Chapter 8 Flashcards
1
Q
double stranded helical nucleic acid,
A
DNA
2
Q
unit of hereditary information consisting of a specific nucleotide sequence
A
gene
3
Q
carrying structure containing DNA and proteins
A
Chromosome
4
Q
the noncondensed form of DNA and proteins present when the cell is not dividing
A
Chromatin
5
Q
Is binary fission an example of sexual or asexual reproduction?
A
Asexual
6
Q
How many chromosomes do bacterial cells have?
A
1
7
Q
A single-celled eukaryote, like an amoeba, would reproduce by ___________.
A
binary fission
8
Q
Are the two cells resulting from binary fission genetically identical or unique?
A
identical
9
Q
Organisms that are the result of sexual reproduction have a pair of chromosomes, one from each parent. A human somatic (body) cell has 46 chromosomes. How many chromosomes are inherited from each parent?
A
23
10
Q
In humans, a sperm cell would have _____ chromosomes
A
23
11
Q
The body cell of a dog has 78 chromosomes. How many chromosomes are in a dog egg cell?
A
39
12
Q
T/F The number of chromosomes correlates to the complexity of the organism. For example, a complex organism like a human will always have more chromosomes than a ‘lower’ organism like a tree.
A
FALSE
13
Q
How many chromosomes are found in a human zygote?
A
46
14
Q
In humans, a cell from the liver would have _____ chromosomes.
A
46
15
Q
Most organelles duplicate during the ___ phase in order to prepare for becoming two separate cells, both of which will need a set of organelles.
A
G1 phase
16
Q
How many chromosomes are present during the G1 phase in humans?
A
46
17
Q
Which two organelles duplicate themselves independently and separately from the rest of the cell cycle?
A
mitochondria and chloroplast
18
Q
How many chromatids are present during the S phase in humans?
A
92
19
Q
Based on the illustration of the cell cycle, the cell spends most of its time in which phase?
A
interphase
20
Q
If the chromosomes were to not line up in metaphase, would each new daughter cell have the correct number of chromosomes?
A
no
21
Q
What would happen if the spindles did not attach to each chromosome?
A
the chromatids may fail to separate
22
Q
Choose the purposes of mitosis:
Growth
Gamete formation
cell replacement
asexual reproduction
A
Growth, asexual reproduction, cell replacement
23
Q
Which of the following types of animal cells would you expect to have a fast (frequent) rate of mitosis?
A
skin
24
Q
A fish embryo would have a _____ rate of cell division.
A
fast
25
Which of the following disappear during telophase?
Nuclear envelope
Mitotic spindle
Nucleolus
mitotic spindle
26
The imaginary line where the chromosomes line up in the center of the cell is called the _______________.
Mitosis plate
metaphase plate
middle plate
mitochondria plate
Metaphase plante
27
Which of the following reform during telophase?
nuclear envelope
mitotic spindle
Centrosomes
Nuclear envelope
28
Which of the following has disapeared by the end of prometaphase?
mitotic spindle
sister chromatids
centromere
nuclear envelope
centrosome
Nuclear envelope
29
Cytokinesis overlaps with which two phases of the cell cycle?
Anaphase and telophase
30
Are daughter cells resulting from mitosis genetically unique or identical?
Identical
31
In humans, how many chromosomes are in each daughter cell following mitosis?
46
32
Which phase of the cell cycle is the longest?
interphase
33
How would mutations on a gene controlling the G2 checkpoint contribute to the formation of a cancer?
It would allow cells with inaccurate DNA replication to divide.
34
If there is abnormal growth of cells that never leaves the original tissue and has well-definied edges, it is classified as a ____________________ tumor.
benign
35
You look into a microscope and see cells that growing together so each cell is touching another cell or surface. You then notice that the cells are continuing to grow on top of eachother. You would conclude that this may be a mutation in the genes that signal for (control of):
contact inhibition
36
If the cells of a tumor break off and travel to a different part of the body and begin a tumor in the new location the cancer is said to
have metastisized
37
A cell has a diploid (2n) number of 4. How many chromosomes will be present in each of the resulting haploid (n) cells?
2
38
If a wombat has 40 chromosomes, how many chromosomes must be in each egg/sperm to ensure that the offspring will have the correct number of chromosomes?
20
39
In humans, which sex chromosomes would genetically denote a female?
XX
40
Homologous chromosomes are _______ to each other.
Similar
41
T/F? Even though they carry different genes, sex chromosomes behave as a __________________.
homologous pair
42
In which phase is DNA duplicated?
