1. The document is Stephen Corvini's take-home test on molecular cell biology. It contains his answers to 3 questions about red blood cell membrane proteins, protein isolation techniques, and lysosomal protein transport.
2. Corvini describes how red blood cell membrane proteins like spectrin, band 3, and band 4.1 interact to regulate transport and maintain cell structure. He also explains techniques for isolating integral membrane proteins using detergents.
3. In his answers, Corvini discusses N-linked and O-linked oligosaccharides, mannose-6-phosphate receptor mediated lysosomal transport, and molecular defects in I-cell disease.
The cell membrane contains cholesterol and proteins that are vital to many cell processes. Cholesterol levels increase before cell proliferation and help maintain membrane structure. Integrin and NCAM proteins in the membrane allow communication with other cells and the environment to promote cell survival. The membrane also regulates transport of molecules in and out of the cell through passive diffusion, pumps, and carrier proteins. Phagocytosis relies on phospholipases and other molecules to engulf cellular debris. Overall, the complex but foundational cell membrane enables critical functions through its composition and structure.
1. Eukaryotic cells transport materials between membrane-bound organelles using vesicles that bud from donor membranes and fuse with acceptor membranes.
2. Vesicles are covered by a protein coat that helps select cargo and facilitates membrane bending and vesicle formation. The coat also provides targeting to ensure vesicles fuse with the correct acceptor membrane.
3. Vesicle transport systems move materials through the cell in a regulated manner to allow for biosynthesis and organelle function. Defects in these transport pathways can lead to disease.
A ribosome is a complex cellular mechanism used to translate genetic code into chains of amino acids.
Long chains of amino acids fold and function as proteins in cells.
The document is Stephen Corvini's answers to questions on a molecular cell biology test. It contains his responses to 4 questions. For question 1, he summarizes the role of integral membrane proteins in red blood cells. For question 2, he discusses N-linked and O-linked oligosaccharides and their roles in protein glycosylation and transport to lysosomes. For question 3, he explains receptor tyrosine kinases and their signaling mechanisms. For question 4, he defines the functions of topoisomerase I and II.
Cell adhesion molecules help cells stick to each other and their surroundings through proteins. There are several types of cell adhesion molecules including immunoglobulin super family CAMs, integrins, selectins, and cadherins. Cadherins like E-cadherin form adherens junctions between cells and link to actin through catenins. Changes in cell adhesion can lead to diseases such as cancer where reduced adhesion allows cancer cells to invade other tissues. Cell adhesion molecules are important for tissue development and function.
Unit 2-plasma membrane and membrane transportKomal Kp
The document discusses the plasma membrane and membrane transport. It defines the plasma membrane as the outer membrane of the cell composed of a phospholipid bilayer with embedded proteins. The plasma membrane regulates what enters and exits the cell and maintains the integrity of the cell's interior. Membrane transport involves the passage of solutes through the membrane via passive diffusion or with the aid of transport proteins and can occur down a concentration gradient or against it with active transport.
This document provides an overview of the cell cycle and its regulation. It describes the main phases of the cell cycle (G1, S, G2, M) and key regulatory molecules like cyclins and cyclin-dependent kinases (CDKs). Cyclin-CDK complexes drive progression through the cell cycle by phosphorylating target proteins. There are three major checkpoints (G1, G2/M, metaphase) that ensure cellular conditions are suitable before progressing to the next phase. The document discusses these checkpoints and their control mechanisms in detail.
The cell membrane contains cholesterol and proteins that are vital to many cell processes. Cholesterol levels increase before cell proliferation and help maintain membrane structure. Integrin and NCAM proteins in the membrane allow communication with other cells and the environment to promote cell survival. The membrane also regulates transport of molecules in and out of the cell through passive diffusion, pumps, and carrier proteins. Phagocytosis relies on phospholipases and other molecules to engulf cellular debris. Overall, the complex but foundational cell membrane enables critical functions through its composition and structure.
1. Eukaryotic cells transport materials between membrane-bound organelles using vesicles that bud from donor membranes and fuse with acceptor membranes.
2. Vesicles are covered by a protein coat that helps select cargo and facilitates membrane bending and vesicle formation. The coat also provides targeting to ensure vesicles fuse with the correct acceptor membrane.
3. Vesicle transport systems move materials through the cell in a regulated manner to allow for biosynthesis and organelle function. Defects in these transport pathways can lead to disease.
A ribosome is a complex cellular mechanism used to translate genetic code into chains of amino acids.
Long chains of amino acids fold and function as proteins in cells.
The document is Stephen Corvini's answers to questions on a molecular cell biology test. It contains his responses to 4 questions. For question 1, he summarizes the role of integral membrane proteins in red blood cells. For question 2, he discusses N-linked and O-linked oligosaccharides and their roles in protein glycosylation and transport to lysosomes. For question 3, he explains receptor tyrosine kinases and their signaling mechanisms. For question 4, he defines the functions of topoisomerase I and II.
Cell adhesion molecules help cells stick to each other and their surroundings through proteins. There are several types of cell adhesion molecules including immunoglobulin super family CAMs, integrins, selectins, and cadherins. Cadherins like E-cadherin form adherens junctions between cells and link to actin through catenins. Changes in cell adhesion can lead to diseases such as cancer where reduced adhesion allows cancer cells to invade other tissues. Cell adhesion molecules are important for tissue development and function.
Unit 2-plasma membrane and membrane transportKomal Kp
The document discusses the plasma membrane and membrane transport. It defines the plasma membrane as the outer membrane of the cell composed of a phospholipid bilayer with embedded proteins. The plasma membrane regulates what enters and exits the cell and maintains the integrity of the cell's interior. Membrane transport involves the passage of solutes through the membrane via passive diffusion or with the aid of transport proteins and can occur down a concentration gradient or against it with active transport.
This document provides an overview of the cell cycle and its regulation. It describes the main phases of the cell cycle (G1, S, G2, M) and key regulatory molecules like cyclins and cyclin-dependent kinases (CDKs). Cyclin-CDK complexes drive progression through the cell cycle by phosphorylating target proteins. There are three major checkpoints (G1, G2/M, metaphase) that ensure cellular conditions are suitable before progressing to the next phase. The document discusses these checkpoints and their control mechanisms in detail.
This document provides information on cellular interactions through the extracellular matrix (ECM). It discusses the composition and functions of the ECM, including proteoglycans, glycosaminoglycans, fibers like collagen, and other components such as hyaluronic acid. The roles of the ECM in cell communication, growth factor storage, and mechanosensing are described. Details are provided on the synthesis of ECM components both intracellularly and after secretion from the cell.
