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Biology 101 > Cell cycle and Cell Division (mitosis and meiosis) > Flashcards

Cell cycle and Cell Division (mitosis and meiosis) Flashcards

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1
Q

what is the goal of cell division

A

partition 2 identical (more-or-less) copies of genetic material between two daughter cells

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2
Q

Difference between prokaryotes and eukaryotes in cell division

A 
binary fission(pros)
mitosis (euks)
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3
Q

Why are prokaryotic cells simpler to divide

A

comparatively simple; only 1 chromosome, so have a relatively easy time sorting daughter chromosomes to daughter cells

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4
Q

why are eukaryotic cells more difficult to divide

A

longer DNA & multiple chromosomes

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5
Q

what are the steps of binary fission

A

1) Prokaryote chromosome replicates & cell stretches
2) Produce 2 circular chromosomes at opposite ends of cell

3) Cell membrane stretches & breaks apart → form 2 cells
Each cell has now has 1 full chromosome

4) Randomly distributed cytosol, plasmids, & ribosomes end up in both cells

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6
Q

what are the two methods of asexual reproduction>

A

binary fission and mitosis

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7
Q

explain loose chromatin

A

Unwound DNA
Found throughout Interphase
DNA is being used for macromolecule synthesis

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8
Q

explain condensed chromosomes

A

Tightly packaged DNA
Found only during cell division
DNA is not being used for macromolecule synthesis

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9
Q

why do eurkaryotes do mitosis?

A

they have a nucleus so dna cannot simply move to either side of the cell
they have multiple chromosomes meaning need to ensure that each daughter cell has exactly 1 copy of each chromosome

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10
Q

chromosomes are formed from what

A

2 sister chromatids with an identical sequence

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11
Q

where are sister chromatids attached

A

at the centromere

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12
Q

where to microtubules attach to?

A

The kinetochore

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13
Q

what is another name for the microtubules that split the sister chromatids

A

mitotic spindle

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14
Q

What pulls apart the sister chromatids in mitosis

A

microtubles

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15
Q

where are the two centrosomes?

A

at opposite poles of the nucleus

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16
Q

what is the centromere?

A

dna sequence that links sister chromatids

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17
Q

what are the 3 functions of the centromere?

A

adhesion
kinetochore formation
pairing of homologous pairs

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18
Q

what is the kinetochore?

A

protein structure that assembles at centromere

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19
Q

what are the functions of the kinetochore?

A

links chromosome to microtuble polymers from the mitotic spindle
used in mitosis and meiosis

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20
Q

what does the cell cycle include?

A

Includes DNA replication, cell division & cell growth

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21
Q

What are the 4 phases of the cell cycle?

A

g1 (gap phase 1)
s (synthesis)
g2 (gap phases 2)
m (mitosis)

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22
Q

explain gap phase 1 (g1)

A 
lasts approx 11h
growing
performs transcription and translation 
produces proteins and organelles
at a certain phase, s is initiated
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23
Q

explain s phase

A 
lasts approx 8h
period of dna replication
little growth occurs 
nucleus contains double the dna
once celel has replicated all its dna, g2 is initiated
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24
Q

does protein synthesis occur in s phase

A

NO not enough space/energy to do both

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25
Q

how many chromosomes do humans have

A

46 (23 pairs)

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26
Q

are the two chromosome pairs identical?

A

no because we have one copy from each parent therefore they have genetic differences
they are a homologous pair

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27
Q

why are the two chromosomes (1 from each parent) called a homologous pair

A

because although they aren’t genetically identical, they code for the same proteins (ie. hair colour, height)

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28
Q

what does the s phase entail and what does it give you

A

entails dna synthesis

gives two identical sisters chromatids attached at the centromere

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29
Q

why do we have two homologous pairs?

A

because one from mom is copied and one from dad is copied

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30
Q

explain g2 phase

A

lasts approx. 4 h
growing
produces more organelles and proteins
once a certain size, mitosis is initiated

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31
Q

why must the cell cycle be tightly regulated?

A

to ensure division does not happen prematurely or too late\ee

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32
Q

what are the proteins that regulate the cell cycle

A

cyclins

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33
Q

what do cyclines do?

A

family of proteins that regulate transition of cells from one stage of the cell cycle to the next.
Specific cyclins control transition from S to G2: send signals within the cell to know when replication is complete

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34
Q

what happens if cyclins do not functionn properly?

