Biology, 13.03.2021 01:00 LucasOtto

You are involved in an experiment involving fluorescent painting of chromosomes. You observe the following in a nucleus experiencing homologous pairing in metaphase I of meiosis. At appears that four chromosomes have become paired, with each chromosome pairing with two others (centromeres appear as white circles, and the four chromosomes appear in different colors). What is the best explanation of this finding

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Answer from: andrea1704

It seems that a reciprocal translocation is going on.

Explanation:

A translocation occurs when a chromosomal fragment changes its location in the same chromosome from the original to a new one. Or when it leaves the chromosome to re-locate in a new different chromosome.

According to this, there are different types of translocations:

Intrachromosomal translocations: Intra-radial: the change in position occurs in the same arm of the chromosome. For instance, 123.456789 → 123.478569Extra-radial: The change in position occurs from one arm to the other of the same chromosome. For instance, 123.456789 → 15623.4789Extrachromosomal translocations:Transposition: not reciprocal interchange. The fragment leaves a chromosome to re-locate in another chromosome. The other chromosome does not send any fragment to the first one. Reciprocal translocation: There is a reciprocal interchange. A fragment of chromosome A goes to B, and a fragment of chromosome B goes to A.

Reciprocal translocations might be:

Fraternal: the interchange occurs among homologous chromosomesExternal: the interchange occurs among non-homologous chromosomes

Reciprocal translocations are easily recognized during meiosis because an association between four chromosomes can be observed. This association is a quadrivalent structure.

During metaphase 1, the centromeres involved in the quadrivalent originate centromeric co-orientation or disjunction.

Answer from: Quest

what is the aerea shown

explanation:

Answer from: Quest

fertilization, pictured in figure 24.23a is the process in which gametes (an egg and sperm) fuse to form a zygote. the egg and sperm each contain one set of chromosomes. to ensure that the offspring has only one complete diploid set of chromosomes, only one sperm must fuse with one egg. in mammals, the egg is protected by a layer of extracellular matrix consisting mainly of glycoproteins called the zona pellucida. when a sperm binds to the zona pellucida, a series of biochemical events, called the acrosomal reactions, take place. in placental mammals, the acrosome contains digestive enzymes that initiate the degradation of the glycoprotein matrix protecting the egg and allowing the sperm plasma membrane to fuse with the egg plasma membrane, as illustrated in figure 24.23b. the fusion of these two membranes creates an opening through which the sperm nucleus is transferred into the ovum. the nuclear membranes of the egg and sperm break down and the two haploid genomes condense to form a diploid genome.

explanation:

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You are involved in an experiment involving fluorescent painting of chromosomes. You observe the fol...