DNA, Replication, Mutations, and Protein Synthesis

Comprehensive vocabulary flashcards covering DNA structure, replication enzymes and stages, telomeres, types of mutations, and protein synthesis concepts.

DNA Nucleotide

The basic building block of DNA consisting of three parts: a phosphate group, a deoxyribose sugar, and a nitrogenous base (A, T, C, or G).

Nitrogenous Bases (DNA)

The four chemical bases found in DNA: Adenine (A), Thymine (T), Cytosine (C), and Guanine (G).

DNA Backbone

The outer structural frame of DNA formed by alternating phosphate groups and deoxyribose sugars.

Complementary Base-Pairing Rules (DNA)

The base-pairing specification in DNA where Adenine (A) pairs with Thymine (T), and Cytosine (C) pairs with Guanine (G).

Antiparallel

Describes DNA strands running in opposite directions, with one strand running $5' \rightarrow 3'$ and the other running $3' \rightarrow 5'$.

DNA vs. RNA

DNA contains deoxyribose, thymine, is usually double-stranded, and stores genetic information; RNA contains ribose, uracil, is usually single-stranded, and assists with protein synthesis and other functions.

mRNA, tRNA, and rRNA

The three main types of RNA in protein synthesis: mRNA carries instructions, tRNA brings amino acids, and rRNA forms part of ribosomes and helps catalyze peptide bonds.

Pyrimidines

Single-ring nitrogenous bases consisting of Cytosine (C), Thymine (T), and Uracil (U).

Purines

Double-ring nitrogenous bases consisting of Adenine (A) and Guanine (G).

Nucleosomes

Structural units formed when DNA wraps around histone proteins; they organize to form chromatin, which condenses into chromosomes.

Histones

Proteins that DNA wraps around to help package and organize DNA inside a eukaryotic nucleus.

Chromosome

A DNA molecule associated with proteins that contains genetic information.

S Phase (Synthesis Phase)

The stage of interphase within the cell cycle during which DNA replication occurs.

DNA Helicase (unzip)

The enzyme that unwinds the double helix and separates the two DNA strands by breaking hydrogen bonds.

Primase

The enzyme that synthesizes short RNA primers to provide a starting point for DNA polymerase.

DNA Polymerase (Zip)

An enzyme that adds complementary DNA nucleotides to build a new strand in the $5' \rightarrow 3'$ direction and frequently performs proofreading.

DNA Ligase (Glue)

The enzyme that seals gaps in the sugar-phosphate backbone and joins Okazaki fragments together.

Initiation (Replication)

The initial stage of replication where DNA unwinds at an origin, a replication fork forms via helicase, and primase creates RNA primers.

Elongation (Replication)

The stage of replication where DNA polymerase adds complementary nucleotides, creating a continuous leading strand and a lagging strand made of Okazaki fragments.

Termination (Replication)

The concluding step of replication in which RNA primers are removed and replaced with DNA, ligase seals gaps, and two DNA molecules result.

Leading Strand vs. Lagging Strand

The leading strand is synthesized continuously toward the replication fork, whereas the lagging strand is synthesized discontinuously away from the fork.

Okazaki Fragments

Short DNA segments synthesized discontinuously on the lagging strand.

Telomeres

Repeated DNA sequences located at chromosome ends that protect chromosome integrity and prevent loss of vital DNA during replication.

Telomerase

An enzyme that extends telomeres by adding repeated DNA sequences using its own RNA template.

Mutation

A permanent change in the nucleotide sequence of DNA.

5′ Cap

A modified guanine nucleotide attached to the $5'$ end of eukaryotic mRNA that provides protection and aids in ribosome recognition.

Poly-A Tail

A sequence of adenine nucleotides appended to the $3'$ end of eukaryotic mRNA to promote mRNA stability.

Start Codon

AUG; the codon that specifies methionine and signals the start of translation.

Stop Codons

The codons UAA, UAG, and UGA, which signal the termination of translation.

Translation

The protein synthesis process occurring in three stages: initiation (ribosome assembles), elongation (amino acids join), and termination (stop codon is reached and protein releases).