S Phase of Interphase
43
Sister chromatids align at the center of the cell.
Metaphase II
44
Tetrads separate, resulting in haploid cells
Anaphase I
45
Sister chromatids separate
Anaphase II
46
Tetrads align along the equator of the cell
Metaphase I
47
Occurs in body cells, such as skin, liver, and bone
Mitosis
48
Crossing over
Prophase I
49
4 separate cells form that are genetically unique
Telophase II/Cytokinesis
50
DNA duplicates
Interphase
51
Occurs in the ovaries and testes of animals
Meiosis
52
During which phase of meiosis are the sister chromatids separated?
Anaphase II
53
During which phase of meiosis are the homologous chromosome pairs separated?
Anaphase I
54
In humans, how many chromosomes does each daughter cell have after MEIOSIS II?
23
55
In humans, how many chromosomes does each daughter cell have after MEIOSIS I?
23
56
In humans, how many chromosomes does each daughter cell have after MITOSIS?
46
57
Which of the following contribute to genetic variation?
crossing over
independent orientation
mutation
mitosis
binary fission
random fertilization
Crossing over, independent orientation, random fertilization, mutation
58
Match:
XXX
Trisomy 21
XO
XXY
-------------
Down's syndrome
"Metafemale"
Turner's syndrome
Klinefelter's syndrome
XXX: Metafemale
Trisomy 21: Downs
XO: Turners
XXY: Klinefelters
59
Which of the following disorders involve autosomes?
Down's syndrome
60
Which of the following would be easiest to view under a microscope?
chromosomes
61
Where do the microtubules of the spindle originate during mitosis in both plant and animal cells?
In the centrosomes.
62
Organisms produced as a result of binary fission exhibit ______ genetic variation.
no
63
During which phase(s) of mitosis do we find chromosomes composed of two chromatids (duplicated chromosome)?
from G2 of interphase through metaphase
64
All of the following occur during mitosis except:
the formation of a spindle.
the condensing of chromosomes.
the disappearance of the nucleolus.
the uncoupling of chromatids at the centromere.
the synthesis of DNA.
Synthesis of dna
65
Which of the following does not occur during mitosis?
packaging of the chromosomes
replication of the DNA
spindle formation
separation of the centrosomes
separation of sister chromatids
Replication of DNA
66
The genetic material is duplicated during
S phase
67
The haploid (n) number of chromosomes is found in nearly ______ cells of humans and most other animals.
sex cells
68
The genetic material is duplicated during
the mitotic phase.
mitosis.
G2
G1
the S phase.
The S Phase
69
Organisms produced as a result of binary fission exhibit ______ genetic variation
no
70
A microtubule organizing center (__________) is located at _________ of the dividing cell in both plants and animals.
centrosome
each pole
71
Viruses and chemical exposure can cause mutations in ___________ which can lead to cancer.
proto-oncogenes
72
In some organisms, mitosis occurs without cytokinesis occurring. This will result in what?
A cell having more than one nucleus.
73
Which of the following organisms does not use mitosis to make another cell?
mushroom
banana tree
bacterium
cow
cockroach
Bacteria
74
How do the daughter cells at the end of mitosis compare with their parent cell when it was in G1 of the cell cycle?
The daughter cells have the same number of chromosomes and the same amount of DNA.
75
One difference between a cancer cell and a normal cell is that:
Cancer cells continue to divide even beyond their boundaries.
76
During which phase(s) of mitosis do we find chromosomes composed of two chromatids (duplicated chromosome)?
from G2 of interphase through metaphase
77
T/F? Binary fission uses a spindle (network of microtubules made by centrosomes) for the separation of daughter chromosomes, just as in mitosis.
FALSE
78
DNA replication occurs in the ____ stage of interphase just before _______.
last; mitosis
79
Contact inhibition stops normal cells from dividing when they ___________, but this is not functional in cancer cells.
come in contact with neighboring cells
80
DNA replication occurs in the _____ stage of ________ just before mitosis.
last stage of interphase
81
A ____________ ___________ ___________(centrosome) is located at each pole of the dividing cell in both _______ and _______
microtubule organizing center
both plants and animals.
82
How many individuals are required in asexual reproduction?
1 individual
83
Cell division in eukaryotes involves separate processes called __________ and __________
mitosis and cytokinesis
84
The centromere is a region in which:
chromatids of a duplicated chromosome are attached to one another and where the DNA is pinched in a bit.
85
Where do the microtubules of the spindle originate during mitosis in both plant and animal cells?
