Biology Test - 72

Lampbrush chromosomes (LBCs) are transcriptionally active chromosomes found in the germinal vesicle (GV) of large oocytes of many vertebrate and invertebrate animals and also in the giant single-celled alga Acetabularia. These cells are all in prophase of the first meiotic division.

Hofmeister was an early student of the genetics in plants. He is cited for the first studies of plant embryology. According to C. D. Darlington, Hofmeister had observed what would later be called chromosomes in a dividing cell nucleus as early as 1848.

In eukaryotes, a centromere is a region of DNA that is responsible for the movement of the replicated chromosomes into the two daughter cells during mitosis and meiosis. There is one centromere on each chromosome, and centromeres are responsible for two major functions.

Autosomes are homologous chromosomes i.e. chromosomes which contain the same genes (regions of DNA) in the same order along their chromosomal arms. The chromosomes of the 23rd pair are called allosomes consisting of two X chromosomes in most females, and an X chromosome and a Y chromosome in most males.

DNA replication occurs in S-phase. In a cell cycle the condensation of chromosome with visible centromere occurs during M-phase. Sequence in cell cycle is G₁, S, G_2, M.

Lampbrush chromosomes (LBCs) are transcriptionally active chromosomes found in the germinal vesicle (GV) of large oocytes of many vertebrate and invertebrate animals and also in the giant single-celled alga Acetabularia. These cells are all in prophase of the first meiotic division.

An abacus is an instrument for performing calculations by sliding counters along rods or in grooves.

albino;a person with pale skin, light hair, pinkish eyes, and visual abnormalities resulting from a hereditary inability to produce the pigment melanin.

Humans have a characteristic diploid chromosome number of 2N=46 whereas the other Great Apes (orangutans, gorillas, and chimps) are all 2N=48. The large metacentric Chromosome 2 of Homo appears to be the result of a fusion between two smaller telocentric chromosomes found in the other Great Apes.

Chromosome banding refers to alternating light and dark regions along the length of a chromosome, produced after staining with a dye. A band is defined as the part of a chromosome that is clearly distinguishable from its adjacent segments by appearing darker or lighter with the use of one or more banding techniques.