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Biology Chapter 5
Biology Chapter 5 Questions
| Question | Answer |
|---|---|
| What is the difference between a phospholipid and a triglyceride? | A trygliceride is a glycerol attached to 3 fatty acids while a phospholipid is only attached to 2 fatty acids. |
| What makes up a phospholipid molecule? | It is one glycerol attached to a saturated fat, an unsaturated fat, an OH molecule, and a phosphate molecule. The OH molecule forms a covalent bond with a phosphate molecule. The phosphate molecue is then attached to a choline. |
| Why is a phospholipid molecule ideal for making cellular membranes as opposed to a saturated or unsaturated triglyceride? | Because they are made of both saturated and unsaturated fatty acids, therefore making the cell membrane dense enough and solid enough to give shape fluid enough to allow molecule movement. |
| Why is the head of a phospholipid molecule hydrophilic? Why are the tails hydrophobic? | The head is both polar and ionic, which makes it hydrophilic in nature. The tails are made of hydrocarbon chains, which are nonpolar. Nonpolar groups are hydrophobic in nature. |
| What is the main molecule that makes up all biological membranes? | Phopsholipids |
| How do unsaturated fatty acid molecules behave at room temperature? | They are liquid at room temperature. |
| How do saturated fatty acid molecules behave at room temperature? | They are solid at room temperature? |
| Biological membranes are made of what three main macromoleucles? | Lipids, proteins, and carbohydrates. |
| What is a plasma membrane made up of? | A double layer of phospholipid molecules. |
| How do molecules in a plasma membrane typically move? | Laterally or rotating in space. |
| What are the three factors that dictate the fluidity of the membrane? | The length of the hydrocarbon tails, the presence of unsaturated fatty acids, and the presence of steroids. |
| Is the fluidity of the membrane is inreased by shorter or longer hydrocarbon tails? | Shorter |
| Why does the presence of unsaturated fatty acids in phospholipids help the membrane molecules to move more freely? | Unsaturated fatty acids are liquid at room temperature, therefore making the much more fluid than saturated fatty acids. |
| How do steroids affect the fluidity of the membrane? | At a warmer temperature, steroids make the membrane more stable while lower temperatures cause more fluidity. |
| Why is the membrane made of two layers of phospholipid molecules instead of one? | The membrane always exists between environments that contain water, and phospolipid molecules are only hydrophobic on the tails. Doubling up makes it where the hydrophobic tails of both the outer and innder layers are protected from the water. |
| In the outer layer, which way do the hydrophilic heads point? | They point outward |
| In the inner layer, which way do the hydrophobic tails point? | They point inward |
| What does every integral membrane protein contain? | One hydrophibic region and one hydrophilic region. |
| What makes up a lipid anchored protein? | A lipid component, embedded in the membrane, is attached to a protein that is exposed to either the cytosol or the extracellular environment. |
| What do transmembrane proteins contain? | Two hydrophilic regions and one hydrophobic domain. |
| What is the purpose of the hydrophobic domain in a transmembrane protein? | It is used to form helical structures. |
| Do peripheral membrane proteins contain a hydrophobic region? Why or why not? | No because they are not part of the membrane. |
| What kind of regions can a peripheral membrane protein contain? How do these regions affect the protein? | Polar or charged regions which allow them to interact with the hydrophilic region of the integral membrane proteins or the polar portion of the phospholipid molecules. |
| Name 4 roles that peripheral membrane proteins play within a cell. | Signal relay from receptor to the nucleus; electron or small molecule transport; maintain cytoskeleton for cell shape and support; are near membrane enzymes to catalyze reactions. |
| Chemical reactions that occur on or near the membrane need what nearby to facilitate these reactions? | Enzymes |
| Name two forms an enzyme can exist as. | Monotopic or peripheral. |
| How do cell surface receptors function? | They capture ligands and relay information to the inside of the cell, which is how cells often communicate to each other or respond to changes in the environment. |
| Name 2 characteristics of identity markers. | They are made up of glycoproteins and signal cell type to the immune system. |
| What region is the exposed part of a glycoprotein? | Carbohydrate region |
| How do cells interact with extracellular activities? | Membrane proteins connect the plasma membrane and the internal "scaffold" system of the cytoskeleton. |
