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Semester 3 > MCBHD > Flashcards

MCBHD Flashcards

1
Q

what chromosomal abnormality is the most common

A

aneuploidies

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2
Q

daughter cells of meiosis and mitosis

A

identical - mitosis

different in meiosis

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3
Q

what is karyotyping good for

A

big deletions/duplications
missing/duplications chromosomes

no need to know what you are looking for

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4
Q

what is FISH good for

A

micro deletions/microduplications
looking for aneuploidies

but you need to know what you are looking for

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5
Q

quantitive PCR

A

only picks up aneuplodies

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6
Q

array-CGH

A

no need to know what you are looking for

good for deletions/duplications

most of genome (many probes)
but produces a lot of data

not good at detecting mosaicism/detecting balanced rearrangements/where the aberration is

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7
Q

aneuploidy vs polypoidy

A

aneuploidy = more than 2 copies of a chromosome

polypoidy = more than 2 sets of chromosomes

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8
Q

2 ways that can result in aneuploidy

A

non-disjunction–> daughter cells having incorrect number

mosaicism

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9
Q

3 common tirosomies and features

A

21 - downs
-epicanthic folds/almond eyes/flat nasal bridge/single palmar crease/sandal gap/short/hypotonia/cardiac problems

18 - edwards
-exomphalos/overlapping fingers/rocker bottom feet/heart and kidney defects

13 - patau
-midline cleft palate/scalp defects/exomphalos/polydactyl/hypotelorism close eyes/brain defects

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10
Q

sex chromosome aneuploides

A

45X0 = turners

47XXY = klinefelter

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11
Q

translocation types

A

reciprocal / robertsonian (2xp or 2xq)

robertsians therefore are between acrocentric chromosomes

balanced/unbalanced(missing/extra material)

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12
Q

inversion types

A

paracentric - not including centromere

pericentric - including centromere

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13
Q

ring chromosome

A

ends of abnormal chromosome fuse

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14
Q

what kind of inheritance pattern is cystic fibrosis

A

autosomal recessive

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15
Q

2 non – Mendelian Inheritance

A

mitochondrial (homo/heteroplasmy)

multi-factorial

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16
Q

what is the tandem repeat at the end of chromosomes

A

TTAGGG

17
Q

5 main histone types

A 
H1
H2A
H2B
H3
H4
18
Q

do histones have introns

A

no

19
Q

histone N and C terminal ends

A

N - highly basic

C - highly hydrophobic

20
Q

3 different levels of genes can be transcribed to

A

Gene 1 = genes that are highly expressed “housekeeping genes”

Gene 2 = less expressed

Gene 3 = only expressed in certain tissues
These genes also can be affected by a stimulus to start their transcription/expression

21
Q

By what mechanism does each cell in our body achieve differential gene expression

A

2 main ways:

  • Regulatory transcription factors
  • Chromatin remodeling
22
Q

3 types of RNA polymerase

A 
I = rRNA
II = mRNA
III = tRNA
23
Q

Oestrogen responsive genes - how it brings RNA polymerase II

+ what interferes with this

A
  1. oestrogen binds to oestrogen free receptor
  2. they bind to TATA box
  3. recruitment of general transcription factor to bind to the Tata box
  4. recrutiment of RNA polymerase

Tamoxifen interferes by preventing TF from binding–> used to prevent tumours from growing

24
Q

role of acetylation of histones (chromosome remodelling)

A

histones = +vely charged (DNA = -vely)

TF recruit Histone acetylase

it neutralises the positive charge at N-terminal of histone –> no longer bind to DNA molecule

opens up the chromosome

Allows access to general TF and RNA polymerase for transcription

25
Q

what are Restriction Enzymes

what 2 things do they do

A

bacteriophages (viruses that infect bacteria)

These can be purified and used to digest DNA

There are multiple restriction enzymes but only type II restriction enzymes are useful, because they are sequence specific.

  1. recognise specific DNA sequence
  2. break phosphodiester bonds
26
Q

Components of a PCR Reaction

A

Template – DNA to amplify

Primers – Short pieces of ssDNA (15-30bp)

Polymerase – thermostable enzyme (to about 95degrees)

Nucleotides – single base mixture (dNTPs)

Buffer – To maintain pH

MgCl2 – Essential for polymerase activity

27
Q

PCR temperature steps

A

94-denature

60 - primer anneal

72 - extension

28
Q

equation to work out how many copies of target DNA we get with PCR

A

n=cycle number

no. of copies = 2^ n-1

29
Q

what happens to pre-mRNA after transcription

A
  1. methylation of 5’ cap to help ribosome know where to translate from
  2. poly A 3’ (adding AAUAAA-U/G —> AAUAAA-AAAA) stabilising
  3. splicing
    (alternative splicing=> isomers)
  4. TREX binds to the exon junction complexes to export mRNA to the cytoplasm for translation
30
Q

which type of chromatin is stained darker with giemsa stain

A

Heterochromatin - AT rich and it is tightly packed because here the genes are inactive (i.e. not being transcribed).

Semester 3 (6 decks)

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