Unit 2: Ch 3 (Cellular Form & Function) Flashcards
Vesicular Transport*
- Description
- Vesicle processes
- Processes and moves large particles, droplets, or molecules at once through the membrane
- Active primary transport
-
Endocytosis
- Bring matter into a cell
- Phagocytosis: “Cell eating”; large solids
- Pinocytosis: “Cell drinking”; smaller volumes, usually liquid
- Receptor-mediated: Specific protein or ligand is required for transport
-
Exocytosis
- Release matter from a cell
- Motor proteins energized by ATP
-
Transcytosis
- Matter brought into, through & removed from cell
- Sum or process of both exocytosis and endocytosis
-
Endocytosis
Active transport
- Description
- Types
- The movement of molecules across the cell membrane against the concentration gradient with the assistance of ATP
-
Primary active
- Directly uses ATP by transferring a phosphate group to the transport protein
-
Uniport: Carries only 1 type of solute
- Sodium-Potassium pump
- Exocytosis
- Endocytosis
- Transcytosis
-
Secondary active
- Transport of solute particles up their concentration gradient, by a carrier that doesn’t use ATP; indirectly uses ATP
- Cotransport/Symport: Carries 2+ solutes in same direction
- Countertransport/Antiport: Carries 2+ solutes in different directions
-
Primary active
- Reference
Aquaporins*
- Proteins that move water from one side of a cell membrane to another
- Cells can increase the rate of osmosis by installing more aquaporins in the membrane or decrease the rate by removing them
ATPase Pump*
- Moves sodium (Na) and potassium (K) ions across the cell membrance in an active transport process involving the hydrolysis of ATP to provide the necessary energy
- Responsible for maintaining the large excess of Na+ outside the cell and the large excess of K+ ions on the inside
- It accomplishes the transport of 3 Na+ to the outside of the cell and the transport of 2 K+ ions to the inside; left with a net charge of -1
- This unbalanced charge transfer contributes to the separation of charge across the membrane
- The sodium-potassium pump is an important contributor to action potential produced by nerve cells
- Notes
- Sodium
- An extracellular ion
- Found in high concentrations extracellularly
- Moves down the gradient
- Extracellular ion that moves 3+ charges to ICF
- Potassium
- Found in high concentrations intracellularly
- Intracellular ion that moves 2 ions to ECF
- Sodium
Carrier-Mediated Transport*
- A solute binds to a carrier in the plasma membrane, which then changes shape and releases the solute to the other side
- Transport protein required for movement (pH and temperature sensitive)
- Don’t chemically change their ligands
- Specificity: Only carries specific ligands
- Saturation: Transport maximum (Tm)
Cell Components*
- Plasma membrane (aka cell membrane & plasmalemma)
- Cytoplasm
- Nucleus
Cell Structure Identification*


Cell surface extensions
- Aid in the absorption, movement, and sensory processes
- Include:
- Microvilli
- Cilia
- Flagella
- Pseudopods
Cellular Membrane Transport
- Controls the passage of materials into and out of the organelles and cells
- Selectively permeable
Centrioles*
- Organelle that helps move genetic material
- Forms mitotic spindle during cell division
- 9 + 3 pattern (9 groups of 3)
Centrosome
- Function
- Appearance
- Organizing center for the formation of microtubules of cytoskeleton and mitotic spindle
- Clear area near nucleus containing a pair of centrioles
Channel Proteins
- Allow water and hydrophilic solutes to move through the membrane
- Leak channels: Always open and allow materials to pass through continually
- Gate channels: Open and close under different circumstances and allow solutes through at some times, but not others
Cilia*
- Move substances across the superior border of a cell
- Nonmotile & motile
- 9 + 2 pattern (9 groups of 2)
- Widespread sensory roles (equilibrium, smell, vision)
Clathrin
- Serves as an “address label” on the coated vesicle that directs the vesicle to an appropriate destination in the cell
Cristae
- A crista is a fold in the inner membrane of a mitochondrion
- Increases surface area, which increases area for chemical reactions and diffusion to occur on
- Aids aerobic cellular respiration, because the mitochondrion requires oxygen
Cuboidal
- Squarish-looking in frontal sections and about equal in height and width
- Example: liver cells
Cytoskeleton Structure Identification (1 of 2)


Cytoskeleton Structure Identification (2 of 2)


