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Biology 151 (Semester 1) > Chapter 12 > Flashcards

Chapter 12 Flashcards

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1
Q

cell cycle

A

life of a cell from the time its formed (during division of parent cell) to its own division into two daughter cells

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2
Q

genome

A

cell’s genetic information
o Prokaryotic genome: 1 single DNA molecule
o Eukaryotic genome: multiple DNA molecules

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3
Q

chromatin

A

entire complex of DNA and proteins which form chromosomes

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4
Q

chromosomes

A

packages of DNA molecules

• Each DNA molecule is long, linear chain of proteins

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5
Q

gene

A

specifies an organism’s inherited traits

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6
Q

somatic cell

A

has nuclei which contains 46 chromosomes (made up of 2 sets of 23)

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7
Q

Gametes

A

reproductive cells—sperm and eggs
o Humans have one set of 23 chromosomes
o Vary among species

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8
Q

sister chromatid cohesion

A

attachment of both sister chromatids to the cohesins

o This attachment is reinforced by proteins bounded to the centromeric DNA

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9
Q

centromere

A

a place filled with chromosomal DNA where the chromatid is attached most closely to its sister chromatid

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10
Q

mitosis

A

division of genetic material in nucleus

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11
Q

Interphase

A

o Cell grows by producing proteins and organelles (that live in the cytoplasm) such as mitochondria and endoplasmic reticulum
o 90% of the cell cycle
o Centrosome duplicates- forming 2 centrosomes
• Centrosomes are located by nucleus
• Includes: G1, S, G2

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12
Q

G1 (Interphase)

A
  • Cell grows

* Has most variable time length

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13
Q

S (Interphase)

A
  • DNA synthesis
  • Cell continues to grow
  • Duplicates its chromosomes
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14
Q

G2 (Interphase)

A
  • Shortest part of cell cycle
  • Cell grows some more and completes preparation for cell division
  • Nuclear envelope surrounds the nucleus
  • Nucleus contains 1 or more nucleoli
  • Single centrosome duplicates to form 2.
  • Approximately 4-6 hours long
  • Cannot see chromosomes here because they haven’t yet condensed
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15
Q

Prophase

A
  • Mitotic spindle begins to form
  • Formed in the cytoplasm
  • Meanwhile, other microtubules of the cytoplasm partially disassemble. (This provides the material used to construct the spindle).
  • Chromatin fibers become coil to become chromosomes
  • Nucleoli disappear
  • Centrosomes move away from each other
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16
Q

mitotic spindle

A

• Fibers made of microtubules and other proteins
• Attach to kinetichores
 Formed in the cytoplasm

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17
Q

asters

A

parts of the shorter microtubules that extend from the centromere

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18
Q

Prometaphase

A
  • Nuclear envelope breaks into fragments.
  • Chromosomes are even more condensed.
  • Each of the 2 chromatids on each duplicated chromosome has a kinetochore
  • Some kinetochores bind to microtubules becoming ‘microtubule kinetichores’. These jerk the chromosomes back and forth.
  • Nonkinetichore microtubules interact with the kinetochore microtubules on the other end of the spindle
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19
Q

Kinetichore

A
  • Structure made of proteins that have assembled on specific sections of DNA at each centromere
  • Links chromosomes to microtubules
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20
Q

microtubule kinetichores

A

the result of kinetochores attaching to spindle microtubules during prometaphase

21
Q

cohesin

A

protein complex that regulates the separation of sister chromatids during cell division

22
Q

Metaphase

A

• Centromeres are now at opposite ends of the cell.
• Chromosomes arrive at metaphase plate. Centromeres lie directly on this plate.
 Metaphase plate: plane equidistant from spindle’s 2 poles
• The kinetochores of all sister chromatids are attached to kinetochore microtubules coming from the opposite poles.
• Microtubules of the asters are now in contact with the plasma membrane
• Spindle complete!

23
Q

Anaphase

A

• Shortest stage of mitosis (a few min. long)
• Begins when cohesin proteins begin to split causing 2 sister chromatids to separate
 This results in each chromatid becoming a full-fledged chromosome
• Daughter chromosomes move toward opposite ends of the cell as kinetochore microtubules shorten (Centromere first at at 1 /min)
• Cell elongates as NONkinetichore microtubules lengthen
• By the end of the phase, each side of the cell has complete set of chromosomes

24
Q

Telophase

A
  • Two daughter nuclei form
  • Nuclear envelopes arise from fragments of parents’ nuclear envelopes
  • Nucleoli reappear
  • Chromosomes become less condensed
  • Remaining spindle microtubules are depolymerized
  • Mitosis is complete!
  • Cytoplasm begins dividing
25
Q

Cytokinesis

A
  • Cytoplasm continues dividing
  • 2 daughter cells appear
  • Cleavage furrow forms, pinching the cell into 2
26
Q

centrosome

A

‘microtubule organizing center’
o region inside the cell that functions to organize the cell’s microtubules during the cell cycle
o Each contain 2 centrioles (which have no role in cell division)

27
Q

origin of replication

A

specific place on the chromosome where cell division begins in bacterial chromosome

28
Q

Binary fission

A
  • Bacterial cell division
    ‘division in half’
    o Cell division of prokaryotes and single-celled eukaryotes (bacteria and archaea)
    o However, in the eukaryotes this involves mitosis
    o Cell grows double its size and then divides into 2
29
Q

Binary fission (steps)

A

1) Chrom. replication occurs. Soon after, one copy of the origin moves toward the other end.
2) Replication continues. One copy of origin is now at end of each cell. Cell elongates
3) Replication finishes. PM pinches inward. New cell wall is created.
4) Result: 2 daughter cells.

