Unit 2 Exam: How does inheritance work?

Conduct a monohybrid cross to determine probabilities of genotypic and phenotypic frequencies

(on study guide question #2)

Law of segregation

Mendel's law of inheritance the chromosome itself splits in half. alleles (one from each parent) get separated during gamete formation and get put into different gamete cells. This is why a recessive allele can appear in a later generation because the dominant will be separate from it

Law of independent assortment

Mendel's law of inheritance how mother's and father's genes get separated for one homologous pair has no bearing on the direction mother's or father's gene go for other pairs, it is totally random. The allele you get from your dads chromosome has no relation to the allele you get from your moms chromosome.

Chromosomes

a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carries genetic info in the form of genes. (pic on study guide question #2)

Contrast "blending" and Mendelian models of inheritance

child inherits a blend from both mother and father's genes, an intermediate appearance of offspring vs. for any given gene an allele is inherited in an all or nothing pattern, not a blend but instead they are inherited as distinct traits

Incomplete dominance

exception to Mendelian inheritance (blending) when the dominant trait is not entirely dominant over the recessive, neither allele is 100% dominant, so the phenotype is in fact a blend Ex. a teel person tan cow from brown parent and white parent

Codominance

exception to Mendelian inheritance more than 2 alleles are dominant together, both traits from the allele are both expressed equally (both are dominant) Ex: blood type spots on a cow

Polygenic inheritance

exception to Mendelian inheritance more than one gene, combo of multiple genes coding for one trait (different versions of eye color due to multiple traits) Ex. eye color controlled by at least 3 genes

Pleiotropy

exception to Mendelian inheritance one gene (allele) causing several different phenotypes Ex. marfan syndrome- unusually tall, thin, long limbs, near sighted, more likely to suffer from ruptured aorta (defective connective tissue cause by a single gene)

Epigenetic inheritance

exception to Mendelian inheritance the body decides which genes are expressed based on chemicals in your body, whether to be turned on or off, controlled by chemicals in your body (cellular memory) Ex. genetic inheritance of cancer can be prevented example, broccoli turns on anti cancer genes, so if you eat broccoli you will have a smaller chance of getting cancer. Ex. anti cancer genes or cancer genes can be turned on (when engaging in habits like smoking) and passed down

Locus

location on the chromosome (plural- loci)

Gamete

male or female germ cell that is able to unite with another of the opposite sex in sexual reproduction to form a zygote

Genetic inheritance

normal genes that are turned on and off

Homologous chromosomes

one from mom and one from dad, carry same genes at same loci, identical alleles on both chromatids (halves) from each parent