Chapter 12: The Cell Cycle Flashcards
(87 cards)
1
Q
How do new cells arise?
A
through the division of pre-existing cells
2
Q
How do bacterial cells divide?
A
By binary fission
3
Q
Define Binary fission
A
asexual reproduction
4
Q
how many times does cell division occur in bacteria
A
one
5
Q
How many times does cell division occur in eukaryotes?
A
twice
6
Q
In Eukaryotes, what are the two types of cell division?
A
- Meiosis
- Mitosis
7
Q
Define Meiosis
A
results in the production of gametes
8
Q
define gamates
A
reproductive cells (egg & sperm)
9
Q
Individual sex cells are considered (diploid/haploid)
A
haploid
10
Q
Where does meiosis occur?
A
In testes for men
In ovaries for women
11
Q
Define Mitosis
A
results in the production of somatic cells
12
Q
define somatic cells
A
All other types of cells excluding sex cells
13
Q
In mitosis, daughter cells are genetically (varied/identical) from(to) the parent cell.
A
identical
14
Q
What are the functions of mitosis?
A
- Growth
- Repair
- Asexual reproduction
15
Q
What is a chromosome?
A
DNA wrapped around histone proteins
16
Q
Chromosomes have _____ which encode a specific (DNA/RNA) sequence
A
genes; RNA
17
Q
True or False
Chromosomes have genes which encode for proteins
A
True
18
Q
True or False
Chromosomes have genes which encode for a specific DNA sequence
A
False
Chromosomes encode for a specifc RNA sequence
19
Q
Around how many genes are in chromosomes?
A
100s-1000s
20
Q
True or False
The purpose of meiosis is to replicate chromosomes
A
False;
That is the purpose of mitosis
21
Q
True or False
The purpose of mitosis is to replicate chromosomes
A
True
22
Q
Each of the DNA copies in a replicated chromosome is called a ________
A
chromatid
23
Q
Define sister chromatid
A
chromatids from the same chromosome
24
Q
A replicated chromosome consists of two (chromatins/ chromatids /chromosomes)
A
chromatids
25
**True or False**
A replicated chromosome with two chromatids is considered two chromosomes.
False
It is still considered a **_single chromosome_**
26
**True or False**
Chromosomes are joined together at a specialized region called the centromere
False
**_Chromatids_** are joined together at a specialized region called the centromere
27
**True or False**
Chromatids are joined together at a specialized region of the chromosome called the centromere
True
28
The material that makes up eukaryotic chromosomes:
chromatin
29
consists of a DNA molecule complexed with histone proteins:
Chromatin
30
A structure composed of a DNA molecule and associated proteins:
Chromosomes
31
One strand of a replicated chromosome, with its associated proteins:
Chromatid
32
Two strands of a replicated chromosome:
sister chromatids
33
**True or False**
When sister chromatids separate during mitosis, they become independent chromosomes
True
34
**True or False**
When sister chromatids separate during meiosis, they become independent chromosomes
False
When sister chromatids separate during **_mitosis_**, they become independent chromosomes
35
The structure that joins sister chromatids:
Centromere
36
The structures on sister chromatids where microtubules attach
Kinetochores
37
Any structure that organizes microtubules:
Microtubule-organizing center
38
The microtubule organizing center in animals and plants:
Centrosome
39
Cylindrical structure that comprise microtubule, located inside animal centrosomes
Centrioles
40
How many phases does _the cell cycle_ have?
Two phases
41
What are the phases of the _cell cycle?_
1. Mitotic (M) phase
2. Interphase
42
Which phase of the cell cycle is also known as the ***dividing phase***
Mitotic (M) phase
43
Which phase of the cell cycle is also known as the ***non-dividing phase***
Interphase
44
define **mitotic (M) phase**
division of replicated chromosomes into 2 genetically identical daughter cells
45
define ***Interphase***
the period of metabolism, growth, DNA replication, and production of cytoplasm.