Structure and functions of endoplasmic reticulumICHHA PURAK
The presentation consists of 57 slides,describes following heads
• DISCOVERY
• INTRODUCTION
• BIOGENESIS OF ER
• ISOLATION OF MICROSOMES FROM E R
• STRUCTURE
• COMPONENTS OF ER
CISTERNAE
VESICLES
TUBULES
• MAIN FUNCTION OF ER
• TYPES OF ENDOPLASMIC RETICULUM
• SMOOTH ENDOPLASMIC RETICULUM (SER)
• FUNCTIONS OF SER
• ROUGH ENDOPLASMIC RETICULUM (RER)
• FUNCTIONS OF RER
• SUMMARY
• REFERENCES
• QUESTIONS
Mitochondria are membrane-bound organelles found in eukaryotic cells that produce energy through respiration. They were first observed by Richard Altmann and named by Benda. Mitochondria have an outer and inner membrane, with cristae extending inward from the inner membrane. They contain their own DNA and ribosomes. Mitochondria play key roles in cellular metabolism and energy production.
This document discusses cell adhesion molecules (CAMs), which are glycoproteins located on cell surfaces that help cells stick to each other and their surroundings. CAMs are classified into five major families: cadherins, Ig superfamily CAMs, selectins, integrins, and mucins. Cadherins are calcium-dependent and form connections between cells called desmosomes. Selectins help with inflammation and lymphocyte homing. Integrins facilitate cell-cell and cell-extracellular matrix adhesion and are composed of alpha and beta subunits. Malfunctions in CAMs can lead to conditions like breast cancer and leukocyte adhesion deficiency syndrome.
The document discusses the endoplasmic reticulum (ER), which is an extensive membrane network inside cells. It has two regions: the smooth ER and rough ER. The rough ER is studded with ribosomes and finishes making proteins. It is important for producing proteins that are essential for other organelles to function. The smooth ER produces lipids, engages in metabolism, and makes steroid hormones. It is also involved in detoxification. Dysfunctions of the ER and unfolded protein response are associated with neurodegenerative diseases like Parkinson's and kidney diseases. Treating ER stress may aid in diagnosis and treatment of such diseases.
The extracellular matrix (ECM) is a collection of molecules secreted by cells that provides structural and biochemical support to surrounding cells. It is composed of water, proteins, and polysaccharides. The ECM contains collagens, fibronectin, laminins, and proteoglycans. Collagen is the most abundant protein in the ECM and forms fibrils that provide structure. The ECM regulates cell behavior, provides tissue structure and strength, and mediates cell signaling and homeostasis. Genetic defects in ECM proteins can cause diseases like osteogenesis imperfecta or fibrosis.
The document summarizes the endoplasmic reticulum (ER), an organelle found within eukaryotic cells. It was discovered in 1902 by Emilio Verrati but his work was initially disregarded. In the 1950s, Keith Porter and George Palade used electron microscopy to rediscover and prove the existence of the ER. The ER is a network of tubules and sacs that functions to produce and transport proteins and lipids. It exists in two forms: rough ER with ribosomes on its surface for protein synthesis, and smooth ER involved in lipid and steroid production. Current research explores how ER stress contributes to diseases like Alzheimer's, Parkinson's, and diabetes.
The document summarizes recent findings regarding two Arabidopsis mutants involved in plant cell expansion.
The first mutant is rsw1, which encodes a subunit of cellulose synthase. At restrictive temperatures, rsw1 cells produce non-crystalline glucan instead of cellulose microfibrils. This supports the role of RSW1 in cellulose synthesis.
The second mutant is korrigan, which encodes an unusual endo-1,4-β-glucanase enzyme. kor cells have thick, undulating cell walls that lack the layered microfibril structure of wild-type walls. This suggests KORRIGAN is involved in remodeling of the cell wall during
The endoplasmic reticulum (ER) is a network of interconnected membranes found throughout the cytoplasm of eukaryotic cells. It consists of flat sacs and tubules with a single continuous lumen. The ER is involved in protein transport and synthesis, lipid and steroid synthesis, calcium storage, and processing of toxins. It has two types - smooth ER which lacks ribosomes and is involved in lipid synthesis, and rough ER which is studded with ribosomes and is the main site of protein synthesis.
The document is a presentation on the nucleus and endoplasmic reticulum. It begins with background on the discovery of the nucleus by Leeuwenhoek and others. It then defines the nucleus as the control center of the cell that contains most of the cell's genetic material. It describes the main characteristics, size, shape, and ultrastructure of the nucleus, including the nuclear envelope, pores, lamina, chromosomes, nucleolus, and other components. It also summarizes the functions of the nucleus and endoplasmic reticulum, who discovered the ER, its definition, structure including cisternae, tubules and vesicles, types (rough and smooth ER), and functions in protein transport and synthesis.
This document summarizes different types of cell adhesion molecules (CAMs). It discusses cadherins, which are the primary CAMs in adherens junctions and desmosomes. Integrins are heterodimeric receptors that connect the intracellular and extracellular environments and are involved in cell adhesion to the extracellular matrix. The immunoglobulin superfamily of CAMs are calcium-independent transmembrane proteins with immunoglobulin-like domains. Selectins mediate the initial tethering of leukocytes to endothelial cells during inflammation. Cell adhesion molecules play important roles in processes like embryogenesis, immunity, tissue development, and cancer metastasis.
The nucleus is the control center of eukaryotic cells that contains DNA and directs protein synthesis and cell regulation. It is enclosed by a double membrane and contains nucleoplasm, nucleoli, and chromatin. Chromatin contains DNA and histone proteins that package DNA into chromosomes. The nuclear envelope separates the nucleus from the cytoplasm while nuclear pores allow transport of molecules. The nucleolus produces ribosomes and rRNA. The nucleus controls DNA replication, protein production, and cell processes through gene expression and protein synthesis.
The extracellular matrix (ECM) provides physical scaffolding and biochemical signals outside cells that are essential for tissue development and homeostasis. The ECM is composed of glycoproteins like collagen and proteoglycans that form a network, as well as glycoproteins like fibronectin that attach cells to the network. Collagen provides tensile strength and there are various types of collagen with different structures and functions. The ECM allows communication between cells through connections like tight junctions, desmosomes, and gap junctions. It also binds growth factors and interacts with cell receptors to regulate gene expression. Disruptions to the ECM can cause diseases like scurvy or emphysema.
