Cell Division Flashcards
(161 cards)
1
Q
what does monosomy cause
A
the gamete is missing one or two chromosomes of a homologous pair
2
Q
what are microtubules
A
hollow tubes of protein that facilitate movement of chromosomes within a cell
3
Q
what is the second phase of mitosis
A
metaphase
4
Q
how is each phase of mitosis identified
A
by the appearance or disappearance of other cell structures and by a particular arrangement of chromosomes within the dividing cell
5
Q
what happens to primary oocytes after puberty
A
each month one undergoes meiosis
6
Q
what are identical twins
A
twins resulting when a single zygote divides into two seperate cell masses during embryonic development
7
Q
when does telophase begin in mitosis
A
when the chromatids have reached the opposite poles of the cell
8
Q
define meiosis I
A
the first of two sequences in meiotic cell division in which the chromosomes are reduced from diploid to haploid
9
Q
define binary fission
A
asexal reproductive process of cell division in bactera and other prokaryotes that produces geneticaly identical populations
10
Q
what is cytokinesis
A
division of the cytoplasm to complete the creation of two new daughter cells
11
Q
how many copies of chromosomes does each diploid germ cell contain
A
two copies of each chromosome
12
Q
what happens in prophase I of meiosis
A
- each pair of homologous chromosomes align side by side in synapsis and pair up
13
Q
define budding
A
asexual form of reproduction wherby a new organism develops as an outgrowht of the body of the parent
14
Q
whats a pilus
A
extensions of a bacterial cell enabling it to transfer genetic materials from one individual to antoehr through the process of conjugation
15
Q
ture or false: organisms are only capable of sexual or asexual reproduction
A
false; many are capable of both
16
Q
define spermatogenesis
A
the process of male gamete/sperm production in animals
17
Q
what happens in prophase of mitosis (4)
A
- chromatin condenses into tightly paced visible chromosomes
- nuclear membrane breaks down and releases the chromosomes into the cytoplasm
- nucleolus disappears
- one pair of centrioles move apart ot opposite poles of the cell and a spindle apparatus forms between them
18
Q
define begetative reproduction
A
a form of asexual reproduction in which a new plant grows from a modified plant
19
Q
whats synapsis
A
aligning of homologous chromosomes side-by-side during prophase I in meiosis
20
Q
what are fraternal twins
A
twins resulting from the simultaneous fertilization adn implantation of two eggs
21
Q
true or false: mitosis is a continuous cycle of events in living cells
A
true; it is a continuous cycle making it so that there are no clear dividing lines between one event to the enxt
22
Q
define sexual reproduction
A
reproduction involving meiosis, gamete formation and fertilization
23
Q
how is it possible that a zygote has the same number of chromosomes as the parent organism
A
the organisms gametes contain half the number of chromosomes as the somatic cells of the organism
24
Q
what are germ cells
A
gamete producing cell in the male and female gonads
25
what is the fourth and final phase of mitosis
telophase
26
are all spores the product of asexual reproduction
no, some organisms produce spores by meiosis which results in an alternation of generations
27
what is the third phase of mitosis
anaphase
28
whats an example of monosomy
turner syndrome
29
what are the three main important functions of the linked process of mitosis and cytokinesis
- growth
- maintenance
- repair
30
true or false: even though all plant life cycles include two generations, one of them will be characteristically dominant over the other
true
31
what happens during anaphase I of meiosis (3)
- the spindle fibres shorten which causes the homologous chromosomes to separate from one another
- the homologous chromosomes move to opposite poles of the cell
- the sister chromatids are still held together so they do not split resulting in a single chromosome made up of two sister chromatids from each homologous pair moving to each pole of the cell
32
define meiosis II
the second of two sequences in meiotic cell division in which each of the haploid cells created during meiosis I undergo mitosis without an interphase
33
what is a tetrad made up of
a pair of sister chromatids that synapsed with another pair of sister chromatids
34
what happens to spermatids following meiosis II
they go through a final set of developmental stages ikn order to develop into mature sperm
35
define conjugation
a process of reproduction in microorganisms that involves the transfer of genetic material from one cell to another by cell-to-cell contact through a bridging structure called a pilus
36
how does a spore work
it contains genetic material and cytoplasm surrounded by a protective sheal or wall that protects the contents until conditions are favourable. when conditions are favourable the wall opens and organism begins to develop
37
are the cells produced by meiosis haploid or diploid
haploid
38
what are the cells produced by asymmetrical cytokinesis called
the one with the most cytoplasm is called the secondary and the other cell is the first polar body
39
whats in the middle of a tetrad
two homologous but non-identical chromatids that lie side by side
40
true or false: cells that enter meiosis II still consist of replicated chromosomes
true
41
what happens to the cell that contains the least cytoplasm after the seoncdary oocyte undergoes meiosis II
it becomes the second polar body and is not a viable gamete
42
whats a spindle apparatus
assembly composed of spindle fibres that are assembled during prophase that carries out the separation of chromosomes during cell divison
43
what happens when cell division isnt controlled
a fast growing mass of non-functional cells develop and cancer happens
44
what do primary spermatocytes undergo and what does this form
meiosis I to form two secondary spermatocytes
45
true or false: interphase is different in mitosis and meiosis
false; germ cells proceed thorugh the growth and synthesis phases of interphase before dividing the same as somatic cells
46
define alternation of generations
a term describing the life cycle of a plant that alternates between a diploid sporophyte generation and a haploid gametophyte generation
47
how do spindle fibres attache to the centromeres of chromosomes in metaphase I
a spindle fibre from one pole attaches to one pair of sister chromatids in the tetrad and a spindle fibre from the opposite pole attaches to the other pair of sister chromatids
48
what happens during telophase of mitosis (3)
- Chromatids begin to unwind into the longer and less visible strands of chromatin
- spindle fibres break down
- a nuclear membrane is formed around each new set of chromosomes and a nucleolus forms within each new nucleus
49
what three things happen to spermatids during their final set of development stages
- nucleous and certain enzymes are organized into a head region
- the midsection holds many mitochondria which serve as an energy resource for the cell
- a long tail like flagellum develops for locomotion
50
what type of cell division is involved in spermatogenesis and oogenesis
meiosis
51
what process are the daughter cells in after the seperate in cytokinessis
G1 stage of interphase
52
what are some things that contribute to regulating when a cell divides (4)
- specific protein interactions serve as start or stop signals for cell division
- presence of particular hormones
- availability of nutrients
- contact with other cells
53
what does spermatogenesis start with
a diploid germ cell called a spermatogonium
54
what are 3 methods of saexual reproduction
budding, vegetative reproduction, fragmentation
55
what two processes are constantly occuring in the testes and why
- mitosis in order to keep a supply of germ cells for gamete production
- meiosis becuase hundreds of millions of sperm are relased in a single ejaculation
56
define sporophyte
a diploid generation of a plant that produces haploid spores through meiosis that develop without fertilization into a gametophyte
57
what are spermatids
each of four haploid cells that result whena secondary spermatocyte undergoes meiosis II
58
what does oogenesis start with
a diploid germ cell called an oogonium
59
what causes turner syndrom
when an x chromosome is missing so the female sexual characteristics will be underdeveloped
60
what happens in metaphase of mitosis (2)
- spindle fibres guide the chromosomes to the equator/center line of the cell
- the spindle fibres from opposite poles attach to the centromere ofe ach chromosome in a way that one sister chromatid faces one pole with the other sister chromatid faces the opposite pole
61
what causes nondisjunction in anaphase I of meiosis
when homologous chromosome pairs do not separate to opposite poles but instead one entire pair is pulled towards the same pole together
62
how many main phases does mitosis have
4
63
What is formed during sexual freproduction and how
a zygote that has genetic information from both parents due to the fusion of a gamete from the male and a gamete from the female
64
what does binary fission and somatic cell replication in humans have in common
binary fission still involves the cell replicating its DNA and then distributing one complete copy of its DNA into each of two identical daughter cells
65
true or false: homologous chromosomes are identical
false; even though they carry the same genes they are not identical because they carry different alleles of these genes
66
what are individuals with down syndrome born with
