Unit 8: DNA, RNA, and Protein Synthesis

DNA

A molecule found in the cell nucleus that carries the genetic instructions for the growth, development, and reproduction of living things.

RNA

A single-stranded nucleic acid that copies instructions from genetic material and delivers them to ribosomes to build proteins.

Nucleotide

The basic building block of nucleic acids, consisting of a phosphate group, a sugar molecule, and a nitrogen base.

Double Helix

The twisted-ladder shape that forms the physical structure of a DNA molecule.

Gene

A specific section of DNA that codes for a specific protein and determines an inherited trait.

Chromosome

A tightly coiled bundle of DNA and proteins found inside the nucleus of eukaryotic cells.

Nitrogen Base

A nitrogen-containing molecule that forms the rungs of the nucleic acid ladder, pairing up to encode genetic information.

Adenine

The nitrogen base represented by the letter A that pairs with thymine in DNA and with uracil in RNA.

Thymine

The nitrogen base represented by the letter T that is found only in DNA and pairs with adenine.

Cytosine

The nitrogen base represented by the letter C that pairs with guanine in both DNA and RNA.

Guanine

The nitrogen base represented by the letter G that pairs with cytosine in both DNA and RNA.

Uracil

The nitrogen base represented by the letter U that is found only in RNA and pairs with adenine.

Replication

The biological process in which a cell makes an exact duplicate copy of its DNA before dividing.

Transcription

The step in the cell nucleus where a specific segment of DNA is copied into a complementary strand of messenger RNA.

Translation

The step at a ribosome where the genetic code in mRNA is read to link amino acids together into a chain.

Codon

A three-base sequence of nucleotides on an mRNA strand that specifies a single amino acid.

Anticodon

A three-base sequence on a tRNA molecule that pairs with a complementary three-base sequence on an mRNA strand.

Messenger RNA (mRNA)

The type of nucleic acid that carries genetic instructions from DNA in the nucleus out to the ribosomes in the cytoplasm.

Transfer RNA (tRNA)

The type of nucleic acid that brings the correct amino acids to the ribosome during protein construction.

Ribosomal RNA (rRNA)

The structural molecule that, along with proteins, makes up the organelle responsible for assembling amino acids.

Protein Synthesis

The overall two-stage cellular process—transcription and translation—that reads genetic instructions to assemble functional proteins.

Mutation

Any permanent change or error in the nucleotide sequence of an organism's DNA.