Mitosis (Eukaryotic Cell Division)

Question 1

How do Acellular RNA organisms store genetic information?

Answer 1

Viruses - Double-stranded or Single-stranded DNA or RNA

Question 2

How do prokaryotic organisms store genetic information?

Answer 2

Bacteria - Circular, single copy, naked (not surrounded by lots of proteins) double-stranded DNA

Question 3

How do eukaryotic organisms store genetic information?

Answer 3

Protists, Fungi, Plants, Animals - Linear, > or equal to 1 copy, histone-bound DNA; sexual cycle

Question 4

What is the length of 3000 base pairs (bp) roughly equal to in length?

Answer 4

1 x 10^6 meters

Question 5

How much DNA does each human cell roughly carry in length?

Answer 5

2 meters

Question 6

What is a karyotype?

Answer 6

An ordered, visual representation of the chromosomes in a cell

Question 7

How do you see a karyotype (what’s the process)?

Answer 7

Take a sample of blood, treat the cells with mitogen (to start mitosis) and then with colchicine to stop mitosis. Use a stain and then you will see all of the pairs of homologous chromosomes randomly. Then take a picture and line them up in order of size.

Question 8

What homologous pairs make up the human karyotype?

Answer 8

Total of 23 chromosomes:
1 - 22 are autosomes
X & Y are sex chromosomes

Question 9

What do multicellular organisms depend on cell division for?

Answer 9

Development from a fertilised cell, growth to adult (10^14 cells), repair.

Question 10

How does a eukaryotic cell divide its DNA equally?

Answer 10

Using the cell cycle

Question 11

What phases make up the cell cycle?

Answer 11

Interphase: G1 Phase, S Phase, G2 phase.
Mitotic (M) Phase: Mitosis (Prophase, Metaphase, Anaphase, Telophase), Cytokinesis

Question 12

What happens when you duplicate the chromosomes?

Answer 12

Two sister chromosomes (of each homologous chromosome) are formed and held together by the centromere. They carry identical copies of DNA.

Question 13

Describe what happens in each of the phases in interphase.

Answer 13

G1 - All organelles and cytoplasmic components replicate + normal cell activity
S - DNA replicates + normal cell activity
G2 - All enzymes needed to aid in the process off cell division are produced
Cell spends a lot of time in this phase.

Question 14

What happens in Prophase?

Answer 14

Chromosomes condense and become visible as two sister chromatids held together at the centromere, cytoskeleton disassembles as the spindle apparatus/mitotic spindle starts to form (in animal cells centrioles migrate to opposite poles, establishing abridge of microtubules), nuclear envelope starts to disintegrate.

Question 15

What happens in Prometaphase?

Answer 15

Asters (ends on the spindle) move towards opposite ends of the cell, microtubules called kinetochore connect to the centromeres of the sister chromosomes, nonkinetochore microtubules don’t connect to anything

Question 16

What happens in Metaphase?

Answer 16

Kinetichore microtubules pull the centromeres into line along the metaphase plate.

Question 17

What happens in Anaphase?

Answer 17

Degradation of proteins that hold sister chromatids together. Non-kinetochore microtubules lengthen. Kinetochore microtubules contract essentially pulling the two sister chromatids apart so one set of sister chromosomes goes to one end of the cell and the other to the other end. They are now called daughter chromosomes.

Question 18

What happens in Telophase?

Answer 18

The process of pulling the daughter chromosomes to opposite ends of the cells continues. Cleavage furrow forms in the centre of the cell. This indentation is made from a constricting belt of actin filaments surrounding the inside of the cells circumference. Chromosomes begin uncondensing and nuclear envelope reforms. Then the mitotic spindle dissasembles as the microtubules are broken down into tubules monomers which can be used to form the cytoskeleton of the daughter cells.

Question 19

What happens in Cytokinesis?

Answer 19

In animal cells: Extends the cleavage furrow to completely separate the newly formed daughter cells.
In plant cells: Vesicles form an expanding membrane partition called the cell plate, it then finishes the separation of the two daughter cells.