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BI110 > Chapter 7 - Cell Cycles > Flashcards

Chapter 7 - Cell Cycles Flashcards

(53 cards)

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1
Q

how do cells originate?

A

from pre-existing cells through process of cell division and replication

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2
Q

why is cell growth and division important?

A
  • increasing population size
  • growing new tissues
  • asexual reproduction
  • replacement of lost cells and damaged cells (wound repair)
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3
Q

what is binary fission?

A
  • reproduction when a single, original parent cell splits into two daughter cells
  • an organism duplicates its DNA and then divides into two parts via cytokinesis, and each new organisms receives a copy of the DNA
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4
Q

what process do prokaryotic cell use to divide?

A

binary fission

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5
Q

what are the steps to binary fission?

A

1.) replication begins at the origin (ori) at the middle of the cell where DNA enzymes are located
2.) the ori is duplicated, and the two origins migrate to either end of the cell (left and right)
3.) division of the cytoplasm occurs to separate into two daughter cells by the inward growth of the plasma membrane/cell wall and cytoskeletal proteins

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6
Q

what is the bacterial growth curve?

A

represents the number of live cells in a bacterial population over a period of time.

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7
Q

what are the phases of the bacterial growth curve?

A

1.) lag phase
2.) exponential phase
3.) stationary phase
4.) death phase

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8
Q

what do the phases of the bacterial growth curve represent?

A
  • The initial phase is the lag phase where bacteria are metabolically active but not dividing.
  • The exponential or log phase is a time of exponential growth.
  • In the stationary phase, growth reaches a plateau as the number of dying cells equals the number of dividing cells.
  • The death phase is characterized by an exponential decrease in the number of living cells.
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9
Q

how are mitosis and binary fission related?

A

it is believed that binary fission is the ancestral cell division process in which mitosis evolved from

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10
Q

where is DNA and genome located in prokaryotic and eukaryotic cells?

A

prokaryotes:
genome = one small, circular chromosome
DNA = in cytoplasm

eukaryotes:
genome = multiple, large, linear chromosomes
DNA = in nucleus

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11
Q

what is the cell cycle?

A

a period of growth followed by nuclear division and cytokinesis

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12
Q

what is mitosis?

A
  • divides replicated DNA equally and precisely
  • makes sure two cells resulting from division have same genetic info as the parent cell
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13
Q

what is the significance of mitosis?

A
  • used for the growth and maintenance of body mass in multicellular eukaryotes
  • reproduction of many single- celled eukaryotes
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14
Q

how is DNA divided in eukaryotic cells?

A
  • into individual, linear chromosomes located in the cell nucleus
  • chromosomes (DNA) are genetic units that are divided by mitosis
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15
Q

ploidy

A

the number of sets of chromosomes in a cell or an organism

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16
Q

haploid

A

a cell with one complete set of chromosomes (n =23)

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17
Q

diploid

A

a cell with two complete sets of chromosomes (2n = 46)

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18
Q

sister chromatids

A

the two identical molecules that are created when each chromosome’s DNA is replicated

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19
Q

what is chromosome segregation?

A

the equal distribution of daughter chromosomes (DNA) to each of the two cells resulting from cell division

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20
Q

what is interphase?

A

is the first stage of the cell cycle and begins immediately after mitosis (and cytokinesis) and continues until the beginning of the next mitosis

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21
Q

what are the sub-phases of interphase?

A

1.) G1 phase
2.) S phase
3.) G2 phase

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22
Q

what is the G1 phase of interphase?

Study These Flashcards
A
  • initial “gap” phase
  • the period of growth before the DNA replicates
  • cell carries out functions
23
Q

what is the S phase of interphase?

Study These Flashcards
A
  • DNA replication and chromosome duplication occurs (results in two sister chromatids)
24
Q

what is the G2 phase of interphase?

