I. Mutations- a change in the genetic material that produces a new trait that is caused by a mutagenic agent or mutagen. Mutagenic agents are factors in the environment that cause mutations; for example, radiation from sources such as cosmic rays, radon, X-rays, ultraviolet & radioactive or chemical such as benzene & formaldehyde.
A. Gene mutation- changes in the base sequence of a DNA molecule
1. A change in the DNA sequence will alter the message transcribed by the mRNA; therefore, not making the correct structure of the protein.
2. Point Mutation- a single nucleotide in a gene has been changeda. testis determining factor mutation from "Human Chromosome Lab"
B. Chromosomal mutation- changes in the chromosome
1. Translocation- is the transfer of a piece of chromosome to a nonhomologous chromosome
2. Inversion- piece of chromosome is inverted & the sequence of genes are reversed
3. Addition- breaking of a piece of chromosome & then attached to its homologus chromosome
4. Deletion- piece of chromosome breaks off
5. Nondisjunction- during meiosis, a pair of chromosomes do not separate & a gamete now has one more chromosome while the other has one less. The resulting zygote will have either 45 chromosomes or 47 chromosomes (Down Syndrome)
6. Polyploidy- found in plants in which cells have multiple of the normal number of chromosomes- 3n, 4nII. Human Genetic Diseases: [recessive diseases]
A. Sex-Linked Disorders
1. Hemophilia- blood is unable to clot because it lacks a certain protein that doesn't make blood clot.
2. Muscular Dystrophy
3. Color BlindnessB. Autosomal Genetic Disorders-[defective alleles on chromosomes]
1. Sickle Cell Anemia- RBC are sickle shaped which disables the blood cell to carry oxygen; in the hemoglobin molecule 1 polypeptide chain is 300 amino acids, at one point GAA which places glutamic acid, but in this disease GUA is present & places valine instead
2. Phenylketonuria (PKU)- an enzyme is missing for the normal breakdown of an phenylalanine (amino acid). Mental retardation
3. Tay-Sachs Disease- affects descendants of Eastern Europe, missing an enzyme for the breakdown of lipids & results in death
4. Cystic Fibrosis- caused by a recessive allele on chromosome 7 which cause glands to produce a lot of mucus & clog the lungs. There is no cure for this disease, only treatment.
5. Huntington's Disease- Every person has the allele for this fatal disease. Symptoms don't appear until 30 yrs. of age. Brain cells die.C. Chromosomal Disorders
1. Down's Syndrome- caused by nondisjunction which results in an extra copy of chromosome #21; hence, a downs patient has 3 chromosomes. results in mental retardation & physical abnormalities.
2. Turner's Syndrome- nondisjunction of sex chromosomes which affects sexual development. Caused by only 1 X chromosome; results in a female with underdeveloped sexual characteristics
3. Klinefelter's Syndrome-nondisjunction of sex chromosomes which affects sexual development. Caused by having 2 X's & a Y in each cell, which results in a male with underdeveloped sex organs.III. Detecting Genetic Disorders
A. Amniocentesis- removal of amniotic fluid from a pregnant female. The chromosomes of the fetus can be examined by a process of karyotyping and the genetic material can be studied for genetic problems. Can also determine sex of fetus.
B. Blood Screening-
IV. Genetic Engineering
A. Breeding Methods
1. Selection- mating living things with desirable traits so the offspring will have those traits
2. Inbreeding- mating of closely related living things to obtain desired results. Inbreeding can also cause recessive traits to show of which some are not desirable.
3. Outbreeding- breeding individuals not closely related. This introduces new beneficial alleles into a population-hybrid vigor.
4. Cloning- production of genetically identical offspringB. Gene Splicing (another form of breeding): A research team led by Stanley Cohen accomplished the first gene transfer from one bacterium to another in 1973. The gene made the bacterium E.coli resistant to the antibiotic streptomycin.
1. Series of techniques used to transfer genes from one organism to another. It involves recombinant DNA "new strand of DNA" (adding a piece of DNA to a different strand of DNA)
Play Jeopardy using Power Point on Genetics
1. How are giant strawberries produced? answer
2. What are petite yeasts? answer
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