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- author "Heidi"
- tags "chemistry"
- description "Keywords and concepts from chapter 14 of chemistry"
- fileName "Chemistry-chapter 14-proteins"
- freezingBlueDBID -1.0
- What are the 8 functions of proteins?
- Structure
- Catalysis - virtually all the reactions that take place in the living organisms are catalyzed by proteins called enzymes
- Movement - muscles are made up of proteins called myosin and actin
- Transport
- Hormones
- Protection
- Storage
- Regulation
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What are two important stuctural proteins?
Collagen and keratin
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What type of proteins catalyze reactions?
Enzymes
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What two proteins make up muscles?
Myosin and actin
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Name three hormones made up of proteins.
Insulin erythropoietin and human growth hormone
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What is a protein from an outside source or any other foreing substance called?
Antigen
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What are the proteins that the body makes to fight antigens called?
Antibodies
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What are the two main things that proteins regulate?
Gene expression (thereby regulating what proteins get synthesized in each cell) and when proteins get produced.
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What are the two major types of proteins?
Fibrous proteins and globular proteins
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Are fibrous proteins soluble in water?
No
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What are fibrous proteins mainly used for?
Stuctural purposes
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Are globular proteins soluble in water?
More or less (yes)
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What are globular proteins mainly used for?
Nonstructural purposes
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What are amino acids?
An organic compound containing an amino group and a carboxyl group.
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What is an alpha amino acid?
An amino acid in which the amino group is linked to the carbon atom next to the -COOH carbon.
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What are the four groups of amino acids?
- Nonpolar
- Polar but neutral
- Acidic
- Basic
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Which group (or groups) of amino acids are hydrophobic?
The nonpolar amino acids
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Which group (or groups) of amino acids are hydrophilic?
The polar but neutral acidic and basic amino acids
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Which amino acids are nonpolar (hydrophobic)?
Leucine, proline, alanine, valine,methionine, tryptophan, phenylalanine, and isoleucine.
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How many nonpolar amino acids are there?
Eight
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How many polar but neutral amino acids are there?
Seven
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What are the polar but neutral amino acids?
Glycine, serine, asparagine, glutamin, theronine, cysteine, and tyrosine.
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How many acidic amino acids are there?
Two
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What are the acidic amino acids?
Aspartic acid, and glutamic acid
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How many basic amino acids are there?
Three
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What are the basic amino acids?
Histadine, lysine, and arginine.
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Which of the twenty amino acids is achiral?
Glycine
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Which enantomer of amino acids is found in the body?
All of the proteins in your body (except for glycine, which is achiral) are the L-isomers.
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What are zwitterions?
Compounds that have a positive charge on one atom and a negative charge on another.
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Are amino acids zwitterions in both water solutions and the solid state?
Yes
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Are amino acids ionic compounds?
Yes
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Are all amino acids solids with high melting points?
Yes
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Are all twenty common amino acids fairly soluble in water?
Yes.
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What happens to a zwitterion (such as an amino acid) in a solution with a low pH?
The zwitterion becomes a positive ion.
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What happens to a zwitterion in a solution that has a high pH?
The zwitterion becomes a negative ion.
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What is an isoelectric point?
A pH at which a sample of amino acids or proteins has an equal number of positive and negative charges.
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How many of the twenty common amino acids have isoelectric points near six?
Fifteen
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What is an amphiprotic compound?
A compound that is both an acid and a base.
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What is a buffer solution?
A solution that neutralizes both acid and base.
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Are amino acid amphiprotic compounds?
Yes
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Are amino acids buffers?
Yes, aqueous solutions of them are buffers.
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What determines the functions of amino acids, and their polymers, and proteins?
The side chains of the amino acids.
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What amino acid has a chemical property not shared by any of the others?
What is the chemical property?
- The amino acid is cysteine.
- The chemical property is that it can be dimerized by many mild oxidizing agents.
- The dimer of cysteine is called cystine. Cystine, can be fairly easily reduced to give two molecules of cysteine.
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What is the bond between two amino acids(that contain sulfur) called?
A disulfied bond.
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Which three amino acids have basic side chains?
Histidine, lysine, and arginine.
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Which amino acids have aromatic rings in there side chains?
Tryptophan, phenylalanine, and tyrosine.
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Which amino acid is converted to serotonin?
Tryptophan
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Which amino acid is found in artificial sweeteners?
Phenylalanine
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Which amino acid has been known to make people sleepy?
Tryptophan
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Which amino acid has been known to give some people a "morning lift"?
Tyrosine
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What are the twenty common amino acids?
Alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, and valine.
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What two functional groups on amino acids are combined?
The carboxylic acid on one amino acid bonds to the amino group of the second amino acid and forms an amide.
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What type of bond is formed between two animo acids?
A peptide bond.
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What is the product of two amino acids being bonded together?
Dipeptide
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Can you add three amino acids together?
If yes what is the product?
Yes, the product is a tripeptide.
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What are peptides?
The shortest chain of amino acids.
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What are polypeptides?
Long chains of amino acids.
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What are proteins?
- Even longer chains of amino acids.
- A chain that contains at least 30-50 amino acids.
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What are amino acids in a chain often called?
Residues
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What is the c-terminus?
The amino acid at the end of a peptide that has a free alpha carboxyl group.
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What is the n-terminus?
The amino acid at the end of a peptide that has a free alpha amino group.
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Which side is the n-terminus written on?
The n-terminus is always written on the left.
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Is there freedom of rotation about the two bonds from the alpha carbon?
Yes
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Is there freedom of rotation of the carbon nitrogen bond?
No
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When are proteins least soluble in water?
At there isoelectric points.
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When can proteins be precipitated from their solutions?
At their isoelectric points.
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What are the four levels of organization in protein structure?
Primary structure, secondary structure, tertiary structure, and quaternary structure.
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What is primary structure?
The sequence of amino acids in a protein.
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What is secondary structure?
A repetitive conformation of the protein backbone.
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What are the two most common secondary structures?
Beta pleated sheet, and alpha helix
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What are random coils?
Those protein conformations that do not exhibit a repeated pattern.
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Describe the alpha helix.
A secondary structure where the protein folds into a coil held together by hydrogen bonds parallel to the axis of the coil.
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Describe the beta pleated sheet.
A secondary protein structure in which the backbone of two different molecules is held together by hydrogen bonds.
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What is tertiary structure?
The complete three dimensional arrangemant of the atoms in a protein.
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What are the five ways tertiary proteins are stabilized?
- Covalent bonds
- Hydrogen bonding
- Salt bridges
- Hydrophobic interactions
- Metal ion coordination
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Which type of covalent bond is most often involved in stabilizing tertiary structure?
Disulfide bonds
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What is a chaperone?
A protein that helps other proteins to fold into the biologically active conformation and enables partially denatured proteins to regain their biologically active conformation.
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What is the quaternary structure?
The spatial relationship and interactions between subunits in a protein that has more than one polypeptide chain.
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What are conjugated proteins?
Proteins that contain non-amino acids portions
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What is a prosthetic group?
The non-amino acid portion of a conjugated protein.
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What is the structure of hemoglobin?
Hemoglobin is made up of four chains two identical chains of 141 amino acid residues each and two identical beta chains 146 residues each.
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An estimated one third of all proteins are...?
Integral membrane proteins.
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What is denaturation?
The loss of the secondary, tertiary, and quaternary structures of a protein by a chemical or physical agent that leaves the primary intact.
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