amino acids and proteins

Question 1

how many amino acids are building blocks for proteins in cells?

Answer 1

22

Question 2

describe the general structure of an amino acid

Answer 2

Amino group - N terminus end

Carboxyl group - C terminus end

R group

Question 3

what defines the chemical characteristics of the amino acid?

Answer 3

R

Question 4

In what ways can amino acids be classified based on chemical characteristics?

Answer 4

All about R group side chain

Polar

Non-polar

Charged

Non-charged

Aliphatic

Aromatic

Question 5

In which ways can amino acids be classified based on synthesis?

Answer 5

Proteinogenic

Non-proteinogenic

Question 6

In what ways can amino acids be characterised based on essentiallnes

Answer 6

essential
conditionally essential
non essential

Question 7

What makes an R group polar?

Answer 7

-OH group

C=O bond

Question 8

amino acids with ‘polar uncharged R groups” are characterised by what?

Answer 8

polar groups in the side chains, which can form hydrogen bonds. e.g -OH, -SH, -C=O and -NH2

Question 9

the amino acids with “aromatic R groups” are characterised by what?

Answer 9

an aromatic ring structure, which gives these amino acids there characteristic UV spectra

Question 10

the amino acids with “acidic R groups” are characterised by what?

Answer 10

the amino acids aspartate and glutamate, the negatively charged side chains can form electrostatic interactions with positively charged basic side chains

Question 11

the amino acids with “basic R groups” are characterised by what?

Answer 11

lysine, arginine and histidine, positive charged side chains

Question 12

the amino acids hydroxyproline and hydroxylysine are hydroxylated forms of what? what do they require for their synthesis?

Answer 12

• proline and lysine
• vitamin C as a co enzyme

Question 13

what is desmosine formed from?

Answer 13

4 lysine residues

Question 14

how do you know if amino acids are aliphatic?

Answer 14

only carbon and hydrogen in the side chain

Question 15

What are proteinogenic amino acids?

Answer 15

Building blocks of proteins

20 are encoded by triplets of the genetic code

Question 16

What is different about selenocysteine and pyrrolysine?

Answer 16

They both contain a structural change in the mRNA sequence allowing a STOP codon not to be recognised as such by a specific tRNA

Question 17

What are non-proteinogenic amino acids?

Answer 17

Don’t need to bind into a protein to exert their function.

e.g. GABA (neurotransmitter)

Carnitine (transport of fatty acids in the blood)

Question 18

How are non-proteinogenic amino acids produced?

Answer 18

• are not produced directly and I isolation by standard cellular machinery
• Occurring post-translationally, once the protein has already formed

Question 19

What are some common modifications of non-proteinogenic amino acids?

Answer 19

Phosphorylation

Methylation

Acetylation

Hydroxylation

Question 20

What are essential amino acids?

Answer 20

Cant be synthesised by the body so must be obtained through the diet

Question 21

What are conditional essential amino acids?

Answer 21

In condition of stress, a surplus of these amino acids need to be uptaken through the diet to cope with body demand

Question 22

What are non-essential amino acids?

Answer 22

Can be synthesised by the body

Question 23

What is an issue with herbivores consuming lots of hay/straw/haylage?

Answer 23

High levels of lignin, which reduces the absorption of nutrients. This decreases levels of essential amino acids such as Lysine

Question 24

What are some types of proteins in body?

Answer 24

Receptor

Contractile

Hormonal

Structural

Enzymes

Question 25

What are some functions of proteins in the body?

Answer 25

Protection Storage Structure Receptors Transport Enzymes Contractions Hormones

Question 26

What is primary protein structure?

Answer 26

Sequence of a chain of amino acids

Question 27

How do amino acids bind together?

Answer 27

Peptide (amide) bonds

Question 28

What type of chain is a protein?

Answer 28

polypeptide

Question 29

How does a peptide bond form?

Answer 29

dehydration synthesis reaction (condensation)

Question 30

What is secondary protein structure? What are the 2 types?

Answer 30

When hydrogen bonds form between amino acids α helix β pleated sheets

Question 31

Is an α helix hollow?

