Genetics T H E S T U D Y O F H E R E D I T Y

Transcription

1 Genetics T H E S T U D Y O F H E R E D I T Y

2 Basic Vocabulary Genetics: The science of heredity Heredity The passing of physical characteristics (traits) from parents to offspring How does an organism pass on its traits? Where is the information for the traits found?

3 Location

4 Location The Nucleus Chromosomes Contains the genetic information Contains the blueprints for each trait Controls the expression of traits Are the genetic information Are long strands of DNA *Every cell has the exact same chromosomes and the exact same DNA.

5 Location Gene A section of a chromosome that controls a specific trait A gene controlling eye color A gene controlling your ability to curl your tongue (A Chromosome)

6 Gregor Johann Mendel ( ) The Father of Modern Genetics While living in a monastary, he observed the traits of pea plants. He noticed that pea plants showed either one or the other of these traits: 1. Round vs. Wrinkled 2. Yellow vs. Green 3. Long vs. Short

7 Mendel s Experiment 1. Cross pollinated pure tall plants with pure short plants. Pure Breed: When you mate a pure breed with another pure breed, all the offspring will be pure breeds as well. Hybrid: A mix of different traits Prentice Hall - Inc

8 Mendel s Experiment 1. The first generation (F1) all showed the tall trait. Prentice Hall - Inc

9 Mendel s Experiment 1. Mendel then cross pollinated the F1 generation with each other. Prentice Hall - Inc

10 Mendel s Experiment 1. Approximately 75% of the offspring were tall, and 25% of the offspring were short. Prentice Hall - Inc

11 Making Sense of Mendel s Results Alleles Different forms of the genes. Example: Tall stems vs. Short stems Law of Dominance When there are 2 different alleles, the dominant one will be expressed physically, the recessive one will not be expressed Although the recessive trait is not expressed, it may be expressed in the offspring of the individual

12 Making Sense of Mendel s Results Dominant Genes The gene you will see (that is expressed) Written with a capital letter T Tall Stemmed Plants Recessive Genes The gene you won t see if it s paired with a dominant gene Written with a lower case letter t Short Stemmed Plants Combinations of 2 genes (one from mom, one from dad) that will produce a: Tall Stemmed Plant Short Stemmed Plant TT Tt tt tt

13 Understanding Mendel s Experiment TT x tt Tt x Tt TT Tt Tt tt Prentice Hall - Inc

14 Understanding Mendel s Experiment Phenotype The trait you see TT x tt Genotype Tt x Tt TT Tt Tt tt The actual genes you have Prentice Hall - Inc

15 Understanding Mendel s Experiment Phenotype The trait you see TT x tt Genotype Tt x Tt TT Tt Tt tt The actual genes you have Prentice Hall - Inc 2 different genotypes can have the same phenotype.

16 Expression of Traits Genotype The genes an organism has. Ex TT, Tt, tt Phenotype The trait that is expressed (what it looks like) Ex Tall, Short

17 Gene Combinations Homozygous The traits for a gene are the same TT, tt Heterozygous The traits for a gene are different Tt

18 Predicting the Traits of Offspring Punnet Square Used to calculate the probability of the offsprings traits

19 Punnet Square of Mendel s Experiment P1: Pure Tall x Pure Short T T t t

20 Punnet Square of Mendel s Experiment P1: Pure Tall x Pure Short T T t t

21 Punnet Square of Mendel s Experiment P1: Pure Tall x Pure Short T T t t Genotype: TT: Tt: tt: Phenotype: Tall: Short: 0 % 100 % 0 % 100% 0%

22 Practice Punnet Squares You are have brown eyes, but are a carrier of a blue eye gene (hybrid). If you marry someone with blue eyes, what are the possible genotypes and phenotypes of your offspring? B Brown Eyes b Genotype: blue eyes BB: Bb: bb: Phenotype: Brown: Blue:

23 Practice Punnet Squares I have blue eyes. My parents and siblings all have brown eyes. How is this possible? Genotype: BB: Bb: bb: Phenotype: Brown: Blue:

24 When traits blend Incomplete Dominance When the genes are neither dominant or recessive. The two genes blend with each other Four-o clock flowers have genes for Red (R) and White (W) color. RR Red R R RR W RW WW White RW Pink (blended) W RW WW

25 Genetics of your Blood Codominance Genotypes: AA Ao BB Bo AB oo When there are more than one dominant gene. Human blood type has 2 dominant genes and one recessive gene A & B is dominant, o is recessive Phenotypes: A B AB oo

26 Genetics of your Blood A B Genotypes Phenotypes o o AA: Ao: BB: Bo: AB: oo: A: B: AB: oo:

27 Genetics of your Blood A o Genotypes Phenotypes B o AA: Ao: BB: Bo: AB: oo: A: B: AB: oo:

28 The Human Genome Karyotype A profile of an organism s chromosomes Organism # of Chromosomes Fruit Fly 8 Bread Mold (Neurospora) 14 Corn 20 Toad (Bufo americans) 22 Bean 22 Frog (Rana pipiens) 26 Cat 38 Rat 42 Rhesus Monkey 48 Sheep 54 Cattle 60 Horse 64 Goldfish 100

29 The Human Genome

30 Sex Linked Traits Sex Chromosomes The 23 rd Chromosome Pair Either XX (female) or XY(male) X X X XX XX Y XY XY 50% chance male 50% chance female The Y chromosome is shorter than the X chromsomes Sex linked traits are those found only on the X and not on the shorter Y chromosome

31 DNA Deoxyribonucleic Acid (DNA) Made of 4 different nucleic acids: A Adenosine T Thymine C Cytosine G Guanine Adenosine connects to Thymine: A T Cytosine connects to Guanine: C - G

32 DNA Match the following base pairs: A T A G C C A T C A A G G T A T C G G T A G T T C C

33 DNA Match the following base pairs: A T A G C C A T C A A G G

34 Types of Reproduction Asexual Reproduction 1 Parent Offspring are identical Mitosis Sexual Reproduction 2 Parents Offspring are a mixture of the parents genetics Meiosis Gamete Production (sex cells)

35 Types of Reproduction Mitosis Meiosis

36 Why 23 chromosomes and not 46? Male (sperm cell) 23 Female (egg cells)

37 Why 23 chromosomes and not 46? Male (sperm cell) Female (egg cells) Fertilization (Zygote) (Cell Division and Differentiation)

38 Inherited Diseases Hemophilia PKU (Phenylketonria) A blood clotting disorder Missing an enzyme made in the liver Cannot break down certain foods Chemicals build up in the body causing brain damage and death

39 Inherited Diseases Tay-Sachs Disease Sickle Cell Anemia Jewish children of eastern European ancestry Child s body does not produce an enzyme that breaks down fat Fat gathers in brain cells causing brain damage and death Affects people of African decent. Red blood cells are abnormally shaped Get trapped in blood vessels (clotting)

40 Applied Genetics Inbreeding crossing plants or animals that have the same or similar sets of genes, rather than different genes keep breeds pure problem? similarity causes organisms to be susceptible to diseases or to keep some undesirable traits (hip problems in dogs)

41 Applied Genetics Selective breeding Hybridization cross of plants or animals, with desirable characteristics, to produce offspring with those characteristics. crossing of two genetically different but related species of organisms. example: mule=female horse x male donkey

42 heritance/patterns/