From genes to proteins. (A dummies guide for Unit 3 Biology) Source: http://library.thinkquest.org/C004535/protein_synthesis.html Ian Anderson – Saint Ignatius College, Geelong

Proteins. Proteins are macromolecules built up of amino acid monomers. They play a key role in living organisms. Each cell contains several hundred to several thousand proteins. They have specific structural and functional roles (human proteome estimated >100 000).

Proteins are macromolecules built up of amino acid monomers.

They play a key role in living organisms.

Each cell contains several hundred to several thousand proteins.

They have specific structural and functional roles (human proteome estimated >100 000).

Functional diversity of Proteins. amylase, lipase, lactase, trypsin Catalyze metabolic reactions (enzymes) Catalytic hemoglobin, myoglobin Act as carrier molecules Transport antibodies such as gammaglobulin Combat invading microbes Immunological myosin, actin Form the contractile elements in muscle (skeletal, smooth, cardiac) Contractile insulin, glucagon, adrenalin, human growth hormone, follicle stimulating hormone Regulate cellular function (hormones, cell signaling) Regulatory Collagen, keratin Form the structural components of tissues and organs Structural

Proteins. Everything a cell is or does depends on the proteins it contains. Source: http://www.weberweb.net/animalcells.htm

Everything a cell is or does depends on the proteins it contains.

Protein synthesis. DNA carries the sets of instructions in the chromosomes for every part of an organism, including the production of proteins. Proteins however are manufactured on ribosomes located in the cell cytoplasm. A method is therefore needed to transfer the information needed to build a protein from the DNA to the ribosomes.

DNA carries the sets of instructions in the chromosomes for every part of an organism, including the production of proteins.

Proteins however are manufactured on ribosomes located in the cell cytoplasm.

A method is therefore needed to transfer the information needed to build a protein from the DNA to the ribosomes.

Protein synthesis. DNA cannot leave the nucleus, so DNA stays in the nucleus and another molecule, acting as a messenger, carries the instructions from the DNA to the ribosomes. Proteins can now be manufactured by the ribosomes. This two stage process = protein synthesis.

DNA cannot leave the nucleus, so

DNA stays in the nucleus and another molecule, acting as a messenger, carries the instructions from the DNA to the ribosomes.

Proteins can now be manufactured by the ribosomes.

This two stage process = protein synthesis.

Protein synthesis. Two stages of protein synthesis Transcription Translation

Two stages of protein synthesis

Transcription

Translation

Transcription. Relevant segment of DNA unwinds forming two single strands. Free floating nucleotides in nucleus bind to one strand following the base pairing rule adenine  uracil (not thymine) cytosine  guanine Complimentary copy of DNA, called messenger RNA (mRNA), is formed.

Relevant segment of DNA unwinds forming two single strands.

Free floating nucleotides in nucleus bind to one strand following the base pairing rule

adenine  uracil (not thymine)

cytosine  guanine

Complimentary copy of DNA, called messenger RNA (mRNA), is formed.

Source: http://www.coolschool.ca/lor/BI12/unit6/U06L01.htm

Protein synthesis. mRNA then leaves the nucleus and travels into cytoplasm and attaches to a ribosome. The ‘message’ from the DNA can now translated.

mRNA then leaves the nucleus and travels into cytoplasm and attaches to a ribosome.

The ‘message’ from the DNA can now translated.

Translation. Each sequence of three bases on the mRNA is called a codon (triplet code) and codes for a particular amino acid. Amino acids are brought to the ribosomes by transfer RNA (tRNA) and linked in the correct sequence to the mRNA according to the triplet code. Amino acids then join together to form a polypeptide chain (the primary structure of a protein). Order of amino acids defined by the original DNA instructions.

Each sequence of three bases on the mRNA is called a codon (triplet code) and codes for a particular amino acid.

Amino acids are brought to the ribosomes by transfer RNA (tRNA) and linked in the correct sequence to the mRNA according to the triplet code.

Amino acids then join together to form a polypeptide chain (the primary structure of a protein).

Order of amino acids defined by the original DNA instructions.

Source: http://www.coolschool.ca/lor/BI12/unit6/U06L01.htm

Source: http://www.biochem.arizona.edu/classes/bioc471/pages/Lecture1/Lecture1.html