Chromosomes

Question 1

Define Cells

Answer 1

Cells are the structural and functional unit of life.

Question 2

define Cytokinesis

Answer 2

Cytokinesis is defined as the division of the cytoplasm of a cell

Question 3

In what stage of karyokinesis is the shape and size of a chromosome best seen?

Answer 3

Metaphase

Question 4

Define Crossing Over?

Answer 4

It is the process of exchange of genetic material between non-sister chromatids of the homologous chromosomes . it occurs during meiosis

Question 5

What is karyokinesis?

Answer 5

it is the division of the nucleus of the cell.

Question 6

What is mitosis?

Answer 6

It is the division of the cell into two identical daughter cells with each cell having the same number of chromosomes as the parent cell.it occurs in somatic (body) cells. aka equational divison.

Question 7

What is meiosis?

Answer 7

Meiosis occurs in the reproductive cells to produce the gametes. In meiosis the chromosome number is reduced to half. aka reductional division. It occurs in germ cells or reproductive cells.

Question 8

What is Synapsis?

Answer 8

During meiosis the pairing between the homologous chromosomes is called synapsis and the pair is called bivalent.

Question 9

What are the two phases of the cell cycle?

Answer 9

The Interphase and the mitotic phase (m1 phase )

Question 10

What are the three phases of Interphase?

Answer 10

1. First Growth Phase : Cells grows to the same size as parent cell. RNA and proteins are synthesized for Dna replication.
2. Synthesis Phase : Replication of DNA takes place. chromosomes are duplicated.
3. Second Growth Phase: More RNA and Proteins are Synthesized. (pre-mitotic phase) increase in volume of nucleus.

Question 11

What are the stages of mitosis?

Answer 11

1. Karyokinesis
   Prophase
   Metaphase
   Anaphase
   Telophase
2. Cytokinesis

Question 12

How many chromosomes do humans have?

Answer 12

46 (23 pairs)

Question 13

What are the two types of chromosmes?

Answer 13

1. Autosomes - 44
2. Sex Chromosomes or Allosomes - 2

Question 14

What are the 4 types of Chromatids on the basis of the centromere?

Answer 14

1. Telocentric
2. Acrocentric
3. Submetacentric
4. Metacentric

Question 15

Define Gene

Answer 15

Genes are the specific sequence of nucleotides on a chromosome that encode particular proteins which express in the form of some particular feature of the body .

Question 16

Who proposed the double helical structure of DNA?

Answer 16

Watson and Crick. Nobel Prize 1962

Question 17

descibe nucleotide?

Answer 17

pentose (sugar)
phosphate (above 2 form backbone of DNA molecule)
Nitrogenous base joined to complimentary nitrogenous base by hydrogen bond.

Question 18

What is chiasmata?

Answer 18

The points of attachment where crossing-over occurs.

Question 19

What is crossing over?

Answer 19

exchange of chromatid parts between the paternal and maternal chromatids of a pair of homologous chromosomes during meiosis.

Question 20

What are the four nitrogenous bases of DNA? what do they combine to?

Answer 20

Adenine, guanine, thymine and cytosine
A=T
G=_C

Question 21

in what stage of meiosis does crossing over occur?

Answer 21

in the pachytene stage