Molecular Genetics and Biotechnology

Vocabulary practice flashcards covering nucleic acid structure, DNA replication enzymes and mechanisms, protein synthesis, gene regulation operons, and genetic engineering biotechnology.

Frederick Griffith

The scientist credited with discovering transformation by demonstrating that a chemical substance from heat-killed pathogenic bacteria can be taken up by living non-pathogenic bacteria, transferring genetic characteristics.

Avery, MacLeod, and McCarty

The scientists who determined that the transforming substance from dead bacteria is destroyed by DNAse, identifying DNA as the transforming genetic material.

Meselson and Stahl

The researchers who demonstrated that DNA replication is semiconservative by measuring DNA density gradients using heavy radioactive nitrogen-containing bases.

Watson and Crick

The scientists who discovered the double helix structure of DNA, featuring two antiparallel nucleotide chains running in opposite directions.

Erwin Chargaff

The biochemist who discovered that the ratio of adenine to thymine ($\text{A}:\text{T}$) and guanine to cytosine ($\text{G}:\text{C}$) in any given DNA molecule is always $1:1$.

Nucleotide

The monomer subunit of DNA and RNA, composed of three components: a five-carbon sugar (deoxyribose or ribose), a nitrogenous base, and a phosphate group.

Purine

A double-ring nitrogenous base class that includes adenine ($\text{A}$) and guanine ($\text{G}$).

Pyrimidine

A single-ring nitrogenous base class that includes cytosine ($\text{C}$), thymine ($\text{T}$), and uracil ($\text{U}$).

Phosphodiester Bond

The covalent bond that links adjacent nucleotides along the sugar-phosphate backbone of a DNA or RNA polynucleotide chain.

Antiparallel

The structural arrangement in double-stranded DNA where the two complementary strands run in opposite orientations, with one strand oriented $5' \rightarrow 3'$ and the other $3' \rightarrow 5'$.

Complementary Base Pairing

The principle where the nitrogen base sequence of one DNA chain dictates the sequence of the other through hydrogen bonding ($\text{A}$ pairs with $\text{T}$ or $\text{U}$; $\text{C}$ pairs with $\text{G}$).

Histone

A protein that eukaryotic DNA wraps around to organize, compact, and structure chromatin within the nucleus.

Euchromatin

Loosely packed chromatin structure that is transcriptionally active and accessible to RNA polymerase.

Heterochromatin

Tightly coiled, condensed chromatin structure containing transcriptionally inactive genes.

Telomere

A repetitive, non-coding nucleotide sequence located at the end of a eukaryotic chromosome that functions like an aglet to protect the chromosome from degradation.

Semiconservative Replication

The process of DNA synthesis in which each resulting double-stranded DNA molecule contains one conserved parental template strand and one newly synthesized strand.

Origin of Replication

The specific sequence or site where DNA replication begins, representing the peak or center of a replication bubble.

Replication Fork

The Y-shaped region of a replicating DNA molecule where helicase is actively unwinding and separating the double strands.

Replication Bubble

The opened, unwound area of active DNA replication containing replication forks moving in opposite directions.

Helicase

The enzyme responsible for unwinding and untwisting double-stranded DNA at the replication fork.

Topoisomerase

The enzyme that reduces supercoiling strain ahead of the advancing replication fork.

RNA Primase

The enzyme that synthesizes a short RNA primer complementary to the DNA template to initiate DNA replication.

DNA Polymerase III

The enzyme that adds complementary DNA nucleotides to the growing DNA daughter strand in the $5' \rightarrow 3'$ direction.

DNA Polymerase I

The enzyme that proofreads and edits DNA errors, removes RNA primers, and replaces them with DNA nucleotides.

DNA Ligase

The enzyme that joins DNA fragments (such as Okazaki fragments) by catalyzing the formation of phosphodiester bonds.

Leading Strand

The new DNA strand that is synthesized continuously toward the replication fork in the $5' \rightarrow 3'$ direction.

Lagging Strand

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

Okazaki Fragment

A short fragment of newly synthesized DNA produced discontinuously on the lagging strand during replication.

Transcription

The process of copying a DNA template sequence into a complementary messenger RNA ($\text{mRNA}$) molecule.

RNA Polymerase

The enzyme that binds to a promoter region and synthesizes RNA by adding complementary RNA nucleotides to a growing strand.