46
Name the phases within *Interphase*
G1 , S (synthesis) , G2,
47
What happens in ***G1 phase***?
organelles replicate and a cytoplasm is produced
48
What happens in ***S (synthesis) phase***?
chromosomes replicate, resulting in genetically identical sister chromatids
49
What happens in ***G2 phase***?
organelles replicate and a cytoplasm is produced
50
**True or False?**
Cell cycle length can vary greatly among cell types
True
51
**True or False**
The length of the cell cycle is consistent in all cell types
False
Cell cycle length **varies** among cell types
52
In interphase, which phase is responsible for the variation in length of the cell-cycle?
G1 Phase
53
Rapidly dividing cells have a (_shorter/longer_) G1 phase
shorter
54
What happens to non-dividing cells during Interphase?
They are permanently stuck in G1 phase
55
For non-dividing cells, their arrested stage is known as the:
G0 state
56
Which phases of the cell cycle have *_checkpoints_* and how many do they have?
G1 has one checkpoint
G2 has one checkpoint
mitosis has two checkpoints
57
What permits a cell to pass the G1 checkpoint?
* Cell must be an adequate cell size
* sufficient nutrients
* undamaged DNA
* must have its social signals (growth factors)
58
What permits a cell to pass the G2 checkpoint?
* Chromosomes must be successfully replicated
* DNA is undamaged
* Activated MPF is present
59
What is the key signal to initiate/induce mitosis?
Activated mitosis promoting factor (MPF)
60
What permits a cell to pass the M-phase checkpoints?
1. chromosomes have attached to the spindle apparatus
2. chromosomes have properly segregated and MPF is present
61
Where is MPF found?
in the cytoplasm of eukaryotic cells
62
MPF is composed of two distinct subunits, what are they?
* Cyclin -dependent kinase (Cdk)
* Cyclin
63
Define ***Cdk***
an enzyme that catalyzes the transfer of a phosphate group (from ATP to protein), initiating mitosis
64
Define ***Cyclin***
a subunit that functions as a regulatory protein
65
The concentration of MPF cyclin increase during ______ and peaks in \_\_\_\_\_\_\_.
interphase; M-phase
66
**True or False?**
The concentration of MPF Cdk increases during interphase and peaks in M-phase
False
The concentration of MPF **_cyclin_** increases during interphase
67
When is MPF protein kinase active?
only when bound to the cyclin subunit
68
MPF is more active when cyclin concentrations are (_low/high)_
high
69
Cdk catalyzes ____________ of other proteins to start \_\_\_\_\_\_\_
phosphorylation; M-phase
70
What event in mitosis does MPF deactivate?
Anaphase
71
What happens to MPF during anaphase?
an enzyme complex degrades MPF's cyclin subunit, which prevents further cell division
72
What happens when Cdk binds to cyclin?
Cdk becomes phosphorylated at two sites, making Cdk inactive
73
When and how does MPF become activated?
Late in the G2 phase, one phosphate group drops off the Cdk unit
74
Once MPF is activated, mitosis is triggered by:
the condensation of chromosomes and formation of the mitotic spindle apparatus
75
Name the events in mitosis (In order)
1. Prophase
2. Prometaphase
3. Metaphase
4. Anaphase
5. Telophase
76
In Mitosis, what happens in ***prophase?***
chromosomes condense and mitotic spindles form
77
How do mitotic spindles form?
From a microtubule-organizing center (centrosome)
78
What are microtubules composed of?
Alpha & beta tubular dimers
79
What do microtubules do?
they push the poles away from each other and pulls the chromosomes towards the poles the during mitosis
80
In Mitosis, what happens in ***prometaphase?***
the nuclear envelope breaks down and the nucleolus disappears
81
In Mitosis, what happens in ***Metaphase*** ?
* Mitotic spindle is completely formed and the motor proteins on the kinetochore microtubules pull each chromosome
* Metaphase plate formed
82
In mitosis, what happens in ***anaphase***?
centromeres split, sister chromatids are pulled by the spindle fibers toward opposite poles of the cell.
83
In mitosis, what happens in ***Telophase?***
a new nuclear envelope begins to form around each set of chromosomes
84
In what stage of mitosis does the mitotic spindle disintegrate?
Telophase
85
In what stage of mitosis do the chromosomes begin to decondense?
Telophase
86
When is mitosis considered complete?
when two independent nuclei have formed
87
