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Genetics Review

Genetics Review. By: Sabrina Banfi , Sammi Chung and Jia Tan. General information. Genes are units of inheritance that code for traits such as eye color or hair color.

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Genetics Review

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  1. Genetics Review By: Sabrina Banfi, Sammi Chung and Jia Tan

  2. General information • Genes are units of inheritance that code for traits such as eye color or hair color. • Genes are located on chromosomes. Individuals have 46 chromosomes that come in 23 pairs. One copy of each chromosome pair comes from our mother and the other from our father. • Each gene is made up of DNA containing genetic information.

  3. Genetic terms

  4. Types of Mutations • Mutations are changes in genes or chromosomes. • Mutations may be spontaneous from random errors in DNA or induced by chemicals or radiation. • A gene mutation is a change in a gene by substitution of a base, or adding or deleting a base, so that the gene no longer produces the "normal" protein. • eg: Point mutations (silent,missense, nonsense), insertions, deletions • A chromosome mutation is a change in the chromosome by loss or duplication of part of a chromosome or inversion of a some of it, or even the presence or absence of an entire chromosome. • eg: translocation, duplication, inversion, deletion

  5. Somatic vs. Germline Mutations

  6. Mendel Genetics Part 2 (Sabrina)

  7. Monohybrid Crosses -Mendel started fertilizing several plants. Mendel did a monohybrid cross with contrasting traits to produce the F1 generation. -Mendel allowed them to self-pollinate again to produce F2. -When Mendel crossed the seeds, he found that recessive traits disappeared in F1. -But when he reproduced them again, he found that the recessive trait reappeared as a ¼ probability in F2.

  8. Terms to Know -Alleles are known to be the genes. -Homozygous has two alleles that are the same. -Heterozygous has two different alleles from parents with different characteristics that can be dominant or recessive. -Law of segregation was formed when any individual produces gametes receives only one copy. -Allele combinations can often be predicted by Punnett Squares.

  9. Di-hybrid Crosses - Mendel performed another experiment by performing a dihybrid cross with double heterozygotes which he let them all self-pollinate. - Four different phenotypes appeared in F2 generation. -The law of independent assortment says alleles of different genes assort independently of one another. -The genes can be linked with the same 2 phenotype or unlinked with 9 different ones.

  10. Dominance is not always the case -Organisms can have an intermediate dominance which is a blending of characteristics. -Organisms can also have codominance which allows them to make their own phenotypes.

  11. Pedigrees -Pedigrees can be used to show the inheritance of phenotypes including specific illnesses. -Sex linked inheritance is an inheritance of a gene that is carried on a sex chromosome. Dominant alleles have a ½ probability and recessive alleles have a ¼ probability. -Many phenotypes are mainly shown in males because only one copy is needed for a rare allele. XY not

  12. Incomplete Dominance There are two alleles, but neither alleles completely mask the other. Ex: When a red and white flower mate, the offsprings should be red, but instead there are pink flowers.

  13. Incomplete Dominance Question 1. In northeast Kansas there is a creature know as a wildcat. It comes in three colors, blue, red, and purple. This trait is controlled by a single locus gene with incomplete dominance. A homozygous (BB) individual is blue, a homozygous (bb) individual is red, and a heterozygous (Bb) individual is purple. What would be the genotypes and phenotypes of the offspring if a blue wildcat were crossed with a red one?

  14. Epistasis One gene suppresses the expression of the other gene Ex: Albinism The gene that cause albinism will mask the gene that controls color. Melanin is not produced.

  15. Pleiotropy One gene influences multiple phenotypic trait Ex: Phenylketonuria (PKU) PKU is a disease that cause intellectual disability and reduced pigment in hair and skin.

  16. Sex Linkage Question 1. In humans, hemophilia is a sex linked trait. Females can be normal, carriers, or have the disease. Males will either have the disease or not (but they won’t ever be carriers) Show the cross of a man who has hemophilia with a woman who is a carrier. What is the probability that their children will have the disease? __________

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