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FBS1 > Cell Biology > Flashcards

Cell Biology Flashcards

1
Q

Groups at beginning and end of a polypeptide

A

First: NH3+ Last: COO- group.

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2
Q

Groups binding in disulfide bridges

A

Two cysteine groups (either from 2 different polypeptides or 2 on the same)

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3
Q

Mechanism of methylation in proteins

A

NH2 groups of lysine and Argenine

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4
Q

Secondary structure of protein bonds

A

Alpha helix: hydrogen bond between O and H of same polypeptide . 3.6 residues Beta pleated sheets: hydrogen bond between different polypeptides. Polypeptides can be parallel or antiparallel.

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5
Q

Bonds in the collagen triple helix

A

H bonds between 3 chains forming a triple left handed helix. Between glycine, proline and hydroxy proline.

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6
Q

Example of protein with high B sheers and properties

A

Fibrillation proteins - high tensile strength, no elasticity

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7
Q

Forces that stabilize protein structures (1 covalent, 4 non covalent)

A

Hydrogen bonds, electrostatic interactions, vander waals forces, hydrophobic effect Disulfide bridges

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8
Q

Why proteins can denature easily

A

Low amount of stabilization energy from all of the different interactions

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9
Q

Induced fit model of enzymes

A

Enzyme and substrate combine to change the shape of the substrate, so that it is more unstable and ready to change.

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10
Q

Reaction of lactate dehydrogenase

A

Pyruvate fo lactate using 1NADH and H+

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11
Q

Oxidoreductase enzyme example and function

A

Lactate dehydrogenase Transfer of H atoms and electrons

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12
Q

Transferase example and function

A

Alanine aminotransferase Catalyze transfer of functional groups

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13
Q

When is Km equal to the substrate concentration in the Michael Menton equation?

A

When the reaction velocity is at half of its maximum (ie. when V= Vmax /2)

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14
Q

What is the meaning of Km

A

The smaller km value, the higher the affinity between substrate and the enzyme

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15
Q

Meaning of Kcat

A

How many molecules of of substrate get converted to product by the enzyme in a given amount of time at saturated substrate concentration.

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16
Q

In the lineweaver Burke plot, 1/ Vmax is the…

A

Y intercept

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17
Q

In the lineweaver Burke plot, -1/Km is the…

A

X intercept

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18
Q

How malonate works as a competitive inhibitor

A

Competes with succinate for active sites of succinate dehydrogenase

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19
Q

How competitive inhibitors later km and vmax

A

Km: they increase km (decrease substrate affinity) Vmax: no effect on max velocity of reaction

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20
Q

Effect of non competitive enzyme on km and Vmax

A

Km: no change because affinity for substrate does not change Vmax: decreases because max velocity decreases with non competitive inhibitor

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21
Q

Explain control of angiotensin production for heart disease as an example of clinical use of enzyme inhibitor

A

In heart disease where blood flow is reduced, excess angiotensin would be produced causing too much vasoconstriction and reabsorltion. ACE inhibitor can be used to stop the formation of angiotensin

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22
Q

Example of allosteric regulation of the fructose6 phosphate to fructose 1,6 biphosphate by phosphofructokinase

A

+ allosteric : AMP - allosteric : ATP and citrate

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23
Q

Covalent modification of enzymes example of when it promotes and inhibites an enzyme.

A

Promotes: glycogen phosphorylase phosphorylated by addition of phosphate to Serine Inhibited: glycogen synthase phosphorylated and hence deactivated by addition of phosphate to serine residue

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24
Q

Amino acid on which following covalent modifications occur: Adenylylation Uridylylation ADP-ribosylation Methylation

A

Adenylylation: tyrosine Uridylylation: tyrosine ADP-ribosylation: arg, gln, cys Methylation: glutamine

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25
Q

Protein activated in cAMP pathway

A

Adenyl cyclase

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26
Q

Reaction triggered by adenyl cyclase

A

ATP to cAMP

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27
Q

2 things PKA phosphorylated

A

Enzyme in cytoplasm and CREB, which regulates transcription

28
Q

First molecule activated by G protein in the inositol triphosphate pathway

A

Phospholipase C

29
Q

Action of phospholipase C

A

Inositol phospholipid into IP3 and DAG

30
Q

Action of IP3

A

Binds to endoplasmic reticulum and causes release of calcium

31
Q

Role of DAG

A

Binds with calcium to protein kinase C and activated protein.

32
Q

Receptor tyrosine kinase mode of action

A
  1. Two RTK bind to a ligand and come together to form a cross linked dimer. 2. Activated tyrosine kinase 3. Cross phosphorylation: the RTK phosphorylated the tyrosine of the other RTK. 4. Once phosphorylated, proteins containing an SH2 domain can bind to the tyrosine. 5. Protein gets phosphorylated
33
Q

Actin filaments

  1. associated proteins
  2. monomers
  3. structure
  4. assembly and dissasembly
A

Protein: actin binding proteins

Monomers: G-actin (globular actin)

Structure: Polarised double helix

  1. assembly: monomers added from both ends, faster on + end. Uses ATP to form and releases ADP when dissasembling
34
Q

Intermediate filaments

  1. associated proteins
  2. monomers
  3. structure
  4. assembly and dissasembly
A

Monomers: individual intermediate filament proteins

Structure: dense around nucleus, extending into the periphery

Assembly and dissasembly:

35
Q

Microtubules

  1. associated proteins
  2. monomers
  3. structure
  4. assembly and dissasembly
A
  1. microtubule associated proteins
  2. tubulin monomer (alpha and beta subunits)
  3. structure: one + one - side because of alpha and beta. long stiff hollow tubes. 13 colomns of tubulin
  4. uses GTP for assembly. From centrosome (negative) to periphery
36
Q

Example of actin filament

A

cilia in gut

37
Q

example of intermediate filament function

A

stabilize shape of axons

Meshwork around the cell nucleus to hold it in position

Cell junctions

38
Q

Example of microtubule function

A

Anchoring of organelles within the cell (RER, SER…)

DNA

39
Q

The steps of actin based movement

A

Cell pushes out protrusion at the front due to actin filaments polymerizing in that direction.