Cytoskeleton*
- Function
- Components
- Determines the shape of the cell
- Made of proteins
- Function
- Lends structural support
- Directs movement of substances through the cell (transcytosis)
- Contributes to the movements of the cell as a whole
- Components
- Microfilaments (smallest size)
- Intermediate fibers (middle size)
- Microtubules (largest size)
Diffusion
- The net movement of particles from a place of high concentration to a place of lower concentration as a result of their constant, spontaneous motion
- Diffuse down their concentration gradients
Diffusion Rates*
- Description
- Influencing factors
- Determine how quickly a cell can acquire nutrients or rid itself of wastes
- Factors impacting the rate of diffusion:
- Temperature
- Molecular weight
- The steepness of the concentration gradient
- Membrane surface area
- Membrane permeability
Endocytosis*
- Description
- Forms
- Active primary transport
-
Phagocytosis
- Only occurs in a few specialized cells
- Process of engulfing particles such as bacteria, dust, and cellular debris large enough to be seen with a microscope
- “Cell eating”
-
Pinocytosis
- “Cell drinking”
- Process of taking in droplets of ECF containing molecules of some use to the cell
- Occurs in all human cells
-
Receptor-mediated endocytosis
- Enables a cell to take in specific molecules from the ECF with a minimum of unnecessary matter
- Particles in the ECF bind to specific receptors on the plasma membrane. The receptors cluster and the membrane sinks in, creating a pit coated with a membrane protein called clathrin
-
Phagocytosis
Endoplasmic Reticulum (ER)*
- Description
- Types
- System of interconnected channels; “little network within the cytoplasm”
- 2 types:
- Rough ER (rER)
- Synthesizes proteins
- Smooth ER (sER)
- Does not modify proteins because it does not have any ribosomes
- Synthesizes & modifies lipids and carbohydrates
- Rough ER (rER)
Role of Plasma Membrane Enzymes
- Breaks down a chemical messenger and terminates its effect
- Note
- Enzymes in the plasma membrane carry out the final stages of starch and protein digestion in the small intestine, help produce second messengers and break down hormones and other signaling molecules whose job is done, thus stopping them from excessively stimulating a cell
Exocytosis
- Process of eliminating material from a cell by means of a vesicle approaching the cell surface, fusing with the plasma membrane, and expelling its contents
- Used to release cell secretions, replace worn-out plasma membrane, and replace membrane that has been internalized by endocytosis
- Examples
- Golgi Complex/Apparatus
Extensions of the cell surface
- Cilia
- Flagella
- Microvilli
- Pseudopods
Extracellular face of the plasma membrane
The side that faces outward
Extracellular Fluid (ECF)
All body fluids not contained in the cells
Facilitated Diffusion
- Carrier-mediated transport process of transporting a chemical through a cellular membrane
- Enables substances to diffuse through the membrane that would do so poorly, or not at all, without a carrier
- Down its concentration gradient
- Does not consume ATP
Filtration
- A process in which hydrostatic pressure forces fluid through a selectively permeable membrane
- Notes
- Seen in the blood capillaries, where blood pressure forces fluid through gaps in the capillary wall
- This is how water, salts, nutrients, etc, are transferred from the bloodstream to the tissue fluid and how the kidneys filter wastes from the blood
Flagella*
- Moves entire cell from one location to another
- Tail of a sperm
- Movement is more snakelike
Gated channel types
- Ligand-gated channels: Respond to chemical messengers
- Voltage-gated channels: Respond to changes in electrical potential (voltage) across the plasma membrane
- Mechanically-gated channels: Respond to physical stress on a cell, such as stretch or pressure
Glycocalyx
- Description
- Function
- A layer of carbohydrate molecules covalently bonded to the phospholipids and proteins of a plasma membrane
- Forms a surface coat on all human cells
- “Fingerprint” of a cell
- Function
- Protection
- Immunity to infection
- Defense against cancer
- Transplant compatibility
- Cell adhesion
- Fertilization
- Embryonic development
Golgi Complex/Apparatus*
- Manufacturing and shipping center of the cell
- Helps edit, revise & create the final protein
- Cis (Closer to the ER): Receives protein & “proofreads” it
- Medial: Adds carbs or modifies to a macromolecule
