lecture 11- gene function and mutational analysis

Question 1

forward genetics

Answer 1

identification of mutants and description of their heritable phenotypes precedes molecular analysis of products (change away from wild-type allele)

Question 2

reverse genetics

Answer 2

based on genome sequences, gene of potential interest is mutated and the phenotype of mutated gene is studied (change back towards wild-type allele)

Question 3

morphological mutations

Answer 3

change in shape or form

Question 4

biochemical mutations

Answer 4

screening for auxotrophs from mutagenized phototrophs by supplying various substrates required for growth

Question 5

prototroph

Answer 5

an organism that can grow on minimal growth media

Question 6

auxotroph

Answer 6

a mutant strain that cannot synthesize molecules required for growth and needs a special substrate to grow

Question 7

lethal mutation

Answer 7

premature death, recessive lethals are more useful than dominant lethals that are difficult to maintain

Question 8

conditional mutations

Answer 8

display wild-type under permissive (non-restrictive) conditions, and display mutant phenotype under restrictive conditions

Question 9

george beadle and edward tatum

Answer 9

performed the first genetic dissection of a biochemical pathway- genes specify enzymes and catalyze specific steps leading to a product.

Question 10

complementation test

Answer 10

generate heterokaryon by fusing 2 mutants. if the heterokaryon does not grow on media without Met, then mutations are in the same gene (mutations are mutant alleles of the same gene)

Question 11

complementation test (other effect)

Answer 11

generate heterokaryon by fusing cells from 2 mutants. if heterokaryon does grow on media without Met, then mutations are in 2 different genes. there are 2 possible segregations (2 unlinked genes, and 2 linked genes)