Exam 1: Intro to Genetics, Intro to DNA, Mendel's Laws, etc Flashcards
Name features of Model Organisms
-Short reproductive cycle
-Give birth to lots of offspring
- Low maintenance
-Easy to observe phenotypes
What is the primary structure of DNA?
Deoxyribonucleotides
What is the secondary structure of DNA
- Double Helix
-Hydrogen bonds + base pairs - Antiparallel complementary DNA strands
What is a nucleotide?
the building block of nucleic acids
-> phosphate, ribose sugar, base
What is a pyrimidine?
a 1 ring base
What are examples of pyrimidines?
Cytosine, thymine, uracil
What is a purine?
double ring base
What are examples of purines?
Adenine and Guanine
What charge does DNA have?
Negative charge
Explain Chargaff’s base pairing Ratio Rule
%Adenine = % Thymine
% Guanine = %Cytosine
How do you distinguish between:
-double strand DNA
-single strand DNA
-RNA
Double strand: true Chargaff ratios
Single strand: A= 2T and C=3G
RNA: Uracil present
How many hydrogen bonds with A-T?
2 H bonds
How many hydrogen bonds with G-C
3 H bonds
What was a piece of evidence that gave proof that the structure of DNA was a double helix?
Photo-51 by Rosalind Franklin (Xray photography)
X shape in photo= double helix
Name and describe the three types of Secondary DNA Structures
A Form- very compressed
B Form- in the middle
Z form- Very stretched
Describe Griffith’s Transformation Experiment
S- strain= smooth colony- fatal
R- strain= rough colony- not fatal
Living R and heat killed S was injected into a mouse, it died and alive S strain was found in the mouse.
A completely destroyed S strain didn’t effect mice. No conclusion drawn until Avery and MacLeod and McCarty’s
Describe Avery and MacLeod and McCarty’s experiment
-Like Griffith’s experiment, but in test tubes
-Get bacteria transformation to work
-Then, test the heat killed smooth cell extracts by removing one type of molecule at a time
Only the DNase treated cells didn’t transform into S cells= DNA is the required transforming material!
Nothing from carbohydrates, RNA, proteins
Describe the Hershey Chase Phage Labeling experiment
-Labeled Phage DNA with 32 P
-Labeled Phage protein 35 S
When the phage infected the cell, and was knocked off, only the labeled DNA infected the cell with 32 P, while the bacteriophage labeled with 35 S didn’t successfully infect the cell
Conclusion: DNA (not protein) is the genetic material, sufficient information molecule.
Describe the Tobacco Mosaic Virus
-RNA genome
- Has a hollow protein coat
-Rosalind Franklin worked with these to show that the viral RNA was single stranded
Describe the Fraenkal-Conrat and Singer Experiment
-Viruses will self assemble
-Mix and match protein coat from RNA core
Conclusion: RNA is the information molecule!