Section 2: Structure of DNA
How many hydrogen bonds does A and T from?
2
How many hydrogen bonds does C and G form?
3
What are the base pairing rules?
The rules stating that DNA cytosine pairs with guanine and adenine pairs with thymine and that in RNA cytosine pairs with guanine and adenine pairs with uracil
Franklin's data helped Watson and Crick discover what?
The structure of DNA; a helix consisting of two strands that are regular, consistent width apart.
Watson and Crick determined the three-dimensional shape of DNA by -?
building models
In DNA, what does cytosine and adenine pair with?
cytosine pairs with guanine adenine pairs with thymine
In RNA, what does cytosine and adenine pair with?
cytosine pairs with guanine adenine pairs with uracil
What are "purines"?
double ring
How many rings does Adenine (A) have?
double-ring strcture
How mnay rings does Guanine (G) have?
double-ring strcture
Based on Chargaff's rules, the amount of A will be ____ the amount of T, and the amount of C will be ____ the amount of G.
equal to
What does a phosphate group consist of?
one phosphorus and four oxygens
DNA base pairing results in a molecule that has a unifrom width. A sugar phospahte backbone is on the -?
outside
All nucleotides have two parts that are the same: the deoxyribose sugar and the ________. The third part, _______ is different.
phosphate group, nitrogen containing base
What are "pyrimidines"?
single ring
How many rings does Thymine (T) have?
single-ring strcture
How many rings does Cytosine (C) have?
single-ring structure
Inside the structure, a base with two rings always pairs with a base with how may rings?
1
How many types of nucleotides are present in DNA?
4
What is a double helix?
A model that compares the structure of a DNA molecule, in which two strands wind around one another, to that of a twisted ladder
What nucelotide does the Thymine (T) nucelotide pair with?
Adenine (A)
What are Chargaff's rules?
Adenine (A) = Thymine (T) Cytosine (C) = Guanine (G)
What did Franklin's x-ray photographs show?
An X surrounded by a circle
What is a nucleotide?
An organic compound that consists of a sugar, a phosphate, and a nitrogenous base; the basic building block of a nucleic-acid chain
What occurs during x-ray crystallography?
DNA is bombarded with x-rays, the atoms in DNA diffract the x-rays in a pattern that can be captured on film.
What nucelotide does the Cytosine (C) nucelotide pair with?
Gaunine (G)
The nitrogen-containing bases from what type of bond?
Hydrogen bonds
The DNA double helix is similar to a spiral staircase. What is like the twisting handrails of the staircase?
Phosphate group and deoxyribose sugar
A ALWAYS pairs with ___, and C ALWAYS pairs with ___.
T, G
If one strand of the double helix is ACACAC, then the other strand is-?
TGTGTG
Does the double helix explain Chargaff's rules?
Yes, because A = T and C = G
What is a polymer?
a chain of repeating units
What do the nucleotides only differ in?
nitrogen-containing bases
What is like the steps that connect the railings to each other?
nitrogen-containing bases
Adenine (A) and Guanine (G) are-?
purines
Cytosine (C) and Thymine (T) are-?
pyrimidines
Franklin's data revealed that the structure of DNA is -?
uniform
What technique did Rosalind Franklin and Maurice Wilkins use when they were studying DNA?
x-ray crystallography
