Chapter 3: Cells Flashcards
Plasma Membrane
Separates internal metabolic events from the external environment and controls the movement of materials into and out of the cell.
Cell
The basic functional unit of all living things.
Cytoplasm
Made of organelles suspended in the cytosol
Cytosol
A fluid matrix which consists of water and dissolved substances such as proteins and nutrients
Double phospholipid membrane
Has polar hydrophilic heads forming the two outer faces and non-polar hydrophobic tails pointing inside the membrane.
Fluid Mosaic Model
The mosaic nature of scattered proteins within a flexible matrix of phospholipid molecules.
How does the fatty acid makeup influence the fluidity of the membrane?
Saturated fatty acids- pack tightly- more rigid membrane
Unsaturated fatty acids- Bend at their double bonds, not at tightly packed- more flexible
What can and can’t get through a selectively permeable membrane?
Can: Small, uncharged, polar molecules (H20). Hydrophobic molecules (O2, CO2, and lipid-soluble molecules like hydrocarbons)
Can’t: Large Polar Molecules (Glucose), All Ions
Channel Proteins
Intrinsic Proteins, provide open passageways for certain hydrophilic (water-soluble) substances such as polar and charged molecules.
Ion Channels
Allow the passage of ions across the membrane
Gated Channels
Open and close in response to stimuli to allow passage of certain ions.
Carrier Proteins
Bind to specific molecules which are then transferred across the membrane after the carrier protein undergoes a change of shape.
Transport Proteins
Uses energy (in ATP form) to transport materials. Often called Active transport. Sodium-Potassium pump uses ATP.
Recognition Proteins
Give each cell type a unique identification. Helps distinguish between self and foreign cells.
Glycoproteins
Made up of proteins with short, polysaccharide chains that extend away from the surface. Same as recognition proteins
Receptor Proteins
Provide binding sites for hormones or other trigger molecules.
In response to hormone or trigger molecule, a specific cell response is activated.
Adhesion Proteins
Attach cells, provide anchors for internal filaments, give stability to cell.
Cholesterol
Molecules that provide some stability to the plasma membranes of animal cells.
High Temps: Maintains Firmness
Low Temps: Makes Flexible
Organelles
Bodies within the cytoplasm that physically seperate the various metabolic reactions.
Contents of the Nucleus
DNA
Nuclear Envelope
Binds the Nucleus, made up of two phospholipid bilayers
chromatin
DNA which it is spread out within the nucleus as a thread-like matrix
Chromosomes
The DNA when it is condensed into rod-shaped bodies
Makeup of Chromosomes
Before division is made up of two long DNA molecules and various histone (protein) molecules.
Nucleoli
Concentrations of DNA in the process of manufacturing the components of ribosomes.
Nuclear Pores
Passageways for proteins and RNA molecules
Ribosome Subunits
Manufactured in the nucleus and consist of RNA molecules and proteins
Ribosomes
Assembled in the cytoplasm. Made up of two subunits, 60S and 40S to form an 80S ribosome. Assit in gthe assembly of amino acids into proteins
Endoplasmic reticulum
Consists of stacks of flattened sacs that begin as an extension of the outer bilayer of the nuclear envelope.
Rough ER
Ribosomes are present on the rough ER. The rough ER creates glycoproteins by attaching polysaccharide groups to polypeptides as they are assembled by the ribosomes.
Smooth ER
Synthesizes lipids and steroid hormones.
Ex. Liver, removes toxins
Golgi Apparatus
A group of flattened sacs (cisternae) arranged like a stack of bowls.
Collects and modifies proteins and lipids made in other areas of the cell and package them into vesicles for transport.
Lysosomes
Vesicles from a Golgi Apparatus that contain hydrolytic enzymes. They break down food, cellular debris, and foreign invaders.
A low pH favors the activity of enzymes.
Peroxisomes
Break down various substances, including hydrogen peroxide, H2O2, fatty acids, and amino acids. Common in liver and kidney cells.
In Plants, they modify by-products of photorespiration
Mitochondria
Carry out aerobic respiration, a process in which energy (In the form of ATP, is obtained from carbohydrates, fats, and proteins.
