Key words to know

DNA

Deoxyribonucleic acid; the main storage system for genetic information in living cells, structured as a double helix made of nucleotide monomers using deoxyribose sugar.

RNA

Ribonucleic acid; used for various purposes within the cell, includes many types like mRNA, rRNA, tRNA; has a single-helix structure made from nucleotide monomers that use ribose sugar.

Nucleotide

The building block of DNA and RNA, consisting of three parts: phosphate, sugar, and nitrogenous base.

Complementary Base Pairing

The specific hydrogen bonding between nitrogenous bases where adenine bonds with thymine, and guanine bonds with cytosine in DNA.

Nitrogen Bases

Components that form the genetic code; include adenine, thymine, guanine, cytosine, and uracil, grouped as purines (adenine, guanine) and pyrimidines (cytosine, thymine, uracil).

Genes

Short stretches of DNA that code for specific proteins based on the sequence of nitrogenous bases.

Chromosomes

Structures formed during cell division when chromatin condenses, allowing DNA to be organized for mitosis.

Double Helix

The twisted ladder-like shape of DNA discovered by Rosalind Franklin, James Watson, and Francis Crick, with base pairs in the center and sugar-phosphate backbones.

Leading Strand vs. Lagging Strand

In DNA replication, the leading strand is replicated continuously, while the lagging strand is replicated in shorter fragments.

Replication

The process of creating an identical copy of DNA by splitting the double helix and using complementary base pairing.

Helicase

The enzyme responsible for unzipping the DNA double helix by breaking hydrogen bonds between base pairs during replication.

Primase

The enzyme that synthesizes RNA primers that signal DNA polymerase to begin DNA replication.

DNA Polymerase

The enzyme that assembles a new strand of DNA by adding complementary nucleotides to the existing DNA strand.

Ligase

The enzyme that connects newly synthesized DNA fragments by forming bonds in the sugar-phosphate backbone.

Transcription

The process of creating mRNA transcripts from a gene's DNA using RNA polymerase.

RNA Polymerase

The enzyme that synthesizes mRNA by using one strand of the gene’s DNA as a template.

mRNA

Messenger RNA that serves as a copy of the DNA sequence (with uracil replacing thymine) and transports the code to ribosomes.

Translation

The process of translating mRNA sequences into polypeptide chains at the ribosome.

Codon

A sequence of three bases on mRNA that corresponds to a specific amino acid, matched by tRNA anticodons.

Anticodon

A sequence of three bases on tRNA that is complementary to the codon on mRNA, matching amino acids during translation.

tRNA

Transfer RNA that delivers amino acids to ribosomes for protein synthesis.

Amino Acids

The building blocks of proteins that are linked together in chains to form polypeptides.

Ribosome

A complex of rRNA and proteins that translates mRNA into polypeptide chains.

Polypeptide Chain

A sequence of amino acids assembled by ribosomes that will fold into a functional protein.

Mutations

Changes in the DNA sequence that can lead to alterations in protein expression.

Frameshift Mutation

A genetic mutation caused by deletion or insertion of DNA that shifts the reading frame for codons.

Point Mutation / Substitution Mutation

A mutation affecting a single base pair, which can result in silent, missense, or nonsense mutations.