This document summarizes key concepts in cell biology related to protein sorting and transport within the endoplasmic reticulum (ER) and Golgi apparatus. It discusses how molecular chaperones in the ER assist with protein folding and transport proteins to the Golgi if folding is successful. The Golgi apparatus further processes proteins and lipids from the ER, modifying them through glycosylation, phosphorylation, and synthesis of sphingomyelin and glycolipids. Transport from the Golgi can then deliver proteins and lipids to their final destinations, such as the plasma membrane or lysosomes.
The endoplasmic reticulum (ER) is an organelle found in eukaryotic cells that consists of a network of membrane sacs and tubules. The ER has two main types: rough ER and smooth ER. Rough ER is studded with ribosomes and is the site of protein synthesis, while smooth ER lacks ribosomes and is involved in lipid and steroid synthesis. In skeletal muscle cells, smooth ER forms the sarcoplasmic reticulum, which stores and releases calcium ions to regulate muscle contraction. Without the ER, cells would not be able to synthesize proteins or lipids, carry out important metabolic processes, and in muscle cells, regulate contraction, likely resulting in cell death.
Cell junctions allow cells to adhere to each other and communicate. There are three main types of junctions: occluding junctions which prevent diffusion between cells like tight junctions, anchoring junctions which mechanically attach cells like desmosomes, and communicating junctions which allow cell-cell communication like gap junctions. Transport across the plasma membrane can occur passively through diffusion or actively through protein pumps and channels. Endocytosis and exocytosis allow cells to take in and release material through membrane vesicles.
Günter Blobel and Bernhard Dobberstein provided experimental evidence supporting the signal hypothesis proposed earlier by Blobel and Sabatini. Through in vitro translation experiments using membrane-bound ribosomes from murine myeloma cells, they showed that immunoglobulin light chains containing an amino-terminal signal sequence were incorporated into the microsomal membranes and had the signal cleaved, while light chains lacking a signal sequence were not incorporated. This provided strong evidence that a signal sequence on the nascent polypeptide targets it for attachment to the membrane during translation.
The document discusses the key components and structure of the nucleus. It notes that the nucleus was discovered in 1831 and is located at the center of most cells, where it controls cell activities and houses genetic material. The nucleus contains a double-layered nuclear envelope that encloses chromosomes, nucleolus, and nucleoplasm. Chromosomes contain DNA that provides genetic instructions, while the nucleolus produces ribosomes and the nucleoplasm is a liquid found within the nuclear envelope.
Molecular chaperones play an important role in protein folding and preventing misfolding. The document discusses protein folding mechanisms and the roles of chaperones like GroEL/GroES complex. It summarizes protein folding, mechanisms of proteostasis including chaperones and quality control systems that help maintain protein homeostasis. The GroEL/GroES chaperone system is described in detail with its mechanism of encapsulating proteins to allow folding in an ATP-dependent manner.
Deciphering the regulatory code in the genomeDenis C. Bauer
There are messages hidden within our genome, regulating when and how long a gene is switched on. The presentation describes a method, STREAM, targeted at deciphering this regulatory code.
This document provides information on cellular interactions through the extracellular matrix (ECM). It discusses the composition and functions of the ECM, including proteoglycans, glycosaminoglycans, fibers like collagen, and other components such as hyaluronic acid. The roles of the ECM in cell communication, growth factor storage, and mechanosensing are described. Details are provided on the synthesis of ECM components both intracellularly and after secretion from the cell.
Structure and functions of endoplasmic reticulumICHHA PURAK
The presentation consists of 57 slides,describes following heads
• DISCOVERY
• INTRODUCTION
• BIOGENESIS OF ER
• ISOLATION OF MICROSOMES FROM E R
• STRUCTURE
• COMPONENTS OF ER
CISTERNAE
VESICLES
TUBULES
• MAIN FUNCTION OF ER
• TYPES OF ENDOPLASMIC RETICULUM
• SMOOTH ENDOPLASMIC RETICULUM (SER)
• FUNCTIONS OF SER
• ROUGH ENDOPLASMIC RETICULUM (RER)
• FUNCTIONS OF RER
• SUMMARY
• REFERENCES
• QUESTIONS
Mitochondria are membrane-bound organelles found in eukaryotic cells that produce energy through respiration. They were first observed by Richard Altmann and named by Benda. Mitochondria have an outer and inner membrane, with cristae extending inward from the inner membrane. They contain their own DNA and ribosomes. Mitochondria play key roles in cellular metabolism and energy production.
This document discusses cell adhesion molecules (CAMs), which are glycoproteins located on cell surfaces that help cells stick to each other and their surroundings. CAMs are classified into five major families: cadherins, Ig superfamily CAMs, selectins, integrins, and mucins. Cadherins are calcium-dependent and form connections between cells called desmosomes. Selectins help with inflammation and lymphocyte homing. Integrins facilitate cell-cell and cell-extracellular matrix adhesion and are composed of alpha and beta subunits. Malfunctions in CAMs can lead to conditions like breast cancer and leukocyte adhesion deficiency syndrome.
The document discusses the endoplasmic reticulum (ER), which is an extensive membrane network inside cells. It has two regions: the smooth ER and rough ER. The rough ER is studded with ribosomes and finishes making proteins. It is important for producing proteins that are essential for other organelles to function. The smooth ER produces lipids, engages in metabolism, and makes steroid hormones. It is also involved in detoxification. Dysfunctions of the ER and unfolded protein response are associated with neurodegenerative diseases like Parkinson's and kidney diseases. Treating ER stress may aid in diagnosis and treatment of such diseases.
The extracellular matrix (ECM) is a collection of molecules secreted by cells that provides structural and biochemical support to surrounding cells. It is composed of water, proteins, and polysaccharides. The ECM contains collagens, fibronectin, laminins, and proteoglycans. Collagen is the most abundant protein in the ECM and forms fibrils that provide structure. The ECM regulates cell behavior, provides tissue structure and strength, and mediates cell signaling and homeostasis. Genetic defects in ECM proteins can cause diseases like osteogenesis imperfecta or fibrosis.
The document summarizes the endoplasmic reticulum (ER), an organelle found within eukaryotic cells. It was discovered in 1902 by Emilio Verrati but his work was initially disregarded. In the 1950s, Keith Porter and George Palade used electron microscopy to rediscover and prove the existence of the ER. The ER is a network of tubules and sacs that functions to produce and transport proteins and lipids. It exists in two forms: rough ER with ribosomes on its surface for protein synthesis, and smooth ER involved in lipid and steroid production. Current research explores how ER stress contributes to diseases like Alzheimer's, Parkinson's, and diabetes.
