What is the difference between southern and northern hybridizations?
a. southern blots hybridize a dna probe to a digested dna sample but northern blots hybridize a dna probe to, usually, mrna
b. southern blots use an rna probe to hybridize to dna but northern blots use an rna probe to hybridize to rna
c. southern blots determine if a particular gene is being expressed but northern blots determina the homology between mrna and a dna probe
d. southern blots determine the homology between mrna and a dna probe but northern blots determine if a particular gene is being expressed
e. southern and northern blots are essentially the same technique performed in different hemispheres of the world.

a. southern blots hybridize a DNA probe to a digested DNA sample but northern blots hybridize a DNA probe to, usually, mRNA

Explanation:

Both techniques are quite similar. The main objective of this technique is to identified specific either DNA or mRNA molecules. Hybridization is the process of forming a double - stranded DNA molecule between a single-stranded DNA probe and a single-stranded target DNA (which is the fragment that wants to be found.  Northern blotting targets mRNA while Southern blotting targets DNA sequences.  

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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