Genetics EOI Review for Biology Day 5 Lookabaugh

Genetics Alleles – different forms of the same gene Example: If the gene for tongue rolling is represented by the letter B B – can roll tongue b – cannot roll tongue If you have BB or Bb? What if you have bb? b b

Traits Dominant Trait Written as a capital letter to show that it is overpowering Recessive Trait Written as a lowercase letter to show that it can be covered up

Genotype The actual allele combination Example: AA, Aa, or aa Phenotype The physical appearance which expresses the genetic trait. Example: Widows peak, no widows peak

Homozygous When the two alleles are the same BB or bb Heterozygous When the two alleles are different Bb

Punnett Squares Predict possible genotypes of offspring A= red color a= blue color AA x aa 100% of offspring will have a genotype of Aa which will express as a red phenotype

Karyotypes - pictures of Chromosomes paired up Show the genes of an individual. Able to identify genetic disorders Trisomy – 3 chromosomes instead of 2 Klinefelter’s syndrome – XYY Separation of Chromosomes is Not right during metaphase of Meiosis when making gametes (NONDISJUNCTION)

Rules to read a pedigree 1.If most of the males in the pedigree are affected, then the disorder is usually X-linked. 2.If it is a 50/50 ratio between men and women the disorder is typically autosomal. 3.If the disorder is dominant, one of the parents must have the disorder. 4.If the disorder is recessive, neither parent has to have the disorder because they can be heterozygous.

Pedigree Tool to look at the passing of certain genetic traits on to offspring based of generations How it this TRAIT passed? Autosomal dominant

How is this trait passed? Autosomal recessive

DNA fingerprint Electrophoresis technique used to identify a person’s individual DNA used in paternity testing and criminal investigation

DNA fingerprint Can also be used to determine how closely related two organisms are

Determining Pedigree type Autosomal- Traits on passed on somatic cell Sex-linked- trait is passed on the X chromosome

Incomplete Dominance One trait is expressed/the other is not showing anything Phenotype shown is a weakened version of one allele expressing it’s protein Red x White = Pink

Co-dominance Both traits are expressed by making proteins Both phenotypes are expressed Red x Blue = Red & Blue

A,B, O Blood types MULTIPLE ALLELES- more than one type of allele for a gene. Type A= I A I A or I A i Type B = I B I B or I b i Type AB = = I A I B Type O= ii A and B are dominant O blood type is recessive

17 1 ABCDABCD

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20 4. In a certain group of lab mice black fur is dominant and brown fur is recessive. If two heterozygous mice mate and produce 16 offspring, how many of the offspring will probably have brown fur? A.0 B.4 C.8 D.12

21 5. Robert is conducting breeding experiments with mice. He crossed two brown mice and found that 25% of their offspring were white. Which conclusion from this experiment is most logical? A.White color is dominant over brown color B.One of the parent mice is homozygous for the dominant allele C.All of the offspring carry two copies of the recessive allele D.The white offspring are homozygous for the recessive allele

22 6. This diagram shows a pedigree for a recessive genetic disorder.

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8. In a species of fly, the allele for red eyes (R) is dominant to the allele for brown eyes (r). Red eye color in the flies is not sex-linked. Students crossed male and female flies that had red eyes and recorded the eye color of their offspring. Their data are shown below. Using the data in the table, what is the approximate ratio of red-eyed offspring to brown-eyed offspring? A.1:1 B.2:1 C.3:1 D.4:1

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A.HH B.Hh C.Hh D.Cannot be determined 11

1212 A.25% B.50% C.75% D.100%

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