Microbial Genetics Review

Comprehensive vocabulary flashcards covering microbial genetics, DNA structure, replication, gene expression (transcription and translation), operon regulation, and types of mutations.

Genetic

The study of genes, how they store information, how that information is expressed, and how it is replicated.

Gene

A region of DNA that codes for a functional product, usually a protein.

Chromosome

A structure made of DNA that stores genetic information.

Genome

All of the genetic information in a cell; in bacteria, this includes the chromosome and plasmids.

Codon

Three nucleotides on mRNA that code for one amino acid.

Reading frame

The way the ribosome reads mRNA (Ex. AUG GCU UAC…).

Anticodon

Three nucleotides on tRNA that pair with the codon.

Introns

DNA sequences that are removed and NOT translated; mostly found in eukaryotes.

Exons

DNA sequences that remain and ARE translated.

Sense codons

Codons that code for an amino acid.

Nonsense codons

STOP codons that end translation.

Covalent bonds

Strong bonds that hold a single strand of nucleotides together (the sugar-phosphate backbone).

Hydrogen bonds

Weaker bonds that form between specific base pairs to hold two DNA strands together.

Complementary base pairs

Cytosine and guanine form one pair; thymine and adenine form the other.

Semiconservative replication

DNA replication where existing parent strands are used to create new daughter strands.

Leading strand

The daughter strand that is copied continuously during DNA replication.

Lagging strand

The daughter strand made in a series of Okazaki fragments.

DNA polymerase

The enzyme responsible for reading DNA and building a new DNA strand.

RNA primase

The enzyme (also called primase) that makes a primer for DNA replication.

DNA ligase

The enzyme involved in joining DNA fragments.

DNA helicase

The enzyme involved in unwinding the DNA double helix.

Gene expression

The process through which cells make proteins, consisting of transcription and translation.

Transcription

The process of copying DNA into RNA.

RNA polymerase

The enzyme that reads DNA and builds an mRNA copy only during transcription.

Promoter

The START sign where RNA polymerase binds to begin transcription.

Operator

The control switch that can allow or block transcription; it is part of an operon.

Terminator

The STOP sign where RNA polymerase stops and mRNA is released.

Messenger RNA (mRNA)

RNA that carries the genetic message from DNA to the ribosome.

Transfer RNA (tRNA)

RNA that brings amino acids to the ribosome and matches an mRNA codon with its anticodon.

Ribosomal RNA (rRNA)

RNA that makes up the ribosome and helps build proteins.

Ribosome

The site of translation that reads mRNA, matches tRNA anticodons, and joins amino acids together.

Translation

The process of converting mRNA into a protein.

Redundancy

The feature of the genetic code where many different codons code for the same amino acid.

Operon

A group of genes controlled together under one promoter and operator; found only in prokaryotes.

Repressor

A protein that binds to the operator to stop transcription.

Lac operon

An inducible operon used to break down lactose; it turns ON when lactose is present and removes the repressor.

Trp operon

A repressible operon used to make tryptophan; it turns OFF when tryptophan is abundant by activating the repressor.

Mutation

A change in the DNA sequence.

Spontaneous mutation

A mutation that occurs naturally due to errors during DNA replication.

Mutagen

An outside agent, such as UV light, X-rays, or chemicals, that increases the rate of mutations.

Missense mutation

A mutation that changes one sense codon into a different sense codon, resulting in a different amino acid.

Nonsense mutation

A mutation that changes a sense codon into a nonsense (STOP) codon.

Silent mutation

A mutation that changes one codon into a different codon for the same amino acid, resulting in no change to the protein.