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Semester 1 Missed Lectures > MCBG > Flashcards

MCBG Flashcards

1
Q

What is the function of cytoplasmic extensions?

A

Communication between cells.
Movement.
Increase surface area for more phagocytosis to occur.

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2
Q

What are the functions of lysosomes?

A

To bind to a vesicle and break the contents down, by releasing hydrolytic enzymes.

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3
Q

What is the denser portion of the Golgi, and what is its function?

A

The cis end.
It receives vesicles from the RER.

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4
Q

What are the two key properties of proteins?

A

Their size - number of amino acids joined together.
Their isoelectric point - the point at which the protein has no overall nett charge.

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5
Q

Outline some characteristics of alpha-helices.

A

They are tightly coiled chains with side chains.
It is a right-handed helix.
Hydrogen bonds stabilise between the amine and carbonyl groups.

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6
Q

Outline some characteristics of beta-pleated sheets.

A

They have extended confirmations.
They are composed of adjacent beta-pleated strands.
They are arranged in an anti-parallel direction for stability.
Hydrogen bonds stabilise them, formed between the amine group and the carbonyl group.

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7
Q

How does protein folding occur?

A

Through localised folding with the stable conformations maintained.
It is driven to find the most stable conformation.

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8
Q

What are amyloid fibres?

A

They are misfolded, insoluble beta-pleated sheet aggregations.
They are stabilised by hydrophobic interactions between amino acid residues.
They can cause disease.

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9
Q

What are clefts and crevices of enzymes?

A

Clefts are spaces between subunits.
Crevices are formed by specific folding of the protein to exclude water.

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10
Q

What can Km be used to determine?

A

Whether more substrate or enzyme is required to increase the rate of reaction.

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11
Q

What is V0?

A

The initial rate of reaction.

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12
Q

What is 1 unit?

A

The amount of enzyme that produces 1micromole of product per min under standard conditions.

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13
Q

What are the different types of bonds involved in DNA?

A

Phosphodiester bonds between phosphate group and sugar backbone - they are covalent bonds.
Hydrogens bonds are between bases.
Van-der waal forces also stabilise the DNA helix.

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14
Q

What is Crick’s central dogma?

A

Genes, encoded for by DNA are transcribed into mRNA. The mRNA is then translated into an amino acid sequence, which forms a protein.

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15
Q

What are the specific regions needed for sex determination?

A

Pseudoautosomal regions and genes, which are specific to X and Y chromosomes.

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16
Q

Which type of chromatin can be transcribed?

A

Eurchromatin, as the DNA is loosely compacted in the nucleosome form.

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17
Q

What are the types of purine and pyrimidine bases?

A

Purine = adenosine and guanine.
Pyrimidine = thymine, cytosine and uracil (replaces thymine in RNA).

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18
Q

What are the groups attached to the 5’ and 3’ ends?

A

5’ = phosphate group, which is negatively charged.
3’ = hydroxyl group.

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19
Q

What C number is the phosphate group attached to, and what C number binds to the adjacent nucleotide?

A

Phosphate = C5.
C3 binds to the adjacent nucleotide’s phosphate group.

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20
Q

Are G-C or A-T/U base pairs stronger?

A

G-C are stronger as they contain 3 hydrogen bonds, whereas A-T/U only contain 2 hydrogen bonds.

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21
Q

What is Down’s syndrome caused by, the abnormality and some clinical features?

A

It is caused by non-disjunction of chromosome 21 during meiosis.
It leads to trisomy of chromosome 21.
Patients often have delayed growth, mild intellectual disabilities, and characteristic facial features.

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22
Q

What are telomeres and what are their function?

A

They are repeat sequences at the end of the chromosome.
They protect the chromosome whilst replicating.

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23
Q

What happens to the length of telomeres as the cell proliferates?

A

They shorten.

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24
Q

What are the 7 groups of chromosomes based off, and what are X and Y chromosomes placed in?

A

They are based on size and position of the centromere.
X is in group C and Y is in group G.

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25
Q

What is G0?

A

A phase of the cell cycle where nothing is happening - a resting or quiescent phase.
This often occurs when there is genetic damage and so it is sent in G0 to repair or trigger apoptosis.

