Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biomolecules Of Life > Proteins & post-translational modifications > Flashcards

Proteins & post-translational modifications Flashcards

1
Q

Why is the polypeptide chain flexible yet conformationally restricted

A
  • shape of AA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Explain how the amino acid backbone is polarised

A

H - bonding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Define the alpha helix

A

spatial arrangement of AA near each other in the linear sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe the bonding of alpha helix

A
  • hydrogen bonding (making it polar)
  • regular right-handed helix (R groups stick outwards)
  • every 4th peptide amino group + carbonyl group align with each other
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Why are RH helix more energetically favoured

A
  • proteins aim to get the lowest energy state
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are binding proteins

A
  • help DNA regulate cells reprocess including transcription
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is proline

A
  • stops the formation of alpha helix as no hydrogen atoms are bound to nitrogen
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are beta sheets

A

h-bonds between adjacent strands stabilising structures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Why is the antiparallel bonding more stable

A

h-bonding not distorted

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What can be the shape of beta sheets due to the polypeptide backbone

A

they aren’t in one flat plane and are twisted

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is a function of beta sheets

A
  • it can create high tensile strength
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Define the tertiary structures of proteins

A

spatial arrangemnt of AA usually far apart from each other in primary sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Define the quaternary structures of proteins

A

spatial arrangement of a protein made uno from more than 1 polypeptide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What do quaternary structures aid in

A

formation of larger proteins and structures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the allosteric effect

A

the binding of a ligand can affect the function or conformation of another protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Define acetylation and the enzyme used in the process

A
  • addition of methyl group at the N-terminal AA (alpha)
  • acetyltransferases ( transfers acetyl form co-enzyme A)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the different types of acetylation

A
  1. N-terminal acetylation
  2. Histone acetylation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is N-terminal acetylation

A
  • helps builds acetyl groups on on AA
  • protects from degradation and and increase the half life
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is histone acetylation

A
  • acetylation of lysine residues in histone proteins
  • reduces net +ve chsarge between histones and DNA leading to more open conformation and more transcriptional activity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is histone deacetylases

A
  • remove modifications leading to closed nucleosome conformation with no transcriptional activity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Describe hydroxylation

A
  • Addition of OH group
  • 2 residues are hydroxylated
    1. proline
    2. lysine
  • hydroxylation or organic compounds converts hydrophobic molecules into hydrophilic molecules
22
Q

Why is hydroxyproline important ion collagen

A

involved in H-bonding of the collagen fibres aiding in structural stability

23
Q

What enzyme is needed to convert proline and name any additions

A
  • propyl hydroxylase
  • ascorbic acid (vitamin C) as a cofactor
24
Q

Describe glycosylation and where does it take place

A
  • attachment of sugar molecules to specific residues In proteins making them more soluble
  • lumen of ER and Golgi apparatus
25
Q

What are the different types of glycoylstion

A
  1. N-glycosylation
  2. G - glycosylation
26
Q

What is N -glycosylation

A
  • Attachment of preformed complex carbohydrates (oligosaccharides) molecules to the nitrogen of an asparagine residue
27
Q

What is G -glycosylation

A
  • Attachment of sugar to O group of threonine and serine
  • no characteristic sequence involved
28
Q

Describe phosphorylation

A
  • a phosphate group derived form ATP is attached to proteins
29
Q

What enzymes regulate phosphorylation

A
  • kinases add
  • phosphatases remove
30
Q

What re protein kinases

A
  • highly selective targeting particular resides in certain proteins (no large scale activation)
31
Q

Define protein cleavage

A

process by which specific peptide bond between AA residues are hydrolysed

32
Q

What enzymes perfumes protein cleavage

A

proteases

33
Q

What are the 3 groups proteases can fall under

A
  1. Metalloproteases (contain metal ion)
  2. Serine proteases (contain critical serine residues)
  3. Aspartyl proteases (contains critical aspartic acid in active site)
34
Q

Describe an example of Metalloproteases

A

Carboxypeptides
- digestive enzyme found in gut
- cleaves off last C-terminal residue from chain
- functions between Val,Leu,Ile & Ala

35
Q

Describe an example of Serine proteases

A

Chymotryposin
- digestive enzyme found in gut
- cleave peptide chain on the carboxyl Side of aromatic large hydrophobic residues

36
Q

Describe an example of Aspartyl proteases

A

HIV protease
- chop up remain soft polypeptide chinas that cleave itself out out of large chains produced from the viral genetic material

37
Q

What are pre -proteins

A
38
Q

What are pro-proteins

A
39
Q

Describe the structure of keratin

A
  • long
  • large proportion of sulphur and cysteine = disulphide bridges
  • tough
40
Q

Explain the process of perming

A
  • Ammonium thioglycolate reduces the disulphide links to thiol so the hair strands can be separated
  • curling reorients the strands and thiol group
41
Q

Explain how to revert a perm back

A
  • Neutraliser H2O2
  • H2O2 oxidises some of the adjacent thiol groups to disulphide links to fix new orientation of the hair strands
  • it disrupts the weak bonds
42
Q

Describe the structure of collagen

A
  • long fibrous protein
  • triple superhelix (tropocollagen)
  • every 3rd AA is glycine
43
Q

Describe the chemical components of collagen

A
  • key AA = cysteine
  • no H-bonds within the strand instead between the strands
  • glycine is localised to the interior of helical bundles
44
Q

What is osteogenesis the cause

A
  • brittle bone disease
  • every 3rd AA in collagen is glycine
45
Q

What are fibroblasts

A

collagne producing cells

46
Q

Explain why we scar

A

collagen orientation in scars are parallel to epithelial surface unlike normal skin

47
Q

Why is hydroxyproline essential in collagen

A

modifications of the proline residue increases the stability of the collagen triple helix

48
Q

What does glycosylation of hydroxyproline in Y position do to the collagen molecule

A

makes the OH face outwards which is important for assembly, secretion and interactions

49
Q

How is collagen further stabilised

A
  • supported by chaperone proteins the collagen protein undergoes further processing and maturation in the Golgi apparatus
50
Q

What does the N & C terminal cleavage result in with collagen

A

removes the signal peptide

Biomolecules Of Life (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions