ap bio unit 2

Cards (64)

  • prokaryotes, plants, and animals have:
    • plasma membrane
    • ribosomes
    only prokaryotes and plants have:
    • cell wall
    only plants and animals have:
    • membrane bound organelles
    • nucleus
    only animals have:
    • centrioles
  • the smaller the cell, the greater the SA:V ratio, allowing substances to diffuse into and out of the cell more efficiently
  • how organisms increase SA:V ratio:
    • fish- gills to increase oxygen intake
    • elephants- elephant ears to increase heat diffusion (get heat OUT of body)
    • mitochondria- cristae, inner folds to produce more energy at a faster rate
    • intestines- villi on the outside to absorb nutrients in the small intestine
  • why are marine mammals so huge in terms of SA:V ratio:
    • marine mammals are warm-blooded
    • ocean water is cold
    • increased size decreases SA:V ratio, therefore causing LESS HEAT lost to environment (good)
  • compartmentalization in prokaryotic vs. eukaryotic cells:
    • prokaryotic: few compartments
    • eukaryotic: many compartments that divide lysosomes, the ER, the golgi complex, and vacuoles
  • endomembrane system organelles:
    • nuclear membrane
    • rough ER
    • smooth ER
    • golgi
    • lysosomes
    • vesicles
    DOES NOT include:
    • mitochondria
    • chloroplasts
    • peroxisomes
  • endosymbiotic theory:
    • eukaryotic cells arose from a prokaryote engulfing another prokaryote cell
  • endosymbiotic theory evidence:
    • have their own circular DNA
    • replicate themselves through binary fission
    • use their own ribosomes to produce their own proteins (go through transcription and translation)
    • have 2 membranes (outer one is a vestige of an endocytotic vesicle)
  • nucleus: stores and protects genetic information/DNA
    • DNA is wrapped around histone proteins to form chromosomes
    • chromatin are the spread out version of DNA
    • nucleolus: assembles ribosomes
    • nuclear membrane: separates chromosomes from cytoplasm
    • nuclear pores: allow molecules to enter/leave nucleus
  • ribosomes: particles composed of ribosomal RNA and protein
    functions:
    • read a genetic message encoded in a sequence of mRNA
    • translate that message into a sequence of amino acids that make up the primary structure of a protein
    • free ribosomes float in the cytoplasm
    • bound ribosomes are connected to the rough ER
    • all ribosomes start out as free, but through protein targeting, they migrate to the ER to become bound and get transported to the lysosome, golgi, or membrane
  • mitochondria: converts food energy into ATP
    key structures:
    • chromosome/DNA (also ribosomes)
    • inner membrane: highly folded (increases SA), has membrane-embedded enzymes and proteins that make ATP
    • matrix (cytoplasm): enzymes for the krebs cycle
    • intermembrane space: electron transport chain
    • outermembrane space: vestige of endosymbiosis
  • ER: an interconnected series of channels found between the nuclear membrane and golgi body in eukaryotic cells
    rough ER: has ribosomes, synthesizes proteins
    smooth ER: lacks ribosomes, synthesizes lipids, detoxifies the cell, metabolizes carbs
    • the liver contains LOTS of smooth ER because it is responsible for alcohol detoxification
  • golgi complex: series of membrane-bound flattened sacs (flattening increases SA)
    • receives vesicles through the cis face from the rough and smooth ER, and chemically modifies the contents (usually proteins)
    • packages modified proteins into vesicles that are sent out through the trans face to lysosomes, the cell membrane, or exported from the cell
  • lysosomes: membrane-bound organelles that contain hydrolytic enzymes
    • only found in animal cells
    • carry out intracellular digestion
    • recycle damaged, worn-out, or excess organelles and molecules
    • play a key role in apoptosis (programmed cell death)
  • cytoskeleton: dynamic network of protein fibers
    • enables cells to move materials and organelles
    • enables cells to move their membranes (endocytosis, amoeboid movement)
    • microfilaments: made of protein actin, muscle contraction, helps form cleavage furrow during animal cell division
    • intermediate filaments: made of protein keratin, reinforcement of shape and position of organelles in cell
    • microtubules: made of protein tubulin, assist in the separation of chromosomes during cell division, important components of cilia and flagella (structures that aid the movement of particles)