Centrosomere
86
T/F The haploid (n) number of chromosomes is found in nearly all body cells of humans and most other animals
FALSE
87
Chromosomes are aligned along the cell's equator during ___.
The metaphase
88
T/F Binary fission uses a spindle (network of microtubules made by centrosomes) for the separation of daughter chromosomes, just as in mitosis.
FALSE
89
Brain cells (neurons) are constantly in _____ phase of interphase. This means that they _______ able to regenerate after injury.
G0
are not able to regenerate
90
A particular cell has not replicated its DNA yet. The cell in question is most likely in
G1
91
_______________ stops normal cells from dividing when they come in contact with neighboring cells, but this is not functional in ______ cells
Contact inhibition, cancer cells
92
In anaphase II of meiosis the ________ are split, breaking the _________.
chromatids
Centromere
93
T/FSources of genetic variation in a sexually reproduction arises only from fertilization.
FALSE
94
Another name for a tetrad is a ______.
bivalent
95
Spindle fibers connect to the ______ fibers meiosis.
Kinetochore
96
Crossing over occurs during ____________
Prophase I.
97
t/f Meiosis leads to gametogenesis, oogenesis, and spermatogenesis.
TRUE
98
T/F? The centromere holds the homologous chromosomes together in meiosis II.
FALSE, the centromere is broken
99
T/F DNA is replicated between meiosis I and meiosis II.
FALSE, S phase of Interphase
100
The chromosome ______ are located at the metaphase plate during metaphase I.
tetrads
101
A failure of meiosis can lead to ____ number of genes in a gamete and therefore inviable gametes.
Increased
102
T/F the centromere holds the ______________ together in meiosis II.
sister chromatids
103
T/F The events of meiosis II are most similar to interphase.
FALSE
104
Each gamete contains _____ sex chromosome(s)
1
105
In meiosis, chromosomes are aligned in the center of the cell by ___________
spindle fibers.
106
Alignment of the chromosomes during metaphase I leads to _____________________
variation of genetic material.
107
T/F? At the end of meiosis II, the chromosomes consist of sister chromatids held together at a centromere.
FALSE
108
The microtubule spindle apparatus originates from the _________
centrosomes
109
There is/are ______ division(s) in meiosis.
2
110
_______ are arranged along the equator during metaphase I
Tetrads
111
T/F? Meiosis leads to gametogenesis, oogenesis, and spermatogenesis.
TRUE
112
The replication of DNA and the duplication of genes occurs during _______
S phase of Interphase
113
In meiosis the daughter cells are genetically ___.
Different
114
T/F? The microtubule spindle apparatus originates from the plasma membrane.
FALSE
115
In anaphase II of meiosis the ___________ are split, breaking the ____________
chromatids, centromere
116
During anaphase I the association between members of a tetrad is _______and they ________.
disrupted, seperate
117
The cell formed through fertilization is called a _______.
zygote
118
T/F Homologous chromosomes are similar in size, similar in shape and location of the centromere, and carry the genetic code for the same traits.
TRUE
119
Homologue separation occurs during ________of meiosis.
anaphase I
120
The ___________ holds the sister chromatids together in meiosis I.
centromere
121
If DNA replication has already occurred, the chromosomes consist of ____________ held together at a centromere.
sister chromatids
122
If there is any damage to the DNA the cell will try to repair the damage before allowing the cell to continue to the _______ of the cell cycle
S phase
123
If a sperm contains 4 chromosomes, it comes from an animal that has __ chromosomes
8
124
If DNA replication has already occurred, the chromosomes consist of sister chromatids held together at a __________.
centromere
125
Does asexual reproduction create genetically identical or adverse offspring?
Identical
126
Does sexual reproduction create genetically identical or adverse offspring?
Diverse
127
When is asexual reproduction beneficial?
You don't need a mate, it takes less time and energy.
128
How is asexual reproduction bad?
More competition for resources and stable environment and no genetic diversity.
129
What are three benefits of sexual reproduction?
Having genetic diversity, having genes to adapt, evolution occurs easier.
130
What are some organisms that do asexual reproduction?
Bacteria, yeast, liver cells, starfish.
131
What are chromosomes?
Condensed DNA when cell is dividing.
132
What is chromatin?
Loose DNA when cell is not dividing.
133
What is a gene?
A unit of heredity found on a certain place on a chromosome that codes for a certain product.
134
What is DNA?
Your genetic blueprint.
135
What are chromosomes, chromatin, and genes made of?
DNA and proteins.
136
Where may they be found in the cell?
