Unit 1: Human cells: 1.1 Division and Differentiation in Human Cells

Question 1

What are somatic cells?

Answer 1

Any cell other than those involved in reproduction (gametes and the stem cells that produce them)

Question 2

How are new somatic cells be formed?

Answer 2

Somatic cells divide by MITOSIS to form new somatic cells

Question 3

Why do somatic cells divide?

Answer 3

Somatic cells divide during growth and repair to increase and maintain total cell numbers

Question 4

Are mutations passed down in somatic cells?

Answer 4

No, as they are non-germline cells so they do not pass on the mutation to offspring

Question 5

what is cellular differentiation?

Answer 5

Differentiation allows an unspecialised cell to BECOME another one of the specialised cells that make up the tissues in multicellular organisms. Cells EXPRESS certain genes to produce proteins characteristic for that type of cell, allowing them to carry out specific functions.

Question 6

How many pairs of homologous chromosomes do diploid cells have

Answer 6

Diploid cells have 23 pairs of homologous chromosomes

Question 7

what tissue types can somatic cells differentiate into?

Answer 7

Epithelial, connective, muscle, nerve

Question 8

During differentiation cells express certain genes to produce proteins characteristic for that type of cell, give an example of this

Answer 8

Red blood cells express haemoglobin gene to make haemoglobin to carry oxygen around the body

Question 9

Why is the maintenance of the chromosome complement important?

Answer 9

Important so that no genetic information is lost and that daughter cells have an identical copy of the genetic information of the parent cell

Question 10

What are Germline cells?

Answer 10

Germline cells are gametes(sperm and ova), and the stem cells that divide to produce gametes

Question 11

In humans where are germline cells found?

Answer 11

Germline cells are found in the testes and ovaries

Question 12

Describe the type(s) of cell division that Germline stem cells can do?

Answer 12

Germline stem cells are DIPLOID and can divide by MITOSIS or MEIOSIS.

Division by mitosis: the NUCLEUS of a germline stem cell can divide by MITOSIS to produce more GERMLINE(diploid) STEM CELLS

Division by meiosis: the NUCLEUS of a germline stem cells can divide by MEIOSIS to produce GAMETES(haploid) cells
-undergoes 2 divisions (first separating homologous chromosomes and secondly separating chromatids)

Question 13

What are stem cells?

Answer 13

Stem cells are cells that are UNSPECIALISED and have the ability to REPRODUCE(make copies of themselves) or DIFFERENTIATE (make other types of cells)

Question 14

Name the different types of stem cells

Answer 14

Embryonic and Tissue stem cells

Question 15

Where are embryonic stem cells found?

Answer 15

Embryonic stem cells are found a human blastocyst(very early human embryos)

Question 16

What is the meaning of the word “Pluripotent”?

Answer 16

Describes embryonic stem cells which can switch on all their genes so that they can differentiate into any type of cell

Question 17

What are tissue stem cells and what are they involved in?

Answer 17

Tissue stem cells are able to differentiate into all types of cells found in that particular tissue type, they are multipotent

Tissue stem cells are involved in growth, repair and renewal of the cells found in that tissue

Question 18

What are embryonic stem cells?

Answer 18

Embryonic stem cells are found a human blastocyst

They have the ability to switch on all their genes so they can differentiate into any type of cell, they are called pluripotent

Question 19

Describe what blood stem cells are able to differentiate into and why

Answer 19

Blood cells can differentiate into red blood cells, phagocytes, lymphocytes and platelets.

They are able to do this as they are tissue stem cells and therefore are multipoint- have the ability to differentiate into all types of cell found in that particular tissue type

Question 20

State the uses of stem cells

Answer 20

THERAPEUTIC
RESEARCH
EMBRYONIC

Question 21

How can stem cells be used therapeutically?

Answer 21

Stem cells used THERAPEUTICALLY involve the REPAIR of damaged or diseased organs or tissues.

e.g. stem cells can be used to PRODUCE healthy skin cells to help REPAIR damaged areas of tissue affected by burns/ acid attacks

Question 22

How may stem cells be used therapeutically to treat burns/acid attacks?

Answer 22

stem cells can be used to PRODUCE healthy skin cells to help REPAIR damaged areas of tissue affected by burns/ acid attacks

Question 23

How may stem cells be used for research? State 2 ways

Answer 23

Stem cells provide information on how CELL PROCESSES such as cell growth, differentiation and gene regulation work
Can also be used as MODEL CELLS to study how diseases develop or for drug testing

Question 24

How may embryonic stem cells be used?

Answer 24

They can self-renew under the right conditions, in the lab meaning they could be used to treat injury or disease

Question 25

What are the ethical issues involved with the use of embryonic stem cells?

Answer 25

Embryos cannot give CONSENT to their use- rather get stem cells from adults

An embryo is not a person although it has the POTENTIAL to develop into one

Question 26

What do some argue the use of embryonic stem cells is fair?

Answer 26

stem cell research uses embryos that were generated for IVF but were not used and would be DESTROYED

Before 14 days an embryo is not SENTIENT (i.e. doesn’t have consciousness or emotion)

Question 27

Describe cancer cells

Answer 27

Cancer cells divide EXCESSIVELY because they do not respond to REGULATORY SIGNALS

Question 28

What is a tumour?

Answer 28

After cancerous cells have divided excessively (due to not responding to regulatory signals), a MASS of ABNORMAL cells are formed called a TUMOUR

Question 29

What is metastasis?

Answer 29

Cells within a tumour may fail to attach to each other, spreading through the body where they form secondary tumours, known as metastasis