A solution in which the concentration of solutes is greater than that of the cell that resides in the solution
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Isotonic solution
A solution in which the concentration of solutes is equal to that of the cell which resides in the solution
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Hypotonic solution
A solution in which the concentration of solutes is less than that of the cell that resides in the solution
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Water diffuses from...
Hypotonic to hypertonic
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Osmosis
Diffusion of free water across a selectively permeable membrane
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Smaller cells have a higher...
surface area to volume ratio (ex. 12:1)
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Smaller cells have a more...
efficient exchange of material with the environment
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As cells \________ in volume the relative surface area \_________
increase; decreases
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Why aren't cells smaller than they already are?
Cells need room for organelles
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Amphipathic
Molecules that contain both hydrophilic and hydrophobic properties (phospholipids)
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Fluid mosaic model
Model that describes the arrangement and movement of the molecules that make up a cell membrane
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At high temperatures, cholesterol \_________ cell membrane fluidity
decreases
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At low temperatures, cholesterol \__________ cell membrane fluidity
increases
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Passive transport
Movement of molecules from high to low concentration WITHOUT metabolic energy (ATP)
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The inner surface of transport proteins is...
polar to protect polar molecules that come through
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Diffusion
Free movement of small, nonpolar molecules from high to low concentration (ex. N2, O2, CO2)
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Facilitated diffusion
Movement of larger, polar, and/or charged molecules from high to low concentration through transport proteins; Allows for hydrophilic molecules to pass through membranes (ex. glucose, urea, K⁺, Na⁺, Cl⁻)
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Water potential
The physical property predicting the direction in which water will flow, governed by solute concentration and applied pressure.
Active transport is \______ a concentration gradient
against
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Transfer of energy in protein cotransporters
ATP→proton pump→H⁺ ions→cotransporter→sucrose (moved by cotransporter)
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Free energy
Ability to do work
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Channel proteins
Hydrophilic tunnels in the cell membrane that allow larger, polar, and/or charged molecules to pass through
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Carrier proteins
Membrane structures that change shape to move target molecules from one side of the cell membrane to the other
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Active transport is \___________ not pushed
performed
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There are \____ types of passive transport
2
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Osmolarity
Total solute concentration in a solution
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Tonicity
The measurement of the relative concentrations of solute between 2 solutions (in and out of cell)
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Tonicity can only be in reference to \____ environments
2 (a cell has to be hypo/hyper/isotonic to a solution and vice versa)
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Water moves by...
osmosis
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Glycoproteins
One or more carb attached to a membrane protein
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Glycolipids
Phospholipids with a carb attached (communication)
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Free vs. bound ribosomes
Free: float in cytosol and produce proteins for it Bound: attached to the ER, produce proteins that will be a part of the membrane, or enclosed in it
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Nucleoid
A non-membrane-bounded region in a prokaryotic cell where the DNA is concentrated
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Smooth ER
Lipid synthesis, detoxification, carb metabolism, NO ribosomes on its cytoplasmic surface (liver cells have lots because they host glycolysis and are the site of alcohol detoxification)
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Rough ER
Has ribosomes on its cytoplasmic surface
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Eurkaryotic ribosomes are built in a structure called the...
nucleolus
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Golgi apparatus
Proteins, lipids, and other macromolecules are sent her to be modified by the addition of sugar and other molecules to form glycoproteins
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Absence of a particular lysosomal hydrolytic enzyme can lead to...
storage diseases
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Tay-Sachs disease
When an enzyme used to digest lipids is absent, leading to excessive accumulation of lipids in th ebrain
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Peroxisome
Organelle that contains enzymes that produce hydrogen peroxide as a by-product while performing various functions, such as breakdown of fatty acids and detoxification of alcohol in the liver; also contain an enzyme that converts the toxic hydrogen peroxide by-product of these reactions into water
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Cytoskeleton
A network of fibers that provide support, shape, and mobility
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Types of cytoskeleton fibers
Microtubules, microfilaments, and intermediate filaments
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Microtubules
Constructed from tubulin and help in cell division and are in cilia and flagella
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Microfilaments
Constructed from actin and help in muscle contraction
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Intermediate filaments
Constructed from keratins (proteins) and help in shape and position of organelles
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Plants cells do not have...
centrioles
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The surface-area-to-volume ratio affects the ability of a cell to maintain \______________ between its internal and external environment
homeostasis
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Plasmolysis
Collapse of a walled cell's cytoplasm when the cell is in a hypertonic solution and water leaves
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Endocytosis
Process in which substances are brought into the cells by the enclosure of the substance into a membrane-created vesicle that surrounds the substance and escorts it into the cell (used by immune cells called phagocytes)
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Exocytosis
Process in which substances are exported out of the cell when a vesicle escorts the substance to the plasma membrane, causes it to fuse, and ejects the substance outside
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Pinocytosis
Process of bringing in droplets of extracellular fluid via tiny vesicles
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Phagocytosis
Cell takes in large particles
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Types of endocytosis
Phagocytosis, pinocytosis, and receptor-mediated endocytosis
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Receptor-mediated endocytosis
Specialized type of pinocytosis that moves specific molecules into a cell due to the budding of specific molecules with the receptor sites on the cell membrane
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Organelles in prokaryotes
Cell wall, membrane, ribosomes
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Number of \_____________________ can be used to measure rate of endocytosis
vesicles in a cell
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Sodium-potassium pump (ATPase)
A carrier protein that uses ATP to actively transport 3 Na⁺ ions out of a cell and 2 K⁺ ions into the cell to maintain the membrane potential
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If the sodium-potassium pump is shut down...
the sodium and potassium concentration gradients will dissipate, and so will the membrane potential
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Membrane potential
An electrical potential difference (voltage) across their cell membrane
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Benefits of cell compartmentalization
Minimizes competing reactions, provides a favorable environment for specific reactions, and help protect the cell from potentially hazardous products from certain reactions
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Origins of compartmentalization
Prokaryotes formed symbiotic relationships with larger cells (endosymbiosis)
Studied by 30 people
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