B2 5 Mitosis And Meiosis

Question 0

Why does mitosis happen?

Answer 0

Mitosis happens in order to produce more identical cells for growth, repair and replacement

Question 1

What is mitosis?

Answer 1

Mitosis is normal body cell division

Question 2

Describe the stages of mitosis

Answer 2

The normal body cell copies the genetic information producing four pairs of chromosomes. A division occurs producing 2 identical daughter cells.

Question 3

What is differentiation?

Answer 3

The process by which stem cells become specialised to carry out a particular task.

In many animals, the cells become specialised very early in life. For example: when a muscle cell divides by mitosis- it can only form more muscle cells.

In contrast, plant cells are able to differentiate all through their life. Undifferentiated cells are formed at active regions of the stems and roots. Mitosis takes place continuously.

Question 4

What is meiosis?

Answer 4

Cells in the reproductive organs divide by meiosis to form the gametes (sex cells)

Question 5

What happens in meiosis?

Answer 5

The genetic material is copied and then the cell divides twice NOT once like mitosis. Then, four gametes are formed by the division each with a single set of chromosomes.

Question 6

What is variation?

Answer 6

Variation is a difference in the genetic material of an individual in order to enhance survival.

Question 7

What can stem cells do?

Answer 7

Stem cells have the potential to treat previously incurable conditions. New nerve cells may be grown for people with brain disorders.

Scientists hope that the embryonic stem cells can be encouraged to grow into almost any different type of cell needed in the body. Some people believe that whole organs can also be grown from embryonic stem cells.

Question 8

Problems with stem cells

Answer 8

Come from aborted embryos Ethical issues Violation of human rights Progress is slow; too much time and money used Embryos can not give permission

Question 9

Benefits of stem cell research

Answer 9

One of the best ways to find cures for incurable conditions

Some embryos used come from infertility

Can be obtained by adult bone marrow Also obtained by the umbilical cord of the baby Can be used to grow new cells for transplants

Question 10

What are chromosomes?

Answer 10

Thread like structures which are made up of large molecules of DNA.

Question 11

What is a gene?

Answer 11

A gene is a small section of DNA which codes for a particular combination of amino acids that make proteins

Question 12

What is DNA fingerprinting?

Answer 12

The use of the unique patterns in DNA to identify people

Question 13

What is homozygous?

Answer 13

An individual with two identical alleles for a characteristic. Eg: DD or dd.

Question 14

What is heterozygous?

Answer 14

An individual with different alleles for a characteristic. Eg; Dd

Question 15

What is genotype?

Answer 15

The genetic make up of an individual

Question 16

What is phenotype?

Answer 16

The physical appearance of an individual Eg: dimples or no dimples.

Question 17

What is a carrier of a disease?

Answer 17

Someone who has the allele for a disease (recessive) but receives no symptoms of the disease.

Question 18

Benefits of genetic screening?

Answer 18

•Able to identify if two people should have a baby •Ability to identify a disease before major effects take place Eg: Huntington’s disease causes death to the middle age.

Question 19

Disadvantages of genetic screening?

Answer 19

•Costs a lot of money •Takes up a lot of time •A long waiting time to get screened

Question 20

Mitosis Diagram

Answer 20

Question 21

Meiosis Diagram

Answer 21

Question 22

Gregor Mendel and DNA:

Answer 22

Mendel was the first person to suggest separately inherited factors which we now call genes

Question 23

Polydactyly:

Answer 23

Babies born with extra fingers or toes

Most common form caused by a dominant allele

Question 24

Cystic Fibrosis:

Answer 24

Genetic disorder that affects many organs of the body

Organs become clogged up by thick, sticky mucus

Caused by a recessive allele so it needs to be inherited from both parents

Question 25

Simple Punnett Square:

Answer 25

Question 26

Huntington’s Disease:

Answer 26

Inherited through a dominant allele

Causes death in the middle age