DNA= Dont and Az Flashcards
What does DNA stand for
Deoxyribonucleic acid
Function of DNA
DNA contains the genetic instructions/hereditary information needed for an organism to develop, survive and reproduce
A DNA nucleotide is composed of three units:
Phosphate group
5-carbon sugar (Deoxyribose)
Nitrogenous base
What are the Nitrogenous bases
Adenine (A), thymine (T), guanine (G), and cytosine (C)
What shape is DNA
Double helix (The presence of two strands (twisted ladder))
Base parings?
Adenine (A) & Thymine (T)
Guanine (G) & Cytosine (C)
What is the base paring rule
The percentage of adenine (A) will equal the percentage of thymine (T), and the percentage of cytosine (C) will equal the percentage of guanine (G). Together, these percentages will add to 100%.
Hydrogen bonds and Number Between Pairs
A & T - two hydrogen bonds
C & G - three hydrogen bonds
Rosalind Franklin what did she discover
Discovered the double helix structure by the use of x-ray crystallography, and took a photo of it (known as “Photo 51”)
Watson and Crick what did they discover
-Proposed the double helix model
-Stole Rosalind Franklin’s double helix structure
-Realized that DNA was made up of two chains of nucleotide pairs that encode the genetic information for all living things
Erwin Chargaff #PAY
-Reported that the base composition varies from one species to another
–In 1949, Chargaff discovered that the proportions of bases in DNA depend on the species the DNA comes from
—The amount of guanine should be equal to the amount of cytosine and the amount of adenine should be equal to the amount of thymine
—-1:1 ratio of purine and pyrimidine bases (A+G = T+C ) should exist
——–The perfects of A and T/G and C bases are roughly equal (kahoot answer)
Frederick Griffith
Accidentally discovered that pathogenicity traits (traits that cause disease) are passed by descendants of bacteria
What is DNA replication
when Dna creates new copies of itself
Model is semi-conservative (what does that mean?)
-The two strands of DNA unwind from each other, and each acts as a template for synthesis of a new, complementary strand
–This results in two DNA molecules with one original strand and one new strand
Why does DNA Replicate
Replication is an essential process because whenever a cell divides, the two new daughter cells must contain the same DNA (genetic information) as the parent cell
Steps of DNA Replication
- Helicase unzips the DNA (breaking the bonds)
- DNA polymerase travels down the molecule adding bases following the complementary base pairing rules (A&T) (C&G)
- Bases are added in 5’ (‘ = prime) 3) direction in the direction of the replication fork
- Both sides are opposite directions (antiparallel) leading strand made continuously - lagging strand made in fragments (Okazaki)
- DNA polymerase double checks for eros
5 1/2. Each original DNA molecule acts as a template for the new strand
Leading vs. Lagging Strand
-Leading is Synthesized by adding nucleotides to the 3’ end of the growing strand and Synthesized in short fragments that are ultimately stitched together (Okazaki)
-Lagging is Strand created in pieces, Synthesized by adding nucleotides to the 5’ end ,synthesized continuously
Enzymes and functions
Helicase
Unwinds the double helix by breaking hydrogen bonds
Enzymes and functions
DNA Polymerase
Travels down the molecule adding bases
Enzymes and Functions
Ligase
Joins the Okazaki fragments by gluing them together
The Hershey Chase experiment proved
That proteins don’t make up hereditary material
That nucleic acid are the hereditary material
That enzymes are the hereditary material
