plasma membrane of a cell is extremely important to the transportation of substances into and out of the cell. The outer membrane of a cell is made up of lipids and proteins. Most of the lipids in plasma membranes are phospholipids. The phospholipids have a hydrophilic head and two hydrophobic tails. When engulfed in water‚ they arrange themselves such that all the hydrophobic tails clump together‚ surrounded by the hydrophilic heads‚ protecting the tails from the exposure to the water. In cells‚ which
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passive transport as energy does not need to be generated. Diffusion is complete when the concentration of molecules is equal on either side of the membrane. Diffusion rate can be influenced by many factors such as: Concentration gradient across the the membrane. Permeability of the membrane to the diffusing substance. Temperature. Surface area of the membrane. Question 2 2.1 Acetylcholine is an organic chemical that functions in the brain and body as a neurotransmitter it is an ester of acetic acid
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Bacteria Bacteria are microscopic organisms whose single cells have neither a membrane-enclosed nucleus nor other membrane-enclosed organelles like mitochondria and chloroplasts. Another group of microbes‚ the archaea‚ meet these criteria but are very different from the bacteria in other ways. In fact‚ there is considerable evidence that you are more closely related to the archaea than they are to the bacteria! Bacteria are living things that are neither plants nor animals‚ but belong to a group
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have a huge impact on the communication between cells. Cell communication is a crucial process necessary for cells to carry out various functions. Drugs such as Methylenedioxymethamphetamine (MDMA)‚ known as ecstasy‚ can create barriers or confusion to cells. Cell to cell communication carry messages from signaling cells to target cells. Usually a cell will bind with a target cell through a receptor protein in the plasma membrane of the target cell
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Institute www.ilri.org ILRI Better lives through livestock Fodder beet (Beta vulgaris) for livestock feed Objective on small-scale farms To provide palatable and high energy feed for livestock with nutritive value similar to cereal grains Description • Fodder beet is a biennial plant with thick roots and is cultivated in a cooler climate • The roots are a rich energy source for livestock • Fodder beet needs a long growing season‚ 6–7 months and is grown in the highlands (1800–3000
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Bacterial Energetics and Membranes Abstract The Mg2+/Ca2+ ATP synthase present in all bacterial membranes‚ particularly E. coli‚ couples ATP synthesis to the proton (H+) gradient produced by the ETC‚ a process known as oxidative phosphorylation. The gradient acts to power the ATPase‚ so that it may phosphorylate ADP to produce ATP. The reverse reaction of this process‚ or hydrolysis of ATP into ADP and Pi‚ may be used to observe ATPase activity when the resulting Pi is quantitatively measured
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Cells‚ Cell Division‚ and Cell Specialization Fundamentally Different Types of Cell Prokaryotic Cell- single celled: only DNA+ structure (“before nucleus”) E.g. zygote-complete DNA Eukaryotic Cell-multi-celled (“after nucleus”) Prokaryotes Eukaryotes DNA In “nucleoid” region Within membrane-bound nucleus Chromosomes Single‚ circular Multiple‚ linear Organelles None Membrane-bound organelles Size Usually smaller Usually larger- 50 times Organization Usually single-celled Often multicellular
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The Effect of Salt Concentration on Osmosis in Potato Cells We should first explain what Osmosis is. It’s a passage of water from a region of high water concentration through membrane to a region of low water. Semi membrane is a very thin layer of material‚ which allows some things to pass through them but prevent other things from passing through. The cells allow small molecules like Oxygen‚ water‚ Carbon Dioxide‚ Ammonia. But will not allow larger molecules like Sucrose‚ Starch‚ or protein‚ etc
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Resting membrane potentials Definition: Large nerve fibers when not transmitting nerve signals is about 90 millivolt. That is‚ the potential inside the fiber is 90 millivolts more negative than the potential in the extracellular fluid on the outside of the fiber. The Na+-k+ pump also causes large concentration gradients for sodium and potassium across the resting nerve membrane. These gradients are the following: Sodium ( outside): 142 mEq/L Sodium ( inside): 14 mEq/L Potassium ( outside):
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1 Experiment Membrane Transport Objectives ► Referring to energy‚ what two ways can substances enter a cell? What is active transport? What is passive transport? How is osmosis related to diffusion? How can we demonstrate active transport? How can we demonstrate Brownian movement? How can we demonstrate diffusion (2 ways)? How can we demonstrate osmosis (3 ways)? In terms of relationships between substances‚ how can we define “hypertonic”‚ “isotonic”‚ and “hypotonic”? What is the relationship
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