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DNA

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1
What does DNA stand for
Deoxyribonecleic Acid
2
why is DNA important
to code for and interpret the instructions for making proteins neccessary
for life
3
what is dna and rna made up of
nucleotides
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what are th ecomponents of nucleotides
phosphate group, pentose sugar, and nitrogen base
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All of the bonds within the nucleotide are ....
covalently bonded
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What is the location hydrogen bonds in dna
Hydrogen bonds exist between the nitrogen bases in antiparallel strands of the DNA
7
Notice that the sugar is a pentose. what does pentose mean
a sugar with 5 carbons
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Which # carbon attaches to the phosphate molecule?
5'
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Which # carbon atttaches to the nitrogenous base?
1'
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What serves as a connection between 2 nucleotides?
3'
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is dna single or double stranded
double
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dna strands directions are...
anti-parallel
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Adenine always gets paired with
thymine
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Cytosine always get paired with
guanine
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eukkaryotic dna is associated with proteins called
histones
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octamers of histones with coiled dna are called
nucleosomes
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coiled nucleosomes are
chromatin
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coiled chromatin is
chromosomes
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what is the function of nucleosome
help to supercoil the dna to form chromosomes during cell division and help regulate dna expression
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what was the name of the first evidence that DNA were responsible for transmitting genetic info
hershey chase experiment

21
what was the hershey chase experiment also known as
blender experiment
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what radioactive isotope was used to label the DNA in the blender expriment
phosphorus
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what radioactive isotope was used to label the protein in the experiment
sulfur
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why were the viruses / bacteria solution blended in the hershey chase experiement?
to seperate the virus and bacteria -- detach the phage (virus) from the bacterial cells
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which of the two isotope did hershey and chase find in abundance in the bacterial cells (pellet) (this shows what was injected into the bacteria)
phosphorus
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who did the hershey chase experiment?
hershey and chase
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which of the two isotopes did they find in abundance in the supernatent (virus) (this shows what stayed in the virus)
sulfur
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how did hershey and chase's results show that DNA is the genetic material used in living things
it showed that the DNA was injected in to cells to infect them, not the protein
29
two similarities between DNA and RNA
1) nucleotide structure
2) adenine, cytosine, and guanine
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the name of sugar in DNA is
deoxyribose
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What is the sugar in RNA
ribose
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DNA is double stranded, how does this differ in RNA
RNA = single strand
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What base replaces thymine in RNA
uracil
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what does it mean to transcribe something
to put data into a written form
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What is transcription
the process of writing a copy of a gene with a messenger RNA (mRNA) molecule
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Where is the DNA found inside of a eukaryotic cell
Within the nucleus
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if DNA is being used as a template for transciption, where in the cell must transciption occur?
within the nucleus (since DNA cannot leave)
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only 1 enzyme is used during transciption. that is called
RNA polymerase
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what does RNA polymerase do?
1) unwinds DNA double helix

2) adds RNA nucleotides by reading sequence on the template strands
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the strand of DNA used to create the mRNA is called
the templete strand
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why is the templete strand called the antisense strand?
because of the resulting sequence of nitrogen bases in the mRNA
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what does mRNA stand for?
messenger RNA
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what does the antisense strand do?
it has a sequence of nitrogen bases that is the inverse of the sequence of the mRNA
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guanine in DNA gers paired with ___ RNA nucleotide
cytosine
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cytosine in DNA gers paired with ___ RNA nucleotide
guanine
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adenine in DNA gers paired with ___ RNA nucleotide
uracil
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thymine in DNA gers paired with ___ RNA nucleotide
adenine
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RNA polymerase can only add in which direction
5' to 3'
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since transcription is only working on a small segment of DNA (a single gene), RNA polymerase needs to know when to START and END transcription. What parts of the genes helps start / end the transciption
promoter region and termination region
50
what is the promoter region
region upstream of a gene with regulatory elements that signal enxyme binding; this region is the chemical signal for a gene that needs to be transcibed
51
what is the termination region
region of DNA with chemical signals for transciption to end; detachment of enzyme and mRNA molecule
52
what happens when splicing the pre-mRNA
removes sections of the mRNA that do not contribute to the formation of the polypeptide
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what are removed during the splicing of mRNA?
introns
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what are kept during splicing the mRNA?
exons
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what are introns
non coding regions of the mRNA
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what are exons
coding regions of mRNA
57
5' methyl (CH3) CAP is added to the 5' end. What does this do?
this allows for the mRNA to be protected from exonucleaes and to make it recognizbale to the nuclear membrane transport proteins and ribosome for translation
58
poly AAA tail is added to the 3' end, what does this do?
this improves the stability of the mRNA and aids in its transports out of the nucleus
59
what is another words for a collection of genes
genome
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what are codons
the mRNA molecule contains a specific sequence of bases are read in segments of 3
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one codon =
one amino acid
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what doe the stop codons do
signal the end of transaltion
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what is the first step of translation
initiation
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what happens during initiation in translation?
the mRNA ribosome, and first tRNA complex will bind to begin the process of creating the polypeptide. The small subunit of the ribosome binds first, follow by the large subunit and tRNA
65
ribosomes consist of 2 subunits. does the mRNA attack the small or the large subunit of the ribosome first?
small
66
the first tRNA carries the amino acid methionine. on the other end of the tRNA, a 3 base sequence called the anti-codon binds to the codon. Explain how this binding is possible.
This is possible through complementary base pairing (A with U and C with G)
67

