T4M1 Flashcards

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1
Q

The ability for a pre-existing cell to give rise to
another cell is due

A

the regulated process of cell division

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2
Q

prokaryotic cells, cell division is also

A

reproduction since the division of one prokaryotic cell will give rise to a new organism
(made up of one cell)

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3
Q

Prokaryotic reproduction

A

All of the essential elements necessary to reproduce cells are found in the prokaryotic cell. These cells are capable of making exact copies of their genomes and then segregating one copy of each genome to each of two daughter cells

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4
Q

The process of cell division in prokaryotes requires that

A

identical genetic material is distributed amongst daughter cells

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5
Q

In prokaryotes, the process of cell division is a form of

A

asexual reproduction that is often referred to
as binary fission

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6
Q

The process of cell division in prokaryotes is initiated when

A

the DNA of the bacterial chromosome is attached by proteins to the inside of the plasma membrane

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7
Q

DNA replication can then begin along

A

an origin of replication region of the bacterial chromosome

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8
Q

As the chromosome continues to replicate, the
cell begins to

A

elongate, and the newly synthesized DNA is also anchored to the plasma membrane

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9
Q

As binary fission progresses, the cell continues to

A

elongate until the two DNA attachment sites are at opposite ends of the elongated cell

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10
Q

When DNA replication is complete and the bacterium is approximately double its original size, the bacterial cell begins to

A

constrict along the midpoint of the cell along with synthesis od a new cell membrane and wall

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11
Q

Cell division in eukaryotes

A

mitosis

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12
Q

In eukaryotic organisms, cell division allows for a

A

unicellular fertilized egg to develop into a
complex multicellular organism

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13
Q

Early embryos contain

A

stem cells

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14
Q

Stem cells

A

unspecialized cells that can both reproduce indefinitely and under appropriate conditions, are able to differentiate into specialized cells of one or more type

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15
Q

Activation of satellite stem cells leads to

A

proliferation, differentiation and fusion of muscle precursor cells: myoblasts

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16
Q

Distinctions between prokaryotic and eukaryotic cell divisions is largely due to

A

eukaryotic DNA is larger, is organized
into linear chromosomes and is highly condensed into the nucleus of the cell

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17
Q

The process of cell division in eukaryotes requires more

A

regulated control as part of a larger cell cycle

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18
Q

Standard eukaryotic cell cycle two stages

A

interphase, M phase

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19
Q

interphase includes

A

the S phase (where DNA synthesis
occurs), and 2 gap growth phases G1 and G2

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20
Q

M phase is where

A

mitosis and cytokinesis occurs

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21
Q

With each mitotic cell division, the linear
chromosomes of eukaryotes must be

A

replicated and then separated into daughter cells

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22
Q

What stage do cells make preparations for cell division which include the replication of DNA in the nucleus, and an overall increase in cell size

A

interphase

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23
Q

Replication of DNA will occur in what phase?

A

S (or synthesis) phase

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24
Q

What phases prepare the cell for DNA synthesis and mitosis?

A

G1 and G2 phases

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25
Q

Walther Flemming in 1882 discovery

A

the distinct stages of mitosis could be staged based on chromosomal position and features

26
Q

Walther Flemming analysis

A

developing salamander embryos that he had stained to be able to visualize the chromosomes of the dividing cells

27
Q

Mitosis 5 stages

A
  1. prophase
  2. prometaphase
  3. metaphase
  4. anaphase
  5. telophase
28
Q

During most of interphase, each chromosome is
in the form of

A

a long, and thin chromatin fiber

29
Q

Prior to mitosis

A

exact copies of every chromosome are created in S phase

30
Q

Sister chromatids

A

when a chromosome is duplicated into two
identical copies

31
Q

Human chromosome how many pairs

A

23 distinct chromosome pairs - where 22
are homologous chromosomes (one maternal
and one paternal in origin) and 1 pair are our sex chromosomes

32
Q

What phase are chromosomes compacted?

A

M-phase

33
Q

The beginning of the M-stage of the cell cycle
follows up on the end of

A

interphase G2 phase

34
Q

During interphase, specific chromosomes

A

cannot be identified since they are organized into the long chromatin fibers

35
Q

As a cell transitions from G2 to the M-phase, the
duplicated chromosomes

A

begin to condense, and the individual chromosomes become visible even with a light microscope

36
Q

What happens during prophase?

