Bio U1 - 1.6

Question 1

State the function of mitosis.

Answer 1

The function of mitosis is creating two identical daughter cells with genetically identical DNA

Question 2

List five processes which involve mitosis.

Answer 2

1. Tissue repair (for example burns or after injuries)
2. Growth of an organism (during childhood for example)
3. During embryonic development (zygote onward)
4. Replace existing cells that die naturally
5. Asexual Reproduction (generating two genetically identical daughter cells)

Question 3

State the names of the four phases of mitosis.

Answer 3

PMAT
- Prophase
- Metaphase
- Anaphase
- Telophase

Question 4

Draw typical eukaryotic cells as they would appear during the interphase and the four phases of mitosis.

Answer 4

Drawn in notebook

Question 5

Outline four events that occur during prophase.

Answer 5

1. Nuclear membrane begins to break apart
2. Nucleolus “disappears”
3. DNA supercoils into replicated chromosomes
4. Spindle fibers form and centrioles move towards the cell poles

Question 6

Outline the process of metaphase, inclusive of the role of microtubules and the kinetochore.

Answer 6

1. Replicated chromosomes align at the equator (meta = middle)
2. A protein complex called kinetochore, located at the centromere, is connectef to microtubules (a type of spindle fiber)

Question 7

Outline the process of anaphase.

Answer 7

The identical chromatids (now unreplicated chromosomes) are pulled towards the poles by motor proteins moving along the kinetochore microtubules.

Question 8

Outline four events that occur during telophase.

Answer 8

1. Nuclear membrane reforms
2. Nucleolus reappears
3. Chromosomes decondeses into chromatin
4. Spindle Fibers break apart

Question 9

Describe the structure of a replicated chromosome, including the centromere and sister chromatids.

Answer 9

Centromere is the location where two identical strands of DNA (sister chromatids) are attached
Chromosomes are supercoiled identical copies of DNA.

Question 10

Explain why chromosomes must condense during mitosis.

Answer 10

To more easily move to the poles of the cell

Question 11

Outline events of G1, S, G2 and G0 phases of interphase.

Answer 11

G1: cell growth and it performs its specialized functions (protein synthesis)
S: sythesis of DNA
G2: the cell makes the protein required for mitosis and cytokinesis
G0: cell is neither dividing or preparing to divide

Question 12

Define cytokinesis.

Answer 12

It is the division of the cytoplasm of the mother cell into two daughter cells

Question 13

State the difference between mitosis and cytokinesis

Answer 13

Mitosis refers to the division of the nucleus and DNA while cytokinesis refers to the division of the cytoplasm

Question 14

Contrast cytokinesis in plant and animal cells

Answer 14

Animals: Cleavage furrow
Plants: Cell plate

Question 15

Describe the formation of the cleavage furrow in animal cell cytokinesis

Answer 15

A ring of contractile proteins at the cell equator constrict, pulling in the cell membrane and creating a cleavage furrow. The cleavage furrows continues to pinch in until the two sides meet.

Question 16

​Describe the formation of the middle lamella and cell wall in plant cell cytokinesis

Answer 16

The middle lamella is a wall of pectin, which is produced by the Golgi and stored in vesicles. When called upon, they move to the equator of the cell and secrete pectin to form a cell plate that is later going to be coated with celullose to form a cell wall.

Question 17

Explain the role of cyclin and cyclin-CDK complexes in controlling the cell cycle.

Answer 17

Cyclins are proteins that the cell’s progression through the cell cycle. They act as switches which turn on CDKs which do the work of moving the cell through the cycle.

Question 18

State the role of cyclins D, B, A and E in the cell cycle.​

Answer 18

D (aka G1 cyclin): helps with the progression of the cell through G1 into S
E (aka S cyclin): Essential for DNA replication and centromere duplication
A: Helps induce DNA replication
B: Essential for the formation of mitotic spindles and the alingment of chromatids

Question 19

Define tumor, benign, malignant, metastasis, cancer, mutagen and carcinogen.

Answer 19

Tumor: A mass of tissue caused by abnormal growth
Benign: a tumor that lacks the ability to grow and metastasize
Malignant: a tumor that has the ability to spread and metastasize
Metastasis: when cells from a malignant tumor spread to other tissues through blood or lymph vessels
Cancer: a disease caused by malignant tumors
Mutagen: an agent, such as UV radiation, smoking, or radon, that cause genetic mutations
Carcinogen: a substance capable of causing cancer

Question 20

Describe why mutagens are not necessarily carcinogens.

Answer 20

Mutagens induce mutations in the DNA, only if that mutation leads to cancer then it is a carcinogen

Question 21

Describe how cancer arises, referring to accumulation of mutations over time.

Answer 21

Cells become cancerous after mutations accumulate in the genes that control the cell cycle. Around 60 mutations.

Question 22

Explain the relationship between proto-oncogenes, oncogenes, tumor suppressor genes and cancer.​

Answer 22

Proto-oncogenes are normal genes that code for protein (i.e. cyclins) that help the cell move through the cell cycle.
Oncogenes: mutated proto-oncogenes and they move the cell through the cell cycle even when it should not divide
Tumor supressor genes: they function to stop a cell from dividing when it shouldn’t
Cancer develops when both types of genes mutate and the cell divides without control

Question 23

Define significant as related to the relationship between two variables.

Question 24

Use epidemiological case study information to outline the relationships between smoking and cancer.​

Question 25

Determine the phase of mitosis of a cell viewed in a micrograph or with a microscope.

Answer 25

Drawn in notebook

Question 26

State the formula for calculation of a mitotic index.

Answer 26

pmat/ipmat

Question 27

Calculate the mitotic index of a tissue as seen in a micrograph.

Answer 27

Count the amount of cells in mitosis and divide them by the amount of cells in mitosis and interphase

Question 28

Outline the use of mitotic index calculations in diagnosis and treatment of cancer.

Answer 28

If a tissue is shown to have a higher mitotic index then it has cancer