extra chromosome 21
67
what does the life cycle of all plants consists of
a haploid and a diploid generation that alternate
68
what does the unequal division of cytoplasm in oogenesis mean in regards to the amount of gametes produced
only one egg cell is produced following meiosis I and II instead of the 4 viable gametes produced by the end of spermatogenesis
69
whats an example of trisomy
down syndrom
70
define fragmentation
a form of asexual reproudction in which a new organism is created from a fragment/portion of a parent organisms
71
what are vascular plants
plants that have a transport system of conduction tubes
72
whats a cell plate
structure across a dividing plant cell that signals the location of new plasma membranes and cell walls
73
what is a result of crossing over
individual chromosomes will contain some genes of maternal origin and some genes of paternal origin
74
whats it called when one chromosome is lost as a result of nondisjunction
monosomy
75
what are some differences between cell division in plants and animals that occur due to structural differences (3)
- plant cells do not have centrioles mbut they do form a spindle apparatus
- the rigid cell wall of a plant cell is much stronger than the membrane of an animal cell
-the cell wall of a plant does not furrow and pinch in during cytokinesis but a cell plat forms between the two daughter nuclei to seperate them
76
how does cytokinesis end
with the seperation of two genetically identical daughter cells
77
what is different about how chromosomes line up during metaphase in mitosis vs metaphase I in meiosis
in meiosis they do not line up in single file as they do in mitosis but instead line up as homologous pairs
78
what happens in metaphase I
- a spindle fibre attaches to the centromere of each chromosome and guides each tetrad to the equator of the cell
79
in general, what does the different meiotic processes result in
the production of sperm and eggs
80
what do the cells contain structrually at the end of meiosis II
the daughter cells are still haploid and contain single unreplicated chromosomes
81
what are 4 potential advantages to sexual reproduction
- offers a population a way to adapt to a changing environment
- competition among siblings may be reduced if they are genetically diverse
- pairing of homologous chromosomes and crossing over have the opportunity to replace or repair damaged chromosomes
- offers an opportunity for genetic variation
82
what type of growth pattern does binary fission result in
exponential growth
83
define non sister chromatids
the chromosomes in a tetrad that do not belong to the same chromosome and undergo crossing over during prophase I of meiosis
84
what is teh key mechanism involved in asexual reproduction
mitosis
85
what process comes after mitosis/nuclear division
cytokinesis
86
what can the cell created by conjugation undergo
binary fission to create a colony of cells
87
what is the order of the phases that occur in mitosis
prophase, metaphase, anaphase, telophase
88
what happens during cytokinesis (4)
- an indentation forms in the cell membrane along the equator
- the indentation deepens until the cell is pinched in two
- the cytoplasm and organelles divide equally between the two halves of the cell
- separation of two genetically identical daughter cells occurs
89
whats the only way conjugation can take place
when its between non-identical bacterial cells
90
whats a secondary oocyte and what does it become
the cell that receies the larger portion of cytoplasm when a primary oocyte undergoes asymmetrical cytokinesis during meiosis I causing it to become the egg
91
what does down syndrome cause (4)
characteristics such as impairment of physical growth, below average cognitive ability, development of certain physical features such as almond shaped eyes and an enlarge tongue, increases risk of congenital heart defects in infants
92
define meiosis
the cellular process that produces haploid gametes from diploid cells in the ovaries and testes
93
what are secondary spermatocytes
each of two cells produced as a result of primary spermatocyte undergoing meiosis I
94
true or false: when the secondary oocyte undergoes meiolsis II the cytoplasm will be equally divided
false, it will again be unequally divided
95
how many nucelar divisions are involved in meiosis
2
96
what does conjugation create and why is this beneficial
cells with new genetic combinations which provides a chance that some cells may be better adapted changing conditions
97
how do bacterial cells reproduce and why
through binary fission because they have a single circular chromosome and no nucleous
98
what is crossing over
the process by which non-sister chromatids exchange genes during prophase I of meiosis allowing for the recombination of genes
