1. Wednesday, 07 November 2018
Exam Revision
Learning Objective: To be able to discuss and answer questions on HIV, Genetics and Excretion
Learning Outcomes:
Must know differences between bacteria and viruses (C)
Should Be able to complete a punnett square (B)
Could explain how the kidney works including labelling parts. (A/A*)

2. Starter

3. Bacteria on Roast Beef Green ‘blobs’ are Salmonella bacteria
Probably got on beef on the feet of a house fly
If it is left in a warm place, the bacteria will multiply
If you then ate it, the thousands of bacteria could make you very ill
X 2000

4. But HOW do microbes make us feel ill?
Think…
….Pair….
…..Share!

5. A disease causing micro-organism
What’s a pathogen?
A disease causing micro-organism

6. There are 2 main types of pathogen: Bacteria Viruses

7. Bacteria Cell Wall Cell Membrane Cytoplasm Chromosome NO true nucleus
Are very small cells
Reproduce rapidly in your body
Make you ill by- damaging cells and producing toxins
Bacteria
Cell Wall
Cell Membrane
Cytoplasm
Chromosome
NO true nucleus

8. Salmonella-food poisoning

9. NO true nucleus, NO cytoplasm
Viruses
Viruses are not cells.
They replicate themselves by invading your cells.
The cells burst and release the new viruses- this makes you feel ill!
Protein Coat
Genetic Material
Tail
NO true nucleus, NO cytoplasm

10. This is a picture taken with a microscope of a virus attacking a cell

11. How microbes make us feel ill
Bacteria
Viruses 1. T T T T 2.
T = toxin
Pupils have copy – label & write a sentence to describe/explain underneath 3.

12. Comparing sizes... You are the size of Europe
A fungus is the size of a football pitch
A bacteria would be the size of a bus
A virus would be the size of a football

13. Task
What is a pathogen?
Explain how bacteria and viruses cause disease.
Extension: Draw a labelled diagram of a bacteria and a virus
Bacteria
Virus

14. H I V & A I D S Virus Human Immunodeficiency Acquired Immune
Syndrome
More free powerpoints at

15. DRAW THE DIAGRAM!

16. Summary (HIV)
HIV is a virus
HIV works by infecting the cells of living organisms. (damaging the immune system)
The infected cells will then replicate (make copies).
The HIV then spreads.
People with HIV are known to be HIV positive.

17. Summary (AIDS)
When you have HIV your immune system is damaged, meaning your body struggles to fight off other infections (eg. AIDS).
Without medical treatment after about ten years the HIV will turn into AIDS.
Antiretroviral medication can slow down the time of change between HIV and AIDS.
AIDS is a killer virus and once diagnosed with it you are most likely to die very quickly.
There is no cure.

18. How is HIV passed on?
You can only be infected with HIV through another person with the virus. HIV is found in the blood and the sexual fluids of an infected person, and in the breast milk of an infected woman. Here are ways you can catch the virus:
Having unprotected sex with an infected person.
Close contact with an infected person’s blood.
Use of infected blood.
Mother to child - a mother with HIV giving birth to a child or a child drinking the mothers milk.

19. It is not possible to be infected with HIV through:
Sharing crockery and cutlery.
Insect/animal bites.
Touching, hugging or shaking hands.
Eating food prepared by someone with HIV.
Toilet seats.
Kissing
Kissing someone with HIV on the cheek does not pose any risk of you catching the disease. However ‘in mouth’ kissing does have a very low risk and there has been one incident. However, both of those peoples gums were bleeding.

20. Cures & Prevention
There is no actual cure for HIV & AIDS. However there are ways you can prevent yourself from catching the virus in the first place, or slowing down the transmission from HIV to AIDS.
You can prevent yourself from getting AIDS by using contraception when having sex with people who are HIV+ and not coming in close contact with their blood.
If you already have HIV you can use antiretroviral medication, which slows the progression from HIV to AIDS and keeps some people healthy for many years.

21. Africa
Approximately 95 percent of all AIDS orphans in the world live in sub-Saharan Africa.
Sub-Saharan Africa is the region of the world that is most affected by HIV & AIDS. An estimated 25.8 million people were living with HIV at the end of 2005 and approximately 3.1 million new infections occurred during that year. In just the past year the epidemic has claimed the lives of an estimated 2.4 million people in this region. More than twelve million children have been orphaned by AIDS.

