12521159
Description
Flashcards by J yadonknow, updated more than 1 year ago
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Created by J yadonknow
over 6 years ago
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| Question | Answer |
| What is an autosome? | A non-sex chromosome that appears in equal frequencies between sexes |
| What is autosomal dominant? | Affected individuals have at least 1 affected parent (unless mutation has appeared de novo) Trait usually doesn't skip generations. |
| What is autosomal recessive? | Infantile onset epilepsy (GM3 synthase) Cystic fibrosis Phenylketonuria Appears both sexes w/ = frequency Parents can be unaffected Parents often related, although this depends on allele F in the population trait frequently skips generations |
| X-linked recessive | Red-green colour blindnes Haemophilia Appears in men more frequently than women Parents can be unaffected Fathers don't transmit to sons trait often skips generations. |
| X-linked dominant | Familial vitamin-D-resistant rickets Appears in females more often than males at least 1 parent affeted (unless de novo) Fathers don't transmit the train to their sons, do pass it to daughters Trait doesn't skip generations. |
| What is incomplete dominance? | Heterozygote of 2 incompletely dominant alleles has an intermediate phenotype between the 2 homozygotes e.g. red+white=pink. |
| What is co-dominance? | Heterozygote between 2 co-dominant alleles has the some of the 2 phenotypes |
| What is overdominance or heterozygote advantage? | Fitness of heteroz > either homoz Sickle cell disease cystic fibrosis A disease allele is present in the gene pool at higher f than would be expected given the nature of the disease |
| What is under-dominance or heterozygote disadvantage? | Homoz of either allele's fitness > heteroz Chromosomal rearrangements Significant implications for speciation because it typically causes the population to fix one of the two alleles This can reduce immigration potenetial and lead to populations becoming genetically isolated |
| What is an example of this? | Human chromosome 2 formed from a fusion of 2 ancestral chromosomes Should have been selected against in heterozygotes with the non-fused chromosomes Would have lead to gametes either missing or having extra chromosome arms, ergo missing/extra genes Fusion would only survive in very small populations here inbreeding and genetic drift is present. |
| How could this have arisen in the germ line? | Rearrangements in premiotic germ cells of an individual leading to more than one sibling offspring with the same rearrangement. If these siblings mate some of their progeny could be homozygous for the fusion chromosome only 2 generations after the genetic change |
| What is an allelic series? | Multiple alleles of an individual locus |
| What is a "wild type" allele? | An allele that is overwhelmingly common in a population |
| What are polymorphic alleles? | Loci controlling a highly variable train in a population e.g. hair colour |
| What does the ABO locus encode? | A glycosyltransferase |
| What is the most common O allele | Most common O allele has a 1bp deletion (relative to allele A) This results in a frameshift and so no active protein is produced. |
| What does allele A encode? | GST-A which adds alpha-N-acetylgalactosamine residue to the chain |
| What does allele B encode? | GST-B, which adds an alpha-galactose residue to the chain |
| How can a single allele be both dominant and recessive? | Can be dominant wrt to one trait and recessive to another In Drosophila many alleles that confer a dominant viable phenotype are also recessive elthal Similarly, in humans dominant viable alleles (e.g. skeletal defects) are not viable as homozygotes So if 2 D's are brought together, they compete like 2 charging bulls and their collision is lethal |
| What is pleiotropy? | When a single mutation can affect multiple processes Many gene products function in multiple contexts in the organism mutating the gene ill result in a variety of defects. e.g. protein phosphatase 1 |
| Gives us a rundown of PP1 | Catalytic SU binds to different targeting/regulatory SU Each cat/reg SU complex has a distinct target specificity Mutating catalytic SU creates a broad range of phenotypes, reflecting the function of this protein in many different biological contexts |
| Do a big fuck off thing showing dominance versus recessive | Sickle cell anaemia Homoz WT HbβA/HbβA Normal RBC Homoz defective HbβS/Hbβs Sickle cell anaemia Heteroz HbβA/Hbβs No disease |
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