| Peripheral membrane proteins are _____ the membrane | Near |
| Transmembrane proteins are _____ the membrane | All the way through |
| Lipid anchored proteins are ______ the membrane | Partly in |
| Integral membrane proteins are ______ in the membrane | Embedded |
| How do molecules travel naturally? | Molecules are shaking constantly which causes them to collide with other molecules and move away from where they contact each other. |
| Diffusion is a natural process that occurs in what types of environments? | Solid, liquid, and gas. |
| Does diffusion require any additional input of energy? Why or why not? | No because the driving force of diffusion is the concentration gradient. |
| Concentration gradient is a form of what energy? | Potential energy |
| Describe diffusion in a liquid environment. | Solute diffuses away from the highest concentration area to where the concentration is the lowest until it is evenly distributed within the beaker, also known as reaching equilibrium. |
| What environment does diffusion occur the slowest in? | Solid environment |
| Name 3 factors that affect the diffusion rate. | Size of the molecules, temperature of the environment, and the concentration gradient of the molecule. |
| Explain how the size of molecules affects diffusion rate. | Smaller molecules diffuse faster, their size allowing them to zip around other larger molecules with ease. |
| Explain how the temperatre of an environment affects diffusion rate. | The faster molecules shake, the higher the amount of kinetic energy, the warmer the environment becomes. Basically, higher temperature = increased diffusion rate; lower temperature = decreased diffusion rate. |
| Describe the relationship between the concentration gradient and the diffusion rate. | The greater the concentratin difference, the faster the molecules diffuse. |
| Does diffusion require the presence of a membrane? | No |
| Biological membranes are ______. | Selectively permeable |
| Name 2 major types of diffusion that carries out passive transport. | Simple diffusion and facilitated diffusion. |
| What are the characteristic of molecules that are able to move across the membrane through simple diffusion? | They are usually very small, nonpolar, hydrophobic, and gas molecules. |
| What two types of facilitated diffusion that occur across the plasma membrane? | Facilitated diffusion by channel proteins and facilitated diffusion by transporters. |
| Describe facilitated diffusion by channel proteins. | Channel proteins allow small, charged solutes to go through and down the concentration gradient, which results in a quick change of concentration. |
| Give 2 examples of channel proteins. | Ion channels and aquaporin |
| Describe facilitated diffusion by transporters. | A solute binds in a hydrohilic pocket exposed on one side of the membrane. Then the transported undergoes a conformational change that switches the exposure of the pocket to the other side of the membrane, where the solute is then released. |
| Give 2 examples of transporters. | GLUT1 glucose carrier and amino acid transporter. |
| Why are some substances more permeable than others? | The innter portion of the membrane is hydrophobic, which causes polar molecules more likely to be rejected as it tries to pass through. Large molecules are also usually too large to go through the small space between lipid heads. |
| Put the following molecules in order from highest permeability to lowest: A. Gases B. Sugars C. Ions D. Amino Acids E. Water | A, E, B, C, D |
| Name the two different types of concentration gradients. | Chemical gradient and electrochemical gradient. |
| How are signals transmitted in our nervous system? | Neurons maintain an electrochemical gradient across the plasma membrane in order to conduct electrical signal. |
| What happens to the nervous system if the electrochemical gradient is gone? | It will enter a state of paralysis. |
| Which two organelles utilize the electrochemical gradient? What do they produce? | Mitochondrion and chloroplast use the electrochemical gradient to produce ATP. |
| Osmosis is affected by the ____ solute concentration, not by ____ solute concentration. | total; individual |
| If a cell has a 1% solute concentration on the inside and a 1% solute on the outside, what condition is this? | Isotonic |
| How will water move in an isotonic condition? Will the cell size change? | The amount of water that moves to inside the cell will be the same amount that moves to outside the cell. Therefore there will be no cell size change. |
| Describe how a red blood cell looks in an isotonic condition. | The middle of the cell caves in slightly, appearing darker in the center. |
| Describe a plant cell in an isotonic condition. | The central vacuole will have a normal volume, which means the nucleus won't be pushed up againt the cell wall. The nucleus will remain roundish. |
