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BIO1111- Mary-Susan Pottsantone > Exam 3- Mitosis and Chromosomes > Flashcards

Exam 3- Mitosis and Chromosomes Flashcards

1
Q

What is the cell cycle?

A

Orderly set of stages and substages between one division and the next

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2
Q

What happens prior to the next division?

A
  • cell performs normal activities
  • cell grows larger
  • The number of organelles doubles
  • DNA is replicated
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3
Q

What are the two major stages of the cell cycle?

A
  • Interphase ( 90%)
  • mitotic phase
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4
Q

What is the order of interphase?

A

G1 —> S—> G2

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5
Q

Do all cells turn over/ go through mitosis at the same rate?

A

No

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6
Q

Why do cells go through the cell cycle?

A

growth, cell replacement, Asexual reproduction

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7
Q

What are the different kinds of rates that cells could go through?

A

constantly cycling: always cycling
inducible: can cycle when signaled
non-cycling ( G0) - never cycle

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8
Q

what is an example of non-cycling cells?

A

skeletal and neurons

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9
Q

What happens during G1 ( specific)?

A

GROWTH
- recovery from previous division
- cell doubles organelles
- make raw materials for DNA synthesis
- the longest part of the interphase

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10
Q

What happens during the S phase?

A

SYNTHESIS
- DNA replication
- Chromosomes enter w/ 1 chromatid each
- Chromosomes leave w/ 2 identical chromatids each
- shorter than G1

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11
Q

What happens in G2?

A

GROWTH
- between DNA replication and the onset of mitosis
- cell synthesis proteins necessary ( lots of microtubules
-shorter than the S phase

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12
Q

What happens in the Mitotic Phase ( general)

A
  • Mitosis
  • Cytokinesis
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13
Q

What is Mitosis?

A

Nuclear division
- daughter chromosomes distributed to 2 daughter nuclei

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14
Q

What is cytokinesis?

A

cytoplasm division
- results in two genetically identical daughter cells

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15
Q

What are the external signals that control the cell cycle?

A

Growth factors
- received at the plasma membrane
- cause completion of cell cycle
- protein based
- often operate w/ second messenger mechanisms
- regulate cell division

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16
Q

What are the internal signals that control the cell cycle?

A
  • cyclin dependant kinases
  • stops at G1, G2, or M
  • allows time for any damage to be repaired
  • Mitosis Promoting Factor
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17
Q

What are cyclins?

A

increase and decrease as the cell cycle continues

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18
Q

What are the internal factors at G1?

A
  • P53 : protein that will stop G1 to allow for corrections
  • Apoptosis if DNA is damaged beyond repair
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18
Q

What are the internal signals at G2?

A

Mitosis will occur if DNA has replicated properly. Apoptosis if DNA is damaged

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19
Q

What are the internal signals at M?

A
  • spindle assembly checkpoint
  • polo-like and aurora kinases: make sure the chromosomes are properly aligned
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20
Q

What are the Mitosis Promoting Factors ( MPF)?

A

-threshold amount
- cyclin + kinase = MPF

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21
Q

What is chromatin?

A

loosely coiled: intertangled

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22
Q

What is a chromosome?

A

tightly condensed; visible

23
Q

When is DNA visible?

A

DNA is visible when it is a duplicated chromosome; getting ready to divide

24
Q

What are all the cells in our body? diploid or haploid?

A

Diploid= 2n

25
Q

What are the only cells in the body that are haploid?

A

sperm and egg cells
- haploid = n

26
Q

How many different types of chromosomes do humans have?

A

23

27
Q

How many chromosomes do most cells in the human body have?

A

46
- 23 from father
- 23 from mother

28
Q

what is a karyotype?

A

the way in which we image chromosomes?
- all 23 pairs of chromosomes laid out
- 1-22 are autosomes
- 23 is the sex chromosomes

29
Q

What are autosomes?

A

specify body traits

30
Q

What are homologous chromosomes?

