Cell Biology Test - 11

Water contributes about 75-85% of the protoplasm of a living cell, It helps the cell by:
(a) Donating H⁺ or OH^- ions for various reactions.
(b) Keeping constant body temperature.
(c) Eliminating waste products through urine and sweat.
(d) Keeping balance of mineral ions inside the body and thus helps in maintaining homeostasis.

Peroxisome is associated with photorespiration. Peroxisome is a kind of microbody. Peroxisome contains a typical enzyme involved in glycolate metabolism and photorespiration.

It states that a lipid bilayer has some embedded proteins and some proteins on the surface.

Oxidative phosphorylation is the process in which ATP is formed as a result of the transfer of electrons from NADH or FADH₂ to O₂ by a series of electron carriers. This process, which takes place in mitochondria, is the major source of ATP in aerobic organisms.
As oxisomes are present in the inner mitochondrial space of the mitochondrion, they are associated with oxidative phosphorylation.

Lysosomes are membrane-bound vesicles that contain hydrolytic enzymes, such as glycosidases, proteases and sulfatases. Lysosomal enzymes are synthesized in the endoplasmic reticulum (ER), are transported to the Golgi apparatus, and are tagged for lysosomes by the addition of mannose-6-phosphate label. They digest excess or worn out organelles, food particles, and engulfed viruses or bacteria. The membrane surrounding a lysosome prevents the digestive enzymes inside from destroying the cell.

Karyopherins are the transporters that mediate the movement of proteins, ribosomal unit and DNA inside and outside the nucleus. Karyopherins act as importins (i.e. helping proteins get into the nucleus) or exportins (i.e. helping proteins get out of the nucleus).

Mammalian red blood cells do not contain nuclei or internal membranes, so they represent a source from which pure plasma membranes can be easily isolated for biochemical analysis.

The head groups of both phosphatidylserine and phosphatidylinositol are negatively charged, so their predominance in the inner layer results in a net negative charge on the cytosolic face of the plasma membrane.

Spitzenkörper is an organelle specific to certain fungi (fungi) and present at the tip of hyphae of which it is an essential element of growth and morphogenesis.

Woronin bodies are derived from peroxisomes. It is a dense core microbody with a unit membrane found near the septae that divide hyphal compartments in filamentous Ascomycota.