Cell Division ( MITOSIS)

Question 1

What is Mitosis?

Give definition, characteristics, importance and why it occurs

Answer 1

• A replication of a cell to form two identical cells.

1. It involves the division of somatic ( body cells not reproductive)
2. It produces diploid cells
3. Importance: growth and repair

• Mitosis occurs so that each new daughter cell has a nucleus with a complete set of chromosomes

Question 2

INTERPHASE (GROWTH AND PREPARATION)

Answer 2

RESTING STAGE (NO CELL DIVISION OCCURS)

• IN THIS STAGE, CELL GROWS IN SIZE
• ORGANELLES & DNA REPLICATE
• PROTEIN SYNTHESIZE
• CELL PREPARES TO DIVIDE.

Question 3

What happens when a cell isn’t dividing

Answer 3

• DNA molecules are in an extended state, uncondensed= chromatin
• Cell can only replicate and transcribe DNA when in an extended state.

Question 4

WHAT ARE THE FOUR STAGES OF MITOSIS

Answer 4

Prophase, Metaphase(middle), Anaphase (away) , Telophase (cytokinesis)

Question 5

EXPLAIN FULLY WHAT HAPPENS IN PROPHASE?

Answer 5

• CHROMOSOME CONDENSES AND BECOMES MORE VISIBLE.
• CENTRIOLES FORM STAR SHAPED ASTERS THAT MOVE TO OPPOSITE POLES.
• SPINDLE FIBERS ( SPECIALIZED MICROTUBES) FORM AND RADIATES FROM THE CENTRIOLES
• NUCLEUS MEMBRANE BREAK DOWN AND DISAPPEARS.
• NUCLEIC DISINTEGRATES

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Question 6

EXPLAIN FULLY WHAT HAPPENS IN METAPHASE?

Answer 6

• Chromosomes align at the center of the cell.
• Centrioles attach spindle fibers at opposite poles.
• Spindle fibers connect to chromosomes.
• Nucleus membrane disappears.

Question 7

Explain fully what occurs in anaphase

( Rememer the phrase away )

Answer 7

• Chromosomes break at the centromere.
• SIster chromatids pulled towards opposite ends of the cell.
• Spindle fibers pull chromosomes to opposite poles.

Question 8

Explain fully what happens in Telophase?

Answer 8

• The cell constricts (narrow at the centre)
• Nucleus membrane are formed around groups of chromsomes.
• Chromosomes condense back to their stringy form (decondense)
• nucleolus reappears

Question 9

Explain fully What is Cytokinesis

(how does plants and animal cells undergo cytokinesis)

Answer 9

• Cytokinesis is the splitting of a cell into two new cells.
• Plant cells undergo cytokinesis by forming a new cell wall between two daughter nuclei
• Animal cells undergo cytokineis through pinching of cytoplasm.

Question 10

How does Mitosis effect life?

( Its uses and importance )

Answer 10

Wound healing: Replaces damaged cells due to injuiry

Immune Defense:
Creates antibodies to trap bacteria and get rid of them
Creates memory cells so that it can be prepared for the invader later.

Replacement of dying cells:
Skin cells undergo mitosis to produce new skin cells.
Hair undergo mitosis at the base.