2. Biological Approach L.O. To discuss the main themes of the biological approach To revise(?) information about genes (genotypes and phenotypes) Brace yourselves – I am going to talk fast at you for the lesson!

3. Homework Complete P5 + 6 in your workbooks.

4. BRAIN FACTS weighs 1300 - 1400 g made up of about 100 billion neurons makes us who we are “the most complex living structure on the universe” Society for Neuroscience

5. How many brain cells do you think you have? A:1,000 B:1,000,000 C:1,000,000,000 D:1,000,000,000,000

6. If you were to join all your brain cells together, how far do you think they would stretch? A:From here to Durham B:From here to London C:From here to the moon D:From here to Australia

7. Which of the following buildings would be able to house a computer with the same capacity of your brain? A:The Empire State Building B:Your School C:The Metro Centre D:The Houses of Parliament

8. How much information do you think you are capable of storing in your brain? A:An Encyclopaedia B:A Computer C:The school library D:The world’s telephone exchange

9. What percentage of you body’s oxygen does your brain consume? A:10% B:25% C:50% D:75%

10. NATURE NURTURE DEBATE How much of ‘you’ do you think is due to what you have inherited from your parents or from your life experiences. NATURE is what we are born with NURTURE is what we experience

11. Neuroanatomy Biochemistry Genes 3 features of the approach 1. GENETIC INHERITENCE  characteristics inherited via genes 2. BIOCHEMISTRY  Chemical activity (neurotransmitters and hormones) 3. BRAIN STRUCTURE  What different parts of the brain do

12. w hat exactly do we inherit? Can we change our physical characteristics or are they fixed? Does having a Y chromosome make someone a man? GENETIC INHERITENCE Genotype The genes, or combination of chromosomes someone has for a particular characteristic. (XX, XY) bbGb Phenotype The characteristic that is displayed (physical, behavioural or psychological) BLUEGREEN

13. BIOCHEMISTRY Source: science photo library Neuronal cell bodies Synapses occur at the junctions Axons psychlotron.org.uk What are neurotransmitters and what do they do?

14. BRAIN STRUCTURE Genes: determine the structure of the brain determine the levels of hormones and neurotransmitters Tell the body how to function If we damage our brains how does that affect our behaviour? What if someone is born with brain defects?

15. METHODOLOGY WE WILL STUDY Scientific approach – Experiments – Brain scans – Animal experiments Non-experimental – Twin and adoption studies

16. BRAIN LATERALISATION What do the two sides of our brains control? Are there differences between male and female brains?

17. As you were growing up, how did you know you were a girl or a boy? Was it because you had a vagina or a penis? Or was it something more than your physiology? Some people feel that their minds and bodies don't quite match up. This feeling is commonly known as transsexualism - - a type of gender identity disorder.

18. ANIMAL EXPERIMENTS How ethical is it to use animals in research? Are animals the same as humans?

19. 2 x STUDIES IN DETAIL MONEY (1975) case study of David Reimer GOTTESMAN & SHIELDS (1966) schizophrenia twin study

20. PRACTICAL Experiment Mann- Whitney U Test the difference between gender

21. KEY ISSUE How ethical are transgender operations?

22. Use these websites to find the definitions and learn more about the role of synapses and neurons http://outreach.mcb.harvard.edu/animations/synaptic.s wf http://outreach.mcb.harvard.edu/animations/synaptic.s wf http://faculty.washington.edu/chudler/neurok.html http://learn.genetics.utah.edu/content/addiction/rewar d/madneuron.html

23. Revision of genes Note: You do not need to take any notes. This ppt will be on the system if you need to go back and revise. You will only need to be able to do the examples I ask of you.

24. Chromosomes and their genes are made of a molecule called DNA. DNA molecules carry the code that controls what cells are made of and what they do. DNA stands for deoxyribonucleic acid. Each chromosome is a very long molecule of tightly coiled DNA. Which part of a DNA molecule holds this information? What is DNA?

25. The structure of DNA

26. Proteins are made of long chains of amino acids. There are 20 different types of amino acid from which to make proteins. protein molecule 1 What happens if the amino acids are in a different order? Different combinations of amino acids make different proteins. What are proteins? protein molecule 2 amino acids

27. Phenotype and genotype The overall ‘characteristics’ of an organism depends on two things: The full set of genes of an organism is called its genotype. All the observable characteristics of an organism are called its phenotype. 1.its genes (inherited characteristics) 2.the effects of the environment in which it lives. An organism’s phenotype therefore depends on its genotype plus environmental effects. phenotype = genotype + environmental effects

28. Observing variation in humans As well as environmental factors such as climate and diet, humans are affected by education, culture and lifestyle. Because these factors change our phenotype, the effects of many environmental factors can be clearly seen. Scientists often use identical twins to study the effects of environmental factors. Although the twins are genetically identical, each one will have been shaped differently by their environment and experiences. For example, a bad diet may cause one twin to be larger and less healthy than the other twin.

29. Genetic causes of variation Sexual reproduction is the most important cause of genetic variation because it mixes up genetic material. At fertilization, any male gamete can combine with any female gamete. All these events occur randomly and create new combinations of genetic material. During meiosis, homologous chromosomes exchange genetic material. They then line up and separate in different ways, producing a large variety of different gametes. How does it do this?

