Ch. 9 & 10 Microbial Genetics and Genetic Engineering

UNIT 2 EXAM

Genetics

The study of heredity and how traits are passed from one generation to the next.

Genome

Total DNA content in an organism.

Gene

A segment of DNA that codes for a protein or functional RNA.

Genotype vs. Phenotype

Genotype = Genetic makeup 

Phenotype = Observable traits expressed by those genes.

Genomics

The study of an organism’s entire genome and how genes interact.

DNA replication

The process of making an identical copy of DNA before cell division.

What does it mean that replication is semiconservative?

Each new DNA molecule has one old (template) strand and one new strand.

What are okazaki fragments

Short DNA segments are synthesized on the lagging strand.

Transcription

Process of copying DNA into mRNA.

Enzyme responsible for transcription

RNA polymerase

Translation

Process of reading mRNA to build a polypeptide (protein).

What organelle carries out translation?

Ribosomes

Codons

Triplets of nucleotides on mRNA that code for specific amino acids.

Anticodons

Complementary triplets on tRNA that match mRNA codons.

What is the START codon

AUG

What are STOP codons

UAA, UAG, UGA -signal the end of translation

Operon

A group of genes controlled by a single promoter-common in prokaryotes.

Parts of the lac operon

Promoter (P)- RNA polymerase binding site.

Operator (O)- on/off switch controlled by repressor.

Structural genes (lacZ, lacY, lacA)- code for enzymes to metabolize lactose.

How does an operon work?

No lactose → repressor binds operator → genes off

Lactose present → lactose binds repressor → repressor releases → genes on.

Why is the operon model important?

It shows how bacteria regulate gene expression efficiently based on environmental needs.

Mutation

A change in the DNA sequence.

Main types of Mutation

Point, Missense, Nonsense, Silent, Frameshift mutation

What causes mutations?

Spontaneous: random DNA replication errors.

Induced: caused by mutagens (UV light, chemicals, radiation).

How can mutations be beneficial?

They can introduce genetic variation or antibiotic resistance.

Horizontal Gene Transfer

Movement of DNA between organisms (not parent to offspring).

Plasmid

A small circular DNA molecule independent of the chromosome; can carry antibiotic resistance genes.

R plasmids

Resistance plasmids that provoke resistance to multiple antibiotics.

Restriction Enzymes

Enzymes that cut DNA at specific sequences (use to make recombinant DNA).

Recombinant DNA Technology

Combining DNA from two different sources to form new genetic combinations.

PCR (Polymerase Chain Reaction)

A technique that amplifies (copies) specific DNA sequences using heat and enzymes.

What enzyme is key to PCR?

Taq polymerase (heat-stable DNA polymerase).

Gel Electrophoresis

Technique that separates DNA fragments by size using an electric current.

What is CRISPR-Cas9

A bacterial defense mechanism adapted for genome editing- uses a guide RNA to target specific DNA sequences and Cas9 to cut them.

Reverse Transcriptase

Enzyme that synthesizes DNA from RNA (used in retroviruses and cDNA synthesis)

How can mutants be detected in the lab?

By observing phenotype changes or using selection (antibiotic resistance).

Auxotrophs

Mutants that require additional nutrients that the wild type does not.

What are some uses of recombinant DNA technology?

Production of insulin, vaccines, and enzymes.

Gene therapy

Agriculture (GMOs)

Environmental cleanup (bioremediation)

What is DNA sequencing used for?

Determining the exact order of nucleotides in a DNA molecule.