A

cell may go uncontrolled growth which leads to cancer

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35
Q

are all cells in the cell cycle at all times

A

no , some cells are in g0

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36
Q

are cells not going through the cell cycle considered dead>

A

no, they still transcribe and translatee

they just aren’t actively dividing

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37
Q

what are the two types of cells (Q vs D)

A

Quiescent cells vs Differentiated cells

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38
Q

explain quiescent cells

A

they are reversible and can change (skin cells)

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39
Q

explain differentiated cells

A

they can never go back (brain cells)

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40
Q

mitosis is used for what kind of cells

A

somatic (non sex cells)

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41
Q

what are the 5 phases of mitosis

A

1) prophase
2) prometaphase
3) metaphase
4) anaphase
5) telophase

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42
Q

components of prophase

A

nucleoli disappears and dna condenses (see thick visible lines, dna is no longer long unravelled fibres)
sister chromatids are attached at centromere
kinetochore proteins attaches to centromere

centrosomes (that we’re replicated) seperate and migrate to oppsotive sides of the cell
microtubles extend and attach to each other and as these grow, the cell stretches

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43
Q

what is the centrosome

A

microtubule organizing centre

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44
Q

components of prometaphase

A

nuclear envelope breaks down
spindles fibbers attach to kinetochore
other spindle fibres extend to provide tracks for migrateing organelles

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45
Q

components of metaphase

A

chromosomes align at cell equator (metaphase plate) in nice row
kinetochores of sister chromatids are facing opposite poles (each attached to a spindle from different sides of cell)

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46
Q

components of anaphase

A

sister chromatids are pulled apart (each now considered a daughter chromosome)
microfibres (spindles) shorten
cell elongates
each pole has.a copy of each chromosome

47
Q

components of telophase

A

nuclei begin to form at each pole
nuclear envelope forms around chromosomees
chromatin uncoils/decondenses and become less distinct

48
Q

what is the last process of mitosis called

A

cytokinesis

49
Q

what is the goal of cytokinesis

A

separation created two identical daughter cells)

50
Q

explain cytokinesis in animals

A

formation of cleavage furrow (growing gap between two daughter cell)
pinching in caused by microfilaments inside cell which tightens til cell splits

51
Q

explain cytokinesis in plants

A

plants have cell wall therefore cannot do cleavage furrow
must form cell plate that will form with cell wall then divide
vesicles from golgi bring small pieces of cell wall

52
Q

difference between animal and plant mitosis

A

1) cleavage furrow vs cell plate

2) animals have centrioles, plants do not

53
Q

aspects of asexual reproduction

A
  • reproduction without sex
  • binary fission or mitosis
  • involves only one parent
  • offsprings are genetically identical (clones) or parent
54
Q

aspects of sexual reproduction

A
  • union of 2 gametes (sex)
  • meiosis and fertilization
  • involved 2 parents
  • offspring are genetically different from parents (recombination)
55
Q

mitosis creates what kinds of cells

A

diploid somatic cells

56
Q

meiosis creates what kinds of cells

A

haploid gametes

57
Q

meiosis creates how many daughter cells and are they identical

A

makes 4 cells which are genetically similar but still different

58
Q

what is a somatic cell and what kinds are somatic

A

Non-reproductive cell

Almost all the cells in your body are somatic cells (except sperm / eggs)

59
Q

what is a gamete and where are they produced

A 
Reproductive cells (e.g. eggs / sperm)
Produced in ovaries / testes through meiosis
60
Q

haploids are human…

A

gametes

61
Q

diploids are human…

A

somatic cells

62
Q

what is a haploid cell

A

cell that possesses one set of chrmosomes

63
Q

what is a dimploid cell

A

cell that possesses two sets of chromos

when u inherit one set from each parent

64
Q

define sex chromosome

A

Determine sex (dissimilar chromosomes – not homologous)
Humans: X & Y chromosomes
Humans have 1 pair of sex chromosomes (XX or XY)

65
Q

are sex chromosomes homolgous?

