DNA structure & 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
___ is one of two or more versions of a gene
Allele
Cell theory proposed by Schleiden and Schwann concluding that the ____ contains the hereditary information (think location/organelle)
Nucleus
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?
This type of transposon does not use an RNA intermediate
DNA transposons or Class II transposons
Name one correct theory of heredity and briefly explain that concept.
Germ Plasm Theory, Cell Theory, or Mendelian Inheritance
(Traits are passed from generation to generation
Transmission of genetic information from parents to offspring)
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 wildtype sequence:
Wildtype: ACA AAG AGA GGT
Premature stop- adding TAG, TAA or TGA or STOP
T replaces U since it is DNA and will encode RNA UAG, UAA, UGA
Phoebus Levene incorrectly proposed the ____ hypothesis that DNA was composed of repeating identical groups of four nucleotides.
Tetranucleotide hypothesis
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, and can lead to both multiple codons per amino acid and replication-derived mutations?
Wobble hypothesis
What is Chargaff’s Rule?
Amount of adenine proportional to thymine and guanine is proportional to cytosine
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, which means...
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
What is Lyon’s hypothesis?
Random inactivation of X chromosomes in somatic cells leads to all descendant cells having the same X chromosome inactivated