Chapter 14 Flashcards
Discovered DNA
Friedrich Miescher
3 main components of DNA
- Five carbon sugar
- Phosphate (PO4) group
- A nitrogenous base
Bases may be :
Purine- adenine , A, or guanine, G,
Pyrimidine- thymine ,T, or cytosine, C
RNA - has pyrimidine uracil,U,
Chargaffs rules
- Proportion of A always equals that of T and the proportion of G always equals that of C. ( A=T ; G=C)
- A/T and G/C proportions vary widely in species
The two strands of double helix are referred as the
Phosphodiester backbone
What is the complementary strand sequence of TACG
ATGC
Native double stranded DNA always has the __________ configuration
Antiparallel
Who created the Model of DNA structure
Watson Crick
Phosphates are connected to the deoxyribose sugar by
Phosphodiester bonds
In a strand of DNA the 3’ C attaches to phosphate group and then attaches to the ______
5’-Carbon
The base is always attached to which carbon
1’-Carbon
One molecule of DNA when it replicates each new daughter molecule will consist of one new strand and one old strand this makes DNA replication _______
Semi conservative
What are the bases in a DNA molecule held together by
Hydrogen bonds
How many hydrogen bonds hold A and T together
3
How many hydrogen bonds hold G and C bases together
2
If one stranded had a 5’ -C beginning and a 3’- C end what would the 2nd strand begin and end with? This makes them ______
3’-C and 5’ -C;
Anti parallel
Which characteristics of DNA allows each strand of molecule to act as a template that specifies the exact sequence of nucleotides in the other strand
Complementarity of the bases
What is the order of proteins that participate in DNA replication
- Helicase
- Single strand binding proteins
- Primase
- DNA polymerase III
UV light damages DNA by causing
Covalent bonds to form between thymine nucleotides next to each other on the same DNA strand
Thymine dimer weakens_____
Hydrogen bonding and leads to mutations
What enzyme is responsible for repairing thymine dimers using the energy of light
DNA photolyase
Which protein has a helicase function
UvrD
The covalent bonds between the thymine dimers are broken in
Light repair