Chapter 12 - DNA Flashcards
Who concluded that bacteria could be transformed from harmless to disease causing by an unknown factor?
Griffith
Who concluded that DNA was the factor that caused one bacterium to transform into another?
Avery
Who concluded that the genetic material of a bacteriophage is DNA?
Hershey and Chase
Who discovered that percentages of Adenine and Thymine were almost the same in any sample of DNA. and the same occurred for Guanine and Cytosine?
Chargaff
called “Chargaff’s rule”
Who concluded using an x-ray that DNA was in the shape of a double helix and that nitrogenous bases are near the center of the DNA molecule?
Franklin
Who discovered the structure of the DNA molecule (based of Franklin’s work)?
Watson and Crick
What did Watson and Cricks model show about DNA?
The two strands of DNA run in anti parallel
Hydrogen bonds held together the two strands of DNA
Explained and gave proof to Chargaff’s rule
During DNA replication, the DNA molecule does what?
It separates into two strands
At the end of DNA replication how many NEW strands of DNA are there?
Two new strands
At the end of DNA replication, how many strands (new and original) are there?
Four strands
New DNA is replicated in strands complimentary to the Original DNA, because production of new DNA follows the rules of
base parings
What are DNA’s 3 jobs
Give instructions to assemble proteins
Direct REPLICATION of genes (meiosis)
Direct process of how genes pass from parent to offspring
What is DNA
a nucleic acid (polymer) made of nucleotides (monomers)
The nucleotides are joined by covalent bonds (sugar to phosphate)
Can be thousands of nucleotides long
What is a nucleotide made of
sugar, deoxyribose (a phosphate group), and a nitrogenous base
What are the four Nitrogenous bases?
Adenine (A), Thymine (T),
Cytosine (C), Guanine (G)
What bases always go together and have the same percentage (Chargaff’s rule)
A = T C = G
How do two strands of DNA join
They join by hydrogen bonds, because they are strong enough to hold it together, but weak enough to break apart when needed
what is the shape of DNA
double helix (twisted ladder)
What bases are Pyrimidines
Cytosine and Thymine. They both have one ring
1y=1 ring
what bases are Purines
Adenine and Guanine. They both have two rings.
2ns’=2 rings
why are the “rungs of the ladder” 3 bases wide?
so that DNA is more stable, more integrity, and resists damage. (A=2 + T=1 = 3) (G=2 + C=1 = 3)
what is the backbone of DNA made of?
the outside sticks of ladder
alternating sugars and phosphates
How are the DNA strands Anti parallel
3 prime on one end and 5 prime on other end of one strand means on other strand; 5 prime on end opposite of other 5 prime, and 3 prime on other end of strand, opposite of 3 prime of other end
How does the original strand act as a template for new strand?
the original is a template because the new strand must be complementary (using Chargaff’s rule) to original strand
