BIO1406 Unit 3 Exam Review: Chapters 14, 15, 16 & 17

Vocabulary flashcards covering key molecular biology terms, mechanisms, operons, and biotechnologies for BIO1406 Unit 3 Exam Review (OpenStax Chapters 14, 15, 16, and 17).

cDNA (complementary DNA)

A DNA molecule synthesized in vitro from an mRNA template using the enzyme reverse transcriptase, containing only coding exon sequences.

Recombinant DNA

A synthetic or hybrid DNA molecule created by combining genetic material from two or more different biological sources in a laboratory.

Genomics

The comprehensive scientific study of entire genomes, including gene sequencing, structural organization, mapping, and evolutionary analysis.

Epigenetics

Heritable changes in gene expression and cellular phenotype that do not involve changes to the underlying nucleotide sequence of DNA.

Transformation

The mechanism of horizontal gene transfer in bacteria where exogenous genetic material is taken up directly from the surrounding environment.

Transduction

The transfer of host genetic material from one bacterium to another mediated by a bacteriophage (viral vector).

Transgenic Organism

An organism whose genome has been stably modified by the artificial introduction of exogenous DNA from a different species.

Plasmid

A small, circular, extrachromosomal DNA molecule found in bacteria that can replicate autonomously and is widely utilized as a cloning vector.

Codon

A continuous sequence of three nucleotides on an mRNA transcript that codes for a specific amino acid or acts as a translational stop signal.

Anticodon

A specialized three-nucleotide sequence on a transfer RNA (tRNA) molecule that binds complementarily and antiparallel to a corresponding mRNA codon.

Exon

A sequence within a eukaryotic pre-mRNA transcript that is retained following RNA splicing and remains in the mature mRNA to be translated into protein.

Intron

A non-coding intervening sequence in pre-mRNA that is excised and removed by the spliceosome before translation.

5' Methylated Cap

A modified 7-methylguanosine residue added to the 5' end of eukaryotic pre-mRNA that protects the transcript from enzymatic degradation and assists in ribosome attachment.

3' Poly-A Tail

A chain of adenine nucleotides appended to the 3' end of eukaryotic pre-mRNA that prevents nuclear degradation and facilitates mRNA export to the cytoplasm.

Alternative Splicing

A post-transcriptional gene regulation process where varying combinations of exons are included or excluded, allowing a single gene to encode multiple distinct protein isoforms.

Semiconservative Replication Model

The mode of DNA replication where each duplicated double helix contains one conserved parental strand and one newly formed daughter strand.

Antiparallel Orientation

The structural arrangement of complementary DNA strands where one strand runs in the 5' to 3' direction while the opposing strand runs in the 3' to 5' direction.

Leading Strand

The continuously synthesized nascent DNA strand that extends in the 5' to 3' direction toward the moving replication fork.

Lagging Strand

The discontinuously synthesized nascent DNA strand that extends in the 5' to 3' direction away from the replication fork, producing Okazaki fragments.

Ribozyme

An RNA molecule that exhibits catalytic enzyme activity, such as peptidyl transferase within the ribosome.

Restriction Enzyme

A bacterial endonuclease that recognizes specific palindromic DNA sequences and cleaves phosphodiester bonds, frequently producing staggered single-stranded 'sticky ends.'

Template Strand

The noncoding strand of DNA that is read in the 3' to 5' direction by RNA polymerase to synthesize a complementary mRNA transcript.

Release Factor (RF)

A protein that binds to the ribosomal A-site in response to a stop codon, causing hydrolysis of the ester linkage between the tRNA and polypeptide to terminate translation.

CAP/cAMP Complex

A transcriptional activator complex formed by catabolite activator protein and cyclic AMP that binds upstream of the promoter to enhance RNA polymerase binding when glucose is absent.

Polyribosome

A structure consisting of a single mRNA strand being translated simultaneously by multiple ribosomes to increase protein synthesis efficiency.

Proto-oncogene

A normal cellular gene that regulates cell growth, division, and differentiation, which has the potential to cause cancer when mutated into an oncogene.

TATA Box

A conserved, non-coding AT-rich promoter DNA sequence that assists in positioning the pre-initiation complex and RNA polymerase II in eukaryotic transcription.

Telomeres

Repetitive, non-coding nucleotide sequences at the ends of eukaryotic linear chromosomes that prevent chromosome degradation and progressively shorten with cell divisions.

Nucleosome

The fundamental repeating structural unit of eukaryotic chromatin, consisting of approximately 147 base pairs of DNA wrapped around an octamer of core histone proteins.

Operon

A functional genetic regulatory unit found in prokaryotes consisting of a cluster of co-regulated genes transcribed together under the control of a shared promoter and operator.

Operator

A regulatory DNA sequence within an operon where a repressor protein binds to physically obstruct RNA polymerase and block transcription.

Repressor

A regulatory protein that binds to an operator or silencer sequence to inhibit RNA polymerase activity, thereby reducing or preventing gene transcription.

Inducer

A small regulatory molecule that binds to and inactivates a repressor (or activates an activator), thereby triggering the transcription of an operon.

Polymerase Chain Reaction (PCR)

A molecular biology technique used to amplify specific target DNA sequences exponentially through repeating thermal cycles of denaturation, annealing, and extension.

Gel Electrophoresis

A laboratory method that separates charged biomolecules, such as DNA fragments or proteins, across an agarose or polyacrylamide matrix based on molecular size and charge.

CRISPR/Cas9

A targeted genome-editing system adapted from bacterial adaptive immunity that utilizes a single-guide RNA to direct the Cas9 endonuclease to introduce double-strand breaks at specific DNA sites.

Central Dogma of Biology

The core biological framework establishing that genetic information flows from DNA to RNA via transcription, and from RNA to protein via translation.

Xeroderma Pigmentosum (XP)

A rare genetic disorder characterized by a defective nucleotide excision repair pathway, resulting in an inability to repair ultraviolet-induced thymine dimers.

Wobble Effect

The flexible, non-standard base pairing between the 3rd nucleotide of an mRNA codon and the 1st nucleotide of a tRNA anticodon, allowing fewer tRNAs to translate degenerate codons.

Silent Mutation

A point mutation involving a single base substitution that changes a codon to a synonymous codon, producing no change in the amino acid sequence of the protein.

Missense Mutation

A point mutation in which a single base substitution alters a codon so that it codes for a different amino acid, potentially affecting protein folding and function.

Nonsense Mutation

A point mutation in which a single base substitution alters an amino acid-coding codon into a premature stop codon, yielding a truncated, non-functional polypeptide.

Frameshift Mutation

A mutation caused by the insertion or deletion of a number of nucleotides not divisible by three, shifting the translational reading frame and altering all subsequent amino acids.

p53 Gene Product

A crucial tumor suppressor transcription factor ('guardian of the genome') that initiates cell cycle arrest, DNA repair, or apoptosis in response to cellular stress and genomic damage.

Histone Acetylation

An epigenetic modification involving the addition of acetyl groups to lysine residues on histones, reducing chromatin compaction (forming euchromatin) to stimulate transcription.

DNA Methylation

The enzymatic addition of methyl groups to cytosine bases in DNA, typically leading to chromatin condensation (heterochromatin) and long-term transcriptional silencing.

Ubiquitination

A post-translational regulatory process where ubiquitin peptides are covalently attached to target proteins, marking them for degradation by the 26S proteasome.