higher human biology unit 1 – human cells. 1 division and differentiation in human cells cellular...

Higher human biology

Unit 1 – human cells

• 1 Division and differentiation in human cells • Cellular differentiation is the process by which a cell

develops more specialised functions by expressing the genes characteristic for that type of cell.

• (a) Stem cells — embryonic and tissue (adult) stem cells. • Stem cells are relatively unspecialised cells that can

continue to divide and can differentiate into specialised cells of one or more types. During embryological development the unspecialised cells of the early embryo differentiate into cells with specialised functions. Tissue (adult) stem cells replenish differentiated cells that need to be replaced and give rise to a more limited range of cell types.

Some questions to think about

• What is a cell?• What varieties of cell exist?• What is a tissue? Give some

examples.• What is an organ? Give some

examples.• What is a system? Give some

examples.

Bozeman biology

• https://www.youtube.com/watch?v=jp6L5emD8rw

Specialised cells

• The human body is made up of many specialised cells that have specific structural, functional and biochemical properties

• Specialised cells arise from the differentiation of unspecialised cells during embryo development.

• Specialised cells with similar functions are grouped into tissues. Similar tissues are grouped into organs and similar organs are grouped into systems.

Specialised cells

• https://www.twigonglow.com/films/different-types-of-cell-1042/

• Differentiation short film

Why have specialised cells?

• Division of Labour

• Multicellular organisms have millions of cells

• To ensure all process carried out – division of labour where cells become differentiated and specialised to carry out 1 specific function

•

• Cell differentiation is under genetic control and involves cell signalling processes.

• During differentiation, genes that express proteins important for the function of that cell remain ‘switched on’.

• Once a cell becomes specialised, it stops dividing and only expresses the genes are characteristic for that type of cell.

Differentiation

• During differentiation, certain genes that express proteins important for the function of a specific cell are ‘switched on’. This allows it to develop a more specialised structure to carry out a specific function.

• Once a cell becomes differentiated it only expresses the genes that produce the proteins characteristic for that type of cell.

Stem cells

Some questions to think about…

•What is a stem cell?•What are some different types of stem cells?•What is the purpose of stem cell research?•What are some ways that stem cells have been successfully used in medicine?•What are some of the issues in stem cell research?•What are some of the misconceptions that people have about stem cell research?

Stem cells film

• http://www.educationscotland.gov.uk/video/h/video_tcm4664297.asp?strReferringChannel=highersciences&strReferringPageID=tcm:4-665932-64&class=l3+d142456+d143862

What is a stem cell?

Identical stem cells

Stem cell

SELF-RENEWAL(copying)

Stem cell

Specialized cells

DIFFERENTIATION(specializing)

1 stem cell

Self renewal - maintains the stem cell pool

4 specialized cells

Differentiation - replaces dead or damagedcells throughout your life

Why self-renew AND differentiate?1 stem cell

Stem cell development animation

What are stem cells?Stem cells are unspecialised cells that have the ability to reproduce to make more stem cells or

differentiate into specialised cells of one or more types.

Stem cell jargon/definitionsPotency A measure of how many types of specialized cell a stem

cell can make

Stem cell Stem cell typetype DescriptionDescription ExamplesExamples

TotipotentTotipotent Each cell can develop into Each cell can develop into a new individuala new individual

Cells from early (1-3 Cells from early (1-3 days) embryos days) embryos (zygote)(zygote)

PluripotentPluripotent Cells can form any (over Cells can form any (over 200) cell types200) cell types

Some cells of Some cells of blastocyst (5 to 14 blastocyst (5 to 14 days)days)

MultipotentMultipotentCells differentiated, but can Cells differentiated, but can form a number of other form a number of other tissuestissues

Fetal tissue, cord Fetal tissue, cord blood, and adult stem blood, and adult stem cellscells

UnipotentUnipotent ????????Spermatogonial cells Spermatogonial cells in testicles only make in testicles only make spermsperm

Types of stem cells

Embryonic Adult

Embryonic stem cells

Embryonic stem cells

• Embryonic stem cells are derived from unspecialised cells found within an embryo.

• They have the ability to differentiate into all cell types that make up an organism.