The document summarizes recent findings regarding two Arabidopsis mutants involved in plant cell expansion.
The first mutant is rsw1, which encodes a subunit of cellulose synthase. At restrictive temperatures, rsw1 cells produce non-crystalline glucan instead of cellulose microfibrils. This supports the role of RSW1 in cellulose synthesis.
The second mutant is korrigan, which encodes an unusual endo-1,4-β-glucanase enzyme. kor cells have thick, undulating cell walls that lack the layered microfibril structure of wild-type walls. This suggests KORRIGAN is involved in remodeling of the cell wall during
The endoplasmic reticulum (ER) is a network of interconnected membranes found throughout the cytoplasm of eukaryotic cells. It consists of flat sacs and tubules with a single continuous lumen. The ER is involved in protein transport and synthesis, lipid and steroid synthesis, calcium storage, and processing of toxins. It has two types - smooth ER which lacks ribosomes and is involved in lipid synthesis, and rough ER which is studded with ribosomes and is the main site of protein synthesis.
The document is a presentation on the nucleus and endoplasmic reticulum. It begins with background on the discovery of the nucleus by Leeuwenhoek and others. It then defines the nucleus as the control center of the cell that contains most of the cell's genetic material. It describes the main characteristics, size, shape, and ultrastructure of the nucleus, including the nuclear envelope, pores, lamina, chromosomes, nucleolus, and other components. It also summarizes the functions of the nucleus and endoplasmic reticulum, who discovered the ER, its definition, structure including cisternae, tubules and vesicles, types (rough and smooth ER), and functions in protein transport and synthesis.
This document summarizes different types of cell adhesion molecules (CAMs). It discusses cadherins, which are the primary CAMs in adherens junctions and desmosomes. Integrins are heterodimeric receptors that connect the intracellular and extracellular environments and are involved in cell adhesion to the extracellular matrix. The immunoglobulin superfamily of CAMs are calcium-independent transmembrane proteins with immunoglobulin-like domains. Selectins mediate the initial tethering of leukocytes to endothelial cells during inflammation. Cell adhesion molecules play important roles in processes like embryogenesis, immunity, tissue development, and cancer metastasis.
The nucleus is the control center of eukaryotic cells that contains DNA and directs protein synthesis and cell regulation. It is enclosed by a double membrane and contains nucleoplasm, nucleoli, and chromatin. Chromatin contains DNA and histone proteins that package DNA into chromosomes. The nuclear envelope separates the nucleus from the cytoplasm while nuclear pores allow transport of molecules. The nucleolus produces ribosomes and rRNA. The nucleus controls DNA replication, protein production, and cell processes through gene expression and protein synthesis.
The extracellular matrix (ECM) provides physical scaffolding and biochemical signals outside cells that are essential for tissue development and homeostasis. The ECM is composed of glycoproteins like collagen and proteoglycans that form a network, as well as glycoproteins like fibronectin that attach cells to the network. Collagen provides tensile strength and there are various types of collagen with different structures and functions. The ECM allows communication between cells through connections like tight junctions, desmosomes, and gap junctions. It also binds growth factors and interacts with cell receptors to regulate gene expression. Disruptions to the ECM can cause diseases like scurvy or emphysema.
This document summarizes key concepts in cell biology related to protein sorting and transport within the endoplasmic reticulum (ER) and Golgi apparatus. It discusses how molecular chaperones in the ER assist with protein folding and transport proteins to the Golgi if folding is successful. The Golgi apparatus further processes proteins and lipids from the ER, modifying them through glycosylation, phosphorylation, and synthesis of sphingomyelin and glycolipids. Transport from the Golgi can then deliver proteins and lipids to their final destinations, such as the plasma membrane or lysosomes.
The endoplasmic reticulum (ER) is an organelle found in eukaryotic cells that consists of a network of membrane sacs and tubules. The ER has two main types: rough ER and smooth ER. Rough ER is studded with ribosomes and is the site of protein synthesis, while smooth ER lacks ribosomes and is involved in lipid and steroid synthesis. In skeletal muscle cells, smooth ER forms the sarcoplasmic reticulum, which stores and releases calcium ions to regulate muscle contraction. Without the ER, cells would not be able to synthesize proteins or lipids, carry out important metabolic processes, and in muscle cells, regulate contraction, likely resulting in cell death.
Cell junctions allow cells to adhere to each other and communicate. There are three main types of junctions: occluding junctions which prevent diffusion between cells like tight junctions, anchoring junctions which mechanically attach cells like desmosomes, and communicating junctions which allow cell-cell communication like gap junctions. Transport across the plasma membrane can occur passively through diffusion or actively through protein pumps and channels. Endocytosis and exocytosis allow cells to take in and release material through membrane vesicles.
Günter Blobel and Bernhard Dobberstein provided experimental evidence supporting the signal hypothesis proposed earlier by Blobel and Sabatini. Through in vitro translation experiments using membrane-bound ribosomes from murine myeloma cells, they showed that immunoglobulin light chains containing an amino-terminal signal sequence were incorporated into the microsomal membranes and had the signal cleaved, while light chains lacking a signal sequence were not incorporated. This provided strong evidence that a signal sequence on the nascent polypeptide targets it for attachment to the membrane during translation.
The document discusses the key components and structure of the nucleus. It notes that the nucleus was discovered in 1831 and is located at the center of most cells, where it controls cell activities and houses genetic material. The nucleus contains a double-layered nuclear envelope that encloses chromosomes, nucleolus, and nucleoplasm. Chromosomes contain DNA that provides genetic instructions, while the nucleolus produces ribosomes and the nucleoplasm is a liquid found within the nuclear envelope.
Molecular chaperones play an important role in protein folding and preventing misfolding. The document discusses protein folding mechanisms and the roles of chaperones like GroEL/GroES complex. It summarizes protein folding, mechanisms of proteostasis including chaperones and quality control systems that help maintain protein homeostasis. The GroEL/GroES chaperone system is described in detail with its mechanism of encapsulating proteins to allow folding in an ATP-dependent manner.
Deciphering the regulatory code in the genomeDenis C. Bauer
There are messages hidden within our genome, regulating when and how long a gene is switched on. The presentation describes a method, STREAM, targeted at deciphering this regulatory code.
