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S3- Proteins Flashcards

1
Q

What is collagen?

A

Major structural protein (25% of total body’s protein) in the extra cellular matrix, resilient sheets to support skin and internal organs, molecular cables for tendons, bones and teeth

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2
Q

Bones and teeth are made by adding….to collagen

A

Hydroxy-apatite crystals (dash for pronunciation)

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3
Q

What is the primary structure of collagen protein?

A

Repeated sequence of 3 amino acids: Glycine-X-Y-Gly-X-Y
Forming a secondary alpha chain

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4
Q

The X and Y amino acids in the collagen primary structure are frequently…..

A

Proline and it’s modified version hyrdoxyproline

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5
Q

The 3 levels of collagen structure are…

A

Triple helix= 3 alpha chains
Collagen fibrils= cross-linking
Collagen fibre= packing

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6
Q

There are at least…types of collagen and have different…and different alpha chains combinations therefore…

A

12
Functions
Quaternary structure

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7
Q

The most common types of collagen are….and they form long….

(Fibril-forming collagen)

A

I, II, III
long fibrils (fibril-forming)

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8
Q

Type I collagen is..% of total collagen and is the main component of….

It is found in….,…,…but not in….

It is used in….

A

90%
Bone
Skin, hair, tissue
Cartilage
Tissue repair

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9
Q

Type II collagen is the main component of….and is found in the…..and…

A

Cartilage
Cornea
Vitreous humour

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10
Q

Type III collagen combines with type….and it’s found in…with…properties/ hollow organs such as…..

A

Type I
Tissues
Elastic
Skin, arteries, muscle, lungs, intestine (organs that stretch)

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11
Q

(Network forming collagen)
Type IV and VI collagen form a….which is important in the…..

A

2-dimensional matrix
Basal lamina (epithelial cells)

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12
Q

The specialised cells that make collagen (according to their location in the body) are called….

A

Fibroblasts = encode different alpha chains that will form different collagen molecules

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13
Q

Collagen mRNA goes from nucleus to RER, then Golgi then exocytosis to leave cell, what are the 6 steps of collagen production?

A

In RER = preprocollagen
1. Pro alpha chain backbone (Gly-X-Y)
2. Hydroxylation of proline and lysine (requires vitamin C)
3. Glycosylation
Procollagen (triple helix structure)
4. Exocytosis
Outside cell (the ends of the chains are still not wrapped around each other- so they just get cut later)
5. Cleavage of procollagen C and N terminals = form tropocollagen
6. Formation of cross-links (stabilised by lysyl oxidase)- copper dependent

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14
Q

Hydroxylation of proline and lysine forms…and the enzymes….are used

The reaction requires….to assist addition of oxygen from our diet

A

Hydroxyproline and hydroxylysine
Prolyl hydroylase and lysyl hydroxylase

Vitamin C

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15
Q

Proline hydroxy: stability of….due to extra…

Lysine hydroxy: stability of the…due to extra….

A

Triple helix, H bonds
Fibrils, cross linking

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16
Q

The cross linking of collagen uses the enzyme….which uses….as a cofactor

A

Lysyl oxidase
Copper

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17
Q

Extracellular matrix collagen have no….in fibril but rather very…layers to allow soft tissues (unlike bones and teeth)

A

Crosslink
Loose

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18
Q

What happens to collagen in old age?

A
  • more cross0linking= more brittle and less elastic
  • synthesis decreases
  • bones more easily broken (brittle)
  • arteries and skin less elastic
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19
Q

Aging or disease causes….which harms the damages the tissues and its functions

A

Fibrosis (thick/ stiff tissue scarring/ over-growth/ hardening and is attributed to excess deposition of extracellular matrix components like collagen)

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20
Q

Collagen is one of the….in fibrotic tissues

A

Upregulated genes (increased rate)

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21
Q

4 pathologies of collagen are:

A
  1. Osteogenesis imperfecta= mutations in collagen chains
  2. Scurvy= lack of vitamin c in diet= less hydrocylation
  3. Menke’s disease= copper deficiency
  4. Ehlers-Danlos syndrome type VI= lysyl oxidation deficiency
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22
Q

Osteogenesis imperfecta in known as….
It is caused by….(no family history/ genetic disorder)
Its severity increases with ….
Sometimes it is mistaken for….

