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99 Cards in this Set
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What is "amphipathic" ?
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Cell membrane proteins are typically amphipathic, meaning
they have both hydrophoblic (water fearing) and hydrophilic (Water loving) regions.The hydrophobic regions consist of non-polar amino acids that are stable in the hydrophobic interior of the membrane, while the hydrophilic regions are exposed to water and consist primarily of polar, or charged, amino acids. |
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What is "active transport" ?
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When energy is required for substances to cross the membrane the process is called "active transport" (ie. Sodium-Potassium pump): The movement of a substance across a cell membrane against its concentration gradient (from a region of lowconcentration on one side of the membrane to a region ofhigh concentration on the other), mediated by specific transport proteins and requiring an expenditure of energy |
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What is an "electrochemical gradient" ?
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The inside of a cell is negatively charged relative to the outside.
Due to this positively charged ions are attracted to the negatively charged chamber. The 2 factors, the difference in electric charge and the difference in concentration creates an electrochemical gradient, down which the ions flow spontaneously. |
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What are "polar heads" ? |
Cell membranes are complex, two-layered structures made up of phospholipids. Phospholipids are amphipathic, they have both hydrophilic and hydrophobic parts. The hydrophilic part is also called the "polar head", whereas the hydrophobic part is the non-polar tail. |
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What is a "micelle" ? |
Micelles are lipid molecules that arrange themselves in a spherical form in water due to the amphipathic nature of fatty acids, whereby the hydrophilic heads of phospholipids face water molecules and the hydrophobic tails are forced together, away from the water. |
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What is a phospholipid bilayer ? |
Phospholipid bilayer form when 2 sheets of phospholipid molecules align. The hydrophilic heads face the surrounding solution while the hydrophobic heads interact with each other inside the bilayer. |
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what is an ester linkage ?
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An ester linkage is a bond between a hydroxyl group (--OH) and a carboxyl group (--COOH). During the synthesis of a fat, three fatty acid molecules are joined to glycerol by an ester linkage. |
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What are characteristics of the
hydroxyl group? |
hydrophilic
(OH) soluble |
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What are characteristics of
the Carbonyl group? |
Carbon double bonded with oxygen Hydrophilic soluble |
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What are characteristics of the a
Carboxyl group? |
a Carbonyl group and a hydroxyl group
hydrophilic soluble are acids/make something an acid can donate a hydrogen ion |
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What is a polymer?
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a long molecule consisting of many
similar building blocks Carbohydrates (polysaccharides), Fats, Proteins, Nucleic Acids |
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What is a monomer? |
small building block molecules Simple sugars (monosaccharides- gluclose, fructose), fatty acids, amino acids, Nueotides |
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What are the 3 classes of organic molecules that are polymers? |
Carbohydrates Proteins Nucleic acids |
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What is osmosis ? |
* A process by which molecules of a solvent tend to pass through a semipermeable membrane from a less concentrated solution into a more concentrated one, thus equalizing the concentrations on each side of the membrane, forming an equilibrium. * the diffusion of free water across a selectively permeable membrane |
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What is tonicity ? |
* the ability of a solution surrounding a cell to cause that cell to gain or loose water. into or out of a cell by osmosis is know as its tonicity. * A solution's tonicity is related to its osmolarity, which is the total concentration of all solutes in the solution. |
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What is a fatty acid ? |
Fatty acids and isoprene are the key building blocks of lipids. They are primarily hydrophobic and consist of a long (14-20C) hydrocarbon chain tail bonded to a hydrophilic carboxyl (-COOH) functional group. |
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What is glycerol ? |
A three arbon molecule that forms the backbone of fatty acids |
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What is selective permeable? |
The property of a natural, or artificial, membrane that allows passage of some molecules (such as small hydrophobic molecules and small, uncharged polar molecules) but bars passage of other molecules ( such as larger, uncharged molecules, ie. sugar and ions, which have charges) |
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What is a solute? |
Disolved molecules and ions |
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What is hypertonic ? |
Having a higher concentration of solutes and a lower concentration of water than a solution to which it is being compared Has more solute, and less water. Water moves out of cell, cells will shrink |
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What is hypotonic ? |
solute concentrations are lower in the extracellular fluid
less solute relative to what it is being compared to and more water. water diffuses into cells Cells swell |
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What is isotonic ? |
* Having the same concentration of solutes and water as a
solution to which it is being compared * referring to a soultion that, when surrounding a cell, causes no net movement of water into or out of a cell |
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What is a triacylglycerol?
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3 fatty acids joined to glycerol by an ester linkage |
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What are saturated fats? |
They have the maximum number of hydrogen atoms possible and no double bonds ie. butter |
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What are unsaturated fats? |
They have one or more double bonds i.e. safflower oil |
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what are triglycerides ?
