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:
Number of Squirrels Entering and Leaving a Population after 1 Year Cause of change Number of squirrels Died from predation 2 Born 4 Immigration 10 Left to find food 3 Died from disease 8 Left to find a mate 3 Population growth is decreasing.
Explanation:
Answer:
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Explanation:
1/4 : 25%
3/4 : 75%
4/4 : 100%
2/4 : 50%
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Answer:
A chemical bond occurs as a result of electrostatic interaction between the nuclei and the electrons of the joining atoms. ... Simultaneously, a repulsion arises between the two positively charged nuclei and the same occurs with the electrons of the two negatively charged atoms.
Explanation:
p o n l o e n e l t r a d u c t o r
Answer:
Since, the original DNA sequence has not been provided, the mutation can be an insertion/deletion or a frameshift mutation.
- Mutated DNA
- Frameshift mutation/ insertion or deletion
- All the amino acids changed after the point mutation
Explanation:
Frameshift Mutation:
- A frameshift mutation is the alteration in the reading frame of the DNA due to the addition/deletion of one or two nucleotides.
- This type of mutation moves the mRNA sequence one or two bases forwards or backwards which disrupts the three base codons sequence required for translation into proteins.
- The CT at the end of the sequence is indicative of a frameshift in the DNA reading frame.
- Frameshift mutation affect all amino acids in a polypeptide chain as all codons are moved one or two steps forwards or backwards.