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26
Q

What types of cells does meiosis occur in?

A

Germline cells.

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27
Q

What are diploid and what are haploid cells?

A

Diploid cells have 2 copies of each chromosome - 46 chromosomes in the cell.
Haploid cells have 1 copy of each chromosome - 23 chromosomes in the cell.

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28
Q

What is the point at which the chromosomes cross over during prophase I called?

A

Chiasmata.

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29
Q

Explain how recombination occurs.

A

Homologous chromosomes pair up.
Crossing over at chiasmata of chromatids occurs.
The homologous chromosomes then separate with a different genetic complement.

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30
Q

Why does meiosis occur?

A

To maintain a constant number of chromosomes.
For genetic variation and diversity.

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31
Q

How long do spermatogenesis and oogenesis take, respectively?

A

Spermatogenesis = 60 days.
Oogenesis = 12-50 years.

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32
Q

What is ataxia tangliectasia?

A

It is an autosomal recessive, neurodegenerative disease, where damage to the cerebellum leads to difficulty moving and with co-ordination.
There is a mutation in the ATM gene.
They have a weakened immune system and an increased sensitivity to radiation.
The homology directed repair is disrupted, increasing the risk of cancer.

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33
Q

What is the process of DNA damage response?

A

Signals sent out by damaged DNA.
Sensors receive the signals.
Traduces activate effectors.

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34
Q

What are the different effectors for DNA damage response?

A

Stimulation of apoptosis of the cell.
DNA repair mechanisms for the cell.
Transcription to remove the mutation.
Cell enters senescence so cannot be replicated.

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35
Q

What are the 3 main cell cycle checkpoints?

A

G1/S - the cell is checked to ensure it has the correct conditions and proteins, and for DNA damage, before the DNA is replicated.
G2/M - the cell is checked to ensure the DNA was correctly replicated, before the cell divides.
Metaphase (spindle) checkpoint - checks to ensure the spindle fibres are correctly bound to the centromeres so that non-disjunction does not occur.

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36
Q

What requires base-excision repair, and how does it occur?

A

When cytosine is deaminated to uracil.
The base is removed by endonuclease, and then that section of backbone is removed.
DNA polymerase adds the correct base and DNA lipase stitches it together.

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37
Q

What requires nucleotide-excision repair, and how does it occur?

A

Dimerisation of thymine.
The dimmer and the surrounding nucleotides are removed by endonuclease.
DNA polymerase adds the correct nucleotides and DNA ligase stitches it back together.

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38
Q

What requires mismatch repair, and how does it occur?

A

This is where the incorrect base is incorporated into the sequence and is removed by endonuclease, with adjacent bases.
DNA polymerase incorporates the correct nucleotides into the sequence, and DNA ligase stitches it together again.

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39
Q

What is non-homologous end joining?

A

A double stranded DNA break occurs.
Exonucleases resect the excess base pairs around the break.
DNA ligase stitches the two strands back together.
The new DNA is not an exact copy.

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40
Q

What is homology-directed repair?

A

When there is a double-stranded DNA break, the other copy of the gene in the genome can be used.
Exonuclease resects the excess nucleotides each side of the break.
The unaffected copy is used as a template.
A heteroduplex is formed and one side of the DNA molecule is copied by DNA polymerase.
This strand is then duplicated to form the complementary strand and DNA ligase stitches them together.

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41
Q

What is lynch syndrome, and what is it caused by?

A

It is an autosomal dominant condition that increases the risk of colorectal cancer.
It is caused by mutation in mismatch repair genes.

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42
Q

What is a phenotype?

A

An observable characteristic due to interaction between the genotype and the environment.

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43
Q

What is a homozygous, heterozygous and hemizygous?

A

Homozygous = two alleles of the same gene.
Heterozygous = two different alleles of the same gene.
Hemizygous = only one allele of a gene.

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44
Q

What can autosomal recessive diseases do that autosomal dominant diseases cannot?

A

They can skip generations.

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45
Q

What mode of inheritance is fragile X syndrome, and who is affected more?

A

X-link dominant.
Females are affected more as they only require one of the mother or father to be affected to be affected themselves - they have 2 X alleles and so are twice as likely as males.

