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Physiology 2 > gene structure and chromosomal abnormalities > Flashcards

gene structure and chromosomal abnormalities Flashcards

1
Q

what makes up the human genome?

A

Genes - exons and introns
intergenic regions
small DNA molecule in mitochondria

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2
Q

how many bases in whole human genome?

A

3.2billion

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3
Q

what is a gene

A

the basic physical and functional unit of heredity

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4
Q

how many genes in human genome

A

20,000-23,000

makes up 2% of genome

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5
Q

introns

A

AKA intragenic regions

non-coding regions found within genes

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6
Q

intergenic regions

A

do not contain protein-coding sequences - between the genes

contain regulatory elements involved in switching genes on and off

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7
Q

mitochondrial DNA

A

circular double-stranded DNA molecule
codes for 37 genes
inherited exclusively from oocyte - maternal pattern of inheritance

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8
Q

what makes up chromatin?

A

DNA
RNA
protein

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9
Q

what is the main protein in chromatin?

A

histones

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10
Q

formation of chromatin

A

DNA wound around histones to form nucleosomes which are organised into solenoids.
Solenoids loop up into structure of chromatin

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11
Q

types of chromatin?

A

euchromatin

heterochromatin

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12
Q

euchromatin

A

open chromatin and prevalent in parts of genome being regularly used - where genes are switched on

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13
Q

heterochromatin

A

condensed for of chromatin made up of tight loops - most abundant in parts of the genome where genes are switched off

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14
Q

what do the light and dark stained parts represent on chromosomes?

A 
light = open chromosome structure, euchromatin
dark = condensed chromosome, heterochromatin
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15
Q

what is the p arm?

A

short arm structure of chromosome

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16
Q

what is the q arm?

A

long arm of chromosome

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17
Q

where is centromere located?

A

constricted point of chromosome, closer to top of chromosome

18
Q

how many DNA molecules are there in a chromosome?

A

1

19
Q

what introduces variation during meiosis?

A

crossing over
independent assortment
errors/ mutations in replication

20
Q

DNA damage in germline cells

A

changes cause heritable defects

21
Q

DNA damage in somatic cells

A

changes cause non-heritable local changes

22
Q

when does crossing over occur?

A

1st meiotic division

23
Q

mutations

A

drive evolution but can be pathogenic, causing disease

24
Q

when does crossing over occur?

A

1st meiotic division - prophase 1

25
Q

when does independent assortment occur?

A

before crossing over in first meiotic division

26
Q

what happens in crossing over

A

homologous chromosomes exchange genetic material at chiasma

introduces genetic variation

27
Q

which enzyme corrects mistakes by RNA polymerase?

A

MMR excision

28
Q

what is MMR excision

A

goes along newly made strand and looks for mistakes in base pairing by RNA polymerase - wrong bases and corrects them
mismatch repair

29
Q

what happens independent assortment?

A

during anaphase 1
centromeres do not duplicate and divide so only one member of each pair of chromosomes migrate to each daughter cell - either maternal or paternal
mix of chromosomes is different from cell to cell

30
Q

what is loss or gain of a chromosome called?

A

aneuploidy

31
Q

what is loss of a single chromosome

A

monosomy

32
Q

gain of one homologous chromosome

A

trisomy

33
Q

gain of 2 homologous chromosomes

A

tetrasomy

34
Q

what is addition of one or more complete haploid components

A

polyploidy

35
Q

turner syndrome

A

monosomy X

36
Q

nullisomic gametes

A

missing chromosomes

result in monosomic zygote

37
Q

disomic gametes

A

double no. chromosomes

results in trisomic zygote

38
Q

banding

A

looking at band pattern of homologous chromosomes to see if they are the same

39
Q

what is the most common trisomy?

A

16

40
Q

symptoms of downs syndrome

A

learning disorder
issues with social skills
shorter
heart defects

Physiology 2 (20 decks)

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