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BIO112 > Unit 2 Chapter 11: The Cell Cycle + Mitosis > Flashcards

Unit 2 Chapter 11: The Cell Cycle + Mitosis Flashcards

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1
Q

What are the 3 mysteries of heredity

A
  1. all organisms come from other organisms
  2. children resemble their parents
  3. siblings are not identical
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2
Q

What is the cell theory (3 points)

A
  1. all organisms consist of cells
  2. cells divide to produce new cells
  3. higher organisms fuse their cells to produce a new organism
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3
Q

What are mitosis and cytokinesis responsible for (3 events)

A
  1. growth
  2. wound repair
  3. reproduction
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4
Q

What is asexual reproduction

A

produces offspring that are genetically identical from the parent, ie. mitosis

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5
Q

What is a chromosome

A
  • a single string of DNA
  • linear in eukaryotes
  • circular in bacteria
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6
Q

What does DNA do

A

stores the cell’s heredity info or genetic material

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7
Q

What is a gene

A

a length of DNA that codes for a particular protein or RNA found in the cell

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8
Q

Why can we see chromosomes

A

they condense by associating with histones (proteins) and forming chromatin

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9
Q

What is a chromatid

A

one of the DNA copies in a replicated chromosome

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10
Q

What is a centromere

A

the specialized region that joins 2 chromatids togethe

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11
Q

What are sister chromatids

A

chromatids from the same chromosome

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12
Q

What is a karyotype

A

a way of organizing and identifying chromosomes

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13
Q

What are homologs

A

nearly identical pairs of chromosomes

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14
Q

What are mitotic chromosomes

A

2 chromosomes bound by a centromere (technically thats 2 pieces of DNA but we still call them chromosomes)

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15
Q

What does “segregating is exacting mean”

A
  • organisms need at least 1 of each chromosome because each has specific genetic material
  • usually we need EXACTLY one of each
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16
Q

What is the cause of down syndrome

A

3 chromosome 21

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17
Q

What is interphase

A

DNA is found in nucleus associated with histones (as chromatin)

  • active time: cell is either growing and preparing to divide or performing its specialized function
  • includes S phase
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18
Q

What is S-phase

A
  • in interphase

- DNA is replicated

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19
Q

What is G2

A

the time lag that occurs after S phase and before M phase

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20
Q

What is G1

A

the time lag that occurs after M phase and before S phase (longer than G2)

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21
Q

Why are G2 and G1 necessary

A

the cells need to grow and synthesize enough organelles so its daughter cells will be normal in size and function

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22
Q

What is mitosis

A

the process where cells divide to make identical copies of themselves and each daughter cell inherits one copy of each chromosome

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23
Q

What do cohesins do

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A

protein rings made of 3 subunits that encircle 2 pieces of DNA to keep them together until they receive the division signal

24
Q

What do condesins do

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A

protein rings made of 3 subunits that encircle DNA and stabilize loops in the same piece of DNA (to make them smaller/more condensed)

25
What are the steps of mitosis
IPPMAT - interphase - prophase - prometaphase - metaphase - anaphase - telophase/cytokinesis
26
What happens in prophase
-chromosomes condense -spindle apparatus forms (centrosomes move to poles)
27
What is the spindle apparatus
- consists of microtubules (polar and kinetochore) | - produces forces that pull chromosomes to poles and push cell poles away from eachother
28
What are polar microtubules
extend from each spindle (centrosome which contains centrioles) and overlap each other in middle of cell
29
What are kinetochore microtubules
attach to chromosomes (kinetochore, at centromere region) | -each chromosome has 2 kinetochores
30
What happens in prometaphase
- nuclear envelope disappears - kinetochore microtubules attach to one of the 2 sister chromatids of each chromosome at the kinetochore - centrosomes continue moving to poles, kinetochore microtubules start moving chromosomes to center
31
What happens in metaphase
- cells line up in centre (metaphase plate) | - polar microtubules create this pole to pole connection by overlapping
32
What happens in anaphase
- cohesins split - sister chromatids are pulled apart to opposite poles (replicated chromosomes separate into 2 identical sets of unreplicated chromosomes)
33
What happens in telophase/cytokinesis
- nuclear envelope reforms - spindle apparatus disappears - chromosomes decondense - 2 nuclei form - cell pinches off and divides (cleavage furrow) (actin and myosin)
34
What is cytokinesis like in plants
vesicles from golgi line up and from a cell plate which builds up and divides the 2 cells
35
Which ends of the microtubule attach to the kinetochore
plus end
36
How do chromosomes move during mitosis
- the kinetochore microtubules shorten because tubulin subunits are lost from plus ends - as anaphase occurs, proteins in kinetochore catalyze the loss of tubulin subunits at plus ends of the tubules, while proteins walk towards minus end - this pulls chromosomes to opposite sides of the cell
37
What type of cells does mitosis produce
diploid
38
How is the cell cycle regulated
various cyclins which are the second MPF (mitosis promoting factor)subunit - cyclin concentrations fluctuate throughout the cell - protein kinase subunit of MPF is cyclin-dependent kinase - cyclin functions as regulatory protein and kinase catalyzes the phosphorylation of other proteins to start mitosis
39
How is MPF activated
when one of the phosphate groups on the Cdk subunit drops off in G2 and causes shape to change
40
How is MPF deactivated
during anaphase, enzymes degrade MPF's cyclin subunit which leads to its own destruction
41
What is the G1 checkpoint
-between G1 and S phase -establishes whether cell will continue through cycle and divide or go to G0 factors: -size-cells are arrested if too small -availability of nutrients-arrested if nutrient conditions are poor -social signals -damage to DNA -if damaged DNA is not stopped, can lead to uncontrolled cell division, cells will enter cell cycle without growing getting smaller each time
42
What is the G2 checkpoint
-after S phase and between G2 and M phase -if DNA is damaged or not replicated correctly, cells can't pass -size could also be a factor -
43
What is the S to G2 checkpoint
- ensures cells are replicated - hydroxyurea blocks chromosome replication so cells stay in S phase - caffeine disables this checkpoint
44
What happens when both hydroxyurea and caffeine are added
DNA cannot replicate, still enters mitosis and then everything dies
45
What is the metaphase checkpoint
- if not all chromosomes attach to spindle properly, mitosis stops at metaphase - anaphase delayed until everything attaches properly
46
What is cancer and how does it arise
- the uncontrolled division of cells | - arise from cells in which cell checkpoints have failed
47
What are the 2 defects of cancerous cells
1. defects that make proteins required for cell growth active when they shouldn't be 2. defects that prevent tumor suppressing genes from shutting down the cell cycle
48
How do cells become malignant and cancerous
if they can detach from the original tumour and invade other tissues
49
What is the G0 phase
-where mature cells go, when their cell cycle is arrested in G1
50
Which check point is most crucial when it comes to cancer
G1 because it looks for external signals which can be manipulated
51
What is cancer characterized by
1. loss of control at G1 checkpoint which leads to crazy cell division 2. metastasis
52
Progression through the cell cycle is regulated by oscillations in the concentration of
cyclins
53
What signals a cell to divide
the binding of Cyclin D (only in G1) and Cdk4 (always in cell)
54
Which cells don't bother with cytokinesis
muscle cells
55
How many chromosomes do humans have
46, 23 pairs

BIO112 (19 decks)

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