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Exam 2
Exam 2 CSUB Pawluk
68
Chemistry
Undergraduate 3
10/23/2012

Additional Chemistry Flashcards

 


 

Cards

Term
[image]
Definition
  • Uracil
  • pyrimidine
  • nucleoside name uridine 
Term
[image]
Definition
  • thymine
  • pyrimidine
  • nucleoside name thymidine 
Term
[image]
Definition
  • cytosine
  • pyrimidine
  • nucleoside name  cytodine
Term
[image]
Definition
  • Adenine
  • purine
  • nucleoside name adenosine
Term
[image]
Definition
  • guanine
  • purine
  • nucleoside name guanosine
Term
example of a primary protein structure
Definition
a polypeptide chain
Term
example of a secondary protein structure
Definition

the helix

the pleated sheet

Term
an example of a tertiary protein structure
Definition
myoglobin with heme
Term
which bonds are broken during protein hydrolysis
Definition
amide bonds
Term
Which bonds and/or attractions are affected by denaturation
Definition

hydrogen bonds

ionic attractions

hydrophobic interactions

disulfide bridges

Term
What is true about denaturation?
Definition
  • a denatured protein has a different tertiary structure than its native state
  • egg white meringue contains denatured proteins
  • soakin fish in lime juice to make ceviche denatures the proteins 
  • digestive enzymes hydrolyze proteins
Term
What are the characteristics of enzymes?
Definition
  • an enzyme yields a specific product, whereas a nonbiological catalyst may produce more than one product, and side reactions may occur
  • a sustrate must bind to the active site before a reaction occurs
  • an enzyme is specific for a substrate
  • reactions occure at the active site, which usually consists of a crevice on the surface of the enzyme
Term
Describe lock-and-key model of an enzyme.
Definition
  • enzyme atcive site has a rigid structure complementary to that of the substrate 
Term
describe the induced-fit model of an enzyme.
Definition
enzyme conformation changes when it binds the substrate so the active site fits the substrate
Term
what happens to an amino acid at pH<isoelctric pH (pI)?
Definition

the carboxylate anion picks up a proton (COO- becomes COOH)

 

Term
what are nucleic acids?
Definition
  • unbranched polymers composed of repeating monomers called nuleotides
  • DNA and RNA are nucleic acids

 

Term
What are some common characteristics of induced-fit and lock-and-key models of enzymes?
Definition
  • substrate binds to the enzyme at the active site, forming an enzyme-substrate complex
  • substrate binds to the enzyme through noncovalent interactions 
Term
describe competitive inhibitor
Definition
  • inhibitor structure resembles substrate structure
  • inhibitor does not alter the maximum reaction rate
Term
describe a non-competitive inhibitor
Definition
  • inhibitor distorts the shape of the enzyme
  • inhibitor binds noncovalently at other than active site 
Term
What is the role of mRNA
Definition
messenger RNA carries the information from DNA to the ribosome
Term
[image]
Definition
  • the monosaccharide present in DNA
  • beta-furanose form 
Term
What are the structural features of a purine?
Definition
  • contain two heterocyclic rings
  • contain four ting nitrogens 
Term
what are the structural features of a pyrimidine?
Definition
  • contains one heterocyclic ring
  • contains only two ring nitrogens
Term
What is a phosphoester bond?
Definition

P—O—C

 

Term
what is a phosphoanhydride bond?
Definition
P—O—P
Term
What is a phosphoanhydride bond?
Definition
P—O—P
Term
Replication
Definition
  • both DNA strands are duplicated
  • semi-conservative
  • uses DNA polymerase
Term
transcription
Definition
single DNA strand is used to produce mRNA
Term
translation
Definition
  • amino acids added to peptide chain
  • requires tRNA
  • ribosomes 
  • RNA to protien
Term
In which dirction does replication occur?
Definition
3' end to the 5' end
Term
tRNA
Definition
  • anticodon
  • smallest RNA molecule
  • transports amino acids 
Term
mRNA
Definition
  • carries genetic information from nucleus to cytoplasm 
  • contains the sequence of codons that determines the order of amino acids in the protein
  • initiation begins with mRNA bindind to the ribosome
Term
rRNA
Definition
combines with protein to form ribosomes
Term

