1. DNA and Inheritance
Hayley Siddons

2. DNA What is DNA DNA is packaged into Chromosomes in the cell
Deoxyribonucleic Acid
The unit of inheritance for all living organisms
DNA is packaged into Chromosomes in the cell
To make it more compact to fit into the cell
Easy of replication and equal division of the DNA during cell division (reproduction)

4. Chromosomes in cells
Same species of organisms always have the same amount of chromosomes
Humans have 46
Fruit Fly have 8
Corn has 20
Human (female) Karyotype

5. Chromosomes which are not the sex
chromosomes are called Autosomes

6. Chromosomes in cells The X shape of the chromosome
is because during cell division
(only time you can see defined
Chromosomes down a
microscope) each chromosome
is duplicated and the pairs are
joined in the middle at the
centromere

7. Mitosis Video

8. Mitosis Cell duplication
1 parent cell into to 2 identical daughter cells
Stages of Mitosis
Interphase
Prophase
Metaphase
Anaphase
Telophase
cytokinesis

9. Cell in normal functioning mode.
Signal is given to enter into Mitosis
and the cell replicates its DNA

10. DNA condenses down into the X shape that we recognise as a chromosome
Nuclear membrane breaks down

11. Chromosomes line up in the middle of the cell (equator)

12. The X shape of the chromosomes gets pulled apart
One of the identical chromatids goes to one side (pole) of the cell
The other identical chromatid goes to the other side (pole) of the cell

13. Chromosomes are now on each side of the cell
Nuclear membranes start to form around each of the DNA/chromosome groups
Cells start forming cell membranes between the groups of DNA (looked pinched)

14. Cell membranes ‘pinch off’ in between the two nuclei
Forming 2 genetically identical daughter cells

15. Worksheet Activity

16. Making sex cells
Sex cells (sperm and eggs) have (and need to have) half the amount of chromosomes as the nuclei of all other cells
This is because when the sperm and egg cells combine during fertilisation the resulting cells (offspring) have the required amount of chromosomes and no more

17. Pg 59
Activity Pg 59

18. Meiosis Video

20. Meiosis 1
Separation of the ‘X’ shaped chromosome pairs (one from mum, one from dad)
Results in half the amount of genetic material (eg now 23 pairs)
Chromosomes get randomly separated, so will get a mixture of mum and dad chromosomes going into the 2 cells
Meiosis 2
Separation of the sister chromatids
1 cell going through meiosis results in 4 cells, all with half the amount of genetic material

21. Mitosis vs Meiosis Worksheet

24. Determining Sex of the offspring
In humans only 2 chromosomes of the 46 chromosomes contribute to determining the sex (gender) of the offspring
The other 22 pairs of chromosomes have no effect

27. Sex Determination
Activity Pg 61

28. Check Questions Pg 62

30. Extracting DNA Practical

31. DNA Deoxyribonucleic Acid DNA made up of
Sugar Phosphate Backbone
Nitrogen-containing substances called bases
Adenine (A)
Guanine (G)
Thymine (T)
Cytosine (C)
The 2 stands of DNA bind together through the bases – forming base pairs
A with T
G with C
This holds the DNA molecules in the well known double helix structure

32. DNA Strands A T G C T G C A Write the complementary strand

33. Genes
Organisms are different because the proteins in their cells are different
The DNA provided the information about which amino acids make up proteins
It is the arrangement of the base pairs (A-T, C-G) which will determine the type of protein made
Sections of DNA which ‘code’
for a protein are called Genes
Determines the organisms
characteristics

34. It is the sequence of the DNA bases which form the code
The DNA Code
If the two strands in the DNA molecule of DNA separated, part of the strand would look like this:
It is the sequence of the DNA bases which form the code
Any three of these bases form a triplet code for an amino acid.
Eg GAT codes for Aspartic Acid
TCG codes for Serine

35. The DNA Code With the 4 bases
4x4x4 = 64 triplets which can be coded
This is more than the 20 amino acids used by cells to make proteins
Many amino acids have more than one coding triplet

37. The DNA Code
Different sequences code for different amino acids, which make up different proteins
the number of amino acids in a protein can be less than a dozen and more than
Therefore a DNA molecule can code for thousands of different proteins

38. Pg 66

39. Animals which are classes as Albino are born without any skin or hair colouring This is because the gene in each cell does not produce any colour pigments Because there has been a detrimental alternation in the original gene which codes for colour pigmentation

