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Ch. 22 Proteins
| 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 |
Created by:
aoyler
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