Module 5 Flashcards
Amino Acid
The building blocks of proteins.
Primary Structure
The sequence of amino acids in a protein.
Alpha Helix
The polypeptide backbone is twisted in a right-hand coil stabilized by hydrogen bonds.
Tertiary Structure
The overall three-dimensional shape of a protein, formed by interactions between secondary structures. Becomes a protein.
Translation
Converting mRNA to a polypeptide chain.
Ribosomes
A complex structure of RNA and protein that synthesizes proteins from amino acids as directed by the sequence of mRNA.
Codon
A group of three adjacent nucleotides in mRNA that specifies an amino acid in a protein or that terminates protein synthesis.
Reading Frame
Following a start codon, a consecutive sequence of codons for amino acids.
Aminoacyl tRNA Synthetases
An enzyme that attaches a specific amino acid to a specific tRNA molecule.
Start Codon
AUG.
Initiation (Translation)
AUG codon is recognized and Met is established as the first amino acid in the new polypeptide chain.
Elongation (Translation)
Successive amino acids are added one by one to the growing chain.
Termination (Translation)
The addition of amino acids stops and the completed polypeptide chain is released from the ribosome.
Release Factor
A protein that causes a finished polypeptide chain to be freed from the ribosome.
Polycistronic mRNA
A single molecule of messenger RNA that is formed by the transcription of a group of functionally related genes located next to one another along bacterial DNA.
Post-Translational Modification
A modification that occurs after translation. It regulates the structure and function of proteins.
Signal-Recognition Particle (SRP)
An RNA-protein complex that binds with part of a polypeptide chain and marks the assembly for delivery to the endoplasmic reticulum (eukaryotes) or the cell membrane (prokaryotes).
Peptide Bond
- CO - N
Secondary Structure
The level of protein structure resulting from regular and repeating hydrogen bonding interactions between atoms of the polypeptide backbone (α helix and β sheets).
Beta Sheet
The polypeptide chain folds back and forth on itself forming a pleated sheet stabilized by hydrogen bonds.
Quaternary Structure
The level of protein structure that results from the interactions of several different polypeptide chains (made up of different proteins).
mRNA
Messenger RNA.
A Site
Aminoacyl. The tRNA carrying the next amino acid binds.
P Site
Peptidyl. The tRNA carrying the polypeptide chain binds.
E Site
Exit. The empty tRNA binds and leaves.
Anticodon
The sequence of three nucleotides in a tRNA molecule that base pairs with the corresponding codon in an mRNA molecule.
tRNA
Transfer RNA. Noncoding RNA that carries individual amino acids for use in translation.
Genetic Code
The correspondence between codons and amino acids.
Stop Codon
UAA, UAG, or UGA.
Initiation Factors
A protein that binds to mRNA to initiate translation.
Gene Regulation
The various ways in which cells control gene expression.
Shine-Dalgarno Sequence
The initiation complex (initiation factors) is formed at one or more internal sequences present in the mRNA in prokaryotes.
Protein Sorting/Protein Targeting
The process by which proteins end up where they need to be in the cell to perform their functions.
Signal Sequences
An amino acid sequence in a protein that directs that protein to its proper cellular compartment.
Glycine
R group is hydrogen so it is not asymmetric. Is small and increases the flexibility of the protein which can be important in the folding of the protein.
Proline
R group is linked back to the amino group. It creates a kink or bend in the polypeptide chain and restricts rotation of the C-N bond, thereby imposing constraints on protein folding in its vicinity.
Cysteine
The -SH groups of two cysteines can form an S-S disulfide bond which covalently joins the side chains.
Disulfide Bonds (S-S)
Stronger than the ionic interactions of other pairs of amino acids and form cross-bridges that can connect different parts of the same protein or even different proteins.
Denaturation
The process by which molecules are unfolded and therefore lose their structure and function.
Chaperone Proteins
Help some proteins fold properly.
Initiation Code
AUG (codes for Met).
Elongation Factors
A protein that breaks the high-energy bonds of the molecule GTP to provide energy for ribosome movement and elongation of a growing polypeptide chain.
Operon
A group of functionally related genes located in tandem along the DNA and transcribed as a single unit from one promoter in prokaryotes.
Nuclear Localization Signals
A signal sequence that enables proteins to move through pores in the nuclear envelope.
Signal-Anchor Sequence
In protein sorting, an amino acid sequence in a polypeptide chain that embeds the chain in the membrane.
Protein Families
A group of proteins that are structurally and functionally related.
Folding Domain
A region of a protein that folds in a similar way across a protein family relatively independently of the rest of the protein.
Mutation
A change in the sequence of a gene.
Natural Selection
Variations in genes that led to increase chance of survival and reproduction are passed down while others die off.
Homodimer
A protein containing two identical subunits.
Heterodimer
A protein containing two non-identical subunits.
Uncharged
A tRNA without an amino acid attached.
Charged
A tRNA with an amino acid attached.
No Signal
Protein stays in cytosol.
Amino Terminal Signal
On the end. Protein goes to chloroplast or mitochondria.
Internal Signal
In the middle. Protein goes to the nucleus.
N-Terminus
The free amino group that is at the amino end of the peptide.
C-Terminus
The carboxyl group that is at the carboxyl end of the peptide.
Peptide
Two amino acids bonded together.