40. Mutations
Are Alterations in genes or important parts of the DNA molecule
Depending on where the mutation is and how it effects the gene/gene products/proteins it can be bad/fatal for the organism or it can be good for the organism

41. AAT CAA CCT TCA AAT CCA CCT TCA Mutations
Can be either a single base change in the DNA
Or a whole deletion or insertion of a segment of DNA into the gene
Or a rearrangement of the DNA segments on chromosomes
Depending on the base change in a DNA sequence, you could just change one amino acid or you could change it into a stop codon and thus shorten the protein. Either one could have a drastic effect depending on where it is located in the protein
AAT CAA CCT TCA
Asparagine glutamine proline serine
AAT CCA CCT TCA
Asparagine proline proline serine

42. How do Mutations occur
Occur naturally through normal DNA replication processes
1 mutation in every 30 million bases
Very slow rate of mutation
Mutation rates can be increased by exposure to
High energy radiation
Nuclear radiation
X-rays
Chemicals
UV in sunlight

43. Pg 68

44. Genomes
A genome is an organism's complete set of DNA, including all of its genes. Each genome contains all of the information needed to build and maintain that organism.

45. Human Genome Project When did the Human Genome Project begin?
Who was involved in the Human Genome Project?
What is the Human Genome Project?
What was the first step of the Human Genome Project?
How has advances in technology aided the Human Genome Project?
What are the benefits of the Human Genome Project?
What problems could arise from the Human Genome Project?

46. Genotype vs Phenotype
An organism’s genotype is the set of genes that it carries.
An organism’s phenotype is all of its observable characteristics—which are influenced both by its genotype and by the environment.
A change in the environment also can affect the phenotype. Although we often think of flamingos as being pink, pinkness is not encoded into their genotype. The food they eat makes their phenotype white or pink.
For example, differences in the genotypes can produce different phenotypes. In these house cats, the genes for ear form are different, causing one of these cats to have normal ears and the other to have curled ears.

47. DNA detective work
Why can understanding a persons genome or even a large segment of their DNA be important:
1. Matching donor organs with recipients for transplants
2. Identifying suspects from DNA in evidence left at a crime scene
3. Exonerating people wrongly accused of crimes
4. Identifying victims in major accidents or natural disasters
5. Establishing paternity of a child

48. Check Questions Pg 72

50. Dominant vs Recessive Genes
Male
Female

51. The colour of the fish on the previous slide is controlled by a particular gene
The gene comes in 2 forms:
Codes for black
Codes for red
Alleles- Different versions of the same gene

52. Even though the parents have the gene for red as well as black, the parents are still black
This is because the black masks the red
The gene for the black colour is said to be the dominant gene
The gene for the red colour is said to be the recessive gene

53. Always use the first letter of the dominant gene
Homozygous (pure breed)
Two copies of the same allele
Heterozygous (hybrid)
Two different copies of the
same allele
Represents the dominant gene
Upper case
Preceeds the recessive gene
Represents the recessive gene (not r)
Lower case
Proceeds the dominant gene
Always use the first letter of the dominant gene
use the capital letter to represent the dominant allele
use the lowercase letter to represent the recessive allele

54. Predicting crosses
It is possible to predict the type of offspring produced when 2 organism mate
One of the easiest ways of predicting crosses is to use a Punnett square

55. Pedigrees
By studying family histories a pattern of inherited characteristics can be developed
This pattern can be seen on diagrams called pedigrees
Females
Males

56. Pedigrees can be used to work out the genotypes of individuals

57. X-linked genes
There are a number of genes on the X chromosome that have no equivalent on the Y chromosome
These genes are X-linked

58. The allele for normal colour vision is dominant
A female who has an allele for colour-deficient vision on one X chromosome and an allele for normal colour vision on the other, will have normal colour vision. However she is called a carrier because she carries the affected gene for colour deficient vision
A male who has an allele for colour-deficient vision on one X chromosome will be colour deficient

59. Incomplete Dominance
When you have two alleles which are neither dominant or recessive
Instead they results as a mixture or a blend of the characteristic

60. Blood type (phenotype)
Co-dominance
When both allele or gene copies are produced
Alleles A and B are co-dominant, allele o is recessive
Alleles (genotype)
Blood type (phenotype)
AA or Ao A
BB or Bo B AB oo O

61. Check Qs Pg 80-81

63. Genetics Problems worksheet (Summative)

64. Pedigree Worksheet

65. Review Qs Pg 83-84

66. TEST