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Bio Chapter 5
Lipids, Membranes, and Cell Components
| Question | Answer |
|---|---|
| In which eukaryotic organelle are various macromolecules broken down and destroyed? - Mitochondria - Golgi Apparautus - Endoplasmic Reticulum - Lysosome | Lysosome |
| Where are the ribosomes that translate proteins to be secreted from the cell? - In the nucleolus - In the cytosol - Attached to the Golgi apparatus - Attached to the rough endoplasmic reticulum | Attached to the rough endoplasmic reticulum |
| An amphipathic molecule is one that: - Has a head and tail domain - Makes up a membrane - Contains both polar and non polar regions - Can fully dissolve in water | Contains both polar and non polar regions |
| What is the major type of lipids that are found in cell membranes? | Phospholipids |
| What are phospholipids made up of? | A glycerol backbone attached to a phosphate group and two fatty acids |
| Why is a phosphate head group of a phospholipid hydrophilic? | Because it is polar, and it has the ability to form hydrogen bonds with water. |
| Why are the two fatty acid tails of a phospholipid hydrophobic? | Because they are non polar, and they also do not form hydrogen bonds with water. |
| What is the definition of amphipathic? | Having both hydrophilic and hydrophobic regions. |
| Celery stalks that are immersed in fresh water for several hours become stiff. Similar stalks left in a 0.15 M salt solution become limp. What does this tell us? | The freshwater is hypotonic and the salt solution is hypertonic to the cells of the celery stalks. |
| ____________ fatty acids and _______________ hydrocarbon chains increase membrane permeability. - Unsaturated; Long - Saturated; Long - Unsaturated; Short - Saturated; Short | Unsaturated; Short |
| What can membranes be made up of? | Lipids, Carbohydrates, and Proteins |
| How does membrane fluidity change as the fatty acid chain length changes? | Longer tails tend to have a lower fluidity, whereas shorter tails have a higher fluidity. |
| How does membrane fluidity change as fatty acid saturation changes? | Unsaturated fatty acids have more fluidity, whereas saturated fatty acids have less fluidity |
| How does membrane fluidity change as temperature changes? | Higher temperatures have more fluidity, whereas lower temperatures have less fluidity. |
| What is the difference between integral and peripheral membrane proteins? | Integral proteins are embedded in the whole phospholipid bilayer (hydrophilic and hydrophobic), and peripheral proteins are located in the inner/outer surface of the bilayer (like a floating iceberg). |
| Predict which way a certain substance will diffuse, given its concentration on either side of a selectively permeable membrane. | From areas of high concentration to low concentration |
| What does hypotonic mean? | When solution inside the membrane has a lower concentration of solutes than the exterior has, water begins to move out of the vesicle into the solution outside. As water leaves, the vesicle shrinks and the membrane shrivels. |
| What does hypertonic mean? | When the solution inside the membrane has a higher concentration than the exterior has, water moves into the vesicle by osmosis. The incoming water causes the vesicle to swell and increase firmness. |
| What does isotonic mean? | If the solute concentrations are equal on both sides of the membrane, there will be no change. |
| What is the definition of diffusion? | The random motion of molecules, with net movement occurring from areas of higher to lower concentration of the molecules. |
| What is facilitated diffusion? | Diffusion through a membrane protein, bypassing the lipid bilayer. |
| What is the definition of osmosis? | The net movement of a solvent, such as water, across a selectively permeable membrane toward the side of higher solute concentration. |
| What is active transport? | - Requires energy (ATP) - Moves molecules against the concentration gradient (low to high) - - Cells move substances through transport proteins embedded in the cell membrane - An example of this is the sodium-potassium pump, exocytosis, and endocytosis |
| Define primary active transport. | Active transport that uses energy directly in this manner |
| What are four ways in which membrane proteins can help substances cross a cell membrane? | Transporter, Receptor, Enzyme, and Anchor |
| What is the function of a transporter for when membrane proteins can help substances cross a cell membrane? | They act as doors to the cell, helping certain molecules pass back and forth across the plasma membrane (active/passive). |
| What is the function of a receptor for when membrane proteins can help substances cross a cell membrane? | They bind to signaling molecules outside the cell and subsequently transmit the signal. |
| What is the function of an enzyme for when membrane proteins can help substances cross a cell membrane? | They act as an active site. |
| What is the function of an anchor for when membrane proteins can help substances cross a cell membrane? | They affect the cells ability to move |
| What are peripheral membrane proteins? | They are on the surface of plasma membranes and are loosely bound to lipid bilayer. They do not interact with the hydrophobic core in between phospholipid bilayers, and are an easy protein dissociation. |
