chapter 10: stem cells & meristems part 1 – stem cells national 5 biology unit 2:...

Chapter 10: Stem Cells & MeristemsPART 1 – STEM CELLS

National 5 Biology

Unit 2: Multicellular Organisms

04/19/23 1Mrs Smith - National 5 Biology

Learning Intentions

National 5 Biology


By the end of this chapter, • You should be able to describe

that stem cells in animals can divide and have the potential to become different types of cell. Stem cells are involved in growth and repair• You should also investigate

the potential uses of stem cells and discuss ethical issues associated with their use.

Stem Cells: Introduction• It has been estimated that in

one day, you will shed about a million skin cells.

• These have to be replaced.• This requires a supply of new

cells as well as maintaining the original population of cells which gives rise to the new skin cells.

• The original population is made up of cells not yet committed but can form specialised skin cells.


Stem Cells: 3 features

• These uncommitted cells are called stem cells and are extremely important in animals.

• They have 3 important features1. They are UNSPECIALISED cells. Not yet committed to

being a particular type of cell.2. Reproduce themselves repeatedly (without limit) by

repeated mitosis and division during an animals lifetime.3. Divide to form two daughter cells. Each may still be

unspecialised or develop into various types of specialised cells when required, for example to replace cells that have come to the end of their life or have been damaged or lost.


Where are stem cells found?

Stem cells are found in different places in an animals body such as:

Bone marrow Teeth Lungs Heart Brain


There are two types of stem cells in animals

1.Embryonic stem cells 2.Tissue (Adult) stem cells


1. Embryonic stem cells

• An early human embryo contains EMBRYONIC STEM CELLS.

• These are capable of developing into all cell types found in the human body.

• They even have the potential to regenerate an entire organ from just a few cells.


1. Embryonic stem cells


2. Tissue (adult) stem cells

• A fully formed human possesses TISSUE STEM CELLS at various locations such as the bone marrow, blood and skin.

• These cells have a more limited potential than embryonic stem cells.

• Under natural conditions, tissue stem cells are only able to replenish the supply of one or more types of specialised cell closely related to the tissue in which they are found.


2. Example: Tissue (adult) stem cells

• Tissues stem cells in skin can only produce more skin cells.


2. Example: Tissue (adult) stem cells

• Tissue stem cells in red bone marrow can only give rise to new blood cells.


Potential uses of stem cells.

• Human stem cells can be grown in cultures provided that they are given optimum conditions and certain key growth factors.

• Stem cells have been put to use in some of the following ways 1. Bone marrow transplantation.2. Skin Graft3. Cornea Repair.

• We will look at these uses in more detail, but...• THERE ARE MANY OTHER WAYS TO USE STEM CELLS


MORE Potential Uses of stem cells.


Potential Uses of stem cells.1. Bone marrow transplantation.

• Some forms of cancer of the blood such as leukaemia result from the uncontrolled increase in the number of white blood cells.

• Once treatment involves destruction of the patients cancerous boneg s marrow cells and their replacement with a transplant of normal, blood forming stem cells from a suitable donor.


Potential Uses of stem cells.2. Traditional Skin Graft

• In a traditional skin graft, a relatively large section of skin is removed from a region of a persons body and grafted to the site of injury.

• This means that the person has two parts of their body that need careful treatment and time to heal.


Potential Uses of stem cells.2. Stem Cell Skin Graft

• A skin graft using stem cells only requires a small sample of skin to be taken to obtain stem cells.

• The site needs much less healing time and suffers minimum scarring.

• Because this technique uses the patients own cells there is no risk of the tissue being rejected.


2. Skin GraftSpray on stem cell skin graft

• A small sample of skin cells taken from an area close to, and similar in structure to, the site of injury.

• Enzymes are used to isolate and loosen the stem cells, these are then cultured.

• Once a suspension of new stem cells had developed, they are sprayed over the damaged area to bring about the regeneration of the missing skin.04/19/23 20Mrs Smith - National 5 Biology

Potential Uses of stem cells.1. Cornea (part of eye) repair.

• In recent years scientists have shown that corneal damage by chemical burning can be successfully treated using stem cell tissue.

• This can be grown from the patient’s own stem cells located at the edge of the cornea.

• Because this technique uses the patients own cells there is no risk of the tissue being rejected.


Potential Uses of stem cells.3. Cornea (part of eye) repair.


Future therapeutic potential of stem cells

• Embryonic stem cells are able to differentiate into any type of cell in the body.

• Because of this they could have the potential to provide treatments in the future for a wide range of disorders and regenerative conditions that current medicine cannot cure, e.g.– Diabetes, – Parkinson's disease.– Alzheimer's disease.– Multiple sclerosis.


Ethics

• Ethics refers to the moral values and rules that ought to govern human conduct (behaviour).

• The use of stem cells raises several ethical issues.


Stem cell research!

Stem cell research.


http://www.wired.com/images_blogs/photos/uncategorized/2009/03/25/fig3.jpg

Stem cell research controversy

04/19/23 Mrs Smith - National 5 Biology 26

The interplay between religion, ethics, legal issues, commercial interests and Government policies have made the stem cell research a very controversial topic

Ethics: Human embryonic stem cellsBall of cells vs Human being????

