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46 Cards in this Set

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Where are nucleic acids located in prokaryotes?
cytosol
Where are nucleic acids located in eukaryotes?
mainly in the nucleus, some in the mitochondria and ribosomes
What are 4 functions of nucleic acids?
1) Storage and transfer of genetic info (DNA, RNA, mRNA)
2) Regulation of protein expression (RNA siRNA)
3) Protein synthesis (tRNA, rRNA)
4) Catalytic functions (ribozymes)
How many rings does a purine have? Pyrimidine?
2, 1
Which nitrogenous bases are purines?
Adenine, Guanine
Which bases are pyrimidines?
Cytosine and Thymine (or Uracil in rna)
Which base can methylated in DNA? RNA?
Cytosine, all of them
if Cytosine becomes methylated, it then becomes also known as
Thymine
MEMORIZE STRUCTURES OF ALL BASES
DO IT
What are some of the functions of methylated bases?
1) protect your DNA from bad DNA
2) error correction
3) protection from nucleases
There is one uncommon base that is used especially in tRNA. What is it's name(s)
Inosine aka hypoxanthine
What is a nucleoside?
a nitrogenous based attached to a sugar
if adenine is attached to a sugar with an H on carbon 2, what would it be called?
Deoxyadenosine
if cystosine was attached to a sugar with an OH on carbon 2, what would it be called?
Cytidine
How do you name a nucleoside?
1)Identifying what element is on Carbon 2 (H is DNA, OH is RNA)
2) Add deoxy if it for DNA
3) If it is a pyrimidine, it will end with 'idine"
If it is a purine, it will send with 'osine'
What is a nucleotide?
A nucleoside attached to a phosphate backbone
an example of an important nucleotide that is involved in cellular energy would be
ATP (adenosine triposphate)
How are nucleotides bound together?
Phosphodiester bonds
DNA and RNA start at which end (5' or 3')
5'
Why is it called the 5' end?
The phosphate is connected to carbon 5 on the initial nucleotide
Why is it called the 3' end?
the last phosphodiester bond (hydroxyl) on the last nucleotide is connected to Carbon 3
1) what base pairs with A?
2) what base pairs with G?
1) T or U (in RNA)
2) C
What is a wobble pair?
When two bases bond that aren't normally paired together
What is the predominant conformation for DNA?
B-form (right-handed)
What is the predominant conformation for RNA?
A-form (left-handed)
Besides B form, DNA can also take on this conformation.
Z form (left handed)
B form of DNA is typical under what conditions?
normal physiological conditions
A Z-form of DNA would occur under what conditions?
when alternating purine and pyrimidine sequences exist.
What implied role does the purine-pyrimidine Z form of DNA have?
A possible role in gene regulation
Is RNA single stranded or double stranded?
single
how would a single stranded RNA create loops?
Some of the bases are compliments...therefore they would pair up to form a helix. When bases can't pair up, then form loops or bulges
What is supercoiling?
Further twists on the double helix
What enyzyme introduces negative supercoiling?
DNA gyrase
Negative supercoils go clockwise or counterclockwise?
counterclockwise
Positive supercoils to clockwise or counterclockwise?
clockwise
What role does a topoisomerase play in supercoiling?
To reduce supercoiling
What is a Class I topoisomerase?
it cuts the backbone of the supercoiled strand and passes and other strand through
What is a class II topoisomerase?
it cuts both backbones and passes through another part of DNA
how many possible start points do prokaryotic DNA have?
1, becuase it is circular,
is DNA circular?
no, linear
How is DNA packaged?
It is packaged by forming nucleosomes, which are 146 bases pairs of DNA wrapped about a histone protein
Protein/DNA material is called ____
chromatin
A single chromosome fiber is called a
chromatid
Why does DNA store genetic information and RNA does not?
There is spontaneous breakdown and mutations of RNA, short half life (4 years as oppose to DNA's 100000 years)
What are endonucleases?
they hydrolize (cleave) phosphodiester bonds that are in the middle of a nucleic acid
What are Exonucleases?
They cleave phosphodiester bonds from free ends of nucleic acids