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Flashcards in Proteins Deck (30)
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1

monomer?

amino acids

2

chemicals?

C, H, O, N
some have sulfur

3

amino acid structure

look at notes

4

How is a dipeptide formed?

2 amino acids join together by a peptide bond in a condensation reaction where water is released

5

What happens in a hydrolysis reaction?

water is used to break the peptide bonds so a dipeptide breaks into amino acids

6

What is a protein made of?

proteins are made of 1 or more polypeptides

7

primary structure of proteins

- sequence of amino acids in a polypeptide chain
- peptide bonds only
- a change in one amino acid may change the structure of the whole protein

8

secondary structure of proteins

- hydrogen bonds form between nearby amino acids in chain making it automatically coil into an alpha-helix or fold into a beta-pleated sheet

9

tertiary structure of proteins

- further folding or coiling of chain
- more bonds form between different parts of the polypeptide chain
- it forms the final 3D structure for proteins with a single polypeptide chain

10

What is the tertiary structure responsible for?

- the shape of the active site in enzymes
- the shape of channels in channel proteins

11

quarternary structure of proteins

- the way 2 or more polypeptide chains are assembled together
- the cross-linking of 2 or more polypeptide chains
- forms the final 3D structure for proteins with more than 1 polypeptide chain

12

bonds in primary structure

peptide bonds only

13

bonds in secondary structure

peptide and hydrogen bonds

14

bonds in tertiary structure

- ionic bonds
- disulfide bonds
- hydrophobic + hydrophilic interactions
- Hydrogen bonds

15

Ionic bonds

attractions between negatively charged R groups and positively charged R groups.

16

Disulfide bonds

when 2 molecules of amino acid cysteine come close together, the sulphur atom in one cysteine bonds to the sulphur atom in another cysteine forming a disulfide bond

17

Hydrophobic and hydrophilic interactions

when hydrophobic R groups come close together in protein, they clump together. Hydrophilic R groups are more likely to be pushed to the outside affecting how the protein folds up in its final structure.

18

Hydrogen bonds

weak bonds between slightly positively charged hydrogen atoms in some R groups and slightly negative charged atoms in other R groups on the polypeptide chain

19

bonds in quarternary structure

- determined by tertiary structure of individual polypeptide chains being bonded together which allows it to be influenced by all bonds

20

globular proteins properties

- ball shaped
- hydrophilic R groups pushed outwards forming Hydrogen bonds with water causing hydrophobic and hydrophilic interactions making it soluble so easily transported in fluids

21

Examples of globular proteins

- haemoglobin
- insulin
- amylase

22

Haemoglobin

- carries oxygen around the body in red blood cells
- conjugated protein (protein with a non-protein group attached)
- each of the 4 polypeptide chains have a prosthetic group called Haem
- Haem contains iron which oxygen bind sto

23

Insulin

- hormone secreted by pancreas
- regulated blood glucose levels
- soluble so transports to the tissues where it acts via blood
- consists of 2 polypeptide chains held together by disulfide bonds

24

amylase

- enzyme that catalyses the breakdown of starch in digestive system
- made of a single chain of amino acids
- secondary structure has both alpha helix and beta pleated sections

25

Fibrous proteins properties

- insoluble
- long strands (rope-like fibres)
- strong
- fairly unreactive
- structural proteins

26

Examples of fibrous proteins

- collagen
- keratin
- elastin

27

Collagen

- in animal connective tissue (bone, skin, muscle)
- very strong molecule
- minerals bind to protein to increase its rigidity

28

Keratin

- in external structures of animals (skin, hair, nails, horns, feathers)
- flexible - in skin
- hard and rough - in nails

29

Elastin

- in elastic connective tissue (skin, large blood vessels, ligaments)
- elastic so allows tissues to return to their original shape after stretching

30

What is a conjugated protein?

- a protein with a non-protein group attached
- non-protein group is called a prosthetic group
- example is haemoglobin