2 Cells- Mitosis and cancer

Question 1

What are the 2 major stages of the cell cycle?

Answer 1

1.) Interphase- cell grows, DNA replicated
2.) Mitotic phase- replicated DNA, cytoplasmic contents separate, cell divides

Question 2

What are the 3 stages of interphase and what happens?

Answer 2

G1- cell grows
S- DNA + organelles replicates (semi-conservative), 2 copies of every chromosomes
G2- Cell grows more before mitotic phase begins

Question 3

Why do multicellular organisms go through mitosis?

Answer 3

To grow and repair damaged tissues

Question 4

What are the stages of mitosis (in order)

Answer 4

PMAT
Prophase, Metaphase, Anaphase, Telophase

Question 5

What happens during prophase?

Answer 5

-Nuclear envelope breaks down, nucleolus disappears. Chromosomes free-float in the cytoplasm
-Chromosomes coil more tightly, become shorter and fatter; can be seen on light microscope
-Centrioles (protein bundles) move to opposite poles of cell
-Microtubules form mitotic spindle between centrioles

Question 6

What happens during metaphase?

Answer 6

-Chromosomes line up along mid-line of cell
-Chromosomes maximally condensed, attached to spindle by centromere

Question 7

What happens during anaphase?

Answer 7

-Chromosomes break into 2 chromatids, sister chromatids separate at centromere
-Spindles contract, pull chromatids to each pole of cell

Question 8

What happens during telophase?

Answer 8

-Chromatids reach opposite poles and start to decondense (unravel), becoming chromosomes again
-Nuclear envelopes reform around chromosomes, two nuclei now

Question 9

What happens during cytokinesis?

Answer 9

Division of the cytoplasm, which usually occurs during the cell cycle

Question 10

How do you calculate mitotic index?

Answer 10

Number of cells in mitosis / total number of cells

Question 11

What causes the formation of tumours and cancer?

Answer 11

Uncontrolled cell division

Question 12

How does uncontrolled cell division and a tumour happen ?

Answer 12

Error> changes to DNA nucleotide sequence> gene mutation> faulty protein> change in the cell, allows more mistakes> errors passed through to daughter cells> more generations> mutations accumulate> uncontrolled growth of mutated cells>tumour

Question 13

How can cancer be treated?

Answer 13

By targeting the phases of the cell cycle
S phase- Where DNA replicates. Errors can lead to tumours so drugs can be targeted to damage DNA and kill cells to prevent tumour spreading
G1- Where new organelles are produced, cell grows. If genes encoding the enzyme involved in this are mutated, cell cycle alters. Drugs can inhibit G1, treating cancerous cells- halting the cell cycle and killing the cells