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Histology MT4
Histology MT4 A&P Chap. 3
| Question | Answer |
|---|---|
| Cell Biology | The study of cellular structure and function |
| Three main parts of the cell | plasma membrane, cytoplasm, and nucleus |
| Plasma Membrane | forms the cell's flexible outer surface, acts as a barrier, referred to as the "Fluid Mosaic Model" |
| Cytoplasm | consists of all the cellular contents between the plasma membrane and the nucleus |
| Cytosol | the fluid portion of cytoplasm, contains water, dissolved solutes and suspended particles. |
| Nucleus | a large organelle that houses most of a cell's DNA |
| Chromosome | single molecule of DNA associated with several proteins, contains thousands of hereditary units called genes that control most aspects of celluar structure and function. |
| Plasma Membrane is composed of | proteins and lipids |
| What does the lipid bilayer consist of | two back to back layers of phospholipids, cholesterol, and glycolipids. |
| Why does the bilayer arrangement of Plasma Membranes occur | The lipids are amphipathetic, having both polar and nonpolar parts. |
| What are the integral proteins | Glycoproteins, with sugar groups attached to the ends that face the extracellular fluid. Together with glycolipids, the glycoproteins form a glycocalyx on the extracellular surface of cells |
| Integral Proteins | channels and carriers that help specific solutes cross the membrane |
| Receptors | serve as cellular recognition sites |
| enzymes | catalyze specific chemical reactions (like digestion) |
| Linkers | anchor proteins in the plasma membranes to protein filaments inside and outside the cell. |
| Peripheral Proteins | serve as enzymes and linkers; support the plasma membrane; anchor integral proteins and participate in mechanical activities |
| Membrane glycoproteins | function as cell identity markers |
| membrane fluidity | greater when there are more double bonds in the fatty acid tails of the lipids that make up the bilayer. |
| What does cholesterol do to the lipid bilayer | Makes the lipid bilayer stronger but less fluid at normal body temp. Fluidity allows interactions to occurs within the plasma membrane, enables the movement of membrane components, and permits the liped bilayer to self seal when torn or punctured. |
| What does the membrane`s selective permeability permit? | permits some substances to pass more readily than others. lipid bilayer is permeable to most nonpolar, uncharged molecules |
| What is the membrane impermeable to? | Ions and charged or polar molecules other than water and urea. |
| What do channels and carriers do? | increase the plasma membrane's permeability to small and medium sized polar and charged substances, including ions, that cannot cross the lipid bilayer. |
| What does the selective permeability of the plasma membrane support? | The existence of concentrations of chemicals between one side of the membrane and the other. |
| Passive processes of transport across the plasma membrane: | a substance moves down its conentration gradient across the membrane using its own kinetic energy of motion. |
| Active processes: | cellular energy is used to drive the substance uphill against its concentration gradient. |
| Diffusion | molecules or ions move from an area of higher concentration to an area of lower concentration until an equilibrium is reached. |
| What is the rate of diffusion across a plasma membrane affected by? | the steepness of the concentration gradient, temperature, mass of the diffusion substance, surface area available for diffusion and the distance over which diffusion must occur. |
| What diffuses through the lipid bilayer of the plasma membrane via simple diffusion | Nonpolar, hydrophobic molecules such as oxygen, carbon dioxide, nitrogen, steroids and fat soluble vitamins (A, E,D and K) plus small, polar uncharged molecules such as water and urea and small alcohols. |
| What occurs in channel-mediated facilitated diffusion? | a solute moves down its concentration gradient across the lipid bilayer through a membrane channel |
| Carrier mediated diffusion | a solute such as glucose binds to a specific carrier protein on one side of the membrane and is released on the other side after the carrier undergoes a change in shape. |
| Osmosis | Type of diffusion in which there is net movement of water through a selectively permeable membrane from am area of higher water concentration to an area of lower water concentration. |
