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Biology IB YR12-13 > D2.1 Cell & Nuclear Division > Flashcards

D2.1 Cell & Nuclear Division Flashcards

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1
Q

what is the result of a single cell undergoing cycles of cell division

A

cells that make up a multicellular organism

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2
Q

parent cell

A

cell that divides to form daughter cells my mitosis or meiosis

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3
Q

daughter cell

A

cell produced when a parent cell undergoes cell division - mitosis or meiosis

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4
Q

what are the 2 types of cell division

A

mitosis and meiosis

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5
Q

cytokinesis

A

splitting of cytoplasm in a parent cell between daughters cells following division of nucleus

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6
Q

nuclear division

A

when the nucleus divides first during cell division

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7
Q

how does cytokinesis occur in animal cells

A

cleavage furrow is formed which separates daughter cells

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8
Q

where is a cleavage furrow formed

A

equator or centre of cell and pinches cell membrane together to split cytoplasm

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9
Q

when does a cleavage furrow form

A

when actin and myosin proteins form a contractile ring under plasma membrane

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10
Q

role of Golgi apparatus In cytokineses

A

forms vesicles of new cell wall materials which collect at equator or cell plate

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11
Q

how does cytokinesis occur in plant cells

A

when cell plate reaches cell wall of parent cell, new cell walls are produced

separates new daughter cells

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12
Q

what are cell plates formed off and what do they carry

A

formed of vesicles and carry carbohydrates

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13
Q

how is plasma membrane in daughter cell created

A

lipids and proteins fusing together

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14
Q

examples of unequal cytokinesis

A

oogenesis
spermatogenesis
budding in yeast

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15
Q

sizes of cytoplasm during cytokinesis

A

usually equal
with at least 1 mitochondria and 1 chloroplast

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16
Q

oogenisis definition

A

egg production in humans

one egg is formed as well as several small cells that don’t go forward with fertilisation

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17
Q

oocyte

A

immature egg cell - ovum

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18
Q

steps of oogenesis briefly

A

primary oocyte division to form one small polar body which is mainly just cytoplasm and a secondary oocyte which is the main one

division occurs again in both and total of 3 polar bodies and one ovum

polar bodies merge with ovum to form one big egg cell

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19
Q

why does ovum need a large cytoplasm

A

to provide nutrients and energy for the growing embryo

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20
Q

mitosis and meiosis purpose

A

division of nucleus of cell in eukaryotic cell

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21
Q

anucleate

A

cell without a nucleus

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22
Q

why is it important for nucleus of a cell to divide before cell division

A

to avoid production of anucleate cells

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23
Q

mitosis definition

A

daughter nuclei have the same number of chromosomes as the parent cell

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24
Q

what is mitosis used for

A

growth, repair of damaged tissues, replacement of cells and ASEXUAL reproduction

maintains chromosome number and genome of cells

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25
Q

diploid

A

cells with nuclei containing 2 sets of chromosomes

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26
Q

cells produced in mitosis will be —-

A

diploid

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27
Q

meiosis definition

A

daughter cell containing half the number of chromosomes of the parent cell

one chromosome of each parent present in nuclei

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28
Q

cells produced in meiosis will be —-

A

haploid

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29
Q

meiosis used

A

production of gametes - sperm and egg
generating genetic diversity

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30
Q

haploid notation

A

n

31
Q

diploid notion

A

2n

32
Q

interphase definition

A

the period between the nuclear divisions
replication of chromosomes takes place

33
Q

phases in interphase

A

gap 1, gap 2, synthesis

34
Q

chromatid

A

one of 2 copies of a chromosome after it has replicated, jointed together at centromere

35
Q

centromere

A

constriction of chromosome, the region that becomes attached to the spindle fibres during nuclear division

36
Q

condensation of chromosomes brief explanation

A

dna molecules are too long and need to fit in small nuclei

they become condensed by supercoiling to form chromosomes

37
Q

how does condensation of DNA occur

A

through repeated coiling of dna molecule

38
Q

histone protein role

A

packages dna into nucleosomes

39
Q

how is supercoiling aided

A

is aided in eukaryotic cells by histone protiens and enzymes

40
Q

histone definition

A

protiens that forms the structure of chromosomes and is used in chromosome condensation to form nucleosomes

