Answer:
Rods are responsible for vision at low light levels (scotopic vision). They do not mediate color vision, and have a low spatial acuity. Cones are active at higher light levels (photopic vision), are capable of color vision and are responsible for high spatial acuity. The central fovea is populated exclusively by cones.
The correct answers are:
- Methylation of histone tails in chromatin can promote condensation of the chromatin.
- DNA is not transcribed when chromatin is packaged tightly in a condensed form.
- Acetylation of histone tails is a reversible process.
- Some forms of chromatin modification can be passed on to future generations of cells.
- Acetylation of histone tails in chromatin allows access to DNA for transcription.
Histone modifications are post-translational modifications of histone protein that can affect gene expression by altering chromatin structure or recruiting histone modifiers.The most common modifications are methylation, phosphorylation, acetylation and ubiquitylation. All of them affect the binding affinity between histones and DNA and thus loosening (gene activation) or tightening (gene repression) the condensed DNA.
Histone methylation is a transfer of methyl group by histone methyltransferases to lysine or arginine amino acid of protein. Effect of methylation depends on the type of protein that is modified. Demethylation is the reverse process.
Histone acetylation is the process of adding of an acetyl group(by histone acetyltransferases) to histone proteins and it can also activate or inhibit the gene expression. Deacetilation is reverse process.
The correct answer is Alcoholic dementia.
Alcohol-related dementia (ARD) is a type of dementia brought on by prolonged, excessive alcohol use, which damages the brain and impairs cognitive function.
Wet brain, sometimes referred to as Wernicke-Korsakoff syndrome, is another type of ARD that is characterized by short-term memory loss and thiamine (vitamin B1) deficiency.
Patients with ARD frequently exhibit both type's symptoms, such as memory loss, apathy, and impaired planning. ARD may coexist with different types of dementia (mixed dementia). Despite being widely accepted, the diagnosis of ARD is only occasionally used because there aren't any clear diagnostic criteria.
Hence, the patients with generalized loss of brain tissue due to direct consumption of alcohol suffers from alcoholic dementia which causes memory loss and many other problems.
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Answer:
Some forms of chromatin modification can be passed on to future generation of cells
Acetylation of histone tails in chromatin allows access to DNA for transcription
DNA is not transcribed when packaged tightly in a condensed form
methylation of histone tails can promote condensation of the chromatin
Explanation:
chromatin modifications that can be passed on includes epigenetic modifications that are heritable changes made to the chromatin structure that does not involve the DNA sequences. Some epigenetic modifications include DNA methylation and Histone modifications. examples of histone modification include acetylation, methylation, phosphorylation, ubiquintylation etc. All these function either in allowing the DNA become more accessible to transcritional factors or vice versa. for exmple, histone tail acetylation encourages unwounding of nucleosomes allowing transcriptional factors to have access to the DNa while histone tails methylation further tightens the nucleosomes promoting condensation of the chromatin.