Nucleolus.
137
How many chromosomes are found in a human body cell? How many strands of chromosomes?
46 chromosomes, 92 strands.
138
How many genes can be found in a human cell?
Thousands
139
What isthe information in genes used for?
Making proteins and enzymes, growth and development of a cell, protecting the organism from infection, and ensuring fidelity of offspring to the parent.
140
Where do diploid cells come from?
2 haploid cells
141
What are somatic cells?
Body cells
142
Are somatic cells haploid or diploid?
Diploid
143
What is the notation for diploid?
2n
144
What are gametes?
Sex cells
145
Are gametes haploid or diploid?
Haploid
146
What is the notation for haploid?
1n
147
What does n stand for?
Number of chromosomes
148
What process do bacteria divide by?
Binary fission
149
How does binary fission work?
DNA replicates and a cell membrane forms between the 2 chromosomes, dividing them and forming 2 daughter cells.
150
In binary fission, are the 2 daughter cells genetically identical or diverse?
Identical
151
How many chromosomes do bacteria cells have?
1
152
Does the number of chromosomes correlate to the complexity of the organism?
No
153
Why are somatic cells diploid cells?
Because they have one set of chromosomes donated by each parent, resulting in TWO sets of chromosomes.
154
How is a zygote formed?
When two gametes combine through fertilization
155
What is the name for gametes found in males?
Sperm
156
What is the name for gametes found in females?
Egg/Ovaries
157
In humans, how many chromosomes are inherited from the mother? The father?
23 each
158
In humans, how many chromosomes are found in a gamete?
23 chromosomes.
159
After fertilization, will the resulting zygote be haploid or diploid?
Diploid
160
How many chromosomes are found in a human zygote?
46
161
The diploid number for a horse is 64. What is the haploid number?
32
162
How many chromosomes are in a horse gamete?
32
163
How many chromosomes are in a horse zygote?
64
164
What is the cell cycle?
A sequence of growth + division of a cell.
165
What does the cell cycle begin and end with?
1 parent cell, 2 daughter cells.
166
Is this an example of asexual or sexual reproduction?
Asexual
167
What are the three main stages of the eukaryotic cell cycle?
Interphase, Mitosis, Cytokinesis
168
Define interphase.
G1, G2, and S phase. Where DNA is replicated before mitosis. The cell contents are duplicated here.
169
Define Mitosis
separating of sister chromatids. Genetically identical daughter cells. Division of nucleus through PMAT.
170
Define Cytokinesis.
When the cytoplasm is dividing. Not part of mitosis.
171
What are the 4 sub-phases for interphase?
G0, G1, G2, and S phase.
172
Summarize G0 phase.
Normal cell functions, not dividing.
173
Summarize G1 phase.
Growth. Duplicating organelles + making proteins for mitosis.
174
Summarize S phase.
Synthesis phase. DNA replication. One set for each daughter cell.
175
Summarize G2 phase.
Growth. Replicating centrosomes.
176
What are centrosomes made up of?
2 centrioles.
177
When a cell is dividing, how many centrosomes and centrioles are present?
2 centrosomes and 4 centrioles.
178
Which 2 organells duplucate autonomously and separately from the rest of the cell cycle?
Mitochondria and Chloroplast
179
Why does the cell begin to make large amounts of proteins?
To fuel mitosis.
180
How many strands of DNA are present during the G1 phase in humans?
1 strand.
181
Are these cells n or 2n?
2n
182
How many strands of DNA are present during the S phase in humans?
1 strand, duplicated.
183
How many strands of DNA are present during the G2 phase in humans?
2 strands
184
What is a centromere?
Holds together 2 sister chromatids
185
What are sister chromatids?
Identical copies of each other produced during DNA replication
186
What is the purpose of checkpoints in the cell cycle?
To make sure the cell is okay to go onto the next phase.
187
What is the G1 checkpoint?
It cheks to make sure the cell has room to grow, and it checks for DNA damage.
188
The G1 checkpoint happens prior to what phase?
The S phase
189
Why must nutrients be available before more cells can be made?
Because the nutrients are needed for mitosis.
190
What is the G2 checkpoint?
It assesses DNA errors.
191
The G2 checkpoint happens prior to wha phase?
Mitotic phase.
192
How would a replication error in DNA affect the function of the new daughter cell?
The cell could be mutated and continue to produce the mutation, or the cell will program itself to die.
193
What is another word for the cell programing itself to die?
Apoptosis
194
What is the M checkpoint?
