Eukaryotes regulation Flashcards
Why is DNA compacted in eukaryotic cells?
To prevent tangling and store genetic information efficiently.
How much DNA is in each human cell?
Approximately 2 meters.
What proteins help in DNA packaging?
Histone proteins.
What is a nucleosome?
The basic unit of DNA packaging.
How are nucleosomes formed?
By wrapping DNA around histone proteins.
What happens to nucleosomes after their formation?
They are compacted into higher-order structures.
Are chromosomes randomly arranged in the nucleus?
No, they are arranged in specific patterns.
Which chromosomes form a cluster in mouse lymphocytes?
Chromosomes 12, 14, and 15.
Why is chromosome organization important?
It is crucial for gene regulation.
What are epigenetic mechanisms?
Chemical changes in chromatin affecting DNA accessibility.
How do epigenetic mechanisms control gene expression?
By altering nucleosome spacing and chromatin structure.
Name a common type of epigenetic modification.
DNA methylation.
What is DNA methylation?
Addition of a methyl group to cytosine residues in CpG sites.
How does DNA methylation affect gene expression?
It represses gene expression by increasing DNA packaging.
What is histone acetylation?
Addition of acetyl groups to histones.
How does histone acetylation affect gene expression?
It activates gene expression by opening DNA fibers.
What are miRNAs?
Small RNA molecules that bind to mRNAs to regulate gene expression.
How do miRNAs affect gene expression?
They negatively control gene expression.
What are lncRNAs?
Long non-coding RNAs that regulate gene expression.
At what levels do lncRNAs regulate gene expression?
Transcriptional and post-transcriptional levels.
What are ribozymes?
RNA molecules with catalytic activity.
How can ribozymes regulate gene expression?
By targeting specific mRNAs to reduce their levels.
Provide an example of a ribozyme’s therapeutic application.
A ribozyme targeting βS mRNA reduces βS mRNA levels in sickle cell anemia.
What affects DNA accessibility in chromatin?
Nucleosome spacing and epigenetic modifications.
What does chromatin structure determine?
Whether a gene is accessible for transcription.
What happens when DNA is tightly packed?
Gene expression is repressed.
What happens when DNA fibers are open?
Gene expression is activated.
What is the role of regulatory RNAs in gene regulation?
They influence gene expression through interactions with DNA and RNA.
Why is packaging DNA efficiently necessary?
To fit 2 meters of DNA into a cell nucleus and regulate gene activity.
How does the nucleus ensure efficient storage?
By organizing chromosomes and modifying chromatin.
