Chapter 10 - PowerPoint Flashcards
(149 cards)
1
Q
What are the two types of nuclear division?
A
mitosis and meiosis
2
Q
In mitosis are the daughter cells exact genetic copies of the parent cells?
A
yes
3
Q
What are ploidy human cells?
A
diploid
4
Q
What does diploid mean?
A
2 copies of each chromosomes, 2n
5
Q
In meiosis how many divisions are there?
A
2
6
Q
How many daughter cells are produced in meiosis?
A
4
7
Q
What are the daughter cells of meiosis called?
A
gametes
8
Q
What is haploid mean?
A
one copy, n
9
Q
What is the master program of molecular checks and balences?
A
In mitosis, DNA is replicated and split evenly
10
Q
What is the mitotic cytoskeleton do?
A
separates replicated DNA molecules precisely into the daughter cells
11
Q
What are chromosomes made of?
A
DNA and proteins
12
Q
What do proteins do in DNA?
A
stabilize, assist in packaging DNA during cell division, and influence the expression of individual genes
13
Q
What shape are chromosomes in eukaryotes?
A
linear
14
Q
What does histone proteins do?
A
compact DNA
15
Q
What is chromatin?
A
DNA and all of its associated protiens
16
Q
What is a nucleosome?
A
8-protein nucleosome core particle forms when DNA winds around the histones H2A, H2B, H3, and H4
17
Q
What connects nucleosomes?
A
shorter liner segment of DNA
18
Q
What are the histone proteins?
A
H2A, H2B, H3, and H4
19
Q
How many of each histone proteins are in a nucleosome?
A
2
20
Q
What is the first step of compaction
A
formation of nucleosomes
21
Q
What charges does DNA have? why?
A
negative bc of phosphate groups
22
Q
How wide is a nucleosomes?
A
10nm
23
Q
How are nucleosomes further compacted? how big is it?
A
nucleosome and linker are bound by the fifth histone protein H1
30 nm
24
Q
What is the difference between chromosomes and chromatin?
A
chromosomes are final form, everything else before this with proteins is chromatin
25
What does the solenoid model predict?
nucleosomes spiral helically
| with about six nucleosomes per turn
26
Which chromatin is packed loosley?
euchromatin
27
Which chromatin is packed densly?
heterochromatin
28
Is euchromatin or heterochromatin regions more highly expressed?
euchromatin
29
What are Sister Chromatids
2 copies of the chromosome within the replicated chromosome
30
What are the sister chromatids held together by? where?
sister chromatid cohesion, at the center
31
What is cohesion
protein complex
32
Are homologous chromosomes identical?
nope
33
Are sister chromatids identical?
yes
34
What is ploidy?
The number of chromosome sets in a cell or species
35
What is a Karyotype?
Individual’s particular array of chromosomes.
36
How to prepare cells for a karyotypes?
1. Add sample to culture medium that has stimulator for growth and division of cells (white blood cells in the case of blood). Incubate at 37oC.
2. Stain the cells so that the chromosomes are distinguished.
3. View the stained cells under a microscope equipped with a digital imaging
system and take a digital photograph.
37
What are the steps included in eukaryotic cell cycle?
G1, S, G2, M, C
38
What is the longest phase?
G1
39
What steps are in interphase?
G1, S, G2
40
What is G1?
Gap 1 Phase, where primary growth takes places, is the longest phase
41
Which is phase varies in length?
G1
42
What is a cell that stays in the G0 phase?
neuron
43
How long does it take for a cell to divide?
24 hrs
44
how long does the G1 phase take?
10 hrs
45
How long does the S phase take?
9 hrs
46
How long does the G2 phase take?
4 hrs
47
How long does the M phase take?
1 hr
48
What happens in the S (synthesis) phase?
replication of DNA
49
What happens in the G2 phase?
organelles replicate, microtubules organize
50
What are the 5 phases of mitosis?
prophase, prometaphase, metaphase, anaphase, telophase
51
What happens in cytokinesis?
separation of 2 new cells
52
Are human sex cells haploid or diploid?
haploid
53
What happens to the centrioles during mitosis?
they duplicate and divide
54
What is the main microtubule organizing center (MTOC)?
centrosome
55
Where do microtubules extend from?
centrosomes
56
What are asters?
starlike arrays formed from microtubules extending from the centersome
57
What happens to the nuclear envelope during interphase?
breaks down
58
In mitosis, at what stage do chromosomes first become visible with a light microscope?
prophase
59
Do asters exist in both plants and animal?
no, just animals
60
What are the 3 main things that occur in prophase?
1) spindle apparatus assembles (2 centersomes move to opposite poles forming spindle apparatus, and the formation of asters in animals)
2) nuclear envelope starts to disintegrate
3) nucleolus disappears
61
What phase do the centrioles duplicate?