It checks for the spindle fivers attatched to the kinetochore.
195
The M checkpoint is prior to which phase?
Anaphase
196
If the cell fails these checkpoints after it has committed to divide, what will typically happen to the cell?
It will destroy itself.
197
Why would the cell go through such drastic measures to make sure mitosis occurs without error?
To make sure the daughter cells have the correct number of chromosomes.
198
What would happen if the cell did not divide properly and continued to pass the checkpoints, even when it should not pass?
The cells produced will have either 1 extra or 1 less chromosome, and they will be mutated.
199
What are growth factors?
Proteins that signal and communicate between the cells. They are needed to stimulate cell division.
200
What is Density Dependent?
Contact between cells inhibits further mitosis.
201
What is another name for density dependent?
Contact inhibition
202
Why would cells stop mitosing when they fill up a space?
Because the density is at full capacity, and there is no room to divide.
203
What term describes "cells must have an underlying surface on which to adhere in order to grow?"
Anchorage Dependent
204
What is mitosis?
Phase of the cell cycle where the nucleus divides.
205
What type of cellular reproduction is this?
Asexual
206
What are examples of cells that do NOT go through mitosis?
Sex cells, haploid cells, RBC, nerve cells, heart cells.
207
What are the 3 main functions of mitosis?
1) Growth + Development
2) Replacement of Cells
3) Asexual reproduction
208
What types of animal body cells have a fast rate of mitosis?
Skin cells
209
Does mitosis occur in somatic cells or gametes?
Somatic cells
210
What is the first stage of mitosis?
Prophase
211
What happens to DNA during prophase?
Chromatin form condenses into chromosomes.
212
What change has occured to the nuclear envelope? To the centrosomes?
The nuclear envelope and nucleolus start to disappear. The centrosomes start tp move to either pole of the cell.
213
What protein fivers attatch to the kinetochore proteins at the centromere of the chromosomes?
Spindle fibers
214
How many chromosomes are there in prophase? Sister chromatids?
46 chromosomes, 92 chromatids.
215
What is the second phase of mitosis?
Metaphase
216
What happens during metaphase?
The sister chromatids line up on the center of the cell.
217
What is the imaginary line called where the chromosomes line up in the center of the cell?
Metaphase plate.
218
What is guiding the chromosomes to the center?
Microtubules (spindle fibers)
219
Which phase is a checkpoint?
Metaphase.
220
What would happen if the chromosomes were not lined up in metaphase? Would each new daughter cell have the correct number of chromosomes?
Cell may give time to correct, or mitosis continues with wrong numbers of chromosomes in each sell.
No.
221
How many chromosomes are there in metaphase? Sister Chromatids?
46 Chromosomes, 92 Chromatids
222
What is the third phase of mitosis?
Anaphase
223
What happens during anaphase?
The chromatids are separated and pulled to either pole of the cell.
224
What happens to the duplicated chromosomes? The sister chromatids?
The centromeres come apart and the chromatids are separated. They are now called chromosomes.
225
What protein 'fibers' pull the chromosomes?
spindle fibers.
226
How many chromosomes are there in anaphase? Sister chromatids?
92 chromosomes, 0 chromatids.
227
How many chromosomes are on either pole in anaphase?
46 on either pole
228
What is the last stage of mitosis called?
Telophase
229
What happens during telophase?
The cell starts to pinch off. The form of the nucleus starts to come back.
230
What is a notable characteristic of telophase?
Clevage furrow.
231
What is a clevage furrow?
Where daughter cells are pinching off.
232
What happens to chromosomes in telophase?
They uncondense back into chromatin.
233
What change occurs to the nuclear envelope in telophase?
The appearance of it reforms.
234
How many chromosomes are there in telophase?
92 (46 on either end)
235
What is Cytokenisis?
The division of the cytoplasm into two daughter cells.
236
Which 2 phases of mitosis does cytokenisis overlap with?
Anaphase and telophase.
237
How many chromosomes are there in cytokenisis?
46 (in each daughter cell)
238
Which phase of the cell cycle is the longest?
Interphase.
239
Are the new cells from mitosis haploid or diploid?
Diploid
240
Are the daughter cells genetically identical or diverse
Identical because everything was copied and distributed evenly.
241
What are cancer cells the result of?
Multiple DNA mutations
242
How would mutations on cell checkpoint genes contribute to cancer?
Because cancer replicates without limit, so it ignores checkpoints.
243
What is a tumor?
An abromal mass.
244
What is a benign tumor?
One that doesn't spread.
245
What is a malignant tumor?
