Term
| Describe the Cell Theory. |
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Definition
| The Cell Theory (proposed by Theodor Schwann in 1839) states that: 1. All organisms consist of one or more cells. 2. The cell is the basic unit of structure for all organisms. 3. All cells arise only from preexisting cells. |
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Term
| Is the cell in a "static-state?" |
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Definition
| No; the cell is in a "dynamic" state. |
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Term
What is the relationship between cell structure and function?
a. Give an example. |
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Definition
| Structure dictates function. |
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Term
What are the three primary regions of a cell?
a. What is the primary function of each region? |
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Definition
Plasma membrane (outer barrier of the cell) regulates passage of molecules in/out of the cell.
Cytoplasm (everything inside of the cell) is a complete mixture of organelles, cytosol, and inclusions.
Nucleus controls cellular activities and contains genetic material. |
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Term
| Describe the fluid mosaic model. |
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Definition
| Proposed by S.J.Singer and G.L. Nicholson, the FMM states that the plasma membrane is a fluid mosaic of lipids and proteins. It is an asymmetric lipid bilayer with proteins dispersed throughout. |
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Term
| Describe the difference between an integral protein and a peripheral protein. |
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Definition
An integral protein is amphipathic (hydrophobic AND hydrophilic properties). They are embedded "in" the plasma membrane.
Peripheral proteins are polar (hydrophilic). They are attached on the outside of the plasma membrane. |
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Term
| What is the function of cholesterol in the plasma membrane? |
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Definition
| Cholesterol is an amphipathic molecule that regularly disrupts the membrane, and helps to keep the membrane fluid (freely moving). |
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Term
| List the six different functions of proteins in a plasma membrane. |
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Definition
1. Transport - channel (open all of the time) - carrier (opens only when bound to certain molecules)
2. Cell-cell recognition - Glycoprotein "fingerprints" the cell (secret handshake)
3. Receptors - specific shape to bond with certain molecules
4. Enzymatic activity - control specific chemical reactions
5. Cell adhesion (cell adhesion molecules) CAMs temporarily bind adjacent cells
6. Attachment- Cytoskeleton; extracellular matrix (ECM); a lot of attachment "arms" |
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Term
| What are the three recognizable structures of the nucleus? |
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Definition
1. Nuclear envelope - double plasma membrane around the nucleus; two phospholipid bilayers; has pores
2. Nucleoli - premanufacture and assemble ribosomes; lacks a membrane
3. Chromatin - genetic material; DNA loosely packaged with proteins (histones) |
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Term
| Can a cell have more than one nucleus? |
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Definition
| Yes; a cell can be mononucleate (one), multinucleate (more than one), or anucleate (no nucleus). |
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Term
| What structure of the cell is the site of ribosome subunit assembly? |
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Definition
| The nucleoli is the site of ribosome subunit assembly. |
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Term
| What are the major components of the cytoplasm? |
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Definition
1. Cytosol (sol=solution) - fluid suspends organelles
2. Organelles - specialized design and function
3. Inclusions - chemical substances (cell type...e.g. stored nutrients, lipid droplets, pigment) |
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Term
| (Part 1) List the cellular organelles (separate, membrane-bound compartments). a. What is the major function of each? |
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Definition
(Part 1)
1. Rough endoplasmic reticulum - membrane with ribosomes a. Synthesizes proteins for 1. secretion and2. membrane construction. 3. Abundant in cells that produce specific proteins to be secreted outside of the cell (e.g. plasma cells and pancreatic cells)
2. Smooth endoplasmic reticulum - network of fluid-filled tubules and flattened sacs (WITHOUT ribosomes) a. Stores calcium. Is modified in some cells. Abundant in cells that specialize in lipid metabolism (steroid synthesis/inactivation)
3. Golgi Bodies (Complex)- not physically connected to ER, stacked and flattened membranous sacs that receive proteins in transport vesicles from rough ER; modifies, packages, and distributes products for secretion by exocytosis; forms lysosomes. |
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Term
| (Part 2) List the cellular organelles (separate, membrane-bound compartments). a. What is the major function of each? |
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Definition
(Part 2)
4. Lysosomes (has proteins in them) - membranous sacs with protiens, enzymes that catalyze the separation of chemical bonds with the addition of water; destroy foreign substances and cellular debris; degrade non-functional/old organelles; is the intracellular "digestive system."
5. Peroxisomes - membranous sacs that house 1. oxidases (use O2 to remove H, to form H2O2) and catalase (degrades H2O2 to produce H2O and O2; involved in B-oxidation (lipids/fats); detoxify various waste products
6. Mitochondria - major site of ATP production; contain enzymes for the citric acid cycle and the electron transport chain (respiratory chain); double membrane (bilayer); outside is smooth, cristae folds inside; density indicates cell E requirements; contains own DNA/RNA...different from that of the nucleus (mitochondrial DNA comes from mother) |
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Term
| What is the physical difference between the Rough ER and Smooth ER? |
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Definition
| The Rough ER has ribosomes embedded in its membrane, whereas the Smooth ER does not. |
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Term
| Where does protein synthesis occur? |
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Definition
| Protein synthesis occurs in/on ribosomes. |
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Term
| If a ribosome is "free," or unbound, where are its synthesized proteins used? |
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Definition
| Proteins synthesized by "free," or unbound, ribosomes are used in the cytosol (inside the cell). |
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Term
| If a ribosome is "attached," or bound, where are its synthesized proteins used? |
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Definition
| Proteins synthesized by "attached," or bound, ribosomes are used in the cell plasma membrane or outside of the cell. |
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Term
| What is the cytoskeleton? |
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Definition
| The cytoskeleton is a protein network that gives structure and support to the cell; allows for connections and transport; functions as an integrated whole; links other parts of the cell together; intracellular transport of the materials; suspension of organelles; mechanical support and structure; contraction; movement |
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Term
| What are the three types of cytoskeleton elements? |
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Definition
1. Mictrotubules (largest; made of tubulin)
2. Microfilaments (smallest; made of actin)
3. Intermediate filaments (intermediate; made of keratin) |
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Term
| What is the primary function of each cytoskeleton element? |
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Definition
1. Microtubules - Move cilia and flagella; distribute chromosomes during cell division; transport secretory vesicles between cell regions.
2. Microfilaments - function in contractile systems (muscles) and as mechanical stiffeners (GI microvilli)
3. Intermediate Filaments - Function in cell regions that are subjected to mechanical stress |
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Term
| Name and describe the major types of cell membrane junctions. |
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Definition
1. Tight junctions prevent the movement of dissolved materials between cells; there is no intracellular space where a tight junction exists.
2. Desmosomes bind cells together to distribute tension to minimize the chance of tearing when the cell is subjected to pulling forces. Found in tissues subject to mechanical stress (skin/heart).
3. Gap junctions are found in electrically excitable tissues (heart/smooth muscle) so that ion passage from cell to cell will sync electrical activity and contraction. |
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