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Principles MBCHB > Biochemistry > Flashcards

Biochemistry Flashcards

1
Q

Phosphorylation & De-phosphorylation

A

Addition/Deletion of a phosphate group [PO4-]

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2
Q

Describe Acylation

A

Addition of acyl group to compound

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3
Q

Explain carboxylation…

A

a chemical reaction in which a carboxylic acid group is introduced in a substrate

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4
Q

Describe esterification

A

2 products come together (alcohol and carboxylic acid) to form an ester

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5
Q

describe a hydrolysis reaction

A

water is used to break a polymer onto two smaller monomers

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6
Q

name the 5 oxidation states of carbon

A

alkane > alcohol > aldehyde > Carboxylic acid > CO2

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7
Q

what is the first law of thermodynamics?

A

Energy is neither created or destroyed

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8
Q

what is the second law of thermodynamics

A

when energy is convwrted from one form to another, some of it becomes unavailable to do work ( as reactions are not 100% efficient)

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9
Q

What is an exergonic reaction

A

reactions in which the total free energy of the products is less than the total free energy of the reactants

.: ΔG = -ve
Reaction can occur spontaneously and the energy released can be used to do work

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10
Q

What is an endergonic reaction?

A

Reactions in which the total free energy of the product(s) is more than the total free energy of the reactant(s)

.: ΔG = +ve
Such reactions cannot occur spontaneously and they need an input of energy to proceed

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11
Q

What is ATP

A
  • 𝑨𝑻𝑷 + 𝑯𝟐𝑶 → 𝑨𝑫𝑷 + 𝑷(𝒊) + 𝑯!
  • Many reactions occur in the body by coupling unfavourable reactions (∆𝐺 = +ve) with the above

hydrolysis.

  • ATP is thus used as a universal energy currency.
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12
Q

What is catabolism?

A

breaking down complex molecules into smaller ones and releasing

energy (exergonic – oxidation)

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13
Q

what is anabolism

A

is synthesizing complex molecules out of smaller ones in energy- consuming reactions (endergonic – reduction)

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14
Q

What is a micelle?

A

The formation of a micelle is a response to the amphipathic nature of fatty acids, meaning that they contain both hydrophilic regions (polar head groups) as well as hydrophobic regions (the long hydrophobic chain).

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15
Q

What is special about the amino acid GLYCINE?

A

it has no stereoisomers

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16
Q

Name the 4 sub groups of amino acids…

A

1) Non-Polar, Hydrophobic Amino Acids
2) Polar, Uncharged Amino Acids
3) Acidic Amino Acids
4) Basic amino acids

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17
Q

What is the direction of a peptide bond?

A

You have a repeating chain of

  • alpha-carbon -> carboxy- carbon -> amino nitrogen
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18
Q

what is a zwitterion?

A

Amino acids without charged side groups (no net charge)

(will have to PKa values)

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19
Q

What is a Nucleoside

A

have a 5-carbon sugar + a base

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20
Q

What is a nucleotide

A

5-carbon sugar + a base + one or more phosphate groups

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21
Q

What is transfer RNA?

tRNA

A

Transfer RNA become covalently linked to amino acids.

They act as transducter molecules to bring amino acids to growing protein chain (and ribosome)

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22
Q

Name the three types of eukaryotic ploymerase?

A
  • Pol I
  • Pol I
  • Pol III
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23
Q

How can polymerases be distinguisged?

A

By their sensitivity to toxins like α-amanitin (which is derived

from a fungus) – inhibits Pol II but doesn’t inhibit Pol I or Pol III

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24
Q

What happens in cells that cannot divide

A

Still produce gene products via gene expression

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25
Q

Whats is the function of primase?

A

Synthesizes short RNA sequences that are complementary to a single-stranded piece of DNA, which serves as its template.

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26
Q

Whats is a promoter?

A
  • Is a very specific sequence of nucleotides within the DNA (which act as a binding site for very specific proteins and for RNA Polymerase)
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27
Q

What is a tata box?

A

Is found in all promoters that are recognised by RNA Pol II. It tells the Pol II where to start transcribing and in which direction.

28
Q

What needs to happen to mRNA before translation can occur?

A
  • SPLICING
  • Processing the ends of the mRNA
29
Q

What happens during splicing?

A

he process through which the non-coding regions (introns) of the mRNA are removed, leaving only the coding regions (exons).

30
Q

What happens during the processing of ends of mRNA?

A
  • Addition of poly(A) tail
  • Addition of 5’ cap
31
Q

What is a polysome?

A
  • a complex of a mRNA molecule and two or more ribosomes that is formed during active translation.
32
Q

Ribosomes in the cytosol make proteins destined for…..

A

— Cytosol
— Nucleus
— Mitochondria

33
Q

Bound ribosomes on the RER make proteins destined for…

A

— Plasma membrane

— ER
— Golgi apparatus
— Secretion

34
Q

When does DNA replication occur??

