Lab Practical 1

Question 1

Answer 1

Mitotic G1 Phase:

• Carries out biosynthetic activities characteristic of the cell
• Cell often increases in size as part of normal growth pattern

Question 2

Answer 2

Mitotic S Phase:

• DNA in the nucleus is copied
• Same number of chromosomes, double chromatids

Question 3

Answer 3

Mitotic G2 Phase:

• Centrosomes move to opposite sides of the nucleus
• Centrosomes: help organize mitotic spindle

Question 4

Answer 4

Mitotic Prophase:

• Chromosomes become condensed (easily visible)
• Mitotic spindle begins to form; consists of overlapping microtubules

Question 5

Answer 5

Mitotic Prometaphase:

• Nuclear membrane breaks down
• Some spindle fibers connect to chromosomes at the kinetochore formed at the centromere
• Kinetochore microtubules adjust their lengths so chromosomes become located at the metaphase plate
• Metaphase: when kinetochores finally reach metaphase plate

Question 6

Answer 6

Mitotic Anaphase:

• Adhesive protein in centromeres dissolve, chromatids separate (double chromosomes)
• Chromatids pulled apart by motor proteins that move alone kinetochore microtubules, and by lengthening of microtubules that span from pole to pole
• Daughter chromosomes are moves away from each other

Question 7

Answer 7

Mitotic Telophase:

• Nuclear membrane forms around the two groups of chromosomes
• Chromosomes decondense
• Spindle apparatus disappears

Question 8

Answer 8

Mitotic Cytokinesis:

• Often occurs during telophase but is separate; mitosis is chromosome movement and cytokinesis is cytoplasm division
• Animals: pinching off
• Plants: synthesis of a cell wall
• Back to originial one-chromatid chromosomes

Question 9

Answer 9

Meiotic Interphase (G1):

• Presence of membrane
• 1-chromatid chromosomes

Question 10

Answer 10

Meiotic Early Prophase I:

• 2-chromatid chromosomes

Question 11

Answer 11

Meiotic Late Prophase I:

• Spindle fibers form
• Condensation
• Crossing-over may occur

Question 12

Answer 12

Meiotic Metaphase I:

• Membrane disappears
• Spindle fibers attach
• Alignment at metaphase plate; independent assortment

Question 13

Answer 13

Meiotic Anaphase I:

• Chromosomes pulled to poles

Question 14

Answer 14

Meiotic Telophase I:

• Spindle fibers disappear

Question 15

Answer 15

Meiotic Interkinesis:

• Cell pinches off (total chromosomes in half)

Question 16

Answer 16

Meiotic Prophase II:

• Spindle fibers form
• Chromosomes align

Question 17

Answer 17

Meiotic Metaphase II:

• Chromosomes align on metaphase plate

Question 18

Answer 18

Meiotic Anaphase II:

• Chromatids separate (total chromosomes per cell double)

Question 19

Answer 19

Meiotic Telophase II:

• Spindle fibers disappear
• Chromosomes at poles
• Membrane reappears

Question 20

Answer 20

Meiotic Gametes/Spores:

• Cells pinch off into 4 (half chromosomes per cell, same total)