A

Brittle bone disease
Spontaneous mutation
Substitution by large and charged amino acids (they prevent triple helix forming tight/ stable/ sturdy structure= loose= bones easily broken)
Child abuse

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23
Q

Osteogenesis imperfecta types, protein, defect, phenotype, sclera, life-expectancy

A

Type I= alpha 1 collagen/ collagen quantity/ mild non-deforming/ blue/ normal age
Type II= alpha1 and 2/ collagen structure/ perinatal lethal/ blue/ perinatal
Type III= 1and2/ collagen structure/ progressively deforming/ blue than normal/ childhood
Type IV= 1and2/ collagen structure/ moderately deforming/ normal eyes/ slight reduction in age

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24
Q

Scurvy is triggered by lack of…(vit C) which prevents….
Therefore collagen is not stabalised (less H bonds between alpha chains and less cross-linking)

A

Ascorbic acid
The enzyme activity of proline and lysyl hydroxylases

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25
The main symptoms of scurvy are…. Around 200 cases of death in UK in 2022 due to….
Loss of teeth and easy bruising (lack of collagen to repair wear and tear by everyday activities) Malnourishment
26
Menke’s disease are….and… They are caused due to mutation in a…. Without treatment, life expectancy is…
Rare and X-linked Copper transporter 3 years
27
Ehlers-Danlos has more than…types due to mutations in at least 20 genes found Many of these genes are responsible for making collagen, others make….
20 Proteins that process, fold, or interact with collagen
28
Collagen has 3…handed helix chains that have…residues per turn These combine to form…handed triple helix
Left 3.3 Right
29
In collagen helix structure, proline and hydroxyproline are on the….to max…. Small…residues are packed into the…
Outside, hydrogen bonds Glycine, centre
30
Collagen 1 is made of 2….chains and 1….chain
Alpha 1 Alpha 2
31
Oxygen is….in blood and needs a transport system ….is for O2 and CO2 transport ….is for O2 storage
Sparingly soluble in blood Haemoglobin Myoglobin
32
Haemoglobin is the…that makes blood red Its composed of 4….and 2…and 2… Oxygen binds….
Protein Protein chains Alpha and beta (each has haem group with iron atom) Reversibly
33
Haem is male of…
Fe2+ and proto-porphyrin IX
34
Hb chain has very similar….to Mb but differs at…of amino acid residues
3D structure 83%
35
Oxygen binding…tertiary and quaternary structure of Hb because binding to one subunit affects…with other subunits, which makes binding of next O2….
Alters Interactions Easier
36
Mb has greater…for O2 than Hb, so its good for….
Affinity (binding) Storage function
37
Binding of O2 to Hb is….and the binding curve is…
Co-operative Sigmoidal (s shaped)
38
Haem enables transport of other molecules like:…
Nitric oxide, carbon monoxide
39
Nitric oxide affects…which… It binds to specific…and…
Walls of blood vessels= relax/ vasodilation= reduce blood pressure Cysteine residues in Hb and Fe in haem group
40
Carbon monoxide is a…which binds…to haem It causes…deaths each year Symptoms include:…
Toxic gas Irreversibly (better than O2) 60 Nausea, dizziness, confusion
41
Structure of amino acid? Basic amino acid has…. Acidic amino acid has…. At neutral pH they exist as… The nature of amino acid side chain/ R group determines…
Amine/ amino group NH2- carbon+H+R group- carboxyl group COOH NH3+ (accepts H+= basic) O- (donates H+= acidic) Zwitterion Its properties
42
The 4 types of amino acid groups are…
1. Electrically charged side chains (acidic and basic) 2. Polar uncharged side chains 3.special cases 4. Hydrophobic side chains
43
Peptide is….linked by… The bond is…
1+ amino acids Peptide bond/ amide bond Very chemically stable/ planar (between HN and O)
44
Each amino acid unit on polypeptide is called…
Residue
45
Primary structure is… It defines how the protein will… Single change in amino acid structure can cause…
Linear sequence of amino acids Fold and function Disease
46
Secondary structure of protein has…and forms….such as….and…
H bonds Stable structural elements Alpha helix Beta sheets
47
What determines the possible confirmations/ shapes/ structure of polypeptides?
Bond length and bond angle
48
Alpha helix has a…structure with….bonds …residues per turn
Coiled Intrachain H bonds (within a chain) 3.6
49
Beta sheets are stabilised by…. The chains can…by making…
Hydrogen binds between strands Change direction Reverse turns and loops
50
To function, proteins….to form a…structure They create a…or…to hold a substrate Two or more chains bind to give a….and form a….structure
Fold into compact, globular shape Tertiary structure Pocket or active site Functional molecule, quaternary structure
51
The 5 interactions/ bonding that is holding the tertiary and quaternary proteins together are…