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46
Q

What is polygenic inheritance?

A

Where multiple genes are required to influence the phenotype.
If there is enough genes involved in the phenotype then it becomes continuous, such as skin pigmentation.

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47
Q

What is albinism’s mode of inheritance?

A

A polygenic trait, that is inherited in a recessive manner, controlled by the A gene.
They require one of the two alleles to be homozygous recessive.

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48
Q

What influences psychiatric disorders?

A

Multiple genes and the environment.

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49
Q

Where does linkage occur, and what does it increase the the chance of?

A

Linkage occurs on the same chromosome. On different chromosomes, they’re not linked. The closer genes are to each other, the increased likelihood that they will be linked.
It increases the chance that alleles are inherited together.

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50
Q

What is linkage disequilibrium?

A

Where loci on different chromosomes are inherited together.

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51
Q

What is penetrance?

A

The description of whether there is clinical expression of a phenotype in a person.
It is the percentage of people with a genotype that show symptoms.

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52
Q

What is expressivity, and what is it affected by?

A

The different clinical presentation between people with the same genotype - how severe it is.
It is affected by the environment.

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53
Q

What is diamond-blackfan anaemia?

A

A low red blood cell count due to decreased erythroid progenitor cell in the bone marrow.
This is because of mutations in ribosomal genes.

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54
Q

What are some symptoms of diamond-blackfan anaemia?

A

Cleft palate.
Upper limb abnormalities.
Cardiac defects.
Urogenital malformations.

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55
Q

What are the 3 different types of RNA?

A

mRNA - messenger RNA is the transition molecules between DNA and protein.
rRNA - ribosomal RNA is used for protein translation.
tRNA - transfer RNA reads the triplet code to synthesise a protein.

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56
Q

How many kinds and copies are there of each type of RNA?

A

rRNA - few different kinds with many copies of each. It is the most abundant RNA.
mRNA - hundreds of thousands of different kind with only a few copies. It is the least abundant.
tRNA - around 100 kinds with many copies of each. It is the second most abundant.

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57
Q

What permits the RNA polymerase to bind, and what can control the level of gene expression?

A

A promoter - a sequence of nucleotides.
Enhancers - upstream sequences.

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58
Q

What direction is DNA read and transcribed in by RNA polymerase?

A

It is read in a 3’ to 5’ direction.
It is synthesised in a 5’ to 3’ direction.

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59
Q

What do introns do?

A

They have regulatory roles, but do not code for proteins and so are spliced out.

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60
Q

How does polyadenylation occur?

A

RNA polymerase is cleaved off by specific endonuclease and polyA polymerase synthesises the A tail - a sequence of A nucleotides.

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61
Q

What does transcription depend on, and what occurs if this is altered?

A

It depends on the reading frame.
If this is altered, the incorrect mRNA sequence, thus polypeptide sequence will be synthesised.

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62
Q

What is translation carried out by?

A

Polysome - a string of ribosomes that bind to mRNA and translate it simultaneously.

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63
Q

How do tRNA molecules work?

A

One side of the tRNA molecule recognises the base pair code and the other picks up the amino acid to link it to the polypeptide.
They can move to facilitate this.

64
Q

How are amino acids charged before given to the ribosome?

A

They are activated by the tRNA, when it binds to it, forming an aminoacyl-tRNA complex.
This is catalysed by the aminoacyl-tRNA synthetase.

65
Q

What is the anticodon?

A

It is a reverse-complementary stretch of nucleotides that bind to the unique amino acid.

66
Q

What is a wobble position?

A

It is where the 3rd base of the anticodon binds more weakly to the codon and so the tRNA can recognise more than one codon - multiple codons can be used for one amino acid.

67
Q

How does initiation of translation occur?

A

The methionyl-tRNA recognises the AUG.

68
Q

How does elongation of translation occur?

A

The next amino acid is placed into the A-site of the ribosome.
The ribosome then transfers the polypeptide from the P-site to the A-site and forms a peptide bond in the A-site, adding the sequential amino acid to the polypeptide chain.
The ribosome then translocates, placing the polypeptide in the P-site, freeing the A-site again.

