BIO CH 12&13
a ribosome has 1 binding site for mRNA and 2 binding sites for tRNAs
F; 3 binding sites for tRNA
an RNA primer is synthesized by RNA primase
F; DNA primase
the template DNA strand is described as being parallel to the complementary RNA strand
F; antiparallel
the two strands of a dna double helix can be described as running parallel to each other
F; antiparallel
okazaki fragments are found in the leading strand of DNA
F; lagging strand
one of the pyrimidine bases in a DNA molecule is adenine
F; purine
the process of DNA replication is conservative
F; semiconservative
uracil forms a complementary pair with ___ in RNA and ____ in DNA
adenine;adenine
During protein synthesis, ribosomes
attach to the mRNA molecule and travel along its length to produce a polypeptide
who discovered that DNA was responsible for bacterial transformation
avery
give names of 3 enzymes involved in nucleotide excision repair
helicase- breaks open DNA DNA polymerase- replaces missing DNA DNA ligase- seals gap in backbone of strand
who discovered that the genetic material in bacteriophages is DNA
hershey and chase
who used proteins labeled 35S and DNA labeled with 32P to demonstrate that viral DNA entered bacterial cells, but viral proteins did not
hershey and chase
initiation of transcription requires
promoter sequence
prevents the hydrolysis of single dna strands by nucleases
single strand binding protein
prevents formation of H bonds between complementary base pairs
single strand binding proteins
RNA is _____ and contains the nitrogenous base ______, which is absent in DNA
single-stranded; uracil
the wobble hypothesis states that
some amino acids are coded for by more than one codon
which of the following statements concerning DNA is FALSE?
sugar present in DNA is ribose
The ends of eukaryotic chromosomes can be lengthened by:
telomerase; adds repetitive nucleotide sequences
______, the ends of eukaryotic chromosomes, shorten with every cell division
telomeres
completed polypeptide chain released from ribosome
termination
triggered by a stop codon
termination
the total number of different 3 base combinations of the 4 nucleic acid bases is
64
what joins successive nucleotides to a growing polynucleotide strand, complementary to the template strand
polymerase
which base connects to which and how many H bonds are between them
DNA: A+T 2 H-bonds G+C 3 H-bonds
the chemical group in box 5 of the accompanying figure is a
phosphate
list the main steps involved in converting pre-mRNA to mRNA
1. addition of 5' cap: allows ribosomes binding to mRNA & may protect mRNA transcripts from degradation 2. addition of a poly-A tail: aids in export of the mRNA transcript from nucleus; allows ribosomes to recognize mRNA for translation 3. removal of introns: removes noncoding sequence 4. splicing of exons: joins consecutive coding regions after the removal of intervening introns
before the 1940's scientists believed that proteins, rather than DNA, were the carriers of genetic material into the cell. Why?
20 different amino acids could produce a large number of unique combinations
in the accompanying figure, the portion of the molecule containing the anticodon is indicated by the label
3
which of the following nucleotide sequences represents the complement to the DNA strand 5'-AGATCCG-3'?
3'- TCTAGGC- 5'
one of the mRNA codons specifying the amino acid leucine is 5'-CUA-3'. Its corresponding anticodon is:
3'-GAU-5'
translation is initiated at the _____
AUG codon
name 4 nitrogenous bases
Adenine, Thymine, Cytosine, Guanine (DNA) adenine, uracil, cytosine, and guanine (RNA)
introns in pre-mRNA
Are spliced out of the message
Compare and contrast DNA and RNA
Both are nucleic acids and house information crucial to the cell. However, they are very different. DNA is a doubles stranded helix with deoxyribose for its sugar. It has the base thymine. RNA is single stranded and has uracil in place of thymine. Its sugar is ribose. ON PAPER
which of the following causes the unwinding of the DNA double helix
DNA helicase
okazaki fragments are joined together by
DNA ligase
adds nucleotides only to the 3' end of an existing polynucleotide strand
DNA polymerase
when a mutation occurs during DNA replication, ____ replaces the incorrect nucleotide with the correct one after the mismatched nucleotide has been removed
DNA polymerase
which of the following adds new nucleotides to a growing DNA chain
DNA polymerase
what is the modern definition of a gene
DNA sequence that encodes a specific RNA or protein product
the bacteriophages used by Hershey and Chase showed that:
DNA was injected into the bacteria and protein was left on the outside
a grouping of 3 nucleotides code for one amino acid
T
adenine and thymine are held together by 2 H bonds in a double stranded DNA molecule
T
how are eukaryotic chromosomes replicated
The linear DNA molecules are replicated from multiple origins of replication bidirectionally.
