8 Questions
What percentage of chromatin is made up of DNA?
40%
Which component is not a part of a nucleotide?
Lipid
How many hydrogen bonds connect Adenine (A) and Thymine (T)?
Two
What structural unit is formed when DNA winds around histone proteins?
Nucleosome
Approximately how many nucleosomes are present in a single human chromosome?
Millions
During which stage of cell division do chromatin fibers condense into chromosomes?
Prophase
Which nitrogenous base pairs with Cytosine (C)?
Guanine (G)
Which sequence is not correctly matched between the strands of DNA?
A-U
Study Notes
Chromatin
- Chromatin composed of DNA (40%) and histone proteins (60%)
- Histones package and coil DNA into structural units called nucleosomes
Molecular Structure of DNA
- DNA is a macromolecule with a double helical structure
- Composed of two complementary strands wound around each other
- Each strand consists of repeating nucleotides (phosphate, sugar, and nitrogenous base)
- Four types of nitrogenous bases: Adenine (A), Guanine (G), Cytosine (C), and Thymine (T)
- Base pairing: A-T (two hydrogen bonds) and G-C (three hydrogen bonds)
Histones and Nucleosomes
- Histone proteins serve to package and coil DNA into nucleosomes
- A DNA strand winds around a core of eight histone proteins (histone octamer)
- A nucleosome consists of a histone octamer and a DNA strand
- One human chromosome has approximately a million nucleosomes
Cell Division
- Chromatin fibers condense into chromosomes during prophase stage
- Chromosomes are compact structures formed during cell division
This quiz covers the molecular structure of DNA, chromatin composition, and the components of DNA strands. Test your knowledge of cell biology fundamentals!
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