69
Q

How does termination of translation occur?

A

The stop codon is recognised and the polypeptide is released through the ribosome E-site.

70
Q

What are some exogenous sources of mutations?

A

Ionising radiation.
Chemicals.
Anti-cancer agents.

71
Q

What are some endogenous sources of mutations?

A

DNA replication defects.
Transposable elements - small DNA elements that can move about the genome.
Free radicals.

72
Q

Why else can mutations occur, and what is required for all mutagens to be translated into a mutation?

A

They can be spontaneous.
There must be a defective or error-prone DNA repair mechanism.

73
Q

What affects can mutations have?

A

They can be deleterious - a loss of function or a gain of an unwanted function.
They can be adaptive - they increase the ability of a person to survive.
They can have no function.

74
Q

What are deamination mutations?

A

Where an amine group is removed from cytosine to form uracil.
This can lead to two separate strands of DNA being produced.

75
Q

What is dimerisation?

A

The formation of a dimer between two similar base pairs.

76
Q

What are some small scale/ micro mutations?

A

Insertion - the addition of a base pair.
Deletion - the removal of a base pair.
Inversion - swapping two base pairs.
Duplication - replication of one or more base pairs.

77
Q

What are synonymous mutations? Why is the outcome so?

A

They are mutations that have no effect.
This is because the mutation swaps a base pair for the same base pair and so the protein will be unchanged.

78
Q

What are missense mutations?

A

They are base substitutions which lead to the incorrect amino acid being involved in the sequence.

79
Q

What are nonsense mutations?

A

Where a premature stop codon is added due to a base substitution, leading to a truncated protein.

80
Q

What are frameshift mutations and what is the effect?

A

There is an addition or deletion of a base, which changes the reading frame.
This means that all of the subsequent amino acids are no longer coded for and so the protein structure and function will change.

81
Q

What can occur if there has been 3 base pairs inserted or deleted?

A

As the reading frame has not changed, there may be no effect on the protein synthesised.

82
Q

What is an SNP?

A

Single nucleotide polymorphism - a change in a single base pair.

83
Q

What are anonymous SNPs, non-coding SNPs, and coding SNPs?

A

Anonymous = no known effect of the single base pair change.
Non-coding = a change in a base pair outside of a gene.
Coding = a base pair change inside a gene.

84
Q

What can the effects of SNPs be?

A

They may be synonymous/ silent.
They may cause missense mutations (different amino acid).
They may cause nonsense mutations (truncated protein).
They may change the gene expression (if a non-coding SNP).

85
Q

What are transition and transversion DNA substitutions?

A

Transition = changing a base to the same type (pyrimadine to pyrimadine/ purine to purine).
Transversion = changing a base to a different type (pyrimadine to purine or vice versa).

86
Q

What is sickle cell anaemia?

A

It is a missense base substitution, where amino acid 6 is changed from glutamate to valine, due to a mutation in codon 7 of the HbB gene.

87
Q

What is alpha-Wayne sickle cell anaemia due to?

A

A base pair deletion.

88
Q

What is alpha-CS sickle cell anaemia due to?

A

A base pair insertion.

89
Q

What are the different types of large scale/ chromosomal mutations?

A

Deletion - 1 chromosome.
Insertion - 2 chromosomes.
Duplication - 1 chromosome.
Inversion - 1 chromosome.
Translocation - 2 chromosomes.

90
Q

What is a chromosomal deletion, duplication, and inversion?

A

Deletion - the removal of a part of a chromosome.
Duplication - one arm of a chromosome is copied and reinserted into the chromosome, leading to copies of genes.
Inversion - some of the genes of a chromosome are switched round.

91
Q

What are insertion and translocation chromosomal mutations?

A

Insertion - the deletion of one section of a chromosome and adding it to another.
Translocation - the swapping of genetic information between two different chromosomes.

92
Q

What is Cri du Chat syndrome? What does it lead to?

A

Deletion of the short (p) arm of chromosome 5.
They have low birth weight, growth retardation, microcephaly and cardiac defects.

93
Q

What are Robertsonian translocations? What can the effect be?

