Mitosis and Cell Division Flashcards
(117 cards)
1
Q
Two (2) ways the eukaryotic cells divide
A
- Mitosis
- Meiosis
2
Q
Cells that undergo Mitosis
A
Somatic cells
3
Q
Cells that undergo Meiosis
A
Germ cells
4
Q
What are somatic cells?
A
Non-reproductive cells
5
Q
What are germ cells?
A
Reproductive cells
6
Q
Decrease in size or wasting away of a body part or tissue
A
atrophy
7
Q
Germ cells undergo meiosis to produce __ __.
A
Haploid gametes
8
Q
Where are germ cells found?
A
Reproductive system
9
Q
The stages of cell cycle
A
- Interphase
- Mitosis/ Meiosis
- Cytokinesis
10
Q
What are the phases in the Interphase?
A
- G1 phase
- S phase
- G2 phase
11
Q
What happens in G1 phase?
A
primary growth phase
12
Q
What happens in S phase?
A
DNA replication
13
Q
What happens in G2 phase?
A
microtubules synthesis
14
Q
What does the G in G1 and G2 phase mean?
A
Gap
15
Q
What happens in the M phase?
A
chromosomes are pulled apart
16
Q
What happens in C phase?
A
cytoplasm divides
17
Q
What is the longest stage in the cycle?
A
Interphase
18
Q
What is the shortest stage in the cycle?
A
M phase (Mitosis/ Meiosis)
19
Q
What is the intermediate stage in the cycle?
A
C phase
20
Q
The chromosomes are extended and in use
A
Interphase
21
Q
- The chromosomes condense
- Nuclear envelope breaks down
- spindle fiber forms
A
Prophase
22
Q
chromosomes line up on the central plane of the cell
A
Metaphase
23
Q
- centromeres divide
- sister chromatids separate and move toward opposite poles
A
Anaphase
24
Q
- chromosomes uncoil
- new nuclear envelope forms
- spindle fibers disappear
A
Telophase
25
cytoplasm of the cell is cleaved in half
Cytokinesis
26
- structure in a chromosome that holds together the two chromatids
- point of attachment of the kinetochore
centromere
27
cytoskeletal structure of eukaryotic cells that forms during cell division to separate chromatids
spindle fibers/ mitotic spindle (mitosis)/ meiotic spindle (meiosis)
28
one of the two identical halves of a chromosome that has been replicated in preparation for cell division
chromatid
29
Who first discovered chromosomes?
Walther Flemming in 1882
30
How many chromosomes are there in the Australian ant Myrmecia spp.?
1 pair
31
How many chromosomes are there in some ferns?
500 pairs
32
How many pairs of chromosomes do humans have?
23 pairs
33
How do chromosomes exist in somatic cells?
Exist as pairs
34
- paired chromosomes
- essentially have the same gene sequence, loci (gene position), centromere location, and chromosomal length
Homologous Chromosomes
35
have two copies of each chromosome: one from mother, one from father
diploid cells
36
Replicated chromosomes consist of __ __ __.
two sister chromatids
37
What holds the two sister chromatids together?
centromere
38
- an individual's complete set of chromosomes
- a laboratory-produced image of a person's chromosomes isolated from an individual cell and arranged in numerical order
karyotype
39
Cells wrap their DNA strands around scaffolding proteins to form a coiled condensed structure called __.
Chromatin
40
Chromatin is further folded into higher orders of structure that form the characteristic shape of __.
Chromosomes
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Components of a chromatin
~40% Complex of DNA
~60% proteins
42
How many nucleotides does a typical human chromosome contain in its DNA?
about 140 million
43
What is the equivalent of the 140 million nucleotides in the DNA of a human chromosome?
- about 5cm in stretched length
- 2,000 printed books of 1,000 pages each
44
Components of a nucleosome
- DNA
- Central histone
45
What do you call the 30nm spiral of wrapped nucleosomes?
Solenoid
46
How many sister chromatids do a replicated chromosome consist of?
2 sister chromatids
47
Difference between sister and non sister chromatids
Sister chromatids - common centromere
Non sister chromatids - different centromeres
48
The two types of nitrogenous bases
- Pyrimidines
- Purines
49
What comprises the pyrimidines?
- Cytosine
- Thymine
- Uracil
50
What comprises the purines?
- Adenine
- Guanine
51
Supports chromatin loops
Scaffold proteins
52
packaging proteins of DNA
Histones
53
What comprises the mitotic spindle?
- polar fibers
- kinetochore fibers
54
patch of protein found on the centromere of each chromatid
kinetochore
55
cell division that produces egg and sperm
Meiosis
56
contain half the complement of chromosomes found in other cells
Gametes
57
Fusion of gametes is called ___ or ___
- fertilization
- syngamy
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fertilization creates the __
zygotes
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involves the alternation of meiosis and fertilization
sexual reproduction
60
does not involve fertilization
asexual reproduction
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portion of DNA that control traits
genes
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These contain one set of chromosomes
- sperm
- egg cell
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This contains two sets of chromosomes
zygote
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Meiosis consists of two __ __, but only one __ __
Two successive divisions, but only one DNA replication
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What division happens in Meiosis I?
Reductional Division
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What division happens in Meiosis II?