Presentation of our data and results from the first antibody staining of the new allele, evePJ4 (created by Dr. Amy Bejsovec\'s lab) and the wgNE2 allele.
The document discusses the structure of hemoglobin and how its structure allows it to effectively transport oxygen throughout the body. It details that hemoglobin is a tetrameric protein containing heme groups that bind oxygen. The intersections of the protein's alpha helices form binding sites for oxygen molecules. There are three main types of hemoglobin that have similar structures but can be modified through bonding with other molecules or under certain conditions, altering their oxygen affinity. The structure of hemoglobin plays a crucial role in its function as an oxygen carrier in the blood.
The engrailed gene is a segment polarity gene in Drosophila melanogaster that plays several important roles during development. It defines the posterior region of each embryonic parasegment, establishing anterior-posterior polarity. The engrailed gene also helps pattern the brain by defining borders between regions and guiding neuronal axon growth. Comparisons of engrailed DNA and protein sequences across species show it is conserved and related genes can be found in vertebrates as well.
Developmental cascade of morphogens Define Drosophila Body PlanDouglas Easton
The expression of genes in specific regions of the early Drosophila embryo determine the anterior-posterior and dorso-ventral axes of the organism. Expression of these genes are both spatially and temporally coordinated.
The document provides an overview of computational chemistry methods for structure-activity relationship analysis, pharmacophore modeling, and protein-ligand docking. It discusses topics like SAR, QSAR, molecular alignment, conformational analysis, homology modeling of protein targets, and docking programs. Examples are given of applying these methods to study benzodiazepine ligands and GABA receptor subtypes.
Gene expression in eukaryotes is regulated through multiple mechanisms at the transcriptional and post-transcriptional levels. These mechanisms allow for adaptation, tissue specificity, and development. Regulation occurs through chromatin remodeling, enhancers/repressors, locus control regions, gene amplification, rearrangement, and alternative RNA processing. Key differences between prokaryotic and eukaryotic gene expression include larger eukaryotic genomes, different cell types, lack of operons, chromatin structure, and uncoupled transcription/translation.
Artificial intelligence (AI) is everywhere, promising self-driving cars, medical breakthroughs, and new ways of working. But how do you separate hype from reality? How can your company apply AI to solve real business problems?
Here’s what AI learnings your business should keep in mind for 2017.
1. Endocytosis and exocytosis are processes by which cells move materials into and out of the cell through the cell membrane. Endocytosis involves a part of the cell membrane enclosing extracellular fluids and molecules and breaking off into a vesicle inside the cell. Exocytosis involves secretory vesicles fusing with the plasma membrane and releasing their contents outside the cell.
2. There are several types of endocytosis, including phagocytosis which engulfs large particles, pinocytosis which absorbs fluids, and receptor-mediated endocytosis which selectively uptakes specific molecules bound to cell surface receptors.
3. Exocytosis releases contents from secretory vesicles to the extracellular space by vesicle fusion with the plasma membrane. It is important for
Recepter mediated endocytosis by kk ashuKAUSHAL SAHU
INTRODUCTION
DEFINITION OF RECEPTOR MEDIATED ENDOCYTOSIS
WHAT TYPE OF LIGANDS ENTER BY RME?
FORMATION OF CLATHRIN-COATED VESICLES
TRISKELIONS
ROLE OF DYNAMIN IN THE FORMATION OF CLATHRIN-COATED VESICLES
ROLE OF PHOSPHOLIPIDS IN THE FORMATION OF COATED VESICLES
ENDOCYTIC PATHWAY
LDLs AND CHOLESTROL METABOLISM
CONCLUSION
REFERENCES
Organelles interact to carry out important cellular processes like material uptake/release, protein synthesis, and digestion.
(1) Endocytosis and exocytosis allow cells to take in and release material through vesicle trafficking between the plasma membrane and endosomes/lysosomes. (2) The ER and Golgi apparatus work together to synthesize, modify, and transport proteins, with the ER producing proteins and the Golgi processing and packaging them. (3) Lysosomes digest material through phagocytosis, autophagy, and other pathways, while the proteasome degrades unwanted cytosolic proteins. Defects in these organelle interactions can cause diseases.
Physiological And Pathological Systems Within The...Deb Birch
Redox signalling is an important electron transfer process that regulates many physiological and pathological systems in the circulatory system. It is usually induced by reactive oxygen species and can alter cell processes. Redox signalling involves thiol-based redox couples that regulate imbalances in redox potentials and are linked to changes in redox potentials. Cysteine is an amino acid that can undergo oxidative modifications to perform different functions as part of redox signalling.
The document summarizes key components and functions of eukaryotic cells. It describes the cell membrane as composed of proteins, lipids, and carbohydrates that act as a selective barrier. It also discusses several intracellular organelles - the nucleus, mitochondria, endoplasmic reticulum, Golgi complex, ribosomes, lysosomes - and their roles in processes like protein synthesis, energy production, metabolism, and waste digestion. The plasma membrane, organelles, and their specialized functions allow cells to carry out life's processes.
The document discusses the structure and functions of cell membranes. It notes that membranes are composed of phospholipids, glycolipids, cholesterol and proteins. Membranes form a selectively permeable barrier and establish concentration gradients. They localize enzymes and processes like transport, signaling, endocytosis and exocytosis. The fluid mosaic model describes membranes as a fluid structure with proteins embedded and diffusing. Membrane composition and fluidity impact functions like signaling, vesicle movement and cell division.
The document summarizes key aspects of cell membrane structure and function. It describes the fluid mosaic model of the membrane structure consisting of a phospholipid bilayer with embedded proteins. It discusses the components of the membrane including phospholipids, cholesterol, and carbohydrates. It explains the major functions of membrane proteins including transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular joining, and attachment to the cytoskeleton. It also summarizes the different types of transport processes like diffusion, facilitated diffusion, active transport and examples of transport proteins and mechanisms.
The plasma membrane surrounds cells and organelles, protecting the interior while regulating what passes in and out. It is a selectively permeable lipid bilayer containing proteins. The fluid mosaic model describes its structure as lipids and proteins moving freely within. Membranes are composed mainly of phospholipids, cholesterol, and glycolipids, with integral and peripheral proteins embedded. Transport across membranes includes passive diffusion, facilitated diffusion using carrier proteins, and active transport using ATP. Receptors on the surface receive signals from outside the cell.