A

S phase

35
Q

What is a polymorphism

A

•Any variation in the human genome that does not cause a disease in its own right. It may however, predispose to a common disease

36
Q

Unbalanced chromosome rearrangement

A

Extra or missing chromosomal material. Usually 1 or 3 copies of some of the genome.

37
Q

What diease is caused by TRISOMY 18

A

Edward Syndrome

38
Q

45 X

A

Turner Syndrome

39
Q

47 xxy

A

Klinefelter syndrome

40
Q

Describe microfilaments

A

are composed of the protein actin

41
Q

Describe Intermediate filaments

A

are composed of six main proteins, which vary in different cell types.

42
Q

Describe Microtubules

A

are composed of two tubulin proteins.

43
Q

What is the perinuclear cisterna

A

the space separating the inner from the outer nuclear membrane.

44
Q

Describe type 1 diabetes

A

Little/no insulin secretion

Defect in Beta cell function

Ketosis develops (if untreated)

Insulin injections for treatment

Symptoms develop rapidly

45
Q

Describe type 2 diabetes

A

Insulin secretion may be normal (or exceed normal)

Defect in insulin sensitivity

Ketosis rare

Diet/exercise and oral drugs for treatment

Symptoms develop slowly

46
Q

Describe the genetics of twins

A

Monozygotic twins share all their genes

Dizygotic twins share 50% of their genes

47
Q

Name some models of Non-medelian inheritance patterns

A
  • Epigenetic Modifaction of DNA
  • Mitochondrail Inheritance
  • Somatic Mosaicism
48
Q

What is DNA methylation?

A
  • Usually occurs on cytosine bases just before guanine bases
  • DNa methylation leads to modification of histones this represses transcription

PREVENTS TRANSCRIPTION

Every cancer methlates genes

49
Q

List 5 hormones that influence [glucose]p.

A
  1. Insulin
  2. Glucagon
  3. Adrenaline
  4. Cortisol
  5. Growth Hormone
50
Q

Explain the changes in plasma glucose,

insulin and glucagon concentrations

with time after a meal.

A

Glucose and Insulin both rise after a meal whilst glucagon levels drop.

51
Q

Describe the major physiological actions of insulin

A

INSULIN:

Favours anabolism.

Stimulates conversion

of glucose into glycogen,

fatty acids into triglycerides

and amino acids into protein.

Insulin is the hormone of the fed-state.

52
Q

Explain how insulin lowers [glucose]p.

A
  • Stimulating the uptake of glucose

from the blood into muscle and fat cells.

  • Activating the enzymes in liver

and muscle which convert glucose into glycogen.

  • Insulin also promotes the incorporation

of amino acids into protein

in muscle and promotes lipogenesis in - adipose tissue

53
Q

Explain how diabetes mellitus may be detected

A

ORAL GLUCOSE TOLERANCE TEST

54
Q

Know what stimulates glucagon release from pancreatic alpha cells.

A

STIMULATION:

Decreased blood glucose

Amino acids

Sympathetic nerve activity

55
Q

Know what inhibits glucagon release from pancreatic alpha cells.

A

INHIBITION:

Raised blood glucose

Insulin

56
Q

Explain how glucagon raises [glucose]p.

A

GLUCAGON RAISES [GLUCOSE]p by:

Increasing liver glycogenolysis.

Inhibiting liver glycogen synthesis.

Promoting liver gluconeogenesis.

also promotes lipolysis in liver and adipose tissue.

57
Q

Explain the role of growth hormone in providing glucose during prolonged fasting.

A

Not normally important in control of [glucose]p

BUT in response to starvation,

growth hormone:

Decreases glucose uptake by muscle – “glucose sparing” action

Mobilises glucose from liver

also promotes lipolysis in fat cells

58
Q

What is the Nucleus tractus solitarius

A
  • is site of 1st synapse for all CVS afferents in the medulla
  • relays information to other regions in the brain e.g. medulla, hypothalamus, cerebellum

Generates vagal outflow to heart

59
Q

What is special about succinate dehydrogenase in the TCA cycle?

A

It is located in the mitochondrial membrane NOT the matrix!

60
Q

Control point in gycolysis.

Name 3 enzymes catalysing irreversible reactions.

A

Hexokinase – substrate entry .

Phosphofructokinase – rate of flow

Pyruvate Kinase – product exit

61
Q

What is the warburg effect?

A

Cancer cells produce energy by high rate of glucose metabolism to lactate

62
Q

What enzyme catalyzes

Glucose-6-phosphate –> Glucose-1-phosphate

A

Phosphoglucomutase

63
Q

What is DNA replication catalysed by?

A

DNA Polymerase

64
Q

What enzyme unwinds DNA ?

A

Helicase

65
Q

What are the 3 ways treating cancer by targeting gycolsis?

A
  1. 2-deoxy-glucose block further metabolism of g6p
  2. 3 bromopyruvate competitive inhibitor
  3. Di-chloroacetate stops cells from growinng

Principles MBCHB (6 decks)

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