrogen bonding between amino acids in the sequence. Tertiary structure involves folding of the entire chain into a compact 3D structure. Quaternary structure involves the assembly of protein subunits. Other structural features include domains, which are independently folded and functional regions, motifs like loops and barrels formed by secondary structure elements, and folds defined by the arrangement of alpha helices and beta sheets. Understanding protein structure is important for studying protein function and for developing drugs.
This document discusses amino acids and proteins. It begins by defining proteins as being formed from amino acids, which are the monomers or building blocks of proteins. The document then covers the structure of amino acids, including their general formula and configurations. It also discusses the properties of amino acids in aqueous solutions and their classification as essential or non-essential. The document goes on to explain how amino acids can bond together to form peptides and polypeptides, and the levels of protein structure from primary to quaternary. It concludes with sections on the metabolism of proteins and amino acids in the body.
Introduction:
Protein
Protein motif.
2. History:
3. A brief overview of protein structure.
4. The Structural Classification of Protein(SCOP):
All α.
All β
α/β
α+β
5.The super secondary structure.
6. Rules for formation of Protein Motifs.
7. Structural motifs.
8. Some Common Protein Motifs:
β-hairpin.
β-meander.
Alpha-alpha corner.
Helix-turn-helix motif.
β-α-β motif.
β-sandwich.
β-barrel.
Greek key.
The Jellyroll topology.
Omega loop.
Zinc finger motif.
9. Conclusion.
10. References.
- The document discusses protein metabolism and nitrogen fixation. It covers the classification of proteins based on their structure, composition, and functions. There are four levels of protein structure - primary, secondary, tertiary, and quaternary.
- The primary structure is the linear sequence of amino acids. The secondary structure involves folding into alpha helices or beta sheets via hydrogen bonding. Tertiary structure describes the overall 3D shape formed by interactions between amino acid R groups. Quaternary structure applies to proteins with multiple polypeptide chains that combine to form complexes.
- Proteins are classified as globular, fibrous, or intermediate based on their shape. They can also be simple or conjugated based on composition
Proteins are polymers made up of amino acid chains that form specific structures. There are four levels of protein structure:
1. Primary structure is the amino acid sequence.
2. Secondary structures include alpha helices and beta sheets formed by hydrogen bonds between amino acids.
3. Tertiary structure is the three dimensional folding of secondary structures.
4. Quaternary structure occurs in proteins made of multiple polypeptide chains that aggregate. The document discusses these levels of structure in detail, focusing on alpha helices and beta sheets as common secondary structures stabilized by hydrogen bonding.
The document discusses the structure of proteins at various levels of organization:
- Proteins are composed of amino acids linked together by peptide bonds to form polypeptide chains. The sequence and interactions of these chains determine the protein's structure.
- There are four levels of protein structure - primary, secondary, tertiary, and quaternary. Secondary structure includes alpha helices and beta sheets formed by hydrogen bonding between amino acids in the chain. Tertiary structure describes the overall 3D shape formed by interactions between amino acid side chains. Quaternary structure involves the interaction of multiple polypeptide chains.
- Protein structure enables proteins to perform their diverse functions through processes like enzyme catalysis, oxygen transport, and providing structure
This document provides an overview of protein structure, including levels of structure and classification. It discusses the importance of protein structure in determining function. The primary levels of structure are defined as primary (amino acid sequence), secondary (local folding patterns like alpha helices and beta sheets), tertiary (packing of secondary structures), and quaternary (assembly of protein chains). Protein structures can be classified based on their secondary structure composition as all-alpha, all-beta, alpha/beta, or alpha+beta. Domains are compact folding units associated with function.
Proteins have a defined primary, secondary, tertiary, and quaternary structure that determines their function. The primary structure is the linear sequence of amino acids in a polypeptide chain. Secondary structures form due to hydrogen bonding and include alpha helices and beta pleated sheets. Tertiary structure is influenced by interactions between amino acid side chains that cause the polypeptide to fold into a compact 3D shape. Quaternary structure occurs when multiple polypeptide chains assemble together, as seen in hemoglobin which has four polypeptide subunits. Protein structure can be disrupted by denaturation through heat, acids, bases, salts, or solvents breaking bonds like hydrogen and ionic bonds.
