Slide 1

UNIT IV Genetics

Slide 2

Slide 3

I.Genetics A. Mendel father of genetics Inheritance traits carried on chromosomes Genes code for certain traits Alleles same gene, different trait

Slide 4

Slide 5

Slide 6

B. Principle of dominance dominant trait will express itself 1.Dominant traits expresses, shows up 2.Recessive traits will only show up if both recessive alleles are present

Slide 7

C. Genotype gene, code R = red & r = white 1. Homozygous dominant 2 dominant alleles (RR = purebred) 2. Homozygous recessive 2 recessive alleles (rr = purebred) 3. Heterozygous one dominant and one recessive allele (Rr = hybrid) D. Phenotype how genotype expresses itself, looks like

Slide 8

Slide 9

Slide 10

C.Punnett square prediction of pairing R = red, r = white Genotypes all Rr Phenotypes all red RR x rrR Rr Rr Rr r r R = red, r = white Genotypes 1 RR, 2 Rr, 1 rr Phenotypes 3 red, 1 white Rr x Rr RR Rr rr R r RrRr Heterozygous(hybrid) cross

Slide 11

D.Incomplete dominance heterozygous blending of dominant and recessive trait Genotypes all Rr phenotypes all pink RR x rr 1RR = red, 2Rr = pink, 1 rr = white 2 pink and 2 white Rr R r RRRr rr R r RrRr rr Rrrr R r r

Slide 12

E.Codominance if heterozygous, both traits are expressed Blood types : antigens A, B, AB, O AB blood - both A and B antigens are present Positive blood is a separate gene Rh d antigen

Slide 13

F.Multiple alleles traits expressed on more than two alleles 1.3 or more alleles combinations of alleles genotype AABBCCDD whats the phenotype 2.Human examples Hair color 3 alleles (9) Eye color 3 alleles (9) Skin color 8 alleles (64)

Slide 14

G.Polygenic system interaction of multiple genes, determines phenotype 1.Continuous variation full range of phenotypes 2.Discontinuous variation phenotype fall into a few well separated categories

Slide 15

H. Environmental Influence on gene expression 1. sun exposure, cold example: siamese cat and himalayan darker color on ears, face and paws

Slide 16

I. Principle of segregation 1.Gametes separation of alleles occurs during meiosis 2.Parental purebreds homozygous, dominant or recessive (RR x RR or rr x rr) P generation = RR x rr 3.First filial F1 generation, offspring of P generation, hybrids heterozygous Rr 4.Second filial F2 offspring of hybrid cross, phenotype ratio 3:1

Slide 17

J. Independent assortment Dihybrid cross TtGg x TtGg predicted phenotypes 9:3:3:1 T = tall t = dwarffill this in G = green g = albino

Slide 18

Punnett Square for BbEe sire bred to BbEe dam * Dam can contribute BEbEBebe Sire can contribute BEBBEEBbEEBBEeBbEe bEBbEEbbEEBbEebbEe BeBBEeBbEeBBeeBbee beBbEebbEeBbeebbee Being black, sire and dam must both be B-E-; having produced yellow and chocolate pups, each must also have the b and e alleles, so in each case the genotype is BbEe. A BbEe parent can contribute the four combinations of alleles BE, bE, Be, and be to various pups.

Slide 19

BBEE (1 pup in sixteen or 6.25%) black BbEE (2/16 or 12.5%) black BBEe (2/16 or 12.5%) black BbEe (4/16 or 25%) black bbEE (1/16 or 6.25%) chocolate bbEe (2/16 or 12.5%) chocolate BBee (1/16 or 6.25%) yellow Bbee (2/16 or 12.5%) yellow bbee (1/16 or 6.25%) yellow with brown nose and light eyes

Slide 20

II. Human genetics A. Karyotyping human chromosomes 1.Autosomal 22 pairs of somatic 2.Sex chromosomes 1 pair XX or XY

Slide 21

B.Pedigree genetic relationship in families http://www.zerobio.com/drag_gr11/pedigree/pe digree1.htm C.Abnormalities different from the norm D.Disease serious disorders or abnormalities caused by genes

Slide 22

Slide 23

III. Human genes A. Autosomal recessive inheritance must have both recessive alleles 1.Albinism aa, cant make melanin 2.Tay-sachs disease at 6 months develops spot on retina blindness, death 3.Cystic fibrosis most common 1/2500 children 4.Lactose intolerance dont have lactase 5.Sickle cell anemia red blood cells, sickle shaped so cant carry O 2 well and get stuck in capillaries

Slide 24

B.Autosomal dominant inheritance two dominant alleles or heterozygous 1.Darwin tubercle thickened rim of cartilage in ear 2.Achondroplasia dwarfism 3.Huntingtons disease manifests in 30s or 40s, loss of muscle control, loss of brain tissue 4.Polydactyly 6 fingers or toes

Slide 25

IV. Sex-linked human inheritance traits carried on the x chromosome A.Sex linked disorders XX normal female, X - X female carrier, X - X - afflicted female, X - Y afflicted male, XY normal male 1.Hemophilia bleeding disorder X - Y or X - X - 2. Colorblindness red- green blue, X - Y or X - X -