One that spreads uncontrollably.
246
What is metastasis?
Spread of cancer cells.
247
What does it mean when a tumor has metastasized?
It has started to spread.
248
How do more aggressive cancers differ in terms of rate of mitosis?
They can break off and duplicate quickly in other places.
249
Does chemotherapy target cells with a slow or fast rate of mitosis?
Fast rate.
250
What is radiation and chemotherapy?
Radiation destroys cancer cells, and chemo is a drug that treats metastatic tumors. They disrupt the cell cycle.
251
What is meiosis?
Reduction division producing 4 haploid cells. Produces gametes
252
How many cell divisions occur in meiosis?
2
253
How many cell divisions occur in mitosis?
1
254
How many daughter cells are produced in mitosis?
2
255
Are daughter cells in mitosis haploid or diploid?
Diploid.
256
Cells in mitosis are _______
identical
257
How many gametes are produced from one parent cell in meiosis?
4
258
Are cells in meiosis haploid or diploid?
Haploid
259
Are cells in meiosis unique or identical?
Unique
260
Which cells do mitosis and meiosis occur?
Mitosis in somatic cells, meiosis in egg/testes.
261
How many pairs of chromosomes do diploid cells have?
23 pairs.
262
What are autosomal chromosomes?
Pairs of chromosomes that are common to men and women.
263
Which pair of chromosomes is different?
Sex chromosomes.
264
Which sex chromosomes do women have? Men?
XX, XY
265
What are homologous chromosomes?
Chromosomes in a matched pair. They can be copies or duplications. Each pair of chromosomes represents homologous chromosomes.
266
Are homologous chromosomes identical to each other?
No, but they are similar.
267
Are sex chromosomes always identical? Are they considered homologous?
They are not always identical, and they are considered homologous.
268
Why do gametes must only have one set of chromosomes?
Because when they fertilize, the zygote has a set from each parent to make all 46.
269
Hedgehogs have a diploid number of 90. How many chromosomes does a hedgehog zygote have?
90
270
In which phase is DNA duplicated?
In S phase of Interphase
271
Is there an interphase before meiosis I?
Yes
272
What happens in prophase I?
Replicated chromosomes condense, homologous pairs match up, crossing over occurs between homologous pairs, spindle forms, nuclear envelope disappears.
273
What are tetrads?
4 chromatids
274
What is the term used to describe what happens when homologous chromosomes pair up to form tetrads?
Synapsis
275
What is crossing over?
When homologous chromosomes exchange DNA segments, reuslting in non-identical chromatids.
276
What is the purpose of crossing over?
To create varation.
277
Why might crossing over be advantageous to the offspring?
Because it creates genetic variation
278
In prophase 1, how many duplicated chromosomes are present?
46 duplicated chromosomes
279
How many sister chromatids are present in prophase 1?
92
280
What happens in metaphase 1?
Paired homologous chromosomes (tetrads) align at the center of the cell.
281
How is the arrangement of chromosomes in metaphase 1 different from that of metaphase?
In metaphase 1, the tetrads are lined up, in metaphase, the sister chromatids are lined up.
282
In metaphase 1, how many duplicated chromosomes are present? Sister chromatids?
46, 92
283
What happens in anaphase 1?
Tetrads are split up and homologous pairs are pulled to either side of the cell.
284
Do centromeres separate in anaphase 1?
No, the centromeres and chromatids do not separate yet.
285
In anaphase 1, how many duplicated chromosomes are present? How many sister chromatids?
23 pairs on each side, 46 chromatids on either side.
286
What happens in telophase 1?
The number of chromosomes is now reduced by half. After this phase the cell is considered to be haploid.( only one set of chromosomes) Note however, that the chromosomes are still replicated, and the sister chromatids must still be separated during meiosis II.
287
In telophase 1, how many duplicated chromosomes are present? Sister chromatids?
23 chromosomes, 46 sister chromatids.
288
What happens in cytokenisis?
The cytoplasm and cell divide, resulting in haploid cells.
289
Are the chromosomes in cytokenisis duplicated or unduplicated?
Duplicated
290
Are tetrads present in cytokinesis
No.
291
Is there an interphase for meiosis II?
No
292
Why does meiosis II occur?
Because there is too much DNA in the haploid daughter cells
293
In prophase 2, how many duplicated chromosomes are present? Sister chromatids?
23, 46
294
How is prophase II different from prophase I?
Prophase II involves separation of sister chromatids, while prophase I involves the separation of homologous chromosomes.