99
when does crossing over occur
during prophase I of meiosis when non-sister chromatids are lined up
100
what causes nondisjunction in anaphase II of meiosis
when sister chromatids do not seprarate to opposite poles but instead both sister chromatids are pulled toward the same pole together
101
what does sexual reproduction produce
genetically distinct offspring
102
why is recombination an outcome of meiosis
Because the products of meiosis have a different combination of genes then that of the parent cells, allowing the rise of offspring that are genetically distinct from on another and their parents
103
true or false: chromosome replication does not take place in between the two phases of meiosis
true
104
whats a primary oocyte
each of two cells formed when an oogonium undergoes mitosis
105
when does nondisjunction occur
in anaphase I and II of meiosis
106
what is the first polar body and what happens to it
the cell body that receives the smaller poriton of cytoplasm when a primary oocyte undergoes asymmetrical cytokinesis during meiosis I, making it not function which causes it to degenrate soon
107
true or false: mitosis and cytokinesis are different in plant and animal cells
false; the process are very similar
108
what is the dominant generation in vascular plants
the diploid sporophyte
109
what happens to the cell that contains the most cytoplasm after the secondary oocyte undergoes meiosis II
it eventually matures to become an egg
110
define oogenesis
the process of female gamete/egg production in animal
111
howq does budding work
a complete but miniature version of the parent grows out from teh parents body and then seperates to become an independant organism
112
how are homologous chromosomes in each pair position regarding the cells equator in metaphase I of meiosis
one homologous chromosome is positioned on one side of the cell's equator and the other one is positioned on the other side of the equator
113
are the cells produced by mitosis haploid or diploid
diploid
114
what does the cell look like at the end of anaphase
one complete diploid set of chromosomes has been gathered at each pole of the elongated cell
115
what is the main difference between the cells that are created in mitosis vs the cells that are created in meiosis
mitosis results in the creation of daughter cells that are mprecise genetic copies of their parent cells whereas meiosis forms genetically distinct haploid gametes
116
when does meiosis II occur in females
only if the secondary oocyte comes into contact with a sperm cell and fertilization occurs
117
are the orientation of each pair of homologous chromosomes in a cell during meiosis independent or dependent of the other cells and what does this result in
independent to the orientation to other cells which results in some maternal homologues and some paternal homologues facing each pole of the cell resulting in gametes with different combinations of paternal chromosomes
118
whats a spermatogonium
the dploid germ cell from which sperm are produced in the testes
119
what are spermatogonium stimulated to do at the beginning of puberty
to divide by mitosis to form two daughter cells, one of which replenishes the spermatogonia cell population and the other which develops into a primary spermatocyte
120
what do secondary spermatocytes undergo and what does this form
meiosis II to form four spermatids
121
what happens to primary oocytes roughly 3 months after conception
they are arrested in prophase I and remain that way until puberty
122
what is the first phase of mitosis called
prophase
123
are cells that enter meiosis II haploid or diploid
haploid
124
what happens to the cytoplasm in oocytes after meiosis I and what is this called
the cytoplasm is not equally dibvided between the two daughter cells; called asymetrical cytokinesis
125
how many chromatids are in a pair of homologous chromosomes
4
126
whats an oogonium
the diploid germ cell from which eggs are produced in the ovaries
127
where do the copys of chromosomes in each diploid germ cell come from
one copy of the homologous pair is contributed by the female gamete and is of maternal original and the other chromosome is contributed by the male gamete so is of paternal origin
128
what are the two ways that genetic variation is ensured during meiosis
- the creation of gametes that carry different combinations of maternal and paternal chromosomes
- the exchange of genetic material between maternal and paternal chromosomes
129
what do spermatids differentiate into
each differentiates into a sperm cell
130
what is an example of a way that some animals can reproduce asexually
through parthenogenesis
131
are meiosis I and II continuous in females
no
132
what causes cancer
