Cell Cycle and Mitosis

Question 1

what do eukaryotic cells divide by once they’ve entered the cell cycle

Answer 1

-mitosis
or
-meiosis

Question 2

how do prokaryotic cells replicate

Answer 2

-by binary fission

Question 3

how do viruses undergo cell division

Answer 3

-they don’t as they are non living

Question 4

explain the process of binary fission

Answer 4

-the circular DNA and plasmids replicate
-the cytoplasm splits to create two daughter cells
-each daughter cell has one copy of the circular DNA but a variable number of plasmid copies

Question 5

what are the three key stages of the cell cycle

Answer 5

-interphase (g1,2,g2)
-nuclear division (mitosis or meiosis)
-cytokinesis

Question 6

what happens during interphase

Answer 6

-the organelles duplicate
-the cell grows
-DNA replicates
-the longest stage

Question 7

what does mitosis create

Answer 7

-two identical diploid cells
-cells with identical DNA for growth and repair

Question 8

what does meiosis create

Answer 8

-four genetically different haploid cells
-gametes

Question 9

what is cytokinesis

Answer 9

the division of the cytoplasm to create new daughter cells

Question 10

what are the four key stages of mitosis

Answer 10

-prophase
-metaphase
-anaphase
-telophase

Question 11

what does mitosis involve

Answer 11

-one round of division

Question 12

example of growth and repair from mitosis

Answer 12

in the clonal expansion of B cells in the humoral response

Question 13

what happens in the prophase

Answer 13

-chromosomes condense and become visible
-nuclear envelope disintegrates

Question 14

describe the prophase in animal cells

Answer 14

-the centrioles separate and move to opposite poles of the cell
-centrioles create spindle fibres which are released from both poles to create spindle apparatus

Question 15

how is the prophase different in plant cells

Answer 15

-plants have spindle apparatus
-lack centrioles

Question 16

describe what happens during the metaphase

Answer 16

-the chromosomes align along the equator of the cell
-the spindle fibres released from the poles now attach to the centromere and chromatid

Question 17

describe what happens during the anaphase

Answer 17

-the spindle fibres start to retract and pull the centromere and chromatids they are bound to towards opposite poles
-this causes the centromere to divide into two and the individual chromatids are pulled to each opposite pole
-separated chromatids are now called chromosomes

Question 18

what does the anaphase require

Answer 18

-energy
-in the form of ATP
-provided by respiration
-in the mitochondria

Question 19

describe what happens during the telophase and cytokinesis

Answer 19

-the chromosomes are now at each pole of the cell and become longer and thinner again
-the spindle fibres disintegrate and the nucleus starts to reform
-the cytoplasm splits in two to create two new genetically identical cells

Question 20

how is the mitotic index calculated

Answer 20

-counting how many cells are visible in the field of view
-counting the number of visible cells that are in a stage of mitosis

Question 21

mitotic index calculation

Answer 21

the number of cells in mitosis / the total number of cells
x100