Imms

Question 1

What is the rate limiting enzyme in the Krebs (Citric acid) cycle?

Answer 1

Isocitrate dehydrogenase

Question 2

What does karyotype mean?

Answer 2

The number and appearance of chromosomes in a cell.

Question 3

What are the letters used to denote the arms of a chromosome and what are they separated by?

Answer 3

Long arm (q).
Short arm (p).
They are separated by a centromere.

Question 4

What form is DNA in when not in replication?

Answer 4

Chromatin.

Question 5

What is the name of densely packed chromatin?

Answer 5

Heterochromatin.

Question 6

How does genetic variation occur as a result of meiosis?

Answer 6

1. Independent assortment in metaphase 1 and 2.

2. Genetic recombination in prophase 1.

Question 7

How is gametogenesis different in males and females?

Answer 7

Males:
Some mitosis in embryo but mainly when reach puberty.
After meiosis 2 there are four equal sized gametes.
Females:
‘Oogonia’ formed in embryo.
Divides into 1 egg and 3 smaller polar bodies.
Meiosis 2 only happens if fertilisation occurs.

Question 8

What is lyonisation?

Answer 8

The process of X chromosome inactivation.

Question 9

What is non-disjunction?

Answer 9

failure of chromosome pairs to separate - resulting in either trisomy or monosomy depending on the phase of meiosis.

Question 10

What is gonadal (germline) mosaicism?

Answer 10

When precursor germline cells are a mixture of two or more genetically different cell lines.

Question 11

What type of disease is most common in developed countries?

Answer 11

Multifactorial (genetic + environmental),

Question 12

In what type of cell can golgi apparatus be clearly seen?

Answer 12

Plasma cells.

Question 13

What is a pinocytotic vesicle?

Answer 13

A vesicle that carries particles dissolved in liquid.

Question 14

What do peroxisomes do?

Answer 14

Contain enzymes that oxidise long-chain fatty acids for the cell to produce 2 carbon fragments for metabolism (beta oxidation). Produce AND breakdown hydrogen peroxide.

Question 15

True or false: the cytoskeleton can be seen on light microscopy.

Answer 15

False.

Question 16

Are most sugars in living organisms in the D or L optical arrangent?

Answer 16

D - and if there is no letter in front of the sugar, assume this is the case.

Question 17

What are oligosaccarides?

Answer 17

3-12 monosaccharides joined by O-glycosidic bonds.

Question 18

What is a proteoglycan?

Answer 18

Long unbranched polysaccharides radiating from a core protein (found in animals).

Question 19

Are most amino acids in living organisms in the D or L optical arrangement?

Answer 19

L - in contrast to sugars.

Question 20

What is super-secondary structure?

Answer 20

A combination of secondary structures, usually a combination of alpha and beta units.

Question 21

Describe the structure of haemoglobin.

Answer 21

Globin ( a protein that is made of four subgroups: 2 alpha, 2 beta) which surrounds four haem groups (a porphyrin ring with an fe2+ ion in the middle).

Question 22

Which way does DNA polymerase read DNA?

Answer 22

Polymerase reads the TEMPLATE strand from 3 to 5, so the new DNA synthesised from 5 to 3.

Question 23

What is a primer and why is it needed?

Answer 23

A short strand of RNA that acts as the start point for DNA synthesis as DNA polymerases can only add nucleotides to an existing strand of nucleotides.

Question 24

What does single strand binding protein (SSB) do?

Answer 24

Keep the two strands of DNA apart while synthesis of new DNA occurs.

Question 25

What are Okazaki fragments?

Answer 25

Short DNA pieces formed on the lagging which are later joined to make a full strand.

Question 26

What are the start and stop codons?

Answer 26

Start: AUG. Stop: UGA, UAG, UAA.

Question 27

How does primary mRNA become mature mRNA?

Answer 27

The mRNA is spliced to remove the introns, leaving just the exons.

Question 28

Describe the genetic code (3 features):

Answer 28

Degenerate, Universal (almost), non-overlapping.

Question 29

Is an in frame or out frame deletion worse?