This document discusses various modes of nanoparticle (NP) interaction with cells, including adhesion and cellular uptake via receptor-mediated endocytosis, caveolin-mediated endocytosis, clathrin-mediated endocytosis, and clathrin- and caveolin-independent pathways. It also describes methods to determine the intracellular fate of NPs, such as using markers to track localization in lysosomes or the cytoplasm over time, as well as techniques to distinguish intact from degraded NPs. The ideal properties for NPs to cross the blood-brain barrier and enter the brain are also discussed.
Structure and function of plasma membrane 2ICHHA PURAK
The presentation consists of 72 slides,describes following heads
DEFINITION : STRUCTURE OF PLASMA MEMBRANE
COMPONENTS OF PLASMA MEMBRANE ( (BIOCHEMICAL PROPERTIES)
LIPID BILAYER
PROTEINS
CARBOHYDRATES
CHOLESTEROL
MODELS EXPLAINING STRUCTURE OF BIO MEMBRANE
FLUID MOSAIC MODEL
MOBILITY OF MEMBRANE
GLYCOCALYX : GLYCOPROTEINS AND GLYCOLIPIDS
TRANSPORT OF IONS AND MOLECULES ACROSS PLASMA MEMBRANE
FUNCTIONS OF PLASMA MEMBRANE
DIVERSITY OF CELL MEMBRANES
SITE OF ATPASE ION CARRIER CHANNELS AND PUMPS-RECEPTORS
Hormones act as chemical messengers that bind to receptors and elicit responses in target cells. There are three main types of chemical messengers based on their method of travel: endocrine (travel via bloodstream), paracrine (travel between nearby cells), and autocrine (act on the producing cell). Hormone receptors contain sites for ligand binding and signal transmission. When a hormone binds its receptor, it triggers intracellular responses such as changes in gene expression that produce physiological effects. Termination of signaling is important to regulate responses and prevent improper cell growth.
The endoplasmic reticulum (ER) is an organelle found in eukaryotic cells that forms an interconnected network of tubules, vesicles, and cisternae. It has two main types - rough ER with ribosomes and smooth ER without. The rough ER is involved in protein synthesis and modification, while the smooth ER performs functions like lipid synthesis and calcium regulation. Newly synthesized proteins are transported from the ER to the Golgi apparatus in vesicles for further processing and modification before being packaged into secretory vesicles and transported throughout the cell. The ER also plays a key role in protein folding and quality control.
The human body contains over 200 cell types that all originate from a single fertilized egg cell. Cells differentiate and specialize to perform specific functions. The basic components of cells are the nucleus, which houses the DNA, and the cytoplasm, which contains organelles. The plasma membrane encloses the cell and regulates what enters and exits. Cells communicate through signaling molecules that bind receptors and trigger intracellular signal transduction pathways. Endocytosis and exocytosis allow materials to be transported into and out of cells while maintaining membrane integrity. The nucleus contains DNA and directs cellular activities through gene expression.
The document describes the organization of cells and various cellular organelles. It discusses the structure and functions of mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes, peroxisomes, and nucleus. Mitochondria generate energy through oxidative phosphorylation. The endoplasmic reticulum and Golgi apparatus are involved in protein modification and transport. Lysosomes contain enzymes for intracellular digestion. Peroxisomes contain enzymes for lipid metabolism. The nucleus contains DNA and directs gene expression and protein synthesis.
The document discusses the structure and functions of the cell membrane. It describes the membrane as having a lipid bilayer structure composed of phospholipids, cholesterol, and glycolipids. Integral and peripheral membrane proteins are embedded within or attached to this bilayer. The fluid mosaic model represents membranes as a fluid structure containing phospholipids that move freely and proteins that diffuse laterally. Key functions of the membrane include selectively regulating what passes in and out of cells and serving as anchors and mediators of cell communication.
1. Nanoparticles can interact with cells through adhesion to the cell surface or cellular uptake via endocytosis or phagocytosis.
2. Cellular uptake of nanoparticles occurs mainly through clathrin-mediated endocytosis, caveolae-mediated endocytosis, macropinocytosis, or phagocytosis depending on the nanoparticle size.
3. The most common intracellular fate of nanoparticles is entrance and degradation within lysosomes, but some nanoparticles may avoid lysosomal degradation.
The red blood cell membrane consists of three layers - an outer glycocalyx, lipid bilayer in the middle, and inner phospholipid and cholesterol layer. The lipid bilayer contains phospholipids like phosphatidylcholine and sphingomyelin in the outer monolayer, and phosphatidylethanolamine, phosphatidylserine, and phosphoinositol in the inner monolayer. Transport proteins maintain this asymmetric distribution, which is important for cell integrity and survival. The membrane also contains proteins that contribute to cell structure, transport, adhesion, and signaling.
The cell membrane, also known as the plasma membrane, defines the boundary of the cell and regulates what passes in and out. It is composed primarily of lipids and proteins arranged in a fluid mosaic structure. This structure allows the membrane to perform critical functions for the cell like controlling transport, sending and receiving signals, and interacting with other cells. The fluid mosaic model best explains the dynamic and semipermeable nature of the cell membrane.
Main Java[All of the Base Concepts}.docxadhitya5119
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This slide is special for master students (MIBS & MIFB) in UUM. Also useful for readers who are interested in the topic of contemporary Islamic banking.
How to Build a Module in Odoo 17 Using the Scaffold MethodCeline George
Odoo provides an option for creating a module by using a single line command. By using this command the user can make a whole structure of a module. It is very easy for a beginner to make a module. There is no need to make each file manually. This slide will show how to create a module using the scaffold method.
How to Manage Your Lost Opportunities in Odoo 17 CRMCeline George
Odoo 17 CRM allows us to track why we lose sales opportunities with "Lost Reasons." This helps analyze our sales process and identify areas for improvement. Here's how to configure lost reasons in Odoo 17 CRM
it describes the bony anatomy including the femoral head , acetabulum, labrum . also discusses the capsule , ligaments . muscle that act on the hip joint and the range of motion are outlined. factors affecting hip joint stability and weight transmission through the joint are summarized.
Walmart Business+ and Spark Good for Nonprofits.pdfTechSoup
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Strategies for Effective Upskilling is a presentation by Chinwendu Peace in a Your Skill Boost Masterclass organisation by the Excellence Foundation for South Sudan on 08th and 09th June 2024 from 1 PM to 3 PM on each day.
