WEEK 4: Mutation & Pathways (LAB)

Question 1

Biosynthetic Pathway

Answer 1

The synthesis process consists of a series of chemical reactions that sequentially convert precursors into more complex substances (intermediates) and finally into the organic compound (end product) required for growth.

This series of chemical reactions form a biosynthetic pathway. Each pathway has several steps, and each cell has many different pathways.

Question 2

One gene - One enzyme Hypothesis

Answer 2

Beadle and Tatum propose that genes function by encoding enzymes, and each gene codes a separate enzyme.

Question 3

Enzyme

Answer 3

Enzymes are proteins that help speed up metabolism or the chemical reactions in our bodies. They build some substances and break others down.

An enzyme catalyzes each step in the biochemical pathway, most enzymes are made of polypeptides, and each polypeptide is encoded by a gene (the one gene - one enzyme hypothesis).

Question 4

Polypeptide

Answer 4

A chain of amino acids linked by peptide bonds; is also called a protein.

Question 5

Gene

Answer 5

An inherited factor that helps determine a trait; is often defined at the molecular level as a DNA sequence that is transcribed into an RNA molecule.

Question 6

Complete Medium (CM)

Answer 6

A medium that contains all the substances required by bacteria for growth and reproduction. Auxotrophocmutants can grow on a complete medium.
- contains all organic and inorganic molecules required by an organism to grow

Question 7

Minimal Medium (MM)

Answer 7

A medium that contains the nutrients required by only phototrophic bacteria - typically a carbon source, essential elements such as nitrogen and phosphorous, certain vitamins, and other required ions and nutrients.
- only contains a carbon source, an energy source, and salts
- ex: glucose and unfiltered tap water
- organisms growing in this media must synthesize all complex organic compounds they need using many different biosynthetic pathways

Question 8

Wild-type

Answer 8

The trait or allele that is most commonly found in natural (wild) populations.

Question 9

Prototrophic

Answer 9

(Original feeders) they can grow in Minimal medium (MM)

Capable of using a carbon source, essential elements such as nitrogen and phosphorous, certain vitamins, and other required ions and nutrients to synthesize all the compounds needed for growth and reproduction, a phototrophic bacterium can grow on a minimal medium.
- Prototrophic cells can grow on MM and CM

Question 10

Allele

Answer 10

One of two or more alternative forms of a gene.

Question 11

Auxotrophic

Answer 11

Processing a nutritional mutation that disrupts the ability to synthesize an essential biological molecule; an auxotrophic bacterium cannot grow on a minimal medium but can grow on a minimal medium to which has been added the biological molecule that it cannot synthesize.

Question 12

Biomedical Pathway Analysis

Answer 12

An experiment used to identify blocked steps in a biosynthesis pathway is called a biochemical pathway analysis.
- This type of experiment involves growing an unknown auxotrophic strain on MM supplemented with the various organic molecules that occur within the biochemical pathway in question.

Question 13

Transformation

Question 14

A complication to the “One gene - One enzyme Hypothesis.”

Answer 14

Some enzymes consist of two different polypeptides where different genes encode each polypeptide. These are called heterodimers and are a complication to Beadel and Tatum’s one gene-one enzyme hypothesis because more than one gene is required to make these enzymes.
- still true tho that a single gene encodes a single polypeptide

Question 15

Model Genetic Organisim

Answer 15

An organism that is widely used in genetic research because it has characteristics, such as shot generation time and large numbers of progeny, that make it particularly useful for genetic analysis.

Question 16

Defined Medium

Answer 16

Every chemical and its amounts are known.

Question 17

Complex medium

Answer 17

Undefined because it contains components that cannot be precisely measured.

Question 18

Mutated cells

Answer 18

If a mutation occurs in a cell, that cell and all resulting offspring will have a non-functioning version of the gene in which the mutation occurred. We call this mutated version of the gene a mutant allele, where allele refers to different forms of a gene.
- can’t make a protein therefore the biosynthetic pathway is blocked therefore o minimal media, the cell cannot grow

Question 19

Auxotrophs

Answer 19

Microorganisms carrying a mutation that has a blocked biosynthetic pathway in effect are known as auxotrophs (nutritional mutants)
- auxotrophs can grow on CM because whichever organic molecule they are unable to produce would be present n the CM and thus be imported to the cell for survival

Question 20

Transformation Rescue Experiment

Answer 20

The process of taking in foreign DNA (transformation) that contains the normal version of the gene and thereby rescuing the auxotrophic strain is called transformation rescue.