A.1.2 Nucleic Acids

Based on the 3rd edition biology textbook written by C.J. Clegg, Andrew Davis, Christopher Talbot

nucleotide

phosphate ester of a nucleoside - an organic base combined with pentose sugar and phosphate

cytosine

a pyrimidine nitrogenous base found in nucleic acids (DNA and RNA) that pairs with guanine

guanine

a purine nitrogenous base found in nucleic acids (DNA and RNA) that pairs with cytosine

adenine

a purine nitrogenous base found in the coenzymes ATP, NADP, and nucleic acids (DNA and RNA) that pairs with thymine

thymine

a pyrimidine nitrogenous base found in DNA that pairs with adenine

pentose

a 5-carbon monosaccaride sugar

condensation

formation of larger molecules involving the removal of water from smaller component molecules

purine

one of two types of chemical compounds used to make nucleotides building of DNA and RNA

ex: adenine and guanine

pyrimidine

one of two types of chemical compounds used to make nucleotides building of DNA and RNA

ex: thymine and cytosine in DNA

ex: uracil and cytosine in RNA

polynucleotide

a long, unbranched chain of nucleotides found in DNA and RNA

genetic code

sequence that dictates the order in which specific amino acids are assembled and combined to synthesize a protein; code lies in the DNA

codon

three consecutive bases in DNA or RNA which specify an amino acid

polymer

large organic molecules made up of repeating subunits (monomers)

uracil

a pyrimidine nitrogenous base found in RNA that pairs with adenine

messenger RNA (mRNA)

single-stranded ribonucleic acid formed by the process of transcription of the genetic code in the nucleus, which then moves to the ribosomes in the cytoplasm

transfer RNA (tRNA)

short lengths of RNA that combine with specific amino acids prior to protein synthesis

ribosomal RNA (rRNA)

molecule that forms part of the protein-synthesizing organelle also known as a ribosome

phosphodiester bond

the linkage between the 3’ carbon atom of one sugar molecule and the 5’ carbon atom of another nucleic acid

double helix

two interlocking helices joined by hydrogen bonds between the pairs of purine-pyrimidine bases (A pairs with T and G with C)

gene

heritable factor that consists of a length of DNA that codes for a protein

chromosome

length of DNA that carries specific genes in a linear sequence

locus

the particular position of a gene on homologous chromosomes

allele

different versions of the same gene

homologous chromosomes

pairs of chromosomes, one from each parent, that carry the same sequence of genes (but not necessarily the same alleles of those genes)

complementary base pairing

this describes how nitrogenous bases of nucleic acids align with each other in a specific way, complementary bases are held together by hydrogen bonds

genome

the whole of the genetic information of an organism or cell

mutations

a change in the amount or the chemical structure (ex: base sequence) of DNA of a chromosome

nucleosome

a sequence of DNA wound around eight histone protein cores - a repeating unit of eukaryotic chromatin

histone

protein (rich in the amino acids arginine and lysine) that forms the scaffolding of chromosomes and is used in chromosome condensation to form nucleosomes

non-histone chromosomal protein

proteins that remain in the chromatin once histone proteins have been removed; they play a key role in the regulation of gene expression

bacteriophage

a virus that parasitises bacteria (also known as a phage)

falsification

a process used by scientists in which a hypothesis is tested by trying to show that it is false; where a hypothesis cannot be shown false after repeated experiments conducted by different groups of scientists, it is considered a strong hypothesis