- Trans (Further from the ER): Final “proofreading”
- Endpoint for protein and glycoprotein synthesis
- A form of exocytosis transport
Hydrostatic Pressure
- The physical force exerted against a surface by a liquid such as blood or tissue fluid, as opposed to osmotic atmospheric pressures
Hypertonic*
- Higher concentration of nonpermeating solutes than the ICF
- It causes cells to lose water and shrivel (crenate)
- Such cells may die of torn membranes and cytoplasmic loss
Hypotonic*
- Has a lower concentration of nonpermeating solutes than the ICF
- Cells absorb water, swell, and may burst
Inclusions
- Accumulated cell products such as glycogen granules, pigments, and oil droplets
- Foreign bodies such as viruses, bacteria, and dust particles, and other debris phagocytized by a cell
- Never enclosed in membranes
- Not essential to cell survival
Intermediate Filaments
- Appearance
- Function
- Appearance
- Thicker protein filaments (8-10 nm in diameter) extending throughout cytoplasm or concentrated at cell-to-cell junctions
- Function
- Give shape and physical support to cell
- Anchor cells to each other and to extracellular material
- Compartmentalize cell contents
Intracellular Face
The side that faces the cytoplasm of the membrane
Intracellular Fluid (ICF) / Cytosol
The cytoskeleton, organelles, and inclusion embedded in a clear gel
Isotonic*
- The total concentration of nonpermeating solutes is the same as in the ICF
- No change in cell volume or shape
Lysosomes*
- Description
- Function
- Weak acidic (4-6 pH) enzymes bound by a single destructive organelle
- Destroys macromolecules via intracellular hydrolytic digestions
- Autophagy: Programmed cell death
- Autolysis: Removed/rid cells via splitting or bursting; “cell suicide”
Membrane permeability types
- Freely permeable
- Impermeable
- Selectively permeable
Function of Membrane Proteins
- Receptors
- Second-messenger systems
- Enzymes
- Channel proteins
- Carriers
- Cell-identity markers
- Cell-adhesion molecules
Membrane Protein Physiology


Membrane transport methods
- Passive transport
- No energy or ATP required
- Diffusion
- Filtration
- Osmosis
- No energy or ATP required
- Active transport
- Against concentration gradient & consumes ATP
- Primary active transport
- Secondary active transport
- Against concentration gradient & consumes ATP
Microfilaments
- Appearance
- Function
- Appearance
- Thin protein filaments (6 nm diameter), often in parallel bundles or dense networks in the cytoplasm
- Function
- Support microvilli and plasma membrane
- Involved in muscle contraction and other cell motility, endocytosis, and cell division
Micrometer
One-millionth of a meter, one-thousandth of a millimeter
Microtubules
- Appearance
- Function
- Appearance
- Hollow protein cylinders (25 nm diameter) radiating from the centrosome
- Function
- Hold organelles in place
- Form axonemes of cilia and flagella, centrioles, basal bodies, and mitotic spindles
- Enable motility of cell parts
- Form trackways that direct organelles and macromolecules to their destinations within a cell
Microvilli*
- Increase a cell’s surface area
- Move substances from extracellular to intracellular surfaces
- Positioned in a vertical position; required for functionality
- Not motile
- Widespread sensory roles (hearing, equilibrium, taste)
Mitochondria*
- Organelle specialized in synthesizing ATP
- “Powerhouse of the cell”
- Energy is not made here, but it is extracted from organic compounds and transferred to ATP, primarily by enzymes located on the cristae
- Contains its own nucleic acid, called mDNA (received from maternal chromosomes)
- Has a double unit membrane
- Outer membrane (matrix) makes contact with cytoplasm
- Inner membrane is folded (cristae_)_
- Intermembrane space is located between the inner and outer membrane of the mitochondria
Nuclear Pores
Allow for information to be moved from the nucleus out into the cytoplasm
Nucleus Structure Identification*


Nucleus*
- Description
- Nuclear envelope role
- Nucleoplasm components
- Controls and regulates the activities of the cell and carries the genes
- Directs protein synthesis by allowing contact with rough ER and ribosomes
- Largest organelle
- Can be multinucleate (skeletal muscle cells) or anuclear (RBC at full maturity)
- Components
- Nuclear envelope
- Neucleoplasm which has:
- Nucleoli: ribosome production
- Chromatin: composed of DNA & protein
List the destructive organelles*
- Lysosomes
