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Principles MBCHB > Biochemistry > Flashcards

Biochemistry Flashcards

(65 cards)

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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
Whats is the function of **primase?**
Synthesizes short RNA sequences that are complementary to a single-stranded piece of DNA, which serves as its template.
26
Whats is a promoter?
* Is a very specific sequence of nucleotides within the DNA (which act as a binding site for very specific proteins and for RNA Polymerase)
27
What is a **tata** box?
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
What needs to happen to mRNA before translation can occur?
* **SPLICING** * **Processing the ends of the mRNA**
29
What happens during splicing?
he process through which the **non-coding regions (introns)** of the mRNA are removed, leaving only the **coding regions (exons).**
30
What happens during the processing of ends of mRNA?
* Addition of poly(A) tail * Addition of 5’ cap
31
What is a polysome?
* a complex of a mRNA molecule and two or more ribosomes that is formed during active translation.
32
_Ribosomes_ in the **_cytoso_**l make proteins destined for.....
— Cytosol — Nucleus — Mitochondria
33
Bound _ribosomes_ on the _RER_ make proteins destined for...
— Plasma membrane — ER — Golgi apparatus — Secretion
34
When does DNA replication occur??
S phase
35
What is a polymorphism
•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
Unbalanced chromosome rearrangement
Extra or missing chromosomal material. Usually 1 or 3 copies of some of the genome.
37
What diease is caused by TRISOMY 18
Edward Syndrome
38
45 X
Turner Syndrome
39
47 xxy
Klinefelter syndrome
40
Describe microfilaments
are composed of the protein actin
41
Describe Intermediate filaments
are composed of six main proteins, which vary in different cell types.
42
Describe Microtubules
are composed of two tubulin proteins.
43
What is the perinuclear cisterna
the space separating the inner from the outer nuclear membrane.
44
Describe type 1 diabetes
Little/no insulin secretion Defect in Beta cell function Ketosis develops (if untreated) Insulin injections for treatment Symptoms develop rapidly
45
Describe type 2 diabetes
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
Describe the genetics of twins
**Monozygotic** twins share all their genes **Dizygotic** twins share 50% of their genes
47
Name some models of **_Non-medelian inheritance patterns_**
- Epigenetic Modifaction of DNA - Mitochondrail Inheritance - Somatic Mosaicism
48
What is **DNA methylation?**
- 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
List 5 hormones that influence [glucose]p.
1. Insulin 2. Glucagon 3. Adrenaline 4. Cortisol 5. Growth Hormone
50
Explain the changes in plasma glucose, insulin and glucagon concentrations with time after a meal.
**Glucose** and **Insulin** _both rise_ after a meal whilst **glucagon** levels _drop._
51
Describe the major physiological actions of insulin
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
Explain how insulin lowers [glucose]p.
- 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
Explain how diabetes mellitus may be detected
ORAL GLUCOSE TOLERANCE TEST
54
Know what stimulates glucagon release from pancreatic alpha cells.
STIMULATION: Decreased blood glucose Amino acids Sympathetic nerve activity
55
Know what inhibits glucagon release from pancreatic alpha cells.
INHIBITION: Raised blood glucose Insulin
56
Explain how glucagon raises [glucose]p.
GLUCAGON RAISES [GLUCOSE]p by: Increasing liver glycogenolysis. Inhibiting liver glycogen synthesis. Promoting liver gluconeogenesis. also promotes lipolysis in liver and adipose tissue.
57
Explain the role of growth hormone in providing glucose during prolonged fasting.
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
What is the Nucleus tractus solitarius
* 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
What is special about succinate dehydrogenase in the TCA cycle?
It is located in the mitochondrial membrane **_NOT_** the matrix!
60
Control point in gycolysis. Name 3 enzymes catalysing irreversible reactions.
Hexokinase – substrate entry . Phosphofructokinase – rate of flow Pyruvate Kinase – product exit
61
What is the warburg effect?
Cancer cells produce energy by high rate of glucose metabolism to lactate
62
What enzyme catalyzes Glucose-6-phosphate --\> Glucose-1-phosphate
Phosphoglucomutase
63
What is DNA replication catalysed by?
DNA Polymerase
64
What enzyme unwinds DNA ?
Helicase
65
What are the 3 ways treating cancer by targeting gycolsis?
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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