Answer 29

Out frame - one base deleted as opposed to whole codon, so a frame shift will occur, which can be catastrophic.

Question 30

What is anticipation in genetics?

Answer 30

Where a disease caused by repeats, e.g. Huntington's, has earlier and more severe symptoms in progressive generations.

Question 31

What are the FOUR types of chemical communication?

Answer 31

1. Autocrine - cell releases chemical effects same cell. 2. Paracrine - adjacent and near cells effected (extracellular fluid). 3. Endocrine - secretion into blood. 4. Exocrine - secretion into ducts.

Question 32

Are peptide or steroid hormones faster?

Answer 32

Peptide - minutes vs steroid's hours or days.

Question 33

What are the causes of insensible losses of water in the body?

Answer 33

Sweat, breath, vomiting and faeces.

Question 34

What is the measure of number of dissolved particles per kg of fluid?

Answer 34

Osmolality.

Question 35

What causes the release of renin (3) and where is it released?

Answer 35

A decrease in renal perfusion pressure/ reduced nacl in distal tube detected by macula densa cells/ sypathetic stimulation, causing juxtaglomerular kidney cells to release renin.

Question 36

Where is angiotensin converting enzyme found?

Answer 36

Renal endothelium, the lungs and capillary endothelium.

Question 37

What are the 4 types of receptors:

Answer 37

1. Ligand gated ion channels. 2. G-protein coupled receptors. 3. Enzyme linked receptors. 4. Intracellular (nuclear) receptors.

Question 38

Define basal metabolic rate:

Answer 38

The amount of energy needed to keep the body alive in the rest state.

Question 39

What percentage of ATP production do lipids account for at rest?

Answer 39

70%.

Question 40

How do large (> 12 carbons) fatty acids pass through the mitochondrial membrane?

Answer 40

A two stage process know as the carnitine shuttle.

Question 41

Why are fatty acids not used as a fuel source for the central nervous system?

Answer 41

Because they cannot pass through the blood brain barrier.

Question 42

What happens when excess acetyl CoA is produced?

Answer 42

The liver (hepatocytes) start the process of ketogenesis which produces ketone bodies.

Question 43

Why does diabetic ketoacidosis occur?

Answer 43

Due to the lack of sugar regulation in the blood, more fatty acid oxidation will occur and more ketone bodies will be produced, exceeding the capacity of the peripheral tissues. They will then build up in the blood, lowering the pH.

Question 44

What is the main reason that ketoacidosis is bad?

Answer 44

It impairs the ability of haemoglobin to bind to oxygen.

Question 45

Why do patients with diabetic ketoacidosis have sweet (pear-drop) smelling breath?

Answer 45

Acetoacetate can be converted to acetone which is volatile and can be expired via the lungs.

Question 46

Describe the Fenton reaction:

Answer 46

Reaction of hydrogen peroxide with an iron ion to form a hydroxyl radical. H2O2 + Fe2+ -> OH- + OH*

Question 47

Describe the Haber-Weiss reaction:

Answer 47

O2*- + H2O2 + H+ -> O2 + H2O + OH*

Question 48

What is the most potent ROS.

Answer 48

The hydroxyl radical (OH*).

Question 49

What is the rate limiting enzyme of glycolysis and what is it inhibited by?

Answer 49

Phospofructokinase-1 - inhibited by ATP and citrate.

Question 50

What is the rate limiting enzyme of the krebs cycle?

Answer 50

Isocitrate dehydrogenase.

Question 51

What protects white blood cells from their own respiratory burst?

Answer 51

Catalase - converts hydrogen peroxide into water and oxygen.

Question 52

What is a strong acid?

Answer 52

An acid the ionises completely in solution.

Question 53

What is the normal pH range of the body?

Answer 53

7.35-7.45.

Question 54

What is the most important buffer system in the body?

Answer 54

Carbonic acid and bicarbonate.

Question 55

Apart from bicarbonate, what are two other buffer systems are there?

Answer 55

Protein buffers and haemoglobin.

Question 56

What is the Henderson-Hasselbach equation?

Answer 56

pH = pKa + log([HCO3-]/{CO2]).