Double fertilization is a complex fertilization mechanism of flowering plants. This process involves the joining of a female gametophyte with two male gametes. It begins when a pollen grain adheres to the stigma of the carpel, the female reproductive structure of a flower.
Answer:
The Z lines and H- zone shortens during the muscle contraction.
Explanation:
Sarcomere is the area between the two Z lines. The Z- lines are present in the centre of I - band and H - zone is present in the A - band. The actin filaments which are thin filaments present in I- band and contracts, slide over the myosin filament during contraction.
The I - band, H- zones are became shortens as they are thin than the A- band. It is anisotropic band having thick myosin filaments. They are not flexible and remain in its constant shape during the muscle contraction.
After the muscle contraction, the A- band and the H- zone comes to their original shape. In other words, the sarcomere shortens and comes back during muscle contraction, and relaxation.
Answer:
sexual reproduction between two individuals from different continents
Answer:
The correct answer is A) Histone deacetylation generally decreases gene expression.
Explanation:
Histones are the proteins that are responsible for the condensation of chromatin, which is directly linked to the capacity that a gene has to be expressed. The more condensed a gene is, the less expressible it becomes.
In order to regulate the gene expression, histones can suffer from many modifications that can change their conformation and the expressiveness of specific genes.
<u>Histone acetylation is linked with an increase of gene expression; while deacetylation and methylation decrease gene expression.</u>