Proteins are made up of amino acids joined together in chains that fold up into complex three-dimensional shapes determined by their primary, secondary, tertiary, and sometimes quaternary structure. There are 20 different amino acids that can be arranged in primary structures and then fold into secondary structures like alpha helices and beta sheets driven by hydrogen bonding. Tertiary structure describes how the whole chain folds into its final 3D shape through interactions between amino acid side chains. Some proteins have quaternary structure involving clustering of multiple chains.
The document discusses the four levels of protein structure: primary, secondary, tertiary, and quaternary. It provides examples of common secondary structures like alpha helices and beta sheets. Tertiary structure describes the 3D arrangement of all atoms in the protein. Quaternary structure refers to the association of multiple polypeptide chains. The document outlines various experimental techniques used to determine protein structure like X-ray crystallography and NMR.
This document provides an overview of protein structure and classification. It discusses the four levels of protein structure: primary, secondary, tertiary, and quaternary. The primary structure is the linear sequence of amino acids in the polypeptide chain. Secondary structure forms from recurring patterns like alpha helices and beta sheets, stabilized by hydrogen bonds. Tertiary structure involves the overall three-dimensional shape of the protein formed from interactions between different secondary structure elements. Quaternary structure refers to the shape of proteins with multiple polypeptide subunits. The document also outlines various ways proteins can be classified and their important functions.
Proteins are organic compounds made of amino acids that are vital to living cells. They perform important functions like structure, protection, transport of substances, and catalyzing reactions. There are four levels of protein structure - primary, secondary, tertiary, and quaternary. The primary structure is the specific sequence of amino acids in the protein chain. Secondary structure involves bonds between amino acids close in sequence, forming structures like alpha helices and beta sheets. Tertiary structure describes the 3D structure of the whole protein formed by interactions between distant amino acids. Quaternary structure refers to proteins made of multiple polypeptide subunits that interact to form a functional complex.
Proteins are polymers of amino acids linked by peptide bonds that fold into complex three-dimensional structures essential for their functions. There are four levels of protein structure: primary structure is the amino acid sequence; secondary structures include alpha helices and beta sheets formed by hydrogen bonds between amino acids in the backbone. Tertiary structure describes the overall three-dimensional shape including side chains, while quaternary structure refers to the arrangement of multiple protein subunits. The amino acid sequence ultimately determines the three-dimensional structure which is critical for a protein's function.
This document provides an overview of protein structure and function. It discusses the central dogma of life, the four levels of protein structure (primary, secondary, tertiary, and quaternary), common secondary structures like alpha helices and beta sheets, protein folding, domains, and important experiments like Anfinsen's that demonstrated proteins can fold on their own. It also mentions applications of protein structure knowledge like structure-based drug design and solving medical problems like sickle cell anemia.
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Pengetahuan struktur, bentuk dan sintesa protein
1.
2. Building blocks of proteins are called Amino Acids.
All proteins contain the elements Carbon, Hydrogen,
Oxygen and Nitrogen.
Amino Acids contain the -NH2 group which is called the amino
group
And the COOH group or the Carboxyl group.
Amino Acids are defined by the side group or R-Group.
3. The bond that holds
amino acids together is
called a peptide bond.
When two more amino
acids are put together
they become a
polypeptide.
The order in which amino acids are placed in the chain
determines the structure of the protein.
The structure of the protein determines
the function of the protein.
4. From amino acids to protein:
N-terminus
terminates
by an amino group
Peptide bond
Amino acid
C-terminus
terminates by a
carboxyl group
A peptide: Phe-Ser-Glu-Lys (F-S-E-K)
5. The Shape of proteins:
Occurs
Spontaneously
Native conformation
determined by different
Levels of structure
7. Four Levels of Structure Determine the
Shape of Proteins
Primary structure
The linear arrangement (sequence) of amino acids and the location of covalent (mostly
disulfide) bonds within a polypeptide chain. Determined by the genetic code.
Secondary structure
local folding of a polypeptide chain into regular structures including the helix,
sheet, and U-shaped turns and loops.
Tertiary structure
overall three-dimensional form of a polypeptide chain, which is stabilized by multiple
non-covalent interactions between side chains.