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an ester formed from glycerol and three fatty acid groups. Triglycerides are the main constituents of natural fats and oils, and high concentrations in the blood indicate an elevated risk of stroke |
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what are isoprenes ?
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is a common organic compound
Isoprenes are pure hydrocarbons (C,H ONLY) |
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What are neutral fats ? |
Neutral fats are neutral because they
are uncharged and do not contain acidic or basic groups. They are nonpolar and hydrophobic. |
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What is Cholesterol ? |
a lipid that is synthesized
by animal cells to become an essential component of animal cell membranes it that helps membranes retain fluidity |
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What are steroids ? |
steroids are also a lipid-base hormone which have a characteristic
bulky four-ring structure and are VERY hydrophobic, i.e. Cholesterol (A component of animal cell plasma membranes– also a starting point for synthesis of lipid hormones like estrogen) |
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What is a lipid bilayer? |
Phospholipids organized in two layers wherein
their hydrophobic tails are projecting inward while their polar head groups are projecting outward |
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What is a detergent ? |
amphipathic, surface active, molecules with polar (water soluble) and nonpolar hydrophobic) domains. They bind stronglyto hydrophobic molecules or molecular domains to confer water solubility. |
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What is soap ? |
A substance which dissolves in water,
thusforming a lather, and is used as a cleansing agent |
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What is a saturated fatty acid ? |
A form of fatty acid that lacks
unsaturated linkages between carbon atoms. The name accounts for the inability of this fatty acid to absorb any more hydrogen. Saturated fatty acids are commonly found in animal fats. |
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What is an unsaturated fatty acid ? |
A form of fatty acid containing one or more double (or triple)
bonds and therefore can absorb additional hydrogen atoms. Unsaturatted fatty acids may occur in cis or trans configuration. |
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What is a condensation reaction ? |
A chemical reaction in which the joining of two organic
compounds results in the production and release of water, ammonia, simple alcohol, or other molecules |
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What is a dehydration reaction ? |
two molecules are covalently bonded to each other
through a loss of water molecule |
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What is a functional group ? |
a group of atoms within a molecule that
interacts in predictable ways with other molecules |
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What is Glycerol ? |
Glycerol is a small molecule with three hydroxyl (-OH) groups
A colorless, odorless, viscous metabolic intermediate and structural component of the major classes of biological lipids, triglycerides and phosphatidyl phospholipids. |
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What is a hydrocarbon ? |
A compound consisting solely of carbon
and hydrogen atoms. |
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What is hydrolysis ? |
The process of splitting a compound into fragments with the
addition of water; a kind of reaction that is used to break down polymers into simpler units, e.g. starch into glucose (use water to break the covalent bonds that held the monomers together) |
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What is a lipid? |
-Non-polar, contain C, H, O
-fats, cholesterol, phospholipids, steroids -form cell membranes -regulate growth and development -long term energy storage A fatty or waxy organic compound that is readily soluble in nonpolar solvent (e.g. ether), but not in polar solvent (e.g water) |
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What is a macromolecule ? |
A large complex molecule, such as
nucleic acids, proteins, carbohydrates, and lipids, with relatively large molecular weight. |
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What is "nonpolar" ? |
Pertaining to a compound that is nonionic
Examples of nonpolar compounds are fats and oil. Many nonpolar compounds are hydrophobic. They do not readily dissolve in water but they do in a nonpolar solvent. |
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What is oil ? |
OIL : A triglyceride that is liquid at room
temperature. Triglycerides that are solid at room temperature are known as FATS. |
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What are fats ? |
Fats are composed of three fatty acids linked to glycerol.
