Chapter 10 and 12.4- DNA Structures and Chromosomes Flashcards
What is the tetranucleotide hypothesis?
An incorrect hypothesis created by Leave that stated DNA contained equal amounts of all 4 nucleotides
Deoxyribose has a _______ atom rather than a __________ _____ at the ___ position
hydrogen; hydroxyl; C-2’
The ___ atom of the sugar is involved in the chemical linkage to the nitrogenous base.
C-1’
If base is purine, ___ atom covalently bonds to sugar.
N-9
A-T base pairs form _ hydrogen bonds
2
C-G base pairs form _ hydrogen bonds
3
If base pyrimidine, the __ atoms bonds to the sugar
N-1
In DNA, the phosphate may be bonded to the __, __, or__ atom of the sugar.
C-2; C-3; C-5
__ phosphate group is most common
C-5’
Nucleotides are called what else?
Nucleoside monophosphate
Describe a phosphodiester bond
A phosphate group linked by two sugars to link two mononucleotides
Each phosphoric acid has been joined by _ _______ by an ____ _______ on both sides.
2 alcohols; ester linkage
Short chains of 20 nucleotides are called?
oligonucleotides
Histones contain large amounts of ________ charged _____ and ______ which makes it possible to bond to negatively charged phosphate groups in nucleotides.
positively; lysine; arginine
Describe chromatin
They are composed of DNA and proteins and undergoes lots of coiling and folding as they condense in the cell nucleus
What happens if histone molecules are chemically removed from the chromatin?
The regularity of diffraction pattern gets disturbed
Chromatin is made up of ___________
nucleosomes
Describe nucleosome core particles
They consist of 147 base pairs and are created when nuclease digestion time is extended. About 200 base pairs are removed from the nucleosome
Describe Linker DNA
DNA lost in the process of creating nucleosome core particles
Linker DNA is associated with histone __.
H1
Describe the formation of nucleosomes
The 1st level of packing where the DNA helix reduces by 1/3 its original length by wrapping around histones
Chromatin is packed into a thicker solid called _______.
solenoid
Describe chromatin remodeling
Chromatin relaxing its compact structure and composing regions of DNA to regulatory proteins to allow replication and gene expression
Nucleotides are linked by a phosphodiester bond between the phosphate group at the ___ position and the __ group on the __ position
C-5’; OH; C-3’
Chromatin is bound up in nucleosomes with which histones?
H2A, H2B, H3, and H4.
___________ is uncoiled and active, whereas ____________ remains condensed and is inactive.
Euchromatin; heterochromatin
