Which are the special proteins in muscles that contract and relax to cause movement?

 

Parvovirus B19 causes severe anemia because it preferentially infects erythrocyte precursors.

a. Parvovirus B19 binds preferentially to the erythrocyte blood group P antigen on erythroid precursor cells.

Answers B, C, D are incorrect:

b. after entry the single-stranded viral DNA genome is transported to the cell nucleus where the host DNA polymerase synthesizes the complimentary DNA strand.

c. Parvovirus B19 infection can be diagnosed by direct detection of viral DNA not RNA.

d. the fetus of a seropositive mother is protected from infection by maternal circulating antibodies.

Bile contains bile acids, which are critical for digestion and absorption of fats in the small intestine. Since bile increases the absorption of fats, it is an important part of the absorption of the fat-soluble substances, such as the vitamins A, D, E, and K. Besides its digestive function, many waste products, including bilirubin, a byproduct of red blood cells recycled by the liver are eliminated from the body by secretion into bile and elimination in feces.

The building blocks of the nucleic acids are "Nucleotides".

Each nucleotide are composed of three parts. They are ::

1.Pentose sugar

2.Nitrogenous bases

3.Phosphoric acid.

The genome of an organism is inscribed in DNA, or in some viruses RNA. The portion of the genome that codes for a protein or an RNA is referred to as a gene. Those genes that code for proteins are composed of tri-nucleotide units called codons, each coding for a single amino acid.

During most of the cell cycle, interphase, the chromosomes are somewhat less condensed and are not visible as individual objects under the light microscope. However during cell division, mitosis, the chromosomes become highly condensed and are then visible as dark distinct bodies within the nuclei of cells. The chromosomes are most easily seen and identified at the metaphase stage of cell division and most of the chromosome images in this gallery are pictures of metaphase chromomosomes.

The cell division takes place in mitosis stage.

Unlike Mitosis, Meiosis results in the formation of 4 Genetically different cells.

Meiosis results in the formation of 4 Haploid daughter cells from one Diploid parent cell.