Unit 2 AP Bio Study Guide

Cells

The basic structural and functional units of every organism, bound by a plasma membrane, containing cytosol, chromosomes, and ribosomes.

Prokaryotes

Cells without a nucleus, found in the domains Bacteria and Archaea, generally smaller than eukaryotes.

Eukaryotes

Cells with a nucleus and membrane-bound organelles, including protists, fungi, animals, and plants.

Organelles

Membrane-bound structures within eukaryotic cells that perform specific functions.

Endomembrane organelles

Organelles that include the nuclear envelope, endoplasmic reticulum, Golgi complex, lysosomes, vesicles/vacuoles, and plasma membrane.

Energy organelles

Organelles that include mitochondria and chloroplasts, involved in energy production.

Compartmentalization

The division of cellular functions into different organelles, allowing for specialized metabolic reactions and increased surface area for reactions.

Nucleus

The organelle that contains chromosomes and is enclosed by a double membrane called the nuclear envelope.

Ribosomes

Complexes of ribosomal RNA and protein that synthesize proteins; can be free in the cytosol or bound to the endoplasmic reticulum.

Endoplasmic Reticulum (ER)

A network of membranous sacs and tubes involved in synthesizing membranes and compartmentalizing the cell.

Rough ER

The portion of the endoplasmic reticulum that has ribosomes attached, involved in protein synthesis.

Smooth ER

The portion of the endoplasmic reticulum that lacks ribosomes, involved in lipid synthesis and detoxification.

Golgi Complex

An organelle that modifies, sorts, and packages materials received from the ER into transport vesicles.

Lysosomes

Membranous sacs containing hydrolytic enzymes that digest macromolecules and recycle cellular components.

Vacuoles

Large vesicles that store materials; types include food vacuoles, contractile vacuoles, and central vacuoles in plants.

Endosymbiont Theory

The theory that explains the similarities between mitochondria and chloroplasts to prokaryotes, suggesting they originated from engulfed prokaryotic cells.

Mitochondria

Organelles that are the site of cellular respiration, containing a double membrane and involved in ATP production.

Chloroplast

Organelles in photosynthetic organisms that contain chlorophyll and are the site of photosynthesis.

Cytoskeleton

A network of fibers providing structural support, anchoring organelles, and facilitating movement within the cell.

Microtubules

Hollow rod-like structures made of tubulin that assist in cell shape, organelle movement, and chromosome separation during cell division.

Microfilaments

Thin solid rods made of actin that maintain cell shape, assist in muscle contraction, and aid in cell division.

Cellular Metabolism

The set of chemical reactions that occur within a cell, influenced by cell size and material exchange efficiency.

Surface Area-to-Volume Ratio (SA:V)

A critical factor that affects cellular function, where a higher ratio allows for better material exchange.

Plasma Membrane

A selective barrier that regulates the entry and exit of substances, maintaining homeostasis within the cell.

Phospholipids

The fundamental building blocks of the plasma membrane, consisting of a hydrophilic head and two hydrophobic tails.

Membrane Fluidity

The ability of the plasma membrane to remain flexible, influenced by temperature and the presence of unsaturated fatty acids.

Fluid Mosaic Model

A description of the plasma membrane as a dynamic structure with a phospholipid bilayer and embedded proteins.

Integral Proteins

Membrane proteins that are embedded within the lipid bilayer, often involved in transport and communication.

Peripheral Proteins

Membrane proteins that are loosely attached to the membrane's surface, involved in signaling and maintaining cell shape.

Glycolipids

Carbohydrates bonded to lipids in the membrane, contributing to stability and functionality.

Glycoproteins

Carbohydrates attached to proteins, playing a role in signaling and cell recognition.

Cell Wall

A rigid structure surrounding plant cells, providing support and protection, primarily composed of cellulose.

Plasmodesmata

Channels in plant cells that connect adjacent cells, facilitating communication and material transport.

Turgor Pressure

The pressure exerted by water inside the plant cell, maintained by the cell wall and essential for plant health.

Challenges of Larger Cells

Larger cells face difficulties in nutrient intake and waste expulsion due to a decreased SA:V ratio.

Evolutionary Advantage of Smaller Cells

Smaller cell sizes are favored in many organisms for efficient metabolic processes and material exchange.