A

no

66
Q

define autosome

A

Any chromosome that is not a sex chromosome

Humans have 22 pairs

67
Q

define homologous chromosomes

A

Pair of chromosomes with the same size, centromere position, staining pattern
Inherit 1 homologue from each parent
Autosomes: same genetic loci (sites) – code for same genes
Note: sex chromosomes have different sizes & loci (X vs. Y) but they do pair during meiosis

68
Q

define karyotype

A
  • Shows chromosomes in a somatic cell at metaphase
  • Arranged in a standard sequence (size, centromere location, colours from staining)
  • Use to screen for chromosomal abnormalities
69
Q

meiosis forms what in comparison to mitosis

A

Meiosis forms 4 unique haploid cells

Compare this to mitosis, which forms 2 identical diploid cells

70
Q

components of meiosis 1 prophase 1

A

chromosomes condense
sister chromatids associated with one another
homologous pairs also associate
centrosomes extend microtubules and move apart

71
Q

explain homologous recombination

A

homologous chromosomes (non sisters) can cross over and recombine

72
Q

where does recombination occur

A

chiasmata

73
Q

what is the result of meiosis prophase1

A

4 chromatids cluster around centromere (tetrad is formed)
(pair of homologous chromosomes)
associate with a kinetochore

74
Q

components of meiosis 1 pro metaphase 1

A

nuclear envelope breaks down
tetrads associate to mitotic spindle fibers
centrosomes localist to opposite poles of the cell

75
Q

components of meiosis 1 metaphase 1

A

tetrads align at centre of cell (metaphase plate/equator)
kinetochores of homologous chromosomes face opposite cells (Each attached to a spindle fibre originating from a different side of the cell)

76
Q

components of meiosis 1 anaphase 1

A
  • pairs of sisters chromatids REMAIN ATTACHED (ie. sister chromatids do not separate yet to go to a different centrosome)
  • each homologous chromosome pair DOES separate from its other pair memeber
77
Q

what is the result of anaphase 1

A

one copy of each chromosome is passed to a different cell (this is a random choice)
-daughter cells are haploid because despite having.2 sister chromatids they are lacking one different copy from each chromosome)

78
Q

in anaphase 1, are you supposed to have both a copy from mom and dad?

A

no, it will either be one copy from mom OR. a copy from dad

79
Q

components of meiosis 1 teleophase 1

A

sister chromatid pairs reach the centrosome

some cells show chromosome decondensing, some dont

80
Q

components of meiosis 1 cytokinesis/interkinesis 1

A

formation of cleavage furrow (like mitosis)
pinching caused by microfilaments
more centrosomes are produced for meiosis round 2

81
Q

components of meiosis 2 prophase 2

A

almost identical to meosis 1 except tetrads to not form since there are not homologous chromosome pairs (only have pairs of sisters chromatids)

82
Q

components of meiosis 2 pro metaphase 2

A

nuclear breaks apart again (if it has reformed)
pairs of sister chromatids attach to spindle fibres via centromeres
centrosomes go to opposite poles of cell

83
Q

components of meiosis 2 metaphase 2

A

chromosomes align at metaphase plate
kineetichores face opposite sides attached to a spindle from different side of cell)
just like mitosis except sister chromatids may not be identical due to recombination

84
Q

components of meiosis 2 anaphase 2

A

sister chromatids seperate and move to opposite centrosome
(separated sisters are now considered to be individual chromosomes)
these cells are already haploid but this seperation ensures only 23 chromosomes per game)

85
Q

components of meiosis 2 telophase 2

A

chromos research centrosomes at each pole

nuclei reforms and dna decondenses

86
Q

cytokinesis 2

A

same as cytokinesis 1

but now we have 4 daughter cells1

87
Q

meiosis recap

A

2 rounds of chromosome seperation and cell division
forms 4 unique haploid cells
end up with only 1 copy of each chromosome in a single gamete

88
Q

components of meiosis in males

A

Spermatogenesis (formation of sperm)
Primary spermatocytes undergo meiosis I
Produce 2 secondary spermatocytes
Secondary spermatocytes undergo meiosis II
Produce 4 different spermatids
Spermatids are modified so they can survive the journey needed to achieve zygote formation

Result: produce 4 distinct mature spermatocytes (“sperm cells”)

89
Q

what is the process of meiosis called in males

A

spermatogenesis

90
Q

what is the process of meiosis called in females

A

oogenesis

91
Q

process of meiosis in females

A

Primary oocyte undergoes meiosis I
Produce secondary oocytes

Larger secondary oocyte (non-polar body) is destined to become an egg cell (gamete)
Stores much larger portion of cytosol & cellular organelles
Smaller secondary oocyte (polar body) will eventually be eliminated

Larger secondary primary oocyte undergoes meiosis II
Produces 2 more cells from the non-polar body - also different sizes
Larger cell is the mature oocyte (mature ovum)
Mature ovum will fuse with mature sperm cell to produce a zygote

92
Q

what is the difference between the two oocytes?

