Scientists
What scientist determined that A = T and G = C
Chargaff
The sugar in DNA is called...
deoxyribose
(DNA = deoxyribonucleic acid)
What are the steps of a DNA extraction with strawberry cells?
Mash (macerate)
Detergent
Enzymes
(Filter)
Alcohol
What is the complementary strand to this template strand of DNA: ACTTGATTT
TGAACTAAA
Watson and Crick were the first scientists to use __________________ in order to try to figure out the structure of DNA.
physical models
What parts of a nucleotide make up the DNA backbone?
sugar and phosphate group
Why is alcohol added at the end of a DNA extraction?
It isolates the DNA from the rest of the cell mixture.
What is the enzyme that unzips DNA?
helicase
What was Oswald Avery's experiment, and what did it help him to discover?
Avery used extracts (isolating the proteins, DNA, and RNA) of the different parts of the S strain of pneumonia, and he injected those into mice with the harmless R strain to see which part of the S strain was causing the change. He discovered that DNA is the genetic material, not RNA or proteins.
What is the force (specific name) holding bases together in DNA, and is this intra- or inter-molecular?
(you must get both parts right to get points)
Hydrogen bonds
inter-molecular (weaker)
What do enzymes do in a DNA extraction?
What is an origin of replication?
a place where helicase starts replication by unzipping, which forms a little "bubble" in the DNA. Any one strand of DNA will have hundreds of origins of replication at once in order to speed up the process
Hershey and Chase used radioactive tagging. What two specific atoms did they tag, and why?
Phosphorus, because it is only present in DNA; sulfur, because it is only present in proteins
This allowed them to see where the proteins and DNA each ended up, and more importantly, which one was injected into cells
What are the intramolecular forces holding DNA together (name the specific type of bond) and where do they occur in the DNA structure?
Phosphodiester bonds (a type of covalent bond)
These occur between the phosphate groups in the DNA backbone (sides of the ladder)
How do detergents work? (Not just what they do, but how they do it)
They are non polar, so they can surround the non polar tails of phospholipids so they don't need to remain in a bilayer. This allows them to break the membranes of the cell and the nucleus.
What are the two jobs of DNA polymerase? (you must get both to get points)
adding nucleotides and proofreading
Griffith discovered that there is a transforming principle. What does transforming principle mean, or what is it describing? (Not what it was later discovered to be.)
Transforming principle = some molecule that can be passed between organisms in order to determine certain traits
What is the difference between purines and pyrimidines (which one is which)?
A and G are purines, which have two rings
T and C are pyrimidines, which have one ring
Other than the amount of strawberries or the amount of alcohol added, what is something that could have caused one group to get more DNA than another group?
how much of the strawberry was not lost in transfer
whether or not they popped the bag or filter
how much liquid they got out of the filter
how well they mixed the buffer with the mashed strawberries
how little they disturbed the mixture after adding the alcohol...
What does it mean that DNA is semiconservative?
Every new strand of DNA is half new, half old.