Biology Lecture Notes Unit 6-II.doc

Biology Lecture Notes Unit 6-II.doc - Unit 6 Evolution II...

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Unit 6 – Evolution II Biology Lecture Notes SECTION II - GENETICS AND HEREDITY A. The Biological Basis of Life I. Genetics a. Genetics is the study of how traits are transmitted from one generation to another. b. It is crucial to our understanding of disease processes, as well as our understanding of the process of evolution. II. What is a Gene? a. A gene is a sequence of DNA bases responsible for the synthesis of a protein. b. Different expressions of a gene are called alleles c. A change in the DNA sequence is called a mutation. III. Mutations - When a Gene Changes a. Mutations can occur in somatic and gamete cells 1) If they occur in somatic cells, they affect the individual 2) If they occur in gametes, they are passed on to offspring and have evolutionary consequences. IV. Review: Chromosomes a. Chromosomes are the structures that develop during cell division as DNA forms into tight coils. b. Humans have 46 chromosomes (gorillas and chimps have 48) c. Chromosomes generally occur in pairs d. There are two basic types of chromosomes, autosomes and sex chromosomes 1) Sex chromosomes are designated X and Y, with females resulting from an XX pairing, and males from an XY paring 2) The X chromosome also functions as an autosome, but the Y appears to have no function other than the determination of sex (this may be incorrect) 3) Any abnormal pairing of autosomes usually results in death soon after conception, while abnormal pairing of sex chromosomes usually results in sterility or other non-fatal consequences V. Review: Cell Division a. Mitosis – cell division in somatic cells and unicellular life forms 1) Results in identical diploid daughter cells b. Meiosis – or reduction division, is cell division that results in gametes 1) Results in haploid daughter cells ( i.e. , in humans, cells with 23 chromosomes) VI. New Frontiers 1
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a. PCR (polymer chase reaction) is a process which allows the rapid synthesis of large amounts of DNA from small samples 1) Useful in genetic typing for medical and criminal cases.
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