A

1 secondary oocyte is larger than the other

93
Q

what does the process of oogenesis create?

A

1 mature ovum

3 polar bodies

94
Q

meiosis in human females (table)

A
  • All oocytes are made before birth
  • Meiosis is completed only if the egg is fertilized
  • 1 large egg & 3 other small cells (polar bodies) are the result of one oocyte undergoing meiosis → the polar bodies die
  • Egg has half the DNA of a normal body (somatic) cell.
  • Egg’s diameter is 140 mm or larger
  • Egg has enormous cytoplasmic storehouse of proteins, ribosomes, tRNA, mRNA (25,000-50,000 different types of mRNA), & morphogenetic factors.
95
Q

meiosis in human males (table)

A
  • Spermatocytes are made under the influence of testosterone, starting at puberty, and continuing throughout life
  • Meiosis is completed before sperm leave the testes (within the seminiferous tubules).
  • 4 small equal-sized functional cells are formed during and after meiosis.
  • Sperm has half the DNA of a normal body (somatic) cell.
  • The sperm’s head is about 5 mm

Sperm designed for specialized function:

  1. locating the egg
  2. fusing with the surface of the egg
  3. injecting the sperm nucleus (DNA) into the egg cell’s cytoplasm.
96
Q

what are the 3 sperm functions

A
  1. locating the egg
  2. fusing with the surface of the egg
  3. injecting the sperm nucleus (DNA) into the egg cell’s cytoplasm.
97
Q

what are the three ways of introducing genetic variation during meiosis

A

1) independant assortment
2) random fertilization
3) recombination

98
Q

explain independent assortment

A

decision of which chromosome goes to while cell is completely random
approx (8.3 million combos)

99
Q

explain random fertilization

A

there are so many possibilities as to which games will fuse (70 trillion combos)

100
Q

how is a zygote formed?

A

fusion of two games (egg and sperm)

101
Q

explain recombination?

A

Homologous chromos (non sisters) can cross over and form chiasmata

both strands of dna trade fragments of the chromosomes so sisters are no longer identical

102
Q

what is is called when something goes wrong in cell division

A

non-disjunction

103
Q

What is an aneuploidy

A

cell that ends up with the wrong number of chromos

104
Q

what happens in a non disjunction

A

when seperation of chromatids or chromosomes does not occur meaning some gametes will have too many chromes and some will have too few

105
Q

when can a non disjunction happen

A

anaphase in either meiosis 1 or 2

106
Q

what happens when a non disjunction occurs during meiosis 1?

A

entire tetrad migrates towards 1 centrosome

All 4 gametes affected

107
Q

what happens when a non disjunction occurs during meiosis 2?

A

both sister chromatids migrate towards 1 centrosome
2 of 4 gametes affected
DIAGRAM I NSLIDES

108
Q

will an XYY male show any differences from a normal XY male?

A

no

109
Q

will an XXX female show any differences from a normal XX female?

A

no

110
Q

what are the 4 common conditions caused by aneuploidy

A

Down Syndrome:
Edwards Syndrome
Klinefelter Syndrome:

Turner Syndrome:

111
Q

explain down syndrome

A

have 3 copies (“trisomy”) of chromosome 21
As a result, have 47 chromosomes
Leads to a large # of physical differences & intellectual disability

112
Q

explain edwards syndrome

A

(trisomy of chromosome 18) & Patau Syndrome (trisomy of chromosome 13) are 2 other relatively frequent cases of trisomy in humans
Both have increased mortalities associated with them.

113
Q

explain klinefelter syndrome

A

males with an additional copy of the X chromosome (XXY or even XXXY)
Display a cross between male and female traits (small testes, enlarged breasts, reduced facial hair) and tend to be infertile
Associated with learning difficulties & co-ordination problems

114
Q

explain turner syndrome

A

females with only 1 copy of the X chromosome (X)
Only non-lethal case of monosomy in humans
Have distinct body frames (certain regions are underdeveloped, including reproductive organs)

Biology 101 (15 decks)

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