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Bio 1201 lsu > Chapter 12 - Mitosis > Flashcards

Chapter 12 - Mitosis Flashcards

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Biology 101 flashcards
1
Q

What’s the basic timeline of a cell cycle?

A

From cell formation to its own division into daughter cells

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2
Q

Do all cells perform mitosis?

A

No, the exceptions are gametes or sex cells. These do not produce cells with identical genetic information.

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3
Q

Are there different types of cell division?

A

Yes, mitosis and meiosis

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4
Q

What happens to a cell in mitosis?

A

A cell divides into two identical daughter cells in which the genetic identity (DNA) is the exact same.

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5
Q

what are gametes?

A

Sex cells. There are two types, males have sperm cells and females have egg cells

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6
Q

What main functions does cell division function in?

A

Reproduction
Growth and development
Tissue Renewal

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7
Q

What is a genome?

A

A term for all of the DNA in a cell WITHOUT proteins wrapped around them

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8
Q

What are chromosomes?

A

There are individual DNA molecules packed together with proteins called chromosomes.

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9
Q

what is chromatin?

A

Chromatin is the term for ALL OF DNA WITH PROTEIN that condenses during division

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10
Q

What are cells that aren’t gametes reffered to as?

A

They are reffered to as somatic cells or nonreproductive cells. They comprise 99% of the entire body’s cells.

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11
Q

How many sets of chromosomes do somatic cells have and how many sets of chromosomes do gametes have?

A

Somatic cells - two sets
Gametes - half set of chromosomes

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12
Q

Make a relationship between types of cells and the type of cell division they undergo

A

Somatic - Mitosis
Gamete - Meiosis

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13
Q

What is it called when two chromosomes are attached to each other and are identical?

A

Sister chromatids

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14
Q

Why is the chromosome pinched in the middle of its body?

A

The pinched region is called the centromere, it is the region that gets attached to the microtubule during mitosis.

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15
Q

Are chromosomes usually with their sister chromatids?

A

No, they duplicate before cell division occurs so that the duplicated version of chromosome can enter the new cell.

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16
Q

Divide the cell cycle into its major parts

A

There are two major phases - Interphase and Mitosis

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17
Q

What occurs in Interphase and what occurs in mitosis ? (brief summary)

A

During interphase, the cell is getting ready to divide and duplicates DNA

During mitosis, the actual cell division physically occurs

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18
Q

Which major phase does the cell spend most of its time in during the cell cycle?

A

Interphase - 90% of it

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19
Q

What are the three major subphases of Interphase in mitosis?

A

G1 S1 G2

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20
Q

What are the subphases of mitosis

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

What are the visual cues of prophase occuring?

A

When DNA condenses tightly into chromosomes and the microtubules start to form a mitotic spindle at one side of cell.

22
Q

What are the visual cues of prometaphase occuring?

A

When microtubules form really long mitotic spindles.

The centrosomes are positioned at the opposite sides of the cell.

The centromeres on chromosomes start to get attached to mitotic spindle.

The nuclear envelope starts to dissolve into the cytosol

23
Q

What are the visual cues that metaphase is occuring?

A

All the chromosomes are lined up PERFECTLY CENTER of cell on a metaphase plate as they attach to the centrosomes.

24
Q

What are visual cues when anaphase is occuring?

A

The sister chromatids get pulled apart by the mitotic spindle.

25
Q

What occurs in cytokinesis and telophase?

A

During cytokinesis, the cells pinch into two until they seperate into two identical versions.

During telophase, both cells have to undo some processes in order to resume being a normal cell. Such as uncondensing DNA. Spindle formation dissappears. Nuclear envelope reforms.

26
Q

What is the mitotic spindle made up of?

A

It’s made up of microtubule filaments created by centrosomes.

27
Q

Are spindle microtubules and and mitotic spindle the same thing?

A

Yes, they are pretty similar structure, both are made up of alpha and beta tubulin
except mitotic spindle is used in the process of mitosis and are a bit longer in size.

28
Q

What are asters and where are they located?

A

We can see asters near the centrosomes, they are shorter microtubules that do not attach to the chromosomes but still extend out of there.

29
Q

How do the chromosomes actually attach to the mitotic spindle and how do they get pulled to the other side of the cell?

A

Using a structure called kinetochore located on the chromosome.
The kinetochore is a motor protein complex that helps the chromosome move while dividing.

During anaphase, the microtubule is being depolymerized or chewed up into smaller parts by the kinetochore so that it disassembles.