Chloroplasts
Carry out photosynthesis. Double Membrane
Microtubules
Made of the protein tubulin and provide support and motility for cellular activities.
Are found in the spindle apparatus, and in flagella and cilia
Intermediate filaments
Provide support for maintaining the shape of the cell
Microfilaments (Actin filaments)
Made of the protein actin and are involved in cell motility. Found in muscle cells and cells that change shape
Flagella
Long, few, and move in a snake-like motion
Cilia
Short, many, and move with a back-and-forth, serpentine movement.
How are cilia and flagella arranged?
Both consist of microtubules arranged in a “9+2” array–nine pairs (doublets) of microtubules arranged in a circle surrounding a pair of microtubules.
Centrioles and Basal Bodies
Act as microtubule organizing centers (MTOCs)
Vacuoles and Vesicles
Fluid filled, membrane-bound bodies
Transport Vesicles
Move materials between organelles or between organelles and the plasma membrane.
Food Vacuoles
Temporary receptacles of nutrients. Often merge with lysosomes, whose digestive enzymes break down the food.
Contractile Vacuoes
Specialized organelles in single-celled organisms that collect and pump excess water out of the cell.
Central Vacuoles
Large bodies occupying most of the interior of many plant cells.
Extracellular Region
The area outside the plasma membrane
Cell Walls
Found in plants, fungi, and many protists.
Provide support
Often made of cellulose, a polysaccharide made of B-Glucose
Extracellular Matrix
The area between adjacent cells.
Found in animals.
Cell Junctions
Serve to anchor cells to each other and provide a passageway for cellular exchange.
Anchoring Junctions
Protein attachments between adjacent animal cells.
Desmosome
An anchoring junction that consists of proteins that bind adjacent cells together, providing mechanical stability to tissues
Tight Junctions
Tightly stitched seams between animal cells.
The junction completely encircles each cell, producing a seal that prevents the passage of materials between the cells.
Communicating Junctions
Passageways between cells that allow the transfer of chemical or electrical signals
Gap Junctions
Type of communicating junction.
Narrow tunnels between animal cells.
Prevent cytoplasmic proteins and nucleic acids from mixing, but allow the passage of ions and small molecules.
Plasmodesmata
Narrow Channels between PLANT cells.
A narrow tube of ER, surrounded by cytoplasm, passes through the channel.
Differences between plant and animal cells
Plant cells have cell walls, chloroplasts, and central vacuoles
Animal cells have centrioles and cheolesterol
Bacteria and archaea are…
prokaryotes
Selectively Permeable Membrane
Allows only specific substances to pass.
Hypertonic
A higher concentrations of solutes
Hypotonic
A lower concentration of solutes
Solvent
Water
Solute
The substance dissolved in water
Isotonic
An equal concentration of solutes
Bulk Flow
The collective movement of substances (solvent and solutes) in the same direction in a response to a force or pressure.
Passive transport
Processes describe the movement of substances from regions of higher concentrations to regions of lower concentrations.
Does not require energy
Simple Diffusion
The net movement of substances from an area of higher concentration to an area of lower concentration.
Osmosis
The diffusion of water molecules across a selectively permeable membrane.
Turgor Pressure
The hydrostatic pressure that develops when water enters the cells of plants and microorganisms.
Plasmolysis
The movement of water out of a cell (by osmosis) that results in the collapse of the cell.
Facilitated diffusion
The diffusion of solutes or water through channel proteins or carrier proteins in the plasma membrane.
Countercurrent Exchange
Describes the diffusion of substances between two regions in which substances are moving by bulk flow in opposite directions.
Active Transport
The movement of solutes against a gradient and requires the expenditure of energy
Vesicular Transport
Uses vesicles or other bodies in the cytoplasm to move macromolecules or large particles across the plasma membrane.
Exocytosis
The process of vesicles fusing with the plasma membrane and releasing their contents to the outside of the cell.
Endocytosis
Describes the capture of a substance outside the cell.
Phagocytosis
“Cellular Eating”
Occurs when undissolved material enters the cell.
Pinocytosis
“Cellular Drinking”
Occurs when dissolved substances enter the cell.
Receptor-mediated endocytosis
A form of pinocytosis, occurs when specific molecules in the fluid surrounding the cell bind to specialized receptors