S phase
62
When does prometaphase occur?
after nuclear envelope disassembles
63
Where do spindle micorotubles grow from? grow to?
grow from centrosomes at
| opposite spindle poles toward the center of the cell
64
What is a kinetochores?
form on each sister chromatids at the the centromere
65
Where do kinetochore microtubules bind?
kinetochores
66
What are nonkinetochore microtubules?
overlap those from the opposite spindle pole
67
What is congression?
chromosomes begin to move to center of cell via assembly and disassembly of microtubules and motor proteins at kinetochores
68
What phase does congression occur?
preometaphase
69
What are the two type of spindles in mitosis?
kinetochores and nonkinetochores
70
What happens in metaphase?
spindle microtubules move chromosomes into alignment to the metaphase plate
71
What is anaphase?
centromeres split, removal of cohesion proteins, sister chromatins pulled apart via microtubules shortening
72
What are the two movements in anaphase?
anaphase A and anaphase B
73
What happens in anaphase A?
kinetochores pulled toward poles, disassemble microtubules into tublin subunits
74
What happens in anaphase B?
moves poles apart, nonkinetochore microtubules elongate the cell
75
What happens in telophase?
1) spindle apparatus disassembles
2) chromosomes decondense and uncoil
3) nuclear envelope forms around each set of sister
chromatids
4) nucleolus reappears
5) RNA transcription resumes
76
Do anaphase A and B occur at the same time?
yes
77
What happens in cytokinesis?
creates 2 daughter cells
78
How does cytokinesis occur in animals, protists, and many fungi?
furrow (contractile ring) girdles the cell and
deepens until it cuts the cytoplasm into two
parts
79
How does cytokinesis occur in plants?
cell plate forms between the daughter nuclei and grows laterally until it divides the cytoplasm in two
80
Where does mitosis occur in some other fungi and protists mitosis?
within the nucleus
81
What is the plane of cytoplasmic division is determined by?
layer of microtubules that persists at the
| former spindle midpoint
82
What is the contractile ring made up of?
actin and myosin
83
Do the steps in mitosis occur exactly after each other?
no, some happens simultaneously, ie contractile ring starts to form before cytokinesis
84
In plant cytokinesis, what role do the vesicles play?
transport plant cell wall material to midline. produced from ER and golgi, and form the plasma membrane
85
What do the motor proteins do in anaphase B?
walk in opposite direction
86
What do nonkinetochore microtubules do in anaphase B?
push the pole apart by growing in length as they slide along
87
What is a common single-celled model?
Saccharomyces cerevisiae yeast
88
What did Saccharomyces cerevisiae yeast lead to the discovery of?
some genes that control the eukaryotic cell cycle
89
Why id Saccharomyces cerevisiae yeast a good model? (4)
◦ Many cells that can be easily visualized
◦ Cell cycle can be paused at a specific phase
◦ All cells can be synchronized at one phase
◦ Mutations are easily generated
90
What are the two irreversible points of the cell cycle?
1) Replication of genetic material (Between G1 and S)
| 2) Separation of the sister chromatids (2n --> 4n)
91
Where can the cell cycle be put on hold?
checkpoints
92
What are the two functions of checkpoints?
1) checked for accuracy and can be halted if there are errors
2) Allows cell to respond to internal and external signals
93
What are the three key checkpoints?
◦ G1/S checkpoint
◦ G2/M checkpoint
◦ Mitotic spindle checkpoint
94
What happens if a checkpoint is inactive?
cell cycle will proceed without stopping
95
What are the molecules responsible for checkpoints?
cyclins and cyclin-dependent kinases
96
What happens in the G1/S checkpoint?
◦ Cell “decides” to divide
| ◦ Primary point for external signal influence
97
What happens in the G2/M checkpoint?
◦ Cell makes a commitment to mitosis
| ◦ Assesses success of DNA replication
98
What happens in the Late metaphase (spindle) checkpoint?
Cell ensures that all chromosomes are attached to the spindle
99
Is the cell cycle under genetic control?
yes
100
Is the cell cycle a true cycle?
yes
101
What does true cycle mean?
its not reversible
102
Are genes transcribed during the cycle?
yes, transcribed needed before their products are needed
103
What are the significants of mutations affecting the cell cycle?
helped to identified the key regulatory pathways
104
What checkpoint is the main point in the cell cycle at which a cell decides whether to divide or not?
G1/S checkpoint
105
Why might the cell cycle stop at G1/S checkpoint?
DNA is damaged by radiation or chemicals. Also if the cell is nutritionally deficient or growth factors are absent.
106
What is the checkpoint where the cell commits to mitosis?