• At present , the creation of a continue of continuous embryonic stem cells (stem line) for research purposes makes use of cells take from a human embryo of no more than 14 days’ growth.

• Some people find this unethical because it results in the destruction of a human embryo (usually from ivf, the spare ones no-one needs)


Ethics: Human embryonic stem cellsInterspecies cocktail??????

• NUCLEAR TRANSFER TECHNIQUE.– The nucleus of the egg cell of one animal is

removed and replaced with that from another (donor cell).

– E.g Cow egg cell nucleus replaced with human skin cell nucleus. These cells are allowed to divide and are used for scientific research!

– This produces a hybrid (not 100% human), but can help research continue when there is a shortage of human embryonic cells.


Ethics: Should we use nuclear transfer to bring back the MAMMOTH????


Ethics: Should we use nuclear transfer..

What about a Neanderthal Man?????http://www.telegraph.co.uk/science/9814620/I-can-create-Neanderthal-baby-I-just-need-willing-woman.html


Debate Instructions• As you walked in the door you will be given a playing card Ace (1-4),

Spade(1-4), Diamond(1-4), Heart(1-4). This is important as your role in the debate will depend on this card.

• We will flip a coin. Heads means your group is in favour of the debate. Tales means they are against the idea.

• For Debate 1 (ACE AND SPADES) you will have an information sheet to help you with your arguments. – You have 15 minutes to prepare your argument then each group will have 5 minutes to present your argument.

• For Debate 2 (DIAMONDS AND HEARTS)listen to the podcast to help with your arguments. You have 15 minutes to prepare your argument then each group will have 5 minutes to present your argument.


Opening Statement Presenter: (1 min.) Gathers the main arguments into an

introductory statement. Does not give specific information; just says "this is true

because of A and B and C." -Topic Presenters: (3 min.)

Present the main arguments for the team. Each presenter gives specific details that prove A and B and C.

Closing Statement Presenter: (1 min.) Presents the closing arguments for the team. Repeats the main idea for this and this and this reasons.


Chapter 10: Stem Cells & MeristemsPART 2 – MERISTEMS

National 5 Biology

Unit 2: Multicellular Organisms


Learning Intentions

National 5 Biology


By the end of this chapter you should know• Meristems are the sites of production of non-

specialised cells in plants and are the sites for mitosis in a plant. These cells have the potential to become other types of plant cell and they contribute to plant growth.

• Be able to carry out practicals on root tip/shoot tip stain.

Meristems• Whereas most multi-cellular animals stop growing on reaching maturity, multi-

cellular plants continue to grow throughout their life.• Also growth in animals happens all over its body but in plants production of new cells

takes place only at areas called MERISTEMS.


Meristems are found at the tips of roots and the tips of shoots


Meristems

• Meristems are made of non-specialised cells that undergo continuous division.

• Some cells made are meristematic (can divide again producing more non-specialised cells that have the potential to become any type of plant cell).

• Others become elongated and then develop into specialised cells and tissues.


Meristems: APICAL and LATERAL

• Meristems consist of relatively small cells that can grow and mature to form new plant tissue.

• Meristems found at the tips of growing plants are called APICAL.

• Meristems found towards the outside of roots and are called LATERAL.


APICAL and LATERAL Meristems• Activity in apical meristems results in the

increased length of a root or shoots.• Activity in lateral meristems results in the

increased width of a root or shoot.


Apical meristems – root tips


TASK: Examining a stained root tip meristem to observe mitosis

• Mitosis is the cell process where cells divide into two.

• Mitosis involves many stages which ensure that the correct genetic information on chromosomes is contained within each daughter cell.

• View the root tip slides using a microscope and try to spot cells which are undergoing mitosis at the following stages:


TASK - Worksheet

• Now collect the root meristem worksheet and stick it into your jotter. Answer the questions.


Apical meristems – shoot tip

Meristems


TASK - Worksheet

• Now collect the shoot meristem worksheet and stick it into your jotter. Answer the questions.


1. What is a stem cell?2. State 3 features of a stem cell.3. Name two places in the human body where stem cells are

found.4. Which of the following statements are not true?

a. Stem cells cannot grow in large numbers.b. Growth takes place all over the body of a plant.c. Meristems can produce an increase in the width of a tree.d. During the lifetime of an animal, stem cells can divide repeatedly.

5. How does an apical meristem differ from a lateral meristem?6. Name two locations in a plant where a meristem would be

found.7. Give two differences between a meristematic cell and a xylem

vessel.04/19/23 46Mrs Smith - National 5 Biology

Glossary

• Stem cells• Unspecialised cell• Specialised cell• Embryonic Stem Cells• Ethical• Meristems• Apical Meristem• Lateral Meristem

• Nuclear transfer technique

• Tissue stem cells,• Hybrid• Mitosis


chapter 10: stem cells & meristems part 1 – stem cells national 5 biology unit 2:...

Documents

stem cells national

embryonic stem cells

types of stem cells

human stem cells

stem cells meristems

unspecialised cells

uncommitted cells

daughter cells