Exam 4 Flashcards
(87 cards)
Three parts of a DNA nucleotide
Phosphate Deoxyribose sugar Nitrogenous base
How does an RNA nucleotide differ from a DNA nucleotide?
DNA nucleotides, or deoxyribonucleotides, have a deoxyribose sugar that lacks an oxygen molecule at the 2’ carbon of the sugar molecule. Ribonucleotides, or RNA nucleotides, have a ribose sugar with oxygen linked to the 2’ carbon of the sugar molecule. Ribonucleotides may contain the nitrogenous base *uracil* but NOT the thymine. DNA nucleotides contain *thymine*, but not uracil.
Draw the three parts of a DNA nucleotide.

Draw the difference between an RNA nucleotide vs DNA nucleotide.

a more stable double-stranded form that stores the genetic blueprint for cells
DNA
a more versatile single-stranded form that transfers the genetic information for decoding
RNA
two types of nucleic acids present in cells
DNA and RNA
Both DNA and RNA are ______ of nucleotides
polymers
How does a purine differ from a pyrimidine?
A purine consists of a six-sided ring attached to a five-sided ring.
What purines and pyrimidines are found in DNA and RNA?
In both DNA and RNA, the purines found are adenine and guanine. DNA and RNA differ in the pyrimidine content. The pyrimidine cytosine is found in both RNA and DNA., However, DNA contains the pyrimidine thymine, whereas RNA contains the pyrimidine uracil but not thymine.
Draw a purine vs pyrimidine.

Draw a short segment of a single polynucleotide strand, including at least three nucleotides. Indicate the polarity of the strand by identifying the 5’ end the 3’ end.

Which bases are capable of forming hydrogen bonds with each other?
Adenine is capable of forming two hydrogen bonds with thymine. Guanine is capable of forming three hydrogen bonds with cytosine.
Name the purines.
Think “GAP”.
Guanine and Adenine are the purines.
Name the pyrimidines.
Think “CUT to the rim”.
Cytosine, Uracil and Thymine.

Adenine

Guanine

Cytosine

Thymine

Uracil
One nucleotide strand of a DNA molecule has the base sequence illustrated below.
5’–ATTGCTACGC–3’
Give the base sequence and label the 5’ and 3’ ends of the complementary DNA nucleotide strand.
5’–ATTGCTACGC–3’
3’–TAACGATGCG–5’
If a double-stranded DNA molecule is 15% thymine, what are the percentages of all the other bases?
15% thymine = 15% adenine
35% guanine = 35% cystosine
What functions does supercoiling serve for the cell?
Supercoiling compacts the DNA. Negative supercoiling helps to unwind the DNA duplex for replication and transcription.
Any group of basic proteins found in chromatin
histones






