MITOSIS AND MEIOSIS

Question 1

what is mitosis?

Answer 1

• division that maintains same number of chromosomes producing two new identical cells

Question 2

what is meiosis?

Answer 2

• division that halves the number of chromosomes, producing 4 haploid cells.
• genetically different

Question 3

what is a ploidy?

Answer 3

• how many complete sets of chromosomes a cell has

Question 4

what is a nucleus?

Answer 4

• membrane bound region of cell that contains chromatin.
• and in which transcription to mRNA ocurs.

Question 5

what is a nucleolus?

Answer 5

• region within nucleus (not membrane bound) in which ribosomes are made

Question 6

what is interphase?

Answer 6

• stage where cell spends most of life.
• cell actively consumes nutrients.

Question 7

what is gap 1 of interphase?

Answer 7

• cell grows and metaboizes normally.
• grows to double size
• makes more organelles and cytoplasm

Question 8

what is synthesis of interphase?

Answer 8

• more DNA is synthesised

Question 9

what is gap 2 of interphase?

Answer 9

• mitochondria divides by binary fission
• cell keeps growing

Question 10

what is prophase?

Answer 10

• chromosomes condenses out of chromatin.
• nucleoli breaks down
• centrosomes move apart
• microtubules reorganise
• Microtubules have formed short asters on centrosomes and beginning of mitotic spindle.

Question 11

what is prometaphase?

Answer 11

• nuclear envelope breaks down into vesicles
• membrane vesicles visible
• mitotic spindle is formed
  kietochores form

Question 12

what is metaphase?

Answer 12

• chromosomes align along equator of cell
• chromosomes are aligned along the equator of the cell.

Question 13

what is anaphase?

Answer 13

• protein securin blocks anaphase from starting till everything is ready.
• anaphase promoting complex destroys it.

Question 14

ANAPHASE A?

Answer 14

• ANAPHASE A = kinetochore microtubules pull on the chromatids pulling them apart and moves towards poles.

Question 15

ANAPHASE B?

Answer 15

• microtubules move towards the middle of the cell and pushes against one another.
• pushes chromatids nearer to the poles

Question 16

what is telophase?

Answer 16

• one nuclear envelope re- forms
• chromatids condense into chromatin and nucleoli reform
• mitotic spindle in disassembled.
• cytokinesis occurs - myosin and actin around equator of cell contracts and splits cell into two daughter cells.

Question 17

interphase in meiosis?

Answer 17

• G1 AND S PHASE ONLY OCCURS

Question 18

meiosis 1 = prophase 1?

Answer 18

crossing over events but otherwise same as mitosis
1. leptonene pahse
2. zygotene phase
3. pachytene phase
4. diplotene phase

Question 19

what is the leptonene phase?

Answer 19

• pairs of sister chromatids are copied and becomes tightly associated.
• some elements of synaptonemal complex assemble between each pair of chromatids.

Question 20

what is zygotene phase?

Answer 20

• homologous chromosomes line up next to each other.

Question 21

what is pachytene phase?

Answer 21

• homologous recombination occurs by crossing- over.
• chiasmata form at contact points.
• chromatids exchnage info

Question 22

what is diplotene phase?

Answer 22

• synaptonemal complex degrades.
• chiasmata not degraded

Question 23

meiosis 1 = metaphase 1 and anaphase 1

Answer 23

• happens much like mitosis but with chromosomes at poles of cell

Question 24

what is interkinesis?

Answer 24

two daughter cells
produced will have a little rest before
proceeding after telophase I

Question 25

what happens in meiosis 2?

Answer 25

• happens like mitosis but for each of two daughter cells made in meisois 1