Who are we? Write a brief 2-3 sentences to describe why these people are important! Friedrich Miescher James Watson Francis Crick Rosalind Franklin Maurice Wilkins Oswald Avery Erwin Chargaf

What is Genetics????

DNA, Chromosomes and Genes

DNA Cells carry instructions in the nucleus These instructions are about the whole organism ( all your features) These instructions are carried on a chemical called DNA Deoxyribonucleic acid DNA is a double helix RNA is the messenger that takes the information outside the nucleus to be translated into proteins

DNA and RNA

DNA structure showing nucleotides phosphate backbone and H bonds

Chromosomes Chromosomes are lengths of DNA Humans have 46 chromosomes These are in homologous pairs ( 23 pairs) Homologous chromosomes have the instructions about the same features We have 2 sets of chromosomes so our cells are called diploid ( 2n) 1 set from Mum and 1 set from Dad All your genetic material is your genome

Our Chromosomes We have 22 pairs of autosomes We have 1 pair of sex chromosomes Male = XY Female = XX

DNA and chromosomes chromatid proteins DNA

Comparisons in size

Instructions 1. Add 25g NaCl to 80mL dishwashing liquid to make up the volume to 1L 2. Stir to dissolve the NaCl but try to avoid frothing 3. Add 100mL of the NaCl solution to a cut and mashed kiwifruit in a 250mL beaker 4. Incubate in a water bath for 15 mins 5. Filter the kiwifruit mixture until you get 4cm in a test tube 6. Run ice cold Meths slowly down the side of the test tube so that is forms a 1cm layer on top of the kiwifruit filtrate 7. At the interface of the 2 layers white DNA strands will form 8. Use a pipette or hook to extract these 9. Put onto a microscope slide 10. Stain with Bromothymol blue

Karyotype – chromosome map A Karyogram is a photo of chromosomes A replicated chromosome

Human Karyotype

Diagram of 1 set of chromosomes showing the sex chromosomes

Genes Genes are lengths of a chromosomes that have instructions for one feature Genes control your features A chromosomes is made up of many genes We have about 31,000 genes For any one feature there are different versions eg. brown, black, blonde for hair colour The different versions of a gene are called alleles

Genes - proteins

Genes to Proteins A triplet of bases codes for 1 amino acid A protein is made up of a long chain of amino acids

Your genes You have alleles for each feature ( one from each parent) If alleles are different usually only one shows up This is called the dominant allele The other allele is called recessive Your genes are called your Genotype Your features are called your Phenotype

Inheritance: How genes are passed on to offspring – genetic crosses When doing crosses we give genes alphabet letters eg. Brown eyes - dominant B Blue eyes - recessive b Each sex cell ( sperm and egg ) have only 1 allele for each feature eg. B or b The offspring have 2 alleles

More genetics terms Homozygous – 2 alleles the same eg. BB or bb Heterozygous – 2 different alleles eg. Bb

Mendel Gregor Johann Mendel is called the “father of genetics” He was an Austrian monk who did lots of experiments on peas for 12 years He studied how features were inherited He drew up crosses to predict the offspring of known parents He predicted ratios of inherited features and proposed the “laws of genetics”

wrinkled round Punnett square

Pedigree analysis Used for looking at family histories Used for working out Genotypes Whether traits are dominant or recessive, autosomal or sex-linked Genetic counselling

Pedigrees

Pedigree symbols

Sex-linked genes Some genes for features are found on one sex chromosome and not the other Most of these features are found on the X chromosome These are called sex-linked eg. Red-green colour blindness, haemophilia

Sex linked inheritance Haemophilia Bleeders disease where the blood does not clot properly

Types of genetics problems Punnet squares – predicting ratios of offspring Pedigrees – to work out genotypes Test crosses – to work out if a parent is homozygous or heterozygous for a particular feature ( trait)

Rules for doing genetic crosses Assign letter to the alleles Write the phenotype Write the genotype Write the gametes Draw up a Punnett square Work out the ratios Answer the question

NCEA information 1.9 5 Biological ideas relating to genetic variation are limited to concepts and processes connected with: • the continuity of life based on the inheritable nature of DNA • links between DNA and variation in phenotypes • variation in phenotypes as adaptive features. 6 Biological concepts and processes relating to the inheritable nature of DNA will be selected from: • the roles of DNA in both carrying instructions to the next generation and determining phenotype • the relationship between DNA, alleles, genes, and chromosomes • the way in which genotype determines phenotype • the way chromosomes exist as pairs so that individuals inherit two copies of each gene.

NCEA information 1.9 continued 7 Biological concepts and processes relating to variation in phenotype will be selected from: • the significance of an allele as an alternative version of a gene • the role of mutations in forming new alleles • the role of meiosis in generating gametes (students are not required to provide the names of the stages of meiosis) • the significance of sexual reproduction (in producing a new mix of alleles) • the patterns of inheritance involving simple monohybrid inheritance showing complete dominance, sex determination, possible genotypes, and phenotype ratios. 8 Biological concepts and processes relating to variation in phenotypes as adaptive features will be selected from: • inheritable and non-inheritable variations that exist within a group of living organisms • differing rates of survival by various members of a group may depend on their phenotype • the importance of variation within populations (population and species survival) in a changing environment such as pest infestation, disease, drought, or flood • the advantages and disadvantages of sexual reproduction. 9 The student must be familiar with the following genetic language and conventions: gene, allele, mutation, genotype, phenotype, gamete, zygote, dominant, recessive, homozygous, heterozygous, pure breeding, Punnett square, and pedigree chart.

NCEA questions