Lecture 7

Question 1

Model organisms are used to understand biological processes. What are typical unicellular model organisms for bacteria and yeast?

Answer 1

E. coli

S. cervisiae

Question 2

What is a protist?

Answer 2

not an animal, plant, or fungus

Question 3

Growing unicellular organisms can be done on minimal media and complete media. What are in both of these?

Answer 3

minimal media: carbon source (glucose), energy source (glucose), salts (Na+)

complete media: AAs, sugars, lipids, nucleotides, etc

Question 4

What is a genotype?

Answer 4

all genes and alleles present in a cell-organism

Question 5

What is a phenotype

Answer 5

the physical characteristics of a cell-organism

Question 6

What is a strain?

Answer 6

cells/organisms within a species that have a unique genotype and phenotype

Question 7

What is the source, genotype, and phenotype of prototrophic strains?

Answer 7

source: the wild

genotype: all genes are wild type (functional)

phenotype: can grow on CM and MM

Question 8

What is the source, genotype, and phenotype of auxotrophic strains?

Answer 8

source: a lab

genotype: one gene is mutant (non-functional)

phenotype: can only grow on CM

Question 9

What was the Srb and Horowitz experiment?

Answer 9

experimental proof of the one gene one enzyme hypothesis and invention of biochemical pathway analysis

1) exposed WT cells to UV radiation (1 mutation per cell)

2) collected mutant strains

3) isolate mutant strains unable to make arginine

4) classified strains into three groups: ornithine, citrulline, arginine

conclusion: pathway is ornithine to citrulline to arginine

Question 10

What is the purpose of a biochemical pathway analysis?

Answer 10

To determine how a cell/organism synthesizes organic molecules

each mutant strain has a single mutation

principle: each gene makes one enzyme, each enzyme does one step in the pathway. Therefore, a mutation in one gene prevents production of one enzyme and blocks the pathway at one place

Question 11

If the nutrient has rescued the mutant, the nutrient is (after/before) the blocked step

Answer 11

after

Question 12

If the nutrient has not rescued the mutant, the nutrient is (after/before) the blocked step

Answer 12

before

Question 13

What is the purpose of a transformation rescue?

Answer 13

To determine if a new mutation is in a known gene

Question 14

What is transformation?

Answer 14

the uptake and use of DNA or RNA by a cell/organism

it is called transfection in animals