DNA Structure and Replication
What are the three components of a nucleotide?
Nitrogenous base, pentose sugar, phosphate backbone
The central dogma of biology states that _____ transcribes DNA to RNA, and _____ translates RNA to proteins
RNA Polymerase, Ribosomes
This changes the mutated nucleotide back to its normal structure without excising the base.
Direct Repair
A(n) ______ is one of two or more versions of a gene
Allele
Name at least one graduate or undergraduate TA in your lab section
We're all very disappointed if you don't know our names yet
In the “beads on a string” model, what do the beads represent?
Nucleosomes (made up of DNA wrapped around histones)
Identify the three units of the transcription region of a gene.
Promoter, RNA coding region, terminator
What enzyme is involved in telomere repair?
Telomerase
This type of transposon does not use an RNA intermediate.
DNA transposons or Class II transposons
Which of the following animals has the largest number of chromosomes: humans, bananas, butterflies, or doves
Butterflies (up to 380 chromosomes)
What is meant by “semiconservative replication?”
Replicated DNA strands have one old half (template) and one new half
Identify the four stages of mRNA translation.
tRNA charging, initiation, elongation, termination
An indel will most often result in this type of DNA repair.
Mismatch Repair
Write an example of a nonsense mutation based on this wild type sequence:
Wild type: ACA AAG AGA GGT
Replace one codon with STOP (premature stop codon)
How much of human DNA is similar (percentage)
About 99.9%
How do DNA helicases and topoisomerases differ in function?
Helicases unwind; topoisomerases reduce torsion/supercoiling
What roles do tRNAs play in protein synthesis?
Read codon, transfer amino acid to the growing chain
What are the 2 common mechanisms of double-stranded DNA repair?
1) homologous recombination relies on replication of the template DNA strand; 2) non-homologous end joining ligates the break ends directly without the need for a homologous template
What is the hypothesis allowing for flexibility in base binding, leading to multiple codons per amino acid and replication-derived mutations?
Wobble Hypothesis
How much of your DNA encodes for proteins (hint: not as much as you might think)
About 1-2%
Why is DNA synthesis on the lagging strand discontinuous?
Replication goes 5’-3’, but lagging strand is 3’-5’ (reverse complement of leading)
What roles do the 5’ cap and 3’ tail of mRNA share?
Both increase mRNA stability, and facilitate attachment to the ribosome.
Many repair mechanisms are redundant meaning this.
Many types of DNA damage can be corrected by more than one pathway of repair
Microsatellites are commonly used in paternity testing and forensic identification. What feature of microsatellite loci ensures that they can reliably distinguish between individuals in a population?
Variation in the number of repeats
Why do some calico cats have larger color patches and some have smaller?
x inactivation occurs earlier in larger patches