Understanding Genetic Information: Genes, Chromosomes, DNA, and Inherited Traits

1. Key Area 2.4 Genetic information

2. Starter Activity: Discuss the following questions with your partner: What are genes? Where in your cells are your genes found? What chemical makes up your genes? What physical characteristics are controlled by your genes?

3. Variation Learning Intention: To learn about how genes control the physical appearance of an organism Success Criteria: Be able to define the terms chromosome, DNA, gene and variation Understand that physical characteristics are inherited from biological parents through sections of DNA

4. Family resemblance Members of the same family often look similar. Which parent do these children look more like? Why do members of the same family look similar? Humans, like all organisms, inherit characteristics from their parents. How are characteristics passed on? Characteristics pass on through reproduction.

5. Species A species is a group of organisms who can interbreed and produce offspring which are fertile (able to reproduce). All humans can interbreed so we are all the same species.

6. Some unusual examples • Some animals seem to be members of the same species but are not. • The animals may be able to interbreed and produce young, but the young are not able to reproduce. • Two examples are mules and ligers.

7. Horse Donkey X Mule = A mule is infertile, so horses and donkeys are not the same species.

8. X Tiger Lion = Liger (infertile)

9. Variation • Although the members of a species are very similar to one another, they are not identical. • Variation occurs among members of a species.

10. German Shepherd

11. Poodle

12. Labrador

13. Terrier Yorkshire

14. Rottweiller Border Collie

15. Variation • Variation – differences that exist among members of a species.

16. What is variation? Differences due to inherited and environmental factors that exist between members of a species.

17. Human Variation Examples of human variation include: Twig Video: Human Variation Shoe size Hair Colour Height Tongue rolling Hair Type Fingerprints Freckles Blood group Handspan Eye Colour Weight Handedness Heart Rate

18. Variation Learning Intention: To learn about how genes control the physical appearance of an organism Success Criteria: Understand that physical characteristics are inherited from biological parents through sections of DNA

19. Starter

20. Variation For some characteristics there are clear groups of individuals. • Tongue rolling- can or cannot • Blood group – A,B,AB or O • Fingerprint patterns – whorls, loops, arches • Shape of leaves on oak trees – lobes, no lobes • Colour of petals on a flower • Seed colour in peas – green, yellow, brown

21. NUMERACY Variation graphs For any variation where the data gives distinct groups, a bar chart or pie chart can be used.

22. Human Variation You will look at examples of variation within the class and construct a table.

23. Activity 1 Complete the table in your booklet identifying the characteristics of people in the class.

24. Choose two of these variations, and draw a bar chart for each.

25. Measured variation For some characteristics there are not clear groups of individuals. Instead there is a broad range of measured values. • Height of rowan trees • Weight of rabbits • Pulse rate in humans • Leaf size in geraniums • Weight of chestnuts from tree • Height in humans

26. Range of heights and sizes

27. NUMERACY Variation graphs In this type of measured variation, most individuals have heights in the centre of the range, with few at the extremes. This type of graph is called a histogram or frequency graph.

28. Activity 2 Complete the table in your booklet showing the hand spans of people in the class. Then complete the summary table and histogram.

30. Structure of DNA and Genes

31. Genetic information Learning Intention: To learn about how genes control the physical appearance of an organism Success Criteria: Be able to define the terms chromosome, DNA, gene and variation Understand that physical characteristics are inherited from biological parents through sections of DNA

32. DNA stands for Deoxyribonucleic Acid. DNA is found in the nucleus of a cell. It is would up very tightly into structures called chromosomes. What is DNA?

33. Chromosomes • A chromosome is a threadlike structure that carries genetic information.

35. Gene

36. Genes • Chromosomes are split up into smaller segments called genes. • A gene is a section of a chromosome that contains a piece of genetic information e.g. the gene for tongue rolling. • We inherit half of our genes from our mother and half from our father. • This means that two genes control each characteristic.

37. How are genes inherited?

38. The parents Homer has straight hair Marge has curly hair

39. The families Is hair curliness controlled by genes or by the environment?

40. Homer • Homer has straight hair. • Every cell in Homer has two sets of genes. • Homer’s has two straight hair genes. • We can show the straight hair gene with a capital H. • Homer’s genes: HH.

41. Marge • Marge has curly hair. • Every cell in Marge has two sets of genes. • Marge has two curly hair genes. • We can show the straight hair gene with a small h. • Marge’s genes: hh

42. Making a new Simpson • Homer makes sperm. • Each sperm has one gene for hair type . • Homer only has straight hair genes. • So all of his sperm have straight hair genes. • Homer’s Sperm H H

43. Making a new Simpson • Marge makes eggs. • Each egg has one gene for hair type . • Marge only has curly hair genes. • So all of her eggs have curly hair genes. • Marge’s Eggs h h

44. Making a new Simpson This type of diagram is called a punnet square. Hh Hh H H Hh Hh h h

45. Making a new Simpson • All of the Simpson babies have one gene for curly hair and one gene for straight hair • So what type of hair do they have? Hh Hh Hh Hh

46. Making a new Simpson • THEY ALL HAVE STRAIGHT HAIR! • The straight hair gene is DOMINANT. • Just one copy of this gene will give you that characteristic. • The curly hair gene is RECESSIVE. • You need two copies of the gene to have that characteristic. Hh

47. Liking donuts • Homer likes donuts • Every cell in his body has two donut liking genes. • His genes are: D D • Homer’s sperm D D

48. Liking donuts • Marge doesn’t like donuts. • Every cell in her body has two donut disliking genes • Her genes are: d d • Marge’s Eggs d d

49. Making a new Simpson Dd Dd D D Dd Dd d d

50. Making a new Simpson • Liking donuts is dominant • Do the Simpson children like donuts? Dd Dd Dd Dd