Quaternary structure:
The number and relative positions of the polypeptide chains in multisubunit
proteins. Not all protein have a quaternary structure.
8. Primary Structure Pro-insulin is
produced in the
C-peptide Pancreatic islet cells
Pro-insulin protein
65/66 30/31
Human: Thr-Ser-Ile
Cow: Ala-Ser-Val
Pig: Thr-Ser-Ile
Chiken: His-Asn-Thr
Insuline
C-peptide
+ C peptide
9. Protein conformation: most of the proteins fold
into only one stable conformation or native
conformation
More than 50 amino acids becomes a protein
10. Protein conformation: most of the proteins fold
into only one stable conformation or native
conformation
More than 50 amino acids becomes a protein
11. SECONDARY STRUCTURE
Stabilized by hydrogen bonds
H- bonds are between –CO and –NH groups of
peptide backbone
H-bonds are either intra- or inter- molecular
3 types : a-helix, b-sheet and triple-helix
Helix:
helix conformation was discovered 50 years ago in keratine
abundant in hair nails, and horns
Sheet:
discovered within a year of the discovery of helix. Found in
protein fibroin the major constituant of silk
12. The helix:
result from hydrogen bonding, does not involve the side chain of the amino
acid
14. Two type of
Sheet structures
An anti paralellel
sheet
A paralellel
sheet
15. TRIPLE HELIX
Limited to tropocollagen molecule
Sequence motif of –(Gly-X-Pro/Hypro)n-
3 left-handed helices wound together to give a
right-handed superhelix
Stable superhelix : glycines located on the
central axis (small R group) of triple helix
One interchain H-bond for each triplet of aas
– between NH of Gly and CO of X (or Proline)
in the adjacent chain
Triple helix of Collagen
16. NONREPETITIVE STRUCTURES
Helices/ -sheets: ~50% of regular
2ostructures of globular proteins
Remaining : coil or loop conformation
Also quite regular, but difficult to describe
Examples : reverse turns, -bends
(connect successive strands of antiparallel
-sheets)
17. The Beta Turn
(aka beta bend, tight turn)
allows the peptide chain to reverse direction
carbonyl O of one residue is H-bonded to the amide proton of a residue
three residues away
proline and glycine are prevalent in beta turns (?)
18. -bulge
A strand of polypeptide in a -sheet may contain an “extra” residue
This extra residue is not hydrogen bonded to a neighbouring strand
This is known as a -bulge.
19. Tertiary structure: the overall shape of a protein
The secondary structure of a telephone
cord
A telephone cord, specifically the coil of a
telephone cord, can be used as an analogy
to the alpha helix secondary structure of a
protein.
The tertiary structure of a telephone cord
The tertiary structure of a protein refers to the
way the secondary structure folds back upon
itself or twists around to form a three-
dimensional structure. The secondary coil
structure is still there, but the tertiary tangle has
been superimposed on it.
20. Tertiary structure: the overall shape of a protein
Full three dimensional organization of a protein
R-group interactions result in 3D
structures of globular proteins
Types of interactions : H-, ionic-
(salt linkage), hydrophobic- and
disulphide- bond
Hydrophilic R groups on surface
while hydrophobic R groups
buried inside of molecule
Wide variety of 3o structures:
since large variation in protein
sizes and amino acid sequences
The three-dimensional structure of a protein kinase
21. The role of side chain in the shape of proteins
Hydrophili
c
Hydrophobic
22.
23. A coiled-coil:
Structure occurs when the 2 a
helix have most of their nonpolar
(hydrophobic) side chains on one
side, so that they can twist around
each other with these side chain
facing inwards
24. Quaternery
structure:
If protein is formed as a
complex of more than one
protein chain, the complete
structure is designed as
quaternery structure:
• Generally formed by non-
covalent interactions
between subunits
• Either as homo- or
hetero-multimers
25. QUATERNARY STRUCTURE:
ADVANTAGES
Oligomers (multimers) are more stable than
dissociated subunits
They prolong life of protein in vivo
Active sites can be formed by residues from adjacent
subunits/chains
A subunit may not constitute a complete active site
Error of synthesis is greater for longer polypeptide
chains
Subunit interactions : cooperativity/ allosteric effects
27. Protein domains:
•Any part of a protein that can fold
independently into a compact, stable
structure. A domain usually contains between
40 and 350 amino acids.