Slide 26

V. Incorrect chromosome number any number but 46 in humans (Down syndrome- 47) trisomy on the 21 st chromosome A.Disjunction abnormalities extra or too few, occurs in meiosis, can also result in some degree of mental retardation and increased risk of diseases and defects 1. Turners syndrome: XO 2. Klinefelter syndrome: XXY 3. Meta or super female: XXX 4. Jacob syndrome: XYY

Slide 27

Slide 28

VI. Gene Regulation in Eukaryotes Female cat cells inactivate one of two X chromosomes in every cell (producing a Barr body) Different patches of skin cells in a cat inactivate different X chromosomes Patches of fur growing from skin cells may differ in color if fur genes on X chromosomes differ

Slide 29

Slide 30

VII. Structural abberrations A.Deletions part of chromosome is missing, cri-du-chat syndrome #5, leukemia #21 B.Inversions part of chromosome is reversed C.Translocation part of one chromosome breaks off and attaches to another chromosome D.Duplications chromosome replicates genetic material it already has VIII.Genetic screening Ethical issues insurance

Slide 31

Slide 32

I.Chemical nature of genes A.Coding capacity genes carry codes produces traits in the organism B.Transformation A T G C Adenine Thymine Guanine Cytosine nucleotide code for all traits II.DNA deoxyribonucleic acid A.Base composition Chargaffs rule A T, T A, G C, C - G B.Double helix model 1953 by Watson and Crick nucleotides form rungs of ladder, phosphate and ribose (sides)

Slide 33

Slide 34

Slide 35

Slide 36

Slide 37

1.Purines 2 carbon ring, adenine and guanine 2.Pyrimidines single carbon ring, thymine and cytosine 3.Base pairing A T, G C III.DNA replication A.Template bases need to form a complimentary strand B.DNA polymerase enzyme which separates the base pairs separates the DNA molecules IV.Mutations Alteration of the bases

Slide 38

Slide 39

Slide 40

Slide 41

Slide 42

Slide 43

Slide 44

Slide 45

Slide 46

I.RNA ribonucleic acid one strand A.Composition C G, A U, cytosine, guanine, adenine, uracil B.Function carry DNA instructions to various cell parts C.Protein synthesis code for amino acid sequences

Slide 47

D.Messenger RNA mRNA, carries DNA instructions codons E. Transfer RNA tRNA, translate the code anticodons F. Ribosomal RNA rRNA, from code puts amino acids together to form proteins G. RNAi- interference RNA- destroys suspect codes such as viruses

Slide 48

Slide 49

RNA Intermediaries There are three types of RNA involved in protein synthesis Messenger RNA (mRNA) carries DNA gene information to the ribosome Transfer RNA (tRNA) brings amino acids to the ribosome Ribosomal RNA (rRNA) is part of the structure of ribosomes

Slide 50

Slide 51

Slide 52

Slide 53

Slide 54

II.Transcription mRNA carries the code DNA mRNAtRNAamino acidrRNA C GCG assemble T AUA aspartic acid amino G CGC acids A TAU make C GCG cysteine the G CGC protein (transcription) (translation) (codons) anticodons III.Translation tRNA translates the code IV. Protein synthesis rRNA makes the protein

Slide 55

Slide 56

Slide 57

Slide 58

I.Genetic engineering A.Recombination in nature 1.Mutations 2.Crossing over 3.Selective breeding B.Plasmids DNA bearing units (rings) that lie outside of bacterial chromosomes used to incorporate DNA sequences then clone

Slide 59

B.Restrictive Fragments 1.Restriction enzymes cut DNA at specific places looks for recognition sequence 2.Gel electrophoresis sizing DNA fragments D. DNA sequencing PCR polymerase chain reaction make millions of copies of DNA sequence

Slide 60

II.Gene manipulation patented mice, genes inserted into eggs of organisms A.Gene insertion edit the code, frost resistance, drought resistance, BT corn B.Genetic engineering of bacteria insert human DNA into bacteria, human insulin, HGH C.Cloning make an exact genetic copy, reproductive cloning = Dolly 1.Recombination DNA Polly, human DNA for factor IX inserted into sheep donor cell 2.Xenotransplantation transplanting of organs from one species to another

Slide 61

Slide 62

From bacteria (E. coli) and fungus, fruits and vegetables to animals, genetic manipulation is becoming more and more common in our society. In the US market now, 60-70% of the processed foods are genetically modified. In 2006, United States GMO crops reached just shy of 135 million acres, with the total global area exceeding 250 million acres! This is a short list of the genetically modified food crops that are grown in the US today: Corn Soy bean Sugar cane Tomatoes Potatoes Sweet peppers Bananas Strawberries Zucchini Pineapples Cocoa beans Yellow squash

Slide 63

III.New human genetics human genome project, 20,000genes 30,000 genes, 3 billion base pairs A.Genetic disease 1,112 disease related genes, 400 base pairs identified B.Genetic testing: ethical issues C.cloning vs. variety, D.diagnostics vs. treatment IV.Genetically modified foods Golden rice, bacteria + daffodil genes, makes beta carotene Vitamin A Bt corn & cotton bacteria produces insecticide Herbicide resistant soybeans Concerns: allergies, hybridize V. Stem Cells