Chapter 14: Mitosis and Meiosis

Question 1

What is a karyotype?

Answer 1

The chromosomes contained in a cell, usually listed in descending order of size

Question 2

What are homologous chromosomes?

Answer 2

Chromosomes of the same length and shape, and have the same alleles (genes)

Question 4

What is interphase?

Answer 4

An active period where protein synthesis, DNA replication and increase in number of mitochondria (and chloroplasts in plant cells) occur

Question 5

What happens to the centrioles during interphase in animal cells?

Answer 5

They divide to form two pairs of centrioles

Question 6

What is the centromere in a chromotid?

Answer 6

The region where two chromatids are most closely attached

Question 7

What is mitosis?

Answer 7

A nuclear division where the daughter nuclei produced contains the same number of chromosomes as the parent nucleus (daughter cells are identical to the parent cell)

Question 8

What are the four stages of mitosis?

Answer 8

1) Prophase
2) Metaphase
3) Anaphase
4) Telophase

Question 9

What happens during prophase in mitosis?

Answer 9

Early prophase: Microtubules form around the centriole, and the two pairs of centrioles move to the opposite poles of the cell, connected by spindle fibres
Late prophase: The nuclear envolope disappears, and a spindle forms with the spindle fibres extending from one pole to another

Question 10

What happens during metaphase in mitosis?

Answer 10

Chromosomes line up around the equator of the spindle. and the centromere of each chromosome is attached to a spindle fibre

Question 11

What happens during anaphase in mitosis?

Answer 11

The centromeres split, and the sister chromotids are dragged to the opposite poles of the cell by the spindle fibres

Question 12

What happens during telephase in mitosis?

Answer 12

The spindle fibre breaks down, and a nuclear envelope forms around the chromosomes at each pole of the cell. A nucleolus forms and the chromosomes uncoil and lengthen to become thin chromatin threads

Question 13

What happens during cytokinesis?

Answer 13

The cytoplasm divides after mitosis

Question 14

What are some differences in mitosis in plant cells comparred to animal cells?

Answer 14

1) There are no centrioles in plant cells
2) Cleavage of cytoplasm does not happen for plant cells
3) A cell plate is formed inbetween two daughter nuclei in plant cells

Question 15

How does growth occur?

Answer 15

Cells undergo mitosis, and new cells are differentiated to form tissues and organs

Question 16

What are cancerous tumor cells?

Answer 16

Undifferentiated cells that continue to divide uncontrollably

Question 17

When does a cell undergo apoptosis?

Answer 17

When a genetic error occurs within a cell, it will undergo apoptosis, which is programmed cell death (suicide)

Question 18

How are tumors generated?

Answer 18

When errors in DNA replication or mitosis cause the uncontrollable division of cells. This might cause a mass of abnormal cells within normal tissue

Question 19

What is a benign tumor?

Answer 19

A tumor where the abonormal cells remain at their original site

Question 20

What happens if a tumor is malignant?

Answer 20

It will multiply and spread to neighbouring cells and tissues where they form secondary tumors

Question 21

What is meiosis?

Answer 21

A form of nuclear division that produces daughter nuclei containing half the number of chromosomes as the parent nucleus (reduction division

Question 22

Where does meiosis often occur?

Answer 22

At the reporductive organs of organisms to form gamates

Question 23

What is the difference between a diploid an haploid cell?

Answer 23

A diploid cell has both pairs of chromosomes, while a haploid cell has one set of each homologous pair of chromosomes

Question 24

What is the difference between meiosis 1 and 2?

Answer 24

Meiosis 1 is the seperation of homologous chromosomes, while meiosis 2 is the seperation of two sister chromatids

Question 25

Why is meiosis required prior to fertillisation in sexual reproduction?

Answer 25

Since sexual reproduction involves the fusion of two gamates, the zygote will have double the normal number of chromosomes. Therefore meiosis is required to bring the number of chromosomes back to the normal amount

Question 26

What happens during prophase 1 in meiosis?

Answer 26

Chromatin threads condense to form chromosomes, and asters form around the centrioles which move apart to opposite poles of the cell. The spindle fibres form, and the nuclear envolope and nucleolus disappears.
Additionally, in meiosis, homologous chromosomes pair up with their sister chromatids along their whole length. The chromatids of homologous chromosomes may cross and twist around each other, causing them to break off and exchange parts (crossing over). This produces new combinations of alleles along the chromosomes

Question 27

What happens during metaphase 1 in meiosis?

Answer 27

The pairs of homologous chromosomes arrange themselves along the equator of the cell, and the two chromosomes of each pair face opposite poles of the cell, and each chromosome is attached to a spindle fibre

Question 28

What happens during anaphase 1 in meiosis

Answer 28

The homologous chromosomes seperate, and are pulled to opposite poles of the cell. In meiosis, the chromosomes are still made of two chromatids

Question 29

What happens during telophase 1 in meiosis?

Answer 29

A nuclear membrane forms around the chromosomes at each pole

Question 30

What happens during cytokinesis 1 in meiosis?

Answer 30

The cytoplsm cleaves producing two daughter cells, each with the haploid number of chromomes, and the centrioles replicate

Question 31

What happens during prophase 2 in meiosis?

Answer 31

The centrioles move to opposite poles, the nuclear envolope breaks down, and the spindle fibres appear

Question 32

What happens during metaphase 2 in meiosis?

Answer 32

The chromosomes arrange themelves along the equator of the spindle

Question 33

What happens during anaphase 2 in meiosis?

Answer 33

The centromeres divide, and the sister chromatids seperate. The daughter chromatids are pulled to opposite poles of the cell

Question 34

What happens during telophase 2 in meiosis?

Answer 34

The spindle fibres disappear, and the nuclear envelope forms around the two daughter chromosomes at each pole. A nucleolus reforms

Question 35

What happens during cytokinesis in meiosis?

Answer 35

The cytoplasm cleaves into two, and two daughter cells are produced. The daughter cells have a haploid number of chromosomes as the parent cell

Question 36

What is the difference between metaphase 1 and 2?

Answer 36

In metaphase 1, the chromosomes arrange themselves along the equator of the cell (vertically). In metaphase 2, the chromosomes arrange themselves along the equator of the spindle (horizontally)