Exam 2 – Chemistry Answers – Flashcards

Unlock all answers in this set

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

the helix

the pleated sheet

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

hydrogen bonds

ionic attractions

hydrophobic interactions

disulfide bridges

question
What is true about denaturation?
answer
  • 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
question
What are the characteristics of enzymes?
answer
  • 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
question
Describe lock-and-key model of an enzyme.
answer
  • enzyme atcive site has a rigid structure complementary to that of the substrate 
question
describe the induced-fit model of an enzyme.
answer
enzyme conformation changes when it binds the substrate so the active site fits the substrate
question
what happens to an amino acid at pH<isoelctric pH (pI)?
answer

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

 

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

 

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

P—O—C

 

question
what is a phosphoanhydride bond?
answer
P—O—P
question
What is a phosphoanhydride bond?
answer
P—O—P
question
Replication
answer
  • both DNA strands are duplicated
  • semi-conservative
  • uses DNA polymerase
question
transcription
answer
single DNA strand is used to produce mRNA
question
translation
answer
  • amino acids added to peptide chain
  • requires tRNA
  • ribosomes 
  • RNA to protien
question
In which dirction does replication occur?
answer
3' end to the;5' end
question
tRNA
answer
  • anticodon
  • smallest RNA molecule
  • transports amino acids 
question
mRNA
answer
  • 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
question
rRNA
answer
combines with protein to form ribosomes
question

Describe silent mutation and give examples

answer
  • 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 
question
Describe a missense mutation and give examples.
answer
  • 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 
question
describe a nonsense mutation and give examples
answer
  • the new codon is a stop codon
    • subtitution of UGA for a codon
    • a person makes a truncated, nonfunctional protein 
question

Name the basic amino acids

 

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

hemoglobin

myglobin

question
alpha-keratins
answer
  • found in hair, hooves, nails skin, and wool
  • nonpolar amino acids exten outwrd from the helix
  • insoluble in water
  • super coil or superhelix
question
collagen
answer
  • 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 
question
What happens when the pH>isoelectric pH of an amino acid?
answer

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

(NH3+ becomes NH2)

question
What is denaturation?
answer
te process of altering the shape of a protein without breaking the amide bonds that form the primary structure.
question
What is a co-factor?
answer
a metal ion or an organic molecule needed for an enzyme-catalyzed reaction to occur.
question
What is teh role of tRNA?
answer
  • transfer RNA brings specific amino acids to the ribosomes for protein synthesis
  • is drawn as a cloverleaf shape
question
What happens during transcription?
answer
  • 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
question
Where are new phosphodiester bonds formed?
answer
between the 5' -phosphate of the nucleoside triphosphate and the 3' -OH group of the new DNA strand
question
What is elongation?
answer
elongation proceeds as the next tRNA molecule delivers the next amino  acid, and a peptide bond forms between teh two amino acids
question
What is a mutation?
answer
a change in the nucleotide sequence in a molecule of DNA
question
What is a point mutation?
answer
the substitution of one nucleotide for another
question
What is a deletion mutation?
answer
when one or more nuclotides is?are lost from a DNA molecule
question
What is an insertion mutation?
answer
when one or more nucleotides is/are added to a DNA molecule
question
What is a silent mutation?
answer
when the resulting mutation codes for an amino acid that is identical
Get an explanation on any task
Get unstuck with the help of our AI assistant in seconds
New