Lecture 4

Question 1

Central Dogma of Molecular Biology

Answer 1

The principle of directional information flow from DNA to RNA to protein

Question 2

Genetic Code

Answer 2

A triplet code in which combinations of three bases specify amino acids, degenerate and non-overlapping

Question 3

Frameshift Mutations

Answer 3

Insertion or deletion of a nucleotide causing a shift in the reading frame

Question 4

Primary Transcript

Answer 4

A newly produced RNA molecule

Question 5

RNA Processing

Answer 5

Chemical modifications made to the primary transcript, including the removal of sequences and addition of 5’ caps/3’ tails

Question 6

Poly(A) Tail

Answer 6

A long stretch of adenines (50 to 250 nucleotides) added to the 3’ end of an mRNA transcript, protects the mRNA from nucleases and is required for export of the transcript to the cytoplasm

Question 7

5’ Cap

Answer 7

A guanosine that is methylated at position 7 of the purine ring, protects the mRNA from nucleases and plays a role in positioning the mRNA on the ribosome

Question 8

RNA Splicing

Answer 8

The process of removing introns and joining the exons, splicing errors commonly cause inherited human diseases

Question 9

Spliceosome

Answer 9

Large molecular complex consisting of 5 different RNA molecules and many proteins, catalyzes the removal of introns

Question 10

snRNPs

Answer 10

Small nuclear ribonucleoprotein complexes, help spliceosomes assemble, contain 1 or 2 snRNA molecules

Question 11

Ribozymes

Answer 11

RNA molecules that function as catalysts

Question 12

Missense Mutation

Answer 12

A codon mutation which alters only a single amino acid

Question 13

Silent Mutation

Answer 13

A codon mutation which does not alter the amino acid, but can still have an effect on splicing or ribosome stalling

Question 14

Nonsense Mutation

Answer 14

A codon mutation which converts an amino acid-coding codon into a stop codon, leading to incomplete, nonfunctional polypeptides

Question 15

Nonstop Decay

Answer 15

When there is no stop codon RNA degrading enzymes bind the stalled ribosome to degrade the defective mRNA

Question 16

Nonsense Mediated Decay

Answer 16

mRNA molecules with premature stop codons will be degraded as long as premature stop is not in the final exon

Question 17

Centrifuge

Answer 17

A piece of equipment that consists of a rotor that can be be spun rapidly in a circular motion by an electric motor

Question 18

Sedimentation Coefficient

Answer 18

Measure of how rapidly a particle sediments when subjected to centrifugation, measured in Svedbergs

Question 19

Subcellular Fractionation

Answer 19

Using centrifugation to isolate and purify organelles and macromolecules based on their sedimentation rates and density