Describe silent mutation and give examples

Definition
  • the new codon codes for the same amino acid
    • substitution of one base: a codon is changed from UAU to UAC
    • a base substitution does not have any noticeable effects 
Term
Describe a missense mutation and give examples.
Definition
  • the new codon codes for a different amino acid
    • substitution of one base: a codon is changed from GAG to GUG
    • substitution of one base: a codon is changed from CAC to CGC
    • a person makes a protein of normal length but with altered function 
Term
describe a nonsense mutation and give examples
Definition
  • the new codon is a stop codon
    • subtitution of UGA for a codon
    • a person makes a truncated, nonfunctional protein 
Term

Name the basic amino acids

 

Definition
  • Arginine - Arg - R - essential
  • Histidine - His - H - essential
  • Lysine - Lys - K - essential
Term
Name the acidic amino acids
Definition
  • Aspartic acid - Asp - D
  • Glutamic acid - Glu - E 
Term
What are the essential amino acids?
Definition
  • Isoleucine
  • leucine
  • methionine
  • phenylalanine
  • threonine
  • tryptophan
  • valine
  • arginine
  • histidine
  • lysine 
Term
Myoglobin
Definition
stores oxygen in the tissues
Term
myosin
Definition
controls muscle contractions
Term
What is the role of rRNA?
Definition
ribosomal RNA provides the site where polypeptides are assembled during protein synthesis
Term
simplest amino acid
Definition
glycine
Term
What determines an L- or D-amino acid?
Definition
If the amide group is on the left then it is an L-amino acid
Term
What is the charge of an amino acid at a pH equal to its pI?
Definition
neutral
Term
what is the charge of an amino acid ant a pH below its pI?
Definition
positive
Term
What is the charge on an amino acid at a pH above its pI?
Definition
negative
Term
What is the strongest type of interaction between two cysteine amino acids in a protein?
Definition
disulfide bond
Term
What is the strongest type of interaction between an isoleucine amino acid and a phenylalanine amino acid?
Definition
london dispersion forces (all carbons)
Term
What is the process of altering the shape of a protein without breaking the amide bonds that form the primary structure?
Definition
denaturation
Term
what is a zymogen
Definition
an inactive form of an enzyme that can be converted to the active form when needed
Term
What is the three-dimensional arragement of localized regions of a protein into α-helices and β-pleated sheets called?
Definition
secondary structure of protein
Term
What are some characteristics of an α-helix?
Definition
  • the N—H and the C=O bonds point along the axis of teh helix in opposite directions
  • there are 3.6 amino acids  in each turn of the helix
  • the C=O group of one amino acid is hydrogen bonded to an N—H group four amino acid residues farther along the chain  
Term
examples of globular proteins
Definition

hemoglobin

myglobin

Term
alpha-keratins
Definition
  • found in hair, hooves, nails skin, and wool
  • nonpolar amino acids exten outwrd from the helix
  • insoluble in water
  • super coil or superhelix
Term
collagen
Definition
  • most abundant protein
  • connective tissues
  • glycine and proline are are large fraction of its amino acid residues
  • left-handed helis
  • right-handed super-helix or triple-helix 
Term
What happens when the pH>isoelectric pH of an amino acid?
Definition

The ammonium cation loses a proton and the amino acid has a net negative charge

(NH3+ becomes NH2)

Term
What is denaturation?
Definition
te process of altering the shape of a protein without breaking the amide bonds that form the primary structure.
Term
What is a co-factor?
Definition
a metal ion or an organic molecule needed for an enzyme-catalyzed reaction to occur.
Term
What is teh role of tRNA?
Definition
  • transfer RNA brings specific amino acids to the ribosomes for protein synthesis
  • is drawn as a cloverleaf shape
Term
What happens during transcription?
Definition
  • is the synthesis of mRNA from DNA
  • DNA splits and the template strand used to make RNA
  • proceeds from the 3' end to the 5' end
  • U replaces T on the mRNA strand
Term
Where are new phosphodiester bonds formed?
Definition
between the 5' -phosphate of the nucleoside triphosphate and the 3' -OH group of the new DNA strand
Term
What is elongation?
Definition
elongation proceeds as the next tRNA molecule delivers the next amino  acid, and a peptide bond forms between teh two amino acids
Term
What is a mutation?
Definition
a change in the nucleotide sequence in a molecule of DNA
Term
What is a point mutation?
Definition
the substitution of one nucleotide for another
Term
What is a deletion mutation?
Definition
when one or more nuclotides is?are lost from a DNA molecule
Term
What is an insertion mutation?
Definition
when one or more nucleotides is/are added to a DNA molecule
Term
What is a silent mutation?
Definition
when the resulting mutation codes for an amino acid that is identical
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