Genetics Lab Midterm Study Guide PDF

S. Cerevisiae also known as yeast, has two factors of respiration. o The first is Aerobic respiration which is when sugar is converted to carbon dioxide. o The second is Anaerobic respiration which is when sugar is converted to ethanol. In the yeast life cycle, reproduction can occur throug...

S. Cerevisiae also known as yeast, has two factors of respiration. o The first is Aerobic respiration which is when sugar is converted to carbon dioxide. o The second is Anaerobic respiration which is when sugar is converted to ethanol. In the yeast life cycle, reproduction can occur through vegetative reproduction and sexual reproduction. Reproduction through vegetative involves either a haploid to haploid or diploid to diploid. Cell division happens by budding (Mitosis). Sexual reproduction involves mating between two haploid cells; one being mating type A and the other being mating type a/alpha. The cells respond through pheromone which is produced by the opposite mating type. The cells will stop dividing and change their shape to form “shmoos” which leads to cell fusion and the formation of the zygote which will be diploid. - In sexual reproduction, the cells can undergo sporulation. Sporulation occurs during starvation or a nutrient deficient environment. The diploid cells will change from miotic grown to meiosis. Undergoing meiosis results in conversion from diploid to haploid cells (stress resistant ascospores). - In sexual reproduction, cells may also undergo germination which is opposite to sporulation. Germination occurs in a nutrient rich environment and the ascospores begin to divide mitotically and grow in a stable haploid phase. Germination will produce four Haploid (1N) segregants of meiosis. Basic Genetic Concepts Gene is the unit of genetic information encoded in DNA or RNA in case of some virus that specifies the composition of a protein and or functional RNA molecule Genotype is the information coded in the total DNA of an organism or also known as the genetic makeup Phenotype is the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment Allele is one of two or more alternative forms of a gene that usually arises through mutation and is responsible for phenotypic variation Wild type is the phenotype that is most observed in natural populations. The wild type is arbitrarily chosen as the benchmark stain. Controlled experiment is conducted when one variable is changed at a time to help identify the change in the outcome Dominant allele is the allele that expresses phenotypic effect even when heterozygous. Wild type is often more dominant over the mutant. Recessive allele is an allele that only expresses a phenotypic effect when homozygous (both alleles are recessive). In a heterozygote, dominant allele usually takes power over recessive allele. Epistasis is the interaction of separate non allelic genes, such that one gene will influences or interfere with the expression of another gene.  Genetic complementation is when an organism with a mutation produces the mutant phenotype will end up producing offspring with the wild-type phenotype when mated or crossed with an organism with a functional copy of that gene. - This is because the other strains genome supplies the wild type allele to “complement” the mutated allele if the stains genome) Auxotroph is a mutant stain that requires the addition of a nutrient to the media for growth. Prototrophic is a wild type stain that is able to produce nutrient without supplementation. Biosynthesis of Adenine The main difference between a wild type and mutant allele is that the wild type is functional, and the mutant is non-functional. The alleles of ADE2 would be ADE2(wildtype) /ade2(mutant) The alleles of ADE1 is ADE1(wildtype)/ade1(mutant) ADE1, ADE2 genotype would result in a white phenotype. ADE1, ade2 genotype would result in a red phenotype Ade1, ADE2 genotype would result in a pink phenotype Ade1, ade2 genotype would result in a red phenotype Nomenclature of yeast strains In HA1, the mating type is A, it is missing ADE1, has ADE2. The representation of HA1 would be ade1/ADE2 In HB1, mating type is a(alpha), representation of ade1/ADE2. In HA2, mating type is A, missing ADE2, which results in ADE1/ade2 In HB2, mating type a (alpha), representing ADE1/ade2 H will represent Haploid, A/B represents mating type A/a, and the number at the end which is 1 or 2 represents the mutation. 1 represents missing ADE1; instead has ade1. 2 represents missing ADE2 and has ade2 Growth and color from crosses HA1xHB2 will lead to white color HA1xHB1 will lead to pink color UV Radiation and Mutations The three UV types are UV-C, UV-B, UV-A UV-C is most damaging and filtered out by ozone stratosphere Normal cells repair most of the damage done by UV-B and UV-A radiations that penetrate into atmosphere Resistance to UV-A and UV-B UV radiations cause pyrimidine dimer mutation which prevents normal DNA replication. UV radiations are selectively absorbed by aromatic rings of the purine or pyrimidine bases  Ionizing radiations cause double strand and single strand breaks. They also indiscriminate which molecule they damage