| What occurs in an isotonic solution | RBC's maintain their normal shape; in a hypotonic solution, they undergo hemolysis; in a hypertonic solution they undergo crenation |
| How can substances cross the membrane against their concentration gradient? | By active transport. |
| What do actively transported substances include? | Ions such as Na+, K+, H+, Ca2+, I-, and Ca-; amino acids; and monosaccharides. |
| What two sources of energy are used to drive active transport? | Energy obtained from hydrolisis of ATP is the source in primary active transport, |
| What occurs in endocytosis? | Tiny vesicles detach from the plasma membrane to move materials across the membrane into a cell. |
| What occurs in exocytosis? | vesicles merge with the plasma membrane to move materials out of a cell. |
| What is receptor mediated endocytosis? | the selective uptake of large molecules and particles (ligands) that bind to specific receptors in membrane areas called clathrin-coated pits. |
| Phagosytosis | The ingestion of solid particles. Some WBC's destroy microbes that enter the body in this way. |
| Bulk Phase endocytosis (Pinocytosis) | the ingestion of extracellular fluid, a vesicle surrounds the fluid to take it into the cell. |
| Transcytosis | vessicles undergo endocytosis on one side of a cell, move across the cell and undergo exocytosis on the opposite side. |
| Cytoplasm | All the cellular contents within the plasma membrane except for the nucleus. Consists of cytosol and organelles |
| Cytosol | the fluid portion of cytoplasm, containing water, ions, glucose, amino acids, fatty acids, proteins, lipids, ATP, and waste products. The site of many chemical reactions required for a cell's existence. |
| Organelles | Specialized structures with characteristic shapes that have specific functions |
| Components of the cytoskeleton | a network of several kinds of protein filaments that extend throughout the cytoplasm, include microfilaments, intermediate filaments, and microtubules. |
| What does the cytoskeleton provide? | A structural framework for the cell and is responsible for cell movements. |
| What does the centrosome consist of? | Pericentrioler material and a pair of centrioles. Organizes microtubles in nondividing cells and the mitotic spindle in dividing cells. |
| Cilia and flagella: | motile projections of the cell surface, are formed by basal bodies. |
| Cilia | move fluid along the cell surface |
| Flagella | move an entire cell (ie sperm cell) |
| What do ribosomes consist of? | two subunits made in the nucleus that are composed of ribosomal RNA and ribosomal proteins. Serve as sites of protein synthesis. |
| Endoplasmic Reticulum (ER) | network of membranes that form flattened sacs or tubules; extends from the nuclear envelope throughout the cytoplasm |
| Rough ER | Studded with ribosomes that synthesize proteins, proteins then enter the space within the ER for processing and sorting. |
| What does rough ER produce? | secretory proteins, membrane proteins and organelle proteins; forms glycoproteins; synthesizes phospholipids; and attaches proteins to phospholipids. |
| Smooth ER | lacks ribosomes. Synthesizes fatty acids and steroids; inactivates or detoxifies drugs and other potentially harmful substances. |
| Smooth ER also: | removes phosphate from glucose-6-phosphate; and stores and releases calcium ions that trigger contraction in muscle cells. |
| Golgi complex | consists of flattened sacs called cisternae. |
| The Cell | Basic Functional unit of all living things, must start with at least one cell to be considered living. |
| How many cells inside the human body? | 50-60 trillion cells |
| What are you lacking when you are dehydrated? | cytosol cells |
| Cytoplasm | Any inside contents |
| Cytosol | liquid portion in cytoplasm |
| Cell is: | a little functional factory. Every cell has main components that they all contain. |
| Where is the nucleus typically located? | Slightly off centre but in the middle. Everything needs to be able to access it. |
| Phospholipid bilayer | forms the fabric of the membrane; is relatively impermeable to most H2O soluble molecules. Consists of 2 parrallel sheets of phospholipid structure. |
| Proteins | Located throughout; 2 types, integral, peripheral. |
| Integral Membrane Proteins | travel through the entire plasma membrane; act as receptors (chemical levels etc.); acts as carriers / channel |