22. Structure of Kidney Each kidney has four parts:
Cortex – the outer layer jammed pack full of filters called nephrons. Filters the blood.
Medulla – the middle layer which has the tubes carrying filtered wastes to the centre of the kidney. Contains Loop of Henle
Pelvis – area where all collecting ducts come together and connect with ureter.
Ureter – transports urine to the bladder.

23. Pelvis
Renal artery
Medulla
Renal vein
Ureter
Cortex

24. There are roughly one million nephrons in each kidney.
Cortex
Nephron
R. vein
Renal artery
Ureter
The unit of a kidney is the nephron – it carries out filtering and reabsorption.
Medulla

25. Blood is filtered in the renal capsule
Reabsorption of useful substances
Water levels of urine adjusted
To bladder

26. Blood arrives from the renal artery.
Glomerulus
Bowman’s capsule
Distal convoluted tubule
Blood arrives from the renal artery.
Blood enters a ball of capillaries called Glomerulus.
Theses capillaries sit in a filter called the Bowman’s or renal capsule.
Small molecules leave the capillary and enter the capsule – glucose, amino acids, salts, urea and water.
Capillaries off renal artery
Proximal convoluted tubule
Loop of Henle
Urine collecting duct

27. The filtered blood moves down the nephron.
Renal artery
The filtered blood moves down the nephron.
In the convoluted tubule cells reabsorb the good stuff – glucose, amino acids, most salt and water.
The rest – water and urea – moves on through the nephron.
Glomerulus
Bowman’s capsule
Distal convoluted tubule
Capillaries off renal artery
Convoluted or kidney tubule
Urine collecting duct

28. This adjusts water loss to suit the level of water in the body.
As the urine moves on more water is saved in the loop of Henle and collecting duct
This adjusts water loss to suit the level of water in the body.
Glomerulus
Bowman’s capsule
Convoluted tubule
Loop of Henle
Urine collecting duct

29. Renal artery
Glomerulus
Bowman’s capsule
Distal convoluted tubule
Capillaries off renal artery
Proximal convoluted tubule
Loop of Henle
Urine collecting duct

30. Renal artery: brings blood to the kidneys
Contains waste products.
Renal Vein: takes blood away from the kidneys. Purified blood
Convoluted Tubules: reabsorption of useful substances happens here; including Glucose, most water and some salts
Bowman’s Capsule: This is where filtration takes place. The filtrate contains useable & waste products
Collecting duct: collects urine from nephrons and transports it to the pelvis

31. Phenotype Genotype Allele Heterozygous Homozygous
physical appearance of an organism.
Phenotype
the set of genes (alleles) that an organism possesses
Genotype
Allele
different forms of the same gene
when the two alleles are different
Heterozygous
when two alleles (gene types) are identical
Homozygous

32. Dominant
allele which controls the characteristic whenever it is present.
BB or Bb
recessive
allele whose characteristics only show up when it is present on both chromosomes bb

33. PUNNET SQUARES
Meet Bob: Bob is confused He needs your help Bob has blue eyes Both of his parents have brown eyes How can Bob have blue eyes?

34. PUNNET SQUARES
Genes are on Chromosomes Chromosomes come in pairs… one from each parent Each chromosome contains genes Each gene will code for a particular characteristic Variations of the same gene are called Alleles (e.g brown/black hair; blue/green eyes)

35. PUNNET SQUARES
Some alleles will be DOMINANT over others… Eg Brown eyes B Other alleles will be recessive Eg Blue eyes b

36. PUNNET SQUARES
So when the egg that made Bob was fertilised, the chromosomes coding for eye colour joined… He could either have had BB = Brown eyes (Homozygous) bb = Blue eyes (Homozygous) Bb = Brown eyes still (Heterozygous)

37. PUNNET SQUARES
We need to think about what Bob’s Parents had as alleles for eye colour. Bobs Dad = Brown Eyes = Bobs Mum = Brown Eyes =

38. Punnet Square
Bobs Mum - B
Bobs Dad -

39. Punnet Square
Bobs Mum - B b
Bobs Dad -

40. Punnet Square
Bobs Mum - B b
Bobs Dad -

41. Punnet Square
Bobs Mum - B b
Bobs Dad-

42. Punnet Square
Bobs Mum - B b
Bobs Dad -

43. Punnet Square
Bobs Mum - b
Bobs Dad -

44. Questions 1. What is a dominant allele? 2. What is a recessive allele?
3. What does homozygous and heterozygous mean?
4. If a heterozygous man with dimples fathers a child with a woman with no dimples what is the probability of a child with dimples?