U4 bio

Central Dogma of Molecular Biology

Describes the flow of genetic information from DNA to RNA to protein: Transcription (DNA → mRNA) and Translation (mRNA → Protein).

Transcription

The process where DNA is transcribed into mRNA in the nucleus.

Translation

The process where mRNA is translated into protein at the ribosomes.

Semiconservative Replication

During DNA replication, each new strand consists of one old (template) strand and one newly synthesized strand.

Components of a Chromosome

DNA wrapped around histone proteins, forming nucleosomes, which condense into chromatin.

Origin of Replication

The specific location on DNA where replication begins.

Replisome

A complex of enzymes responsible for DNA replication.

Telomerase

An enzyme that extends the 3' ends of DNA to prevent loss of important genetic information.

Helicase

An enzyme that unwinds DNA strands at the replication fork.

DNA Ligase

An enzyme that joins Okazaki fragments on the lagging strand during DNA replication.

Capping of mRNA

Addition of a 5' cap for stability and export from the nucleus.

Polyadenylation

Addition of a poly-A tail at the 3' end of mRNA for protection and regulation.

Splicing of mRNA

Removal of introns to join exons, creating a mature mRNA sequence.

Genetic Code

The set of rules that relate sequences of nucleotides in mRNA to amino acids in protein synthesis.

Initiation in Translation

The assembly of small and large ribosomal subunits around the start codon.

Elongation in Translation

The process where tRNA brings amino acids to the ribosome, and peptide bonds form.

Termination in Translation

The process where the ribosome reaches a stop codon; release factors facilitate detachment of the polypeptide.

Positive Control of Gene Expression

Mechanism that enhances gene expression, increasing transcription rates.

Negative Control of Gene Expression

Mechanism that inhibits gene expression, decreasing transcription rates.

Operons

A cluster of genes controlled by a single promoter, allowing coordinated gene expression in prokaryotes.

Introns

Non-coding sequences removed during mRNA processing.

Exons

Coding sequences joined together during mRNA splicing to form a mature mRNA.

Ligand

A molecule that binds specifically to a receptor, initiating a cellular response.

Receptor Protein

A protein that receives signals from ligands, starting a cellular response.

Signal Transduction

The process by which a cell converts an external signal into a functional response.

Phosphorylation

The addition of a phosphate group to a molecule, often altering protein function.

Protein Kinases

Enzymes that transfer phosphate groups from ATP to specific substrates (usually proteins).

G Protein-Coupled Receptors

Receptors that interact with G proteins to transduce signals into cellular responses.