| Peripheral Membrane Proteins | are only exposed on one side of the membrane; contain enzymes; perform mechanical functions( ie. can change shape and therefore change the shape of the cell.) |
| Enzymes | Act as a catalyst to assist in breaking things down. |
| Glycocalyx | Carbohydrates attaced to proteins on the cell exterior; contains membrane receptors; performs "contact signalling" and "chemical signalling" |
| Contact Signalling | as cells move around they need to know what is around them in their environ. Essentially tells a cell "what they are up against" |
| Contact Signalling | Physically around it. Mechanical. Physical |
| Chemical Signalling | Act as receptors, have special endings on them so that only specific molecules can bind to them. |
| Chemical Signalling | Chemically around it. Liquid. Chemical |
| Cholesterol | A form of lipid (fat) which provides stability |
| microvilli | finger like projections of the plasma membrane |
| What do microvilli do? | Increase the surface area; important for chemical Rxn's; found primarily in cells with absorptive properties |
| Greater surface area ='s | Greater rate of absorption |
| Mitochondria | Powerhouse of the cell, self replicative, contain their own DNA |
| How many mitochondria are contained in a cell? | 100's - 1000's. No specified amount, amount varies constantly |
| What does Mitochondria do? | Produces and uses large amounts of ATP (Adenosine Triphosphate) |
| What is Mitochondria part of? | Cellular respiration (=how ATP is produced) |
| What is the matrix of the mitochondria? | Centre of the membrane. |
| Cristae are: | Folds in the matrix that produce increase surface area for chemical Rxn's to produce ATP. |
| What is located on the cristae? | enzymes for catalyzing |
| Peroxisomes (name is specific to function) | fxn to protect the cell for the toxic effects of H2O2. Which is the biproduct of oxidation. New peroxisomes form from pre-existing ones. |
| Peroxisomes are: | a detoxifying organelle. (neutralizes toxins and waste products) |
| Peroxisomes are similar to: | Lysosomes, only smaller. |
| Endoplasmic Reticulum (ER) | extension of the nucleus; network of flattened sacs. Stores and releases calcium ions in the mm's. |
| Rough ER | covered in Ribosomes (protein synthesis) and attached to the nuclear envelope; makes glycoproteins and phospholipids that are transferred to the plasma membrane |
| Smooth ER | Lack ribosomes; makes fatty acids and steroids and inactivates drugs and alcohol. |
| What are ER's called when they are located in the mm's? | Sarcoplasmic Reticulum. |
| Golgi Apparatus/ Complex | traffic director of the cell. Sorts pkgs and modifies and transports proteins that it receives from the rough ER |
| Lysosomes | membranous sacs that contain digestive enzymes, sites of intracellular digestion, allow digestion/ destruction of toxins/ pathogens to occur safely w/n a cell. |
| Microtubules | the railway track w/n the cell that transports things from one area to another. Thickest of cell fibres. |
| What do microtubules contain: | centrosome- area that co-ordinates building/ breaking of microtubules. |
| Centrioles are essential for: | tubular extension |
| A pair of Centrioles is: | Centrosome |
| Microfilaments: | thinnest element of the cytoskeleton, most commonly found at the sides of the cilli |
| Function of Microfilaments: | to generate movement, are involved in mm contraction, cell division, cellular locomotion. |
| Microfilaments provide: | mechanical support. Provide the main support that is responsible for the basic strength and shape of cells. |
| Cilia | hair like projections which aid in the movement of fluid |
| What do Cilia do? | Line internal structures of the body that have natural openings to the external portion of the body (ie. respiratory tract) |
| How do Cilia move? | stiff on movement stroke and flaccid on back stroke. Propels things past of overtop of the cell. Shaped like an oar. |
| Flagella | Long, hair like projections (similar to cilia but longer), located on the cell membrane, move the entire cell (ie sperm cell) |
| Ribosome | composed of proteins, site of protein synthesis. |
| Free Ribosomes make: | soluble proteins that synthesize proteins destined for inc. into the cellular membrane. |
| Nucleus | usually located in the centre of the cell, largest part of the cell(organelle)Contains DNA |
| 3 Regions of the nucleus: | 1)nuclear envelope (outer surface) 2) Nucleoli - centre of nucleosis 3) Chromatin - DNA and cellular replication |
Created by:
annette.rmt
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