A

Where acrocentric chromosomes are split at the centromere.
The q arms of the two chromosomes fuse and the p arms are lost.
It leads to the loss of a chromosome - it can have no effect or lead to Down/ Patau syndrome.

94
Q

What is polyploidy?

A

The gain of a haploid set of chromosomes.
Due to 2 sperm fertilising 1 egg.

95
Q

What is aneuploidy?

A

The loss or gain of a single chromosome due to non-disjunction.

96
Q

What is the defects of Down, Patau, and Edwards syndromes?

A

Down syndrome = trisomy of chromosome 21.
Patau syndrome = trisomy of chromosome 13.
Edwards syndrome = trisomy of chromosome 18.

97
Q

What are the symptoms of Patau syndrome?

A

Microcephaly.
Cleft palate.
Polydactyly.
Intellectual disabilities.

98
Q

What is the defect of Kleinfelter and Turner syndromes?

A

Kleinfelter syndrome = extra X chromosome: 47,XXY.
Turner syndrome = loss of X chromosome: 45,X.

99
Q

What is mosaicism?

A

Non-disjunction in early mitosis.
It is the presence of two or more cell lines in some of the body, not all.

100
Q

What is cytogenetic testing and what are cytogenetic testing methods?

A

It is identifying changes in chromosomal number.

Cytogenetic analysis - karyotyping.
Fluorescent in situ hybridisation.
DNA sequencing.
Microarray hybridisation.

101
Q

Benefits of undergoing cytogenetic testing?

A

To ensure diagnosis and prognosis of clinical problems.
For better clinical management and treatment.
To assess future reproductive risks.

102
Q

Why would somebody be sent for cytogenetic testing?

A

Infertility.
Recurrent foetal loss.
Birth defects.
Abnormal sexual development.
Leukaemia.

103
Q

Where can mutations occur, and what are balanced and unbalanced mutations?

A

They can occur in the somatic cells or germ line.
They can be balanced where no genetic information is lost and there is no phenotypic change.
They can be unbalanced, where genetic information is lost.

104
Q

What is the haem group bound to the polypeptide chain by?

A

Histidine residue.

105
Q

What is the benefit of haemoglobin’s affinities for oxygen in different partial pressures?

A

At a high partial pressure in the lungs, there is a high affinity for oxygen, meaning that there is more oxygen taken up.
At a low partial pressure in the tissues, there is a lower affinity for oxygen, meaning that it will give up the oxygen more freely.
This means that there is a large percentage of oxygen dissociation, so the tissues are supplied with more oxygen

106
Q

How does proteolytic activation occur?

A

Through the breaking of a peptide bond. It is an irreversible process.

107
Q

What controls proteolytic activation of pancreatic proteases?

A

Trypsin.

108
Q

What is the modular structure of prothrombin?

A

At the C-terminal, there is a serine protease which activates fibrinogen once cleaved off.
It has a Gla domain that helps target it to the site of action.
It contains 2 Kringle domains that help keep prothrombin in its inactive form.

109
Q

What is the structure of fibrinogen?

A

It is a precursor molecule that is composed of 3 polypeptide chains, that for a triple-helical alpha helix.
There are 2 globular heads.
There are fibrinopeptides that prevent fibrinogen molecules coming together.

110
Q

How is fibrinogen converted to fibrin?

A

The fibrinopeptides are cleaved off by thrombin.
Fibrin monomers can then form H-bonds between each other, forming a soft clot.
Cross-linking between lysine and glutamine residues, catalysed by transglutaminase occurs.

111
Q

What sustains the activation of the clotting cascade?

A

Thrombin - positive feedback.

112
Q

What does the Gla domain do?

A

It is negatively charged and is attracted to the positively charged Ca2+ ions released at the site of damage.
It, there, brings together clotting factors.

113
Q

How is the clotting cascade inhibited?

A

Dilution of clotting factors.
Removal of clotting factors by the liver.
Digestion of proteases.
Binding of specific inhibitors.

114
Q

Where are proteins for the cytosol and protein for the membrane or secretory pathway made?

A

Cytosolic proteins are synthesised by free ribosomes.
Membrane/ secretory proteins are synthesised in the RER.

115
Q

What are the two types of protein secretion?