A

homologs
- two chromosomes that carry the same kind of genetic traits

31
Q

how do you get a karyotype?

A
  • get a blood sample
  • take dividing white blood cells and stop them before they divide
  • photograph chromosomes
  • match homologs
32
Q

Do homologs carry the same form of genes?

A

NO, carry the same genes but not the same forms of that gene

33
Q

Where does the centrosome start at the beginning of the mitotic phase?

A
  • outside of the nucleus
34
Q

What is the MTOC?

A

microtubule organizing center
- the job is to organize the mitotic spindle
- contains many fibers
- each composed of a bundle of microtubules

35
Q

How do the centrioles move through interphase?

A

-2 barrel shaped centrioles
- oriented at 90* angles
- centrosome replicated in S phase
- centrosomes in G2 move toward opposite sides of the cell
- forming the poles

36
Q

What occurs in prophase?

A

make space for movement of genetic material

-nuclear envelope disintegrates
- nucleolus disappears
- spindle begins to take shape
- two centrosomes move away from each other
-form microtubules asters

37
Q

What are asters

A

microtubules in star like arrays

38
Q

What happens in Prometaphase?

A
  • centromere of each chromosome develops 2 kinetochores
  • hook up specialized microtubules
39
Q

what are the kinetochores and how do they work?

A

specialized protein complex
- one over each sister chromatid
- physically hook sister chromatids up with specialized microtubules

40
Q

What are the three specialized microtubules?

A
  • kinetochore
  • astral
  • polar
41
Q

What are the kinetochore fibers?

A

anchor to kinetochore proteins and hook up with sister chromatids

42
Q

what are astral fibers?

A

stabilize position of the pole
- run from pole to plasma membrane

43
Q

what are the polar fibers?

A

run from the pole toward midline of cell that don’t attach to anything

44
Q

What happens in metaphase?

A

chromosomes are lined up on the metaphase plate
- chromosomes pulled around by the kinetochore
- 46 chromosomes all lined up in the middle

45
Q

What property of microtubules lets it pull the chromosomes?

A

microtubules have the ability to simultaneously lengthen and shorten.

46
Q

What happens in anaphase?

A
  • centromere dissolves releasing sister chromatids
  • sister chromatids separate ( daughter chromosomes)

-spindle microtubules attached to kinetochores shorten, while those not attached lengthen to push poles apart

47
Q

What happens in telophase?

A

spindle disappears
- now two clusters of daughter chromosomes
- still 2 of each type with all types represented
- clusters are daughter nuclei
- nuclear envelopes form around the two incipient daughter nuclei
- chromosomes uncoil and become diffused chromatin again
- nucleolus reappears in each daughter nucleus

48
Q

What occurs during cytokinesis?

A

division of cytoplasm
- allocates mother cell’s cytoplasm equally to daughter cells
- encloses each in its own plasma membrane
- often begins in anaphase
- cleavage furrow appears between daughter nuclei
- formed by contractile ring of actin filaments

49
Q

How do prokaryotes reproduce?

A

Asexual reproduction
- binary fission

50
Q

Are mitosis and apoptosis opposing forces? T/F

A

True

51
Q

What are caspases?

A

Apoptosis enzymes
- ordinarily held in check by inhibitors
- can be unleashed by internal or external signals

52
Q

What are some diseases that can result from too much apoptosis?

A
  • Alzheimer
  • Huntington
  • Parkinsons
53
Q

What are some diseases that can result from too little apoptosis?

A
  • cancer
  • autoimmune disease
54
Q

Why does our body need apoptosis?

A
  • remove abnormal cells
  • keep a balance within the body
55
Q

What are the intrinsic pathways that lead to apoptosis?

A

UV, Chemotherapy, ER stress

56
Q

What are the extrinsic pathways that lead to apoptosis?

A

death ligand and receptor activates enzymes to trigger apoptosis

BIO1111- Mary-Susan Pottsantone (17 decks)

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