1. H bonds= (between H atoms) covalently bound to proton donor and acceptor 2. Ionic= charged amino acids, often surface exposed on outside 3. Disulfide= between cysteine residues 4. Van der waals= weak electrostatic forces of attraction 5. Hydrophobic interactions= between hydrophobic residues often on the inside of proteins
52
5 types of protein functions:
1. Structural= cytoskeletal 2. Regulatory= chaperones 3. Carriers= membrane transporters 4. Catalytic= enzymes 5. Sensory= receptors
53
Protein misfolding results in….and it can be driven by…
Disease Change in primary sequence or escape from negative folding pathway
54
Prion diseases are…. Can originate through…or… Caused by accumulation of…
Fatal neurodegenerative diseases Transmission or inheritance Prion protein aggregates
55
Misfolding of amyloid protein results in…with…
Formation of fibrils Cross-beta structure that cannot be degraded
56
Amyloid beta are associated with….
Alzheimer’s disease
57
Hb vs Mb
Hb= allosteric, co-operative, affinity changes by pH and CO2, regulated by biphosphateglycerate Mb= non co-op, not affected by pH, CO2 or BPG
58
The 2 states of Hb
R state= relaxed= less salt bridges between units= high affinity of O2 T state= tense= more salt bridges= low affinity of O2 (de-oxy state since no O2 is bound)
59
Hb in lungs vs tissue Loading and unloading
Lungs= lots of O2= high affinity so more O2 bind to Hb Tissue= less O2= low affinity so more O2 released When one O2 release= protein changes shape promoting the 3 other to quickly release/ when one O2 binds (hardest to bind)= protein changes shape so its easier for the rest to bind
60
Bohr effect= Hb has less affinity for O2 when:
PH is lower/ more H+/ due to increased CO2 or lactic acid in blood (to promote fast release of O2 to tissue and muscle quickly)
61
Why do H+affect O2 binding
PH affects protonation state of amino acid residues (particularly histidine)= H+ conc is high= residues protonated= more positively charged Form new salt bridges= stabilise T state (more tense due to increases salt bridges= decrease affinity for O2)
62
2,3- BPG is…and is found at high conc in… The structure of BPG is..charged It…affinity of O2 BPG levels are…at high altitude and under…conditions This means Hb releases…O2 in these 2 situations
2,3- Biphosphateglycerate RBC Negatively (phosphate groups are negative) Decreases Increased, hypoxic (lack of O2 in tissue) More
63
BPG binds in the space between…so HbF… Negative charges of BPG interact with..
Beta chains Is not affected by BPG Positive amino acid residues
64
H+, CO2 and BPG interact at….sites So their effects can be…
Different Additive
65
HbF has…than HbA It pro-dominates during last 2….and by end of fist year our body makes entirely…
Higher affinity to O2 Trimesters of gestation HbA
66
HbA vs HbF
1. Both have 4 subunits 2. 2 identical alpha subunits 3. HbF= 2 gamma subunits (instead of beta) 4. Gamma increases affinity for O2 5.no beta chains= no 2,3-BPG binding 6. BPG reduces affinity in HbA= so under same conditions, HbA will release O2 and HbF will capture it
67
How do mutations affect haemoglobin:
1. Amount of Hb synthesised 2. Structure (ie subunit interfaces) 3. Stability of Hb= leading to haemolytic anaemia 4. Affinity for O2 5. Affinity for regulators (ie BPG)
68
Types of position mutations in Hb:
Position (mutations in critical residues will affect function ie: promoter region/ exon splice site/ protein structure) Types: 1. Conservative= maintains properties (non-polar replaced with non-polar residue) 2. Non-conservative= changes properties
69
2 haemoglobinopathies (opathies= disease suffix)
1. Sickly cell anaemia (affects Hb structure) 2. Beta-thalassaemia (affects Hb production)
70
Sickly cell heamoglobin=… Is caused by…
HbS Mutation in beta-globin chain (beta chain subunit)= (B6 Glu is replaced by Val)
71
HbS makes…patches in subunit surface and it… They stick together to form…that distort shape of RBC= sickle
Sticky hydrophobic Sticks to another hydrophobic patch Long fibres
72
Sickly cell crisis occurs when… It lasts for… Other symptoms are… Its treated by…
Sicked RBC becomes trapped within small blood vessels and block them= damage organs 7 days Tiredness, headaches, dizziness, increased infection risks Fluids, painkiller, antibiotics, transfusions (no cure)
73
Sickle cell anaemia is an… Sickle cell trait=… It occurs more in geographical areas with…as it gives a…against malaria
Autosomal recessive disease Carrier= one copy of mutated beta globin High incidence of malaria Protective effect
74
HbF can be a…to sickle cell because it… As…% of HbF in blood reduces the symptoms …therapy is researched to increase level of HbF …anticancer drug that is shown to be effective as it increased HbF levels
Solution Lacks beta chains 20 Gene therapy (surpresses a silencer of HbF gene= more is expressed) Hydroxyurea
75
Thalassaemia effects…and its caused by… The severity depends on… Less Hb=…
Production of haemoglobin Reduction or absence of alpha or beta chains Type Less HbS= less sickling

IMS 1 (14 decks)

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