Chapter 5: The Mitotic Cell Cycle

Question 1

Outline the 3 stages of the Cell Cycle and further break down each stage into smaller stages

Answer 1

1. Interphase
   a) G1
   b) Synthesis
   c) G2
2. Nuclear Division (Mitosis)
   a) Prophase
   b) Metaphase
   c) Anaphase
   d) Telophase
3. Cytokinesis

Question 2

Differentiate between Mitosis and Meiosis

Answer 2

1. Mitosis produces identical daughter cells; Meiosis products unique daughter cells
2. Mitosis produces 2 cells, Meiosis produces 4 cells
3. Mitosis is for somatic (body) cells; Meiosis is for gametes (sex) cells
4. Mitosis is 1 cell cycle; Meiosis is 2 cell cycles

Question 3

Checklist for the G1 phase

Answer 3

1. Nutrients
2. DNA damage
3. Cell size

Question 4

Checklist for G2 phase

Answer 4

1. Quality of replicated DNA
2. DNA damage
3. Cell size

Question 5

Differenciate between G1 and G2

Answer 5

1. G1 phase is longer than the G2 phase
2. G1: RNA and proteins are produced for cell’s day to day life; G2: Organelles are replicated and divide as well as spindle fibres begin to produce
3. G1 checks for Nutrients at its checkpoint while G2 checks for quality of DNA replication

Question 6

Define a chromosome

Answer 6

Supercoiled structure made from DNA and proteins (histone) found in the nucleus; condensed form of chromatin that carries the genetic information of the cell

Question 7

Differentiate between chromosomes, chromatin and chromatid

Answer 7

Chromosomes are the condensed form of chromatin that appear before cell division;

Chromatin is the pre-condensed form that chromosomes take during interphase;

Chromatids are either 1 of the 2 strands of a replicated chromosome that carries one DNA molecule

Question 8

Structure and function of Telomeres

Answer 8

Structure: Repeated nucleotide bases found at the ends of each sister chromatid

Function: Protects genetic information from being destroyed by the enzymes responsible for DNA replication

Question 9

State each letter of the Mnemonic for the functions of Mitosis

Answer 9

TOAD

T: Tissue repair // Cell Replacement

O: Organismal growth

A: Asexual reproduction

D: Development of embryos

Question 10

State the 4 stages of Mitosis and describe chromosome behaviour in each stage

*Practise your Naruto hand signals

Answer 10

1. PROPHASE: chromosomes appear
2. METAPHASE: chromosomes are brought to the middle of the cell
3. ANAPHASE: sister chromatids are pulled away from one another
4. TELOPHASE: chromosomes revert into chromatin

Question 11

State 2 characteristics of each stage of Mitosis

Answer 11

1. PROPHASE:
   a) DNA (with histones) supercoils into chromosomes
   b) Nuclear membrane begins to break down
   c) Paired centrosomes move apart to separate poles
2. METAPHASE:
   a) Microtubule spindle fibres connect to the kinetechores of each chromosome
   b) Spindle fibres contract slightly, to align chromosomes to the middle of the cell
3. ANAPHASE:
   a) Spindle fibres contract to split sister chromatids and pull them to opposing poles
   b) Each chromatid is now considered its own chromosome
4. TELOPHASE:
   a) Nuclear envelope reforms around chromosomes
   b) Mitotic spindle (centrioles) begin to disintegrate
   c) Cleavage furrow (in animals) begin to show; cytokinesis begins

Question 12

Differentiate between Animal and Plant cell cellular division

Answer 12

1. Animals form a cleavage furrow during cytokinesis while plants form a vesicle // cell plate
2. Animal cell separation is a CENTRIPEDAL force; Plant cell separations is a CENTRIFUGAL force
3. Plants cells do not have centrioles

Question 13

Define cancer

Answer 13

A disease wherein uncontrolled cellular division of abnormal cells occurs within the body

Question 14

Explain the terms “Metastasis” and “Oncogenes”

Answer 14

Metastasis is the spread of cancerous tissue from the originating tissue to other tissues // from one location to another.

Oncogenes are genes that have the potential to cause cancer.

Question 15

Describe the 2 kinds of tumors

Answer 15

1. Primary tumor: cancer that occurs in the originating tissue (benign growth)
2. Secondary tumor: cancer that occurs in neighbouring tissues (malignant growth)

Question 16

Describe the 2 kinds of oncogenes

Answer 16

1. Proto-oncogenes: genes that are responsible for the coding of proteins that promote cell growth and proliferation
2. Tumour suppression genes: genes that are responsible for proteins that repress cell cycle progression

Question 17

Describe the G0 phase

Answer 17

“Resting phase”

Stage of a cell cycle wherein the cell enters a state of rest, no longer preparing to divide or dividing. Often times specialized cells will enter the G0 phase and will only exit when there is a reason to divide.

Question 18

Differentiate between centrosome, centromeres, and centrioles

Answer 18

Centrosomes contain 2 centrioles and are considered the “Microtubule organizing center”. They separate during mitosis (moving towards opposing poles of the cell);

Centrioles are composed of 9 triplets of microtubules and aid in cellular division;

Centromeres are the region of chromosomes where the 2 chromatids are connected to

Question 19

Describe stem cells

Answer 19

“Undifferentiated” “Unspecialized” cells that have the potential to be any cell.

Self-Renewal: Capable of cellular division
Potency: Capable of becoming any cell

Used most of the time to replace damaged or diseased cells; can even become specialized cells.