uncontrolled rapid cell divison which results in cells spending less time in interphase and growing very quickly, resulting in a fast-growing mass of non-functional cells (tumour)
133
define asexual reproduction
reproduction that requires only one parent and doesn not involve gametes
134
after the cytoplasm is divided in telophase I of meiosis, how many sets of sister chromatids' do the new cells contain
they contain one set of sister chromatids and is now considered haploid
135
what is reduction division
a form of cell division that produces daughter cells with fewer chromosomes than the parent cells
136
what does asexual reproduction produe
genetically identical offspring
137
true or false: fraternal twins are no more genetically alike than other siblings even though they are twins
true
138
define nondisjunction
failure of homologous chromosome pairs or sister chromatids to separate during meiosis I and II respectively
139
what are 6 advantages to asexual reproduction
- often proceeds more quickly than sexual reproduction
- does not require the presence of a second parent organism
- usually requires less energy then sexual reperoduction
- many forms help maximize the chances that individual offspring survive
- in many forms, the daughter organism does not fully separate from the parent untilit is capable of independant survival
- offers an opppurtunity to make the most of favourable conditions
140
what are spindle fibres
one of a network of fibres made up of mirotubules that form the spindle apparatus during cell division
141
what happens in anaphase of mitosis (3)
- centromere splits apart and the sister chromatids separate from one another
- the spindle fibers that link the centromeres to the poles of the cell shorten, pulling sister chromatids to opposite poles
- as the spindle fibers shorten, other microtubules in the spindle apparatus lengthen and force the poles of the cell away from one another
142
alongside binary fission, what is another way that some bacteria and prokaryotes can also reproduce
conjugation
143
how many genetically unique daughter cells can conjugation create
only one
144
whats a gametophyte
haploid generation of a plant that produces male and female mganetes that fuse at fertilization to form a diploid sporophyte
145
whats parthenogenesis
a form of aseuxal reproduction in which an unfertilized egg develops into an adult
146
what is the dominant generation in no9n vascular plants
the haploid gametophyte
147
what are the two outcomes of meiosis
reduction division and recombination
148
what happens in telophase I of meiosis (2)
- the homologous chromosomes begin to uncoil and the spindle fibres disappear
- the cytoplasm is divided and the nuclear membrane forms around each group of homologous chromosomes to form two cells
149
whats it called when a gamete gains an extra chromosome as a result of nondisjunction
trisomy
150
whats a spore
a reproductive cell capable of devloping into a new organism without fusion with another cell
151
what happens in meiosis II (2)
- goes through similar phases to mitosis
- each cell proceeds through prophase II, metaphase II, anaphase II and telophase II
152
what does nondisjunction produce
gametes that eitehr have too few or too many chromosomes
153
how do spindle fibres lengthen
with the addition of microtubule subunits
154
whats a tetrad
a homologous pair formed during prophase I of meiosis that contains four chromatids
155
what cellular events have to take place to ensure that each daughter cell has the correct genetic information to carry out the functions of mitosis and cytokinesis (4)
- the genetic material of the parent cell must be replicated
- the replicated chromatin must be condensed and organized as chromosomes in the nucleus
- one complete set of chromosomes must be divided into each of two new nuclei
- the cell cytoplasm must divide to produce two complete and functional daughter cells
156
what do oogoniums undergoe and what does this form
mitosis to form two primary oocytes
157
what does spores allow for
the species to reproduce asexually and disperse their offspring long distances
158
what causes fraternal twins
when a second secondary oocyte is released and botgh are fertilized and successfully implanted in the uterues
159
whats a primary spermatocyte
one of two daughter cells formed by the division of the spermatogonia
160
true or false: the first polar body still goes through a second division even though its dysfunctional
false; it may or may not go through a secon divison but in either case the polar bodies will all be dysfunctional
161
in terms of the phases of each process, what is the difference between meiosis and mitosis
they both involve a precise sequence of events with four distinct phases but in meiosis there are two complete round of these phases as opposed to only one round that occurs in mitosis
