Chapter 12 and 13: DNA, RNA, and Proteins

base pairing

principle that bonds in DNA can form only between adenine and thymine and between guanine and cytosine (A=T; C=G) *same as Chargaff's rule

purine

a nitrogenous base that has a double-ring structure; either adenine or guanine

pyrimidine

a nitrogenous base that has a single-ring structure; thymine, cytosine, or uracil

antiparallel

referring to the arrangement of the sugar-phosphate backbones in a DNA double helix in opposite directions

semiconservative

the new DNA strand contain one side that is original and one side that is new

replication

process of copying DNA prior to cell division

DNA polymerase

principle enzyme involved in DNA replication

helicase

an enzyme that untwists the double helix and breaks the hydrogen bonds between nitrogenous base pairs

nucleotide

subunit of which nucleic acids are composed; made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base

RNA

single-stranded nucleic acid that contains the sugar ribose

messenger RNA (mRNA)

type of RNA that carries copies of instructions for the assembly of amino acids into proteins from DNA to the rest of the cell

ribosomal RNA (rRNA)

type of RNA that combines with proteins to form ribosomes

transfer RNA (tRNA)

type of RNA that carries each amino acid to a ribosome during protein synthesis

transcription

synthesis of an RNA molecule from a DNA template

RNA polymerase

enzyme that links together the growing chain of RNA nucleotides during transcription using a DNA strand as a template

promoter

specific region of a gene where RNA polymerase can bind and begin transcription

intron

sequence of DNA that is not involved in coding for a protein

exon

expressed sequence of DNA; codes for a protein

polypeptide

long chain of amino acids that makes proteins

codon

group of three nucleotide bases in mRNA that specify a particular amino acid to be incorporated into a protein

translation

process by which the sequence of bases of an mRNA is converted into the sequence of amino acids of a protein

anticodon

group of three bases on a tRNA molecule that are complementary to an mRNA codon

mutation

change in genetic material

terminator

specific region of a gene where RNA polymerase releases the RNA and stops transcription