30
Q

Plant Mitosis (idk if this needs to be a notecard)

A

• Prophase
o Chromosomes condense (are now visible!)
o Nucleoli disappear
o Mitotic spindle begins to form
o
• Prometaphase
o Chromosomes are MORE condensed
o Chromosomes each have 2 aligned sister chromatids
o Nuclear envelope fragments
• Metaphase
o Mitotic spindle formation is complete
o Chromosomes are attached to microtubules at their kinetochores
o Chrom. are lined up at metaphase plate
• Anaphase
o Chromatids of each chrom. have separated
o Daughter chrom. move toward end of cell as kinet. microtubules shorten
• Telophase
o Daughter nuclei form
o Cytokinesis has started

31
Q

cell cycle control system

A

cyclically operating set of molecules in the cell that trigger and coordinate key events in the cell cycle
o Subject to internal control and external adjustment
o Regulated at certain checkpoints

32
Q

checkpoint

A

control point in cell cycle where stop and go-ahead signals regulate cycle
• Three checkpoints: G1, G2, and M phases

33
Q

cyclin

A

protein with cyclically fluctuating concentration in the cell
o Level rises during S and G2 phases, and falls during M phase.

34
Q

(Cdks)

A
  • Cylcin-dependent kinases
  • kinases of cyclin
  • The activity of Cdk rises and falls with changes in concen. Of cyclin partner
  • Ex: MPF
35
Q

 MPF (maturation-promoting factor)

A

Cyclin-Cdk complex
• Has peaks of concen. which correspond with peaks of cyclin concen.
• It helps to think of this as the ‘M-phase promoting factor’ because it triggers cell’s passage into M phase (mitosis) past the G2 checkpoint
• First discovered in eggs

36
Q

S to G2 (Fluctuations of Kinases)

A

Synthesis of cyclin begins in late S phase and continues through G2.
• Cyclin is accumulating (it’s protected from degredation)

37
Q

G2 (Fluctuations of Kinases)

A

Cyclin combines with Cdk, producing MPF

• This checkpoint is passed when adequate MPF molecules accumulate (and mitosis begins!)

38
Q

M (Fluctuations of Kinases)

A

MPF promotes mitosis by phosphorylating different proteins.
• MPF acts as a kinase by activating other kinases
• MPF’s activity peaks during metaphase.
• During anaphase, the cyclin part of the MPF has degraded, terminating the M phase.

39
Q

G1 (Fluctuations of Kinases)

A
  • Degradation of cyclin continues

* CdK component of the MPF is recycled (this lasts through the S phase)

40
Q

G1 phase checkpoint

A

‘restriction point’- most important
• Where cell receives the signal to complete the G1, S, G1, and M phases and divide
• If cell does not receive the ‘go-ahead’ signal here, it may exit the cycle and switch into the G0 phase

41
Q

g0 phase

A

nondividing state

• where most cells of the body exist. Esp. muscle and nerve cells.

42
Q

growth factor

A

protein released by certain cells that stimulates other cells to divide
o Ex: Platelet-derived growth factor
• Growth factor made of platelets which is required for the division of fibroblasts
• The binding of PDGF molecules to PDGF receptors trigger signal transduction pathway allowing cells to pass G1 checkpoint and divide

43
Q

Density-dependent inhibition

A

phenomenon in which crowded cells stop dividing
o When two cells join together, the cell surface proteins bind together, sending a cell division-inhibiting signal (Signal cell to STOP dividing)
• This even occurs in the presence of growth factors.
• This is why cells will divide to form a layer, but if removed will grow to fill the gap

44
Q

anchorage dependence

A

when cells must be attached to an underlying surface in order to divide
o Signaled via pathways involving plasma membrane proteins which are linked to the cytoskeleton

45
Q

transformation

A

when cells acquire the ability to divide indefinitely

o On the other hand, all normal mammalian cells divide about 20-50 times before stopping and dying

46
Q

benign tumor

A

abnormal cells have too few genetic and cellular changes to survive at another site
o Can be removed surgically

47
Q

malignant tumor

A

abnormal cells whose genetic and cellular changes enable them to spread to new tissues and impair the functions of one or more organs = cancer
o Considered transformed cells
o May have unusual number of chromosomes
o May have altered metabolism
o May have lost attachment to neighboring cells or ECM
o Secrete molecule which attract blood vessels

48
Q

phosphorylation

A

adding a phosphate group to a molecule

49
Q

kinase

A

an enzyme that catalyzes the transfer of a phosphate group from ATP to a specified molecule

Biology 151 (Semester 1) (19 decks)

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