Term | Definition |
Structure Proteins | Collagen and keratin make up skin, bone, hair, nails |
Catalysts Proteins | All reactions in living systems are catalyzed by enzymes |
Movement Proteins | Muscles are made up of myosin & actin |
Transport proteins | Hemoglobin transports O2 from the lung cells; other proteins transport molecules across cell membranes |
Hormone Proteins | Insulin, oxytocin, human growth hormone |
Protection Proteins | Blood clotting invloves protein fibrinogen; body uses antibodies to flight disease |
Storage Proteins | Casein in milk and ovalbumin in eggs store nutrients for newborn infants and birds; ferritin in the liver stores iron |
Regulation Proteins | Certain proteins control gene regulation and control where it takes place |
2 structural types of Proteins | 1. Fibrous Proteins-long & thin (structural)
2. Globular proteins- everything else (enzymes) |
Amino Acid | a compd that contains both an amino group and a carboxyl group
*in zwitterion form aa are solids with high melting points, water soluble |
a-amino acids | amino group is on the carbon adjacent to the carboxyl group |
Peptides | amide bond between the a-carboxyl group of one amino acid and the a-amino group of another |
Zwitterion Behavior | *at any pH above (basic) its pI, it has a negative charge
*Any pH below(acidic) its pI has a positive charge
*Proteins are least soluble in water at their isolelectric points and can be precipitated from solution at this pH |
# of peptides possible for a chain of n amino acids | 20^n |
Sickle Cell Anemia | a single subsitituion in one amino acid of the b-chain of hemoglobin |
a-Helix | *all R-groups point outward from helix
*C=O group of each peptide bond is H bonded to the N-H group of the peptide bond four amino acid units away from it
* the 6 atoms of each peptide bond lie in the same plane |
B-Pleated Sheet | * R groups alternate from above to below the plane of the sheet
*C=O and N-H groups of the peptide bonds from adjacent chains point toward each other are in the same plane so that the hydrogen bonding is possible between them |
Tertiary Structure | Overall conformation of an entire polypeptide chain |
Tertiary Structure is stabilized in 5 different ways | 1. Covalent bonds-formation of disfulide bonds between cysteine side chains
2. H Bonds- between polar groups of side chains
3. Salt Bridges- attraction of -NH3+ group and -COO group
4. Hydrophobic Interactions- between nonpolar side chains
5. metalion |
Quaternary Structure | arrangement of polpeptide chains into a noncovalently bonded to aggregation of protein subunits
* the individual chains are held together by h bonds, salt bridges, and hydrophobic interactions |
Adult Hemoglobin | 2 alpha chains of 141 aa each, and 2 betachains of 146 aa each |
Fetal Hemoglobin | 2 alpha chains and 2 gemma chains. has a great affinity for oxygen than adult hemoglobin |
Myoglobin | Storage in muscle; not allosterically |
Hemoglobin | allosterically regulated protein; transport |
Denaturation | process of destroying the native conformation of a protein by chemical or physical means; some reversible, some not
*agents insclude- Heat: can distrupt H bonding and unfold proteins |
Chaperone Proteins | heat shock proteins can assist proteins to attain their correct secondary and tertiary structure or facilitate the correct refolding of partially denatured proteins |
Which of the following is true of proteins? | the acid/base properties of a protein depends on the identity of its side chains |
What is true of the isoelectric point amino acids? | it is the pH at which amino acid has an equal number of positive and negative charges |
Secondary structure is associated with which of the following? | h-bonding within the backbone |
An example of a structural protein | Collagen |
How many proteins make up hemoglobin? | 4 |
Having the gene for sickle cell hemoglobin gives an individual enhanced immunity against what disease? | Malaria |
What type of chemical reaction is involved in the formation of disfulide bonds from thiolds? | oxidation |
How many atoms from the backbone of the repeat unit of a protein? | 6 |
Why is 70% ethanol rather than 95% ethanol used in sterilizing skin before injections? | kills bacteria by penetrating them and coagulating their proteins |
When will a protein have the lowest solubility? | at is isoelectric point |
How many different amino acids are commonly found in proteins? | 20 |
What is true of the atoms in the backbone unit of a protein? | they are all in the same plane |
What explains the unusually high melting points of amino acids? | their existence as zwitterions |
Protein synthesis proceeds in what direction? | from the N-terminus to the C-terminus |
What is the name for proteins which assist other proteins in attaining their correct secondary and tertiary structures? | Chaperones |
In the tertiary structure of proteins which aa is involved in forming covalent bonds? | cysteine |
What time of chemical reaction is involved in the conversion of disfulide bonds to thiols? | reduction |
What determines the characteristics of an aa? | the identity of its side chains |