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BIO 311 Midterm
| Question | Answer |
|---|---|
| what is a gene? | a hereditary unit of info |
| what is a gene locus? | the position of a gene on the chromosome |
| what is an alele? | one of 2 (or more) version of a gene that differs in the sequence and exisst at the same loci |
| what is a wild type phenotype? | the most prevalent phenotype in a population under natural conditons. |
| what is a mutant phenotype? | a deviation to the wild-type as a result from an allelic change in DNA seqeunce. |
| what is a loss of function mutation? | significant decrease or complete loss of functional gene product |
| what is a gain of function mutation? | gene product acquires a new function or expression increased above wild-type activity. |
| what is incomplete dominance? | heterozygous individuals display intermediate phenotypes between either homozygous type |
| what is codominance? | there is detectable expression of both alleles in heterozygotes |
| what does Upper case denote in nomenclature? | the dominant allele |
| what does lower case denote in nomenclature? | the recessive allele |
| what is the allele symbol named after? | the recessive allele |
| what are the phenotypes of pure breeding self crosses? | offspring will always have parental phenotype |
| what is the expected ratio of a monohybrid cross? | 3:1 |
| what is Mendel's first law? | the law of equal segregation- half of the gametes carry one member of gene pair, other half carry other member. |
| what is a test cross? what is it used for? | crossing an individual against a homozygous recessive tester. it is used to determine the genotype of an individual that is expressing the dominant phenotype |
| what are non-autosomes? | sex chromosomes |
| what does homogametic mean? | matching pair of sex chromosomes (exXX) |
| what does heterogametic mean? | no matching sex chromosomes (ex.XY) |
| what os a propositus? | the first member of a family who comes to the attention of a geneticist (usually has a disease) |
| what are the characteristics of an Autosomal Recessive Pedigree? | 1.disease often shows up from unaffected carrier parents 2.if both parents have the trait all of their children will have it 3.Males and Females have an equal likelyhood of being affected |
| what are the characteristics of an Autosomal Dominant Pedigree? | 1.No skipping generations, each affected indiviudal will have atleast one affected parent 2.Males and Females can transmit equally 3. 2 affected parents can produce unaffected children, but 2 unaffected parents can never have affected children |
| what is the difference between rare disease and polymorphism? | polymorphisms carries are common in population, rare disease carriers are not common |
| what are the characteristics of X-linked Recessive rare diseases? | 1.males affected more than females 2.if father is affected, none of the offspring will be if mom is not a carrier 3.all male offspring from an affected mom will be affected |
| what are the characteristics of X-linked Dominant rare diseases? | 1.all daughters of an affected male will be affected 2. no sons of an affected male will be affected unless mom is a carrier 3.an affected heteroxygous female will transmit affected allele to male and female offspring equally |
| what are the genotype probabilities of an A/A x a/a cross? | 100% A/a, all A phneotype |
| what are the genotype probabilities of an A/A x A/a cross? | 1:1 ratio of A/A and A/a 1:1 ratio of A to a phenotypes |
| what are the genotype probabilities of an A/a x a/a cross? | 1:1 ratio A/a and a/a 1:1 ratio of A and a phenotypes |
| what are the genotype probabilities of an A/a x A/a cross? | 1:2:1 ratio of A/A : A/a : a/a 3:1 ratio of A to a phenotypes |
| What is a dihybrid cross? | crossing 2 individuals that are true breeding for 2 traits |
| in what phase of mieosis do homologous pairs line up on the metaphase plate? | Metaphase 1 |
| how do you calculate degrees of freedom? | total number of variables - 1 |
| for what p values do we accept the null hypothesis? | values less than the p value for 0.05 |
| for what p values do we reject the null hypothesis? | values greater than the p value for 0.05 |
| what are lethal alleles? | when 2 copies of the mutant allele cause lethality (death) |
| what is penetrance? | the % of individuals with a mutation that show the phenotype |
| what is expressivity? | differing levels that a phenotype is expressed |
| what factors affect individals with the same mutation showing not exactly the same phenotype? | 1.environment 2.other genes --> genetic background 3. subtlety of mutant phenotype |
| what did Beadle and Tatum investigate? | the genetic control of cellular chemistry Neurospora took pure samples and zapped them to induce mutations, isolated mutated spores to become new strains to test which amino acid each mutation was lacking |
| what did Beadle and Tatum find? | numerous mutant strains were arginine auxotrophs, each muatation behanved as a single gene, mapped the mutations relative to other genes. |
| what are the steps to determining functional relationships between genes? | 1.mutate a population to generate mutations in genes 2.perform comlementation tests to determine the # of genes mutated 3.make double mutant line to determine gene interactions |
| what does it mean if genes compliemnt? | they are alleles of different genes |
| what does it mean if genes fail to compliment? | they are alleles of the same gene |
| what is epistasis? | when the phenotypes of a mutant allele masks the phenotype of the mutant allele of another gene |
| reccessive epistasis | the allele that masks another is recessive |
| dominant epistasis | the allele that masks another is dominant |
| what are suppressor mutation? | they reverse the effect of mutation in another gene --> results in wildtype |
| what are synthetic mutations? | mutations in 2 different genes individually do not cause a phenotype but together they do |
| what are linked genes? | two different genes that DO NOT sort independently, relativley close to one another on the same chromosome |
| what did Thomas Hunt Morgan study? | perfromed experiments with fruit flies to obsever patterns of inheritance. 2 autosomal genes : purple and vestigial |
| what did Morgan observe? | when 2 true breeding parents were crossed he did not see the expected 1:1:1:1 ratio. most offspring had the same phenotypes as the apretns. |
| what was the conclusion of Morgan's experiment? | the results did not follow Mendel's law of independent assortment. he suggested that linked genes do not assort independently, and most will reflect the parental phenotypes |
| what does syntenic mean? | genes are on the same chromosome |
| what is cis conformation? | wild type alleles are on the same homolog |
| what is trans confromation? | wild type alleles are on oppostie homologs |
| what are chiasmata? | cross-shaped structures that form during meisosi when dyads form a tetrad, evidence that crossover occurs |
| True or False? The frequency of recombination is directly related to the distance between genes? | TRUE |
| are genes that are closer together or farther apart more likely to cross over? | Farther apart |
| can two genes on the same chromosome assort independently? | yes, if they are 50+ map units apart they will appear unlinked |
| what is the expected phenotype ratio in a monohybrid cross? | 1:1 |
| what is the expected phenotype ratio in a monohybrid self cross? | 3:1 |
| what is the expected phenotye ratio in a dihybrid testcross with independent assortment? | 1:1:1:1 |
| what is the expected phenotype ratio of a dihybrid selfcross with independent assortment? | 9:3:3:1 |
Created by:
taylorplante