BIOL 150 Chapter Notes - Chapter 4: Amine, Alpha Helix, Covalent Bond
Chapter 4: Summary
4.1 Proteins are linear polymers of amino acids that form 3D structures with specific
functions.
●An amino acid consists of a alpha carbon connected by covalent bonds to an amino
group, a carboxyl group, a hydrogen atom, and a side chain or R group.
●There are 20 common amino acids that differ in their R groups. Amino acids are
categorized by the chemical properties of their R groups---hydrophobic, basic, acidic
polar--and by special structures.
●Amino acids are connected by peptide bonds to form proteins.
●The primary structure of a protein is its amino acid sequence. The primary structure
determines how a protein folds, which in turn determines how it functions.
●The secondary structure of a protein results from the interactions of nearby amino acids.
Examples include the alpha helix and the beta sheet.
●The tertiary structure of a protein is its 3D shape, which results from long-range
interactions of amino acid R groups.
●Some proteins are made up of several polypeptide subunits; this group of subunits is the
protein’s quaternary structure.
●Chaperones help some proteins fold properly.
4.2 Translation is the process by which the sequence of bases in messenger RNA specifies
the order of successive amino acids in a newly synthesized protein.
●Translation requires many cellular components, including ribosomes, tRNAs, and
proteins.
●Ribosomes are composed of a small and a large subunit, each consisting of RNA and
protein; the large subunit contains 3 tRNA-binding sites that play different roles in
translation.
●An mRNA transcript of a gene has 3 possible reading frames composed of 3-nucleotide
codons.
●tRNAs have an anticodon that base pairs with the codon in the mRNA and carries and
specific amino acid.
●Aminoacyl tRNA synthetases attach specific amino acids to tRNAs.
●The genetic code defines the relationship between the 3-letter codons of nucleic acids and
their corresponding amino acids. It was deciphered using synthetic RNA molecules.
●The genetic code is redundant in that many amino acids are specified by more than one
codon.
●Translation consists of 3 steps: initiation, elongation, and termination.
Document Summary
4. 1 proteins are linear polymers of amino acids that form 3d structures with specific functions. An amino acid consists of a alpha carbon connected by covalent bonds to an amino group, a carboxyl group, a hydrogen atom, and a side chain or r group. There are 20 common amino acids that differ in their r groups. Amino acids are categorized by the chemical properties of their r groups---hydrophobic, basic, acidic polar--and by special structures. Amino acids are connected by peptide bonds to form proteins. The primary structure of a protein is its amino acid sequence. The primary structure determines how a protein folds, which in turn determines how it functions. The secondary structure of a protein results from the interactions of nearby amino acids. Examples include the alpha helix and the beta sheet. The tertiary structure of a protein is its 3d shape, which results from long-range interactions of amino acid r groups.
