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Medicine > MGD > Flashcards

MGD Flashcards

1
Q

What sort of binding does Myoglobin exhibit?

A

Hyperbolic

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2
Q

When do you see higher levels of 2,3 BPG and how does it effect Haemoglobin?

A

Increases in areas of high metabolism + at high altitude

Decreases Haemoglobins affinity for O2

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3
Q

What is the Bohr effect?

A

H+ and CO2 released during high metabolism bind to Haemoglobin and reduce its affinity for O2

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4
Q

What causes Sickle Cell Anaemia and what happens in it?

A

Caused by a single nucleotide substitution from Hydrophillic Glutamate -> Hydrophobic Valine
Sticky Hydrophobic pocket allows deoxygenated Hbs to polymerise and distort the shape of the RBC

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5
Q

What causes alpha + Beta Thalassaemia?

A

Decreased or absent Alpha or Beta chains

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6
Q

Whats the difference between Alpha + Beta Thalassaemia?

A

Beta - Alpha chains unable to form stable tetramers. After Foetal Haemoglobin goes they have growth problems, anaemia, jaundice, enlarged liver
Alpha - Beta chains can form stable tetramers with higher affinity for O2. Often show no signs or symptoms

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7
Q

What is Vmax?

A

Maximum rate of reaction when all enzymes active sites are filled with substrate

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8
Q

What is Km?

A

Substrate concentration that gives half of Vmax

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9
Q

How does the Km value reflect the affinity for the substrate?

A

The lower the Km the higher the affinity for the substrate

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10
Q

What does CO do?

A

Binds to Haemoglobin 250x more readily than O2. Increases affinity of other subunits for O2 so they dont release it at tissue

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11
Q

What is Allosteric regulation?

A

The binding of substrates to one subunit increases the affinity for substrates at other subunits

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12
Q

What is Proteolytic Cleavage?

A

Enzymes secreted as inactive precursors are cleaved to become active

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13
Q

What causes activation of the Intrinsic blood clotting pathway?

A

Damaged membrane of RBC’s promotes binding of factor XI to X

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14
Q

What causes activation of the Extrinsic blood clotting pathway?

A

Trauma releases tissue factor III which activates factor X

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15
Q

What causes Classic Haemophillia?

A

Defect in factor VIII

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16
Q

What is the name of the fragments made on the lagging strand of DNA when its replicated? Which enzyme joins the fragments together?

A

Okazaki Fragments

DNA Ligase

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17
Q

Which enzyme causes the unzipping and reforming of DNA during replication?

A

DNA Helicase

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18
Q

What 4 steps make up the Cell cycle?

A

G1- Cellular content is replicated
S - DNA is replicated
G2 - Checking phase
M - Mitosis

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19
Q

What are the 6 stages of Mitosis?

A

Interphase - Replication of DNA
Prophase - Chromosomes condense, Nuclear membrane breaks down, Spindle fibers form
Metaphase - Centrioles move to poles, Chromosomes line up along center
Anaphase - Chromosomes pulled apart
Telophase - Nuclear Membrane reforms
Cytokinesis - Cytoplasm divides

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20
Q

What is the difference between Genotype + Phenotype?

A

Genotype - Genetic make up of an individual

Phenotype - All observable characteristics of an individual as a result of their genetic make up

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21
Q

How is RNA synthesised in Transcription?

A

Initiation - Initiation code (TATA) is recognised, Transcription factors bind here (promoter region). RNA Polymerase is atracted
Elongation - RNA Polymerase travels along template strand from 3’->5’ picking up free nucleotides
Termination - Addition of Mythyl - Guannine cap to 5’ end to stabalise RNA. At 3’ end there is stop codon followed by a Poly A tail
Splicing - Introns removed by endonucleases

22
Q

What is the process of Translation in DNA replication?

A

Initiation - 40s Subunit binds to 5’ end of mRNA, start codon is 5’AUG. 60s Subunit then binds
Elongation - rRNA has P-site for holding peptide chain + A-site for accepting new tRNA. tRNA enters sA-site, forms peptide bind with tRNA in P-site, tRNA in P-site is then uncharged so leaves P-site
Termination - Requires a stop codon, no tRNA can bind to these codons

23
Q

What does it mean that the triplet code of DNA is degenerate? Why is this beneficial?

A

There is more than one code per amino acid

Means that not every mutation changes the primary sequence of DNA

24
Q

How is the active form of Insulin formed?

A

Synthesised as Preproinsulin,this contains signal sequence, C peptide, A+B peptides.
Signal sequence is removed from N-terminal by signal peptidase
3 disulfide bonds form - Proinsulin
Molecule cleaved into 3 peptides, C peptide released
A+B held together by 2 peptide bonds - Active Insulin

25
Q

What can be used to measure endogenous Insulin levels in diabetics?

A

C peptide released from Insulin production

26
Q

How are proteins targeted to the ER?

A

Signal sequence on N-terminal is recognised by Signal Recognition Protein + cleaved by Signal Peptidase
Protein is unfolded during transfer into the ER

27
Q

How are proteins targeted to the Nucleus?

A

Nuclear Localising Signal is found on the surface of the protein
Importin recognises NLS and mediates transport + transfer
Signal is retained so proteins can be reimported during nuclear reformation after cell division

28
Q

How are proteins targeted to Mitochondria?

