Cell Cycle, Mitosis, and Cancer

Question 1

WHAT IS THE CELL CYCLE?

Answer 1

It is born, it grows,
reproduces and dies

It is divided into two stages:

GROWTH STAGE
(INTERPHASE)

DIVISION STAGE
(MITOSIS AND CYTOKINESIS)

Question 2

DESCRIBE INTERPHASE

Answer 2

The cell spends almost 90% of its life growing

Cell grows and carries out its normal functions

Cell also makes copies of its organelles and DNA

Cell also makes mistakes and fixes them before cell
division starts

Question 3

FACTS ABOUT CELLS

Answer 3

Cells do not divide continuously.

Most of the life of a cell is spent in
interphase during which time
hundreds of specific functions are
performed:

Growth, obtaining energy,
synthesizing products like hormones,
repairing damage, and fighting disease.

Different types of cells spend
different lengths of time in the
phases of the cell cycle

Question 4

WHAT ARE THE STAGES OF INTERPHASE?

Answer 4

G1 (Growth) Phase:

the cell is growing and carrying out
metabolic activities

(eg. producing proteins)

S (Synthesis) Phase:

• the cell makes (synthesizes) an
  entire identical copy of its DNA

G2 (Growth) Phase:

- the cell moves into its second
growth phase where it approaches
its maximum size and produces the
structures needed for mitosis (cell
division)

Question 5

WHAT IS THE DIVISION STAGE?

Answer 5

Mitosis

• Contents of the cell
  divide equally
• Focus is on the
  chromosomes (DNA)
• form 2 new daughter
  cells

Cytokinesis

• Cytoplasm & organelles
  divide equally
• Cell separates into 2
  identical daughter
  cells

Question 6

WHAT PHASE DOES THE cell grow, create for organelle, and DNA is duplicated?

Answer 6

Interphase

Question 7

WHAT OCCURS IN PROPHASE?

Answer 7

Chromosomes coil
and thicken

2 sister chromatids
held together by a
centromere to make
1 chromosome

Nuclear Membrane
disappears

Centrioles start to
move to opposite
poles

Spindle fibres start
to form

Question 8

METAPHASE?

Answer 8

Centrioles are now located on
opposite poles

Spindle fibres attach to the
centromere and align chromosomes
at the centre of the cell

The centre is known as the:

Metaphase plate or Equatorial Plate

Question 9

ANAPHASE?

Answer 9

Chromosomes split

sister chromatids go
towards opposite
poles

Question 10

TELOPHASE?

Answer 10

Nuclear membrane forms around
the nucleus of each set

Chromosomes stretch out and
become thin (chromatin)

Question 11

CYTOKINESIS?

Answer 11

Cell membrane forms around each new cell

2 distinct daughter cells are formed

Chromosome are unraveled to resume Interphase

Question 12

CYTOKINESIS:

PLANTS VS. ANIMALS

Answer 12

Animal Cell

Cleavage Furrow
forms

Plant Cell

Cell plate forms

Question 13

CANCER

Answer 13

a group of diseases when
cells grow and divide out of
control

The DNA code in a cell has
changed (mutated), causing
one or more of the cell
cycle checkpoints to
fail.

The mutated cell and all its
daughter cells divide
uncontrollably

can be hereditary or caused
by environmental factors

Question 14

WHAT IS A TUMOUR?

Answer 14

a lump/mass of
uncontrollably
dividing cells that has
no function.

Can be

benign

malignant

Question 15

BENIGN TUMOR?

Answer 15

not cancerous

Cells stay in one place and do not seriously affect
surrounding tissues.

can become large enough that it
crowds/compresses surrounding tissues/organs
and affects their normal function.

Question 16

WHAT ARE MALIGNANT TUMOR?

Answer 16

Cancerous

If they grow into a
blood vessel they
can metastasize

cells of the tumour
can destroy or
interfere with the
function of
surrounding tissues

Question 17

WHAT IS METASTASIS

Answer 17

malignant cancerous cells break away from
“primary” tumour and travel to another part of the
body by way of the bloodstream

once settled, they will begin to divide uncontrollably
again, starting a new “secondary” tumour

cancer becomes extremely difficult to control
and can affect several parts of the body

Benign tumours by definition, do not metastasize

Question 18

CANCER IN THE LIVER?

Answer 18

The effect of
metastasis is clear in
this cross section of a
human liver.

The pale deposits are
tumours which have
spread throughout
the organ.

Question 19

SEVERITIES OF CANCER?

Answer 19

A mutation in a normal cell can lead to uncontrolled
cell division.

Cancer only develops if the resulting tumour is
malignant.

If metastasis occurs, the cancer becomes even more
dangerous.

Question 20

CAUSES OF CANCER?

Answer 20

Changes to the DNA code are
called mutations.

Mutations are the driving force of
evolution.

Very rare mutations may affect the DNA
that controls the cell cycle checkpoints.

If this occurs, the cell does not know
that it should stay in interphase.

Mitosis and cytokinesis occur until all
nutrients are exhausted.

Question 21

HEREDITARY CAUSES OF

CANCER?

Answer 21

DNA inherited
from previous
generations may
contain mutations
that can increase
risk of cancer

Examples include:

Some breast and
colon cancers

Question 22

WHAT ARE CARCINOGENS?

Answer 22

Carcinogens are environmental factors that can
mutate DNA and increase risk of cancer

Examples:

tobacco smoke

x-ray/UV radiation

some viruses

various chemicals

Question 23

PREVENTIONS OF CANCERs?

Answer 23

1. Do not smoke, or quit
2. Protect your skin from UVA and UVB rays from the sun. Do not go to tanning salons
3. Learn about self examinations for early detection of cancer. A doctor can advise you when additional screening tests are necessary
4. Regular exercise can prevent about one third of all cancers
5. Eat plenty of fruits and vegetables. Eat less red meat and high fat foods.

Question 24

HOW TO TREAT CANCER?

Answer 24

SURGERY
Advantage:

If caught early can remove the entire
tumour.

Disadvantage:

Recovery is painful

May not catch it in time to remove all
cancer cells

CHEMO
Advantage:

Effective for spreading cancers.

Disadvantage:

Toxic to healthy cells and can be
very debilitating and painful.

RADIATION
Advantage:

Kills cancer cells

Disadvantage:

Can damage healthy
cells too.