Meiosis

Question 1

Meiosis

Answer 1

Process that produces sex cells - occurs in the gonads (ovaries and testes), two divisions, result is four haploid cells (half the chromosomes needed to ensure correct number after fertilization), daughter cells genetically different

Question 2

Differences from Mitosis

Answer 2

• Two divisions (eight stages)
• Occurs in gonads
• Produces sex cells
• Produces four daughter cells with half the chromosomes of the parent cells (haploid)
• Daughter cells are genetically different

Question 3

The Human Life Cycle

Answer 3

In each generation, doubling of chromosome number from fertilization offset by halving number of chromosome during meiosis

Question 4

Stages of Meiosis

Answer 4

Interphase I, Prophase I, Metaphase I, Anaphase I, Telophase & Cytokinesis I, Prophase II, Metaphase II, Anaphase II, Telophase & Cytokinesis II

Question 5

Interphase I

Answer 5

Chromosomes replicates - each DNA strand (chromatin) unzips into two strands (loosely packed and not visible); two pairs of centrioles lie right outside nucleus

Question 6

Prophase I

Answer 6

Chromosomes condense; homologous chromosomes pair up, forming tetrads (synapsis), and attach to nuclear membrane; enzymes cut out sequences of DNA (genetic material) from the chromosomes and exchange them between the two (crossing over); centrioles separate and spindle fibres begin to grow from them; nuclear membrane disappears

Question 7

Metaphase I

Answer 7

Pairs of homologous chromosomes line up on metaphase plate, one on each side of plate; spindle fibres attach

Question 8

Anaphase I

Answer 8

Pairs of homologous chromosome are pulled apart from each other to opposite ends by spindle fibres

Question 9

Telophase & Cytokinesis I

Answer 9

Chromosomes arrive at opposite ends and new nuclear membranes start to form; rest of cell divides including cytoplasm; cleavage furrow forms; two haploid cells formed

Question 10

Prophase II

Answer 10

Chromosomes condense, centrioles separate and spindle fibres begin to grow from them, nuclear membrane breaks down

Question 11

Metaphase II

Answer 11

Chromosomes align along metaphase plate; spindle fibres attach to centromeres

Question 12

Anaphase II

Answer 12

Sister chromatids are pulled apart to opposite ends by spindle fibres

Question 13

Telophase & Cytokinesis II

Answer 13

Chromosomes arrive at opposite ends and new nuclear membranes start to form; rest of cell divides including cytoplasm; cleavage furrow forms; four haploid cells formed

Question 14

Difference in Females (to produce eggs)

Answer 14

During telophase & cytokinesis I, most of cytoplasm is distributed into one of two emerging cells, resulting in one large cell and one smaller cell - larger cell divides again, smaller cell (polar body) degenerates; during telophase & cytokinesis II, same thing happens and large cell becomes egg, smaller cell (polar body) degenerates