Search Results

Cellular defenses (natural killer cells, phagocyte types & process of phagocytosis)

By: HWC, Views: 7459

• Lymphocytes that rapidly defend against abnormal (cancer) or virus-infected cells. • Found in blood, spleen, lymph nodes, and red bone marrow. • Lack receptors for binding with specific antigens. • Act upon cells displaying abnormal MHC antigens. • NK cells destroy cells in ...

Hormones and the menstrual cycle Animation

By: HWC, Views: 4648

Feedback loops to the hypothalamus and pituitary gland from the ovaries during the menstrual cycle Animation for a step-by-step explanation. Production of a releasing hormone (GnRH) by the hypothalamus prods the pituitary's anterior lobe to release FSH and LH. In the ovary, FSH and LH stimula...

T cell receptors

By: HWC, Views: 7401

• T cells are responsible for cell-mediated immunity. • Each T cell contains a unique form of T cell receptor (TCR) on its membrane. • These T cell receptors are produced through a process of genetic recombination which is able to produce millions of different variations. • Each T ce...

Mechanics of Sound Animation

By: Administrator, Views: 10972

Process of Hearing Sound waves are directed to the eardrum, causing it to vibrate. These vibrations move the three small bones of the middle ear (malleus, incus, and stapes). Movement of stapes at oval window sets up pressure waves in the perilymph and endolymph. Process of Hearing The wav...

Properties of macromolecules (Explained with No Audio)

By: HWC, Views: 6677

The term thermoplast refers to a plastic, which when heated is soft and deformable, but which rehardens when cooled. The molecular structure of the macromolecules is comparable to a cotton ball in which the individual fibers of the macromolecules are shown. The fibers of the cotton ball can s...

Secondary Active Transport

By: HWC, Views: 8261

Energy stored (in a hydrogen or sodium concentration gradient) is used to drive other substances against their own concentration gradients Secondary active transport, is transport of molecules across the cell membrane utilizing energy in other forms than ATP. In many cells, antiporters mov...

Simple Diffusion - Ion transport

By: HWC, Views: 7744

In the process of diffusion, a substance tends to move from an area of high concentration to an area of low concentration until its concentration becomes equal throughout a space. Ions must diffuse through membrane pores or gated channels. Pores are always open. More pores allow more ions...

Peptide Bond Formation Animation

By: HWC, Views: 1545

During protein synthesis, peptide bonds link amino acids together in the order specified by DNA instructions. In this case, the first two amino acids in the protein are methionine and alanine. Here are ball-and-stick models of these amino acids. Peptide bond formation is a type of condensatio...

Hydrogen bonds vs. Ionic bond

By: HWC, Views: 6508

The slight positive charge of a hydrogen atom in a water molecule can attract an atom with a slight negative charge, such as the nitrogen in a molecule of ammonia. This forms a hydrogen bond between the two atoms. Hydrogen bonds join the two strands of a DNA molecule. Although hydrogen bo...