A

Constitutive - continuous secretion.
Regulated - controlled secretion, seen in endocrine, exocrine and neurocrine secretion.

116
Q

What are the functions of the endoplasmic reticulum for protein synthesis?

A

Insertion of proteins into membranes.
Proteolytic cleavage - signal peptidase cleaves the signal peptide.
Glycosylation - adding sugars using enzymes.
Formation of disulphide bonds.
Folding of proteins.
Hydroxylation of lysine and proline residues.

117
Q

What is the function of the Golgi in protein synthesis?

A

Receiving proteins through the Cis- side.
Further protein modifications.
Release of proteins through the Trans- side.

118
Q

What enzyme glycosylates proline and lysine residues?

A

Prolyl hydroxylase.

119
Q

Which enzyme forms covalent bonds between lysine residues?

A

Lysyl oxidase.

120
Q

How can we analyse DNA at a nucleotide level?

A

DNA sequencing.
PCR and restriction analysis.

121
Q

How can we analyse DNA at the gene level?

A

RT-PCR.
DNA fingerprinting/ profiling.
Microarray.

122
Q

How can we analyse proteins?

A

Protein electrophoresis.
Immunoassays.
Enzyme assays.

123
Q

What are restriction enzymes?

A

They are specific endonucleases (restriction enzymes) produced by bacteria to cut specific DNA sequences (restriction sites).
These restriction sites are often palindromes.

124
Q

What are palindromes?

A

They are sequences of DNA that can be read the same both ways.

125
Q

What are sticky ends?

A

They are cuts through DNA strands on different strands that are not cut straight down - they overlap each other.
They can be stitched back together by DNA ligase.
They are cut by specific endonucleases.

126
Q

What is DNA electrophoresis?

A

It is the technique used to separate DNA fragments based on their size.

127
Q

What are the requirements for gel electrophoresis?

A

A gel to hold the DNA fragments in.
A buffer to apply the charge to the DNA fragments.
A power supply to generate the charge difference across the gel.
A staining/ detection method.

128
Q

Why will DNA fragments move and what will their movement speed be based off of?

A

They migrate towards the anode (+ve charge) as DNA is negatively charged.
They are differentiated by their size - smaller fragments can move through the gel faster.

129
Q

Why is restriction analysis used?

A

To investigate sizes of DNA fragments.
To see for any mutations.
To investigate DNA variation.
DNA cloning.

130
Q

What are plasmids?

A

They are small, circular dsDNA found in bacteria.
They often code for antibiotic resistance and can be transferred between bacteria.
They carry genes that can be replicated.

131
Q

How does gene cloning occur?

A

The required DNA fragment is identified and cut using specific endonucleases.
The DNA fragment is inserted into the plasmid.
The plasmid is reinserted back into the host - a bacterium.
The DNA is replicated in the bacterium, it is then identified and isolated.

132
Q

Why clone human genes?

A

To make useful proteins.
To understand what genes do.
For genetic screening.
For genetic therapy - replacing defective genes with a normal copy.

133
Q

Outline the process of PCR.

A

A sample of DNA is heated to 95 degrees to separate the two DNA strands.
The sample is then cooled to around 55 degree to allow the specific primers synthesised by primase to anneal to the DNA.
The temperature is then increased the 72 degrees to allow TAQ-polymerase to copy the DNA fragment between the two primers.
The reaction is repeated many times.

134
Q

What is the aim of PCR?

A

To amplify a specific DNA sequence.
To check for single base mutations.
To investigate small deletions or insertions.
To investigate variation and genetic relationships.

135
Q

What is quantitative PCR?

A

It is where the dNTPs used during PCR are fluorescently labelled to allow the expression of different genes to be seen.

136
Q

Why are molecular techniques used?

A

To investigate single base pair mutations.
To investigate small deletions or insertions.
To investigate variation and genetic relationships.
To amplify specific DNA fragments.

137
Q

Why is DNA sequencing done?

A

To see if there are mutations.
To confirm the identity of DNA fragments.
To analyse the fine structure of a gene.

138
Q

How can DNA sequencing be performed?

