Learn: Proteins and Nucleic Acids | Quizlet

Protein

A functional biological molecule made of one or more folded polypeptides.

Polypeptide

A polymer made of amino acids linked together.

Amino acid

The monomer, or basic building block, of a protein.

Four groups attached to an amino acid's alpha carbon

A hydrogen, carboxyl group, amino group, and functional R group.

R group (side chain)

The variable part of an amino acid that determines its chemical properties.

Peptide bond

The covalent bond that joins one amino acid to another in a polypeptide.

Protein dehydration reaction

Joins amino acids by removing water and forming a peptide bond.

Nonpolar amino-acid side chain

A hydrophobic R group that does not interact well with water.

Polar amino-acid side chain

A hydrophilic R group that interacts with water.

Electrically charged side chain

A hydrophilic R group carrying a positive or negative charge.

Acidic vs. basic amino acids

Acidic side chains are negatively charged; basic side chains are positively charged.

Primary protein structure

The specific order of amino acids in a polypeptide.

Secondary protein structure

Localized folding of a polypeptide into alpha helices or beta-pleated sheets.

What stabilizes secondary protein structure?

Hydrogen bonds along the polypeptide backbone.

Tertiary protein structure

The final three-dimensional shape of one polypeptide chain.

Quaternary protein structure

The final three-dimensional protein formed when multiple polypeptide chains join.

Why does protein shape matter?

A protein's shape determines how it functions.

Major protein functions

Enzymes, storage, communication, structure, movement, immune defense, transport, and receptors.

Nucleic acid

A polymer of nucleotide monomers that stores or carries biological information.

Three parts of a nucleotide

A phosphate group, five-carbon sugar, and nitrogenous base.

Sugar in DNA vs. RNA

DNA contains deoxyribose; RNA contains ribose.

Ribose vs. deoxyribose

Ribose has an OH at the 2′ carbon; deoxyribose has H there and one less oxygen.

Purines

Two-ring nitrogenous bases: adenine and guanine.

Pyrimidines

One-ring nitrogenous bases: cytosine, thymine, and uracil.

Bases found in DNA

Adenine, thymine, cytosine, and guanine: A, T, C, and G.

Bases found in RNA

Adenine, uracil, cytosine, and guanine: A, U, C, and G.

Phosphodiester bond

The covalent sugar-phosphate link formed when nucleotides join through a dehydration reaction that releases water.

Sugar-phosphate backbone

The repeating chain of sugars and phosphates on the outside of DNA or RNA.

Typical RNA structure

A single nucleotide strand containing ribose and uracil.

DNA structure

Two nucleotide strands twisted into a double helix.

What holds DNA's two strands together?

Hydrogen bonds between complementary nitrogenous bases.

Complementary DNA base pairs

Adenine pairs with thymine; cytosine pairs with guanine.

Antiparallel DNA strands

The two DNA strands run in opposite directions.

Main function of nucleic acids

Carry information needed for growth, development, and reproduction.

Central dogma

Biological information normally flows from DNA to RNA to protein.

Transcription

The transfer of information from DNA to RNA.