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PRINCIPLES OF FUN > Chromosomes, Cell Division, Meiosis and Chromosome Abnormalities > Flashcards

Chromosomes, Cell Division, Meiosis and Chromosome Abnormalities Flashcards

1
Q

what is the structure of a eukaryotic chromosome?

A

Linear
telomeres at the edges
centromere in the middle

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2
Q

where are the regions of euchromatin and heterochromatin in a eukaryotic chromosome?

A

heterochromatin in the middle

euchromatin at the edges (however telomeres are composed of euchromatin)

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3
Q

what are the different phases in mitosis?

A

G1
S
G2
M

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4
Q

what happens in the G1 phase?

A

cell grows

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5
Q

what happens in the S phase?

A

DNA is replicated

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6
Q

what happens in the G2 phase?

A

cell prepares to divide

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7
Q

what happens in the M phase?

A

cell division (mitosis)

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8
Q

what are the 5 different phases of mitosis?

A 
prophase
metaphase
anaphase
telophase
cytokinesis
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9
Q

what happens in prophase?

A

chromosomes condense
nuclear membrane disappears
spindle fibres form from the centriole

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10
Q

what happens in metaphase?

A

chromosomes aligned at the equator of the cell
attached by fibre to each centriole
maximum condensation of chromosomes

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11
Q

what happens in anaphase?

A

sister chromatids separate at centromere
separate longitudinally
move to opposite ends of the cell

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12
Q

what happens in telophase?

A

new nuclear membranes form

each new cell contains 46 chromosomes (diploid)

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13
Q

what happens in cytokinesis?

A

cytoplasm separates

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14
Q

what is a centromere?

A

constricted region which joins sister chromatids

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15
Q

what is the centromere composed of?

A

repetitive DNA sequences (satellite DNA)

also the site of the kinetochore

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16
Q

what is the kinetochore?

A

protein complex that binds to microtubules (involved in chromosome separation during cell division)

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17
Q

is the structure of heterochromatin condensed or open?

A

condensed (silenced)

18
Q

is the structure of euchromatin condensed or open?

A

open (active)

19
Q

what are the two tandemly repeated extragenic DNA sequences

A

satellite DNA

minisatellite DNA

20
Q

what are the two types of extragenic sequences that make up approx. 45% of the genome?

A

SINEs (short interspersed nuclear elements)

LINEs (long interspersed nuclear elements)

21
Q

what is the structure of chromatin?

A

DNA packaged with histone proteins

22
Q

are histones positively or negatively charged?

A

positively charged

23
Q

what are histones packaged into?

A

units called nucleosomes

24
Q

what is the structure of a nucleosome?

A

146 base pairs of DNA (1.8 turns) wrapped around a core of 8 histone proteins

25
Q

what does further “wrapping” of nucleosomes lead to?

A

formation of a solenoid structure, where the DNA is compacted by a factor of approx. 40

26
Q

what are the 4 levels of condensed chromatin structure?

A

1: nucleosome
2: chromatin fibre
3: fibre-scaffold complex
4: chromosome

27
Q

what are the purposes of packaging DNA?

A

negatively charged DNA neutralised by positively charged histone proteins
DNA takes up less space
Inactive DNA can be folded into inaccessible locations until required

28
Q

what is the karyotype?

A

the number and visual appearance of the chromosomes in the cell nuclei of an organism or species.

29
Q

what types of FISH probes are there?

A

unique sequence probes
centromeric probes
telomeric probes
whole chromosome probes

30
Q

what does FISH stand for?

A

fluorescent in situ hybridisation

31
Q

what is hybridisation?

A

he process of combining two complementary single-stranded DNA or RNA molecules and allowing them to form a single double-stranded molecule through base pairing.

32
Q

what is meiosis?

A

cell division in germ cells

33
Q

what creates genetic diversity in meiosis?

A

recombination of chromosomes

34
Q

what do diploid cells divide into during meiosis?

A

haploid cells

35
Q

what is oogenesis?

A

egg formation

36
Q

what is spermatogenesis?

A

process of sperm formation

37
Q

what goes through more divisions; eggs or sperm?

A

sperm - leads to a higher chance of mutation

38
Q

what is produced along with the egg in oogenesis?

A

polar bodies

39
Q

what happens in fertilisation?

A

two haploid cells form 1 diploid cell (zygote)

40
Q

what determines the gender of the child in fertilisation?

A

if the sperm contains an X or a Y chromosome

41
Q

where is mitochondrial DNA inherited from?

A

solely the mother

42
Q

what is X inactivation?

A

when an X chromosome is randomly inactivated in a female zygote

PRINCIPLES OF FUN (29 decks)

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