Chapter 5.2

Question 1

Mitosis is the process

Answer 1

of nuclear division by which two genetically identical daughter nuclei are produced that are also genetically identical to the parent cell nucleus (they have the same number of chromosomes as the parent cell)

Question 2

-Although mitosis is, in reality, one continuous process, it can be divided into four main stages -These stages are:

Answer 2

—–Prophase

—–Metaphase

—–Anaphase

—–Telophase

-Most organisms contain many chromosomes in the nuclei of their cells

Question 3

Prophase

Answer 3

• Chromosomes condense and are now visible when stained
• The chromosomes consist of two identical chromatids called sister chromatids (each containing one DNA molecule) that are joined together at the centromere
• The two centrosomes (replicated in the G2 phase just before prophase) move towards opposite poles (opposite ends of the nucleus)
• Spindle fibres (protein microtubules) begin to emerge from the centrosomes (consists of two centrioles in animal cells)
• The nuclear envelope (nuclear membrane) breaks down into small vesicles

Question 4

centromere

Answer 4

The centromere is the place where the two copies of DNA ( after replication has occurred) are joined together. It is a visible as a constriction in chromosomes and is the site of attachment for the spindle fibres

Question 5

Metaphase

Answer 5

• Centrosomes reach opposite poles
• Spindle fibres (protein microtubules) continue to extend from centrosomes
• Chromosomes line up at the equator of the spindle (also known as the metaphase plate) so they are equidistant to the two centrosome poles
• Spindle fibres (protein microtubules) reach the chromosomes and attach to the centromeres
• Each sister chromatid is attached to a spindle fibre originating from opposite poles

Question 6

Anaphase

Answer 6

• The sister chromatids separate at the centromere (the centromere divides in two)
• Spindle fibres (protein microtubules) begin to shorten
• The separated sister chromatids (now called chromosomes) are pulled to opposite poles by the spindle fibres (protein microtubules)

Question 7

Telophase

Answer 7

• Chromosomes arrive at opposite poles and begin to decondense
• Nuclear envelopes (nuclear membranes) begin to reform around each set of chromosomes
• The spindle fibres break down

Question 8

Cytokinesis

Answer 8

during this stage the cytoplasm is divides forming two genetically identical cells and it takes place after the telophase stage of mitosis

-This is the physical separation of the parent cell into two genetically identical daughter cells and occurs once a new nucleus has completely re-formed at each pole of the parent cell at the end of telophase

Question 9

Cytokinesis in plants

Answer 9

a ‘cell plate’ (the precursor to a new cell wall) forms at the site of the metaphase plate. Once the cell plate reaches the cell walls of the parent cell, new cell walls are produced, separating the new daughter cells

Question 10

Cytokinesis in animals

Answer 10

a ‘cleavage furrow’ forms and separates the daughter cells

Question 11

meristems

Answer 11

Growth in plants occurs in specific regions