Term
DNA as genetic material. DNA was first extracted from nuclei in _____ and
named ‘_____’ after their source.
• Chemical analysis determined that DNA was a _____ rich in _________. |
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Definition
1870, nuclein
weak acid, phosphrous |
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Term
DNA stands for:
_________: it contains a ______
it is weakly ______, and is
found in the _______.
• Because of its nuclear localization and subsequent
identification as a component of chromosomes.... |
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Definition
deoxyribose nucleic acid, sugar, acidic,nucleus.
-it
was implicated as a carrier of genetic information. |
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Term
• Chromosomes are also known to contain protein,
so early on it was a challenge to demonstrate that
DNA was indeed the molecule that contained the
genetic information.
• Because proteins are built of 20 building blocks
(amino acids) whereas DNA only 4 (nucleic acids)
scientists reasoned that the vast extent of
hereditary information had to be located within
...
• Classical experimental data confirmed DNA as the
genetic material. |
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Definition
| ...proteins (greater potential for diversity). |
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Term
Griffiths Experiment- published in 1928 demonstrated....
Bacteria contained a single circular chromosome... |
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Definition
...bacterial transformation from rough to smooth strain.
...they are haploid. |
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Term
Griffiths bacterial observations
In one strain, streptococcous pneumoniae, two variants
are seen...
• The S form has a _______ capsule covering it,
causing it to appear _____. |
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Definition
... the S and the R forms, with smooth or rough surfaces.
-polysaccharide, smooth. |
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Term
Bacterial Coats
The smooth coat also protects
the bacteria...
• The rough variant ... |
|
Definition
...from being killed by an animal’s immune
system.
...lacks the coat, and is therefore
destroyed by the infected animal’s immune system. |
|
|
Term
Griffith observed that live S bacteria...
• When he heat killed the S variants and mixed them with live R
variants, and then injected the mixture in the mice...
• Griffith was able to isolate the bacteria from the dead mice....
• Thus the bacteria had been Transformed... |
|
Definition
...could kill mice injected with them.
...they died
..., and
found them to be of the S variety
... from the rough to the
smooth version. |
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Term
• The ability of a substance to change the genetic characteristics
of an organism is known as _____.
• Scientists set out to isolate this ‘_____’ since
they were convinced it was the carrier of the________ . |
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Definition
-transformation
-transforming principle
-genetic information
information |
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Term
| Hershey-Chase experiment used what? What year? |
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Definition
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Term
Hershey- chase
The phage are made up of equal parts of ____ and ____.
• It was known that the phage infected by anchoring the _____ _____to
the cell surface and then ....to the cell,
infecting it |
|
Definition
-protein, DNA
-outershell
-deposits the inner components |
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Term
For the Hershey-Chase phage experiment Scientists were interested in finding out whether it was the ____
component or the ____ component that got deposited inside the
infected cell.
• By incorporating _____ either in the protein or the DNA of
the infecting phage, they determined that the ___ was indeed
introduced into the infected bacteria, causing ______ of new___ |
|
Definition
-protein, DNA
-radiolabel, DNA
-poliferation, phage. |
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Term
| The basic components of DNA |
|
Definition
| Deoxyribose, and a phosphaste group. |
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Term
|
Definition
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Term
|
Definition
|
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Term
DNA is _____: 5’ to 3’
_________ bond connects the
sugar to the nitrogen base.
A ________ bond connects one
nucleotide to the next.
The ______ _______ ______is
identical in every DNA molecule.
In any DNA purine ___ pyrimidine |
|
Definition
-polar
-Beta N-glycosidic
-phosophodiester
-sugar phosphate backbone
-equal to |
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Term
Watson-Crick Model..
_____ _______ structure
the two strands are ________
-It is a right handed helix, the structure is called ___ _____ |
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Definition
-double helical
-anti-paralell
-B DNA |
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Term
Watson- Crick Model
Complemetary Base pairing- ___ hydrogen bonds between C and G and __ bonds between A and T |
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Definition
|
|
Term
B- DNA have ___ base pairs per ___ turn
There is a ____ and a ____groove per turn.
Successive base pairs are
stacked on top of each other
at a rotation of ___°, and
adjacent bases interact each
other to _____ the helix. |
|
Definition
-10, helical
-major, minor
-36, stabilize |
|
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Term
RNA
_____ sugar instead of deoxyribose
• ______ instead of thymine as one pyrimidine.
This base can complementary base pair with ______.
• Single stranded molecule... |
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Definition
Ribose
Uracil
Adenine
....normally does not form double helical structure |
|
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Term
RNA
• Folding causes it to base pair with ...
• Multiple types of RNA exist: |
|
Definition
-complementary
segments of same molecule
-messenger RNA,
transfer RNA, ribosomal RNA etc. |
|
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Term
RNA is assembled into the separate entities:
they assemble... |
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Definition
-The sugar (ribose) a phosphate group, the 4 bases.
-into a ribonucleotide
-the ribonucleotide assembles to form a single strand of ribonucletide. |
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Term
DNA replication
A process by which genetic information is copied for...
• Begins with the unwinding of the double helix to
expose ... |
|
Definition
...transmission to the next generation of cells.
...the bases in each strand of DNA |
|
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Term
DNA Replication
• Each unpaired nucleotide will attract a ____ _____from the medium, which will form base
pairing via ________.