• A domain is the modular unit from which
many larger proteins are constructed.
• The different domain of protein are often
associated with different functions.
28. Protein domains
The NAD-binding
Cytochrome b562 domain of
A single domain protein the enzyme lactic
dehydrogenase The variable domain
involved in electron transport
of an immunoglobulin
in mitochondria
29. Protein Folding
is the physical process by which a polypeptide folds into its characteristic and
functional three-dimensional structure from random coil.[1] Each protein exists as
an unfolded polypeptide or random coil when translated from a sequence
ofmRNA to a linear chain of amino acids.
This polypeptide lacks any developed three-dimensional structure.
Amino acids interact with each other to produce a well-defined three dimensional
structure, the folded protein, known as the native state. The resulting three-
dimensional structure is determined by the amino acid sequence.
For many proteins the correct three dimensional structure is essential to
function. Failure to fold into the intended shape usually produces inactive
proteins with different properties including toxic prions.
Several neurodegenerative and other diseases are believed to result from the
accumulation of misfolded (incorrectly folded) proteins.
Many allergies are caused by the folding of the proteins, for the immune system
does not produce antibodies for certain protein structures.
30. Function of proteins
• Enzymatic catalysis
• Transport and storage (the protein hemoglobin, albumins)
• Coordinated motion (actin and myosin).
• Mechanical support (collagen).
• Immune protection (antibodies)
• Generation and transmission of nerve impulses - some
amino acids act as neurotransmitters, receptors for
neurotransmitters, drugs, etc. are protein in nature. (the
acetylcholine receptor),
• Control of growth and differentiation - transcription factors
Hormones growth factors ( insulin or thyroid stimulating
hormone)
31. Enzymes
Enzymes are proteins that catalyze (i.e. speed up)
chemical reactions. Enzymes are catalysts.
Enzymes work on things called Substrates
Each enzyme is specific for its substrate
Almost all processes in a cell need enzymes in order to
occur at significant rates.
Enzymes are not used up by the reaction.
After they have done their work they release the products
and are not changed
Each enzyme can work on many molecules of the substrate
32. Lock and Key Model
The method in which enzymes work is called the lock
and key model
33. Transport and storage - small molecules are often carried by proteins
in the physiological setting (for example, the protein hemoglobin is responsible
for the transport of oxygen to tissues). Many drug molecules are partially bound
to serum albumins in the plasma.
The binding of oxygen is affected by molecules such as
carbon monoxide (CO) (for example from tobacco
smoking, cars and furnaces).
CO competes with oxygen at the heme binding site.
Hemoglobin binding affinity for CO is 200 times greater
than its affinity for oxygen, meaning that small amounts
of CO dramatically reduces hemoglobin's ability to
transport oxygen. When hemoglobin combines with
CO, it forms a very bright red compound called
carboxyhemoglobin.
When inspired air contains CO levels as low as 0.02%,
headache and nausea occur; if the CO concentration is
3-dimensional structure of hemoglobin. increased to 0.1%, unconsciousness will follow. In
The four subunits are shown in red and heavy smokers, up to 20% of the oxygen-active sites
yellow, and the heme groups in green. can be blocked by CO.
34. Coordinated motion - muscle is mostly protein, and muscle contraction is
mediated by the sliding motion of two protein filaments, actin and myosin.
Platelet activation is a controlled
sequence of actin filament:
Severing
Uncapping
Elongating
Cross linking
That creates a dramatic shape
change in the platelet
Activated platelet
Platelet before activation Activated platelet
at a later stage than C)
35. Mechanical support –
skin and bone are strengthened by the protein collagen.
Abnormal collagen synthesis
or structure causes
dysfunction of
• cardiovascular organs,
• bone,
• skin,
• joints
• eyes
Refer to Devlin
Clinical correlation 3.4 p121
36. Immune protection - antibodies are protein structures that are
responsible for reacting with specific foreign substances in the body.
37. Generation and transmission of nerve impulses
Some amino acids act as neurotransmitters, which transmit electrical
signals from one nerve cell to another. In addition, receptors for
neurotransmitters, drugs, etc. are protein in nature.
