Amino Acid Structure
What is the monomer of a protein?
Amino acid
What type of reaction joins two amino acids?
Condensation
What do we call a long chain of amino acids?
A polypeptide
Which protein carries oxygen in red blood cells?
Hemoglobin
What is it called when a protein loses its shape?
Denaturation
What is the name of the NH₂ group on an amino acid?
Amino (amine) group
What molecule is released when two amino acids join?
Water
Where in the cell are polypeptides made?
At a ribosome (during translation)
Which protein is a structural part of hair and nails?
Keratin
What happens to a protein’s function when it is denatured?
It is lost
Which part of an amino acid is different in each of the 20 types, and what does it decide?
The R group (side chain). It determines the amino acid’s chemical properties.
A peptide bond forms between which two atoms?
The C of one amino acid’s carboxyl group and the N of the next amino acid’s amino group
Where is the amino acid sequence of a polypeptide stored?
In the base sequence of a gene
What are immunoglobulins and what do they do?
Antibodies made by white blood cells (B-cells). They bind to antigens on bacteria or pathogens.
Name two environmental changes that can denature a protein.
High temperature and a change in pH
Name the four things attached to the central carbon of an amino acid.
Hydrogen, amino group, carboxyl group, R group
Which parts are removed to make the water in a peptide bond reaction?
The –OH from the carboxyl group and the –H from the amino group
Name the two stages of protein synthesis and say what each one does.
Transcription copies the DNA code into mRNA. Translation changes the mRNA codons into a sequence of amino acids.
Where is rhodopsin found, and what happens when it absorbs light?
In the rod cells of the retina. It changes shape, which causes a nerve impulse to be sent to the brain.
Explain how heat denatures a protein.
Heat gives the molecules more kinetic energy, which breaks the weak bonds holding the protein’s shape. The polypeptide chains unfold and the 3D shape changes.
Every amino acid has an amino group and a carboxyl group. Explain why this allows them to link into long chains.
The carboxyl group of one amino acid can bond to the amino group of the next, so each one has a spot to join on at both ends.
A polypeptide has 10 amino acids. How many peptide bonds and how many water molecules were released?
9 peptide bonds and 9 water molecules
Explain why the number of possible polypeptides is infinite.
Compare collagen and keratin (number of polypeptides and where each is found).
Collagen has 3 polypeptides wound together like a rope. It’s found in skin, blood vessel walls, teeth, bones and tendons. Keratin has 2 polypeptide chains and is found in hair, nails, claws and hooves.
Explain how a change in pH denatures a protein and why this causes loss of function.
A pH change alters the attractions between R groups (it disrupts hydrogen bonds and can make ionic bonds disappear). This changes the 3D shape, and since shape determines function, the function is lost.