A

Amphipathic signal for initial targeting to matrix (found on N-terminal) is cleaved
Protein is held partially unfolded by Mitochondria Import Stimulating Factor, TOM + TIM form the import channel

29
Q

How are proteins targeted to Lysosomes?

A

Mannose-6-Phosphate signal is added to N-linked Oligosaccharides in Golgi
M6P receptor of Golgi sends protein to lysosome, enters folded in vesicle
Vesicle + receptor return to Golgi

30
Q

How are proteins retained within the ER?

A

ER resident proteins have KDEL at C-terminus, if transported to Golgi KDEL receptors bind due to low pH and transport protein back to ER
Receptor dissociates from signal due to neutral pH and returns to Golgi

31
Q

How does Penicillin work?

A

Targets Bacterial cell wall by inhibiting Transpeptidase enzyme that forms cross links in cell wall

32
Q

How does Rifampicin work and what is it used to treat?

A

Targets bacterial RNA Polymerase, prevents mRNA synthesis so no translation + bacteria can’t divide
Used to tread TB, Leprosy, Staphylococcus, Meningitis

33
Q

How does Tetracyclin work and what is it used to treat?

A

Targets bacterial ribosomes, Binds to 30s subunit blocking the A site so tRNA can’t bind
Used to treat UTI, Gonorrhoea, Chlamydia, Pneumonia + eye infections

34
Q

In what ways can Antibiotic resistance occur?

A
  • Decreased influx of drugs by expressing a reduced number of carrier proteins
  • Increased Efflux of toxic products from the cep (Multi-drug resistance protein I)
  • Increased transcription of target to overwhelm the drug
  • Specific target of drug acquires a mutation lowering the affinity for it
35
Q

How does DNA sequencing by Sanger Dideoxy Chain Termination Method work?

A

Add fluorescent ddNTP’s (Dideoxynucleodie triphosphate) are added with regular dNTP’s to a DNA strand with DNA polymerase. ddNTP lacks a 3’ OH so terminates strand. Different strand lengths used to determine position of different nucleotides

36
Q

How does Restriction Analysis work?

A

Restriction endonucleases are bacterial enzymes that recognise specific sequences and cut them, this produces fragments that can then be analysed by gel electrophoresis

37
Q

How is Southern Blotting performed?

A

Unlabelled DNA from electrophoresis is transferred with nylon. DNA heated to 95 degrees to allow specific gene probes to bind. This can then be used to investigate gene structure

38
Q

How does Western Blotting work?

A

Primary antibody is added and binds to protein of interest. Secondary antibody is conjugated with a label and binds to Primary antibody

39
Q

What does SDS PAGE do and how does it work?

A

Proteins are separated by molecular weight. Detergent is used to break the tertiary structure and gives them a charge relative to their molecular weight. Smaller molecules will run further than larger ones

40
Q

What does Isoelectric Focusing do?

A

Proteins are separated based on their isoelectric points.

Stable pH gradient is established in gel and proteins will migrate until it reaches a pH that matches its pI

41
Q

What does 2D-PAGE do?

A

Seperates proteins by isoelectric point in one direction and by molecular weight in the other

42
Q

What is an Enzyme Assay used for? How is it done?

A

Used to measure the activity of an enzyme.
Performed at optimal pH, temperature and ionic strength, the production of product or disappearance of substrate is constantly monitored

43
Q

What are the two main markers for Liver damage?

A

Aspartate Transaminase

Alanine Transaminase

44
Q

What are the three main markers for an MI?

A

Creatine Kinase
Lactate Dehydrogenase
Cardiac Troponin

45
Q

What is the main marker for Pancreatitis?

A

Amylase

46
Q

How does Enzyme-Linked Immunoabsorbent Assay (ELISA) work? Whats it used for?

A

Primary antibody (specific to protein) is immobilised on solid surface.
Solution to be assayed is applied to antibody coated wall.
Secondary antibody conjugated with an enzyme binds to the antigen-antibody complex. Substrate is then added and converted by enzyme into coloured product.
Binding of secondary antigen is proportional to concentration of protein.
Used to determine concentration of a protein

47
Q

How does Reverse transcriptase - PCR work?

A

RNA template is converted into cDNA using a reverse transcriptase and the mRNA strand is digested and the cDNA is used as a template strand for PCR to take place

48
Q

What is Karyotyping?

A

Cells are arrested during cell division and chromosomes are stained. Chromosomes are ordered by length under microscope

49
Q

How does Fluorescence in Situ Hybridisation work?

A

Probe DNA is labelled with fluorescent dye, DNA is denatured and allowed to hybridise. Shows whether specific DNA is present and where its located

50
Q

What are the two types of Chromatin?

A

Euchromatin - Lightly packed chromatin under transcription

Heterochromatin - Tightly packed chromatin, genes not expressed

51
Q

What is Polyploidy? What commonly causes it?

A

When an embryo gains an extra set of chromosomes (a haploid set of chromosomes)
Commonly caused by polyspermy

52
Q

What is Aneuploidy? How does it occur?

A

Abnormal number of chromosomes that is not a multiple of the haploid number
Occurs because of the failure of a chromosome to separate properly
Monosomy is the loss of a chromosome
Trisomy is the gain of a chromosome

Medicine (10 decks)

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