BIOL 253 Exam 3 UPDATED ACTUAL
Exam Questions and CORRECT Answers
Griffith's experiment - CORRECT ANSWER - - an experiment carried out by Griffith
using the heat-killed bacteria in mice to discover that a factor in heat-killed, disease-causing
bacteria can "transform" harmless bacteria into ones that can cause disease
- transformation
Avery, MacLeod, McCarty - CORRECT ANSWER - Determined that DNA was
Griffith's "Transforming Factor."
Rosalind Franklin - CORRECT ANSWER - Used X-ray diffraction to discover the double-
helical structure of DNA.
Wilkins - CORRECT ANSWER - showed Watson and Crick the photograph of DNA that
led to their discovery of the double helix
Chargaff's Rule - CORRECT ANSWER - [A]=[T] and [G]=[C], they pair up across from
one another forming two strands also called base pairing.
Chargaff - CORRECT ANSWER - The individual responsible for discovering the base
pairing rules for DNA.
How many H bonds between A and T? - CORRECT ANSWER - two
How many H bonds between C and G - CORRECT ANSWER - 3 H bonds
What are genomes made of? - CORRECT ANSWER - DNA
DNA vs RNA - CORRECT ANSWER - DNA: 2' C; grows in the 3' direction
, RNA: 2' OH (unstable)
Kary Mullis - CORRECT ANSWER - invented PCR
PCR (polymerase chain reaction) - CORRECT ANSWER - A laboratory technique for
amplifying DNA in vitro by incubating with special primers, DNA polymerase molecules, and
nucleotides.
What nitrogenous bases are on the ends of PCR Primers? - CORRECT ANSWER - G-C
rich ends to anchor it
Hydrogen bond strength - CORRECT ANSWER - weak, easily unzipped, 95 degrees C to
break the H bond
Covalent bond strength - CORRECT ANSWER - strong
Epigenetics - CORRECT ANSWER - involves methylation of cytosine
DNA methylation - CORRECT ANSWER - The addition of methyl groups (—CH3) to
cytosine of DNA after DNA synthesis; may serve as a long-term control of gene expression.
What does methylation do? - CORRECT ANSWER - prohibits expression, prevents
polymerase from doing their job
Topoisomerase - CORRECT ANSWER - corrects "overwinding" ahead of replication forks
by breaking, swiveling, and rejoining DNA strands
Histone proteins - CORRECT ANSWER - A simple protein bound to DNA, involved in
the coiling of chromosomes.
Exam Questions and CORRECT Answers
Griffith's experiment - CORRECT ANSWER - - an experiment carried out by Griffith
using the heat-killed bacteria in mice to discover that a factor in heat-killed, disease-causing
bacteria can "transform" harmless bacteria into ones that can cause disease
- transformation
Avery, MacLeod, McCarty - CORRECT ANSWER - Determined that DNA was
Griffith's "Transforming Factor."
Rosalind Franklin - CORRECT ANSWER - Used X-ray diffraction to discover the double-
helical structure of DNA.
Wilkins - CORRECT ANSWER - showed Watson and Crick the photograph of DNA that
led to their discovery of the double helix
Chargaff's Rule - CORRECT ANSWER - [A]=[T] and [G]=[C], they pair up across from
one another forming two strands also called base pairing.
Chargaff - CORRECT ANSWER - The individual responsible for discovering the base
pairing rules for DNA.
How many H bonds between A and T? - CORRECT ANSWER - two
How many H bonds between C and G - CORRECT ANSWER - 3 H bonds
What are genomes made of? - CORRECT ANSWER - DNA
DNA vs RNA - CORRECT ANSWER - DNA: 2' C; grows in the 3' direction
, RNA: 2' OH (unstable)
Kary Mullis - CORRECT ANSWER - invented PCR
PCR (polymerase chain reaction) - CORRECT ANSWER - A laboratory technique for
amplifying DNA in vitro by incubating with special primers, DNA polymerase molecules, and
nucleotides.
What nitrogenous bases are on the ends of PCR Primers? - CORRECT ANSWER - G-C
rich ends to anchor it
Hydrogen bond strength - CORRECT ANSWER - weak, easily unzipped, 95 degrees C to
break the H bond
Covalent bond strength - CORRECT ANSWER - strong
Epigenetics - CORRECT ANSWER - involves methylation of cytosine
DNA methylation - CORRECT ANSWER - The addition of methyl groups (—CH3) to
cytosine of DNA after DNA synthesis; may serve as a long-term control of gene expression.
What does methylation do? - CORRECT ANSWER - prohibits expression, prevents
polymerase from doing their job
Topoisomerase - CORRECT ANSWER - corrects "overwinding" ahead of replication forks
by breaking, swiveling, and rejoining DNA strands
Histone proteins - CORRECT ANSWER - A simple protein bound to DNA, involved in
the coiling of chromosomes.
