30 Questions
What are the four types of core histone proteins found in a nucleosome?
H2A, H2B, H3, H4
How many histone proteins make up the core of a nucleosome?
8
Which part of the nucleosome structure consists of DNA wrapped around a core of histone proteins?
Histone Core
Where are nucleosomes particularly abundant in the eukaryotic genome?
Heterochromatic regions
In approximately how many turns is the DNA double helix wound around the histone octamer in a nucleosome?
~1.65 turns
What is the term that refers to the entire nucleosome structure including the core histones and the linker DNA segments?
Nucleosome Unit
What is the most common ploidy in eukaryotic species?
2n
Why is polyploidy rare in animals?
Lethal in animals
Which organisms are more likely to exhibit polyploidy?
Plants and invertebrates
How many chromosomes could be found in an allotriploid with species A having 2n = 20 and species B having 2n = 24?
34 or 32
Why do some individuals mistakenly assume that a triploid has three times as many chromosomes as a normal individual?
Misunderstanding of basic genetics principles
How is autotriploid chromosome number calculated?
(2n) * 3
What would be the expected pattern of DNA density distribution in the Meselson-Stahl experiment if dispersive replication were correct?
A gradual shift towards lighter densities with each successive round of replication.
Why would dispersive replication result in a diffuse band or smear on the density gradient in the Meselson-Stahl experiment?
Due to the fragmentation of parental DNA strands into smaller pieces.
How does rolling circle replication compare to theta replication in terms of speed?
Rolling circle replication is typically faster for the same genome size and replication speed.
In dispersive replication, what happens to the proportion of newly synthesized DNA with each round of replication?
It increases relative to parental DNA.
What would the distribution of DNA densities reflect over successive rounds of dispersive replication?
The mixing of parental and newly synthesized DNA fragments.
Why would rolling circle replication be faster than theta replication for the same genome size?
Due to the continuous synthesis of new DNA strands ahead of the replication fork.
What is the main difference between theta replication and rolling circle replication?
Theta replication involves bidirectional DNA synthesis while rolling circle replication involves unidirectional synthesis.
Which statement best describes the process of theta replication?
The DNA opens at the origin of replication and new strands are synthesized simultaneously at each fork.
What are the main components of a nucleosome?
Histone Proteins: H2A, H2B, H3, H4
How does the replication speed of rolling circle replication compare to theta replication?
Rolling circle replication is generally faster than theta replication.
What role do histone proteins play in a nucleosome?
Histone proteins are the components around which DNA wraps to form a nucleosome.
Why does rolling circle replication tend to proceed more rapidly than theta replication?
Because rolling circle replication does not require coordination of multiple forks, making it simpler and continuous.
What is the main difference between euchromatin and heterochromatin?
Euchromatin is transcriptionally active, while heterochromatin is transcriptionally inactive.
How does nucleosome structure contribute to the packaging of DNA?
Nucleosomes consist of DNA wrapped around a core of histone proteins, organizing long DNA strands.
In which part of the nucleus is heterochromatin typically found?
At the periphery of the nucleus
What contributes to the dynamic change between euchromatin and heterochromatin during the cell cycle?
Modifications to histone proteins and DNA methylation
Why are genes within heterochromatic regions typically silenced or expressed at lower levels?
" Due to the condensed nature and transcriptional inactivity of heterochromatin
What role do nucleosomes play in chromosome organization?
" Nucleosomes are involved in packaging and organizing long DNA strands
Learn about the core histones (H2A, H2B, H3, and H4) and how DNA is wrapped around them to form nucleosomes. Explore the role of nucleosomes in compacting and organizing DNA in eukaryotic cells.
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