Answer:
The delivery of the paternal genome to the egg is a primary goal of fertilization. In preparation for this step, the nucleus of the developing spermatozoon undergoes extensive morphological and biochemical transformations during spermatogenesis to yield a tightly compacted sperm nucleus. These modifications are essentially reversed during fertilization. As a result, the incorporated sperm nucleus undergoes many steps in the egg cytoplasm as it develops into a male pronucleus. The sperm nucleus (1) loses its nuclear envelope, (2) undergoes nucleoprotein remodeling, (3) decondenses and increases in size, (4) becomes more spherical, (5) acquires a new nuclear envelope, and (6) becomes functionally competent to synthesize DNA and RNA. These changes are coordinate with meiotic processing of the maternal chromatin, and often result in behaviors asynchronous with the maternal chromatin. For example, in eggs fertilized during meiosis, the sperm nucleus decondenses while the maternal chromatin remains condensed. A model is presented that suggests some reasons why this puzzling behavior exists. Defects in any of the processes attending male pronuclear development often result in infertility. New assisted reproductive technologies have been developed that ensure delivery of the sperm nucleus to the egg cytoplasm so that a healthy embryo is produced. An emerging challenge is to further characterize the molecular mechanisms that control sperm nuclear transformations and link these to causes of human infertility. Further understanding of this basic process promises to revolutionize our understanding of the mystery of the beginning of new life.
Explanation:
The delivery of the paternal genome to the egg is a primary goal of fertilization. In preparation for this step, the nucleus of the developing spermatozoon undergoes extensive morphological and biochemical transformations during spermatogenesis to yield a tightly compacted sperm nucleus. These modifications are essentially reversed during fertilization. As a result, the incorporated sperm nucleus undergoes many steps in the egg cytoplasm as it develops into a male pronucleus.
Answer:
B. generation of rich organic fertilizer.
Explanation:
Compost and fertilizers are different. There is a simple way to distinguish between compost and fertilizers. Compost feeds the soil, and fertilizer feeds the plants. Fertilizer adds to the soil for nutrient supplying purpose to the plants. But compost helps to increase the microbial activities of the soil, which improves the health of the soil.
Answer:
precipitation is when it rains. it occurs last
Explanation:
Answer:
A nerve impulse from one neuron affects the activity of a neighboring neuron at a point of interaction called the: SYNAPSE
Explanation:
A NEURON(or nerve cell) has 3 parts:
1. The dendrites(multiple)
2. The axon
3. The cell body
A SYNAPSE is an area where the dendrites of one neuron communicates with the axon of another neuron.
At the synapse, nerve impulses are transmitted from one neuron to the other. This is possible through substances called NEUROTRANSMITTERS. There is no direct contact between the axon of one neuron and dendrites of another neuron.