An example of this is the acetylcholine receptor, which is a protein
structure that is embedded in postsynaptic neurons.
GABA:
gamma Amino butyric acid
Synthesised from glutamate
GABA acts at inhibitory synapses in the
brain. GABA acts by binding to specific
receptors in the plasma membrane of both
pre- and postsynaptic neurons.
Neurotransmetter
38. Control of growth and differentiation -
proteins can be critical to the control of growth, cell differentiation and expression of
DNA.
For example, repressor proteins may bind to specific segments of DNA,
preventing expression and thus the formation of the product of that DNA
segment.
Also, many hormones and growth factors that regulate cell function, such as
insulin or thyroid stimulating hormone are proteins.
39. DNA is found packed in the nucleus of
eukaryotic organisms; it is found in the
cytoplasm of prokaryotic organisms
DNA is packed together and wrapped
around special proteins called HISTONES
DNA bound protein is called
CHROMATIN
When chromatin condenses (gets thicker)
it forms CHROMOSOMES
41. DNA Structure
Double Helix - twisted ladder
Made up of monomers
called nucleotides
Nucleotides are composed of:
Deoxyribose sugar
Phosphate group
Nitrogenous base
42. Nitrogenous Bases
Two types:
Purines (two rings)
Pyrimidines (one ring)
Purines
Adenine and Guanine
Pyrimidines
Thymine and Cytosine
43. Purines Pyrimidines
Adenine Guanine Cytosine Thymine
Phosphate Deoxyribose
group
44. Bonding
TEMPLATE STRAND
A C G G T A
T G C C A T
Weak HYDROGEN bonds form
between the Nitrogen Base Pairs.
45. Chargaff’s rules:
Base pairing rule is A-T and G-C
Thymine is replaced by Uracil in RNA
Bases are bonded to each other by Hydrogen bonds
Discovered because of the relative percent of each
base; (notice that A-T is similar and C-G are similar)
47. The backbone of it all…
TEMPLATE STRAND
A C G G T A
T G C C A T
The backbone is made of alternating
sugars and phosphates.
- Remember: Sugar ALWAYS
attaches to the Nitrogen base
48.
49.
50.
51.
52. Decoding the Information in DNA
How does DNA (a twisted latter of atoms) control
everything in a cell and ultimately an organism?
DNA controls the manufacture of all cellular
proteins including enzymes
A gene is a region of DNA that contains the
instructions for the manufacture of on
particular polypeptide chain (chain of amino
acids)
DNA is a set of blueprints
or code from making proteins
53. Genetic Code
Genetic code – the language of mRNA
instructions (blueprints)
Read in three letters at a time
Each letter represents one of the nitrogenous
bases: A, U, C, G
Codon found on mRNA; consists of three bases
(one right after the other)
64 codons for 20 amino acids
54. Codon (cont’d)
For example, consider the following RNA
sequence:
UCGCACGGU
The sequence would be read three base pairs at a
time:
UCG – CAC – GGU
The codons represent the amino acids:
Serine – Histidine – Glycine
AUG – start codon or Methionine
UAA, UAG, UGA – stop codons; code for nothing;
like the period at the end of a sentence
55. The gene-enzyme relationship has been
revised to the one-gene, one-polypeptide
relationship.
Example: In hemoglobin, each polypeptide
chain is specified by a separate gene.
Other genes code for RNA that is not
translated to polypeptides; some genes are
involved in controlling other genes.
56.
57. DNA & RNA
Before mitosis (during S phase of interphase) , a
complete copy of a cell’s DNA is made through a process
called replication.
When a cell divides, each daughter cell gets one
complete copy of the DNA.
Similar to photocopying a document – the end
result is two identical documents that contain the
same information.
Now that we know something about DNA’s structure,
lets look at how it replicates.
58. Steps of DNA Replication
1) DNA must unwind and break the hydrogen bonds
2) Each strand is used as a template (blueprint)
3) Two new strands of DNA are formed from the
original strand by the enzyme DNA Polymerase
60. During replication, an enzyme called helicase “unzips” the
DNA molecule along the base pairing, straight down the
middle.