295
How is the arrangement of chromosomes in metaphase II different than in metaphase I?
The chromosomes are no longer in tetrads
296
How is the arrangement of chromosomes in metaphase II different than in metaphase of mitosis?
The sister chromatids in metaphase II are crossed over.
297
In metaphase II, how many duplicated chromosomes are present? Sister chromatids?
23, 46
298
What happens in anaphase II?
The sister chromatids are finally separated.
299
How many duplicated chromosomes are present in anaphase II? Chromatids?
46 (23 either side), 0
300
How many haploid cells do the cells in telophase II divide into?
4
301
How many duplicated chromosomes are present in telophase II?
23 on each side
302
In the second cytokenisis of meiosis, how many chromosomes will be present in each resulting cell?
23
303
Are the resulting cells haploid or diploid?
Haploid
304
Are the chromosomes duplucated or unduplicated at the end of the second cytokenisis in meiosis?
Unduplicated
305
During which phase of meiosis are the homologous chromosomes separated?
Anaphase I
306
During which phase of meiosis are the sister chromatids separated?
Anaphase II
307
In a human cell, how many chromosomes does each daughter cell have after meiosis I?
23
308
In a human cell, how many chromosomes does each daughter cell have after meiosis II?
23
309
Describe why a person's siblings are genetically different from one another?
Because of crossing over in prophase I.
310
What are three purposes of meiosis?
To replace diploid cells with haploid cells, to make gametes, and to create genetic variation.
311
What are other sources of genetic variation?
Mutation, independent assortment
312
What is nondisjunction?
When a pair of homologous chromosomes or sister chromatids fails to separate evenly during meiosis.
313
Can nondisjunction occur in meiosis I and II?
Yes
314
If nondisjunction occurs in meiosis I, how many gametes with abnormal chromosomes would result?
4 abnormal. (2 n+1, 2 n-1)
315
If nondisjunction occurs in meiosis II, how many gametes with abnormal chromosomes would result?
2 abnormal
316
What is monosomy?
When a cell is missing a copy.
317
What is trisomy?
When a cell has an extra copy
318
What is a karyotype?
A magnified image of chromosomes taken in homologous pairsand put in order.
319
Which phase is used for karyotyping and why?
Metaphase because it is the most clearly visualized.
320
What is aneuploidy?
Identifying an abnormal number of chromosomes.
321
What is Trisomy 21?
Down Syndrome. Extra chromosome 21, so a total of 47 chromosomes. Symptoms are lower cognition and facial differences.
322
What is Klinefelter syndrome?
When male has extra X chromosome. XXY. More feminine, more breast tissue, smaller testicles, and often sterile.
323
What is Turner Syndrome?
Females missing an X chromosome. XO. 45 chromosomes total. Webbed neck, heart problems, short stacked.
324
What are Metafemales?
When females have an extra X chromosome. XXX. Appear normal, might have low muscle deficiency and learning disabilities.
325
What is Jacobs Syndrome?
Supermale. Males have an extra Y chromosome. XYY. They are taller and more aggressive.
326
Explain how sexual reproduction can result in genetic diversity.
Because the zygote has half the genetic material from each parent
327
Explain the two main roles cell division plays in continuing life.
Growth and repair, and replacement of old cells.
328
Describe the process of binary fission.
Binary fission is the process bacteria use to replicate themselves. DNA replicates and cell membrane forms between the two chromosomes, dividing them and forming 2 daughter cells.
329
What factors in eukaryotic cells make cell division more complex than in prokaryotic cells?
The structure of the nuclear envelope in eukaryotic cells is more advanced.
330
Distinguish the difference between chromosomes, genes, and DNA.
Chromosomes carry DNA (condensed), genes are segments of DNA that give you physical characteristics, and DNA is your genetic blueprint.
331
How do sister chromatids attach to one another?
With a centromere
332
When in cell division, how do sister chromatids separate?
In anaphase, they are pulled to either end of the cell by spindle fibers.
333
Is the DNA in sister chromatids always identical?
Yes
334
Describe the phases and steps of the cell cycle leading to mitosis.
Before mitosis is the interphase, where DNA and organelles are duplicated and checkpoints are gone through to make sure the cell has the okay to carry out mitosis.
335
What must happen before cells can divide?
They must pass the checkpoints.
336
Describe cytokenisis.
Cytokinesis is when the cytoplasm separates in the 2 cells. Results in 2 diploid cells for mitosis, and 4 haploid cells in meiosis.
337
Define three main purposes for mitosis.
To grow and repair, replace old cells, and asexual reproduction.
