1.1

Question 1

What is a somatic cell?

Answer 1

a non-sex cell.

Question 2

What can a somatic cell make up?

Answer 2

They make up all the cells in the human body except from the reproductive cells (gametes). They also make up all the types of organs, skin, bones and blood.

Question 3

How many chromosomes do human somatic cells have?

Answer 3

46 (2 sets of 23 chromosmes)

Question 4

What is the chromosome complement for somatic cells?

Answer 4

somatic cells are diploid.

Some somatic cells can undergo mitosis, which gives rise to the number of daughter cells.

Question 5

By what process do somatic cells divide?

Answer 5

Mitosis

Question 6

What can increase due to somatic cells?

Answer 6

The size of the body and its organs can increase due to somatic cells.

Question 7

What are germline cells?

Answer 7

a cell that eventually leads to the formation of sex cells (gametes) - sex cells and stem cells that can divide to form gametes.

Question 8

What does a germline cell divide by?

Answer 8

The nucleus of a germline cell can divide by mitosis to help maintain the diploid chromosome number (23 pairs of homologous chromosomes). After mitosis, they are able to undergo a second form of nuclear division called meiosis.

Question 9

How many chromosomes do human gametes have?

Answer 9

23 chromosomes (1 set)

Question 10

Why is the maintenance of the chromsome complement important?

Answer 10

to ensure that no genetic information is lost or duplicated and that each daughter cell contains all of the charcateristics of its species.

Question 11

What are the 5 steps in mitosis?

Answer 11

Step 1 - the chromosomes in the nucleus shorten and bundle up. They can now be seen as pairs of chromatids. These chromatids are joined by a centromere.

Step 2 - the membrane of the nucleus is broken down and the pairs of chromatids are free to move.

Step 3 - spindle fibres attach to the centromeres that bind chromatids together. Once bound, they pull them towards the equator of the cell.

Step 4 - the spindle fibres contract and drag their sister chromatids apart from one another to opposite poles of the cell.

Step 5 - with the chromosomes at opposite sides of the cell, the cytoplams then divide, and two sister cells are formed.

Question 12

What are the three stages of meiosis?

Answer 12

Step 1 - copies of the genetic information are made.
Step 2 - the cell divides twice to form four gametes, each with a single set of chromosomes (haploid).
Step 3 - all gametes are gentically different from each other (they show variation).

Question 13

How many daughter cells are produced in meiosis?

Answer 13

4 daughter cells

Question 14

What is cellular differentiation?

Answer 14

a process which a cell expresses certain genes to produce proteins characteristics for that type of cell.

Question 15

What are the charcateristics for stem cells?

Answer 15

they are undifferentiated, found in all multicellular organisms, self-renewing and can differentiate.

Question 16

What are embryonic stem cells described as?

Answer 16

Pluripotent - a cell that is able to develop into many different types of cells or tissues in the body.

Question 17

What are tissue stem cells described as?

Answer 17

Multipotent - a cell that can develop into more than one cell type. but are more limited then pluripotent cells.

Question 18

What is the role of tissue stem cells in the body?

Answer 18

They are involved in growth, repair and maintenance of cells within a specific tissue.

Question 19

What are the therapeutic uses of stem cells?

Answer 19

corneal repair and regeneration of damaged skin (and bone marrow transplants)

Question 20

What are the research uses of stem cells?

Answer 20

model cells to study how diseases develop and are being used for drug testing. They also provide information on how cell processes, such as cell growth, differentiation and gene regulation work.

Question 21

Give 2 ethical questions that are used in the debate against the use of embryonic stem cells in research

Answer 21

1. As embryonic stem cells are obtained from early embryos, at what stage is the embryo regarded as a person?
2. Is it right to destroy embryos in the process of stem cell research?

Question 22

Give 3 clinical issues with using stem cells

Answer 22

1. stem cells are difficult to collect and store.
2. transplanted stem cells may carry mutations or viruses that could cause disease in patients.
3. stem cell therapy is still very new and therefore these therapies are not always successful.

Question 23

What are cancer cells?

Answer 23

Cells that do not respond to regulatory signals and therefore divide excessively.

Question 24

What is a tumour?

Answer 24

A tumour is a mass of abnormal cells that is formed from unregulated division of cancer cells.

Question 25

What happens if cells in a tumour fail to attach to each other?

Answer 25

The cells can break off from the tumour and spread to other locations in the body to form secondary tumours.