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Biochem mid term 2
content from end of first mid term to second midterm
76
Biochemistry
Undergraduate 2
11/02/2010

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Term
where does Translation occure?
Definition
on ribosomes
Term
what does tRNA do?
Definition
reads mRNA and brings appropriate amino acids.
Term
tRNA carries amino acids on what end? and what is on the opposite end?
Definition
3' end and a anticodon loop
Term
are all ribosomes protiens?
Definition
no some are enzymes
Term
what is a anticodon loop?
Definition
anitcodon loops have specific bases on the RNA telling wich Amino acid is needed.
Term
True or false the genetic code is the same for every living organism?
Definition
True
Term
what is a Iso acceptor tRNA?
Definition
has a different anticodon loop but same amino acid.
Term
how many codons are there?
Definition
64
Term
AUG represents what?
Definition
represents the translation start and also codes for methionine.
Term
the start codon defines what?
Definition
reading frame
Term
what happens in a mutation?
Definition
DNA is relativly stable but base sequences can be altered under certain circumstances. mistakes occur during replication. chemical mutagens and ionizing radiation can cause insertions/deletions of bases.
Term
what is a Non-sense mutation?
Definition
codon is changed to come to a premature stop
Term
What is a frame shift mutation?
Definition
nucleotide is added or deleted
Term
what is a mis-sense mutation?
Definition
codon is changed representing a different amino acid
Term
what is a Silent mutation?
Definition
a codon is changed but codes the same amino acid.
Term
who coined the term "protiens"
Definition
J.Berzelius
Term
what is the literal meaning of "Protien"?
Definition
of first rank or very important
Term
protiens can spontaneusly fold into what?
Definition
3D structures
Term
virtually all enzymes are ____________?
Definition
proteins
Term
enzymes catalyze all biochemical reactions by increasing ___________?
Definition
rates of reactions
Term
proteins can ________ small molecules like oxygen and iron.
Definition
transport
Term
name the seven functions of Protiens.
Definition
enzymatic Catalysis
Transport and Storage
Coordinated motion
Mechanical strength
Immunity
Neurotransmission
Growth and differentiation
Term
What is the centeral Dogma?
Definition
DNA---RNA---Protein
Term
can one amino acid sequence have two structures?
Definition
no
Term
What is pKa?
Definition
is the pH at which 50% ofan ionizable group is ionized
Term
what happens at pH values > pKa?
Definition
removal of a proton
Term
What happens at pH values < pKa?
Definition
addition of protons occurs
Term
what is a Zwitterionic form?
Definition
when 50% of the ionizable groups become ionized. pH is 7.
Term
Name all the amino acids that are Hydrophobic.
Definition
Alanine
Valine
Phenylalanine
Tryptophan
Leucine
Isoleucine
methionine
proline
Term
Name all the polar amino acids.
Definition
Serine
Threonine
Tyrosine
Cysteine
Asparagine
Glutamine
Histidine
Glycine
Term
Name all the charged amino acids
Definition
Aspartate
Glutamate
Lysine
Arginine
Term
is Histidine an acid or a base?
Definition
Histidine can act as an acid or a base.
Term
Cysteine can interact and creat what kind of bonds?
Definition
Disulfide bonds
Term
a peptide bond forms where?
Definition
Between a C=O and a N. peptide bonds have a biproduct of a water molecule.
Term
does peptide bonds exist primarily in Trans or Cis formation?
Definition
Trans
Term
are Proline peptide bonds Cis or Trans?
Definition
can be either or
Term
why is there a restricted freedom between bond angles?
Definition
steric exclusion is a powerful organizing principle
Term
what is the Ramachandran plot?
Definition
it shows at what Phi/Psi angles are possible.
Term
what are the four levels of protein structure?
Definition
Primary structure- sequence of amino acids
Secondary structure- locally organized regions
Tertiary structure- 3D shape
Quaternary structure-multiple units of the same protein coming together.
Term
what is the primary structure?
Definition
the linear sequence of amino acids that constitutes a polypeptide/protien
Term
what is the direction of the primary structure?
Definition
N---C
Term
protein conformation is dictated by what?
Definition
the nature of the side chains. peptide bonds are rigid
Term
the secondary structure of protein is?
Definition
the folding of polypeptide/protein chains into regular structures like alpha helixes and beta sheets as well as turns and loops.
Term
the Alpha helix in a protien structure is left or right handed?
Definition
right handed
Term
an alpha helix has how many amino acids per turn?
Definition
3.6
Term
true or false side chains extend inward toward the helical axis?
Definition
False side chains extend outward away from the helical axis.
Term
can the side chains of one alpha helix interact with those of another?
Definition
yes
Term
what is it called when one whole side of a alpha helix is polar and the other side is nonpolar?
Definition
amphiphilic
Term
what is a superhelix?
Definition
when two helixes are wound around each other. they are very strong and are mostly found in the musculoskeletal system.
Term
who discovered beta sheets?
Definition
pauling and Corey
Term
what kind of bonds are between adjacent strands of a beta sheet?
Definition
hydrogen bonds
Term
beta sheets can run in a _______ direction or a _________ direction.
Definition
parallel and antiparallel
Term
one amino acid is attached to __ hydrogens.
Definition
2
Term
what are the function of turns and loops?
Definition
for the reversal of polypeptide chain direction
anitgen-binding sites of antibodies are made up of loops
hypervariability of loops are important for immunity
Term
where are polar amino acids located on a protein?
Definition
on the surface
Term
where are hydrophobic AA located in a protein?
Definition
inside
Term
can hydrogen bonds happen on side chains?
Definition
yes
Term
degrading proteins
Definition
making a protein smaller
Term
denaturing a protein
Definition
destroying a protein
Term
a protein core must be _______ charged.
Definition
nuturally
Term
What is a multimeric protein?
Definition
more then one fully folded protein
Term
what is a homodimer?
Definition
same/identical protein sequence and structure
Term
what is a heterodimer?
Definition
has different subunits
Term
hemoglobin has __% carrying capacity of oxygen and Myoglobin has __%
Definition
90% and 7%
Term
how many subuntis does hemoglobin and myoglobin have respectivly?
Definition
4 untis and 1 unit
Term
what is the main reason for the difference in oxygen carrying capacity of hemoglobin and myoglobin?
Definition
binding in hemoglobin has four polypeptide chains and binding of oxygen is cooperative.
Term
what is the prostetic group?
Definition
tightly bound to the protein and helps in the functioning of the protein group.
Term
is there a higher amount of alpha helix's in myoglobin or hemoglobin?
Definition
myoglobin
Term
what is the structure of heme?
Definition
Fe-4N
Term
what is Anemia?
Definition
lack of Iron
Term
heme is always attachted to two ______.
Definition
histadine
Term
can you change the environment around the heme molecule?
Definition
no because it can destroy its functioning
Term
heme is the binding site for what?
Definition
oxygen
Term
hemoglobin transports oxygen by?
Definition
cooperative binding
Term
what does the sigmoital curve represent?
Definition
cooperativity
Term
does oxygen binding of one chain influence the binding on another chain?
Definition
yes
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