Genetics

1. Define genotype - refers to the genes of an individual alleles - alterante forms of gene have te same position on a pair of chromosomes and affecting the same trait dominant allele -assigned an uppercase letter recessive allele - assigned a lower case letter homozgous dominant - an zygote with two dominant alleles homzygous recessive - the zygote has two recessive alleles heterozygous - a zygote with a dominant and recessive allele phenotype - a physical trait that is easily observable 2. What is the difference between genotype and phenotype? genotype is is the genes and phenotype is what the person looks like as a result of what their genotype is 3. What are the three possible genotypes and the two possible phenoyptes for a characteristic that is controlled by two alleles, one being dominant and the other recessive? Ww - widows peak Ee - unattached earlobes Ss - short fingers 4. Write down the question and answer for questions 1,2,3 on page 423. 1 - For each of the following genotypes give all possible gametes a - W b - WW, Ws, Ss, C tT D Tt, gg, Tg, tg E Aa, Ab, aB, ab, AB 2 - For each of the following state weather a genotype or a gamete is represented a - gamete b - genotype c - genotype d - genotype 5. Define the following genetic disorders on pp. 431 to 432 Make sure you describe the function of the gene that is mutated and what happens with the mutated gene. Tay-sachs disease - a lack of the enzzyme hexosaminidase devolopment in a baby starts to slow down and neurological impairment become apparent cystic fibrosis - Chloride ions fail to pass through a plasma membrane channel thick mucus interferes with the function of the lungs and pancreas the lugs become infected frequently phenylketonuria - individuals lack an enzyme that is needed for the normal metabolism of he amino acid phenylalanine severe mental retardation results sickle-cell disease - the red blood cells are not biconcave disks like normal red blood cell. Cells cant pass along narrow capillary passageways as disk shaped cells can. anemia and low resistance to infection marfan Syndrome - defect in connective tissue protein called fibrillin result in long limbs and acaved in chest the aorta wall is weak huntintongons's disease - caused by a mutated copy of the gene for a protein called huntingtin neurological disorder that leads to progressive degeneration of brain cells