Biochemistry: Nucleic Acid Structure and Function Flashcards
The phosphate group on a nucleic acid strand is usually found at what end: the 5’ end or the 3’ end?
5’ end of the nuclei acid strand on the pentose sugar
The hydroxyl group on the pentose sugar of the nucleic acid strand found at what end: the 5’ end of the 3’ end?
the 3’ end of the nuclei acid strand on the pentose sugar
Nucleotides are linked by what specific type of bonds?(include the numbers for the bonds)
3’-5’ phosphodiester bonds
What is significant about the 3’ and the 5’ end of a nuclei acid strand or a DNA molecule?
The fact that they’re distinct
The sequence of a nucleic acid strange are always conveyed in what direction?
5’ end tot he 3’ end
What type of nucleotides are found in the genome in eukaryotes? What is the exception?
dsDNA and ssRNA. Some viruses have dsRNA and ssDNA.
What is the structural formula of a DNA molecule and where do you find all of the significant bonds?(hydrogen bonds and phophodiester bonds)
What is Chargaff’s rule?
%G = % C and %T = %A and %purine = % pyrimidine
How many base pairs per complete turn of the DNA helix?
10 bases
Z-DNA is right handed or left handed?
left handed
Z-DNA is rich in what type of nucleic acid base pairs?
G-C
These drugs exert their effects by intercalating between the bases of DNA, thereby interfering with the activity of topoisomerase II and preventing proper replication of the DNA
doxorubin or danourubicin
What is the mechanism of danourubicin and doxorubicin?
intercalates between bases of DNA and interfere with the action of topoisomerase II
What drug binds tightly to the DNA, cauasing structural distortion and malfunction
cisplatin
Where is the major groove and the minor groove on a DNA molecule?
Denaturation of DNA takes place via what processes?(3 points)
heat, alkaline pH and chemicals
What are examples of chemicals that may denature DNA?(2 points)
urea and foramide
What is the general shape of mitochondrial DNA and DNA of most prokaryotes?
closed circular structures
What type of supercoiled DNA is used in most biologic reactions?
(-)
What is the difference betwen positive supercoiled and negative supercoiled?
Negative supercoiled is wound less tightly then Watson-Crick model and positive supercoil is wound more tightly than the Watsin-Crick model of the DNA
What is the basic packaging unit of chromatin?
nucleosome
A series of chromosome can be described structurally and numberically as what?
10 nm of chromatin fiber
The histone octamer is formed by what?
two copies of H2A, H2B, H3 and H4 histone proteins
What is the purpose of the H1 histone protein?
Histone H1 is associated with the linker DNA found between nucleosomes to help package them into a solenoid-like structure, which is a thick 30 nm fiber
How is DNA packaged in the chromatin structure?
The DNA is wound aroun the outside octamer, forming the nuclesome
How is DNA associated with the histone octamer?
it is wound around the outside of the histone octamer
Histones are rich in what type of amino acid?
Lysine and Arginine
What type of charge is on the histone protein
positive charge
Each eukaryotic chromosome in Go or G1 contains what specific type of DNA?
one linear molecule of dsDNA
What form of chromatin is more open and available for gene expression?
euchromatin
The special ribosome assembly occurs in what organelle/suborganelle in a eukaryotic cell?
nucleolus
A base compositional analysis that deviates from Chargaff’s rule is indicate of what?
single stranded nucleic acid molecule, not double stranded
The addition of a phosphate to a nucleoside converts it to what?
a nucleotide
Why is it important for the histone protein in the octamer molecules to have a positive charge?
the DNA has a negative charge, it facilitates better interaction
D
C
A
E
