Mitosis And Meiosis

Question 1

Chromosome structure

Answer 1

Each replicated chromosome consists of 2 chromatids
Each replicated chromosome contains 2 identical DNA molecules
One chromosome = one DNA molecule before replication

After replication one chromosome -= 2 DNA molecules 2 chromatids

P arm = short
Q arm = long

Question 2

Metacentric

Answer 2

Equal sized p and q arm

Question 3

Submetacentric

Answer 3

P is shorter than q

Question 4

Acrocentric

Answer 4

P arm is almost non existent

Question 5

Telocentric

Answer 5

No p arm

Question 6

What are homologous chromosome

Answer 6

They have the same DNA sequence and have the same genes located on them

Genes on homologous chromosomes maybe be different varients- alleles

Question 7

Mitosis

Answer 7

Cell division for somatic cells

Production of 2 identical daughter ells
-with some chromosome content as parental cell

50 mitosis rounds during early development

Mitotic growth also necessary for some tissue
-epidermis , mucosae,bone marrow and spermatogonia

Question 8

Prophase

Answer 8

Spindles appear

Chromosome condense

Question 9

Prometaphase

Answer 9

Spindle attach to chromosome

Chromosomes condense further

Question 10

Metaphase

Answer 10

Chromosome align

Question 11

Anaphase

Answer 11

Centromeres divide

Sister chromatids move to opposite poles

Question 12

Telophase

Answer 12

Nuclear membrane reforms
Chromosome decondense
Spindle fibres disappear

Question 13

Cytokinesis

Answer 13

Cytoplasm divides

Parent cell becomes 2 daughter cells with identical genetic information.

Question 14

No disjunction

Answer 14

Missegregtion of chromosomes

Leads to aneuploidy- unusual amount of chromosome

Question 15

Meiosis

Answer 15

Special cell division

Chromosome number reduced- one round of replication and 2 rounds of division

Question 16

Consequences of meiosis

Answer 16

Generation of genetic diversity

• crossing over of genetic material in prophase 1
• random assortment of chromosomes in metaphase 1

Maintaining constant chromosome number from generation to generation

Question 17

What is the different between meiosis 1 ans 2

Answer 17

Homologous pairs of chromosomes lien up ad separate in meiosis 1 and in meiosis 2 chromosomes line up and chromatids separate

Question 18

Spermatogenesis

Answer 18

Cell division to produce male gametes

When a spermatogonium undergoes meiosis it becomes a spermatocytes

From spermatocyte (2n) to 4 sperm (n) in approximately 60 days

Question 19

Oogenesis

Answer 19

Cell division to produce female gametes

The oocyte arrests into meiosis 1 during prophase 1 and stays thee until puberty and there is the menstrual cycle

Every time we have the menstrual cycle - the oocyte is released from the arrest in prophase 1

From 1 oocyte (2n) to 1 egg (n) plus 3 polar bodes in 12-50 years

Question 20

what is nondisjunction

Answer 20

missegregation of chromosomes
leads to aneuploidy
which leads to monosomy- 1 chromatid
trisomy- 3 chromatids