- Peroxisomes
- Proteosomes
Organelles*
- Description
- Types and examples
- Internal structures found in the cytoplasm
- Carry out specialized metabolic tasks
- Two types: membranous & nonmembranous
- Membranous
- ER
- Golgi complex
- Lysosomes
- Mitochondria
- Nucleus
- Peroxisomes
- Nonmembranous
- Ribosomes
- Centrosomes
- Centrioles
- Basal bodies
- Membranous
Osmolarity
- Osmotic concentration
- The basis of unit concentration is milliosmoles per liter
Osmosis*
- Flow of water from one side of a selectively permeable membrane to the other
Osmotic Pressure*
- Pre-set pressure amount that stops or prevents osmosis from occurring
Passive transport
- Diffusion
- Osmosis
- Filtration
Peripheral Proteins
- Those on the inner face
- Typically anchored to a transmembrane protein as well as to the cytoskeleton
Peroxisomes*
- Description
- Function
- Destructive organelle that uses molecular oxygen to oxidize organic molecules
- Produces hydrogen peroxide (H2O2); two nontoxic products
- Catalase lowers the energy required to allow H2O2 to produce water and oxygen
- Is an anion with a negative charge
- Can only identify the chemical structure. Unable to determine if a cell is desired or undesired
- Functions
- Neutralize free radicals
- Detoxify alcohol, other drugs, and a variety of blood-borne toxins
- Breakdown fatty acids into acetyl groups for mitochondrial use in ATP synthesis
Plasma membrane
(aka cell membrane & plasmalemma)
- Description
- Function
- Controls the passage of materials into and out of the organelles and the cell as a whole
- Selectively permeable phospholipid bilayer
- Intracellular face
- Intercellular space is between the two membrane layers
- Extracellular face
- Amphiphilic: Consists of a phosphate group and 2 fatty acid tails
- Function
- Prevents escape of cell contents
- Regulates exchange of materials between the cytoplasm and extracellular fluid
- Involved in intercellular communication
- Defines the boundaries of the cell
- Governs its interactions with other cells
Plasma Membrane Identification


Proteosomes*
- Eliminates proteins no longer needed
- Takes a folded (tertiary) protein and unfolds it, making it nonfunctional
Pseudopods
- Cytoplasm-filled extensions of the cell varying in shape from fine, filamentous processes to blunt fingerlike ones
- Change continually; can retract, lengthen, etc.
- Example: Amoeba
Plasma Membrane
Receptors
- Bind chemical signals to surface proteins and transports them into a cell
- Usually specific for one particular messenger
Reverse Osmosis
- When mechanical pressure overrides osmotic pressure
- Drives water through a membrane against its concentration gradient
Ribosomes*
- Description
- Functions
- Locations
- Contain protein & RNA
- Vary by location & number
- Functions
- Synthesize polypeptides
- Interpret the genetic code
- Locations
- rER
- Nucleus
- Cytoplasm
Scanning Electron Microscope
(SEM)
Produces dramatic 3D images at high magnification and resolution, but can only view surface features
Second Messengers
- A chemical that is produced within a cell (such as cAMP) or that enters a cell (such as calcium ions) in response to the binding of a messenger to a membrane receptor, and that triggers a metabolic reaction in a cell
Simple Diffusion
- The net movement of particles from a place of high concentration to a place of lower concentration as a result of their constant, spontaneous motion
Tonicity*
- Description
- Solution types
- The ability of a solution to affect the fluid volume and pressure in a cell
- Solution types:
- Hypotonic
- Hypertonic
- Isotonic
Transcytosis
- Macromolecules are transported across the interior of a cell
- Macromolecules are captured in vesicles on one side of the cell, drawn across the cell, and ejected on the other side
- Isn’t always to our benefit; hepatitis, polio, AIDS viruses trick our cells into engulfing them by receptor-mediated endocytosis, thus exploiting this mechanism to establish infection
Transmembrane Proteins
- Pass completely through the phospholipid bilayer
- Have hydrophilic regions in contact with the water on both sides of the membrane
- Have hydrophobic regions that pass back and forth through the lipid
Transmission Electron Microscope
(TEM)
- Using a beam of electrons in place of light, the TEM enabled biologists to see a cell’s utlrastructure, a fine degree of detail extending to the molecular level
- The most important thing about a microscope is resolution, not magnification