Promoter

A specific region of DNA sequence recognized and bound by RNA polymerase to initiate transcription.

Intron

A non-coding sequence of pre-$\text{mRNA}$ that is spliced out and removed during mature RNA processing.

Exon

A protein-coding nucleotide sequence that is kept in mature $\text{mRNA}$ after RNA splicing and subsequently translated.

Poly-A Tail and 5' Cap

Structures added to the ends of pre-$\text{mRNA}$ during processing to prevent hydrolytic enzymatic degradation in the cytoplasm.

Translation

The process occurring at the ribosome where the nucleotide sequence of $\text{mRNA}$ is converted into an amino acid sequence (polypeptide).

Codon

A sequence of three consecutive bases on $\text{mRNA}$ that codes for one specific amino acid or a termination signal.

Anticodon

A sequence of three nucleotides on a $\text{tRNA}$ molecule that base-pairs complementarily with a codon on $\text{mRNA}$.

A Site (Aminoacyl Site)

The site on the ribosome that receives an incoming $\text{tRNA}$ carrying an unattached single amino acid.

P Site (Peptidyl Site)

The site on the ribosome that holds the $\text{tRNA}$ covalently attached to the growing polypeptide chain.

Point Mutation

A type of genetic mutation that changes a single nucleotide in the DNA sequence, affecting only one codon.

Frameshift Mutation

A mutation caused by the insertion or deletion of nucleotides not in multiples of three, which shifts the reading frame of all subsequent codons.

Reverse Transcriptase

An enzyme that synthesizes complementary DNA ($\text{cDNA}$) using an RNA template.

Operon

A genetic regulatory system found in bacteria consisting of a cluster of related structural genes controlled together by a promoter and an operator.

Operator

A DNA segment near or within an operon's promoter that functions as the on/off switch by binding a regulatory repressor protein.

Repressor Protein

A regulatory protein that binds to the operator region to physically block RNA polymerase and turn an operon off.

Inducer

A specific molecule that binds to and inactivates a repressor protein, causing it to release from the operator and turning the operon on.

Corepressor

A molecule that interacts with an inactive repressor protein, altering its shape to allow it to bind to the operator and turn the operon off.

DNA Methylation

The addition of methyl ($-\text{CH}_3$) groups to DNA, which typically compacts chromatin and decreases transcription.

Gene Amplification

The cellular process of selectively making multiple copies of specific genes whose protein products are required in abundance.

Differential mRNA Processing

A regulatory mechanism in which pre-$\text{mRNA}$ exons and introns are alternatively spliced, allowing one gene to produce multiple protein variants.

Catabolite Activator Protein (CAP)

A bacterial regulatory activator protein that binds near the promoter to stimulate RNA polymerase binding and transcription when glucose is scarce.

Plasmid

A small, circular, self-replicating DNA molecule found in bacteria that is physically separated from chromosomal DNA.

Bacterial Transformation

The process by which bacterial cells take up foreign naked genetic material from their environment and express the newly acquired genes.

Restriction Enzyme

An enzyme that recognizes specific target nucleotide sequences and cuts double-stranded DNA into discrete fragments.

Sticky Ends

Short, single-stranded overhangs of DNA generated by staggered cuts from restriction endonucleases.

Recombinant DNA

A DNA molecule formed in the laboratory by combining genetic material originating from two different species or sources.

Polymerase Chain Reaction (PCR)

A biotechnology laboratory method used to rapidly copy and amplify specific DNA target molecules in vitro.

Gel Electrophoresis

A technique used to separate macromolecules, such as DNA fragments, based on their molecular size and electrical charge through a matrix.

Restriction Fragment Length Polymorphism (RFLP)

DNA fragments of varying lengths produced by restriction enzyme digestion that are used to analyze genetic differences and identity.

DNA Hybridization

The technique of mixing a radioactive or fluorescent labeled DNA probe of known sequence with unknown single-stranded DNA to detect complementary sequences.

cDNA (Complementary DNA)

A DNA molecule synthesized from a messenger RNA template using the enzyme reverse transcriptase.

Transgenic Organism

An organism that contains and expresses functional genes artificially introduced from a completely different species.

pGLO Plasmid

An engineered plasmid containing the bla gene for ampicillin resistance, the GFP gene for green fluorescence, and the araC regulatory gene.

Bacteriophage

A specialized virus that infects and replicates within bacterial cells.