Microbial Genetics and Genetic Engineering Vocabulary

Flashcards testing core vocabulary terms and definitions from lecture materials on Microbial Genetics and Genetic Engineering.

Genome

The sum total of genetic material in a cell, existing as DNA in cellular organisms and as DNA or RNA in viruses.

Chromosome

A cellular structure composed of DNA complexed with protein that constitutes the genetic material of an organism.

Plasmid

A small, circular, extrachromosomal DNA molecule found in bacteria and some fungi and protozoa that replicates independently of the chromosome.

Gene

The fundamental unit of heredity; a structural gene is a linear sequence of nucleotides that codes for a specific protein or functional RNA.

Genotype

The genetic makeup or unique arrangement of genes contained within an organism's genome.

Phenotype

The observable physical traits, structural characteristics, and metabolic activities expressed as a result of an organism's genotype.

Purine

A nitrogenous base containing a heterocyclic aromatic two-ring structure consisting of a pyrimidine ring fused to an imidazole ring; includes adenine and guanine.

Pyrimidine

A nitrogenous base containing a single six-membered heterocyclic aromatic ring with two nitrogen atoms at positions 1 and 3; includes cytosine, thymine, and uracil.

Antiparallel Arrangement

The structural orientation of double-stranded DNA where one strand runs in the $5'$ to $3'$ direction and the complementary strand runs in the $3'$ to $5'$ direction.

Semiconservative Replication

The mechanism of DNA duplication in which each newly formed double-stranded DNA molecule consists of one original parent template strand and one newly synthesized daughter strand.

Helicase

An enzyme involved in DNA replication that functions in unzipping the DNA double helix.

Primase

An enzyme involved in DNA replication that functions in synthesizing an RNA primer.

DNA Polymerase III

The primary enzyme complex in bacteria that adds bases to the new DNA chain during replication and proofreads the chain for mistakes.

DNA Polymerase I

An enzyme that removes RNA primers, closes gaps, and repairs mismatches during DNA replication.

Ligase

An enzyme responsible for the final binding of nicks in DNA during synthesis and repair.

Gyrase

A bacterial enzyme involved in DNA replication that functions in supercoiling DNA.

Leading Strand

The newly synthesized DNA strand that is created continuously in the $5'$ to $3'$ direction toward the replication fork.

Lagging Strand

The newly synthesized DNA strand that is produced discontinuously in short segments away from the replication fork.

Okazaki Fragment

A short segment of newly synthesized DNA produced on the lagging strand template during discontinuous DNA replication.

Transcription

The biological process in which a DNA template strand is used by RNA polymerase to synthesize a complementary RNA transcript.

Translation

The biological process in which genetic information encoded in an mRNA transcript is decoded at ribosomes to assemble amino acids into proteins.

Messenger RNA (mRNA)

A single-stranded RNA transcript that carries the DNA master code in nucleotide triplets (codons) to the ribosome to direct protein synthesis.

Transfer RNA (tRNA)

An RNA molecule with a cloverleaf secondary structure that brings specific amino acids to the ribosome during translation according to its anticodon sequence.

Ribosomal RNA (rRNA)

RNA that forms the major structural component of ribosomal subunits and participates directly in protein synthesis.

Codon

A sequence of three consecutive nucleotides on an mRNA strand that codes for a specific amino acid or signals translation stop or start.

Anticodon

A specific triplet of nucleotides located on a tRNA molecule that base-pairs complementarily with a corresponding mRNA codon.

Promoter Region

A specific DNA sequence upstream of a gene that is recognized and bound by RNA polymerase to initiate transcription.

Intron

A noncoding intervening sequence within eukaryotic genes that is transcribed into pre-mRNA but removed by splicing prior to translation.

Exon

A coding region of eukaryotic DNA that remains in the mature mRNA transcript after splicing and is translated into protein.

Operon

A collection of genes in bacteria that code for products with a coordinated function and are regulated under a single promoter/operator system.

Mutation

Any permanent, inheritable change in the nucleotide sequence of an organism's genetic information.

Wild Type

A natural, nonmutated characteristic or strain of a microorganism commonly found in nature.

Mutagen

Any physical or chemical agent that interacts with DNA in a disruptive manner to induce genetic mutations.

Missense Mutation

A substitution mutation that causes a different amino acid to be incorporated into a protein.

Nonsense Mutation

A substitution mutation that converts a normal codon into a stop codon, resulting in premature termination of protein synthesis.

Frameshift Mutation

A mutation caused by the insertion or deletion of nucleotides that alters the reading frame of mRNA, changing every amino acid after the mutation site.

Conjugation

A mode of bacterial gene transfer involving a donor cell with a pilus forming a direct bridge with a live recipient cell to transfer DNA.

Transformation

An indirect process of bacterial recombination where a competent recipient cell takes up free extracellular donor DNA from its environment.

Transduction

An indirect bacterial gene transfer mechanism in which a defective bacteriophage virus carries host DNA from a donor cell to a recipient cell.

Genetic Engineering

The direct, deliberate modification of an organism's genome in a laboratory environment.

Restriction Endonucleases

Bacterial enzymes that recognize specific palindromic DNA sequences and cleave DNA strands crosswise at those sites.

Gel Electrophoresis

A technique that uses an electric current to separate DNA fragments or other macromolecules through a gel matrix based on size and charge.

Polymerase Chain Reaction (PCR)

An in vitro technique used to rapidly amplify small segments of target DNA into millions of copies through repeated thermal cycles of denaturation, priming, and extension.

Recombinant DNA Technology

The process of combining DNA from different sources to create new genetic combinations that are inserted into host organisms.

Genetically Modified Organism (GMO)

An organism whose DNA has been altered at the genomic level using genetic engineering techniques.

Transgenic Organism

A specific type of GMO that contains genes or DNA sequences received from a completely different species.

Gene Therapy

A medical technique that replaces a faulty or missing gene with a normal functional gene to correct genetic defects and cure disease.

DNA Fingerprinting

A forensic and diagnostic tool that analyzes unique patterns of DNA fragments to identify individuals, hereditary relationships, or disease risks.

Reverse Transcriptase

An enzyme that synthesizes single-stranded complementary DNA (cDNA) using an RNA molecule as a template.

Complementary DNA (cDNA)

DNA synthesized in vitro from mature mRNA using reverse transcriptase and DNA polymerase, free of noncoding introns.