41
Q

nucleosomes definition

A

basic unit of eukaryotic chromosome structure, consisting of a ball of 8 histone protein molecules wrapped about by 2 coils of DNA

42
Q

supercoiling

A

form of DNA in which the double helix is further twisted about itself within nucleosomes.

forming tightly coiled structure

43
Q

how to chromosomes move during division

A

microtubules and microtubule motors move them

44
Q

microtubules

A

tubular fibres that form part of the cytoskeleton of the cell

lengthen and shorten in order to make the chromosomal movement

45
Q

4 main phases of mitosis (PMAT)

A

prophase
metaphase
anaphase
telophase

46
Q

prophase simple

A

first stage where chromosomes condense

centrosomes move towards opposite poles

spindle fibres emerge from centrosomes

nuclear membrane breaking down into smaller vesicles

nucleolus dissapears

47
Q

metaphase simple

A

centrosomes reach opposite poles
spindle continue to extend

chromosomes line at equator of spindle
spindle fibres reach chromosome and attach to centrosomes
- kinetochores

each sister chromatid is attached to a spindle fibre originating from opposite poles

48
Q

anaphase simple

A

sister chromatids separate at centre

spindle fibres shorten
chromosomes pulled to opposite poles by spindle fibres

49
Q

telophase simple

A

chromosomes at opposite poles and start decondensing

nuclear envelopes begin to reform around each set of chromosomes

spindle fibres break down

new nuclei form within each nucleus

50
Q

meiosis phases

A

meiosis 1 and 2

51
Q

what happens during m1

A

homologous pairs of chromosomes split to produce 2 haploid nucleus

52
Q

how many chromatids in one chromosome

A

2

53
Q

chromosome number in m1

A

halves from 2n to n in M1 -> reduction division

54
Q

homologous chromosomes

A

pairs of chromosomes in a diploid organism that have similar genes, although not necessarily identical

55
Q

bivalent

A

pair of homologous chromosomes held together by chiasma

56
Q

chiasma

A

site of crossing over of segments of DNA between homologous chromosomes or non sister chromatids

57
Q

crossing over

A

exchange of genetic material between bivalents

occurs between non-sister chromatids

results in a new combination of alleles on the 2 chromosomes

58
Q

recombinant chromosomes

A

chromosomes which have been genetically changed due to crossing over

59
Q

M2

A

between m1 and m2 no interphase

during m2 - chromatids separate to produce 4 haploid nuclei

each chromosome consists of a single chromatid

60
Q

non disjunction occurs

A

occurs when chromosomes fail to separate correctly during meiosis

can occur in anaphase 1 or 2

61
Q

non disjunction leading to

A

gametes being formed with an abnormal number of chromosomes

may end up with one extra copy of a particular chromosome or no copies of a particular chromosome

62
Q

what happens if abnormal gametes are fertilised

A

chromosomes abnormality occurs as the diploid cell will have the incorrect numbers of chromosomes

63
Q

example of non disjunction chromosome abnormality

A

Down syndrome or trisomy 21

64
Q

what happens in Down syndrome

A

total of 47 chromosomes rather than 46

they have 3 copies of chromosome number 21

65
Q

what is the impact of trisomy 21 or Down syndrome

A

varies between individuals
common features - physical growth delays
reduced intellectual ability
issues with sight or hearing

66
Q

where else can trisomy 21 occur

A

in chromosomes 18 and 13

67
Q

non disjunction definition

A

the failure of homologous chromosomes or sister chromatids to separate properly during meiosis

68
Q

down syndrome definition

A

a congenital condition in which a person has an extra chromosome 21 as a result of non disjunction

69
Q

karyotyping definition

A

a process which makes a diagram (karyotype) of chromosomes descending in size

70
Q

karyotyping use

A

can be used to identify chromosomal abnormalities

71
Q

how is genetically different offspring advantageous

A

for natural selection
increase in survival of species - evolving and adapting

genetic variation in populations of sexually reproducing species

72
Q

what causes genetic differentiation

A

crossing over
mothers and fathers genes are exchanged into each others chromosomes

73
Q

random orientation

A

orientation of bivalents when they line up at the cell equator (M1) determines which pole each chromosome gets attached to

74
Q

combination formula

A

2^n

Biology IB YR12-13 (26 decks)

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