Section 2 - Cell Cycle

Question 1

What is the cell cycle?

Answer 1

Cells reproduce through controlled growth and division in process called the cell cycle.

Question 2

The cell cycle produces cells that are genetically identical. What is the purpose of the cell cycle?

Answer 2

The growth of an organism, the repair of an organism, and the replacement of dead or dying cells.

Question 3

What are the 3 main phases of the cell cycle?

Answer 3

Interphase, mitosis, and cytokinesis.

Question 4

What is a centromere?

Answer 4

A region on the DNA where two sister chromatids are held together.

Question 5

What is a chromatin?

Answer 5

Double stranded DNA in its unpacked form.

Question 6

Interphase

Answer 6

The is is the longest stage in the cell cycle. Chromosomes are not visible during this phase as the chromosomes material chromatin is dispersed throughout the cell.

It is where the cells grows, develops into a mature functioning cell, copies its DNA, and prepares for division.

Question 7

What are the 3 phases of interphase?

Answer 7

G1 (growth 1 phase), s (synthesis phase), and G2 (growth 2 phase).

Question 8

Describe the 3 phases of interphase.

Answer 8

G1: cell grows and increases in size

S: DNA replication occurs

G2: cell replicates organelles in preparation for division and synthesizes ATP (energy)

Question 9

What are the parts of a duplicated chromosome?

Answer 9

Each chromosome is made up of two identical threads called chromatids. Each chromatid is joined by a region called the centromere.

Question 10

What are somatic cells?

Answer 10

All body cells except for sex cells.

Question 11

What is asexual reproduction?

Answer 11

A form of reproduction in which the offspring comes from a single organism, and not involved in the union of gametes (sexual reproduction).

Question 12

What is the purpose of mitosis?

Answer 12

To grow, repair, and maintain functionality in an organism.

Question 13

Mitosis is a type of?

Answer 13

Asexual reproduction.

Question 14

Mitosis occurs in most..

Answer 14

Somatic cells

Question 15

What are the 4 stages of mitosis?

Answer 15

Prophase, metaphase, anaphase, telophase/cytokinesis.

Question 16

Prophase

Answer 16

The cell condenses and thickens to form chromosomes.

Centrioles move to opposite ends of the cell, and form microtubules called spindle fibres.

Near the end of prophase, the nuclear membrane disintegrates and nucleolus disappears.

Question 17

Metaphase

Answer 17

The chromosomes arrange themselves at the middle of the cell and spindle fibres become attached to the centromere of the replicated chromosome.

Question 17

Anaphase

Answer 17

The centromere splits apart and chromatids are pulled to opposite poles of the cell by spindle fibres.

Question 18

Telophase

Answer 18

The chromatids have now reached a the poles of the cells and are called chromosomes again.

The chromosomes uncoil and lengthen into strands of less visible chromatin.

Spindle fibres break down and the centrioles replicate.

The nuclear membrane reforms in each cell and develops a nucleolus.

Question 19

What is a chromosome?

Answer 19

DNA in its coiled and packed form.

Question 21

What is a chromatid?

Answer 21

A piece of a chromosome.

Question 22

What is cytokinesis in mitosis?

Answer 22

The division of the cytoplasm.

Question 23

Describe the process of cytokinesis in animal cells.

Answer 23

During cytokinesis in animal cells, an INDENTATION forms in the plasma membrane along the cell’s equator.

The indentation deepens until the cell is pinched in two. The cytoplasm divides EQUALLY between the two cell halves.

Question 24

Cytokinesis ends with..

Answer 24

The separation of two genetically identical daughter cells.

Question 25

What is a cleavage furrow?

Answer 25

The indentation that appears during cytokinesis when the cell is preparing to divide.

Question 26

What is the difference between cell division in plant and animal cells?

Answer 26

Centrioles- In animal cells, centrioles are present and synthesizes spindle fibres. While plant cells do not have centrioles but spindle fibres do form.

Cytokinesis- in animal cells, the cells are pinched into 2 and a cleavage furrow forms. In plant cells, it requires formation of a cell wall and a cell plate forms.

Question 27

What are the types of twins?

Answer 27

(Monozygotic) Identical, (dizygotic) fraternal, and conjoined

Question 28

How do Dizygotic twins form?

Answer 28

When 2 separate eggs are released at the same time and are fertilized by two separate sperm.

Is referred to dizygotic because two zygotes form.

Question 29

How do Monozygotic twins form?

Answer 29

When a single egg zygote divides into two separate bodies in the first few day of development. Is referred to as monozygotic because a single zygote is formed.

Question 30

How do conjoined twins form?

Answer 30

If a zygote does not completely separate then the twins become stuck together.

Question 31

What is cloning?

Answer 31

The process that produces identical copies of genes, cells, or organisms.

Question 32

What are the different types of cloning?

Answer 32

Gene cloning, therapeutic cloning and reproductive cloning.

Question 33

Gene cloning

Answer 33

Producing multiple copies of genes or segment of DNA in foreign cells.

Question 34

Example of gene cloning

Answer 34

Example, gene cloning is used to produce lists of human insulin that can be injected into patients with diabetes.

Question 35

Therapeutic cloning and reproductive cloning

Answer 35

Both replace the nucleus of an egg cell with the nucleus of a somatic cell with the desired genes.

Question 36

The chromosome number (n) in mitosis is…

Answer 36

Diploid