1.6 Cell devision

Question 1

Two main phases of the cell cycle

Answer 1

Interphase

M phase

Question 2

Interphase

Answer 2

G1 – First intermediate gap stage in which the cell grows and prepares for DNA replication
S – Synthesis stage in which DNA is replicated
G2 – Second intermediate gap stage in which the cell finishes growing and prepares for cell division

Question 3

M phase

Answer 3

Mitosis

Cytokinesis

Question 4

Mitosis

Answer 4

Nuclear division, whereby DNA (as condensed chromosomes) is separated into two identical nuclei

Question 5

Cytokinesis

Answer 5

Cytoplasmic division, whereby cellular contents are segregated and the cell splits into two

Question 6

Processes that occur in the interphase

Answer 6

DNA replication 
Organelle duplication 
Cell growth 
Transcription / translation 
Obtain nutrients
Respiration (cellular)

Question 7

Features of chromatin

Answer 7

loosely packed
DNA is accessible to transcriptional machinery and so genetic information can be translated
in all non-dividing cells and throughout the process of interphase

Question 8

Features of chromosome

Answer 8

packaged into a tightly wound and condensed chromosome
DNA is able to be easily segregated however is inaccessible to transcriptional machinery
during the process of mitosis (condense in prophase, decondense in telophase)

Question 9

Chromosome vs Chromatid

Answer 9

A chromosome is the condensed form of DNA which is visible during mitosis (via microscopy)

As the DNA is replicated during the S phase of interphase, the chromosome will initially contain two identical DNA strands

These genetically identical strands are called sister chromatids and are held together by a central region called the centromere

When these chromatids separate during mitosis, they become independent chromosomes, each made of a single DNA strand

Question 10

Mitosis

Answer 10

the process of nuclear division, whereby duplicated DNA molecules are arranged into two separate nuclei

Question 11

Four stages of mitosis

Answer 11

prophase, metaphase, anaphase, telophase

Question 12

Before mitosis

Answer 12

Interphase:

DNA is present as uncondensed chromatin
DNA is contained within a nucleus
Centrosomes and other organelles have been duplicated
Cell is enlarged in preparation for division

Question 13

Prophase

Answer 13

spindle microtubules are growing
chromosomes are becoming shorter and fatter by supercoiling
each chromosome consists fo two identical chromatids formed by DNA replication in interphase and held together by a centromere
spindle microtubules extend from each pole to the equator

Question 14

Metaphase

Answer 14

the nuclear membrane has broken down and chromosomes have moved to the equator
spindle microtubules from both poles are attached to each centromere, on opposite sides

Question 15

Anaphase

Answer 15

the centromeres divide to allow sister chromatids to separate
spindle microtubules pull the genetically identical chromosomes to opposite poles

Question 16

Telophase

Answer 16

all chromosomes have reached the poles and nuclear membranes form around them
spindle microtubules break down
chromosomes uncoil and are no longer visible
the cell divides with genetically identical nuclei