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Biology 108 Test #2 > Mitosis > Flashcards

Mitosis Flashcards

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1
Q

What is the cell cycle known as?

A

Lifetime of cell from formation until division.

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2
Q

What distinguishes living matter form nonliving matter?

A

The ability to reproduce or undergo division.

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3
Q

When a unicellular organism divides what does it produce?

A

A reproduction of the entire organism.

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4
Q

What is does a daughter cell of mitosis look like in relation to its parent cell?

A

It is a CLONE. Identical genetic information, DNA.

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5
Q

What are some things that a multicellular organism depends on cell division for?

A

Development from a fertilized cell

Growth

Repair

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6
Q

What is the type of cell division that produces nonidentical daughter cells (gametes)?

A

Meiosis

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7
Q

What does a cells genome consist of?

A

The DNA within a cells nucleus.

Does NOT include DNA located in mitochondria

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8
Q

Where would we tend to see a genome that consists of one DNA molecule and a genome that consists of multiple DNA molecules?

A

Single - Prokaryote (circular)

Multiple or Single - Eukaryote (linear)

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9
Q

What are DNA molecules packaged into?

A

Chromosomes - also have proteins

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10
Q

What is chromatin?

A

this is a complex of DNA molecules and proteins that condense during cell division into chromosomes

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11
Q

What is the difference between somatic cells and gametes?

A

Somatic cells have two sets of chromosomes

Gametes have half as many chromosomes as somatic cells

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12
Q

What is the division of molecular mass of protein and DNA in a chromosome?

A

50/50

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13
Q

What happens to DNA as the cell prepares for cell division?

A

It is replicated and chromosomes condense

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14
Q

What does each duplicated chromosome consist of? are there now 2 chromosomes??

A

Two sister chromatids.

NOOOOOO, still 1 chromosome

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15
Q

What is the centromere?

A

the narrow “waist” located towards the middle of the chromatid where the two sister chromatids are most closely attached

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16
Q

When is a duplicated chromosome with 2 sister chromatids considered 2 separate chromosomes?

A

When they separate during cell division.

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17
Q

How many centromeres in a duplicated chromosome?

A

2

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18
Q

What are the two phases of eukaryotic cell division?

A

Mitosis - division of nucleus

Cytokinesis - division of cytoplasm.

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19
Q

What does the cell cycle consist of?

A

Mitotic (M) phase - mitosis and cytokinesis

Interphase - cell growth and copying of chromosomes to prepare for division

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20
Q

What are the subphases of interphase?

A

G1 (first gap) - growth, preparing for DNA duplication

S (synthesis) - DNA being duplicated

G2 (second gap) - Growth, preparing for mitosis

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21
Q

What are the subphases of the M (mitosis) phase?

A

Prophase

Prometaphase

Metaphase

Anaphase

Telophase (cytokinesis well underway during this late telophase)

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22
Q

What is happening during G2 of interphase

Is there a visible nucleolus? Nuclear envelope?

A

Centrosome is duplicated - EACH HAVE CENTRIOLE PAIR, this is where the assembly and organization of microtubules begin

Visible nuceolus and nuclear envelope.

Chromosomes beginning to condense

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23
Q

Describe prophase.

A

Centrosomes begin moving to opposite poles of the cell but have not reached them yet

Nuclear membrane disintegrating but is still visible

Nucleolus disappeared

Chromosomes visibly condensed and separated.

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24
Q

Describe Prometaphase.

A

Centrosomes reached opposite poles of the cell

Spindle apparatus made of microtubules have begun attaching to chromosomes at their KINETOCHORE located at centromere of chromosome

Nuclear envelope completely disappeared

Chromsomes even more condensed at this point

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25
Q

Does each sister chromatid become attached to a spindle fiber from opposite poles?

A

YES

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26
Q

Describe Metaphase.

A

Chromosomes lined at metaphase plate

centrosomes at opposite poles still

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27
Q

Describe anaphase.

A

The “glue” that holds sister chromatids together is broken down and they are now separated and pulled to opposite poles of the cell

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28
Q

Describe telophase and cytokinesis.

A

Cleavage furrow present

Nuclear envelope forms

Chromosomes decondense

Nucleolus begins to form

29
Q

What is the mitotic spindle?

A

An apparatus of microtubules that control chromosome movement during mitosis.

30
Q

What is an aster?

A

A radial array of short microtubules that extends from each centrosome.

31
Q

What makes up the spindle?

A

Centrosome

Spindle mircotubules

Aster

32
Q

What are the two ways that a chromosome can be pulled towards a centrosome? How did scientists figure this out?

A

It can either travel along the microtubule towards the pole or be reeled in like a fish. Both involve the microtubule depolymerizing

Scientists marked a spot in the middle of the microtubules and assessed which side in relation to the mark began to depolymerize and shorten.

33
Q

What is a nonkinetochore microtubule and its function?

A

These dont attach to a kinetochore but attach to one another and push against each other to elongate the cell.

34
Q

What is the main thing that is happening in telophase?

A

genetically identical daughter nucleus is forming at opposite ends of the cell.

35
Q

What is the process of cytokinesis called in regards to an animal cell? Describe the process.

A

CLEAVAGE - cleavage furrow is formed by actin filaments that line up in middle and contract until the cell is essentially cut in two.

36
Q

How does cytokinesis differ in regards to a plant cell? Describe the process.

A

Plant cells form a cell plate in the middle. (cleavage plate)

Vesicles congregate at middle and eventually combine and form a new cell wall.

37
Q

Other than a cell plate during cytokinesis, what is another difference in plant cell mitosis discussed in class?

A

No centrioles as found in animal cells

38
Q

How do Prokaryotes (bacteria and archaea) reproduce? is this a form of mitosis?

