1. Genetics and Heredity

2. Gene-chromosome theory Genes are arranged in a linear sequence on chromosomes. Each gene has a definite position or locus The gene chromosome theory explains th hereditary pattern observed by Mendel. Every organism has at least 2 alleles that govern every trait Gene expression is the encoding of information that is expressed as the traits of an organism.

3. Gene expression Body cells contain the same genetic instructions – yet cells differ in structure and function. Genes that are on are expressed and genes that are off are not expressed What switches genes on and off? –Intracellular chemicals,enzymes, regulatory proteins, cell’s environment –genes can be inactivated depending on the needs of the cell at the time.

4. Genetic Mutations Mutations are changes in genetic material Mutations in body cells can be passed on to other body cells via mitosis Mutations in sex cells can be passed on to the next generation. Chromosomal alterations( number and structure) and gene mutations

5. Chromosomal alterations Changes in chromosomal number –Nondisjunction – one or more pairs of homologous chromosomes fails to separate normally during meiotic cell division. –Polyploidy – complete set of chromosomes fails to undergo disjunction – 3n,4n,5n. Inheritance of one or more complete extra sets. –Plants – larger, more vigorous – wheat, potatoes, alfalfa, apples, tobacco.

6. Chromosomal alterations Changes in chromosomal structure –Random breakage and recombination of chromosome parts –Translocation,addition,deletion,inversion Translocation- segment of one chromosome breaks off and reattaches to a nonhomologous chromosome Addition – segment breaks off one chromosome and reattaches to the homologous chromosome Deletion – segment breaks off and does not reattach to any other chromosome Inversion – segment breaks off and reattaches in reverse on the same chromosome

7. Gene Mutations Gene mutation is a random change in the chemical makeup of the DNA. Albinism is a gene mutation with noticeable affects Inheritable gene mutations tend to be harmful Sickle cell anemia, Tay sachs disease are caused by gene mutations. Usually involve one base change

8. Mutagenic agents Some mutations occur spontaneously Others caused by increased exposure to chemical agents Radiation – x-rays, ultraviolet rays, radioactive substances, cosmic rays, Chemicals include formaldehyde, benzene,asbestos fibers

9. Heredity and the environment Environmental factors – temperature, nutrients, sunlight can affect the development and expression of inherited traits. –Examples of gene action and environmental influences: Himalayan rabbits Chlorophyll and exposure to light Stress and nutrition – tallness and malnutrition

10. Plant and animal breeding Genetics allows breeders to be able to produce improve and maintain new varieties of plants and animals. Selective breeding – –artificial selection – individuals with the most desirable traits are crossed so hopefully offspring show these desirable traits. –inbreeding – mating of closely related organisms- selecting organisms to mate to produce organisms with those desirable traits –Hybridization – breeders cross two varieties each with desirable traits hoping to produce offspring showing both desirable traits – rose with large petals and sweet scent.

11. Human Heredity – pedigree charts Tracing patterns of inheritance in families use pedigree charts –Show presence or absence of traits in each generation –Helps identify carriers of recessive genes. –See lab practice

12. Human genetic disorders – detection and counseling Detection before or after birth Blood and urine tests – sickle cell anemia and Tay-sachs along with PKU. Karyotyping – photographs of homologous chromosomes show abnormalities in structure or number Anmiocentesis – amniotic fluid is used to karyotype or chemical analysis. Sickle cell, Tay-sachs and downs syndrome.

13. One gene one polypeptide hypothesis One gene controls the synthesis of a single polypeptide. A gene is a sequence of nucleotides in a DNA molecule necessary to synthesize one polypeptide. Jumping genes and transposons Gene mutations: change in the sequence of nucleotides in a DNA molecule.

14. Gene mutations Additions Deletions Substitutions

15. Cloning Genetic engineering Restriction enzymes Electrophoresis –See hand out – packet of review information