Where are stem cells found?

embryonic stem cellsblastocyst - a very early

embryo about 50-100 cells

tissue stem cellsfetus, baby and throughout life

zygote stem cellsTotipotent can diffrerentiate into all cells and

placenta/ umbilical cord etc.

Adult (tissue) stem cells

• Do adult vs embryo stem cell card sort!

Adult (tissue) stem cells

• Adult or tissue stem cells are found in various tissues of adults and children, including the brain, bone marrow, skeletal muscle and skin.

• These cells replenish differentiated cells that need replaced through age or damage in the tissues in which they are found. They are able to differentiate into 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.

• Eg adult stem cells in bone marrow will produce red blood cells, platelets, phagocytes and lymphocytes.

Other types of stem cells

• Stem cells can also be taken from the umbilical cord of new babies.

• Like adult stem cells, these cells can differentiate into a limited range of specialised cells.

Induced pluripotent stem cells- the exception to the rule!

Induced pluripotent stem (iPS) cells are adult cells that have had their nucleus genetically reprogrammed to an embryonic stem cell-

like state.

• (b) Somatic cells divide by mitosis to form more somatic cells. These differentiate to form different body tissue types: epithelial, connective, muscle and nerve.

What do you think somatic cells are? Look at the pictures…..

B Lymphocyte

cartilage

Smooth muscle

Somatic cells

Ciliated epithelial cell

Red blood cellplatelets

neutrophil

Somatic cells

Cardiac muscle

Nerve cells

Squamous epithelial cells

T lymphocyte

Somatic cells

All body cells (except gametes and the cells which make them) are called somatic cells. They divide by mitosis and differentiate to form more cells of that tissue. Mutations that occur in somatic cells aren’t passed onto offspring.

• Do somatic cell passport activity

Tissues and organs

Body organs are formed from a variety of tissues made from somatic cells. E.g.

1. Epithelial cells which cover the body surface and line body cavities (E.g bladder, respiratory etc)

2. Connective tissue includes blood, bone and cartilage cells

3. Muscle cells form muscle tissue4. Nerve cells form nervous tissue

Give an account, with examples, of the different body tissue types and

their functions. (8 marks) 1. Body tissue cells derive from somatic stem cells …2. by repeated mitosis.3. Epithelial tissue - covers the organ surfaces.4. Protection - skin / secretion - intestinal glands / absorption - villi.5. Connective tissue - gives shape to organs and supports them.6. Protection - skull bones / structural framework - ribs / storage of energy -

adipose tissue / connecting body organs - blood / connecting epithelial to muscle tissue - cartilage (in tendons)

7. Muscle tissue - which causes locomotion or movement within organs.8. Skeletal muscle - locomotion / smooth muscle - in arterioles control of

access to capillary bed / cardiac muscle - contraction of the heart.9. Nervous tissue - which transmits messages between the central nervous

system and the rest of the body (and within the central nervous system).10. Neurons - conduct impulses / glial cells - maintain a constant

environment for neurons.

• (c) Germline cells divide by mitosis to produce more germline cells or by meiosis to produce haploid gametes. Mutations in germline cells are passed to offspring. Mutations in somatic cells are not passed to offspring.

What do you think germline cells are?

Division of germline cells• Germline cells can

divide by mitosis to produce more germline cells.

• Germline cells can divide by meiosis to produce gametes.

Germline cells

Gametes and the cells that produce the gametes are called germline cells. They divide either by mitosis to produce more germline cells or by meiosis to produce gametes.

Mutations that occur in germline cells are passed onto offspring

• Stage 1 – chromosomes copy themselves• Stage 4 – homologous pairs of

chromosomes line up at equator• Stage 5- chromosomes pulled apart by

spindle fibres• Stage 6 – 2 cells formed• Stage 8 – individual chromosomes line up

at equator• Stage 9 – chromosomes pulled apart by

spindle fibres• Stage 10 – gamete cells formed with half a

chromosome complement

Give an account of cell differentiation under the following

headings:

stem cells somatic cellsgermline cells

• (d) Research and therapeutic uses of stem cells by reference to the repair of damaged or diseased organs or tissues. Stem cells can also be used as model cells to study how diseases develop or for drug testing. The ethical issues of stem cell use and the regulation of their use.

