Cell Bicycle Flashcards

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1
Q

What are the four phases of the cell cycle?

A

M cycle, G1 phase, S Phase, and G2 Phase

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2
Q

Are yeast cells haploid or diploid?

A

Haploid

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3
Q

What is purifying selection?

A

A very important sequence that stays in nearly all organisms

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4
Q

What do cdc2 mutant yeast do? What is it caused by?

A

cdc2 mutant yeast replicate way too much and it is caused by losing the gene altogether

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5
Q

What happens when the cdc2 gene is restored in the mutants?

A

Restores the genotype

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6
Q

What happens when human cdc2 is put into mutant cdc2 yeast?

A

Genome is STILL restored (cus amino acids are basically the same)

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7
Q

At what rate is cyclin synthesized in the cell?

A

Constant, always being made

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8
Q

What regulates Cdk activity?

A

Cyclin

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9
Q

What triggers M-phase?

A

Cyclic protein synthesis

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10
Q

What triggers G1?

A

Cyclin degradation

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11
Q

How does ubiquitin mediated protein degradation work?

A

Ubiquitin grabs on to cyclin -> puts it in a proteasome -> leaves proteasome -> cyclin is degraded

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12
Q

What catalyzes ubiquitin?

A

Ubiquitin ligase

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13
Q

What triggers the end of M-phase/cause entry into G1?

A

Ubiquitylation and degradation of cyclin

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14
Q

What does Wee1 do to Cdk?

A

Phosphorylates it to inactivate it

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15
Q

What does cdc25 do to Cdk?

A

Removes inhibitory phosphates from Cdk to activate it

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16
Q

What happens when Cdk is active and attached to a cyclin?

A

Cell division

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17
Q

If a cell is not ready to continue to the next stage of the cell cycle, what is activated?

A

Wee1

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18
Q

If a cell IS ready to move onto the next step of the cell cycle what does it activate?

A

Cdc2

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19
Q

What holds two chromosomes together during pre S phase?

A

Cohesion proteins

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20
Q

What are the stages of mitosis in order?

A
  1. Prophase
  2. Prometaphase
  3. Metaphase
  4. Anaphase
  5. Telophase
  6. Cytokinesis
21
Q

What is the G2-M transition influenced by?

A

Cell size, DNA damage, and DNA replication

22
Q

What influences the Metaphase-Anaphase transition?

A

Chromosome attachments to spindle

23
Q

What influences the restriction point of the start? (Right before S phase)

A

Growth factors, nutrients, cell size, and DNA damage

24
Q

What happens in prophase?

A

Replicated chromosomes condense and the mitotic spindles begin to form along with the two centrosomes beginning to move towards the poles of the cell

25
Q

How do microtubules attach to chromosomes?

A

The kinetochores which are bounded to the chromosome on the centromere

26
Q

How do the centrosomes push away from each other?

A

Motors push the spindles in an anti parallel fashion

27
Q

What happens during prometaphase?

A

The nuclear envelope is broken down (in humans at least) and the chromosomes begin to attach to spindles

28
Q

What happens during metaphase?

A

Chromosomes are aligned in the middle of the cell

29
Q

What happens during anaphase?

A

Cohesions are removed from the chromosomes and finally begin to be pulled apart

30
Q

How do microtubules pull chromosomes apart?

A

The microtubules shrink

31
Q

What happens during telophase?

A

The two sets of daughter chromosomes reach the poles and the cell begins to pinch off from the contractile ring also the nuclear envelope starts reforming

32
Q

What pinches the contractile ring?

A

Actin

33
Q

During prometaphase, what does search and capture refer to?

A

The kinetochore of the chromosomes

34
Q

Where does the energy to pull the chromosome come from?

A

The energy released from the depolymerization of the microtubules

35
Q

What breaks down cohesions?

A

Separase (a protease)

36
Q

What inhibits separase?

A

Securin

37
Q

What frees separase from securin?

A

APC

38
Q

What is APC?

A

Anaphase promoting complex (a ubiquitin ligase that targets mitotic cyclin ands securin for degredation)

39
Q

For the metaphase-anaphase transition, what must happen before APC can activate?

A

Spindles must be attached to spindle

40
Q

What are the main differences between meiosis and mitosis?

A
  • in meiosis, the duplicates homologous are paired
  • meiosis results in 4 haploid daughter cells, mitosis results in two diploid daughters
41
Q

What holds sister chromatids together? (Same chromosome just duplicated)

A

Cohesions

42
Q

What holds homologous chromosomes together?

A

Chiasmata (during meiosis 1)

43
Q

When does recombination happen?

A

Before the chromosomes line up (metaphase 1)

44
Q

When do homologous chromosomes segregate?

A

Anaphase 1

45
Q

When do alleles separate?

A

Meiosis 2

46
Q

What are the 3 stages of meiosis?

A

Meotic S phase -> Meiosis 1 -> Meiosis 2

47
Q

What happens during anaphase 1 in meiosis?

A

Cohesions are removes from the chromosome arms and homologous pairs are pulled apart

Cohesions are centromeres are SAFE, sisters stick together

48
Q

What happens during anaphase 2 in meiosis?

A

Cohesions are removes at centromeres, sisters are pulled apart