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Osmosis - water transport

By: HWC, Views: 6742

Osmosis is the flow of water down its concentration gradient, across a semi-permeable membrane. Osmosis is an example of diffusion, which is when molecules tend to distribute themselves evenly in a space. what is a semi-permeable membrane? It is a membrane or barrier that allows some molec...

Complement Proteins Animation

By: HWC, Views: 3477

Formation of membrane attack complexes. Complement proteins can activate when they bind to antibodies that are bound to a pathogen. Complement proteins also activate when they bind directly to bacterial surfaces. Cascading reactions yield huge numbers of different types of complement protei...

Conduction of action potentials

By: HWC, Views: 6780

• Action potentials must be rapidly conducted over long distances in order for the nervous system to communicate with other cells. • Propagation of an action potential uses processes similar to those that generate the potential at the trigger zone. • a When a graded potential reaches ...

Phases of an Action Potential - Resting Potential, Threshold, Rising, Falling, & Recovery Phases

By: HWC, Views: 6103

In this tutorial, we will review the phases of an action potential measured from a small area of a neuron's membrane. The action potential can be divided into five phases: the resting potential, threshold, the rising phase, the falling phase, and the recovery phase. When the neuron is at rest,...

Endocytosis -Types and Phagocytosis

By: HWC, Views: 6686

Endocytosis is the process by which a substance is brought inside a cell without having to pass through the cell membrane. It is the opposite of endocytosis, the process by which substances exit the cell without having to pass through the cell membrane. Exocytosis – membrane-enclosed secret...

Action potentials - electrical characteristics and generation

By: HWC, Views: 6583

• 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...

Second Messengers in the Inositol-lipid Signaling Pathway

By: HWC, Views: 5893

Extracellular signals produce specific responses in target cells through the action of intracellular second messengers. Here, we focus on three second messengers, IP3, DAG, and Ca2+, all involved in the inositol-lipid signaling pathway. A hormone-receptor signal on the cell surface leads to the a...

ATPase function - membrane transport, contractile proteins and synthesis

By: HWC, Views: 7048

• Energy from ATP is used to move ions across the cell membrane during active transport. • This membrane protein transports sodium out of the cell and potassium into the cell. As such, it is called a sodium-potassium pump. • Because this pump also acts as an enzyme to hydrolyze ATP it i...

Mitochondrial Structure & ETC Protein Complexes (Protein Complexes and Electron Transport)

By: HWC, Views: 6253

The energy carrying molecules, NADH and FADH2, that were generated in glycolysis and the Krebs cycle, now are processed in the mitochondria where their high energy electrons are deposited in an electron chain complex located in the inner mitochondrial membranes. These high-energy electrons now dr...