Unit 6: Gene Expression and Regulation (copy)

unit 6 ap bio

Nucleotide

The building block (monomer) of DNA and RNA, consisting of a phosphate group, a five-carbon sugar, and a nitrogenous base.

Deoxyribose

The sugar found in DNA, distinguishing it from ribose in RNA.

Ribose

The sugar found in RNA.

Purines

Nitrogenous bases with a double-ring structure; includes adenine (A) and guanine (G).

Pyrimidines

Nitrogenous bases with a single-ring structure; includes cytosine (C), thymine (T), and uracil (U).

Phosphodiester bond

The covalent bond linking nucleotides, forming the sugar-phosphate backbone of nucleic acids.

5′ end

The end of a nucleic acid strand with a free phosphate group on the 5′ carbon.

3′ end

The end of a nucleic acid strand with a free hydroxyl group on the 3′ carbon.

DNA

Typically double-stranded, optimized for long-term information storage.

RNA

Usually single-stranded, optimized for flexible roles in gene expression.

mRNA

Messenger RNA; a temporary RNA copy of a gene that is translated into a protein.

rRNA

Ribosomal RNA; a structural and catalytic component of ribosomes.

tRNA

Transfer RNA; brings amino acids to the ribosome by matching anticodons to codons.

Base pairing

The predictable pairing of nitrogenous bases in DNA: A with T and C with G.

Double helix

The structure formed by two strands of DNA coiled around each other.

Gene

A segment of nucleic acid that encodes information to produce a functional product.

Genome

All the genetic material contained within an organism.

Chromosome

A discrete unit of DNA that comprises the genome.

Plasmid

A small, double-stranded, circular DNA molecule found in prokaryotes.

Semi-conservative replication

The method of DNA replication where each new molecule has one original strand and one new strand.

Helicase

An enzyme that unwinds the DNA double helix during replication.

DNA polymerase

An enzyme that synthesizes new DNA strands by adding nucleotides.

Leading strand

The DNA strand synthesized continuously toward the replication fork.

Lagging strand

The DNA strand synthesized discontinuously away from the replication fork in segments called Okazaki fragments.

Okazaki fragments

Short segments of DNA synthesized on the lagging strand during DNA replication.

Telomeres

Repetitive structures at the ends of linear DNA that protect coding regions during replication.

Mutation

A change in the nucleotide sequence of DNA, which can affect protein function.

Point mutation

A mutation that involves the substitution of a single nucleotide.

Frameshift mutation

A mutation caused by insertions or deletions that shift the reading frame of the genetic message.

Transduction

The process of transferring genetic material from one bacterium to another via a virus.

CRISPR-Cas9

A genome editing tool that allows for targeted modifications to DNA.

Gel electrophoresis

A technique used to separate DNA or RNA fragments by size.

A site

The aminoacyl-tRNA site on the ribosome where tRNA carrying amino acids enters.

P site

The peptidyl-tRNA site on the ribosome where the tRNA holding the growing polypeptide chain is located.

E site

The exit site on the ribosome where empty tRNA exits after its amino acid has been added to the polypeptide chain.