Protrusions of F-actin (filaments) adhere to the surface cell is moving through and the cell pulls against these anchorage points to move forwards, and actin depolymerizes at the back.

40
Q

How actin plays a role in lamellipodia or filopodia touching down on a surface

A

Actin creates the connection between focal adhesions (integrin-containing complexes connecting the cell to surface) and the rest of the cytoskeleton. Allowing for motility, transfer of info…

41
Q

How the microtubule-associated-protein, dyenin, plays a role (2) in movement.

How kinesin plays a role too.

A

It initiates the sliding along one another, causing cilia to bend and move stuff.

Kinesin and dyenin move vescicles along the microtubules (kinesin moves it towards + end periphery and dynein moves it towards - end nucleus).

42
Q

What is a processive motor protein and how it helps with the cycle

A

processive motor proteins like kinesin stay attached to the filament they are moving along (unlike myosin) so they can go for long distances.

43
Q

Examples of cytoskeleton related therapeutics

A

Chemotherapeutic agents that can destabilise microtubiles or stabilise them, inhibit cell division.

44
Q

How listeria bacteria hijacks the actin cytoskeleton

A
45
Q

Affinity for glucose of GLU-1 to 5

A
46
Q

How glut 4 is activated by insulin

A

Insulin causes translocation of glut 4 transporter to membrane, allowing for glucose uptake

47
Q

Max size of cell

A

50um

48
Q

How do specialised cells overcome issue of surface area

A

Giant multinucleated cells

thin processes (axons)

gap junctions

49
Q

Golgi apparatus what it does to carbohydrates and lipids and other functions

A

Modifies N-linked carbohydrates

Glycosylates O-linked carbohydrates and lipids

Creates lysosomes, transports lipids

50
Q

what do perixosomes do

What zellweger syndrome and adrenoleukodystrophy are in relation to perixosome

A

detoxification

phospholipid synthesis

Oxidation of very long chain fatty acids (VLCFA)

H2O2 degradation

Zelleweger: no perixosome

Adrenoleukodystrophy: affect protein that import VLCFA into perixosome

51
Q

Lysosome function

A

Hydrolises major cellular macromolecules, using low pH

52
Q

What is the anomeric carbon in a glucose ring molecule

A

The carbon attached to the original carbonyl group in cyclic form (linear structure)

53
Q

Alpha vs beta glucose

A
54
Q

Bond that binds to alpha glucoses

A

Alpha 1,4 glycosilic bond

55
Q

Reaction catalysed by lactase

Issue with undigested lactose

A

Lactose to galactose and glucose

If you don’t digest it, intestinal bacteria does and produces a lot of CO2 causing bloating and diahrrea

56
Q

Difference between ribose and deoxyribose

A
57
Q

Structure of nucleotide and DNA

A

DNA: sugar phosphate backbone. nucleotides boud by hydrogen bonds

58
Q

Structure of ATP

A
59
Q

Types of lipids and structure (4)

A

TAG: triglycerides have 3 fatty acid chains bount to a glycerol backbone via ester bonds. Used for energy storage

Fatty acids: Long chain C-H chains ending with carboxyl group. Can be saturated and unsaturated (double bond). Used for energy.

Phospholopids and glycolipids: glycerol + 2 FA and phospholipds also have phosphate containing group. Make up membrane

Steroids: multi ring structure (e.g. cholesterol). Used for hormones and membrane stability

60
Q

Basic structure of amino acid and bond

A

Peptide bond between C and N.

61
Q

Classify as polar or non polar

A
62
Q

Difference in membrane composition:

Plasma membrane

Outer/ inner mitochondrial membrane

Nuclear membrane

A
63
Q

Basic structure of a phospholipid

A

Polar head group can be serine, cholne, ethanolamine, inositol

64
Q

What is sphingomyelin and its structure?

A

Sphingomyelin: a membrane lipid mostly found in the myelin sheath of neurons. It is made up of 3 parts:

  1. one fatty acid chain (like in normal phospholipid)
  2. a sphingosine group
  3. phosphocholine polar head group

1 and 2 can be grouped as a ceramide

65
Q

Effect of the following on membrane fluidity:

Short chain fatty acids

A

Short chain fatty acids: increase fluidity (reduced interactions)

Unsaturated fatty acids: increase fluidity (reduced London forces)

Cholesterol: decreases fluidity (restricts movement of polar heads)

66
Q

Describe the following proteins as their type of interaction with the membrane and the bonds that secure these interactions

A

E.g. anchored membrane: alkaline phosphatase (bound to surface glycolipid) or RAS (fatty acyl anchored protein)

E.g. peripheral proteins: spectrin (interacts with membrane protein like ankyrin) and phospholipase A2 binds to bilayer to cleave fatty acids from phospholipids

67
Q

Action of phospholipase enzymes on the phospholipids

A

They free fatty acid tail from polar head at different points:

FBS1 (7 decks)

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