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