DNA/RNA and the Code of Life Flashcards
AT which position, is there difference in the sugars in deoxyribose and ribose?
the 2’ carbon
True or False: you can find double stranded RNA somewhere in nature
Yes, in viruses. Not eukaryotes
DNA is read _____ and synthesized ______
Read 3’–> 5’, synthesized 5’–> 3’
What are the stop codons?
UGA, UAG, UAA
A mutation at the 3rd position of a codon is better than one at the 1st position. Why?
Wobble Hypothesis
What does degeneracy mean in terms of the genetic code?
Multiple codons code for the same amino acids so there is a little bit of room for error in replication
With 4 nucleotides, how many codon possibilities are there?
4^3, meaning there are 64 possibilities
B-DNA is _____ handed while Z-DNA is _______ handed
B-DNA is right handed, Z-DNA is left handed
How many nucleotides are there per turn?
10.5 approx
How far apart are the grooves of DNA?
about 34 angstroms or 3.4 x 10 ^-9 meters apart.
What is the major dna polymerase in prokaryotic replication?
DNA Poly III
A geneticist radiolabeled a fragment of dsDNA and allowed it to replicate. After four successive replication cycles, what proportion of the double-stranded DNA molecules contain at least one strand of the original parent material?
1/8
What purpose do primers serve in the initiation of DNA replication?
The provide binding sites for the necessary replication proteins. DNA polymerase catalyzes the elongation of new DNA strands. However, this enzyme cannot initiate DNA synthesis on its own, as it can only bind to a free –OH group that is already present on the developing strand. RNA primers provide these free 3′ hydroxyl groups.
Why does DNA polymerase have 3′-to-5′ exonuclease activity?
it can proofread
Replicates mitochondrial DNA
DNA Polymerase gamme
What strand would you call the top strand in the following schematic?
Leading strand
Identify the following:
Adenine
Identify the following:
Guanine
Identify the following:
Cytosine
Identify the following:
Thymine
Identify the following:
Uracil
What is the major structural difference between thymine and uracil?
Thymine has a methyl group where uracil just has a hydrogen. Both are single ringed (pyrimidines)
What are the major structural differences between adenine and guanine?
Guanine has both a carbonyl and an amine group whereas adenine has neither. Both are purines (double ringed) So if you need to ID them, know that double ringed means its either Adenine or Guanine. If it has more funtional groups on it, its guanine.
How can you tell the differences between the three pyrimidines?
Cytosine has just a primary amine group and no carbonyls while thymine and uracil have carbonyls. Thymine has a carbonyl AND an amine while uracil just has carbonyls.
What is the repeat code found in telomeres?
TTAGGG
True or False: Most human dna is junk dna
true
Name a cell type where you might find telomerases
Stem cell, germ line cell, cancer cells
In a murder invenstigation, DNA found at the scene appears to have 120 bp’s repeating in a non coding region. This repeat can be used to identify the killer. What is the name of this repeat?
VNTR- variable tandem repeat
Describe the role of acetylation in transcription activity
Histones are normally positively charged as lysine compose their tails. Acetylation masks this positive charge repelling DNA from the histone making it more accessible to the molecular machinery for transcription. Histone deacetylase then makes that positive charge accessible again thus shutting down transcription.
What is the name for the group of 8 histones wrapped 2xs in DNA?
Nucleosome
True or false: Centromeres contain highly conserved gene sequences.
This statement is false. Centromeres are the site of attachment for sister chromatids, and they contain repetitive DNA found as highly condensed heterochromatin. Although centromere structure is integral to cell function, the centromeric DNA sequence itself is not very highly conserved.
What does histone acetylation do?
Histone acetylation masks the positive charges onthe lsine residues of histone tails thus making the DNA more accessible
What amino acid residue makes up histone tails?
Lysine
Which cell types would you find telomerase in?
Stem cells and germ cells
What are the differenct classes of transposons?
Class 1–> RNA and reverse transcriptase, Class 2–> cut and paste
