Module 2 - All cells arise from other cells

Question 1

What is the cell cycle?

Answer 1

A series of events hat occur during cell division as one parent cell divides to make 2 daughter cells

Question 2

What is mitosis?

Answer 2

The mechanism of cell division that occurs in cells called somatic cells diving one parent cell into 2 daughter cells

Question 3

What is the longest stage of the cell cycle and explain its function

Answer 3

Interphase. It has a gap 1 phase where the cell grows and makes a new set of organelles and proteins for the daughter cell. Synthesis stage where cellular DNA is replicated and daughter cells get one each. Finally gap2 phase where cell growth continues and there’s synthesis of special proteins

Question 4

What is the order of mitosis?

Answer 4

Interphase, prophase, metaphase, anaphase and telophase

Question 5

What happens in prophase?

Answer 5

Chromosomes condense as they become shorter and thicker therefore making the visually visible. Cells contain 2 organelles called centrioles that move to each pole. These contain spindle fibres that span across the cell forming a spindle apparatus. The nuclear envelope and nucleolus breaks down realising chromosomes into cytoplasm.

Question 6

What happens in Metaphase?

Answer 6

This is when chromosomes are now seen as 2 chromatids one of each containing DNA from each parent cell. This is when the spindle fibres attach to the centromere of the cell and pulls them along the spindle apparatus to form a line along the equator.

Question 7

What happens in Anaphase?

Answer 7

This is when the spindle fibres pull the 2 chromatids apart and pull them back to each pole of the cell. The energy is supplied from the mitochondria.

Question 8

What happens in Telophase?

Answer 8

Chromosomes now reach their receptive poles and appear as longer and thinner until they disappear completely. Nuclear envelope reforms so the cell now has 2 nucleus.

Question 9

What happens in cytokinesis?

Answer 9

Cytokinesis is where the cytoplasm splits forming 2 daughter cells. Each daughter cell is identical to the parent.

Question 10

What is mitosis important for?

Answer 10

Growth, repair and asexual reproduction

Question 11

What does it mean that plants don’t have centriole?

Answer 11

This means that spindle fibres will come straight from the cytoplasm.

Question 12

What is the process called that prokaryotes divide by?

Answer 12

Binary fussion

Question 13

How does the process of binary fusion work?

Answer 13

Circular DNA molecules replicate and attach to the cell membrane. Plasmids also replicate. Cell membrane grows between the 2 DNA molecules and begins to pinch inwards, dividing the cytoplasm into 2 dividing original cell into 2 identical daughter cells.

Question 14

What type of organisms are prokaryotes?

Answer 14

Unicellular organisms

Question 15

How do viruses replicate?

Answer 15

Attach to the host cell using the proteins on their surface. They inject host cells with nucleic acid containing ‘instructions’ on metabolic processes to start producing the viral components. These are then assembled into new proteins

Question 16

What are examples of viral components?

Answer 16

Nucleic acid, enzymes, structural proteins

Question 17

What is cancer?

Answer 17

Uncontrolled growth and the division of cells from a result of damage to genes that regulate mitosis and the cell cycle

Question 18

Where is a tumour most commonly found?

Answer 18

Breast (female), prostate gland (male) and lungs

Question 19

How does a tumour become cancerous?

Answer 19

If it changes from benign to malignant forming secondary tumours that travel through the blood stream.

Question 20

Malignant vs benign tumours

Answer 20

Malignant grow rapidly, are less compact and are more likely to be life-threatening. Benign is the opposite

Question 21

One treatment for cancer

Answer 21

Chemotherapy

Question 22

What happens in chemotherapy?

Answer 22

They disrupt the cell by preventing DNA from replicating and inhibiting the metaphase stage of mitosis by interfering with spindle formation.

Question 23

Why does chemotherapy cause hair loss?

Answer 23

Chemo targets cells that divide rapidly. Similar to other cells like hair-producing cells that divide rapidly, this will cause these cells to die meaning hair is likely to fall out.

Question 24

Mitosis required practical.

Answer 24

Heat 1mol dm^-3 HCL at 60 degrees in a water bath. Then use a scalpel to cut the root tip. Transfer sample to HCL and incubate for 5 mins then remove and wash in distilled water. Remove tip using scalpel. Place tip on microscope slide and use mounted needle to break open tip and add a few drops of stain. Carefully place down cover slip on slide. Place onto a microscope and set objective lens on lowest magnification. Use coarse adjustment lens to move lens down slid and use fine adjustment knob to re-adjust focus until image clear.

Question 25

What is the purpose of using stain?

Answer 25

Stain makes chromosomes visible therefore showing which cells are undergoing mitosis.

Question 26

What is the purpose of carefully placing the coverslip onto the slide?

Answer 26

Prevents air bubbles so no distortion to the image.

Question 27

What is the purpose of ensuring the cover slip doesn’t slide sideways?

Answer 27

This is to ensure that their is no damage to the chromosomes.

Question 28

How do we calculate mitotic index?

Answer 28

Number of cells undergoing mitosis/number of cells in total

Question 29

Risk assessment of HCL and using scalpel.

Answer 29

HCL = can cause irritation to eyes and skin. Wear googles and avoid skin contact. If contact then rinse/wash immediately. Low risk
Scalpel = can cause cuts. Use away from fingers and keep away from edge of desk. If cut apply pressure, seek medical assistance and evaluate cut. Low risk