30
Q

In cytokinesis, how does the cell exactly become pinched off into two daughter cells?

A

The microfilaments made up of actin form a ring that contracts in between the two identical cells. Eventually, it becomes so tight, they pinch off.
The pinched image of the two cells is called cleveage furrow.

31
Q

Does cytokinesis occur after telophase?

A

It occurs after anaphase and during telophase.

32
Q

Are plants and animal’s mitosis process the same?

A

No, they are different at the end, instead of cytokinesis occuring, a cell wall is formed between daughter and parent cell in order to break it off.

33
Q

How does a cell wall form between a parent and daughter cell in mitosis?

A

Vesicles fuse together into a substance called cell plate UNTIL it fully surrounds the edges between parent and daughter cells.

34
Q

Is the process of mitosis also the same in prokaryotes?

A

No, the process of mitosis is called binary fission and the steps are sort of different.

35
Q

What’s the basic process of binary fission and how is it different from mitosis?

A

Unlike mitosis, the DNA doesn’t have to be condensed and there’s no nucleus to be dissolved.
After DNA is copied, they go towards the opposite side of the cell and perform cytokinesis and the two cells break off.

35
Q

What’s the relationship between mitosis and binary fission history wise?

A

It’s theorized that mitosis is an evolved process of binary fission because there are some fungis that are a mix of binary fission and mitosis.

36
Q

How is the cell cycle process controlled?

A

It has a control system throughout the process where if a cell shouldn’t go through mitosis again, checkpoints during the process will terminate further execution.

37
Q

How does the checkpoint system control mitosis?

A

When a checkpoint signal is reached and a protein is not enzymatically attached to the checkpoint, the process will not move on until the protein or molecule comes and attaches.

38
Q

Where are the checkpoints located?

A

They occur during Interphase and are located between G1 and S and at the end of G2 before mitosis.

39
Q

What happens at the first checkpoint?

A

During the first checkpoint, a molecule acts as a gate. If a gate is down, the cycle continues. But if the gate is up, cells actually just exit the cell cycle and enter G0 phase.

40
Q

What is the G0 phase?

A

It’s a resting / sleeping phase in a cell where mitosis and its processes won’t occur.

41
Q

How does the second checkpoint work?

A

The second checkpoint in G2 decides how long should the cell division take. It uses the CDk and cyclin as a regulatory molecules as tools in deciding whether the cell should go ahead or not.

42
Q

How does cyclin-Cdk act as a regulatory proteins in G2 checkpoints?

A

Throughout the entire cycle, cyclin is being made so cyclin concentration increases till it reaches the G2 checkpoint. CDk doesn’t have to be made but instead is waiting for enough Cyclin to accumulate. When all of cyclin binds with all of CDk, this makes a MPF protein complex.

When there’s not enough cyclin made, there’s not enough MPF as needed in order to pass through the checkpoint.

43
Q

What’s the full form of a MPF

A

Maturing Protein Factor

44
Q

What happens to the cyclin after the G2 checkpoint is passed?

A

The cyclin is degraded into small pieces and is accumulated again throughout the cell cycle until it reaches G2 checkpoint again.

45
Q

How do cells know when to replicate and when to NOT?

A

From external factors that aren’t checkpoints such as other control signals

46
Q

What’s one process where cells know when to replicate and when to stop?

A

During anchorage dependence, cells only replicate when they are attached to something such as tissues or bones. So control signals sense that cells aren’t completely surrounding an achored body and hence continue to replicate.

But cells stop when they sense other cells all around them, this process is called density depenent inhibition.

47
Q

Do cancer cells exhibit density dependent inhibition?

A

No,they do not, which is why they are called cancer cells. They do not stop replicating and this rapid replicating causes cells to stop bodily functions as they take up all the space.

48
Q

Why do cancel cells not stop replicating? What are some other factors that help cancer cells grow?

A

Cancer cells stop listening to external cues such as perfoming anchorage dependence. Their checkpoints basically let them go through cell division as fast as they can. This is caused by 4 specific mutations in the genes.

  1. Loss of APC tumor suppressor
  2. K-ras oncogene
  3. Loss of DCC tumor suppressor
  4. loss of p-53 tumor suppressor
49
Q

How are cancer cells killed off?

A
  1. Through cancer cell drugs - they inhibit functions or processes at various phases of the cell cycle such as formation of mitotic spindle or stopping microtubules from depolymerizing.

Bio 1201 lsu (16 decks)

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