1.1 division and differentiation in human cells

Question 1

Define the term stem cells

Answer 1

Stem cells can divide to self-renew and can differentiate into specialised cells. They are present in both somatic and germline tissue

Question 2

State the difference between somatic and germline stem cells.

Answer 2

A somatic cell is any type of cell in the human body other than cells involved in reproduction where as germline cells are gametes

Question 3

Identify the two types of cell division

Answer 3

Mitosis- Cell division
Meiosis- Form of nuclear division which produces gametes

Question 4

State the types of cell division involved in the production of stem cells and haploid gametes

Answer 4

Somatic cells divide during growth and tissue repair (mitosis)
Diploid germline cells first divide by mitosis then by meiosis which further doubles the genetic material. The first round seperates the homolougus chromosomes and the second seperated the chromatids. The result is 4 haploid gametes

Question 5

Define the term cell differentiation

Answer 5

The process by which a cell expresses certain genes to produce proteins that are characteristic for that type of cell

Question 5

Explain how cell differentiation gives rise to specialised cells with particular functions

Answer 5

A human blood cell switches on the genes for the production of haemoglobin and a muscle cell switches on the genes for specific muscle proteins. This is called selective gene expression

Question 6

What do all differentiated cells originate from?

Answer 6

All differentiated cells with originate from unspecialised stem cells

Question 6

The two different types of stem cells are called

Answer 6

Embryonic, tissue

Question 7

Describe the role of embryonic stem cells

Answer 7

Embryonic stem cells have the ability to differentiate into all of the cell types that make up an organism

Question 8

What are embryonic stem cells described as

Answer 8

Pluripotent

Question 9

Describe the role of tissue cells

Answer 9

These cells replenish differentiated cells that need replaced in the tissues in which they are found.

Question 10

What do the tissue cells give rise too

Answer 10

These cells give rise to a much more limited range of cell types and will tend to develop into cell types that are closely related to the tissue in which they are found.

Question 11

What are tissue cells described as?

Answer 11

Multipotent

Question 12

Give examples of therapeutic uses of stem cells

Answer 12

Skin grafts- Used to treat people who are badly burnt

Bone marrow transplant- Used to treat people with blood related cancers, leukaemia or sickle cell anaemia

Cornea repair- Multipotent stem cells are removed from the healthy eye and transplanted into the damaged eye

Question 13

what does stem cell research involve

Answer 13

stem cell research involvs stem cells being used as model cells to study,
How diseases develop
How cells react when being tested with a variety of drugs

Question 14

State the difference between therapeutic and research uses of stem cells

Answer 14

The aim or research uses is to ensure that the quality of stem cells used and the safety procedures carried out are of the highest order and abuses of the system are prevented.

Therapeutic uses foucses on the medical potential and are in special interest of repair of diseased or damaged organs

Question 15

Identify some of the ethical issues of using embryonic stem cells

Answer 15

• Embryos need to be destroyed in order to gain access to them
  -Poses a moral dilemma between the duty to respect life and the duty to alleviate suffering by being able to treat disease and injury

Question 16

Explain why cancer cells divide excessively

Answer 16

A cancer is uncontrolled growth of cells. Cancer cells do not respond to regulatory signals

Question 17

State the term used t describe an abnormal mass of cells resulting from a cancerous cell

Answer 17

Tumour

Question 18

What can tumours be classified as?

Answer 18

Benign or malignant

Question 19

What is a benign tumour

Answer 19

A benign tumour is a discrete group of abnormal cells in one place within an otherwise normal tissue. For example warts which do not cause issues if removed

Question 20

What is a malignant tumour

Answer 20

Malignant is cancerous tumour. When some of its cells lose the surface molecules that keep them attached to the og group, enter the circulatory system and spread through the body.
This enables them to inade other tissues and do harm by producing new tumours in other parts of the body. This is how secondary cancer develops

Question 21

Explain why cancer cells may spread through the body

Answer 21

the surface molecules that keep them attached to the og group, enter the circulatory system and spread through the body.
This enables them to inade other tissues and do harm by producing new tumours in other parts of the body.

Question 22

Explain the difference between a primary and secondary tumour

Answer 22

Primary cancer is where a cancer starts. When cancer cells break away from the primary cancer and settel and grow in other parts of the body is when its then called seconary cancer

Question 23

what is a tissue

Answer 23

A living tissue is made from a group of cells witha similar structure and function which all work together to do a particular job

Question 24

Name the four basic types of human tissue

Answer 24

Epithelium
Connective tissue
Muscle tissue
Nervous tissue

Question 25

Epithelium

Answer 25

Covers the skin in an inner lining of digestive tract. Forms a physical barrier to damage and infection

Question 26

Connective tissue

Answer 26

Covers outer layers arteries, veins. Their elastic fibres give flexibility to blood vessels

Question 27

Muscle tissue

Answer 27

Skeletal muscles include fast and slow twitch fibres responsible for movement

Question 28

Nervous tissue

Answer 28

Involved in processing and communication within the body

Question 29

what do cancer cells originate from

Answer 29

Most cancers originate from a cell that has undergone a succession of mutations to the genes involved in the control of cell division.
As the genetic errors