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Cell Division Flashcards

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1
Q

A part of ______ states that all cells arise from
pre-existing cells through ______

A

1) Cell Theory
2) Cell division

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2
Q

Genome

A
  • all the DNA in a cell.
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3
Q

Chromosomes

A
  • separate DNA molecules that make up the entire genome.
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4
Q

Homologous chromosome pairs

A
  • two different versions of the same chromosome number. One is inherited from mother and one from father.
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5
Q

Sister chromatids

A
  • identical, attached copies
    of a single chromosome that form dyads.
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6
Q

Dyads

A
  • replicated chromosomes containing
    two sister chromatids that look like an “X”.
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7
Q

Centromeres

A
  • regions of DNA that connect
    sister chromatids in a dyad.
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8
Q

Kinetochores

A
  • proteins on the sides of
    centromeres that help microtubules pull sister
    chromatids apart during cell division.
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9
Q

Karyokinesis

A
  • division of the nucleus.
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10
Q

Cytokinesis

A
  • physical division of the
    cytoplasm and cell membrane.
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11
Q

Parent cell

A
  • one parent cell produces two daughter cells after division.
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12
Q

Ploidy

A
  • describes the number of chromosome sets found in the body. Humans are diploid
    because they contain two sets of chromosomes (46 chromosomes, 23 pairs),
    one from each parent. However, they also have haploid cells (gametes) that only contain one chromosome set (23 chromosomes).
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13
Q

Sex chromosomes

A
  • one pair in the human
    body; they determine sex.
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14
Q

Autosomes

A
  • 22 pairs in the human body; they are non-sex chromosomes.
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15
Q

Gametes

A
  • haploid cells (sperm and eggs).
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16
Q

Germ cells

A
  • diploid cells that divide by meiosis to produce gametes.
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17
Q

Gametocyte

A
  • eukaryotic germ cells that can either divide to form more gametocytes or
    produce gametes.
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18
Q

Somatic cells

A
  • all body cells excluding the
    gametes. Diploid in humans.
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19
Q

Stages in Cell Cycle

A

1) G1
2) G0
3) S
4) G2
5) M phase

1) => 4) = interphase

Go = Gap Phase 1 (G1) of interphase
Sam = Synthesis Phase (S) of interphase
Go = Gap Phase 2 (G2) of interphase
Make = Mitosis of the M phase
Cake = Cytokinesis of the M phase

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20
Q

G1 (gap phase G1)

A
  • cell grows in preparation
    for cell division. Also checks for favorable
    conditions. If favorable, the cell will enter the S
    phase. If unfavorable, the cell will enter G0
    phase.
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21
Q

G0 phase

A
  • cells still carry out their
    functions but halt in the cell cycle. Cells
    that do not divide are stuck here.
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22
Q

Synthesis phase (S)

A
  • cell replicates its genome
    here and moves to G2 phase when completed.
    Centrosome duplicates.
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23
Q

Gap phase 2 (G2)

A
  • cell continues to grow and
    prepare for cell division by checking DNA for any errors after replication. Also checks for mitosis promoting factor (MPF) aka maturation promoting factor, which needs to be present in adequate amounts for cell
    cycle continuation. Organelles are replicated
    here.
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24
Q

Microtubule Organizing Centers (MTOCs)

