2.2 - Cell division and stem cells

Question 1

What are chromosomes?

Answer 1

the structure made of DNA that codes for all the characteristics of an organism. Found in pairs in the nucleus of a cell and carry a linear arrangement of genes.

Question 2

What are genes?

Answer 2

Section of DNA that creates a code that makes a specific protein.

Question 3

What is Mitosis?

Answer 3

Is a type of cell division - when a cell divides each new cell produced has the same genetic information as one another.

Question 4

When is Mitosis needed?

Answer 4

When an organism needs to grow
When an organism needs to replace worn-out cells
When organism need to repair damaged tissue

Question 5

How many chromosomes are in a human body cell?

Answer 5

46 chromones (single) 23 pairs

Question 6

What is the process of Mitosis?

Answer 6

1) cells begin to divide
2) DNA replicates to form 2 copies of each chromosomes
3) The nuclear membrane breaks down. The chromosomes line up across the center of the cell
4) One set of chrom. is pulled to each end of the cell and the nucleus divides
5) The cytoplasm and cell membranes divide into 2 identical daughter cells.

Question 7

What is meant when a cell is cancerous?

Answer 7

when a cell begins to grow and divide uncontrollably. New cells are produced even if the body doesn’t need them.

Question 8

What is a tumor?

Answer 8

A lump of cells formed as a result of uncontrolled cell division

Question 9

What is a carcinogen?

Answer 9

A chemical or other agent that causes cancer. Carcinogens damage DNA which will cause mutations to occur. Several mutations are needed until you become cancerous - adults more likely than kids to get cancer

Question 10

What are some lifestyle factors that increase your risk of cancer?

Answer 10

Chemical carcinogens in cigarette smoke
Alcohol intake
Exposure to UV - ionise skin cells
Poor diet

Question 11

What is Meiosis?

Answer 11

Occurs for the formation of gametes in sexual reproduction

Question 12

What happens in sexual reproduction?

Answer 12

Nucleus of male gamete (sperm) fuses with the nucleus of female gamete (egg) producing a zygote

Question 13

How many chromosomes do human gametes contain?

Answer 13

23 chromosomes (single)

Question 14

What is the process of Meiosis?

Answer 14

1) parent cell
2) chromosomes make identical copies of themselves
3) similar chromosomes pair up
4) sections of DNA are swapped,
5) cells divide into 2 cells
6) cells and chrom. divide again into 4 daughter cells

Question 15

What happens in Meiosis?

Answer 15

Cells divide twice to form four genetically different gametes each with half a set of chromosomes (23 single - haploid cells)

Question 16

What are Stem Cells?

Answer 16

Cells in the early stages of development of an embryo . Cells have not yet undergone differentiation and are not yet specialised.

Question 17

Where else can stem cells be found other than Embryo?

Answer 17

Adults - bone marrow, brain, liver, blood…

Question 18

What diseases can be treated by stem cells?

Answer 18

type 1 diabetes
multiple sclerosis
Spinal chord or brain injury

Question 19

Where is the best of source of stem cells?

Answer 19

5 day year-old Embryo

Question 20

What are the benefits of using your own stem cells?

Answer 20

No rejection
No need to find donor
No need for tissue typing

Question 21

What are the clinical issues with stem cells?

Answer 21

No guarantee for success
Difficult to find a donor
Mutations could occur
Hard to store

Question 22

What are the ethical issues with stem cells?

Answer 22

Is it right to create Embryos only to destroy them.

What stage of Embryo should it be classed as human.

Question 23

What are the social issues with stem cells?

Answer 23

Do benefits out weigh the risks

Possible false hope for cure after treatment

Question 24

Where does cell division occur in a plant?

Answer 24

Meristem - region in a plants shoots and roots.

Question 25

Cells of the meristem can ________ to produce all types of plant cells

Answer 25

Differentiate