Exploiting Artificial Intelligence for Empowering Researchers and Faculty, In...Dr. Vinod Kumar Kanvaria
Exploiting Artificial Intelligence for Empowering Researchers and Faculty,
International FDP on Fundamentals of Research in Social Sciences
at Integral University, Lucknow, 06.06.2024
By Dr. Vinod Kumar Kanvaria
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How to Fix the Import Error in the Odoo 17Celine George
An import error occurs when a program fails to import a module or library, disrupting its execution. In languages like Python, this issue arises when the specified module cannot be found or accessed, hindering the program's functionality. Resolving import errors is crucial for maintaining smooth software operation and uninterrupted development processes.
This presentation was provided by Steph Pollock of The American Psychological Association’s Journals Program, and Damita Snow, of The American Society of Civil Engineers (ASCE), for the initial session of NISO's 2024 Training Series "DEIA in the Scholarly Landscape." Session One: 'Setting Expectations: a DEIA Primer,' was held June 6, 2024.
Pollock and Snow "DEIA in the Scholarly Landscape, Session One: Setting Expec...
Molecular cell take home 1
1. Stephen Corvini
Take Home Test
Molecular Cell Biology
Dr. Bettica
November 25, 2011
Question #1:
The human red blood cell is a great example for studying protein-membrane function
interactions because these are simple cells in which the membrane is a crucial component. Red blood
cells act primarily as means of transportation within the body and their integral membrane proteins
work the regulate gas, ion and other substance transport between the internal and external
environments of the cell. Spectrin maintains the structural integrity of the cell membrane of the
erythrocyte. It forms a movable mesh network that allows for lateral movement of protein components
within the inter-membrane layer. Band 4.1, adducin, and tropomysin contribute to the determination of
actin filament length. Band 3 appears to acts as a channel protein within the membrane. Band 4.1 works
with ankyrin in order to form structural complexes within the membrane as well.
In regard to constraint of lateral movement within the membrane, Band 3 is constrained and
this appears to be regulated by ankyrin and protein 4.1. These proteins are attached to the mesh
network of 100nm spectrin filaments within the membrane. Spectrin is flexible and as a result allows for
the lateral movement of molecules. Band 3 is a component of junctional complexes in the membrane
and as a result does express some physical constraints in its overall lateral mobility.
If a red blood cell were deficient in spectrin and was lacking proper spectrin as a result, there
would be a highly negative impact on the lateral movement of Band 3. This protein relies on spectrin
and the flexible mesh network that it maintains in order to achieve a proper degree of lateral mobility.
Band 3 is mostly constrained by spectrin and if this protein were not sufficiently bound to Band 3 it is
possible there would be an uncontrolled degree of lateral mobility which would negatively effect the
molecular transport function of the membrane as well. Without proper spectrin binding there would be
uncontrolled movement of Band 3. Spectrin holds Band 4.1 and ankyrin in place around Band 3 and this
would be absent with improper spectrin binding. This would result in the improper constraint of Band 3.
Corvini 1
2. There are many methods which are used to isolate extrinsic and intrinsic proteins from the cell
membrane. Detergents are chemical substances that are used in order to isolate specific proteins. Ionic
detergents such as sodium dodecyl sulfate (SDS) and nonionic detergents, such as octylglucoside are
used to treat various protein types. All detergents remain monomeric in low concentrations and do not
readily effect the proteins that are present within the cell environment. It is only when they are present
in strong/critical amounts that they will form globular molecules known as micelles and work to break
down the membrane environment so that various proteins can be purified.
Ionic and nonionic detergents have various advantages and disadvantages. Nonionic detergents
can readily isolate functional protein molecules. This allows them to be studied. Ionic usually render
most proteins inactive and must be removed in order to reinstate functionality of these molecules.
Conversely, ionic detergents can solubilize the most hydrophobic proteins. Ionic detergent isolated
proteins cannot be used for studies because they have lost their functionality. Nonionic detergents allow
for collection of proteins that can be used for studies, but these detergents are not necessarily capable
of solubilizing all membrane types.
Question 1A:
In order to characterize the integral protein composition I would choose a proper detergent. For
purposes of this scheme, sodium dodecyl sulfate (SDS) would be effective. This would solubilize the
membrane portion surrounding the lysosome. I would then utilize a mixture of phospholipids and
incorporate them with the detergents allowing for a phospholipid molecule to be created that would
hopefully capture the desired protein. The detergent SDS would be removed; thus allowing the integral
protein of the lysosomal membrane to be successfully purified.
Question 1B:
I would analyze the purified protein through SDS polyacrylamide-gel electrophoresis. This would
expose the hydrophobic core of the protein. Through comparison with the hydrophobic cores of other
isolated proteins from the lysosomal membrane I could confirm it was a member of that particular
membrane type. This would help rule out its possibility for being a contaminant from other parts of the
cell.
Corvini 2
3. Question 2:
An N-linked oligosaccharide is one that is added to the NH2 group of an asparagines amino acid
within a protein. These are added within the lumen of the Endoplasmic Reticulum. They don’t act on
cytosol located proteins. This molecule is important for the process of protein glycosylation. The O-
linked oligosaccharides are added to the hydroxyl group which forms a side chain on the amino acid
serine, hydroxylysine, or threonine. This type of protein glycosylation occurs within the lumen of the
Golgi Apparatus. In general the N-linked are longer than the O-linked.
The enzyme oligosacchyral transferase catalyzes the transfer of oligosaccharides to the target
functional group with which the sugars most commonly bind. Prior to this transfer a precursor
oligosaccharide is modified before attaching to the components of the proper receptor protein. They are
prepared for synthesis when they are added to a carrier lipid dolichol molecule. Glucose, mannose, and
N-acetylglucosamine represent the different categories of N-linked oligosaccharides.
Once essential lysosomal enzymes are recognized by the mannose 6-phosphate receptor they
must be transported to the lysosome. The hydrolases bind to the MP6 receptor and receive a clathrin
coat. This forms a receptor dependent vesicle through the process of endocytosis. This vesicle is then
ejected from the trans-terminal end of the Golgi Apparatus. They bind to the lysosome where the acidic
pH dissociates the vesicle and delivers the hydrolase successfully. Phosphates are removed from the
hydrolase and the enzyme is incorporated into the lysosome.
Modifications of N-linked oligosaccharides occur within the lumen of the Endoplasmic
Reticulum. This is where they are added as well. Transfer of N-linked sugars happens with help of
oligosacchyral transferase on the luminal side of the Endoplasmic Reticulum membrane. O-linked sugars
are added and modified within the lumen of Golgi Apparatus. They undergo similar modifications and
additions as do the N-linked sugars, but are less common. Only about 10% are usually O-linked sugars.
