dominance neither trait is dominant; in a hybrid condition, there is a blending in the phenotype.

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1 Genetics NAME Period Date <Notes #2- Heredity and Genetics> dominance neither trait is dominant; in a hybrid condition, there is a blending in the phenotype. - a condition when both alleles show up in the offspring (ex- AB blood type). Cross a pure red four o clock flower to a pure white four o clock flower. Four o clock flowers show incomplete dominance. Cross the offspring of the flowers above:

2 - more than two alleles that control a trait. blood type In humans, is a trait that has alleles. What is the genotype(s) of the following phenotypes? Human Blood Types A B AB O MULTIPLE GENES- - occurs when a group of gene act together to produce a single trait. Ex- height, weight, body build, eye shape, lips, and ears Also- color is controlled by 3 to 6 pairs of genes!! Even more gene pairs may control the color of your and. Polygenic inheritance is also seen in color of wheat, egg pairs grain production in cows, and in production in chickens. milk **********Traits with a LOT of variety are probably polygenic traits************ Human Genetics- Two human genetic disorders that result from gene mutations are: Sickle Cell Anemia - a homozygous recessive disorder where the red blood cells are sickle-shaped and do not carry enough oxygen to the cells. Cystic fibrosis - a homozygous recessive disorder where thick mucus is produced in the lungs (restricting oxygen intake) and the digestive system (limiting the breakdown and absorption of food.)

3 Sex Determination- The and chromosomes contain genes that determine sex (gender.) Males have. Females have. When males produce sperm, the sperm can have either an or a chromosome. When females produce eggs, the egg can only have an chromosome. What is the chance Mrs. Smith will have a girl? (She already has two boys!!) trait- a trait where the gene (allele) is located on the sex (X or Y) chromosome. Two examples of sex-linked traits that are carried on the X chromosome are: Color blindness Hemophilia - people cannot see shades of red and green. - a disorder where the blood does not clot properly. A man with colorblindness is married to a woman who has normal vision.

4 - a person who has an allele for a trait but who does not show the trait (phenotype) because they also have a normal allele. - a tool for tracing the occurrence of a trait in a family. Males are represented by squares and females are circles. If the shape is filled in they have the trait, if it is half filled in they are a carrier. Fill in the following pedigree chart from the sex-linked Punnett Square on the preceding page. - a process in which scientists go into change correct cells and or specific damaged or mutated genes. Genetic engineering has been used to put human genes into bacteria to produce INSULIN for diabetics!! - a chromosome map. The Human Genome Project has completed its goal of mapping the genes on the human chromosomes. It is now estimated that there are about genes on the human chromosomes. Some studies say there are 30,000-40,000 genes! (There is a difference in what markers are used to count the genes.) There are over base pairs in the human genome!! Why would we want to know our own genome? Possible advantages- identify certain disorders and then take steps to avoid the development of the disorder Possible disadvantages- could some employers could refuse to hire someone because of their traits, could they have higher insurance rates?

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