A
  • each chromosome will appear as identical sister chromatids that are joined at their centromeres.
  • at the same time, duplicated cellular microtubule organizing centres referred to as the centrosomes, begin to radiate long microtubules, forming a mitotic spindle.
  • the centrosomes will become positioned at opposite poles of the cell, and the mitotic spindle will become crucial for separating the chromosomes into the two daughter cells.
37
Q

What happens during prometaphase?

A
  • the fragmentation of the nuclear envelope
  • microtubules that are extending from each
    centrosome as part of the mitotic spindle are able to attach to specialized regions on the
    centromeres of the chromosomes (kinetochores)
38
Q

Kinetochores

A

specialized protein structures that associate with each one of the two sister chromatids on either side of the centromere

39
Q

Kinetochore microtubules are essential to

A

help pull the chromosomes to the poles of the cell during mitosis

40
Q

polar microtubules

A

will interact with each other and help push the poles of the cell away from each other during mitosis

41
Q

What happens during metaphase

A

alignment of chromosomes at the center of a cell at metaphase plate

42
Q

What happens during anaphase?

A
  • kinetochore microtubules begin to shorten
  • sister chromatids separate into
    individual chromosomes that are pulled towards the opposite spindle poles of the cell
  • polar microtubules push against each other and help elongate the cell
  • the two ends of the cell will have equivalent and complete sets of chromosomes
43
Q

What happens in telophase?

A
  • two new daughter nuclei form in the cell
  • nuclear envelope reforms around the chromosomes at the opposite poles of the
    dividing cell
  • chromosomes begin to decondense and spindle microtubules are depolymerized
44
Q

What marks the end of mitosis

A

The division of one nucleus into two genetically
identical nuclei

45
Q

Process of mitosis must be followed up by

A

the division of the cell into two individual cells

46
Q

Cytokinesis

A

division of the cytoplasm and therefore of the cell

47
Q

In animals cytokinesis begins with

A

the formation of a contractile ring made up of motor proteins that contract bundles of actin fibers along the midline of the cell

48
Q

The formation of a contractile ring leads to

A

the formation of a defined cleavage furrow which separates the cell into two distinct and separate daughter cells

49
Q

Cytokinesis in plant cells

A

lay down a newly developed cell wall along a cell plate region in the middle of the dividing cell. Once the forming cell wall fuses with the original cell wall, cytokinesis is complete

50
Q

Tim Hunt 1980’s

A

measure the protein level changes of dividing sea urchin embryo

51
Q

mitosis promoting factor consists of

A

a cyclin protein and a cyclin-dependent kinase (or CDK) protein and that together they control progression of the cell cycle

52
Q

Kinases

A

enzymes that activate or inactivate other proteins by phosphorylating key amino
acids on the target proteins

53
Q

cyclin-cyclin dependent kinase complex

A

trigger the multitude of changes that occur during the various cell cycle events, specifically by phosphorylation of target proteins that promote cell division

54
Q

G1/S cyclin-CDK complex is needed for

A

the transition from the G1 to S phase and helps to prepare the cell for DNA replication (such as increasing the expression of histone proteins)

55
Q

S-cyclin-CDK complex

A

initiate DNA synthesis and the M cyclin-
CDK complex initiates the process of mitosis.

  • This is facilitated for example by phosphorylation of key structural proteins that are needed for nuclear membrane breakdown and to regulate the assembly of microtubules in the mitotic spindles
56
Q

The three major checkpoints of the cell cycle consist of

A

a DNA damage checkpoint at the end of G1 phase, a DNA replication checkpoint at the end of the G2 phase, and a spindle assembly checkpoint before anaphase during mitosis

57
Q

p53

A

a protein that can inhibit the cell cycle when turned on, present in low levels in the nucleus, produces CDK inhibitor protein bind to and
block the activity of the G1-S cyclin-CDK complex pauses cycle in G1 phase

58
Q

proteins that are associated with the spindle assembly checkpoint are able to

A

monitor the degree to which the sister chromatids are attached to microtubules of the mitotic spindle at their kinetochore regions

59
Q

unattached kinetochores create a

A

“wait” signal which leads to the recruitment of
spindle-assembly checkpoint proteins

60
Q

spindle-assembly checkpoint proteins

A

proteins activated by a lack of tension in the
centromere area, and only allow for the
progression of metaphase and entry into
anaphase when each sister chromatid is attached to a kinetochore microtubule

61
Q

spindle checkpoint proteins are removed from

A

the centromere region, and separase, a
specialized enzyme, is able to break sister
chromatid attachments.