G2/M
107
Why might the cell stop at the G2/M checkpoint?
if DNA was not replicated accurately in S or if the DNA has been damaged by radiation or chemicals
108
What are cyclins and cyclin-dependent kinases made up of?
proteins
109
When are cdks active?
when it is bound to cyclin
110
What is kinases?
enzymes
111
Do the concentration of cyclins change over the cell cycle?
yes
112
When does the mitotic spindle checkpoint occur?
before metaphase in the M phase
113
What happens when a cell begins anaphase?
it is irreversibly committed to completing M
114
What are the 3 classes of cyclins?
G1/S cyclin, S cyclin, and M cyclin
115
What is the role of G1/S cyclin?
required for transition from G1 to S, and to
| commit to DNA replication
116
What does the G1/S cyclin bind to? at what time?
Cdk2 near the end of G1
117
What is the role of S cyclin?
required for initiation of DNA replication and progression
| of the cell through S
118
What does the S cyclin bind to? at what time?
binds to Cdk2 in the S phase
119
What is the role of M cyclin?
required for the transition from G2 to M, and the progression of the cell through mitosis
120
What does the M cyclin bind to? at what time?
M cyclin binds to Cdk1 in G2
121
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What does the fourth class of cyclins ( G1 cyclin) binds to? at what time? Cdk4 and Cdk6 before the G1 /S
transition
```
Cdk4 and Cdk6 before the G1 /S transition
122
What does the fourth class of cyclins ( G1 cyclin) form? function?
form two cyclin–Cdk complexes
needed to move the cell through the G1 checkpoint and proceed from G1 to S
123
What is the M cyclin-Cdk1 complex is also called?
M phase-promoting factor (MPF)
124
What happens to the MPF when the chromosomes are correctly attached to the mitotic spindle
MPF activates another enzyme complex, the anaphase-promoting complex (APC)
125
What happens when activated APC degrades an inhibitor of anaphase?
separation of sister chromatids
126
What does APC direct the degradation of? what does this lead to?
M cyclin, causing Cdk1 to lose its activity
127
What are the roles of Cdks? (3)
1) phosphorylate proteins
2) Primary mechanism of cell cycle control
3) Cdks partner with different cyclins at different points in the cell cycle
128
What was the previous viewpoint of cyclins?
cyclins drove the cell cycle
129
What is the current viewpoint of cycline? Where is this talked about?
Cdk itself is also controlled by phosphorylation (( talks about the discovery of M cyclin-CDK complex)
130
What was Johnson and Rao's experiment?
They fused human HeLa cells at different stages of the cell cycle. Cell fusion produces a single cell with two separate nuclei. The researchers allowed the fused cells to grow and determined whether one nucleus influenced the other in terms of progression through
the cell cycle
131
What were the results of Johnson and Rao's experiment?
DNA synthesis quickly began in the original G1 nucleus. Normally, the G1 nucleus would
not have initiated DNA synthesis until it reached S phase itself, which could have been several
hours later. The result suggested that one or more Molecules that activate S phase are present
in the cytoplasm of S phase cells
found cyclins and cdks (groundwork for, didn't know what they were but discovered their affects)
132
What are internal controls modified by?
external controls
133
What are some examples of external controls
peptide hormones and growth factors
134
What do hormones and growth factors act on the cell by?
reception-transduction-response pattern
135
What happens to the reaction when it is triggered by the activated receptor?
may speed, slow, or stop the progress of cell division
136
What is Contact inhibition? What phase will the cells enter?
stops the cell cycle b/c there are no is no room for division, will enter G0 phase
137
Are cancer cells affected by contact inhibition?
no, they will keep dividing
138
What does metastasis?
cancer cells lose adhesions to other cells and spread throughout the body
139
What are oncogenes?
mutated form of these genes which encode altered versions of these products
140
What does onco mean?
cancer causing
141
What were they trying to find out in the Gorbsky experiment?
How do the chromosomes moves towards the poles?
142
What was the hypothesis for the Gorbsky experiment?
The kinetochore microtubules moved pulling the chromosome towards the poles OR chromosomes
moved by sliding over or along the kinetochore microtubules.
143
What was the set up for the Gorbsky experiment?
Bleached segment of kinetochores and watched what happened
144
What was the result for the Gorbsky experiment?
support the hypothesis that chromosomes move
| by sliding over or along kinetochore microtubules.
145
how did mitosis evolve from binary fission?
Scientists believe that the ancestral division process was binary fission and that mitosis evolved from that process
146
Does the cyclin bind to another protein? Name the protein.
Yes, cdk
147
Does the other protein need the cyclin to work?
yes
148
When Cyclin E and the other protein (Name?) form a complex, does the cell move through the cell cycle? Name the phases
cdk, G ---> S
149
What type of cyclin is cyclin E?
G1/S cyclin