Osmosis

The movement of water across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration.

Passive Transport

A mechanism that does not require energy input from the cell for the movement of substances.

Cellular Homeostasis

The maintenance of stable internal conditions within a cell, influenced by processes like osmosis.

Tonicity

The ability of an extracellular solution to affect the water balance of a cell based on solute concentration.

Isotonic Solution

A solution where the concentration of nonpenetrating solutes is equal inside and outside the cell, resulting in no net water movement.

Hypertonic Solution

A solution with a higher concentration of nonpenetrating solutes outside the cell, causing water to move out and leading to cell shrinkage.

Hypotonic Solution

A solution with a lower concentration of nonpenetrating solutes outside the cell, causing water to move in and potentially leading to cell swelling or lysis.

Turgor Pressure

The pressure exerted by the fluid inside a plant cell against the cell wall, maintained in hypotonic solutions.

Water Potential

A measure of the potential energy in water that predicts the direction of water movement, combining solute potential and pressure potential.

Solute Potential (𝚿s)

Reflects the effect of solute concentration on water potential, expressed as a negative value.

Pressure Potential (𝚿p)

Represents the physical pressure on a solution, which can be positive or negative.

Water Potential Formula

𝚿 = 𝚿s + 𝚿p, used to calculate the overall water potential of a solution.

Ionization Constant (i)

The number of particles formed from a solute when it dissolves, used in calculating solute potential.

Molar Concentration (C)

The concentration of a solute in a solution, expressed in moles per liter.

Pressure Constant (R)

A constant value (0.0831 liter bars/mol-K) used in the calculation of solute potential.

Temperature in Kelvin (T)

The temperature used in calculations, converted from Celsius (K = 273 + °C).

Water Movement in NaCl Solution

Water diffuses out of a plant cell placed in a higher concentration NaCl solution due to osmosis.

Solute Potential Calculation

The process of determining the solute potential using the formula 𝚿s = -iCRT.

Water Potential in Root Tissue

The comparison of water potential between root tissue and surrounding solutions to predict water movement.

Selective Permeability

The ability of a cell membrane to allow certain substances to pass while restricting others, crucial for maintaining homeostasis.

Phospholipid Bilayer

The structural component of the cell membrane that plays a key role in its selective permeability.

Easily Crossable Substances

Small nonpolar, hydrophobic molecules that can pass through the membrane without assistance, such as hydrocarbons, CO2, O2, and N2.

Difficult Passage

Hydrophilic, polar molecules, large molecules, and ions that require assistance to cross the membrane, like sugars and water.

Passive Transport

A type of transport that does not require energy as substances move along their concentration gradient.

Active Transport

A type of transport that requires energy to move substances against their concentration gradient.

Diffusion

The spontaneous movement of molecules from high to low concentration, moving down the concentration gradient.

Osmosis

The diffusion of water across a selectively permeable membrane from areas of low solute concentration to high solute concentration.

Facilitated Diffusion

A passive transport mechanism that uses transport proteins to help move substances across the membrane.

Channel Proteins

Proteins that provide hydrophilic channels for molecules and ions to pass through the membrane.

Carrier Proteins

Proteins that undergo conformational changes to transport substances across the membrane.

Pumps

Integral proteins that use ATP to transport ions and molecules across the membrane in active transport.

Sodium-Potassium Pump

An electrogenic pump that maintains the electrochemical gradient by pumping 3 Na+ ions out and 2 K+ ions into the cell.

Proton Pump

A pump that transports H+ ions out of the cell, creating a proton gradient used by plants and bacteria.

Cotransport

A mechanism that couples the favorable movement of one substance with the unfavorable movement of another, utilizing energy stored in electrochemical gradients.

Exocytosis

The process of secreting molecules via vesicles that fuse with the plasma membrane, important for neurotransmitter release.

Endocytosis

The uptake of molecules through vesicles formed from the plasma membrane.

Phagocytosis

A type of endocytosis involving the engulfing of large particles to form a food vacuole for digestion.

Pinocytosis

A non-specific endocytosis mechanism for the uptake of extracellular fluid and dissolved molecules.

Receptor-Mediated Endocytosis

A specific uptake mechanism that involves receptor binding for concentrated intake of specific substances.