Nucleic Acids

DNA

The genetic material of the cell that carries the hereditary information.

Protein

A macromolecule composed of amino acids that performs various functions in the cell.

Genetic Material

The material responsible for transferring hereditary information from one generation to the next.

Isotopic Mediums

Different growth mediums containing radioactive isotopes used to label specific viral components.

Radiolabelled Proteins

Proteins that have been labeled with a radioactive isotope.

Radiolabeled DNA

DNA that has been labeled with a radioactive isotope.

Centrifugation

A process of separating particles based on their size and density using centrifugal force.

Supernatant

The liquid portion that remains after centrifugation.

Bacterial Pellet

The solid portion that forms at the bottom of a centrifuge tube after centrifugation.

X-ray Diffraction

A method used to study the structure of molecules by analyzing the scattering pattern of X-rays.

Molecular Structure

The arrangement and organization of atoms in a molecule.

Double Helix

The twisted ladder-like structure formed by two strands of DNA.

Antiparallel

Referring to the opposite orientation of the two strands of DNA in a double helix.

Complementary Base Pairing

The specific pairing of nitrogenous bases in DNA (A with T, G with C).

DNA Replication

The process of copying DNA to produce two identical DNA molecules.

Helicase

An enzyme that unwinds and separates the double-stranded DNA during replication.

DNA Gyrase

An enzyme that reduces the torsional strain created by helicase during DNA unwinding.

Single Stranded Binding (SSB) Proteins

Proteins that bind to separated DNA strands to prevent re-annealing.

DNA Primase

An enzyme that synthesizes a short RNA primer on each template strand during replication.

DNA Polymerase III

An enzyme that adds nucleotides to the 3'-end of a primer during DNA replication.

Leading Strand

The strand of DNA that is synthesized continuously in the same direction as DNA unwinding.

Lagging Strand

The strand of DNA that is synthesized discontinuously in the opposite direction of DNA unwinding.

Okazaki Fragments

Short DNA fragments synthesized on the lagging strand during DNA replication.

DNA Polymerase I

An enzyme that removes RNA primers and replaces them with DNA nucleotides during replication.

DNA Ligase

An enzyme that joins the Okazaki fragments together to form a continuous DNA strand.

DNA Sequencing

The process of determining the order of nucleotides in a DNA molecule.

Dideoxynucleotides (ddNTPs)

Nucleotides lacking a 3'-hydroxyl group, used to terminate DNA replication during sequencing.

Gel Electrophoresis

A technique used to separate DNA fragments based on their size using an electric field.

Non-Coding DNA

DNA sequences that do not code for proteins but have other important functions.

Satellite DNA

Long stretches of DNA made up of repeating elements called short tandem repeats (STRs).

DNA Profiling

A technique used to identify individuals based on their unique DNA profiles.

Nucleosome

A complex formed by DNA wrapped around a core of histone proteins.

Chromatin

The condensed form of DNA and associated proteins in the nucleus of a cell.

Gene

A sequence of DNA that is transcribed into RNA and contains a promoter, coding sequence, and terminator.

RNA polymerase

Enzyme that binds to the promoter and separates DNA strands during transcription.

Coding sequence

Region of DNA that is transcribed by RNA polymerase.

Terminator

Sequence that signals the end of transcription.

Antisense strand

DNA strand that is transcribed into RNA and is complementary to the RNA sequence.

Sense strand

DNA strand that is not transcribed into RNA and has the same sequence as the RNA except for T instead of U.

Transcription

Process of copying a DNA sequence into a complementary RNA sequence.

Capping

Addition of a methyl group to the 5'-end of transcribed RNA to protect it from degradation and facilitate recognition by the cell's translational machinery.

Polyadenylation

Addition of a poly-A tail to the 3'-end of the RNA transcript to improve stability and facilitate export from the nucleus.

Splicing

Removal of non-coding introns from the RNA transcript and fusion of coding exons to form mature mRNA.

Alternative splicing

Selective removal of specific exons, resulting in the formation of different polypeptides from a single gene sequence.

Transcription factors

Proteins that bind to the promoter and mediate RNA polymerase binding and initiation of transcription.

Regulatory proteins

Proteins that bind to DNA sequences outside of the promoter and interact with transcription factors to regulate gene expression.

Control elements

DNA sequences that regulatory proteins bind to, including proximal elements close to the promoter and distal elements further away.

Heterochromatin

Supercoiled DNA that is not accessible for transcription.

Euchromatin

Loosely packed DNA that is accessible for transcription.

DNA methylation

Addition of methyl groups to DNA, which can affect gene expression by preventing the binding of transcription factors.

Epigenetics

Study of changes in phenotype as a result of variations in gene expression levels.

Ribosomes

Complexes of protein and ribosomal RNA that carry out protein synthesis.

Transfer RNA (tRNA)

Molecules that carry amino acids to the ribosome during translation.

Initiation

Assembly of mRNA, tRNA, and ribosome to start translation.

Elongation

Addition of amino acids to the growing polypeptide chain during translation.

Translocation

Movement of the ribosome along the mRNA strand during translation.

Termination

Disassembly of the ribosome and release of the polypeptide chain at the stop codon.

Polysomes

Groups of two or more ribosomes translating an mRNA sequence simultaneously.

Signal sequence

Sequence on a nascent polypeptide chain that determines its destination within the cell.

Translation

The process of protein synthesis where the polypeptide chain grows in the endoplasmic reticulum (ER) through a transport channel.

Vesicle

A small membrane-bound sac that transports proteins from the ER to the Golgi complex or lysosome.

Integral proteins

Proteins targeted for membrane fixation that become embedded in the ER membrane.

Signal sequence

A specific sequence of amino acids that directs the protein to the ER and is cleaved once the polypeptide is fully synthesized.

Primary structure

The sequence of amino acids in a protein, formed by covalent peptide bonds.

Secondary structure

The folding of a polypeptide into α-helices and β-pleated sheets due to hydrogen bonding.

Tertiary structure

The overall 3D shape of a protein, formed by interactions between R groups.

Quaternary structure

The arrangement of multiple polypeptides or prosthetic groups to form a larger, biologically active protein.