Biology CH. 12 & 13 Vocab

Double Helix

two strands of nucleotides wound about each other; structure of DNA

Nucleotide

A building block of DNA, consisting of a five-carbon sugar covalently bonded to a nitrogenous base and a phosphate group.

Purine

Adenine and Guanine

Pyrimidine

Cytosine and Thymine

Chromatin

DNA and protein

Gene

A segment of DNA on a chromosome that codes for a specific trait

DNA replication

the process of making a copy of DNA

DNA Polymerase

Unzips DNA

RNA

single-stranded nucleic acid that contains the sugar ribose

Protein Synthesis

the formation of proteins by using information contained in DNA and carried by mRNA

DNA Transcription

the process of copying a section of DNA in order to make proteins

mRNA

messenger RNA; type of RNA that carries instructions from DNA in the nucleus to the ribosome

Introns

regions of DNA that do not code for proteins

Exons

Coding segments of eukaryotic DNA.

Codon

three-nucleotide sequence on messenger RNA that codes for a single amino acid

rRNA

ribosomal RNA; type of RNA that makes up part of the ribosome

Initiation

mRNA attaches to ribosome

tRNA

transfer RNA; type of RNA that carries amino acids to the ribosome

Anticodon

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

Elongation

addition of amino acids to the polypeptide chain; continues until it reaches a stop codon

Termination

the ribosome reaches a stop codon on the mRNA and protein synthesis stops.

Gene Mutation

a change in the base sequence of a gene

frameshift mutation

the mutation that causes the reading frame of mRNA codons to shift

point mutation

a mutation affecting only one or very few nucleotides in a gene sequence.