Answer 31

NO - just a spiral

Question 32

Is an α helix hollow?

Answer 32

NO - just a spiral

Question 33

What type of spiral is an α-helix?

Answer 33

Right-hand spiral

Question 34

How do α-helix spirals form?

Answer 34

Every backbone NH group donates a hydrogen bond to the backbone C=O group of the amino acid, located 3 or 4 residues earlier along the protein sequence

Question 35

What does a β structure contain?

Answer 35

β strands and β sheets

Question 36

What are β strands?

Answer 36

Portions of the polypeptide chain that are almost fully extended, having a zig-zag shape

Question 37

Are β strands flexible or elastic?

Answer 37

Flexible but not elastic

Question 38

Describe the structure of β strands

Answer 38

H-bonded β strands can be on separate polypeptide chains, or on different segments of the same chain β strands in a sheet can either be parallel or antiparallel

Question 39

How do β-sheets form?

Answer 39

When multiple β strands are arranged side by side, they form β sheets

Question 39

How do β-sheets form?

Answer 39

When multiple β strands are arranged side by side, they form β sheets

Question 40

How are β sheets stabilised?

Answer 40

Stabilised by hydrogen bonds between carbonyl oxygens and amide hydrogens on adjacent β strands

Question 41

What is tertiary protein structure?

Answer 41

- Occurs when certain attractions are present between alpha helices and beta-pleated sheets - spatial arrangement of atoms

Question 42

How is protein tertiary structure stabilised?

Answer 42

Numerous weak interactions: Hydrogen bonds Electrostatic interactions Hydrophobic interactions Disulfide bonds

Question 43

How is protein tertiary structure stabilised?

Answer 43

Numerous weak interactions: Hydrogen bonds Electrostatic interactions Hydrophobic interactions Disulfide bonds

Question 44

What are the 2 major classes of tertiary structure proteins?

Answer 44

Fibrous and globular

Question 45

Are proteins always either hydrophilic or hydrophobic?

Answer 45

Can be either depending on structure, or amphipathic

Question 46

What is protein quaternary structure?

Answer 46

When a protein has more than one subunit and sometimes other elements too

Question 47

Give an example of a quaternary protein

Answer 47

haemoglobin

Question 48

Describe the structure of haemoglobin

Answer 48

4 chains 4 subunits A non-protein heme group binding a Fe2+

Question 49

What is the function of haemoglobin?

Answer 49

Allows aerobic respiration by transporting O2 and CO2

Question 50

What causes mis-folded proteins?

Answer 50

Mutations in their amino-acid sequence Error in the folding process

Question 51

What 2 types of effect can protein misfolding have?

Answer 51

Loss of function and gain of function

Question 52

What 2 types of effect can protein misfolding have?

Answer 52

Loss of function and gain of function

Question 53

Give an example of an effect of protein mis-folding which is loss of function?

Answer 53

Cystic fibrosis

Question 54

Give examples of an effect of protein mis-folding which is gain of function?

Answer 54

Alzheimer's Parkinson's Huntington's

Question 55

What causes sickle-cell anaemia?

Answer 55

Mutation in haemoglobin

Question 56

What is the process of making RNA from DNA?

Answer 56

Transcription

Question 57

What is the process of making a protein from RNA?

Answer 57

Translation

Question 58

what do disulphide bonds consist of?

Answer 58

one cysteine residue

Question 59

how is the primary structure of a protein always written?

Answer 59

N->C terminal

Question 60

what structure is a a-helix?

Answer 60

secondary

Question 61

how many amino acids per tern of the helix are there in a a-helix

Answer 61

3.6

Question 62

the biological function of myoglobin is determined by the presence of a what?

Answer 62

heme (haem) group

Question 63

what bonds are formed between b-strands

Answer 63

hydrogen

Question 64

what amino acid does not have a chiral alpha carbon?

Answer 64

glycine

Question 65

what is the amino acid desmosine commonly found in?

Answer 65

elastin, a protein found in connective tissue