Mitosis

Question 1

What are the stages of Mitosis?

Answer 1

Prophase
Prometaphase
Metaphase
Anaphase
Telophase

Question 2

What percent of the cell cycle is Mitosis?

Answer 2

10%

Question 3

What are the stages of Interphase?

Answer 3

G1: first gap phase. Cell begins to grow.
S Phase: Duplication of chromosomes
G2: second gap phase: cell prepares to divide

Cell growth is seen during all three stages. The cell continues to make organelles and proteins

Question 4

How are chromosomes moved?

Answer 4

The centrosome is duplicated and they move to opposite sides of the cell.

The centrosome creates a microtubule structure called spindle fibers that connect to the kinetochore on the chromosome

The spindle fibers control the chromosome movement during Mitosis

Question 5

How many chromosomes does a human cell have?

Answer 5

44 autosomes and 2 sex chromosomes ( Two XX or XY)

Question 6

Describe Prophase

Answer 6

• Nucleoli disappear
• Chromosomes condense
• Centrioles (Centrosomes) move to opposite sides of the cell
• Mitotic spindle starts its formation
• Chromatin fibers become tightly coiled; chromosomes are observable under a light microscope

Question 7

Prometaphase

Answer 7

• Chromosomes become condensed
• Nuclear envelope fragments
• Spindle fibers attach to the kinetochore

Question 8

Metaphase

Answer 8

• Centrosomes are officially at opposite ends of the cell
• Sister chromatids of each chromosome are attached to the spindle
• Chromosomes are now lined up at the spindle equator

Question 9

Anaphase

Answer 9

• Shortest stage of mitosis
• Cohesion proteins are cleaved, thus allowing the sister chromosomes to separate from each other and move to opposite poles.
• At the end of Anaphase cytokinesis begins.

Question 10

Telophase

Answer 10

• 2 daughter nuclei form, each with a diploid 2N number
• Cytokinesis occurs, but often begins in anaphase
• Chromosomes decondense
• New nuclear membranes form

Question 11

How is cytokinesis different in animals and plants?

Answer 11

• In animal cells, cytokinesis involves the formation of a cleavage furrow that essentially pinches the cells into two.
• In plant cells, since they have a cell wall, they reproduce with the formation of a cell plate. This partitions off the daughter cells and eventually becomes the cell wall.

Question 12

How do bacteria and Archae reproduce?

Answer 12

Binary fission:

• A single chromosome is replicated, then it divides into two genetically identical daughter cells.
• A sexual reproduction

Question 13

What is the G1 checkpoint?

Answer 13

• The cell will give the go ahead to start the duplication of chromosomes or give a signal to halt division.
• If the checkpoint is not passed, the cell switches to G0 phase.
• Most of our cells are in G0 phase
• Growth factors may allow G0 to switch back to G1
• Various enzymes and growth factors are involved in the checkpoint, and can be influenced by things like DNA damage.

Question 14

Cancer

Answer 14

Cancer is a disruption of the checkpoints of cell division

Question 15

Colchicine

Answer 15

A drug that disrupts microtubule formation. It’s a form of chemotherapy

Question 16

somatic cells

Answer 16

All body cells excluding sex cells (gametes)

Question 17

gametes

Answer 17

sex cells: eggs and sperm

Question 18

genome

Answer 18

The genetic information in the cell

Question 19

aster

Answer 19

• an array of microtubules that extends from each centrosome.
• These are different than the spindle fiber.
• Astral means star. These microtubules form a star shaped structure around the centrosome attaching it to the cell membrane and coordinating with the spindle fibers to help drive mitosis

Question 20

spindle

Answer 20

structure made up of proteins and microtubules. The spindle includes centrosomes, asters, and microtubules

Question 21

zygote

Answer 21

fertilized egg (2N)

Question 22

apoptosis

Answer 22

• Programmed cell death.

- Neighboring cells suffer no damage

Question 23

Tumor

Answer 23

clump of overlapping cells

- can be malignant or benign

Question 24

neoplasm

Answer 24

a new and abnormal growth

Question 25

What are two factors that limit cell size

Answer 25

• Nucleus capacity: It must have enough DNA to replicate all the mRNA needed for translation of proteins
• Surface area to volume: As the cell grows, the surface area to volume ratio shrinks. At a certain point, the surface area of the cell membrane no longer is large enough to bring in the nutrients that the cell needs to live, compared to the size of the cell volume. This is when cell division occurs.