Another enzyme, called DNA polymerase, moves along the
bases on each of the unzipped halves and connects
complementary nucleotides.
61. From Gene to Protein
Synthesis of DNA
from RNA is
reverse
transcription.
Viruses that do
this are
Retroviruses.
63. ow do you get from DNA to Proteins?
TRANSCRIPTION – the synthesis of RNA under the direction of
DNA
TRANSLATION – the actual synthesis of a protein,
which occurs under the direction of mRNA
64. Splicing
Each gene has it own promotor
Each gene is widely spacied
The information is fragmented
Exon = expressed gen
Intron = intervening part
Alternative splicing: A regulatory mechanism by which
variations in the incorporation of a gene’s exons, or coding
regions, into messenger RNA lead to the production of more
than one related protein, or isoform.
Alternative splicing is a source of genetic diversity in
eukaryotes.
Splicing has been used to account for the relatively small
number of genes in the human genome.
65. mRNA Splicing
The entire gene is transcripted into a message. Some of
the message is
Junk (introns) and is removed before exiting the nucleus.
A spliceosome is a complex of specialized RNA and protein
that removes introns from a pre-mRNA This process is
generally referred to as splicing.
Introns typically have a ―GU‖ nucleotide sequence at the 5' end
splice site, and an AG at the 3' end splice site.
69. Transcription- how RNA is made
Just as DNA polymerase makes new DNA, a similar
enzyme called RNA polymerase makes new RNA.
RNA polymerase temporarily separates the strands of a
small section of the DNA molecule. This exposes some of
the bases of the DNA molecule.
Along one strand, the RNA polymerase binds
complementary RNA nucleotides to the exposed DNA
bases.
An exposed thymine on the DNA strand hooks up with
an RNA nucleotide with an adenine; an exposed cytosine
on the DNA hooks up with an RNA nucleotide with a
guanine base; an exposed adenine DNA base will hook up
with URACIL!
70. As the RNA polymerase moves along, it makes a
strand of messenger RNA (mRNA).
It is called messenger RNA because it carries DNA’s
message out of the nucleus and into the cytoplasm.
mRNA is SINGLE STRANDED!
When the RNA polymerase is done reading the gene
in the DNA, it leaves.
The separated DNA strands reconnect, ready to be
read again when necessary.
mRNA moves out of the nucleus and finds a ribosome
On the ribosome, amino acids are assembled to form
proteins in the process called translation.
71. Translation: Protein Synthesis
1)mRNA is transcribed in the nucleus and leaves
the nucleus to the cytoplasm
2) mRNA attaches to the ribosome
3) tRNA carries the anticodon which pairs up
with the codon on the mRNA
4) tRNA brings the correct amino acid by reading
the genetic code
5) The amino acids are joined together to form a
polypeptide (protein)
6) When a stop codon is reached (UAA, UAG,
UGA) protein synthesis stops
72. Translation
mRNA
GUA UCU GUU ACC GUA
•mRNA carries the same message as DNA but
rewritten with different nitrogen bases.
•This message codes for a specific sequence of
amino acids
•Review..Amino acids are the building blocks
of…
•PROTEINS
73. SO:
Say the mRNA strand reads:
mRNA (codon) AUG–GAC–CAG-UGA
tRNA (anticodon) UAC-CUG-GUC-ACU
tRNA would bring the amino acids:
Methionine-Aspartic acid-Glutamine-stop
74. Translation
mRNA
GUA UCU GUU ACC GUA
•Codon: a sequence of 3 nitrogen bases on
mRNA that code for 1 amino acid
•It’s a TRIPLET code
•Example: This strand of mRNA has 5
codons, so it would code for 5 amino acids.
75. Translation
mRNA
GUA UCU GUU ACC GUA
•These codons are universal for every
bacteria, plant and animal on earth
•There are 64 codons which code for all 20
amino acids on earth.
76. The genetic code: specifies which amino
acids will be used to build a protein
Codon: a sequence of three bases. Each
codon specifies a particular amino acid.
