Nucleic Acids and Protein Synthesis

Flashcards covering Nucleic Acids, DNA, RNA, Protein Synthesis, and Mutations.

Nucleic Acids

Complex chemicals that combine several different classes of smaller molecules. Unbranched polymers composed of repeating monomers called nucleotides joined by phosphodiester bonds.

DNA (Deoxyribonucleic Acid)

Stores the genetic information of an organism and transmits that information from one generation to another.

RNA (Ribonucleic Acid)

Translates the genetic information contained in DNA into proteins needed for all cellular function.

Nucleotides

Monomers that compose DNA and RNA and energy-rich compounds.

Nitrogenous Base

Heterocyclic aromatic amines that contain nitrogenous bases and are organic molecules made up of nitrogen-containing ring structures.

Pyrimidine

A 6-membered ring containing two nitrogen and four carbons, examples include Cytosine, Uracil, and Thymine.

Purine

A bicyclic structure containing four nitrogens and five carbons, examples include Adenine and Guanine.

Nucleoside

formed when a base is linked to a sugar molecule, usually D-ribose or D-2-deoxyribose by a β-N-glycosidic bond.

DNA

molecules contain several million nucleotides and the information stored in them is used to direct the synthesis of proteins.

Microsatellites

Simple sequence tandem repeats (SSTRs) that tend to occur in non-coding regions of the DNA.

BRCA gene

Tumor suppressor gene that helps repair DNA breaks that can lead to cancer and the uncontrolled growth of tumors.

RNA

Usually single stranded, found in the nucleus (but not in chromosomes) and in the cytoplasm, smaller than DNA, and the genetic material of RNA virus.

Ribosomal RNA (rRNA)

Provides the site where polypeptides are assembled during protein synthesis.

Messenger RNA (mRNA)

Carries the information from DNA to the ribosome.

Transfer RNA (tRNA)

Brings specific amino acids to the ribosomes for protein synthesis.

Non-Coding RNAs

Help regulate the expression of other genes.

Introns

Nucleotide sequences within a gene that do not code for amino acids.

Exons

Parts of the gene sequence that are expressed in the protein.

Primary Structure

A sequence of nucleotides consisting of the backbone of the molecule and the bases that are the side-chain group.

Secondary Structure

DNA consists of two polynucleotide strands that wind into a right-handed double helix.

Chargaff’s Rule

If Adenine and Thymine. ( Guanine and Cytosine) are present in equimolar quantities.

Higher-order Structure

DNA molecules are coiled around basic protein molecules called histones combining to form nucleosomes.

Replication

The process by which DNA makes a copy of itself when a cell divides.

Topoisomerase

Enzymes that relax the supercoiling in DNA strands and unwinds DNA only.

Helicase

Enzymes that separate the nucleic acid strands for replication.

DNA Primase

Synthesizes RNA primers complementary to the DNA strand. Short fragments of RNA that initiate the synthesis of new strand.

DNA Polymerase

Adds nucleotides one by one to the growing DNA chain.

Ligase

Seals the gaps between DNA fragments and Links Okazaki fragments.

Exonuclease

Removes RNA primers and nucleotide bases from the end of a DNA chain

Transcription

The synthesis of mRNA from DNA.

RNA polymerases

Enzymes that transcribe DNA into RNA using a DNA template to build a new RNA molecule through base pairing.

Initiation

The beginning of transcription where transcription factors bind to the promoter to help RNA polymerase attach to the DNA

Elongation

The addition of nucleotides to the mRNA strand where RNA polymerase reads the unwound DNA strand and builds the mRNA molecule, using complementary base pairs.

Termination

Sequences called terminators signal that the RNA transcript is complete.

Translation

The synthesis of proteins from RNA.

Mutation

A change in the nucleotide sequence in a molecule of DNA.

Point Mutation

The substitution of one nucleotide for another.

Missense

Changes the codon so that it corresponds to a different amino acid.

Nonsense

Changes the codon so that it signals an early stop of translation.

Phenylketonuria (PKU)

An inherited error of metabolism caused by a deficiency in the enzyme phenylalanine hydroxylase.

Duchenne Muscular Dystrophy

A genetic disorder characterized by progressive muscle degeneration and weakness due to the alterations of a protein called dystrophin that helps keep muscle cells intact.

Deletion Mutation

Occurs when one or more nucleotides is/are lost from a DNA molecule.

Insertion Mutations

Occurs when one or more nucleotides is/are added to a DNA molecule.

Huntington’s Disease

An inherited disorder that causes nerve cells (neurons) in parts of the brain to gradually break down and die.

Mutagens

A chemical or physical phenomenon that promotes errors in DNA replication.

Carcinogens

Associated with carcinogenesis and tumor formation.

Clastogens

Associated with chromosomal abnormalities (deletion, rearrangement)

Teratogens

Associated with a congenital malformations