A
  • are present in eukaryotic cells; they organize extension
    of microtubules, which are made of the protein
    tubulin. MTOCs are responsible for forming the
    spindle apparatus, which guides chromosomes
    during karyokinesis.
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25
Centrosomes
-are organelles found in animal cells that contain a pair of centrioles. They act as microtubule organizing centers (MTOCs).
26
_______ in the spindle apparatus:
1) Microtubules
27
Kinetochore microtubules
- extend from centrosomes and attach to kinetochores on chromosomes.
28
Astral microtubules
- extend from centrosomes to the cell membrane to orient the spindle apparatus.
29
Polar microtubules
- extend from the two centrosomes and connect with each other. They push centrosomes to opposite ends of the cell.
30
Centrioles
- are hollow cylinders made of nine triplets of microtubules (9x3 array). Centrosomes are located near the nucleus and contain a pair of centrioles oriented at 90 degree angles to one another (attached to each other by interconnecting fibers). They replicate during the S phase of the cell cycle so that each daughter cell after cell division has one centrosome.
31
Pericentriolar material
- surrounds the centrioles and is responsible for microtubule nucleation (anchoring tubulin to start microtubule extension).
32
Cilia and flagella structure
- have nine doublets of microtubules with two singles in the center (9+2 array). They are produced by a basal body, which is initially formed by the mother centriole (older centriole after S phase replication) attaching itself to the cell membrane.
33
The M phase
- is the stage in the cell cycle where karyokinesis and cytokinesis occur. Mitosis is a type of karyokinesis (nuclear division) that involves a diploid parent cell dividing into two diploid daughter cells.
34
Four phases of mitosis:
1) Prophase 2) Metaphase 3) Anaphase 4) Telophase
35
Prophase
- chromatin condenses into chromosomes (X-shaped dyads). The nucleolus and nuclear envelope disappear. Spindle apparatus forms.
36
Metaphase
- the spindle apparatus guides the chromosomes to the metaphase plate (midpoint of cell) in a single file.
37
Prometaphase
- stage after prophase but prior to the onset of metaphase. Here, the nuclear envelope fragments, and spindle apparatus microtubules attach to the kinetochores of chromosomes.
38
Anaphase
- kinetochore microtubules shorten to pull sister chromatids apart. Now, the sister chromatids are considered separate chromosomes. Chromosome number doubles.
39
Telophase
- chromosomes have segregated and nuclear membranes reform. In addition, nucleoli reappear and chromosomes decondense into chromatin. Only DNA from eukaryotic cells is organized into chromatin.
40
Cytokinesis
is the physical separation of the cytoplasm and cell membrane into two daughter cells.
41
In _______, cytokinesis begins in ________ with the formation of a cleavage furrow. The cleavage furrow is a contractile ring of _______ and ________ motors that pinches the cell into two.
1) animal cells 2) late anaphase 3) Actin microfilaments 4) myosin
42
In ______, cytokinesis begins in ______ with the formation of a cell plate. The cell plate is created by vesicles from the ________ and ends up producing the middle lamella (cements _______ together).
1) Plants Cells 2) Telophase 3) Golgi Apparatus 4) Plant cells
43
The _____ influences cell division through ______ to growth and regulation to prevent cancerous growth.
1) Cell cycle 2) limitations
44
Functional Limitations of Cell Cycle
1) Surface to volume ratio (S/V) - cell division occurs when volume is too large because cells rely on the surface area of their cell membrane for transport of material. Decrease in S/V ratio leads to cell division. 2) Genome to volume ratio (G/V) - cell division occurs when the volume of the cell is too large to be supported by the limited size of the genome. Decrease in G/V ratio leads to cell division.
45
Cell Specific Regulation
1) Cell specific checkpoints 2) Cyclin-dependent kinases (CDKs) 3) Growth Factors 4) Density dependent inhibition 5) Anchorage dependence
46
Cell specific checkpoints (cell specific regulation)
- G1 restriction point (checks for favorable conditions to grow, enters G0 phase if unfavorable), end of G2 (checks accuracy of DNA replication and MPF levels), and M checkpoint (during metaphase, checks for chromosomal attachment to spindle fibers).
47
Cyclin-dependent kinases (CDKs)
- phosphorylate certain substrates to signal cell cycle progression. Activated by cyclin, a protein that cycles through stages of synthesis and degradation.
48
Growth factors
- bind to receptors in the plasma membrane to signal for cell division.
49
Density dependent inhibition
- halting of cell division when density of cells is high.
50
Anchorage dependence
- cells divide only when attached to an external surface.
51
Mitosis
- is used to increase the number of cells in an organism, whereas binary fission is used by archaea, bacteria, and certain organelles to reproduce. -During the S phase of the cell cycle, a human’s 46 chromosomes are duplicated. Afterwards, there are still 46 chromosomes but also 92 chromatids. They line up in metaphase individually. - During anaphase of mitosis, sister chromatids split. This produces 92 separate chromosomes, which are also counted as 92 chromatids. Each separated cell will have 46 chromosomes (46 chromatids). These cells are diploid.
52
During _______, organisms will replicate their genome while cell division is happening (no ______ for DNA replication). Also, there is no _______.
1) binary fission 2) S phase 3) Spindle Apparatus
53
Meiosis
- produces four haploid daughter cells from one diploid parent cell. It does this by repeating the steps of karyokinesis twice. Meiosis can be divided into meiosis I (homologous chromosomes separate) and meiosis II (sister chromatids separate).
54
Meiosis I (reductional division)
- produces two haploid daughter cells through separation of homologous chromosomes. - prophase 1, metaphase 1, anaphase 1, telophase 1 - For meiosis I, a human goes through the same DNA replication in S phase as mitosis that results in 46 chromosomes and 92 chromatids. However, during metaphase the chromosomes double up as shown below:
55
Prophase I
- chromatin condenses into chromosomes (X-shaped dyads). The nucleolus and nuclear envelope will disappear. Homologous chromosomes pair up and crossing over occurs.
56
Synapsis
- the pairing up of homologous chromosomes to form tetrads (aka bivalents).
57
Synaptonemal complex
- protein structure that forms between homologous chromosomes during synapsis.
58
Tetrads (bivalents)
- pair of two homologous chromosomes each with two sister chromatids.
59
Chiasmata
- where two chromosomes of a homologous pair cross over during synapsis, causing genetic recombination.
60
Genetic recombination
- exchange of DNA between chromosomes to produce genetically diverse offspring.
61
Metaphase I
- tetrads randomly line up double-file on the metaphase plate; this contributes to genetic diversity.
62
Anaphase I
- kinetochore microtubules shorten to separate homologous chromosomes from each other. Will not begin unless at least one chiasmata has formed within each tetrad.
63
Telophase and Cytokinesis I
- after tetrads have been pulled to opposite poles, nuclear membranes reform. In addition, nucleoli reappear and chromosomes decondense into chromatin. A Cleavage furrow forms in animal cells and a cell plate forms in plant cells.
64
Meiosis II
- is very similar to mitosis because sister chromatids are separated. Two haploid cells divide into four haploid daughter cells. - Meiosis II is very similar to mitosis and involves chromosomes lining up individually in metaphase. During anaphase, sister chromatids are separated, resulting in 23 chromosomes (23 chromatids) in each daughter cell. These cells are haploid.
65
Prophase II
- chromatin condenses into chromosomes (X-shaped dyads). The nucleolus and nuclear envelope will disappear. Spindle apparatus forms. No crossing over occurs.
66
Metaphase II
- chromosomes line up single-file at the metaphase plate just like in mitosis.
67
Anaphase II
- kinetochore microtubules shorten to pull sister chromatids apart. Sister chromatids become separate chromosomes and chromosome number doubles.
68
Telophase and Cytokinesis II
- nuclear membranes reform, nucleoli reappear, and chromosomes decondense into chromatin (only in eukaryotic cells). Four haploid daughter cells are produced in total. ******Refer to page 30 of DAT bootcamp for table of chromosomal numbers.*****
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