1.3 Proteins

Tania Parvaiz
Flashcards by Tania Parvaiz, updated more than 1 year ago
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AS level AS Biology (Unit 1 - Biological Molecules) Flashcards on 1.3 Proteins, created by Tania Parvaiz on 03/01/2017.
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What are proteins used for? (4) •Form cell structures •Form enzymes •Form chemical messengers •Form blood components
What are proteins made up of? Monomers (single units) called amino acids which have been joined together
What structure do all amino acids have? ca4feede-993f-4685-8d72-480ee7e31cfa.jpg (image/jpg)
What differs between amino acids? R group
What is a dipeptide? Two amino acids joined together
What is a polypeptide? More than two amino acids joined together
What bond is formed when amino acids join together during a condensation reaction to release a water molecule? A peptide bond (C-N)
How is a peptide bond formed? OH from carboxyl group and H from amino group taken out to form H2O molecule.
What are the 4 types of sequences of amino acids? •Primary •Secondary (alpha-helix and beta-sheet) •Tertiary •Quaternary
What is a proteins shape very specific to in the primary sequence? The proteins function
What are the weak bonds in the secondary structure known as and what do they do? Hydrogen bonds - cause long chain to be twisted
What are the 3 bonds in a tertiary sequence and what do they do? •Disulfide bridges - relatively strong and not easily broken •Ionic bonds - formed between any carboxyl and amino groups not involved in forming peptide bonds. Weaker than disulfide and easily broken by changes in pH •Hydrogen bonds - numerous but easily broken
What do quaternary structures consist of? Several polypeptide chains
What are the 2 protein groups which proteins can be grouped into and give examples of both? •Fibrous proteins (E.g: collagen and keratin) •Globular proteins (E.g: haemoglobin and enzymes)
Where is each type of protein located? •Fibrous: hair, nails & bones, cartilage •Globular: blood, cells and glands
Description of structure of fibrous proteins? Consists of long parallel polypeptide chains held together by cross-links and are twisted and tightly bound
Description of structure of globular proteins? Spherical compact shape caused by tightly folded polypeptide chains. Chains are folded with hydrophobic groups on the outside and hydrophilic groups on the inside.
Properties of fibrous proteins? Form strong, long rope-like fibres
Properties of globular proteins? Soluble in water and compact
Function of fibrous proteins? Provides structural support
Function of globular proteins? Transport oxygen
What 3 things can denature a protein? Change in... •Temperature •pH •Salt concentration
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