Questions

All of the genetic information in a cell was initially thought to be confined to the DNA in the chromosomes of the cell nucleus.

It is now known that small circular chromosomes, called extranuclear, or cytoplasmic, DNA, are located in two types of organelles found in the cytoplasm of the cell.

These organelles are the mitochondria in animal and plant cells and the chloroplasts in plant cells.

Chloroplast DNA (cpDNA) contains genes that are involved with aspects of photosynthesis and with components of the special protein-synthesizing apparatus that is active within the organelle.

Mitochondrial DNA (mtDNA) contains some of the genes that participate in the conversion of the energy of chemical bonds into the energy currency of the cell—a chemical called adenosine triphosphate (ATP)—as well as genes for mitochondrial protein synthesis.

Fertilization is the process in which a single haploid sperm fuses with a single haploid egg fuse to form a zygote.  

An animal zygote under go mitosis and divides to form a hallow ball of cells called blastula.

Amino acids are organic compounds containing amine (-NH2) and carboxyl (-COOH) functional groups, along with a side chain (R group) specific to each amino acid.

Depending on the nature of the side chain groups, three classes of aminoacids can e distinguished:

1. Amino acids with H ond donor and acceptor groups.

Histidine, lysine, aspartic acid, threonine,...

2. Amino acids with donor grups only.

Arginine, tryptophan and cysteine.

3. Amino acids with acceptor groups only.

Asparagine and glutamine.