BIo 1AL- lab 7 (fruit fly genetics, comp. 2, PCR analysis)

(vibrio analysis) how do you remove primers, nucleotides, buffer, and taq polymerase from a PCR sample

spin column with silica membrane

• DNA binds tightly to silica membrane in the presence of salt

• contaminants are washed away using a salt buffer with ethanol

• elution: DNA is released from membrane using low salt buffer

(vibrio analysis) describe principles of agarose gel electrophoresis, and how PCR length affects mobility

• insert DNA into cathode (negatively charged) and it travels towards anode (pos charge)

• DNA sorts into longest —> shortest 

(yeast comp. 2) explain wether His- (histidine synthesis mutants) yeast cells would grow on YPD or SD plates

• YPD allows all mutant strains  to grow

• SD (synthetic defined) medium  lacks histidine, so strains will not grow unless they complement (they have mutations on different genes)

• sterile velvet is used to transfer from YPD to SD plate

define allele, gene, phenotype, genotype, heterozygote, homozygote, hemizygote, recombinant, homologs, independant assortment, recessive, dominant, incomplete dominance

• hemizygous is only one copy of a gene present (AY)

• homologs- two things that share a common ancestor

• true breeding- offspring that have the same traits as their parents

how to determine probabilities of different phenotypes and genotypes in F1 and F2 generations (autosomal AND sex linked)

• what alleles are dominant/recessive?

• do genes behave as if they are on autosomes or sex chromosomes

• do the genes assort independently or are they genetically linked

• if genetically linked, how far away are they from eachother

how to draw a genetic map using frequency of recombinants in progeny of a known cross

.When the frequency of recombinant progeny reaches 50%, the genes are considered genetically unlinked: they are either very far apart on the same chromosome or on different chromosomes.

If the frequency of recombinants is less than 50%, we can use this frequency to determine the genetic distance between the two genes.

chi square test

• make contingency table and total rows/columns

• make null hypothesis that there is no association

• expected frequencies: calculate (row total x column total)/grand total

• for each cell: (Observed-expected)²/expected

• add the results from each cell to get the final X² statistic

• use DF (rows-1) x (columns-1) and alpha (0.05) to determine what your X² value should be greater than to REJECT null hypothesis (significant) 

genetic notation

• The wild-type allele is indicated by the gene name, white or w, followed by the superscript ⁺, e.g., w⁺.

• the double lines represent the two chromosomes in a homologous pair

• if 2 different traits are genetically linked, the alleles are written on the same side of the same double lines

hypotheses concerning gene distribution

• genes are NOT linked, found on AUTOSOMES

• ONE gene is on an autosome the other is on a sex chromosome

• genes are genetically linked on either AUTOSOME OR one of the sex chromosomes

  • what is their map distance if they are linked?

parental vs recombinant gametes

map distance

probability that crossing over will occur between two genes

• if it’s less than 50%, the genes are linked by that percentage of map units

determining fly sex

Females are slightly larger and have a larger, lighter-colored abdomen that appears banded. The males have smaller, slightly darker abdomens, especially posteriorly. Males also have a tuft of thick, dark bristles (the sex comb) on each first leg.