–Also called triacylglycerols or triglycerides A viscous liquid, or liquefiable substance not miscible with water. A type of fat which is in a liquid form at normal room temperature. |
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Draw the relationship of water with triglycerides•Try it this way first:1.Draw three separate fatty acid chains surrounded by water molecules.2.Now draw the three FA chains together all surrounded by water molecules. Remember: Like dissolves like. Nonpolar triglycerides are NOT like polar water. |
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Explain phospholipid structure and shape ? |
Phospholipids are the most abundant membrane lipids and are amphipathic, possessing both hydrophilic and lipophilic properties. Contain: glycerol, 2 fatty acid tails (hydrophobic), a PO4 group tails, they face each other making this semi-permable |
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Draw phospholipid chemical structure |
• 3C glycerol backbone • Two nonpolar, long-chain fatty acids attached to two of the Cs. Can vary in length. • Phosphate attached to the other C •Some polar head group attached to the phosphate. |
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what is diffusion ? |
* movement of small solute with concentration gradient (high to low) * Materials move down their concentration gradient through the phospholipid bilayer * it has to be a small body (O, or O2) * happens randomly |
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What is facilitated diffusion ? |
Molecules move across the plasma membrane with the help of a carrier molecule. (High to low) the passage of materials is aided both by a concentration gradient and by a TRANSPORT PROTEIN Example: glucose |
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What is endocytosis and exocytosis ? |
endocytosis: Moving into cell (bacteria) exocytosis: Move out of cell |
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What is denaturation ? |
process modifying the molecular structure of a protein. Denaturation involves the breaking of many of the weak linkages, or bonds (e.g., hydrogen bonds) Denatured proteins have a looser, more random structure; most are insoluble. Denaturation can be brought about in various ways—e.g., by heating, by treatment with alkali, acid, urea, or detergents, and by vigorous shaking |
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What is a covalent bond ? |
strongest type of bond two atoms share a electron either equally (non-polar) or unequally (polar) NOT an attraction of opposite charges |
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The primary fuel for cellular respiration is glucose however, your diet is made up of other components such as _____________________ that can be used as cellular fuels. |
lipids and proteins |
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Neurons (cells within the nervous system) contain a high concentration of potassium ions. How could a neuron acquire even more potassium? |
active transport |
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What is the unique property of phospholipids that makes them well suited to forming the cell membrane (phospholipid bilayer)? |
they contain polar and nonpolar regions |
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The difference between diffusion and osmosis is that: |
diffusion moves small substances from high to low concentration while osmosis moves water from high to low concentrations |
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What are the characteristics of an isotonic solution? |
When the concentration of dissolved substances in the solution is the same as the concentration of dissolved substances inside the cell. |
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The ____ portion of the cell membrane functions as a barrier while the ____ portion determines specific functions, including pumps, receptors, adhesion, etc. |
lipid; protein |
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A sample of cells is placed in a salt solution. The cells shrink and the membrane is distorted. Relative to the cell, the solution is probably: |
hypertonic |
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Crossing a membrane by simple diffusion can be distinguished from facilitated diffusion because: |
Simple diffusion is not saturable; facilitated diffusion rates are limited by the number of functional membrane proteins and can be saturated |
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What is in the cell membrane? |
phospholipids, cholesterol, proteins, glycoproteins and glycolipids |
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What is the purpose of phospholipids in the cell membrane? |
basic structure |
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What is the purpose of cholesterol in the cell membrane? |
stabilization; fluidity |
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What is the purpose of proteins in the cell membrane? |
Receptor Proteins (bind to external chemicals in order to regulate processes within the cell) Recognition Proteins (provide a "fingerprint" for the cell , so it can be recognized by other cells) Transport Proteins (provide a passageway for molecules to travel into and out of the cell) Enzymatic Proteins (accelerate intracellular and extracellular reactions on the plasma membrane) |
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The cell membrane is selectively permeable. What does this mean? |
only certain things can cross, mainly depending on size (monomers and gases are considered small and polymers are considered large) |
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What are some characteristics of passive transport? |
• Occurs spontaneously • No energy required (high to low) • Moving with the concentration gradient • Slow • Stops at equilibrium • Examples: O2 CO2 |
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A cell contains 5% glucose, 10% starch, and 5% protein. The solution outside the cell contains 10% glucose, 5% starch, and 20% protein. The only item that can move by diusion will be _____. Water will move _____ the cell due to the _______ solution surrounding the cell. |
glucose; out of; hypertonic |
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What is an electrochemical gradient ? |
The diffusion gradient of an ion, representing a type of potential energy that accounts for both the concentration difference of the ion across a membrane and its tendency to move relative to the membrane potential. |
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What are ion channels ? |
Ions are charged particles such as Na + , H + , K + , Ca 2+ , and Cl - ions have great difficulty passing through the membrane by simple diffusion because cell membranes are composed of hydrophobic phospholipids that oppose the passage of hydrophilic ions. Therefore, an ion as small as a hydrogen ion (H + ) requires a specific portal protein to facilitate its transport through the membrane. Such a protein molecule is called an ion channel. |
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What is a fluid mosaic model ? |