Start codon: AUG—initiation signal for
translation
Stop codons: stops translation and
polypeptide is released
79. Translation
mRNA
GUA UCU GUU ACC GUA
Ribosome
•The mRNA molecule travels to the ribosomes
where the mRNA codes are ―read‖ by the
ribosomes
•Ribosomes hold the mRNA so another type
of RNA, transfer RNA (tRNA) can attach to the
mRNA
84. Major RNAs
mRNA
messenger RNA carries the genetic information that will be
expressed ultimately as proteins. (carries information from
DNA to ribosome)
tRNA
transfer RNA is the adapter molecule. It recognizes the codons
of the mRNA on the one hand, and it can be covalently bonded
to the appropriate amino acid, on the other. (Carries amino
acids)
rRNA
ribosomal RNA is found in the ribosomes (Makes up
ribosomes)
85. RNA-Coding Genes
A. Ribosomal RNA (rRNA) genes
B. Transfer RNA (tRNA) genes
C. Small Nuclear RNA (snRNA) genes
D. Small Nucleolar RNA (snoRNA) genes
E. Regulatory RNA genes
F. XIST RNA-Coding Genes
G. MicroRNA (miRNA) genes
H. Antisense RNA genes
I. Riboswitch genes
86. RNA
can be
Transfer
Messenger Ribosomal RNA
RNA RNA
also called which functions to also called which functions to also called
Bring
Combine
Carry rRNA tRNA amino
mRNA with proteins
instructions acids to
ribosome
from to to make up
DNA Ribosome Ribosomes
87.
88. Processing the RNA transcript into mRNA
1. Mono-cistronic
2. Maturation
a) RNA capping
b) RNA polyadenylation
c) RNA splicing
Cistron = Gene
89. Maturation of Eukatriotic mRNA
Intron: not founded in cytoplasm
Cap: 7-Methyl-Guanosine cap, protect mRNA
from degradation and serve as a ribosome
binding site
Poly-A tail: AAUAAA (200 A’s) to protect the
message from degradation
Splicing: remove of introns
Lariat structures: introns removed from hnRNA
(heterogeneus nuclear RNA) are degraded in
nucleus
93. The conformation (three-dimensional
shape) of tRNA results from base
pairing (H bonds) within the molecule.
3' end is the amino acid attachment
site—binds covalently. Always CCA.
Anticodon: site of base pairing with
mRNA. Unique for each species of
tRNA.
94. Hydrogen bonds form between the
anticodon of tRNA and the codon of
mRNA.
Small subunit rRNA validates the
match—if hydrogen bonds have not
formed between all three base pairs,
it must be an incorrect match, and
the tRNA is rejected.
95. Example:
DNA codon for arginine: 3'-GCC-5'
Complementary mRNA: 3'-CGG-5'
Anticodon on the tRNA: 3'-GCC-5' This
tRNA is charged with arginine.
TAC - ___ ____ ____ - TAC
96. Wobble: specificity for the base at the 3'
end of the codon is not always
observed.
Example: codons for alanine—GCA,
GCC, and GCU—are recognized by the
same tRNA.
97.
98. Protein formation
Amino acids link
together to form a
protein
The new protein
could become cell
part, an enzyme, a
hormone etc.
99.
100. Ribosomic RNA
50S
Prokaryotic ribosomes
have 3 rRNA
molecules:
23S, 16S and 5S. 30S
2 Subunits: 50S+30S
Eukaryotic ribosomes
have 4 rRNA
60S
molecules:
28S, 18S, 5.8S and 5S
2 Subunits: 60S+40S
40S
101. Ribosome: the workbench—holds mRNA and
tRNA in the correct positions to allow
assembly of polypeptide chain.
Ribosomes are not specific, they can make any
type of protein.
102. Prokaryotes
Small Subunit 30s Large subunit 50s
16s 5s
21 proteins 23s
34 proteins
Eukaryotes:
Small 40S Large 60S
5S
18S 28S
33 proteins 5.8S
49 proteins
**The numbers are not additive – based on centrifugation rates
103. Subunits are held together by ionic and
hydrophobic forces (not covalent
bonds).
When not active in translation, the
subunits exist separately.
105. Large subunit has three tRNA binding
sites:
• A site binds with anticodon of
charged tRNA.
• P site is where tRNA adds its amino
acid to the growing chain.
• E site is where tRNA sits before
being released.
106.
107.
108.