A

PCR is used to amplify lots of DNA fragments.
Fluoresecently-labelled bases are used as the substrate to allow them to be incorporated into the sequence.
The bases do not allow for any additional bases to be added (di-dNTPs).
Different DNA fragment lengths are generated and sequenced using gel electrophoresis to produce a DNA sequence.

139
Q

What does protein electrophoresis do? Give an example of what it can be used for.

A

It separates proteins based on their size, charge and shape.
It can be used to recognise certain antibodies.

140
Q

What are the requirements for protein electrophoresis?

A

A gel to hold the proteins in, allowing the separation.
A buffer to apply the charge to the proteins.
A power supply to generate the charge difference across the gel.
A staining/ detection method.

141
Q

What is the process of SDS-PAGE?

A

Proteins are separated by SDS.
They are then run through protein electrophoresis.
They are separated based on their mass, using mass spectrometry.

142
Q

What are polyclonal and monoclonal antibodies?

A

Polyclonal = multiple antibodies produced by multiple B-lymphocytes that bind to 1 antigen on one epitope.

Monoclonal = 1 antibody produced by 1 B-lymphocyte that binds to 1 antigen on 1 epitope.

143
Q

What are immunofluorescent assays?

A

Antigens are bound to a well.
A primary antibody binds to the antigen and the sample is washed for any excess antibody.
A secondary antibody binds to the primary antibody and the sample is washed to remove any excess antibody.
The secondary antibody has a fluorescent tag attached which can be visualised.

144
Q

What is western blotting?

A

It is used to measure the presence of a protein in a tissue:
- The protein is denatured and run through electrophoresis.
- Primary antibodies are added, which bind to specific proteins.
- Secondary antibodies bind to the primary antibodies.
- The signal attached to the secondary antibody can then be seen.

145
Q

What does ELISA stand for and why is it used?

A

Enzyme-linked immunosorbent assay.
It is used to see the presence and concentration of a protein in a solution.
The rate at which is coloured product is formed is proportional to the amount of antigen present.

146
Q

How does ELISA work?

A

An antigen coated well has primary antibodies added to the solution in excess.
Once the antibodies have bound, the solution is washed to remove excess antibody.
Then, enzyme-linked secondary antibodies are added, allowing to bind and then washed to remove any excess.
A substrate for the enzyme is added and a coloured product is produced.

147
Q

What are enzyme assays used to measure?

A

They are used to measure the rate of a chemical reaction in different samples.

148
Q

What are some continuous and discontinuous assays?

A

Continuous = spectrophotometry (and chemoluminescence).
Discontinuous = chromatography and radioactivity.

149
Q

What are enzyme assays used for?

A

Identification of metabolic disorders in tissues.
Diagnosis of disease - specific enzymes released.

150
Q

What are some enzymes released from liver damage, pancreatitis, liver damage due to alcohol, and bone disorders?

A

Liver damage = ALT and AST.
Pancreatitis = pancreatic amylase/ lipase.
Liver damage due to alcohol = G-glutamyltransferase.
Bone disorders = alkaline phosphate.

151
Q

How are MIs tested for?

A

Troponin I and T test, using ELISA.

152
Q

What is DNA hybridisation?

A

Denaturing DNA, adding a radioactive label and then renaturing the DNA, allowing it to be seen.

153
Q

What is a DNA probe and what are some are characteristics of DNA probes?

A

They are DNA sequences.
They can have partial of the target sequence.
They do not affect the position of the DNA sequence.

154
Q

How is Southern blotting performed?

A

DNA is broken into fragments by specific endonucleases and run through an agarose gel.
The DNA fragments are transferred onto a sheet and labelled with a DNA probe.
The probe finds complementary sequences and fluoresces them.

155
Q

Why use Southern blotting?

A

To investigate gene structure.
To investigate for mutations.
To investigate for genetic relationships and variation.

156
Q

What are microarrays?

A

Where thousands of genes are tested simultaneously, of a normal and a different cell, usually a cancer cell.
It allows gene expression to be analysed.

157
Q

What is FISH?

A

Fluorescent in situ hybridisation is where DNA is denatured and labelled with a fluorescent DNA probe to identify particular sequences in chromosomes.

Semester 1 Missed Lectures (3 decks)

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