a replication fork is
a y-shaped region where parental DNA strands are separated by helicase
Why is only one strand of DNA transcribed into mRNA?
because transcribing both DNA strands would produce different amino acid sequences
who demonstrated the ratio of nucleotide bases in DNA
chargaff
what allows each strand of dna to serve as a template for a new DNA strand during replication?
complementary base pairing between purines and pyrimidines on opposite strands
_____ bonds link the sugar and phosphate groups in the backbones of DNA molceules
covalent phosphodiester
hydrogen bonds can form between guanine and _____, and between adenine and _____
cytosine; thymine
what catalyzes formation of sugar phosphate bonds in adjacent okazaki fragments
dna ligase
what conclusions did Beadle and Tatum reach in their studies of Neurospora
each mutant gene affected only one enzyme
growth of the polypeptide chain
elongation
protein synthesis proceeding in a 5' to 3' direction
elongation
x-ray diffraction images produced by _____ were used by watson and crick to infer the structure of DNA
franklin
who demonstrated that genetic traits can be transferred from one bacterium to another
griffith
binds DNA at the origin of replication and breaks the H bonds between paired bases
helicase
opens the double helix like a zipper
helicase
what catalyzes the synthesis of an RNA primer at both leading and lagging strand
helicase
assembly of the ribosome
initiation
first stage of translation
initiation
initiator tRNA binds to the start codon
initiation
frameshift mutations result from the
insertion or deletion of 1 or 2 base pairs
in DNA replication, the lagging strand
is synthesized as a series of Okazaki fragments
which of the following is a characteristic of uracil
it has the ability to bond with adenine
why is DNA able to store large amounts of information?
its nucleotides can be arranged in a large number of possible sequences
the DNA strand that is replicated smoothly and continuously is called
leading strand
catalyzes a reaction that occurs in the lagging strand but not in the leading strand
ligase
which of the following is made from DNA
mRNA, tRNA, rRNA
who demonstrated that DNA is replicated semi-conservatively
meselson & stahl
who gre bacteria in the presence of heavy nitrogen (15n) followed by growth 14N medium for one or two generations, then measured the density of the DNA
meselson & stahl
Garrod first proposed that
metabolic defects were due to the lack of an enzyme
a mutation that replaces one amino acid in a protein with another is called a ______ mutation
missense
mobile genetic elements, such as transposons and retrotransposons, are significant because
mutations are caused by retrotransposons contribute greatly to a species' evolution
a _____ mutation results in the conversion of a codon specifying an amino acid to a termination codon
nonsense
what type of subunits make up a single strand of DNA? what do they contain? how are the subunits linked?
nucleotides consisting of a sugar (ribose in RNA and deoxyribose in DNA) attached to a phosphate group & a nitrogenous base linked together by covalent H bonds between phosphate group of a nucleotide & 3rd carbon of pentose sugar producing backbone
Because a newly synthesized DNA molecule contains ____, the replication process is said to be semiconservative
one parental strand and one new strand
How is the 4-letter language of nucleic acids converted into the 20-word language of amino acids?
the 4 nucleic acid bases combine in 3 letter sequences that define different amino acids
according to Chargaff's rules:
the adenine content in any DNA molecule is always equal to the thymine content
the portion of the molecule labeled as 5 is
the attached amino acid
how is a bacterial chromosome replicated
the circular DNA molecule is replicated from one origin of replication bidirectionally
from the DNA x-ray crystallography data, franklin and wilkins inferred that _____ while watson and crick determined that
the flat nucleotide bases are stacked on top of each other; DNA is helical
which of the following statements is false with regard to dna replication
the strand being copied is read in the 5' --> 3' direction (its not)
linus pauling demonstrated that
the structure of hemoglobin was altered by a mutation of a single gene
errors in DNA replication can come from
the suns UV radiation
what produces breaks in the dna molceules and then rejoins the strands to prevent supercoiling
topoisomerate
RNA synthesis is also known as
transcription
in the experiments of Griffith, the conversion of nonlethal R-strain bacteria to lethal S-strain bacteria:
was due to transformation