Study These Flashcards
A
  • the second “gap” in the cell cycle
  • cell growth continues
  • prepares for mitosis and cytokinesis
25
what are the 5 stages of mitosis?
1.) prophase 2.) prometaphase 3.) metaphase 4.) anaphase 5.) telophase
26
what happens in prophase?
- chromosomes condense into compact, rod-like structures - spindles form in the cytoplasm
27
what happens in prometaphase?
- nuclear envelope disappears - spindle enters the former nuclear area - microtubules from opposite spindle pores attach to two kinetochores of each chromosomes
28
what happens in metaphase?
- the spindle is fully formed - chromosomes align at the spindle midpoint (is moved there by the spindle microtubules)
29
what happens in anaphase?
- spindles separate sister chromatids and moves them to opposite spindle poles - chromosome segregation is complete
30
what happens in telophase?
- chromosomes decondense (unfold) and return to extended state typical of interphase - new nuclear envelope forms around chromosomes
31
what is cytokinesis?
the completion of cell division by dividing the cytoplasm between daughter cells
32
how does cytokinesis by furrowing work in animal cells?
1.) band of microfilaments form on the inside of the plasma membrane, creating a belt across it 2.) microfilaments slide together and tighten, constricting the cell and forming a furrow (indent) in the plasma membrane 3.) gradually separates cytoplasm in two parts
33
how does cytokinesis work in plant cells?
1.) cell wall material is deposited along the plane of a former spindle midpoint 2.) deposition continues until they fuse together and a new wall (cell plate) separates daughter cells
34
what are centrosomes?
contain a pair of centrioles that divide and move apart (animal cells only)
35
what are microtubules?
radiate outwards from centrosomes to from the spindle
36
do plant cells contain centrosomes?
no, but they still form spindles comprised of microtubules
37
what kinetochore microtubules?
connect chromosomes to spindle poles
38
what are nonkinetochore microtubules?
- extend between spindle without connecting to chromosomes - at spindle midpoint, microtubules from one pole overlap with those from another pole
39
what are the movements of microtubules?
kinetochore = lessens distance from chromosomes to the poles nonkinetochore = pushes poles further apart and increases total length of the spindle
40
what are the significance of checkpoints in the cell cycle?
created by important internal controls to ensure one stage is complete before cycle proceeds to next stage = accurate cell division
41
how is the cell cycle controlled?
by protein complexes between cyclin and cyclin-dependent kinases (CDK's)
42
how many different cyclins are there?
4 = cyclin D, E, A, B (G1, S, G2, Mitosis)
43
what are CDK's?
- cyclin dependent kinases - protein kinases which phosphorylate and regulate the activity of target proteins - only active when bound to the proper cyclin
44
how do cyclins control the cell cycle?
- CDK's bind to the appropriate cyclin in order to be activated and progress through the cell cycle - if a different cyclin is detected, the cell cycle wont continue - CDK combinations regulate cell cycle transitions at different "checkpoints"
45
what are the internal controls that regulate the cell cycle?
- cyclins and cyclin dependent kinase complexes - they create checkpoints that ensure the reactions of one stage are complete or conditions or correct before proceeding to the next stage
46
what are the external controls that regulate the cell cycle?
- based on the surface receptors that receive external signals (ex: hormones, growth/death factors) - binding of signals trigger specific internal reactions that slow, speed or stop cell division via signal transduction pathways that can activate/inactivate cyclin-cdk complexes
47
what is MPF (mitosis promoting factor)?
a cyclin-cdk complex that participates in enzyme activation, nuclear envelope breakdown, and chromosome condensation
48
what is contact inhibition?
the process that prevents cells from growing if they become too crowded
49
how does contact inhibition work in normal cells?
- cell density is communicated by cell to cell interactions through cell surface receptors - if cells are removed from the culture surface, cells will divide to fill the gap but stop once it has been filled
50
how does contact inhibition work in transformed cells?
- it is lost in some cancer cells, which may produce excess growth factors or have failures in cell cycle regulation - uncontrolled cell growth
51
cell senescence
loss of proliferative (cant divide) ability of time as a result of DNA damage and telomere shortening
52
how is cancer caused?
- cells divide continuously and controllably forming a rapidly growing mass of cells - cancer cells typically have several mutations in genes that code for cyclin-cdk cell cycle regulation system, surface receptors or components of signal transduction pathways that regulate cyclin-cdks
53
what is apoptosis?
programmed cell death resulting from internal or external signals

BI110 (3 decks)

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