Search Results

Activation Energy - Valence Electrons

By: HWC, Views: 7185

■ Shared electrons in the outermost orbital form bonds. These electrons are called valence electrons. ■ Valence electrons are disrupted and can be rearranged into a new bond. ■ The energy necessary to start a reaction and break bonds is called the activation energy. ■ Reactants have...

Helper T cell receptors, activation, proliferation, differentiation & action

By: HWC, Views: 7811

• Most cells which have CD4 on their surface become Helper T cells (TN cells). • The CD4 1 cells only recognize a foreign antigen when it is presented with an antigen presenting immune cell (APC) that includes MHC-II protein. • The Helper T cell antigen receptor must match the presented...

Cytotoxic T cell receptors, activation, proliferation, differentiation & action

By: HWC, Views: 8030

• Most cells which have CD8 on their surface become cytotoxic T cells (Tc cells). • CD8 T cells recognize a foreign antigen when it is presented in conjunction with the protein, MHC-I. • Nearly all nucleated cells in the body express MHC-I molecules. • T cells that recognize self-pe...

B cells and antibodies

By: HWC, Views: 8513

What Are Antibodies? Antibodies, also known as immunoglobulins, are Y-shaped proteins that are produced by the immune system to help stop intruders from harming the body. When an intruder enters the body, the immune system springs into action. These invaders, which are called antigens, can be vi...

The 4 steps of translation Animation

By: HWC, Views: 3547

Translation is the process of formation of a polypeptide chain according to codon present in mRNA. The four steps of translation are: Activation or charging of tRNA Initiation – recognition of start codon, binding of ribosomal subunits to mRNA and formation of initiation complex with Met-tR...

Action potentials - electrical characteristics and generation

By: HWC, Views: 7568

• An action potential is the nervous impulse or signal for long distance communication. Each action potential is generated at the cell's trigger zone. • Action potentials are considered an all-or-nothing phenomena because they are either generated or not. • The generation of an action...

Enzyme-Catalyzed Reactions

By: HWC, Views: 7180

S P Substrate in great excess ([S] -- [E]) (More correctly [S] -- KM, but more on this later) Zero order rate equation: v = k where k is the zero-order rate constant (with respect to substrate). (More correctly [S] -- KM, but more on this later) Substrate forms complex with enzyme. ...

Role of complement proteins

By: HWC, Views: 7473

• Non-specific and specific defense mechanisms work through the functions of complement proteins. • As soon as pathogens penetrate the physical barrier of the skin, other resistance mechanisms begin. • Cells, such as macrophages, phagocytize pathogens. • These cells increase exposu...

Haustral churning, Gastrocolic reflex and mass peristalsis & Defecation

By: HWC, Views: 7900

• As the cecum becomes filled and distends, a local reflex causes: • Closure of the ileocecal valve. • Activation of haustral churning. • Haustral churning mixes the chyme, which helps absorption of water, salts, and vitamins. • Haustral churning propels the contents of the colo...