Stem cell research

• http://www.educationscotland.gov.uk/video/h/video_tcm4664297.asp?strReferringChannel=highersciences&strReferringPageID=tcm:4-665932-64&class=l3+d142456+d143862

Therapeutic stem cells

• https://www.twigonglow.com/films/therapeutic-stem-cells-1066/

TED talk Anthony Atala Growing new organs

• http://www.ted.com/talks/anthony_atala_growing_organs_engineering_tissue?language=en

Stem cell researchStem cell research provides us with a wealth of information and can be studied in a variety of ways, including:

•how cell processes such as growth, differentiation and gene regulation work•the study of diseases and their development•drug testing•therapeutic uses in the treatment of diseases such as leukaemia (bone marrow transplant), Hunter’s disease and heart disease•therapeutic uses in medicine, including skin grafts for burns and stem cell grafts for cornea repair.

For example, stem cells could be turned into new bone cells and then injected into weak or broken bones to speed up healing time.

Windpipe Transplant

• http://www.bbc.co.uk/learningzone/clips/woman-gets-windpipe-transplant/5857.html

Or they could become nerve cells that could heal spinal cord injuries.

Skin cells could replace burnt skin, and brain cells could help people who have suffered brain damage.

Stem cells could be taken from someone with heart disease and be turned into heart cells, which can gather in a dish and throb! They could then be injected back into the patient to rebuild their heart tissue and combat heart disease.

• Beating heart cells in a dish! http://www.youtube.com/watch?v=RO4pAc21M24

• Symptoms: mask-like face, stiffness and tremors until sufferers eventually become immobile.

• Replacing the affected brain cells seems more hopeful than finding better drugs. Many people think that stem cells could be grown into new brain cells that could help to treat or even cure Parkinson's.

Therapeutic stem cell cloning

Stem cell uses

• Model cells to study how diseases develop

• Drug testing • Tissue replacement

– e.g. skin grafting for burn patients– heart tissue for heart disease patients– brain nerve cells for Parkinson’s sufferers– blood for transfusion– nerve cells for spinal cord injuries

• Do stem cell newspaper report activity

Corneal stem cell transplant

• https://www.youtube.com/watch?v=nHK0Lp1jJnw 2 mins

• https://www.youtube.com/watch?v=PJbdbAPXA7c 2 mins

• https://www.youtube.com/watch?v=eM9IzlK0uv8 25 mins

Corneal stem cell therapy

• Stem cells extracted from healthy eye, cultured (grown) and transplanted back into the damaged eye

• Repairs cornea• Shorter waiting time than traditional

donation• Reduced chance of rejection as

patient’s own cells transplanted

Describe how stem cells have contributed tocorneal transplants and skin grafts. 

• Corneal transplants 1. stem cells isolated from the patient's healthy eye2. new tissue can be cultured/grown3. transplanted back into the damaged eye,4. repair the damaged cornea.5. Shorter waiting time than corneal donation

• Skin grafts 6. Stem cells isolated from healthy skin7. New tissue grown / cultured8. dehydration and infection are risks until graft done.9. Produces skin cells much more quickly. 10. reduces the time patient at risk.

Presentation task

Using what you have learned already and adding further research, create a presentation that covers the following aspects of stem cells:

•the biology of stem cells – what is a stem cell, types of stem cells•the potential of stem cells – details of one or two research projects involving stem cells that you have found particularly interesting, details of potential therapies•stem cell dilemmas – explore the moral and ethical issues surrounding stem cell research (personal points of view can be expressed if desired).

You will be assessed using all three of the above criteria as well as on the overall quality of your presentation.

• www.sscn.co.uk• www.allthingsstemcell.com • www.hypeandhope.com• www.abpischools.org.uk click interactive, 14-16,

biology, then stem cell research• http://www.hhmi.org/biointeractive/click/

index.html• http://learn.genetics.utah.edu/content/stemcells/ • www.cells4life.co.uk

Criteria 4 3 2 1

The biology of stem cells Covers the topic in depth with details and examples. All key terms and words have been defined. Subject knowledge is excellent.

Includes essential knowledge about the topic. Subject knowledge is good.

Includes most information about the topic but there are some factual errors/omissions.

Content is minimal and there are several factual errors/omissions.

The potential of stem cells More than one example of stem cell research has been covered in depth. More than one example of potential stem cell therapies has been explored.

