L01 DNA Structure

Question 1

T/F

A cell can use copies of RNA to make DNA.

Answer 1

True. A cell can use reverse transcription.

Question 2

Who coded the term gene?

Answer 2

Wilhelm Johannsen

Question 3

Who used bacteriophages to prove that DNA is the genetic material?

Answer 3

Martha Chase and Alfred Hershey at Cold Spring Harbor, 1953.

Question 4

How did Erwin Chargaff quantify the make of DNA?

Answer 4

Chargaff’s Base Pair Ratio Experiment

Nucleotides quantified by chromatography.

Question 5

Watson and Crick deduced the double helical structure of DNA from all of the following except

A. Biophysical data
B. Scale Model Building
C. Franklin
D. Chase Rule

Answer 5

D. Chase’s Rule (Should be Chargaff’s Rule)

They used the following:

X-ray diffraction pattern of Franklin

The base ratios of Chargaff’s rule

Biophysical data, e.g. the water content of DNA fibers.

Scale Model Building.

Question 6

What are the components of Deoxyribonucleic acid?

Answer 6

Nitrogenous base, pentose sugar and a phosphate group

Question 7

In eukaryotic DNA packaging, approximately how wide are the solenoid structures?

A. 2nm
B. 10nm
C. 20nm
D. 30nm

Answer 7

~30 nm wide and 2 m long

Question 8

DNA is referred to as:

A. Primary Structure
B. Secondary Structure
C. Tertiary Structure
D. Quaternary Structure

Answer 8

D. Quaternary Structure

In eukaryotes, linear DNA is complexed to histones(proteins) to form highly dense structures often referred to as a quaternary Structure.

Question 9

Linker DNA consist of

A. 45bp
B. 54bp
C. 146bp
D. 164bp

Answer 9

B. 54

Linker DNA consists of about 54 base pairs.

Question 10

What is the helix geometry of RNA form?

A. B-DNA (Right-handed)
B. A-DNA (Right-handed)
C. Z-DNA (Left-handed)
D. None of the above

Answer 10

B. A-DNA (Right-handed)

Question 11

WHAT IS THE DIFFERENCE BETWEEN NUCLEAR DNA AND MITOCHONDRIAL DNA?

Answer 11

NUCLEAR GENOME
24 LINEAR MOLECULES
22 AUTOSOMAL PAIRS
2 SEX CHROMOSOMES
25,000 GENES

MITOCHONDRIAL GENOME
CIRCULAR DNA
16,569 BASE PAIRS
37 GENES

Question 12

WHAT DID MENDEL & MIESCHER DISCOVER?

Answer 12

MENDEL: GENES & HEREDITY

MIESCHER: NUCLEIC ACID THAT CONTAINED BOTH PHOSPHORUS & NITROGEN

Question 13

EXPLAIN THE GRIFFITH EXPERIMENT & CONCLUSION.

Answer 13

GRIFFITH CONDUCTED A MICE STUDY IN WHICH HE INJECTED THE MICE WITH NON-VIRULENT (ROUGH PNEUMOCOCCUS), VIRULENT (SMOOTH PNEUMOCOCCUS), HEAT-KILLED VIRULENT, AND A COMBINATION OF HEAT-KILLED VIRULENT AND NON-VIRULENT BACTERIA.

THE COMBINATION OF HEAT KILLED VIRULENT AND NON-VIRULENT RESULTING IN DEAD MICE AND THE ABILITY TO ISOLATE VIRULENT BACTERIA, WHICH INDICATED A TRANSFORMING FACTOR THAT THE HEAT-KILLED VIRULENT WERE ABLE TO TRANSFER TO THE NON-VIRULENT, MAKING THEM TO BECOME VIRULENT.

Question 14

EXPLAIN HOW AVERY USED THE GRIFFITH EXPERIMENT TO MAKE HIS DISCOVER & WHAT DID HE DISCOVER.

Answer 14

AVERY CONDUCTED THE SAME EXPERIMENT AS GRIFFITH BUT ALSO TREATED THE COMBINATION OF NON-VIRULENT & WITH HEAT-KILLED VIRULENT WITH PROTEASE, RIBONUCLEASE, AND DEOXYRIBONUCLEASE.

MICE ONLY SURVIVED WHEN TREATED WITH DEOXYRIBONUCLEASE, WHICH INDICATED THAT THE TRANSFORMING FACTOR WAS DNA.

Question 15

HOW DID CHASE & HERSHEY CONFIRM AVERY’S EXPERIMENT?

