cell cycle and mitosis

Question 1

how do prokaryotic cells divide

Answer 1

-binary fission
-involving the circular DNA and the plasmids (if present) replicating and then the cytoplasm splitting to create two daughter cells
-each daughter cell has one copy of the circular DNA but a variable number of plasmid copies.

-viral replication occurs inside the host cells and involves the injection of the nucleic acid into the cell.

Question 2

The cell cycle

made up of what three stages

Answer 2

• interphase ( G1, S, G2 )
  -nuclear division ( mitosis or meiosis)
  -cytokenisis

Question 3

Interphase

Answer 3

-longest stage in the cell cycle
-interphase is when organelles duplicate
-the cell grows
-then DNA replicates.

Question 4

Nuclear division

Answer 4

-either mitosis (creating two identical diploid cells) or meiosis ( creating four genetically different haploid cells)
-mitosis creates cells with identical DNA for growth and repair.
-meiosis creates gametes.

Question 5

cytokinesis

Answer 5

-final stage
-division of the cytoplasm to create new daughter cells

Question 5

4 key stages of mitosis

Answer 5

-prophase
-metaphase
-anaphase
-telophase

Question 6

mitosis

Answer 6

-involves one round of division
-results in two diploid, genetically identical daughter cells.
-mitosis for growth and repaire.g clonal expansion of B cells in the humoral response

Question 7

prophase

Answer 7

-chromosomes condense and become visible
-nuclear envelope disintegrates
-nucleolus disappears

-in animals cells: extra info
centrioles seperate and move to opposite poles of the cell
the centrioles are responsible for creating spindle fibres which are released from the both poles to create a spindle apparatus
these will attach to the centromere and chromatids in later stages
pants have spindle apparatus but lack centrioles.

Question 8

metaphase

Answer 8

-the chromosomes align along the equator of the cell

the spindle fibres released from the poles now attach to the centromere and chromatid

Question 9

anaphase

Answer 9

-spindle fibres start to retract and pull the centromere and chromatids as they are bound toward opposite poles

this causes the centromere to divide into two and the individual chromatids are pulled to each opposite pole

these separated chromatids and now referred to as chromosomes.

this stage requires energy in the form of ATP which is provided by respiration in the mitochondria

Question 10

telophase and cytokinesis ( end of the cell cycle )

Answer 10

-chromosomes are now at each pole of the cell and become longer and thinner again
-the spindle fibres disintegrates and the nucleus starts to reform

-final stage in the cell cycle
-when the cytoplasm splits in two to create the two new genetically identical cells

myosinII and actin filament ring contract to cleave cell in two.

Question 11

mitotic index calculation

Answer 11

the total number of cells

if a percentage X100