UNDERSTANDING HEREDITY GENETICS AND MUTATIONS 1 Genetics Part

UNDERSTANDING HEREDITY GENETICS AND MUTATIONS 1

Genetics Part One 2

Genetics is… OThe scientific study of heredity 3

A gene is… OA sequence of DNA that codes for a protein and determines traits 4

What is an allele? OOne of two or more alternative forms of a gene that are found at the same place on a chromosome. 5

What does the term heterozygous mean? OThe organism has two different alleles for a trait. OExample: Tt Bb 6

What does the term homozygous mean? OThe organism has two of the same alleles for a trait. OExample: TT or tt BB or bb 7

OComplete section determining heterozygous or homozygous genotypes 8

What is a genotype? OThe actual genetic makeup of an organism. 9

What is a phenotype? OThe physical characteristics of an organism. 10

OComplete section on phenotype/genotype 11

Who was Gregor Mendel? OThe “Father” of genetics 12

What was his contribution? O His experiments laid the foundation of the science of genetics. O He noticed that traits could disappear in one generation and reappear in later generations. 13

Gregol Mendel July 20, 1822 Born Heinzendorf bei Odrau, Austrian Empire (now Hynčice, Czech Republic) January 6, 1884 (aged 61) Died Brno (Brünn), Austria-Hungary (now Czech Republic) e of Austria-Hungary Empir Nationality Genetics Fields St Thomas's Abbey Institutions sity of Olomouc Univer mater Alma of University Vienna Creating the science of Known for genetics 14

OComplete section on monohybrid crosses ONow start “Practice with Crosses” 15

Genetics Part Two 16

Define Independent Assortment OIndependent segregation of genes during the formation of gametes. ORemember: Meiosis is the formation of gametes. 17

Define Law of Segregation OSeparation of alleles during gamete formation. OExample: 1 of 2 alleles for eye color will go to each sperm or egg 18

Define Co-dominant OBoth alleles of a gene contribute to the phenotype OExamples: Type AB blood; 1 blue eye and one green eye; speckled chickens 19

Define Incomplete Dominance O One allele cannot dominate another; the final phenotype is a blend of the 2 alleles O Example: cross a red carnation with a white carnation makes a pink carnation 20

Co-dominance Incomplete Dominance 21

ORedefine genotype and phenotype 22

Co-Dominance How many genotypes are there? OThree: How many phenotypes are there? OThree AA, BB, AB 23

OComplete examples of incomplete dominance. 24

Incomplete dominance How many genotypes are there? OThree: How many phenotypes are there? OThree RR-red rr-white Rr-pink 25

OComplete examples of co- dominance. 26

Genetics Part Three 27

Sex chromosomes What are the female sex chromosomes? OXX What are the male sex chromosomes? OXY 28

What does it mean for a trait to be sex-linked? OIt is carried on one of the sex chromosomes, most likely the X 29

Examples of sex-linked traits would be… OThe ability to see color (color blindness) OHaving a full head of hair (baldness) OBlood clotting properly (hemophilia) 30

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What is a di-hybrid cross? OA cross between two individuals with two different traits that you are studying OComplete examples and problems 32

Mutations 33

What is a mutation? OGenes code OProteins for… OMutations are… OMistakes in genetic code that affect the final protein 34

What is a point mutation? A mistake in one nitrogen base of an m. RNA codon 35

Types of point mutations: O Substitution – 1 nucleotide is switched for another Example: CAT GCA CAT GCG O Insertion or deletion – 1 nucleotide is inserted/deleted in sequence Example: CAT GCA CAT GAC A Example: CAT GCA CAT CA 36

Effects of point mutations O Substitution O Might have no effect O Insertions/deletions on/or will only effect one amino acid O Change how the sequence is read – called a frameshift mutation 37

epidermolysis bullosa 38

What is a chromosomal mutation? A change in the number or structure of chromosomes. 39

Types of chromosomal mutations O Deletion - entire gene(s) deleted O Duplication – an extra copy of gene(s) added O Inversion – segment of chromosome is flipped over and reversed in place O Translocation – segment of chromosome breaks off/relocates to another 40

Result of: Duplication Can be the result of: Inversion, deletion or translocation 41

When mutations go… Wrong Right O Disruption of O Source of genetic biological activities O Disability O Death variation O May allow some members of a species a better chance to survive 42

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