30. Different versions of genes Chromosomes in a homologous pair contain the same type of genes that code for the same characteristics, such as eye colour. Each different version of a gene is called an allele. Each chromosome in the pair, however, may have a different version of the gene. For example, the version of a gene on one chromosome may code for brown eyes, whereas the version of the gene on the other chromosome may code for blue eyes. allele for brown eyes allele for blue eyes

31. Homozygous alleles If the alleles for a characteristic in a homologous pair are the same, the organism is said to be homozygous for that characteristic. What colour eyes will these homozygous pairs of alleles produce? allele for brown eyes allele for blue eyes

32. Heterozygous alleles The characteristic expressed by heterozygous alleles will depend on which allele is dominant and which allele is recessive. If the alleles for a characteristic in a homologous pair are different, the organism is said to be heterozygous for that characteristic. What colour eyes will this heterozygous pair of alleles produce? allele for brown eyes allele for blue eyes ?

33. Dominant or recessive? Dominant alleles are always expressed in a cell’s phenotype. Only one copy of the dominant allele needs to be inherited in order for it to be expressed. Dominant alleles (e.g. brown eyes) are represented by an upper case letter (e.g. ‘B’). The phenotype for a particular characteristic depends on which allele is dominant and which allele is recessive. Recessive alleles are only expressed in a cell’s phenotype if two copies of it are present. If only one copy is present, its effect is ‘masked’ by the dominant allele. Recessive alleles (e.g. blue eyes) are represented by a lower case letter (e.g. ‘b’).

34. What eye colour? The allele for brown eyes is dominant over the allele for blue eyes. The individual will have brown eyes, because the allele for brown eyes masks the allele for blue eyes. allele for brown eyes allele for blue eyes So, what colour will the eyes be of an individual who is heterozygous for eye colour?

35. Heterozygous cross

36. What are sex chromosomes? Humans cells contain one pair of sex chromosomes, which control gender. Males have one X and one Y chromosome (XY). Y chromosomes are very small and contain 78 genes, whereas X chromosomes are larger and contain a 900– 1,200 genes. Because females can only produce X gametes, it is the sperm that determine the sex of the offspring at fertilization. X chromosome Y chromosome Females have two X chromosomes (XX).

37. Boy or girl?

38. A boy or a girl?

39. In the first 6-8 weeks All foetuses have the same undeveloped sex organs. The original system can develop into both male or female sex organs. It is the presence or absence of a single gene (SRY gene) which will dictate the future development of the foetus as a male or a female. (Male) (Female)

40. Male development XY

41. Male development SRY gene produces a protein : Testis Determining Factor (TDF) TDF influences the development of the gonads, they become testis The testis produce testosterone Testosterone triggers the development of external male organs i.e. penis

42. Female development The absence of male hormone will result in the development of the Mullerian system into female sex organs

44. Puberty After around 10 years, the hypothalamus releases a hormone which affects the anterior pituitary gland and this causes the gonads to become active. They control the development of secondary sexual characteristics.

45. What are inherited diseases? Inherited diseases are diseases caused by faulty genetic material that is passed on to future generations. They are sometimes called genetic disorders. Mutations can be spontaneous or caused by exposure to mutagens such as radiation and certain chemicals. There are over 4,000 known inherited diseases, although the specific alleles involved are only known for 25% of them. Many inherited diseases are caused by mutations in DNA, resulting in faulty alleles that are not properly expressed.

46. What is Huntington’s disease? Huntington’s disease, sometimes called Huntington’s chorea, is a rare and fatal inherited disease of the central nervous system. Huntington’s disease is caused by a single dominant allele, which means that heterozygous individuals will develop the disease. Around 4,800 people in the UK have Huntington’s disease. The disease causes damage to brain cells, leading to a gradual loss of co-ordination, decline in mental ability and changes in personality.

47. The symptoms of Huntington’s disease Symptoms of Huntington’s disease usually begin to develop between the ages of 30 and 50, although they can appear earlier in rare occasions. lack of concentration and memory loss twitching, clumsiness and stumbling Early symptoms include: depression and mood changes Huntington’s disease is incurable, but medication can help to reduce the symptoms. However, as the disease progresses, the person’s co-ordination and movement becomes worse, and their mental abilities decline further.

48. How is Huntington’s disease diagnosed? Huntington’s disease is usually diagnosed from the physical symptoms of the patient and a family history of the disease. Why might this be useful for someone planning to have children? People with the Huntington’s disease allele generally develop the disease later in life, so they may unknowingly pass the allele on to their children before realizing that they have the disease. The diagnosis is confirmed by a blood test that detects the Huntington’s disease allele. This test can also be used in people who have yet to show symptoms but who have a family history of the disease.

49. The inheritance of Huntington’s disease

50. Patterns of inheritance: Huntington’s

51. What is Down’s syndrome? Down’s syndrome is a genetic disorder that occurs when a person inherits an extra copy of chromosome 21. People with Down’s syndrome often have characteristic physical features, learning disabilities and have a higher risk of certain medical conditions. In the UK, Down's syndrome affects about one in every 1,000 children born each year. The risk of having a child with Down’s syndrome increases with maternal age, especially over the age of 40.

52. How is Down’s syndrome diagnosed? During pregnancy, ultrasound and amniotic cell tests can be used to estimate the probability that a baby has Down’s syndrome. After the baby is born, the diagnosis can be confirmed by taking a blood or tissue sample, and observing the shape and number of chromosomes under a microscope. How would a scientist recognize Down's syndrome by looking at chromosome number? 12354 9810 1211 76 131415 161718 19202122 X

53. Down’s syndrome and trisomy 21

54. Maybe linked to certain mental disorders and behaviours? TBC…………………………