1. Stem Cells
Noadswood Science, 2012

2. Stem Cells To understand chromosomes, genes and stem cells
Friday, April 21, 2017
To understand chromosomes, genes and stem cells

3. Key Terms
Complete the key terms worksheet

4. Key Terms

5. DNA
What is DNA?
DNA (deoxyribose nucleic acid) molecules are large and complex – they carry the genetic code that determines the characteristics of a living thing
Except for identical twins, each person’s DNA is unique allowing people to be identified using DNA fingerprinting
DNA can be cut up and separated, forming a sort of 'bar code' that is different from one person to the next

6. Gene What is a gene? A gene is a short section of DNA
Each gene codes for a specific protein by specifying the order in which amino acids must be joined together

7. Chromosomes
The cell’s nucleus contains chromosomes made from long DNA molecules

8. Allele
Some characteristics, such as eye colour and the shape of the earlobe, are controlled by a single gene
These genes may have different forms which are called alleles
Alleles are dominant or recessive…
The characteristic controlled by a dominant allele develops if the allele is present on one or both chromosomes in a pair
The characteristic controlled by a recessive allele develops only if the allele is present on both chromosomes in a pair

9. Chromosomes How many chromosomes do humans have?
A human nucleus contains 23 pairs of chromosomes – the 23rd pair determines sex (XX = female and XY = male)
Gametes only have 1 copy of each chromosome – this allows combing of the two sex cells from mother and father resulting in the correct number of chromosomes
Normal cell – 46 chromosomes (23 pairs)
Gametes – 23 chromosomes

10. Mitosis – Identical
First the cell makes a copy of each chromosome and then divides…
Each new cell has a full set of chromosomes and is identical to the original cell
Each new cell can keep on dividing by mitosis
Mitosis makes new cells for growth and repair in all living things – that’s how you get from one cell to 50 billion!

11. Mitosis

12. Mitosis

13. Meiosis – Single Set Of Chromosomes
First the cell makes a copy
of each chromosome followed by two stages of cell division…
Meiosis produces four new sex cells with half the original number of chromosomes
In animals, meiosis produces ova in females and sperm cells in males and in plants, the gametes produced by meiosis are pollen grains and ovules

14. Meiosis

15. Meiosis

16. Stem Cells
Embryonic stem cells can turn into any type of cell (they are undifferentiated and can develop into different types of cell depending upon the instructions they’re given)
Stem cells are found within human embryos (adults do have stem cells but they are only found in a few places such as bone marrow and are not as versatile as embryonic stem cells)

17. Stem Cells & Disease
Medicine has for many years used stem cells (e.g. sickle cell anaemia is treated by bone marrow transplants)
Embryos can have their stem cells extracted and grown specifically for medical purposes, such as…
To develop into heart muscle for heart disease
To develop into insulin producing cells for diabetes
To develop into nerve cells for paralysed individuals
The research remains in its infancy, but the possibilities for medical improvements are vast…

18. Negative Press
Some individuals are against stem cell research because they feel human embryos should not be used (as they can potentially become a human life)
The counter to this is stem cells can sure patients who already exist and are suffering already
Embryos used in research are normally unwanted ones from fertility clinics, which if they were not used for research would be destroyed…
Stem cell research is allowed in the UK, though it must adhere to strict guidelines