Chapter 3 Review Flashcards
DNA is a polymer of
dNMPs
Pyrimidines include
cytosine, thymine and uracil
Purines include
adenine and guanine
Base + ribose =
nucleoside
Base + ribosome phosphate =
nucleotide
Of deoxyribose, phosphates will react with the ______ on the _____ carbon or the ____ carbon.
Alcohols ; 3’ or 5’
Spontaneous deamination leads to _______. Water spontaneously reacts with _________ to form _____.
Uracil; cytosine, uracil ; A PROTEIN LOOKING FOR URACIL CAN’T DISTINGUISH IF IT WAS SUPPOSED TO BE THERE OR IF IT’S A PRODUCT OF DEAMINATION.
Why are nucleotide sequences synthesized 5’ to 3’?
3’ always attacks the phosphate of the 5’ of the growing DNA chain.
Edwin Chargaff (1950s)
Equal # of A to T, and Equal # of G to C
Rosalind Franklin (1950s)
- X-Ray diffraction of DNA
- The strong diffraction base on the reciprocal space was 1/d = 3.14 angstroms.
Jerry Donohue (1950s)
- Bases can be in keto or enol state; HOWEVER, almost always in keto state.
Endonuclease
Cleaves a nucleic acid within the polypeptide strand; CUT DNA at certain sequences.
Exonuclease
Cleaves a nucleic acid by removing one of its terminal residues.
Restriction Endonuclease
A bacterial enzyme that recognizes a specific DNA sequence and cleaves the DNA as part of a restriction-modification system.
Modification Methylase
A bacterial enzyme that methylates a specific sequence of DNA as part of a restriction-modification system.
The bases primarily exist in their ____ form.
keto
Why do G-C bonds have a higher melting temp. than A-T?
They have more hydrogen bonds than A-T
What is necessary for replication?
Complimentary bases
Transcription and Translation
DNA goes to transcription –> mRNA (codes for tRNAs) –> tRNA (translational RNA ; amino acids are attached to them) –> translation –> Bonds together to make a protein
mRNA is short-lived because
it is “chewed up” and translated to become a protein.
mRNA start codon
AUG
mRNA stop codon
UAG
Eukaryotes package DNA in
nucleosomes
DNA is wrapped around _____ ; These then stack on top of each other to make ______
Histones; chromatin
tRNA
- reads three bases at a time
- hydrogen bonds (good because it is reversible)
DNA Ligase
Adds phosphodiester bonds
Template strand of DNA is being sequenced from
3’ to 5’
Always read DNA strands from
5’ to 3’
The two strands of DNA are ______ but each forms a right-handed helix
antiparallel
The _________ occupy the core of the double helix .
aromatic bases
The ____________ run along the periphery, thereby minimizing the repulsions between charged phosphate groups
sugar-phosphate chains
The surface of the double helix contains two grooves of unequal width: the ______ and ______ grooves.
major and minor
Each base is _________ to a base in the opposite strand to form a ______ base pair
Hydrogen bonded ; Planar
Incoming dNTP is attacked at the _____ phosphate by the ____ hydroxyl of the growing DNA chain.
α ; 3’
The direction of ribosome movement on the mRNA is
5’ to 3’
Nucleotides participate in
- oxidation-reduction reactions
- Energy transfer
- Intracellular signaling
- biosynthetic reactions
Stem-loop structure is the result of
RNA bases pairing with themselves.
Molecular Cloning with Restriction Enzymes
The cloning vector and the foreign DNA are cut by the same restriction endonuclease –> The sticky ends of the vector and the foreign DNA fragments anneal and are covalently joined by DNA ligase –> Result: chimeric DNA containing a portion of the foreign DNA inserted into the vector
Polymerase Chain Reaction (PCR)
- An in vitro method for amplifying the amount of a particular DNA sequence.
1. Separate strands by heating, cooling, and annealing primers
2. Extend primers by DNA polymerase
3. Repeat steps 1 & 2
