B1.2 - proteins

Question 1

proteins

Answer 1

Complex macromolecules composed of one or more chains of amino acids

Question 2

amino acids

Answer 2

Monomers used to make proteins

NH2 (amino group)
H (hydrogen atom attached to central carbon)
R side chain
COOH (carboxyl group)

Question 3

bonding + reactions of amino acids in protein

Answer 3

Amino acids join together by condensation reaction
Peptide bond formed when the carboxyl group (–COOH) of one amino acid reacts with the amino group (–NH2) of another amino acid to form a dipeptide

n terminal, c terminal

Question 4

role of proteins

Answer 4

catalysis, signalling pathways, structural support

Question 5

word equation of amino acids to create dipeptide

Answer 5

amino acid + amino acid → dipeptide + 1 water molecule

Question 6

essential amino acids

Answer 6

amino acids that your body CANNOT produce.
Obtain from food

Question 7

non-essential amino acids

Answer 7

produced by body from other amino acids/ breakdown of proteins

Question 8

genetic code

Answer 8

set of rules specifies how info in DNA is translated into sequence of amino acids

universal language of all living things

Question 9

transcription

Answer 9

DNA —> mRNA

Question 10

translation

Answer 10

mRNA —-> sequence of amino acids

Question 11

codon

Answer 11

group of 3 nucleotides that specify type of amino acid/ stop signal required

Question 12

genetic code is degenerate

Answer 12

multiple codons (64) can code for the same amino acid (20)

allows for silent mutations!!

Question 13

peptide bond

Answer 13

covalent/stable bond between carboxyl group of one amino acid to amino group of the other amino acid

Question 14

lets add another amino acid to the chain

Answer 14

n-terminal NOT involved in peptide bonds, new amino acids are added to the c-terminal

Question 15

list examples of polypeptides

Answer 15

lysozyme, alpha-neurotoxins, glucagon, myoglobin

Question 16

lysozymes

Answer 16

enzyme composed of 129 amino acids

tears and saliva

antimicrobial properties (disrupts cell wall)

Question 17

How do extremes of pH impact the structure of a protein?

Answer 17

It denatures the protein by changing the 3D conformation

Question 18

haemoglobin

Answer 18

• 4 polypeptide chains
• conjugated protein
• binds to oxygen
• 4 subunits held by h-bonds

Question 19

denaturation of protein (2 factors)

Answer 19

pH and temp (breaks weak h-bonds)

Question 20

conjugated protein
(definition + example)

Answer 20

contains non-protein components (metal ions, carbohydrates)

ex. haemoglobin

Question 21

non-conjugated proteins

Answer 21

contains only polypeptide subunits

ex. insulin, collagen

Question 22

alpha-neurotoxins

Answer 22

polypeptide

• 60-75 amino acids
• snake venom
• targets nervous system

Question 23

glucagon

Answer 23

polypeptide
- hormone

• 29 amino acid residues
• regulates blood sugar lvls
• secreted from pancreas

Question 24

myoglobin

Answer 24

polypeptide
- oxygen binding protein

• 153 amino acids
• muscle tissues
• storage and release of oxygen to muscle fibres (used in physical activity)

Question 25

R-groups (properties)

Answer 25

- hydrophobic/ hydrophilic - hydrophobic are non-polar, repels water - hydrophilic are polar, contains partial charges basic (+) acidic (-)

Question 26

primary structure of proteins

Answer 26

refers to specific sequence of amino acids joined together to form polypeptide chains - determines how the chain will fold (3D shape!)

Question 27

secondary structure of proteins

Answer 27

refers to local folding patterns that occur within the polypeptide chain - alpha helices - beta-pleated sheets

Question 28

alpha helices

Answer 28

- hydrogen bonds form between amine hydrogen of one amino acid and carboxyl oxygen of another amino acid 4 residues away in the sequence - allows coiling

Question 29

beta-pleated sheets

Answer 29

- sections of the polypeptide run parallel - h-bonds form between adjacent strands

Question 30

tertiary structure of proteins

Answer 30

further folding (interactions + bonding between R groups) H-bonds, ionic bonds, disulfide covalent bonds, hydrophobic interactions

Question 31

hydrogen bonding (tertiary)

Answer 31

- between polar R groups - stabilizes 3D shape (holds distant regions tgt)

Question 32

ionic bonding (tertiary)

Answer 32

- R groups go through binding & dissociation of H+ ions to create charged R groups

Question 33

disulfide covalent bonds (tertiary)

Answer 33

- forms between pairs of cysteine (contains sulfur)

Question 34

hydrophobic interactions (tertiary)

Answer 34

- occur between non polar amino acids - cannot interact with water, so they clump tgt in clusters in the inside of proteins

Question 35

globular proteins (+ example)

Answer 35

- spherical, irregular folds - soluble - enzymes, transporters, regulators ex. insulin, myoglobin

Question 36

fibrous proteins (+ example)

Answer 36

- long, narrow - stability for skin, tendons, bone ex. collagen

Question 37

quaternary structure of proteins

Answer 37

- arrangement/ interaction of 2 or more polypeptide chains

Question 38

insulin

Answer 38

- hormone regulating amount of glucose in the body - produced by pancreas - binds to receptors of the cell, allowing glucose to enter) - compact and GLOBULAR - hydrophobic exterior, hydrophilic interior

Question 39

collagen

Answer 39

- most abundant protein in the body (forms connective tissues + skin, cartilage) - made of 3 polypeptide chains twisted in a triple helix - fibrous protein - contains glycine and proline residues