<span>Cytokinesis is when the cytoplasm divides into two daughter cells.
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Answer: This is because a parent with type AB blood has both A and B antigens therefore, the child must inherit either A or B antigen from the parent.
Explanation: In ABO blood type, blood types are classified on the basis of the antigens present in the red blood cells. There are two types of antigens: A and B antigens.
A blood type is so named because it has A antigens, B blood type has B antigens, AB blood type has both A and B antigens while O blood type has no antigens.
Each of these blood types is controlled by two alleles, and children inherit one allele from each parent. If a parent has AB blood type, none of his offsprings will have O blood type because each offspring must inherit either antigen A or B from this parent.
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: The speed of sound is faster in the water than in the air.
The speed of sound is different between those two mediums because they have different densities. Since, water is denser than air, more energy is required to generate a wave but once it stars, it travels faster than it would do in air. Sound waves’ travel can be presented by particles that transmit the energy one to another as they bump. The sound speed is lower in the air (than in water) because particles are far apart, so they travel further before they collide.
