Microbial Genetics Review Flashcards

Flashcards for key concepts in microbial genetics covering definitions, functions, processes, and comparisons related to DNA and gene expression.

Gene

A fundamental unit of heredity, a segment of DNA (or RNA in some viruses) that contains the instructions for building a specific protein.

DNA Polymerase

An enzyme that adds nucleotides to the 3' end of a growing DNA strand.

RNA Polymerase

An enzyme that creates RNA molecules by using DNA as a template.

DNA Ligase

An enzyme that joins DNA fragments together by forming phosphodiester bonds.

Transposase

An enzyme that moves genetic elements called transposons within a genome.

DNA Gyrase/Topoisomerase

An enzyme that relaxes DNA supercoiling to allow for replication.

DNA Helicase

An enzyme that separates the double-stranded DNA molecule to create a replication fork.

Primase

An enzyme that synthesizes short RNA primers on the DNA template to initiate replication.

5' to 3' Direction

The direction in which a new DNA strand is made, meaning nucleotides are added to the 3' end.

Leading Strand

The DNA strand that is synthesized continuously in the 5' to 3' direction.

Lagging Strand

The DNA strand synthesized discontinuously in short fragments called Okazaki fragments, also in the 5' to 3' direction.

Okazaki Fragments

Short, newly synthesized DNA sequences formed on the lagging strand during DNA replication, which are later joined by DNA ligase.

Base Pairing Rules (DNA)

A always pairs with T, and C always pairs with G.

Base Pairing Rules (RNA)

Adenine (A) pairs with uracil (U), and guanine (G) pairs with cytosine (C).

Transcription

The process of copying a segment of DNA into RNA for gene expression.

Translation

The process in which proteins are produced using RNA molecules as templates.

Messenger RNA (mRNA)

The product made as a result of transcription.

Polypeptide Chain

The product made as a result of translation, which folds to form a protein.

tRNA

Transfer RNA that delivers specific amino acids to the ribosome for protein assembly.

rRNA

Ribosomal RNA that forms the structural and functional core of ribosomes.

snRNPs

Small nuclear ribonucleoproteins that primarily function as core components of the spliceosome.

Nucleotide Excision Repair (NER)

The process by which enzymes identify, remove, and replace damaged DNA segments due to UV radiation.

Inducible Enzyme

An enzyme produced only when its specific substrate is present.

Repressible Enzyme

An enzyme that is normally active but is inhibited by the presence of a specific product.

Operon

A unit of gene regulation that consists of a promoter, operator, and structural genes.

Mutation

A permanent change in an organism's genetic material (DNA or RNA).

Mutagen

An agent that causes mutations.

Spontaneous Mutation

A mutation that occurs naturally without external influence.

Synonymous Mutation

A change in the DNA sequence that does not alter the amino acid sequence of the resulting protein.

Nonsense Mutation

A change in the DNA sequence that results in a stop codon, prematurely terminating protein synthesis.

Missense Mutation

A change in the DNA sequence resulting in a different amino acid being coded for, potentially altering protein function.

Frameshift Mutation

An insertion or deletion of nucleotides in a DNA sequence that is not a multiple of three, causing a shift in the reading frame.

R+ Cell

A cell containing a plasmid carrying genes that confer resistance to antibiotics.

Genetic Code

Three-nucleotide sequences in mRNA that specify a particular amino acid or signal the start or stop of protein synthesis.

F+ Strain

A donor strain with an F plasmid containing genes for conjugation.

Hfr Strain

A strain with the F plasmid integrated into its chromosome, allowing transfer of chromosomal DNA.

Transposons

DNA sequences that can move from one location to another within a genome; discovered by Barbara McClintock.