genotypephenotypehomework

Chapter 20 Patterns Of Genetic Inheritance 1. Define genotype-refers to the genes of the individual. Alternative forms of a gene having the same position (locus) on a pair of chromosomes and affecting the same trait are called alleles. Alleles-alternative forms of a gene having the same position on a pair of chromosomes and affecting the same trait are called alleles. dominant allele- it is common to designate an allele by a letter, which represents the specific trait it controls, a dominant allele receives an uppercase letter. recessive allele- this is given the same letter but in lowercase homozgous dominant- consequently the zygote and subsequent individual have the alleles EE, which may be called a homozygous dominant gentype. homzygous recessive- in the second fertilization, the zygote has recieved two recessive alleles, ee, and the genotype is called homozygous recessive. Heterozygous- in the third fertilization the resulting individual has the alleles Ed which is called heterozygous genotype. Phenotype- the physical appearance of the individual in this case, unattached earlobes is called the phenotype. 2. What is the difference between genotype and phenotype? A phenotype can be anything from color blindness to a metabolic disorder, the genotype is just the letters.

3. What are the three possible genotypes and the two possible phenotypes for a characteristic that is controlled by two alleles, one being dominant and the other recessive? The genotype is the letters the two phenotypes are attached earlobe and unattached earlobe. The three genotypes are EE, Ee, and ee. The 4. Write down the question and answer for questions 1,2,3 on page 423. 1a. WW 1b. WS Ws WW Ss 1c. Tt tT 1d. Tt tg Tg gg 1e. Aa Bb AB ab 2a. Genotype 2b. Gamete 2c. Gamete 2d.genotype 3a.EeSs 3b.eeSS 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- this is a well known autosomal recessive disorder that occurs usually among Jewish people in the united states, most of whom are of central and eastern European descent.

Cystic fibrosis-is an autosomal recessive disorder that occurs among all ethnic groups, but it is the most common lethal genetic disorder among Caucasians in the united states.

Phenylketonuria- is an autosomal recessive metabolic disorder that affects nervous system development. Affected individuals lack an enzyme that is needed for the normal metabolism.

Sickle-cell disease- its an autosomal recessive disorder in which the re blood cells are not biconcave disks like normal red blood cells; they are irregular. In fact, many sickle-shaped. The defects is caused by an abnormal hemoglobin.

marfan Syndrome- an autosomal dominant disorder, is caused by a defect in the elastic connective tissue protein called fibrillin.

huntintongons's disease- is a neurological disorder that leads to progressive degeneration of brain cells. The disease is caused by a mutated copy of the gene for protein, called Huntington.