• Enzymes link the aligned nucleotides by ______ _____ to form a continuous strand. |
|
Definition
-complementary nucleotide, Hydrogen bonding
-phosophodiester bonds. |
|
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Term
| Semiconservative replication |
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Definition
Two strands, one old and one newly synthesized, are
paired up: |
|
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Term
|
Definition
both newly synthesized
strands form the new daughter molecule,
with parental molecule remaining intact. |
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Term
|
Definition
fragmentation of daughter and
parental molecules causes both molecules to
be interspersed with new and old DNA. |
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Term
Meselson-Stahl Experiment proved ____ ______ Model of Replication
• Experiment allowed differentiation of _____ ______ |
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Definition
| Semi conservative, parental and newly formed DNA. |
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Term
Meleson- stahl experiment
• Bacteria were grown in media containing either
______ ______.
• DNA banded after equilibrium density gradient
centrifugation at a position which matched the
density of the DNA: |
|
Definition
-Normal isotope of nitrogen- 14, or a heavy isotope- 15.
-heavy DNA was at a higher
density than normal DNA. |
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Term
Meleson-Stahl experiment
When bacteria grown in 15N were
transferred to normal 14N containing
medium, the newly synthesized DNA strand
had the ___ while the parental strand had___.
• They checked the composition of the
resulting DNA molecules by _____ ____ ___, and found an
intermediate band, indicating a ... |
|
Definition
14N, 15N
-density
gradient centrifugation
...hybrid
molecule containing both 14N and 15N DNA. |
|
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Term
| DNA Replication is a tightly controlled process.... |
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Definition
| occuring at specific times during the cell cycle. |
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Term
DNA replication
Requires a set of _____ and _____, and
requires energy in the form of ____. |
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Definition
|
|
Term
Two basic steps in DNA replication
Two basic componenets |
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Definition
Initiation and Elongation
template and primer. |
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Term
_____ ____ is the enzyme that extends the
primer; additional enzymes/proteins... |
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Definition
DNA Polymerase
i)unwind
DNA (helicase) , ii)bind to single stranded DNA
to keep the helix open (single strand DNA binding
proteins) and iii) make the RNA primers
(primase). |
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Term
DNA replication at the molecular level-
Replication is _______.
• For circular DNA, the unwinding at the replication
forks causes ______. |
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Definition
Bidirectional.
Supercoiling |
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Term
• DNA topoisomerases are enzymes that ...
• The ends of chromosomes (telomeres) cannot be
replicated on the lagging strand because ... |
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Definition
...help relax the
DNA by nicking the strands, releasing the twists and
then rejoining the DNA ends.
...there is no
primer available |
|
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Term
• Telomerases are enzymes that contain _______
which extend the ends of chromosomes, ensuring that
the chromosome ends are not ______ _____
with each replication. |
|
Definition
-RNA primers
-progressively shortened |
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Term
Accuracy in replication is essential for
proper transmission of genetic information.
• A small error in replication can lead to a
potentially ... |
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Definition
| ...lethal mutation or disorder. |
|
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Term
| • Accuracy is achieved by: |
|
Definition
– Redundancy
– Proof-reading
– Repair |
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Term
Homologs physically break, exchange parts and rejoin.
• The breakage and repair creates ... |
|
Definition
...reciprocal products of
recombination |
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Term
Heteroduplex formation:
• Recombination can occur anywhere along the DNA molecule. |
|
Definition
the two strands of DNA may not break at
precisely the same point, it may be a bit staggered, resulting in a
portion of the DNA where each strand comes from a different
origin: heteroduplex. |
|
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Term
|
Definition
| there is no gain or loss of nucleotides |
|
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Term
|
Definition
when recombination occurs within a gene such
that each strand of the resulting heteroduplex does not have
complementary bases and conveys a different message, one of the
strands has to be converted so that the two strands convey the same
message. |
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Term
| Heteroduplex region of chromosome. |
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Definition
| where two strands switch places. May occur on recombinant or nonrecombinant molecules. |
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Term
|
Definition
| mismatched heteroduplex correction, you end up with a unexpected arragement of alleles. |
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Term
Cracking the genetic code
Discovery of ____ as an intermediate molecule helped crack the genetic code.
Scientists developed cell extracts which when mixed with mRNA, could synthesize ________chains: _____ translation. |
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Definition
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Term
Scientists were also able to synthesize short segments of mRNA of _____
scientists began cracking the genetic code in a systematic fashion: UUUUUU--- = Phe-Phe---, UCUCUC--- = Ser-Leu---- , etc.
•Some ambiguities were resolved by further experimentation |
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Definition
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Term
|
Definition
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Term
| Poly U-experiment- set up an invitro translation system plus ____ ____ __, then analyze the ____ ______ synthesized. |
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Definition
radioactive amino acids.
Radioactive polypeptides |
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Term
| By 1965 it was known that polypeptide chains were synthesized on _____, and that different ____molecules carry the appropriate _____ to the ribosome depending on the genetic _____ on the mRNA. |
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Definition
| ribosomes, tRNA, amino acid, codon |
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Term
| Using ______amino acids, and defined mRNA sequences, it was determined which ____corresponded to which ______. |
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Definition
| radiolabeled, codon, amino acid. |
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