Chapter 6 Flashcards
Bonds joining one nucleotide to another are covalent________
Phosphodiester bonds
The ability of a substance to change the genetic characteristics of an organism
Transformation
Attachment of the base to the deoxyribose sugar, addition of phosphate.
Nucleotide
Adenine, guanine
Purines
Thymine, cytosine.
Pyrimidines
Spacing between repeating units along the axis of the helix is 3.4 Å, the helix undergoes one complete turn every 34 Å, the diameter of the molecule is 20 Å.
Measurements of DNA
Spiral to the right
B form DNA
Spirals to the left and the backbone takes on a zigzag shape
Z form DNA
Retroviruses
Use RNA as their genetic material
Number one) Ribose instead of deoxyribose. Number two) RNA contains the base uricil instead of thymine which pairs with adenine. Three) Most RNA molecules are single stranded
Differences between RNA and DNA
Copying in which one strand of each new double helix is conserved from the parent molecule and the other is newly synthesized.
Semi conservative replication
Know the Meselson – stall experiment
Semi conservative replication
The high energy phosphate bonds required to synthesize every DNA molecule consists of four
Deoxynucleotide triphosphates (DATP, DCTP, DGTP, DTTP)
Number one. The 4DNTP’s Number two. The single-stranded template double-stranded DNA must be unwound. Number three. The primer with a free three prime hydroxyl group
Requirements for DNA replication
Proteins open up the double helix and prepare it for complementary base pairing
Initiation
Proteins connect the correct sequence of nucleotides on both newly formed DNA double helixes
Elongation
2 Y shaped areas
Replication forks
One newly synthesized strand that can grow continuously into each of the replication forks
Leading strand
Generated in pieces called OkaZaki fragments, The polarity of the _________ is opposite that the leading strand.
Lagging strand
Major role in producing the new strands of complementary DNA. Enzyme complex that adds nucleotides to the three prime end of a pre-existing strand of nucleic acid. Only functions in the five prime to three prime direction.
DNA polymerase III