338
Understand the stages of mitosis and what occurs at each phase.
Prophase: nuclear envelope disappearing, chromatin condensing into chromosomes, centrosomes moving to either end, spindle fiber formation.
Metaphase: sister chromatids move to center of cell on metaphase plate
Anaphase: centromeres broken, chromosomes move to either end of the cell.
Telophase: Clevage furrow emerges. Nuclear envelope reforming
339
Describe checkpoints. Where in the cell cycle do they occur?
Checkpoints are points within the cell cycle where the cell is checked to make sure it can undergo mitosis. G1 checkpoint happens before the S phase, G2 checkpoint happens before the mitotic phase, and M checkpoint happens before anaphase.
340
What role does mitosis play in cancer?
Cancer cells uncontrollably reproduce.
341
Describe homologous chromosome.
Homologous chromosomes are chromosome pairs. You get one from each parent, and they are similar but not identical.
342
Describe duplicated chromosome.
Duplicated chromosomes are when a single chromosome is duplicated and joined at the centromere. (identical)
343
Describe chromatid.
Chromatid is two identical chromosomes that split and contain the same genetic material.
344
Describe centromere
What holds together chromatids.
345
Describe tetrad
A paired set of homologous chromosomes, each containing 2 sister chromatids. (4 total)
346
Define the difference between autosome and sex chromosome.
Autosomal are chromosomes that are found in both men and women, and sex chromosomes are what determines the sex of offspring. (XX or XY).
347
Define diploid.
Diploid is a cell or organism that has paired chromosomes, one from each parent.
348
Define haploid.
When a cell has only one set of chromosomes.
349
Identify cells in humans that are haploid and diploid.
Diploid - somatic (body) cells. Haploid - gametes (sex cells)
350
Explain how mitosis and meiosis are different.
Mitosis produces genetically identical cells, whereas meiosis produces genetically diverse cells.
351
How many daughter cells does meiosis produce? Are they genetically identical?
Meiosis makes 4, and they are not identical.
352
Discuss events occuring during interphase of meiosis.
It is when there are checkpoints and DNA replication. Preparing the cell to divide.
353
Explain prophase I (synapsis, crossing over, formation of tetrads).
Prophase I is where homologous chromosomes pair up, tetrads form, crossing over (sharing DNA segments) happens.
354
Explain metaphase I
metaphase I is where tetrads line up on the center.
355
Explain anaphase I
When the tetrads are split and pulled to either end of the cell.
356
Explain telophase I
Chromosomes now reduced by half. Cell is now considered to be haploid. However, chromosomes are still replicated and sister chromatids need to be separated.
357
Explain prophase II
Each cell is haploid with chromosomes in replicated form
358
Explain metaphase II
Sister chromatids align in the center.
359
Explain anaphase II
Sister chromatids separated and pulled to either side
360
Explain telophase II
4 haploid cells starting to form, each with 23 chromosomes.
361
Cytokenisis II will result in how many daughter cells?
4 daughter cells.
362
Discuss the importance of crossing over.
It creates genetic variability in offspring.
363
Define nondisjunction.
Nondisjunction is an error of meiosis when a pair of homologous chromosomes or sister chromatids fails to separate evenly.
364
List some disorders that result from nondisjunction of chromosomes.
Trisomy 21, Jacob's, Kleinfelter, Metafemale, Turner Syndrome
365
Discuss the major sources of genetic variation.
Mutation, crossing over, independent assortment.
366
If an organism has 16 total chromosomes (diploid), state the haploid number, number of chromosome pairs, and number of chromosomes found in the zygote.
Haploid - 8
Pairs - 8 pairs
Zygote - 16 chromosomes
367
Discuss the sources of genetic variation that occur in meiosis. Describe crossing over, orientation, mutation, and fertilization in your own words.
Independent assortment: where homologous chromosomes are randomly distributed to separate poles during meiosis.
Crossing over: when homologous chromosomes pair up and exchange DNA segments.
368
Dscribe the different chromosome abnormalities, including the chromosome types and symptoms.
Trisomy 21: extra chromosome on 21. Slow cognition, facial differences.
Kelinfelters: XXY. Males are more feminine, more breast tissue, small testicles, sterile.
Jacob's: XYY. Males have extra Y. Taller, more aggressive.
Metafemale: XXX. Female has extra X. Low muscle deficiency, learning disability.
Turner: XO. Females missing and X. Webbed neck, short stature, heart problems. THE ONLY MONOSOMY (45 chromosomes)