Corvini 3
4. Question 2A:
I-cell disease patients exhibit a series of molecular symptoms. Normally, most hydrolytic
enzymes are missing from lysosomes, undigested substrates accumulate and this forms inclusions which
are very large within cells. This disease is due to a single gene defect and as a result can be considered
hereditary in nature. Hydrolases are missing from lysosomes in the blood as well. This is because they
are secreted rather than properly transported to their lysosome receiving cells.
Question 2B:
LDL proteins work to bind to specific LDL receptor proteins at a specific binding site. The
mannose 6-phosphate is contained in the area where the binding of multiple LDLs begins to form the
membrane of the transport vesicle known as the clathrin coat. Areas known as clathrin pits exist as this
structure forms and play a direct role in its construction. Adaptor proteins enclose the components of
the coat of the vesicle. The vesicle will contain M6P receptors and the desired enzymes. Endocytosis
ejects the vesicle which is released in coated form. It is uncoated and becomes a vesicle. It then fuses
with the endosome which separate hydrolases and LDL components. Hydrolases are then sent to
awaiting lysosomes and LDL components returned to cell membrane in a recycling endosome which
binds to them back into the original cell membrane.
Question 2C:
The mannose 6-phosphate molecules are normal because they are not directly effected by the
pH. Within the cell environment pH is maintained by an ATP driven-pump. The more basic pH may not
be high enough to successfully dissolve the membrane of the transport vesicle. Also, it is possible that
the LDL receptors are binding to the endosome, but not being successfully ingested. The binding of the
LDL may be enough to signal the release of the M6P molecules. Also, the pH may still be high enough to
degrade the vesicle membrane enough to allow M6P release. It is most likely that the LDL receptors will
not be properly recycled as they are in the normal pathway due to the nature of the mutant LDL cell
components.
Corvini 4
5. Question 3:
RTKs directly phosphorylate specific tyrosines on themselves and on a small set of intracellular
signaling proteins. They have two domains which usually consist of a cysteine rich domain connected to
a tyrosine-kinase domain. These regions are connected by a disulfide-bridge that passes through the
plasma membrane. There are various growth factor receptors that are linked to the tyrosine-kinase
domains. These molecules can also have immunoglobulin-type-III-like domains as well.
RTKs function in cell-signaling. Ligands, predominantly various extracellular proteins bind to
RTKs and transducer a variety of different signal processes throughout the inner environment of the cell.
Ephrins are among these ligands that bind to EpH receptors. Binding causes a shift in the conformational
shape of the transmembrane alpha-helix region specifically. This allows transmembrane proteins to
transmit signals by activating the respective kinase region.
RTKs work with extracellular binding proteins and receptor proteins which are located internally
within the cell. Ligand binding causes receptors to become dimerized which allows for the activation of
the kinase region. This results in the successful phosphorylation of tyrosines. The activation of these
molecules is vital to cell signal transduction. Once activated intracellular signaling proteins, particularly
those with SH2 domains such as Insulin and platelet derived growth factors work with RTKs.
The Src Homology 2 domain (SH2) allow for binding of various ligands to kinase regions. SH2
domains contain phosphotyrosine binding domains which allow for proteins that have these regions to
bind to RTKs and transmit intracellular signals.
The Ras protein acts as a signal center for a variety of signals. They contain monomeric GTPases
and serve to relay signals from cell surface receptors.
In the mechanism where epidermal growth factor (EGF) binds to its RTK receptor, Ras serves as
the in-between “switch” that triggers for emission of the signal by this mechanism. These nonionic
GTPases work to bind and relay signals from their respective RTKs. Essentially, they act as the middle
man between the initiating and terminal factors of a signal-transduction pathway.
Corvini 5
6. The Src Homology 3 domain (SH3) specifically binds to proline rich amino acid sequences. It is a
type of interaction protein and is very similar to that of SH2, except it possesses its own unique function.
The Rho family of Ras proteins serve to regulate the progression of the cell cycle. They function
specifically on various cytoskeletal elements which may be important during the cell cycle. They play a
central role in gene transcription and membrane growth. These molecules are most likely involved in the
issuing of signals that trigger progression past specific checkpoints of the cell cycle as well. It is involved
in the PI-3 kinase Akt pathway by acting as the primary signal transducer for this pathway which results
in production of molecular components need to prevent the occurrence of apoptosis, or cell death.
When considering oncogenic cells within the body there is an error that exists within the
functionality of RTK binding that leads to continuous proliferation. Mutant forms of these genes do not
encode for the normal amount of binding and as a result there is a difference in the signal cascade that
is issued into the intracellular cytosol environment. This overrides important checkpoints within the
cell’s growth cycle and causes for continuous signaling.
In the mechanism for transcription steroids, EGF, cAMP, and interferons play individually
important roles. Primarily, cAMP serves to activate kinases through the energy transferring process of
phosphorylation. Steroids often bind to the active kinase regions of RTKs and take part in the
transduction of intracellular signal cascades. EGF is needed to stimulate cell growth, production, and
signaling. Interferons increase resistance of cells to viral infection and also propogate greater
macrophage proliferation. All of these components work together to ensure the factors for initiation of
transcription are generated while working to preserve a safe environment in which these molecular
processes can occur.
Question 4:
Topsoisomerase I produces a transient single strand break within the DNA backbone. By
breaking the phosphodiester bonds it allows two sections of the DNA helix to rotate freely and swivel
around the cut area as a point of reference. This serves to relieve tension that may exist within the
Corvini 6
7. structural make up of the DNA helix. Topsoisomerase II creates a double strand break within the double
helix. This molecule works on areas where two strands of DNA have overlapped and become tangled in a
sense. It is necessary to untangle these strands because this situation causes a great amount of steric
strain on the backbone of the DNA. By cleaving the double helix at this region the strain caused by
supercoiling is greatly reduced. Topsoisomerase II is located predominantly in proliferating cells. Also,
topsoisomerase II is not part of special structure. It is a functioning enzyme that works in tandem with
the DNA double helix.
Question 4A:
The average number of base pairs per turn of the DNA double helix would be ten. The value of W would
be -65.
L=T+W
L–T=W
500 – 565 = W
W = - 65
Question 4B:
Topsoisomerase I would need to nick the original supercoiled molecule five times in order to reduce the
linking number as described (to a value of – 60).
L=T+W
L = 565 + (-60)
L = 505
Corvini 7