Equational Division
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separates the homologous pairs
Meiosis I
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separates the two sister chromatids of each chromosome
Meiosis II
69
Stages of Meiosis I
- Prophase I
- Metaphase I
- Anaphase I
- Telophase I
70
Stages of Meiosis II
- Prophase II
- Metaphase II
- Anaphase II
- Telophase II
71
- each duplicated, condensed chromosome pairs with its homologue
- homologues swap segments
- each chromosome becomes attached to microtubules of newly forming spindle
Prophase I
72
pairing of chromosomes during prophase I
synapsis
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swapping of segments of chromosomes
crossing-over
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- chromosomes are pushed and pulled into the middle of the cell
- sister chromatids of one homologue orient toward one pole, and those of other homologue toward the opposite pole
- spindle is now fully formed
Metaphase I
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- actual division of nucleus
- homologous chromosomes segregate
- sister chromatids of each chromosome remain attached from each other
Anaphase I
76
- chromosomes arrive at opposite poles
- cytoplasm divides
- two haploid cells, but sister chromatids are still attached
- completes meiosis I
Telophase I
77
Does DNA synthesis occur in Meiosis II?
No
78
What are the two main differences of Meiosis II to Mitosis?
1. Haploid set of chromosomes (in humans 1n=23 chromosomes)
2. Sister chromatids are not identical (crossing-over)
79
the point of contact, physical link, between two (non-sister) chromatids belonging to homologous chromosomes
Chiasma
80
new combination of genetic elements
recombinant chromosomes
81
What are the five (5) stages in Prophase I?
1. Leptotene
2. Zygotene
3. Pachytene
4. Diplotene
5. Diakinesis
82
- consists of the condensing of the already replicated chromosomes
- the appearance of chromosomes is likened to 'a string with beads"
- each sister chromatid is attached to the nuclear envelope and are so close together that they can be mistaken for only one chromosome
- short stage
Leptotene Stage (Leptonema)
83
one of the serially aligned beads or granules of a eukaryotic chromosome, resulting from local coiling of a continuous DNA thread
Chromomere
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- sub-stage where synapsis between homologous chromosomes begins
- these synapsis can form up and down the chromosomes allowing numerous points of contact and can be compared to a zipper structure
Zygotene Stage (Zygonema)
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facilitates synapsis by holding the aligned chromosomes together
synaptonemal complex (SC)
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After the homologous pairs synapse in Zygotene, they are either called __ or __.
Tetrads or Bivalents
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- Once a tetrad has formed, the process of crossing over and the resulting recombination can go ahead
- At this point, the sister chromatids begin to separate from each other, although the chromosomes remain attached as a pair.
Pachytene Stage (Pachynema)
88
- the two homologous chromosomes begin to migrate apart as the synaptonemal complex disintegrates between the two chromosomal arms and they begin to repel one another.
- chiasma are fully visible at this stage, so can be seen to move towards the end of the chromatids
Diplotene Stage (Diplonema)
89
The movement of chiasmata at the tip of the chromosome due to condensation
terminalization
90
- the chiasmata connections arrive at the ends of the chromatid arms of the chromosome
- chromosomes are very condensed and still connected by chiasmata
Diakinesis
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What causes andropause?
reduction of hormones (testosterone and dehydroepiandrosterone)
92
a form of the resting state in which cells reside until they receive appropriate signals stimulating them to re-enter and progress through the cell cycle
G0 phase
93
When does the no crossing-over happens?
Prophase II
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the haploid cell which is formed by the meiosis in spermatocytes
spermatid
95
Spermatids mature and develop into __ or __
spermatozoa or sperms
96
What is the process wherein spermatids mature into sperms?
Spermiogenesis
97
a cell in an ovary which may undergo meiotic division to form an ovum
oocyte
98
cell giving rise to sperm
spermatocyte
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process of formation of female gametes
oogenesis
100
Spermatogenesis produces __ haploid sperm cells
4 haploid sperm cells
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Oogenesis produces __ mature ovum
one mature ovum
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byproduct of an oocyte meiotic division
polar body
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sexual reproduction increases genetic diversity
evolutionary consequences of sex
104
What are the three (3) mechanisms that increase genetic diversity?
1. Independent assortment
2. Crossing over
3. Random fertilization
105
way that homologous chromosomes line up on metaphase plate is random
Independent Assortment
106
What percentage is the chance that a given member of pair will end up going to a given daughter?
50% chance
107
As a result of random alignment, the number of possible combinations of chromosomes in a gamete is __.
2^n
108
What does the n in 2^n signify?
number of chromosome pairs
109
What is the possible chromosome combinations in humans?
approximately 8 million (8,388,608)
110
- DNA exchanges between maternal and paternal chromatid pairs
- adds even more recombination to independent assortment
Crossing over
111
- zygote is formed by the union of two independently produced gametes
random fertilization
112
What are the possible combinations in an offspring of random fertilization?
more than 70 trillion (70,368,744,177,664)
- does not count crossing-over
113
Why is generating diversity important?
it is the raw material that fuels evolution
114
No genetic process generates diversity more quickly than __ __.
sexual reproduction
115
What is the two (2) unique features of meiosis?
1. Synapsis
2. Reduction division
116
homologous chromosomes pair all along their lengths in meiosis I
synapsis
117
- no chromosome duplication between the two meiotic divisions
- produces haploid gametes
reduction division