A

Binary fission

NO

39
Q

Do prokaryotes undergo mitosis?

A

NO, THEY LACK A NUCLEUS

40
Q

Where does the chromosome begin to replicate in a prokaryote during binary fission?

A

At the origin of replication to make 2 origins.

41
Q

In binary fission, what happens after the DNA origin is replicated

A

One origin will move to opposite ends of the cell. DNA replication continues at the origin and the cell is also elongating.

42
Q

During binary fission, once each origin is at the opposite end of the cell and the entire chromosome has been replicated, what happens next?

A

The cell will divide in a way very similar to cytokinesis.

43
Q

Since prokaryotes evolved before eukaryotes, its likely that what cell division process evolved from what?

A

mitosis evolved from binary fission

44
Q

Are there some protists that exhibit cell division that seems to be intermediate between mitosis and binary fission?

A

YES

45
Q

What types of organisms undergo binary fission?

A

prokaryotes!

46
Q

What are some intermediate cell division characteristics exhibited by dinoflagellates (eukaryote)?

A

Nuclear envelope remains intact while MICROTUBULES penetrate through the nuclear envelop to the opposite pole to provide strucure.

Chromosomes replicated and stick to inside of nuclear envelope and are pulled apart as nucleus expands and gets ready to divide.

47
Q

What are some intermediate cell division characteristics exhibited by diatoms and yeast (eukaryote)?

A

nuclear envelope remains intact, microtubules form inside the nucleus and attach at kinetochores of chromatids and separate them.

48
Q

Does the frequency of cell division vary with the type of cell?

A

YES

49
Q

How is the division of cells regulated?

A

At the molecular level using chemical signals.

50
Q

What were some experiments done to prove that chemical signals are what drive mitosis?

A

Cultured cells at different stages of the cell cycle were fused together and the cell that was at an earlier stage in the cell cycle jumped to the later stage the fused cell was in, whether or not they did all steps required before that stage. This was due to the chemical signals being transferred to the other cell.

EXAMPLE:
S fused with G1 - G1 cell immediately entered S phase.

M fused with G1 - G1 immediately began mitosis without even replicating their DNA.

51
Q

What is the cell cycle control system controlled by?

A

Internal and External signals

Described as a clock.

Stops at checkpoints until go-ahead signal is received.

52
Q

What is the most important checkpoint for most cells?

A

The G1 checkpoint:

  • usually if receiving the go-ahead at this checkpoint the cell will complete the rest of the cycle and divide (S, G2, and M)
  • If no go-ahead signal received, the cell will go into G0 phase in which it exits the cell cycle into a nondividing state.
53
Q

What is a crucial purpose for the cycle checkpoints?

A

To prevent mutated or cancerous cells from dividing.

54
Q

What are the two regulatory proteins involved in the cell cycle?

A

Cyclins -

Cyclin-dependent kinases - phosphorylates to either activate or deactivate (only active with cyclin present)

55
Q

What is the function of MPF (maturation-promoting factor)

A

MASTER PHOSPHORYLATOR:

CYCLIN-CDK COMPLEX THAT TRIGGERS A CELLS PASSAGE PAST G2 CHECKPOINT INTO THE M PHASE

56
Q

Look at the chart that correlated protein kinase activity with number of dividing cells. what were the correlations.

A

A rise in kinase activity precedes a rise in dividing cells as well as a drop in kinase activity precedes a drop in dividing cells

57
Q

There is a graph in the powerpoint that shows cyclin concentration vs. MPF activity. what was the main point shown by this?

A

MPF activity is dependent on cyclin concentration

58
Q

What happens to the cyclin component of MPF in anaphase? What does this cause?

A

The cyclin component is degraded.

This terminates the M phase and starts the G1 phase.

59
Q

What are some examples of internal signals that regulate the cell cycle?

A

At the M checkpoint - the separation of sister chromatids (anaphase) will not occur until all chromosomes are properly attached to the spindle at the metaphase plate.

60
Q

What is an example of an external signal regulating the in cell cycle?

A

Growth factors - proteins released by certain cells that stimulate other cells to divide. Like platelet-derived growth factor (PDGF) stimulates the division of human fibroblasts.

These cells rely on PDGF to divide, they would not divide without it.

61
Q

What is density-dependent division and what is anchorage dependent division?

A

Density dependent - crowded cells stop dividing

Anchorage dependent division - they must be anchored to a substratum before they divide.

62
Q

Do cancer cells exhibit density dependent inhibition or anchorage dependence?

A

NO

63
Q

Cancer cells dont respond to the bodies normal control mechanisms of cell division. What are some examples of how cancer cells may not need external growth factors to grow and divide?

A

May make their own growth factor

May convey a growth factors signal without it being present

may have an abnormal cycle control mechanism

64
Q

What is the process of transformation?

A

When a normal cell is converted to a cancerous cell.

65
Q

What do cancer cells do?

A

Form tumors - masses of abnormal cells within normal tissue.

66
Q

What is a benign tumor?

A

A tumor that remains at its original site of origin.

67
Q

What is a malignant tumor?

A

These tumors invade surrounding tissues and can metastasize

68
Q

What is metastasis?

A

cancer cells get in bloodstream or lymph nodes and enter other parts of body to form secondary tumors.

69
Q

Describe the breast cancer depiction of a cancer cell from when the cancer cells begin to replicate.

A
  1. Tumor grows from a single replicating cancer cell.
  2. Cancer invades the neighboring tissue.
  3. Cancer spreads through lymph and blood vessels to other parts of the body.
  4. Some cancer cells in lymph and blood metastasize to other parts of the body.

Biology 108 Test #2 (5 decks)

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