| If a cell has a 1% solute concentration on the inside and a 0.8% concentration on the outside, which region is hypotonic? Which region is hypertonic? | The outside of the cell is the hypotonic region and the inside of the cell is the hypertonic region. |
| How will water move in a hypotonic region? What is the result? | Water molecules will move into the hypotonic region, resulting in swelling of this region. |
| How will water move in a hypertonic region? What is the result? | Water molecules will move out of the hypertonic region, resulting in this region shriveling up. |
| How will swelling affect animal cells? | The animal cell could end up lysing (bursting). |
| How will swelling affect plant cells? | The plant cell's nucleus will look more like a kidney bean due to the central vacuole having a higher volume. |
| Why don't plant cells risk lysing unlike animal cells? | Plant cells have cell walls that are able to resist lysing because the wall prevents the cell from taking in too much water. Animal cells don't have cell walls. |
| Plasmolysis and crenation are process that occur in what condition? | Hypertonic |
| Does osmosis require the presence of a semi-permeable membrane? | Yes |
| Water moves from a ____ solute environment to a ____ solute environment. | low; high |
| Transporters are involved in ____ transport as well as ____ transport. | Passive and active |
| All transporters are made of what kind of proteins? | Transmembrane proteins |
| What are the three types of transporters? | Uniporter, symporter, and antiporter. |
| Give an example of each type of transporter. | Uniporter: GLUT1 transporter Symporter: Sodium-glucose symporter Antiporter: Sodium-potassium pump |
| How do cells accomplish active transport? | By supplying cellular energy to activate channels or pumps, or by wrapping molecules in a vesicle, to move molecules from a lower concentration area to a higher concentration area. |
| What allows plant cells to photosynthesize and nerve cells to transmit nerve impules? | The ability to keep a concentration imbalance. |
| What is the energy from an ATP molecule used for? | To transport molecules. |
| In a sodium-potassium pump, where are sodium ions and potassium ions placed? | Sodium ions are placed outside of the cell while potassium ions are placed inside the cell. |
| How is a sodium potassium pump activated? | By the hydrolysis of an ATP molecule. |
| What is the ratio of sodium ions to potassium ions? | 3:2 |
| List all 3 ways of moving molecules or ions across the selective permeably membrane. | Diffusion, facilitated diffusion, and active transport. |
| "EN"docytosis = ? | ENter cell |
| "EX"ocytosis = ? | EXit cell |
| Name 3 reason why cells secrete molecules. | To communicate with other cells; to digest contents outside the cell; to facilitate building other structures. |
| In endocytosis, the plasma membrane ____ or ____ substances it wants to bring in | Grabs; identifies |
| Name the 3 types of endocytosis. | Phagocytosis, pinocytosis, and receptor-mediated endocytosis. |
| Phago = ? | To eat |
| Pino = ? | To drink |
| Give an example of phagocytosis. | White blood cells will eat bacteria when they encounter them. |
| Describe how receptor mediated endocytosis works. | Clustered receptor proteins in coated pits capture and bind ligands, causing the membrane to invaginate and the coated vesicle will bring the molecules in. |
| Why are transmembrane proteins able to span the hydrophobic portion of the bilayer? | Becuase these proteins have stretches of nonpolar amino acids. |
| Where would peripheral membrane proteins likely reside with respect to the plasma membrane? | On the outside of the outer leaflet, facing the outside of the cell and on the outside of the inner leaflet, facing the cytoplasm. |
| How is a lipid anchored protein attached to the membrane? | Covalently bound to an amino acid side chain within the protein. |
| The cytosolic leaflet of the plasma membrane faces ________. | The inside of the cell |
| What regions are likely binding sites for peripheral membrane proteins? | Polar heads of phospholipids and hydrophilic regions of integral membrane proteins. |
| Membrane proteins that span both leaflets of the lipid bilary have transmembrane segments that are composed of what kind of amino acids? | Nonpolar |
| What type of interactions are typically involved in peripheral proteins binding to biological membranes? | Ionic and hydrogen bonds |
| Movement of ions and large molecules into and out of the cell is mediated by what? | Membrane proteins |
| What is a membrane protein that has a portion integrated into the hydrophobic region of the membrane called? | Integral membrane protein |
| How do most phospholipid move freely within a semifluid membrane? | Laterally along the plane of the membrane in two dimensions. |
Created by:
Inkie27
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