At least one example of stem cell research has been covered in depth. Potential stem cell therapies have been covered.

An example(s) has been covered but is lacking in depth and detail of information.

Examples are minimal. Very few details given.

Stem cell dilemmas The moral and ethical issues surrounding stem cell research have been explored in detail. More than one perspective has been given for many issues.

The moral and ethical issues surrounding stem cell research have been covered well. More than one perspective has been given for some issues.

Some moral and ethical issues have been mentioned but lack detail. Arguments detailed not balanced/only one perspective given.

Very little detail given in this area.

Quality of presentation Interesting, well rehearsed, all members of group involved, word content of slide minimal, good eye contact with audience, smooth delivery.

Relatively interesting, fairly smooth delivery. Eye contact mainly good and most members of group involved at some stage.

Able to maintain interest of audience but delivery not smooth. Failed to make eye contact on some occasions. Some group members not involved.

Poor eye contact, not able to maintain interest of audience. Reading from slides, delivery not smooth.

The ethical issues of stem cell use

http://www.playbackschools.org.uk/programme/3144/stem-cell-research-the-issue

(15min)

Stem cell views

• http://www.pbslearningmedia.org/resource/tdc02.sci.life.cell.stemcellvid/stem-cells-seeds-of-hope/#

Watch the clip on stem cell research and answer the following questions

http://www.pbslearningmedia.org/resource/tdc02.sci.life.cell.stemcellvid/stem-cells-seeds-of-hope/ (7min)

1. What does Dr Snyder mean when he says stem cells are "flexible and plastic?"

2. In this video what evidence convinces you that stem cells can be used to cure spinal cord injury?

3. Dr Snyder points out that there are ethical concerns, and that there is no single answer that will please everyone. Who do you think should be the ones to decide where to obtain stem cells for medical research?

• Do stem cell card sort for and against

Not in our back yard!

Should a business license be issued to ESC lifeworks Inc. by the city of Dundee?

Debate the issue- use the hand out to help organise the structure of the debate

Some useful Video Clips – Stem Cells and Ethics

• http://www.educationscotland.gov.uk/video/h/video_tcm4664297.asp?strReferringChannel=highersciences&strReferringPageID=tcm:4-658424-64&class=l3+d142456+d143862

• http://www.bbc.co.uk/learningzone/clips/stem-cell-research-and-medicine/6013.html

• http://www.bbc.co.uk/learningzone/clips/ethics-of-using-foetal-stem-cells-for-stroke-treatment/5888.html

• http://www.bbc.co.uk/learningzone/clips/alternative-to-embryo-stem-cells-developed-by-researchers/6581.html

• http://www.bbc.co.uk/programmes/p00k7j7w

• http://www.bbc.co.uk/learningzone/clips/stem-cell-research/14287.html

Ethical issues surrounding stem cells• Practices using adult (tissue) stem cells

remain fairly uncontroversial.

• Many pro-life and religious groups argue that embryos have human rights, should not be destroyed and should not be created simply for scientific research.

• Opposing arguments include the potential to discover cures for diseases for which there are currently none and improved treatment of a range of medical conditions.

Regulation of stem cell use

• The laws surrounding embryonic stem cells and adult stem cells differ because while both have similar capacities in differentiation, their modes of derivation are not.

• While embryonic stem cells are taken from embryos, adult cells can be taken from consenting adults.

Regulations surrounding the use of embryonic stem cells

– The research must be licensed by the Human Fertilisation and Embryology Authority (HFEA).

– Researchers must justify that the creation of an embryo is necessary and that the work could not be carried out in another way.

– Embryos over the development stage of 14 days cannot be used as this is the stage at which there is some primitive development of the nervous system.

• The use of stem cells in therapeutic treatments in the UK is currently restricted to adult stem cells.

• Whether or not embryonic stem cells can be used in the future remains to be seen.

Cloning

Cloning

• Human reproductive cloning is illegal in the UK. As a result of the Human Reproductive Cloning Act (2001) nobody in the UK is allowed to use cell nuclear transfer, or any other technique, to create a child.

Regulations surrounding stem cell use

• Research must be licensed by the Human Fertilisation and Embryology Authority (HFEA).

