Flashcards in 2.6 cell division, diversity and cellular organisation Deck (46)
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1
the stages of the cell cycle are
mitosis, cytokinesis, interphase
2
many cells in multicellular tissues don't have the ability to
divide
3
during interphase, cells are
between dividing
4
during mitosis, cells are
dividing and moving to opposite poles of the cell
5
during cytokinesis, cells are
splitting in two
6
the stages of interphase are
G1, S, G2
7
G1 is known as the
growth phase
8
the purpose of G1 is to
prepare the cell for mitosis
9
3 things that happen during G1 are...
1. organelles duplicate
2. cell grows in size
3. proteins needed for mitosis are made
10
S phase is also known as the
synthesis phase
11
the purpose of S phase is to
replicate DNA so that there are 2 sets for the new cells
12
by the end of S phase, all chromosomes
have been replicated
13
during S phase, all - are replicated
DNA strands
14
the purpose of G2 phase is to
check that the cell is ready for mitosis
15
what happens in G2 phase
organelles such as mitochondria and lysosomes divide
16
meiosis is used to create
haploid cells
17
meiosis occurs in
two divisions
18
diploid cells have - pairs of chromosomes
23
19
haploid cells can be called
gametes
20
why do gametes have to be haploid?
so that they have the right number of chromosomes when they grow alongside another gamete in sexual reproduction
21
meiosis occurs
after interphase
22
what happens in meiosis 1?
homologous pairs of chromosomes are separated
23
what happens in meiosis 2?
sister chromatids from each chromosome are separated
24
meiosis creates - - gametes which are - -
4 haploid, genetically different
25
what are the stages in meiosis 1
prophase 1, metaphase 1, anaphase 1, telophase 1
26
prophase 1 is the first...
stage in meiosis overall
27
during prophase 1, chromosomes
supercoil to condense, making them visible
28
during prophase 1, the nuclear envelope
breaks down
29
during prophase 1, spindle fibres
form from centrioles
30
4 things that happen during prophase 1
1. chromosomes supercoil
2. nuclear envelope breaks down
3. spindle fires form from centrioles
4. chromosomes undergo crossing over
31
when does crossing over occur?
during prophase 1
32
crossing over is the...
exchange of DNA between chromatids on homologous chromosomes
33
the stages of crossing over are
1. twisting
2. breaking off
3. swapping
34
crossing over allows
variation in alleles
35
the key purpose of metaphase 1 is to
line up chromosomes at the equator of the cell
36
independent assortment occurs during
metaphase
37
independent assortment is how
homologous chromosomes are arranged
38
independent assortment creates
more genetic variation
39
3 things that happen in metaphase 1 are
1. attachment of chromosomes to spindle fibres at the centromere
2. chromosomes lie with their homologous pair at the equator
3. independent assortment
40
how do chromosomes attach to spindle fibres
at the centromeres
41
spindle fibres are constructed from
centrioles in animals, cytoplasm in plants
42
the purpose of anaphase 1 is
to separate homologous chromosomes to opposite poles of the cell
43
in anaphase 1, chromosomes are pulled to opposite poles by
spindle fibres and motor proteins
44
the purpose of telophase 1 is to
reform two new nuclear envelopes
45
which type of cell undergoes cytokinesis after telophase 1
animal cells
46
