Nucleic acids

Nucleic Acids

Polymers of subunits called nucleotides.

Nucleotide

A subunit of nucleic acids, composed of a phosphate group, a pentose sugar, and a nitrogenous base.

Phosphate Group

A chemical group consisting of a phosphorus atom bonded to four oxygen atoms, part of a nucleotide.

Pentose Sugar

A five-carbon sugar such as deoxyribose in DNA and ribose in RNA.

Deoxyribose

The sugar component of DNA nucleotides.

Ribose

The sugar component of RNA nucleotides.

Nitrogenous Base

A component of nucleotides; includes adenine, guanine, cytosine, thymine (in DNA), and uracil (in RNA).

Adenine

A purine nitrogenous base that pairs with thymine in DNA and uracil in RNA.

Thymine

A pyrimidine nitrogenous base found only in DNA, pairs with adenine.

Uracil

A pyrimidine nitrogenous base found only in RNA, pairs with adenine.

Purines

Nitrogenous bases with a double ring structure, including adenine and guanine.

Pyrimidines

Nitrogenous bases with a single ring structure, including cytosine, thymine, and uracil.

Polynucleotide Strand

A chain of nucleotides linked together via phosphodiester bonds.

5' Phosphate Group

The end of a DNA strand that has a phosphate attached to the fifth carbon of the sugar.

3' Hydroxyl Group

The end of a DNA strand that has a hydroxyl group attached to the third carbon of the sugar.

Phosphodiester Bond

A covalent bond that links nucleotides in a polynucleotide strand.

Hydrogen Bonds in DNA

Weak bonds that form between complementary nitrogenous bases, stabilizing the DNA double helix.

Antiparallel Orientation

The arrangement of the two DNA strands running in opposite directions.

Double Helix

The structural configuration of DNA, consisting of two intertwined strands.

Major and Minor Grooves

The spaces in the double helix of DNA, important for protein binding and interaction.

RNA Structure

Typically single-stranded, with ribose sugar and uracil instead of thymine.

Messenger RNA (mRNA)

RNA that carries genetic information from DNA for protein synthesis.

Transfer RNA (tRNA)

RNA that brings amino acids to the ribosome during protein synthesis.

Ribosomal RNA (rRNA)

RNA that forms the structural and functional components of the ribosome.

Friedrich Miescher

The scientist who discovered DNA in 1869, calling it nuclein.

Albrecht Kossel

Isolated the nitrogenous bases of DNA in 1878.

Phoebus Levene

Identified the components of nucleotides and proposed the tetranucleotide hypothesis.

Erwin Chargaff

Demonstrated that adenine equals thymine and cytosine equals guanine in a given DNA sample.

Hershey-Chase Experiment

Experiment that proved DNA is the genetic material using radioactive labeling.

Rosalind Franklin

Used X-ray crystallography to show that DNA is a double helix.

James Watson and Francis Crick

Developed the double helix structure of DNA based on previous research.

Chromosomes

Threadlike structures made of protein and DNA that carry genomic information.

Chromatin

A complex of DNA and proteins (histones) that forms chromosomes.

Nucleosome

A structure consisting of DNA wound around a core of histone proteins.

Heterochromatin

Condensed chromatin that is transcriptionally inactive.

Euchromatin

Extended chromatin that is transcriptionally active, high in gene concentration.

H1 Histone

A histone protein that helps link nucleosomes together.

DNA Packaging

The process of organizing DNA into structures that fit within the nucleus.

Nuclear Envelope

The double membrane surrounding the nucleus of eukaryotic cells.

Mitosis and Meiosis

Processes involving cell division where chromatin must be tightly packed into chromosomes.

Base Pair Rule

The principle that adenine pairs with thymine and cytosine pairs with guanine in DNA.

DNA Stabilization

The stability of DNA is ensured by pairing a double-ringed purine with a single-ringed pyrimidine.

Hydrophilic Backbone

The sugar-phosphate backbone of DNA that interacts with the aqueous environment.

Complementary Base Pairing

The specific hydrogen bonding between purines and pyrimidines in DNA.

DNA Sequencing

The process of determining the sequence of nucleotides in DNA.