General Biology 2 Supplementary: DNA, Central Dogma, Mutations, and Genetic Engineering

Vocabulary flashcards covering key terms from DNA, transcription, translation, mutations, and genetic engineering.

DNA

Deoxyribonucleic acid; molecule that stores genetic information in all living cells and determines development and function.

Helicase

Enzyme that unwinds double-stranded DNA by breaking hydrogen bonds between bases to expose bases for replication.

Gyrase (Topoisomerase)

Enzyme that relieves supercoiling ahead of the replication fork to prevent over-winding of DNA.

SSBPs (Single-Stranded Binding Proteins)

Proteins that bind exposed single-stranded DNA to prevent re-annealing during replication.

Primase

Enzyme that synthesizes short RNA primers (about 8–12 nts) at the 3' end to initiate DNA synthesis.

DNA polymerase III

Main enzyme that adds nucleotides to the 3' end of a primer to synthesize the new DNA strand.

DNA polymerase I

Enzyme that removes RNA primers and fills in with DNA nucleotides.

Leading strand

DNA strand synthesized continuously in the 5'→3' direction using a single RNA primer.

Lagging strand

DNA strand synthesized discontinuously in short segments (Okazaki fragments) in 5'→3' direction.

DNA Ligase

Enzyme that seals nicks between DNA fragments by forming phosphodiester bonds.

Central Dogma

Concept: replication, transcription, translation describe the flow of genetic information from DNA to RNA to protein.

Replication

Process by which a DNA molecule is copied to produce two identical DNA molecules.

Transcription

Process by which a DNA segment is copied into an RNA transcript (mRNA).

Translation

Process by which ribosomes synthesize a polypeptide using the mRNA sequence and tRNA.

Promoter

DNA sequence that initiates transcription; nearby elements recruit RNA polymerase.

Pribnow box

Prokaryotic promoter consensus sequence: TATAAT.

Goldberg–Hogness box

Eukaryotic promoter consensus sequence; noted here as TATTAA.

Template strand

DNA strand read by RNA polymerase (3'→5') to synthesize RNA.

Coding strand

DNA strand not used for transcription; has sequence identical to the mRNA (T replaced by U in RNA).

mRNA

Messenger RNA; carries the genetic code from DNA to ribosomes for protein synthesis.

RNA polymerase

Enzyme that synthesizes RNA using a DNA template during transcription.

Chargaff’s rule

In DNA, amounts of A equal T and G equal C (A=T, G=C).

Start codon

AUG; initiates translation and encodes methionine.

Stop codons

UAA, UAG, UGA; signal termination of translation.

Codon

A three-nucleotide sequence in mRNA that encodes an amino acid or stop signal.

Degenerate genetic code

More than one codon can encode the same amino acid.

Shine-Dalgarno sequence

Prokaryotic ribosome-binding site; consensus AGGAGGU.

Kozak sequence

Eukaryotic translation initiation context; consensus GCCRCCAUGG.

tRNA

Transfer RNA; delivers specific amino acids to the ribosome during translation.

Ribosome

Ribonucleoprotein complex that reads mRNA codons and synthesizes the polypeptide chain.

Mutation

Heritable changes in DNA that can be neutral, beneficial, or harmful.

Gene mutation

Changes in chromosome structure or number (deletions, duplications, inversions, translocations).

Point mutation

Single base change in DNA; can be silent, missense, or nonsense.

Frameshift mutation

Insertion or deletion of nucleotides causing a shift in the reading frame.

Insertion

Addition of one or more nucleotides into DNA.

Deletion

Loss of one or more nucleotides from DNA.

Mutagens

Agents that induce mutations in DNA.

Base analogue

Chemicals resembling DNA bases that can be incorporated into DNA and cause mutations.

5-bromouracil

A base analogue that pairs with adenine (thymine analogue) and can cause mispairing.

Alkylating agents

Mutagens that add alkyl groups to DNA bases, causing mispairing.

Deaminating agents

Mutagens that remove amino groups from bases, causing mutations.

Intercalating agents

Mutagens that insert between base pairs, often causing frameshift mutations; e.g., Actinomycin-D.

Actinomycin-D

Intercalating anti-cancer drug that inserts between DNA bases.

Ionizing radiation

High-energy radiation (X-rays, gamma) that can break DNA strands.

Ultraviolet radiation

Non-ionizing radiation that forms thymine dimers, disrupting base pairing.

Thymine dimer

Covalent linkage of adjacent thymines caused by UV exposure; blocks replication.

Polycyclic aromatic hydrocarbons (PAH)

Environmental mutagens from combustion (cigarette smoke, exhaust).

Benzo[a]pyrene

Potent PAH carcinogen associated with increased lung cancer risk.

Heterocyclic amines (HCAs)

Mutagenic compounds formed when cooking meat at high temperatures.

Genetically modified organism (GMO)

Organism whose DNA has been altered using genetic engineering techniques.

Transgenic

GMO that contains genetic material from a different, unrelated species.

Cisgenic

GMO with genes from the same species or a closely related, sexually compatible species.

Intragenic

GMO containing genes from a crossable species; within-gene modifications.

Nuclear transplantation (SCNT)

Somatic cell nuclear transfer; transferring a donor nucleus into an enucleated egg to create embryos.

Stem cells

Cells capable of differentiating into multiple cell types; used in cloning and regenerative medicine.

Therapeutic cloning

SCNT to produce patient-specific embryonic stem cells for therapy, not reproduction.

Reproductive cloning

SCNT to produce a genetically identical organism; creates a clone.

GloFish

Transgenic fish engineered to express a fluorescent protein gene.

Arctic Apple

Genetically engineered apple that turns off PPO enzyme to resist browning.

Golden Rice

Rice engineered to synthesize beta-carotene (vitamin A precursor) to address deficiency.

Vector

Carrier DNA molecule used to deliver a gene into host cells.

Plasmid

Small circular DNA molecule used as a vector in bacteria.

Transformation

Process of introducing foreign DNA into cells, enabling genetic modification.

Exon

Coding sequences in a gene that remain in the mature mRNA after splicing.

Intron

Noncoding sequences that are removed during RNA processing (splicing).

Splicing

RNA processing step that removes introns and joins exons to form mature mRNA.

Nucleus

Cellular organelle that houses the genome in eukaryotes.

Genome

The complete set of genetic material in an organism; humans have 23 chromosome pairs.

Histones

Proteins around which DNA is tightly wound to form chromatin.

Griffith (1928)

Experiment showing transformation of R strain by S-type virulence factor; suggested a transferable 'transforming principle'.

Transforming principle

The substance responsible for transferring genetic information in Griffith's experiment; later identified as DNA.

Avery, MacLeod, McCarty (1944)

Showed DNA is the transforming principle by demonstrating that the transforming agent is nucleic acid–rich and not destroyed by proteases.

Hershey–Chase (1952)

Demonstrated that DNA, not protein, carries genetic information using labeled T2 phage in bacteria.

Chargaff (1950s)

Established A=T and G=C base-pair parity in DNA, supporting base-pairing rules.

Franklin (1950s)

X-ray diffraction studies (Photo 51) contributed crucial data for DNA’s double-helix structure.

Watson and Crick (1953)

Proposed the DNA double-helix model based on available data, winning the Nobel Prize.

Double helix

Two antiparallel DNA strands held together by complementary base pairing.

Thymine

Pyrimidine base in DNA that pairs with adenine; in RNA, thymine is replaced by uracil.