BIO CH 12&13

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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


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