Ch. 3 & Lab Exercise 2 Cells And Cell Transport (Study Guide) Flashcards
List the parts of a “representative cell”
- Nucleus (Nuclear envelope, Nucleolus, Chromatin)
- Cytoskeleton (Microtubule, Microfilament, Intermediate filament)
- Rough ER
- Smooth ER
- Golgi apparatus
- Lysosome
- Mitochondrion
- Peroxisome
- Plasma membrane
- Centrosome with pair of centrioles
- Cytoplasm (Cytosol, Organelles)
Describe the structure (anatomy) of the plasma membrane.
-surrounds the entire cell
-regulates the entry and exit of substances
-selectively permeable (only certain substances are allowed to pass through
- flexible, not fixed or rigid
Name the 4 major categories of proteins found in the plasma membrane.
Describe the specific functions associated with membrane proteins.
Functions of membrane proteins:
- Structural- Anchor to intracellular/extracellular components
- Channels- site of transport of larger molecules across membrane
- receptors- site of chemical activity which allows for cell interaction
- Cellular ID- recognition of cell type and/or who it belongs to
-Carriers
- Enzymes
-Anchors
-identifiers
What are the functions associated with carbohydrates and cholesterol within the plasma membrane?
Cholesterol:
- Decreases permeability to small molecules
- Provides some structural stability
- Amount varies from cell type to cell type
Carbohydrate:
- Join with proteins and lipids to form complex molecules on the outer surface of the membrane.
-Functions as cell lubricants and adhesives and act as receptors for compounds outside the cell.
Describe the overall functions associated with the plasma membrane and which components of the membrane are responsible for those functions.
- Physical isolation: the plasma membrane is a physical barrier that separates the inside of the cell from the very different surrounding extracellular fluid to maintain homeostasis.
- Regulation of exchange with the environment: the PM controls the entry of ions and nutrients, the elimination of wastes, and the release of secretions.
- Sensitivity to the environment: The PM is the first part of the cell affected by changes in the extracellular fluid. Contains molecules that act as receptors, enabling the cell the recognize and respond to specific molecules in its environment.
- Structural support: Specialized connections between plasma membranes, or between membranes and materials outside the cell, give tissues a stable structure.
Define intracellular fluid vs. extracellular fluid.
Name the specific examples of each.
Intracellular fluid: Cytosol (the fluid portion of the cytoplasm inside the plasma membrane)- contains dissolved nutrients, ions, soluble and insoluble proteins, and waste products
Extracellular fluid: Interstitial fluid, (watery, surrounding environment outside of the plasma membrane)
Define “passive” processes of movement.
- Movement of a substance along its concentration gradient.
- From an area of high concentration to an area of low concentration
- Does not require cellular E
- Types: diffusion, osmosis, facilitated diffusion, filtration
What are the 4 common passive processes of movement that commonly occur in the body?
Describe each and provide specific examples of each.
- Diffusion - Movement a of substance from an area where its concentration is relatively high to an area where its concentration is lower. Diffusion occurs until the concentration gradient is eliminated.
EX: Respiration - Oxygen, whose concentration is higher in lungs than that in the blood get diffused into blood and carbon dioxide, whose concentration is higher in blood gets diffused back to lungs.
- Facilitated diffusion - A passive transport process for compounds that are insoluble in lipids and too large to fit through membrane channels.
EX: Glucose transport - The glucose transporter works with the concentration gradient to move the glucose across the cell membrane.
- Osmosis - The diffusion of water across a selectively permeable membrane in response to differences in concentration.
EX: Water moves in and out of the kidney structures called nephrons, in order to help balance out your salt and pH levels.
- Filtration - Movement of fluid across a membrane whose pores restrict the passage of solutes on the basis of size.
EX: The urinary system - works as a filtration system by removing toxins and wastes from your body as urine.
What factors can influence diffusion across the plasma membrane?
- If the compounds are insoluble in lipids or not
- Their size (whether they can fit through membrane channels)
- Concentration levels on either side of membrane (concentration gradient)
Define osmotic pressure and describe how it influences water movement in the body.
Osmotic pressure of a solution is an indication of the force of water movement into that solution as a result of solute concentration.
As the solute concentration of a solution increases, so does its osmotic pressure.
Describe isotonic, hypertonic, and hypotonic solutions. Explain the effects that each of these solutions have will have on body cells.
- Isotonic: does not cause a net movement of water into or out of the cell, red blood cells retain their normal dimpled appearance. Equilibrium exists, as one water molecule moves out of the cell, another one replaces it.
- hypertonic: Red blood cells in a hypertonic solution will lose water by osmosis. As they do, they shrivel and dehydrate.
Define “active” processes of movement.
- Movement of a substance against its concentration gradient
- From an area of low concentration to an area of high concentration.
- Requires cellular E
- Types: protein pumps, endocytosis, exocytosis.
Describe/define the common active processes that occur in the body
- active transport
- receptor mediated endocytosis
- pinocytosis
- phagocytosis
- exocytosis
Give examples of how and where these occur in the body.
- Active transport: Movement against a concentration gradient involving a carrier protein ( ion pump)
EX: Movement of ions such as Na+ and K+ across a plasma membrane
- Receptor mediated endocytosis: Produces vesicles containing a specific target molecule in high concentrations.
EX: Molecules in the extracellular fluid bind to receptors on the plasma membrane surface. The receptors bind to target molecules called ligands (such as transport proteins), then cluster together on the plasma membrane. This area of the membrane with bound receptors pinches off to form a vesicle. (Cholesterol and iron ions are carried throughout the body on transport proteins too large to pass through the membrane channels, but can enter through receptor mediated endocytosis.
- Pinocytosis: (cellular intake of fluid) The introduction of fluids into the cytoplasm by enclosing them in membranous vesicles at the cell surface. “cell drinking”. Produces vesicles containing solid objects that may be as large as the cell itself.
EX: Skin cells
- Phagocytosis: Cellular intake of solid material. The engulfing of extracellular materials of pathogens; movement of extracellular materials into the cytoplasm by enclosure in a membraneous vesicle.
EX: Macrophages
- Exocytosis: The ejection of cytoplasmic materials by fusion of a membranous vesicle with the cell membrane. A vesicle created inside the cell fuses with the plasma membrane and discharges its contents into the extracellular environment.
EX: The ejection of waste products from the recycling of damaged organelles.
Describe the structure (consistency) of cytosol and functions associated with cytosol.
Fluid portion within the cell. Components (water, ions, proteins, amino acids, lipids) concentration gradients are within the cell, making the cytosol complex.
The cytosol helps break down waste products and moves materials around the cell.
- Higher concentration of potassium ions in cytosol.
- Lower concentration of sodium ions in cytosol.
- Higher concentration of suspended proteins.
Describe the anatomy of the nucleus. Do all body cells have a nucleus? What is the function of a nucleus? Why is it important?
- Command center of the cell containing genetic info (DNA), nuclear envelope, pores on membrane which regulates the passage of small substances, and nucleolus which is the site of RNA synthesis.
- Prokaryotic cells (bacteria) do not contain a nucleus.
- Eukaryotic cells (plants, animals, fungus) have a nucleus.
- Genetic material (DNA) in the Nucleus will determine what kind of cell it will be.