109. RNA polymerases
catalyze synthesis of
RNA.
RNA polymerases are
processive—a single
enzyme-template
binding results in
polymerization of
hundreds of RNA
bases.
110. Figure 12.4 RNA Polymerase
What are the bonds called that
form between ribose bases?
111. Transcription occurs in three phases:
• Initiation
• Elongation
• Termination
http://vcell.ndsu.edu/animations/transcription/movie.htm
112. Initiation requires a promoter—a special
sequence of DNA.
RNA polymerase binds to the promoter.
Promoter tells RNA polymerase where to start,
which direction to go in, and which strand of
DNA to transcribe.
Part of each promoter is the initiation site.
116. Start codon is AUG; first amino acid is
always methionine, which may be
removed after translation.
The large subunit joins the complex, the
charged tRNA is now in the P site of the
large subunit.
117. Elongation: RNA polymerase unwinds
DNA about 10 base pairs at a time;
reads template in 3' to 5' direction.
The RNA transcript is antiparallel to the
DNA template strand.
RNA polymerases do not proof read and
correct mistakes.
118. Elongation: the second charged tRNA
enters the A site.
Large subunit catalyzes two reactions:
1. Breaks bond between tRNA in P site
and its amino acid.
2. Peptide bond forms between that
amino acid and the amino acid on tRNA
in the A site.
119.
120.
121.
122.
123. Termination: specified by a specific DNA
base sequence.
Mechanisms of termination are complex and
varied.
Eukaryotes—first product is a pre-mRNA
that is longer than the final mRNA and
must undergo processing.
124. Termination: translation ends when a
stop codon enters the A site.
Stop codon binds a protein release
factor—allows hydrolysis of bond
between polypeptide chain and tRNA on
the P site.
Polypeptide chain—C terminus is the last
amino acid added.
129. Several ribosomes can work together to
translate the same mRNA, producing
multiple copies of the polypeptide.
A strand of mRNA with associated
ribosomes is called a polyribosome or
polysome.
136. Stabilizing the message
Posttranslational aspects of protein synthesis:
1. 5’ cap added to N side of new protein
How is a message
(mRNA) stabilized
to get enough
protein…at the
right time?
138. 2. Polyadenylation is the synthesis of a poly(A) tail, a stretch
of adenines at the end of the mRNA molecule.
At the end of transcription the last 3’ bit of the newly made
RNA is cleaved off by a set aof enzymes. The enzymes then
synthesize the poly(A) tail at the RNA's 3' end.
The poly(A) tail is important for the nuclear export, translation
and stability of mRNA. The tail is shortened over time and
when it is short enough, the mRNA is degraded.
In a few cell types, mRNAs with short poly(A) tails are stored
for later activation
139. Processing the protein (product)
3. TARGETING:
Polypeptide may be moved from synthesis site to an
organelle, or out of the cell.
Amino acid sequence also contains a signal sequence—an ―address label.‖
i.e. – proteins targeted to ER 5-10 hydrophobic amino acids
on the N-terminus.
142. Figure 12.16 A Signal Sequence Moves a Polypeptide into the ER (Part 2)
Folding chaperones (proteins)
in RER fold proteins appropriately.
Mis-folding diseases:
Altzheimer’s
Creutzfeld–Jakob disease (CJD) (prion disease)
P53 – cancer from misfolded ―watchdog‖
143. What Happens to Polypeptides after Translation?
4. Glycosylation: addition of sugars to form
glycoproteins Sugars may be added in the
Golgi apparatus—the resulting
glycoproteins end up in the plasma
membrane, lysosomes, or vacuoles.
Diseases: incorrect addition of sugars to
specific amino acids – shows in infancy-
almost always involves nervous system
development.
144. All proteins inserted into or associated with
the cell membrane have sugars attached to
them. They aid in recognition of other
molecules.
What would be some consequences of
incorrect glycosylation at the cell
membrane?
145. What Happens to Polypeptides after Translation?
Protein modifications:
5. Proteolysis: cutting the polypeptide
chain by proteases. Degradation of
protein message.
6. Phosphorylation: addition of phosphate
groups by kinases. Charged phosphate
groups change the conformation.
Generally makes protein into enzymes!