what does tRNA stands for
transfer RNA
68
explain why mRNA and tRNA are appropriate names for the function of these 2 molecules
mRNA brings the "message" of the instructions for a polypeptide form the DNA in the nucleus to the ribosome for translation. tRNA transfers the amino acid to the ribosome where it an be adfed to the polypeptide chain
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notice how there are 3 tRNA binding sites in the ribosome: the E or exite site, P or peptidyl site, and A or aminoacyl site. To which site does the first tRNA bind during initiation
P site
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What is the step 2 in translation
elongation
71
what happens during elongation
the ribosomes slides along the mRNa molecule and tRNA molecules carrying amino acids will attach following the base pairing rules. As a tRNA entrers the A sitre, the tRNA at the P site will attack its amino acid with a peptide bond, then slide along to the E site where it can exit. this continues until a stop codon is reached
72
during elongation, how many tRNA molecules are held in the ribosome at the same time?
2
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what is the name of the bond that forms between 2 amino acids side by side in the ribosome
peptide bond
74
the P site always holds the growing polypeptide chain. Describe how the translocation of the ribosome to the next codon allows for the NExt tRNA to enter the ribosome
as the ribosome slides along the molecule of mRNA, the tRNA in the P site shifts to the E site and the tRNA in the A site shifs to the P site. The tRNA in the E site can now exit and another tRNA can bind to the A site
75
what happens at the E site
the "empty" tRNA exits the ribosome
76
what happens at the A site
a tRNA carrying an amino acid that corresponds with the codon at the a site binds
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what is p site
peptidyl site
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what is E site
exit site
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what is A site
aminoacyl site
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The codon UUU corresponds to which anticodon?
AAA
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Which amino acid corresponded to the codon UUU
Phenylalnine
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Which code is on the genetic code "wheel"
mRNA codons
83
what is step 3 in translation
termination
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what happens during termination in translation
when a stop codon is reached, a release factor will ind signaling to take ribosome to detach. The polypeptide chain created can then be used to create a protein and the mRNA will be destroyed by the cell
85
describe two things. when a stop codon is reached during termination
small and large ribosomal subunit detach, polypeptide detaches
86
the free polypeptide is only the prrimary structure of a protein. breifly describe what will change about the polypeptide in order to become a functional protein
folding and twisting to make a 3D shape and potentially binding to another polypeptide to make a quaternary structure
87
what molecule provides the energy to activiate the amino acid so it can bind to its matching tRNA
ATP
88
how is the energy release from this molecule different than what we saw earlier this year?
two phosphate groups are removed to form AMP (adenosine monophosphate)
89
whay are there 20 different tRNA acitvating enzymes?
there are 20 different amino acids and enzymes are specific to their substrate
90
what is the difference between prokaryotic and eukaryotic cells in terms of where their DNA is located
in eukaryotic cells DNA is located in the nucleus. prokaryotic cells do not have a nucleus so DNA is free-floating.
91
how does the DNA being located in the nucleus change the timing of transcription and translation?
these processes are faster in prokaryotic cells because they can happen simultaneously
92
what are free ribosome?
proteins that are used in the cytoplasm, mito, or chloroplasts are typicaly made by ribosomes that are free ribosomes
93
what are bound ribosomes
proteins that are packaged into lysosomes or are to be delievered outside of the cell are produced by bound ribosomes on the rough ER
94
to which organelle do proteins made by the rough ER often travel for further modification and packaging
golgi
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what type of transport is seen to deliver proteins out of the cell
exocytosis
96
what organelle could be made that contains digestive enzymes made by bound ribosomes
lysosomes
97
how cna you form a polysome
multiple ribosomes can be attached to a single mRNA molecule at once
98
addition of methyl groups to the histone proteins makes the nuclesomes twist tightly together. when nucleosomes aer more tighly owund, how is the expresion of genes impacted? why?
expression of these genes is turned off -- the tighter the region of DNA is wound, the less likely RNA polymerase is to access that region to transcribe it
99
addition of acetyle groups to histone proteins makes the nucleosomes more loosely wound. when the nucleosomes are less packed together, how is the expression of genes impacted? why?
expression of these genes is turned on -- less tightly wound DNA means that RNA polymerase can more easily access these sequences for transcription
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