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Simple Diffusion - Ion transport

By: HWC, Views: 7770

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...

Brief Summary on Photosynthesis - Animation

By: HWC, Views: 6739

Can increase its weight by 150 pounds as it grows. Where does the new tissue come from? From the soil? From water? Or possibly from the air? The amazing truth is that new material. comes from an invisible gas in the air. In the process of photosynthesis, plants capture carbon dioxide ga...

Anatomy and Chemical Makeup of a Single Hair (Animation)

By: HWC, Views: 5943

The hair's outer cuticle surrounds hair cells filled with tough keratin macrofibrils. Each macrofibril consists of smaller microfibrils. A microfibril is made up of three keratin polypeptide chains. The chains are linked together by disulfide bonds. A hair consists of keratin chains held...

Protein catabolism (Krebs cycle) and Protein anabolism (protein synthesis)

By: HWC, Views: 8196

• Deaminated acids are brought into the Krebs cycle to be oxidized to CO2 and H2O. • Before entering the Krebs cycle, the deaminated acids are converted into intermediate products (pyruvic acid, acetyl coenzyme A, carbonic acids). • In the Krebs cycle, amino acids are oxidized to form r...

Exocytosis - secretion

By: HWC, Views: 7767

Exocytosis is another method of vesicular transport that moves large volumes Of fluid or chemicals out of the cell. It is a process by which a cell transports secretory products through the cytoplasm to the plasma membrane. A examples of cellular secretory products: 1. Secreted protein - enzym...

Primary and secondary response to infection

By: HWC, Views: 7489

• Pathogens enter the body by penetrating the non-specific barriers in the skin and mucus membranes. • Pathogens first encounter macrophages and natural killer cells that carry out phagocytosis and cytolysis respectively. • A pathogen's first encounter with the immune system can promo...

Digestive chemicals - water, gastric acid, bile & bicarbonate

By: HWC, Views: 7449

• Water is the most abundant molecule in ingested fluids. • Water plays a primary role in hydrolytic digestive reactions. • Helps liquefy and transport digestive foodstuffs down the tract. • Transports secretions from accessory digestive organs to gastrointestinal tract. • Aids ...

Natural Selection, Species Isolation and Real World Example

By: HWC, Views: 7176

`Natural selection' is the process in which organisms with adaptive traits survive and breed in greater number than organisms without such traits. Eventually, almost all of the individuals in the population will have the same adaptive trait. This was the concept presented by Charles Darwin in ...

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

By: HWC, Views: 7479

• 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 ...