CHAPTER 5 - NUCLEIC ACID Flashcards
What are the three parts that every DNA nucleotide has?
- A deoxyribose sugar
-A phosphate group - A nitrogenous base
—–> 4 types (in DNA): Adenine (A), guanine (G), thymine (T), or cytosine (C)
What are the difference between purines and pyrimidines?
Both Nitrogenous bases are the same width, however…..
-Purines are larger ( 2 rings) Adenine and Guanine
-Pyrimidines are smaller ( 1 ring) Cytosine and Thymine
What does deoxyribose sugar contain?
-It’s a sugar that contains five carbon atoms= ribose
- Missing one oxygen= deoxy
The corners of the sugar are carbon atoms #ed from 1’ to 5’
And this is how you determine the 5’ and 3’ ends of any DNA nucleotide
How do you tell which is 5’ and which is 3’
DNA nucleotides form a long DNA strand by joining a 5’ phosphate group to a nucleotide and 3’ carbon to another.
Which end can accept a new nucleotide ?
only 3’
Why can only the 3’ ends of strands accept new nucleotides?
Since the 5’ phosphate-holding end of the new nucleotide that needs to bind, the nucleotide must attach itself to the 3’ end of the growing stand.
What is the DNA strand is held together by?
Backbone, sugar and phosphate groups and the nitrogneous bases. The 4 bases act like letters in the alphabet of the nucleic acid language. The info held by DNA is determined by the sequence of theses bases in a strand.
How do you know what nitrogenous base letter to add to the 3’?
DNA & RNA strands are always synthesized beside a template strand.
So as DNA polymerase reads the next letter on the template strand it makes sure that the new nucleotide is complementary before adding it to the new strand.
The primary structure of a DNA polymer is the sequence of nucleotides bonded together by ……..?
strong covalent bonds.
What is our DNA made out of?
two antiparallel strands, held together by weaker hydrogen bonds.