A membrane that is a fluid structure with a "mosaic" of proteins embedded into it. the membrane as a mosaic of protein molecules drifting laterally in a fluid bilayer of phospholipids. |
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What is a transport protein ? |
a transmembrane protein that helps a certain substance, or class of closely related substances, to cross the membrane |
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What is aquaporin ? |
a channel protein in the plasma membrane of a plant, animal or microorganism cell that specifically facilitates osmosis, the diffusion of free water across the membrane, so the water pores allow only water to pass through |
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What is a sodium-potassium pump ? |
a transport protein in the plasma membrane of animal cells that actively transports sodium out of the cell an potassium into the cell |
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What is osmoregulation ? |
regulation of solute concentrations and water balance by a cell or organism |
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What are gated channels ? |
a transmembrane protein channel that opens or closes in response to a particular stimulus |
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What is an integral protein ? |
* Proteins that penetrate the hydrophobic core of the membrane; they have amphipathic properties * a transmembrane protein (integral proteins that span the membrane), with hydrophobic regions that extend into the hydrophobic interior of the membrane, and with hydrophilic regions in contact with the aqueous solution on one, or both sides of the membrane (or lining the channel in the case of a channel protein). |
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What is a peripheral protein ? |
Proteins loosely bound to the surface of a membrane and not embedded in the lipid bilayer; hydrophilic properties allow interaction with membrane |
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What is a glycolipid ? |
a lipid with one or more covalently attached carbohydrates |
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What is a glycoprotein ? |
a protein with one or more covalently attached carbohydrates |
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What are the 3 classes of transport proteins ? |
1. Channel protein 2. Carrier/Transport protein 1. + 2. : PASSIVE transport 3. Pumps: ACTIVE transport. ie. Sodium-potassium pump: uses ATP to facilitate transport of Na + and K+ against their concentration gradients (the chemical gradient would favour the flow of Na+ into the cell and K+ out of the cell) |
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What are the 4 functions of the cell membrane? |
1. enclose cells and defines boundaries to maintain structural and functional integrity 2. maintain essential differences between compartments 3. act as a semi-permeable membrane between cytoplasm and external environment 4. biological membranes (plasma vs. organelle) vary in function, yet have same basic LIPID BILAYER structure |
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Cell membrane, in a nutshell! |
1. barrier (separate/distinct) 2. transport (semi-permeability) |
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Plasma Membrane Structure: What are the 3 lipid components of the plasma cell membrane? |
1. Phospholipid (most prevalent) - amphipathic (both hydrophilic/hydrophobic), with tails (C-H) in a line 2. Cholesterol 3. Glycolipids (minor component) |
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Plasma Membrane Structure: What are the 2 types of membrane proteins? |
1. Integral membrane proteins 2. Peripheral membrane proteins |
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Phospholipids: Phospholipids are _________, meaning the contain BOTH hydrophilic and hydrophobic regions |
amphipathic |
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Membrane Proteins: What are the Various Functions of Membrane proteins? |
1. Transport of ions and polar molecules 2. Binding of hormones (receptors) 3. Signal transduction across membrane 4. structural stability of bilayer 5. give each cell its functional properties |
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Membrane Fluidity (Fluid Mosaic Model): Fluidity is moderated by the membrane's... |
cholesterol content: The cholesterol moderates fluidity - cholesterol INCREASES fluidity of membranes with high saturated fatty acid content - DECREASES fluidity of membranes high in unsaturated fatty acids |
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Protein channels and carrier protein |
Transport protein: a transmembrane protein that helps a certain substance or class of closely related substances to cross the membrane Carrier Protein: |
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What are the 3 major classes of macromolecules in biology? |
1. The Proteins (Peptides or Polypeptides) 2. The Carbohydrates (= the saccharides; macromolecules are specifically the polysaccharides) 3. The Nucleic acids (nucleotides) |
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Upon contact with water phospholipids form either: |
1. Micelles 2. Phospholipid bilayers (lipid bilayers) - heads face the water and tails face each other |
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Why do single tailed phospholipids form micelles? |
*essentially they try to bury their tails. *Polar water molecules cannot form hydrogen bonds with hydrocarbon tails |
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What happens when lipid bilayers in water are agitated by shaking ? |
The layers break and re-form as small, spherical structures called liposomes. |
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Why do double bonds between carbons in a carbon chain reduce the hydrophobic interaction? |
The double bonds in
unsaturated fats cause kinks in the phospholipid tails so that the hydrophobic tails can't interact as strongly, hereby increasing the permeability |
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What is a concentration gradient ? |
A difference in solute concentration creates a concentration gradient. Molecules and ions move randomly when a concentration gradient exists, but there is a NET MOVEMENT from high to low concentration regions. Diffusion is spontaneous. |
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What is osmosis ? |
Water moves quickly across lipid bilayers from regions of high to low water concentration via osmosis, a special case of diffusion. Osmosis can only occur across a selectively permeable membrane. |
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What is "FRAP" ? |
Fluorescence recovery after photobleaching |
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Explain: Passive/ Facilitated/ Active transport ? |
1. Passive: only concentration gradient drives diffusion process - down gradient only, i.e. osmosis 2. Facilitated: passive transport mediated by a membrane protein 3. Active: energy input allows transport proteins to move counter-gradient |
