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Biology 107 > LECTURE 15 > Flashcards

LECTURE 15 Flashcards

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1
Q

What do the signals that control cell division for eukaryotes related to?

A

The function of the entire organism, not the individual cell.

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2
Q

Do eukaryotes of multiple origins and if so, why?

A

Yes, because their chromosomes are very long

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3
Q

Why is eukaryotes DNA segregation more complicates then prokaryotes

A
  • nuclear envelope
  • multiple chromosomes
  • each chromosome can be very long
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4
Q

Replicated DNA molecules becomes very ___________ in the __________ before they segregate in eukaryotes

A

Condensed Nucleus

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5
Q

Chromatin

A

A complex of DNA and proteins that are the building materials for chromosomes

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6
Q

Sister chromatids

A

Two copies of replicated DNA that are connected to each other

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7
Q

Centromere

A

A physical construction of the duplicated chromosome. Sister chromatids attach at this site.

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8
Q

Eukaryotes cytokinesis

A
  • division of cytoplasm
  • final stage of cell reproduction
  • different in plant and animals cells
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9
Q

Do the number of chrome men’s correlate with the complexity of the organism ?

A

NO

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10
Q

Each chromosomes form each parent are closely matched in :

A
  • physical appearance

- genetic info content (NOT identical)

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11
Q

All parts of interphase

A 
M = mitotic phase 
G1 = Gap phase 
S = DNA synthesis phase 
G2 = Gap 2 phase
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12
Q

Interphase

A
  • chromosomes present but NOT visible

- metabolic activity and growth occur, control decisions to grow.

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13
Q

G1 phase

A

Prepares the cell for DNA replication by growing in size.

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14
Q

Start of S phase

A

DNA replication when the two strands of helix unwind (starting at the origin)

  • each serves as a template for synthesis of a new strand

REPLICATION OF DNA

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15
Q

End of S phase

A

Each chromosome (there are 2) consists of one old strand and one new strand

  • chromatids are tight to associated at Centro mere region
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16
Q

G2 phase

A

cell prepares for chromes segregation and cell division

  • centrioles duplicate (new one (daughter centriole, d) grows out of the older centriole (mother centriole, m))
  • Nucleolus visible
  • chromes duplicated but NOT condensed
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17
Q

When do centriole duplicate

A

G2

18
Q

Prophase

A

The two centrosomes gets in to separate.

  • nucleoli disappear
  • chromatin fibbers becomes more condensed and visible
  • sister chromatids visible
  • centrosome visible
19
Q

Why do the centrosomes separate in prophase

A

because of microtubule growth and motor proteins pushing against opposite microtubules

20
Q

Prometaphase

A

Nuclear envelope begins to breakdown.

  • kinetochores grab onto microtubules and holds on the end of microtubules
  • microtubules grow and shrink
21
Q

How does the nuclear envelope breakdown in prometaphase ?

A

Liam is disassemble, and membrane forms small vesicles that remain around the chromosomes

22
Q

What does the breakdown fo the nuclear envelope during prometaphase allow?

A

Allows microtubules to grow into the area and make contact with kinetochores

23
Q

Kinetochores

A

Each chromatid has ONE kinetochore; the pair face in the opposites directions. The kinetochores captures microtubules and is required for proper chromosome congregation and separation of sister chromatids.

24
Q

What are kinetochores made of ?

A

Larger structure made of many types of proteins.

25
Q

Where doe kinetchore protujens assemble on ?

A

They assemble on the centromeric DNA

26
Q

What holds chromatids together

A

Cohesins

27
Q

Cohesins

A

Special protein complexes that hold chromatids together

28
Q

Do cohesins remain intact during anaphase?

A

YES

29
Q

When all chromosomes are at the met phase splats and properly attached to microtubules, a signal is sent that results in…

A

A part of cohesins getting destines by protease called separase. This opens the ring, along the sister chromatids to separate.

30
Q

Before anaphase a protector protein (called _____) prevents the _________ of cohesins

A

Securin. Destruction

31
Q

At the start of anaphase, securin gets destroyed by a protein degration machine called the

A

Anaphase-promoting complex

Or

APC

32
Q

Loss of securin results in the

A

Cohesin ring opening up or breaking apart

33
Q

Anaphase

A
  • shortest stage
  • begins when cohesin protests are cleaved
  • tensions builds due to kinetochore microtubules pulling equally in opposite directions
  • this tensions released and chromatids move rapidly apart, with kinetochore leading away
34
Q

Mitotic chromatid segregation can occur by two different events:

A

1) short eating the distance between poles and chromatids (anaphase A)
2) movement of spindle poles (chromosomes) apart (anaphase B)

Cell may use either or both of these methods

35
Q

Telophase

A
  • Two daughter nuclei form in cell
  • nuclear envelope start to reform
  • chromosomes start to de-condense
  • spindle microtubules depolymerize
  • nucleoli reappear
  • results in 2 identical daughter cells
36
Q

Plant mitotic spindles

A
  • sue chromatin (not centrosomes) to uncleared microtubules

- spindle assembles in an “inside-out” fashion

37
Q

Some animal cells and many female meiotic spindles assemble

A

Without centrioles

38
Q

Mitotic spindles in prometaphase

A

Microtubules start to form around the chromatin as soon as nuclear envelop starts to break down

39
Q

Mitotic spindles in metaphase

A

Kinetochore-microtubules form alongside non-kinetochore microtubules (bipolar spindles forms)

40
Q

Mitotic spindles in anaphase and telophase

A

Microtubules become cross linked (microtubule motor proteins involved) - this proved stable structure for chromatid segregation

Biology 107 (21 decks)

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