Exam 5 Study Guide--Chapters 10 and 14

Exam 5 Study Guide--Chapters 10 and 14 - EXAM 5 MATERIAL...

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EXAM 5 MATERIAL Chapter 10—Patterns of Inheritance The Physical Basis of Heritance Genes are sequences of nucleotides at specific locations on chromosomes. o Inheritance is the process by which the characteristics are passes on to offspring. o A gene is a unit of DNA that encodes information needed to produce proteins, cells, and entire organisms. Can be a few hundred to many thousands of nucleotides in length. o The location of a gene on a chromosome is called its locus (plural = loci). o Homologous chromosomes (homologues) carry the same kinds of genes for the same characteristics Genes for the same characteristics are found at the same loci on both homologous chromosomes. o Genes for a characteristic found on homologous chromosomes may not be identical. 1) Alternative versions of genes found at the same gene locus are called alleles. 2) Alleles are formed by mutations. If a mutation occurs in gametes , the cells that become sperm or eggs, then the mutation can be passes on from parent to offspring. 3) An organism’s two alleles may be the same or different. Each cell carries 2 alleles per characteristic, one on each of the 2 homologous chromosomes. If both homologous chromosomes carry the same allele (gene form) at a given gene locus, the organism is homozygous at that locus. If 2 homologous chromosomes carry different alleles at a given locus, the organism is heterozygous , also called hybrid . o Paring In the ordinary body cells (not sperm or eggs) of many organisms, the chromosomes occur in pairs. Each species has a characteristic number of chromosomes. Human cells contain 46 chromosomes, 23 pairs. 22 pairs of Autosomes (the non-sex chromosomes), and 1 pair of sex chromosomes. o The Punnett Square Method predicts offspring genotypes and phenotypes from combinations of parental gametes. Assign letters to the different alleles for the characteristic under consideration (uppercase for dominant, lowercase for recessive). Determine the possible gametes from both parents. Write the gametes from each parent, along each side of a 2 x 2 grid (Punnett Square). Fill in the genotypes of each pair of combined gametes in the grid.
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Determine the genotypic ratio based on the outcome of the Punnett Square. Based on which traits are dominant and which are recessive, calculate the predicted phenotypic ratio. How were the principles of inheritance discovered? o Gregor Mendel —Austrian monk in a monastery in the late 1800s. Discovered patterns of inheritance and many essential facts about genes, alleles, and the distribution of alleles in gametes during sexual reproduction. He chose edible pea plant for his experiments. Allowed him to see patterns in the way plant characteristics were inherited.
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This note was uploaded on 10/30/2011 for the course BIOLOGY 1001 taught by Professor Crousillac during the Summer '10 term at LSU.

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Exam 5 Study Guide--Chapters 10 and 14 - EXAM 5 MATERIAL...

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