Answer 15

CHASE & HERSHEY USED BACTERIOPHAGE TO INFECT BACTERIA WITH THE BACTERIOPHAGE’S DNA. THEY LABELLED THE BACTERIA PROTEIN CAPSULE WITH SULFER & THE DNA WITH PHOSPHORUS.

AFTER INFECTION & THEN CENTRIFUGATION, SULFER WAS RICH IN THE SUPERNATANT & PHOSPHORUS WAS RICH IN THE BACTERIA PELLET.

CONFIRMATION THAT DNA IS THE HEREDITARY INFORMATION, SINCE IT WAS FOUND IN THE BACTERIA.

Question 16

WHO QUANTIFIED THE NUCLEOTIDE OF DNA?

Answer 16

CHARGAFF

HE DISCOVERED THAT
A=T & G=C
50% PURINES
50% PYRIMIDINES

Question 17

HOW DID FRANKLIN’S X-RAY ASSIST IN DISCOVERING THE STRUCTURE OF DNA?

Answer 17

IT SHOWED THAT DNA WAS SYMMETRICAL & CONSISTENT

Question 18

WHO DISCOVERED THE FULL STRUCTURE OF DNA?

Answer 18

WATSON, CRICK, & WILKINS

Question 19

COMPARE DNA & RNA

Answer 19

DNA
DEOXYRIBOSE
A, G, T, C
DOUBLE-STRANDED
B-FORM
CAN BE DAMAGED BY UV
ANTI-PARALLEL

RNA
RIBOSE
A, G, U, C
SINGLE-STRANDED
A-FORM
RESISTANT TO UV DAMAGE

Question 20

WHAT IS THE DIFFERENCE BETWEEN DEOXYRIBOSE & RIBOSE?

Answer 20

THE C2 OF RIBOSE STRUCTURE HAS HYDROGEN ATTACHED AND NOT HYDROXYL, WHILE C3 HAS HYDROXYL GROUP ATTACHED

C2 & C3 OF RIBOSE BOTH HAVE HYDROXYL GROUP ATTACHED.

Question 21

HOW ARE NUCLEOTIDES LINKED TO EACH OTHER?

Answer 21

NUCLEOTIDES ARE LINKED BY PHOSPHODIESTER BONDS AT THE 3’ END OF ONE NUCLEOTIDE TO THE 5’ END OF THE FOLLOWING NUCLEOTIDE

Question 22

HOW DO PROKARYOTES PACK THEIR DNA?

Answer 22

PROKARYOTIC DNA IS CIRCULAR, THEREFORE THEY UTILIZE SUPERCOILING AND HU PROTEINS TO PACK THEIR DNA

Question 23

HOW DO EUKARYOTES PACK THEIR DNA?

Answer 23

EUKARYOTES HAVE LINEAR, DOUBLE STRANDED DNA, SO THEY BEGIN WITH A DOUBLE-HELIX, WHICH IS THEN WRAPPED AROUND A HISTONE OCTOMER (NUCLEOSOME CORE). THE DNA IS KEPT AROUND THE NUCLEOSOME BY THE H1 HISTONE PROTEIN. THE NUCLEOSOMES ARE THEN LINKED TOGETHER BY LINKER DNA (“BEADS ON A STRONG”) FOLLOWED BY LINKING OF H1 PROTEINS TO FORM A CHROMATIN 30NM FIBER, ALSO KNOWN AS THE SOLENOID.

Question 24

WHAT KEEPS THE DNA TIGHTLY COILED AROUND THE NUCLEOSOME?

Answer 24

H1 HISTONE PROTEIN

Question 25

WHAT ARE THE FUNCTIONS OF DNA?

Answer 25

STABLE LONG-TERM STORAGE
REPLICATION
EXPRESSION
EVOLUTION/MUTATION

Question 26

EXPLAIN THE FLOW OF GENETIC INFORMATION.

Answer 26

GENOME (DNA) to TRANSCRIPTOME (RNA to ) PROTEOME (PROTEINS)

TRANSCRIPTION to TRANSLATION

Question 27

WHICH PART OF THE GENETIC FLOW ALLOWS FOR GENE EXPRESSION?

Answer 27

TRANSCRIPTION FROM DNA TO RNA/ GENOME TO TRANSCRIPTOME

Question 28

A DNA sample was found to contain approximately 27% Adenine. What is the expected ratio of Thymine: Guanine?

Answer 28

27: 23
A=T; G=C; 27% A = 27%T
A+G = 50%; T+C = 50%
27% + G = 50%; G=23%