DNA Replication:
Replication fork: A Y-shaped region where the new strands of DNA are elongating.
DNA polymerase: Elongation of new DNA at a replication fork is catalyzed by this enzyme.
Leading strand: DNA pol III can synthesize a complementary strand continuously by elongating the new
DNA in the 5'--->3' direction.
Lagging strand: the strand synthesized as a series of segments.
Okazaki fragments: The segments of the lagging strand are called Okazaki fragments.
DNA ligase: Joins (ligates) the sugar-phosphate backbones of the Okazaki fragments, forming a single new DNA strand.
Primer: Intiates the replication of the complementary strand, its a short stretch of RNA chain with an available 3' end.
Primase: An enzyme that starts an RNA chain to the start the complementary strand.
Helicase: An enzyme that untwists the double helix at the replication fork, separating the 2 parental strands making them available as template strands.
Topoisomerase: Helps relieve the strain as the untwisting causes strain ahead of the replication fork.
Single-strand binding protein: bind to the unpaired DNA strands, stabilizing them until they serve as templates for the synthesis of new complementary strands.
Nuclease: A segment of the strand containing the damage is cut out (excised) by a DNA-cutting enzyme, called nuclease.
DNA polymerase: Fills in the missing nucleotides excised by nuclease.
RNA:
Transcription: The synthesis of RNA under the direction of DNA.
Translation: The actual synthesis of a polypeptide, which occurs under the direction of mRNA. messenger RNA (mRNA): Carries a genetic message from the DNA to the protein-synthesizing machinery of the cell.
Ribosomes: Translate the base sequence of mRNA molecule into the amino acid sequence of polypeptide chain(s).
Primary transcript: The initial RNA transcript from any gene, this is called a primary transcript.

pre-mRNA(only in eukaryotes): The transcription of a protein-coding eukaryotic gene results in premRNA.
Codons: The mRNA base triplets are codons.
Triplet code: The genetic instruction for a polypeptide chain are written in the DNA as a series of nonoverlapping, 3-nucleotide words. Ex. AUG start codon.
Transcription:
RNA polymerase: Separates apart the two DNA strands and hooks together the RNA nucleotides as they base-pair along the DNA template.
Promoter: The sequence that signals the initiation of transcription by RNA polymerase on DNA strand, in prokaryotes.
Terminator: The sequence that signals the end of transcription.
Transcription unit: The stretch of DNA that is transcribed into an RNA molecule.
Transcription factors: In eukaryotes, a collection of proteins mediate the binding of RNA polymerase and the initiation of transcription.
Transcription Initiation Complex: The completed assembly of transcription factors and RNA polymerase II bound to the promoter.
TATA box: The crucial promoter in DNA sequence forming the initiation complex in eukaryotes.
RNA splicing: The removal of large portion of the RNA molecule that is initially synthesized.
Introns: The noncoding segments of nucleic acid that lie between coding regions.
Exons: Coding regions of DNA sequence. small nuclear ribonucleoproteins (snRNPs): Recognize segments of RNA that need to be spliced.
Spliceosome: Recognizes and interacts with certain sites along an intron, releasing the intron and joining together the two exons.
Ribozymes: RNA molecules that function as enzymes, by cutting themselves out. alternative RNA splicing: The variation of selection of exons on the same gene results different polypeptides chain (protein).
Domains: Proteins often have a modular architecture consisting of discrete structural and functional regions.

Translation: transfer RNA (tRNA): Transfers amino acids form the cytoplasmic pool of amino acids to a ribosome.
Anticodon: Base-pairs with a complementary codon on mRNA. aminoacyl-tRNA synthetase: Each amino acid is joined to the correct tRNA by a specific enzyme.
Wobble: The relaxation of the base-pairing rules. ribosomal RNA (rRNA): The ribosomal subunits are constructed of proteins and RNA molecules.
P site: Holds the rRNA carrying the growing polypeptide chain.
A site: Holds the tRNA carrying the next amino acid to be added to the chain.
E site: Discharged tRNA's leave the ribosome for the E site.
Polyribosomes: A number of ribosomes trail along one mRNA.
Signal peptide: Targets the protein to ER. signal-recongnition particle (SRP): An adapter that brings the ribosome to a receptor protein built into the
ER membrane.
Mutations: Changes in the genetic material of a cell.
Point mutation: Chemical changes in just one base pair of a gene. base-pair substitution: The replacement of one nucleotide and its partner with another pair of nucleotides.
Missense mutation: The altered codon still codes for an amino acid.
Nonsense mutation: Causes translation to be terminated prematurely.
Insertions and deletions: Additions or losses of nucleotide pairs in a gene.
Frameshift mutation: The number of nucleotides inserted or deleted is not a multiple of three.
Mutagens: A number of physical and chemical changes that cause mutations in DNA.