| What are integral membrane proteins? | They occur either fully or partially submerged in the lipid bilayer of a plasma membrane. They are tightly bound and are directly interacting with the hydrophobic core of the plasma membrane. They have a difficult dissociation. |
| What is passive transport? | - This transport in and out of the cells works through diffusion It doesn't require energy (ATP) - Moves molecules with the concentration gradient (high to low) - An example would be simple diffusion, facilitated diffusion, filtration, and osmosis. |
| Define secondary active transport | Active transport that uses the energy of an electrochemical gradient to drive the movement of molecules. |
| What are the two types of membrane transporters? | Channel and carrier |
| What is a channel in terms of a membrane transporter? | It provides an opening between the inside and outside of the cell through which certain molecules can pass, depending on their shape and charge. Some are gated, meaning they open with response to a signal, which may be chemical or electrical. |
| What is a carrier in terms of a membrane transporter? | It binds and then transports specific molecules. It facilitates movement between molecules. |
| What are the membrane bound compartments that make up the endomemraue system? | Nuclear Envelope, Endoplasmic Reticulum, Golgi Apparatus, Vesicle, Plasma Membrane, and Lysosome |
| What is the function of a nuclear envelope? | It surrounds the nucleus with a double membrane with multiple pores. It also separates the contents of the nucleus from the cytoplasm and provides structural framework of the nucleus. |
| What is the function of the endoplasmic reticulum? | It is involved with protein and lipid synthesis. They produce proteins for the rest of the cell to function. |
| What is the function of the Golgi apparatus? | It modifies and sorts proteins and lipids. It functions as a factory in which proteins received from the ER are further processed and sorted for transport to their destinations: lysosomes, plasma membrane, or secretion. |
| What is the function of the vesicle? | They transport and store substances within a cell from one cell to another. They also recycle waste materials. |
| What is the function of the plasma membrane? | It provides protection for the cell from its surroundings. |
| What is the function of the lysosome? | They function as the digestive system of the cell, meaning that they degrade material taken up from outside the cell and digest the compounds of the cell itself. Simply, they degrade molecules. |
| What is the path of the proteins being synthesized in the cell? | Rough ER --> Golgi --> Cytoplasm --> Plasma Membrane (Exocytosis) |
| How does fatty acid tail saturation affect the formation of a lipid? | It affects the tightness of packing. Unsaturated fatty acid tails have a slight curve/bend, and saturated fatty acids appear in a straight formation. |
| Lipid bilayers with short and unsaturated hydrocarbon tails have what? | They have a higher permeability and fluidity |
| Lipid bilayers with long and saturated hydrocarbon tails have what? | They have a lower permeability and fluidity |
| What is homeostasis? | The maintenance of a constant environment |
| What is a solute? | It is a dissolved substance (ex. sugar when mixed with water) |
| What is a solvent? | It is a substance that can dissolve another substance (ex. water when mixed with sugar) |
| What is a solution? | It is a homogenous mixture of one or more solutes dissolved in a solvent. |
| What is the definition of permeability? | The structure tendency to allow a given substance (solute/solvent) to pass across it. |
| Small, non polar molecules have what kind of permeability? | High permeability |
| Small, uncharged polar molecules have what kind of permeability? | Somewhat high permeability |
| Large, uncharged polar molecules have what kind of permeability? | They have a permeability where some are able to cross and some are not. |
| Ions have what kind of permeability? | Low permeability |
| What is the meaning of an equilibrium? | It is the movement in opposite directions at the same rate |
| What is the meaning of concentration? | The number of molecules (or ions) of substance per unit volume of fluid |
| What is the concentration gradient? | The difference in concentration between two adjacent regions. The molecules move from a space of higher concentration to one of a lower concentration. |
| Determine whether these three options are either passive or active: - Channels - Carriers - Pumps | Channels and Carriers are passive. Pumps are considered active. |
| What is the definition of endocytosis? | It is a process in which substances are brought into the cell. |
| What is the definition of exocytosis? | It is a process In which a cell transports molecules out of the cell. |
| What is the function of a nucleus? | It houses the genome and is the site for RNA synthesis. |
| Where does the no signal peptide take place? | Into the cytosol |
| Where does the amino terminal signal peptide take place? | Into the chloroplast and the mitochondrion. |
| Where does the internal signal peptide take place? | Into the nucleus |
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