• Researchers must justify that the creation of an embryo is necessary and that the work could not be carried out in another way.

• Embryos must be under 14 days old.• Human cloning is illegal in the UK

Compare the location and functions of embryonic and tissue (adult)

stem cells. (7 marks) • Stem cells are undifferentiated cells capable of repeated division to both

more stem cells and cells that will later differentiate to form specialised cells.

• Embryonic stem cells (ESCs) are found in the inner cell mass of the blastocyst.

• ESCs are capable of repeated division…• …to form more ESCs and other cell types.• ESCs are: capable of forming all the other cell types of the body /

pluripotent• Tissue stem cells (TSCs) are found throughout the juvenile and adult

body.• TSCs are capable of repeated division to form more TSCs and other cell

types.• TSCs: can only form cells of the organ to which they belong / are

multipotent.• e.g. bone marrow tissue cells can only give rise to bone marrow cells, red

blood cells, platelets, phagocytes and lymphocytes.

• (e) Cancer cells divide excessively to produce a mass of abnormal cells (a tumour) that do not respond to regulatory signals and may fail to attach to each other. If the cancer cells fail to attach to each other they can spread through the body to form secondary tumours.

Stuart brown – stooibrown@yahoo.com

• Cancer.  I worked for ten years in the Dept of Surgical & Molecular Oncology at Ninewells so I can speak a bit about how cancer is researched and treated although there's not a lot I can say about pharmaceutical therapies - that stuff just went way over my head.  However, I can talk about the bowel cancer screening programme, for example and that might fit not just with this module but also with the public health bit later in the syllabus.  I also worked on x-ray ablation of breast cancer, cryogenic and thermal ablation of solid-organ cancers and a lot on colon cancer surgery.  Another thing I'm quite familiar with is the use of nanoparticles and microbubbles to pursue novel cancer therapies;

What is cancer?

• https://www.twigonglow.com/films/what-is-cancer-1580/

TED talk

• http://www.ted.com/talks/deborah_gordon_what_ants_teach_us_about_the_brain_cancer_and_the_internet

Reverse the odds app

• http://www.mavericktv.co.uk/news/emmy-nomination-for-reverse-the-odds/

Cancer cells•Cancer cells continue to reproduce to produce a mass of abnormal cells (a benign tumour).•They do not respond to normal regulatory signals that would instruct them to stop dividing when necessary.•They lose the molecules on their surface that would normally hold them in place and can therefore be detached from their neighbours, causing the cells to spread (malignant tumour).

Skin cancer cells (melanoma)

• It is thought that 90–95% of cancers are caused by environmental and lifestyle factors such as obesity and tobacco.

• It is estimated that 5–10% are due to genetics.

HPV – environmental factors

• Certain strains of the human papilloma virus (HPV) have been shown to cause cervical cancer.

• The routine immunisation programme in Scotland is for girls aged 12 and 13 (S2). There is also a one-off, three-year catch-up programme for older girls.

• Watch melanoma film

UV sensitive yeast

• UV sensitive strain of yeast: Baker’s yeast solution (saccharomyces cerevisiae) kept covered in foil.

• Yeast glucose agar dish divided into 3 sections: sun with sunscreen / sun with no sunscreen / no sun

• Use aseptic techniques• Expose to sunlight for 15 mins on bright day or longer on

less bright day (or UV light)• Incubate 3-4 days at room temp 1-2 days at 30 degrees.• Count the number of colonies

Cancer

• Cancer cells divide excessively to produce a mass of abnormal cells (called a tumour).

• They do not respond to regulatory signals that would instruct them to stop dividing when necessary.

• They may fail to attach to each other, called malignant tumours. This means they can spread throughout the body, forming secondary tumours.

Super Science: Nanotechnology

• https://www.youtube.com/watch?v=a8FM9umJXvo

• Imagine a tiny robot the size of a human cell, injected by the millions into your bloodstream on a search and destroy mission: to locate cancer cells, and kill them. Welcome to the scientific frontier of nanotechnology.

Your taskProduce an information leaflet designed to answer the questions of a patient recently diagnosed with cancer. Points to consider:

•How are cancer cells different from other cells?•What is a tumour?•How will I know if my cancer has spread?•What is the difference between a malignant tumour and a benign tumour?•How will my cancer be treated?