  • centrosome: the organelle (with 2 centrioles)
    function:
    • creating spindle fibers for separating chromosomes during mitosis and meiosis
  • central vacuole: only in PLANT cells
    • functions as water storage
    • storing and releasing needed macromolecules
    • isolating waste products
    • maintaining turgor pressure
  • plant cell wall: composed primarily of cellulose (polysaccharide)
    major function:
    • pressure vessel that prevents over-expansion in response to inward water flow (osmotic pressure, the minimum amount of pressure needed to stop a solution from allowing pure solvent to flow through a semipermeable membrane)
    • primary component of wood and water-conducting tubes in plant stems
  • phospholipid structure (amphiphatic):
    • hydrophobic/nonpolar tail
    • hydrophilic/polar head
    • held together by glycerol
    • hydrophobic tails face inward toward nonpolar environments
    • hydrophilic heads face outward toward polar environments
    • stabilized by weak bonds (van der waal bonds) between the tails
  • fluid mosaic model:
    • fluid because components are moving laterally within the plane of the phospholipid bilayer
    • mosaic because it is composed of a variety of pieces such as proteins, cholesterol, and carbs (glycoproteins and glycolipids)
  • diffusion: the movement of molecules from an area of high concentration to an area of low concentration
    • happens spontaneously (relies on the KINETIC energy in the diffusing molecules)
    • molecules flow DOWN their concentration gradients
  • two forms of passive transport:
    • simple diffusion: small nonpolar molecules like CO2, N2, and O2
    • steroid hormones and fats
    • facilitated diffusion: polar molecules and ions can't diffuse across a phospholipid bilayer
    • requires protein channels: transmembrane proteins that only let specific molecules or ions pass
  • active transport:
    • pumping a molecule or ion up its concentration gradient
    • lower concentration to higher concentration
    • requires energy on the part of the cell (usually ATP to ADP to power the pumping process, but also the electron flow)
  • bulk transport:
    • endocytosis: cells taking in substances from the outside by engulfing them in a vesicle derived from the membrane
    • exocytosis: cells dump the contents of vesicles (waste products) outside of the cell
    • both require ENERGY and the involvement of the cytoskeleton
  • membrane potential: an electrical charge across a membrane that creates voltage differences
    • is created by pumping ions across their membranes
    • ex. chloroplasts and mitochondria create electrochemical gradients that generate ATP (creates the -70 mV charge across nerve cell membranes)
  • osmosis: diffusion of WATER from low to high solute concentration (from hypotonic to hypertonic)
    • hypotonic: higher percentage of water, less solute
    • hypertonic: lower percentage water, more solute
  • osmosis in plants:
    • in hypertonic solutions: water leaves the cell, loses turgor pressure (pressure exerted by fluid in cell that presses the cell membrane against the cell wall), membrane peels away from wall (plasmolysis), vacuole shrinks, plant wilts
    • in hypotonic solutions: water flows into the cell, turgor pressure increases, vacuole expands
  • osmosis in animal cells:
    • in hypertonic solutions: water leaves the cell, cell shrinks
    • in hypotonic solutions: water flows into the cell, cell bursts
  • plant cells can survive hypotonic and isotonic solutions, while animal cells can only survive isotonic solutions
  • structure of leaf stomata:
    • stomata (plural) are pores on the underside of leaves
    • each stoma (singular) is formed by 2 guard cells
    • with sufficient water, they buckle outward, creating a pore that allows CO2 to enter the leaf for photosynthesis, but which also allows water vapor to escape
    • stomata can close in response to environmental cues such as water stress
  • water potential: a measurement of water's tendency to move from one place to another
    • adding solute decreases water potential
    • pressure increases water potential
    • water flows from areas of higher to lower water potential
    • hypotonic = high water potential
  • formula for water potential:
    • water potential = solute potential (adding solute to water DECREASES water potential) + pressure potential (adding pressure INCREASES water potential
    • water moves from HIGH water potential to LOW water potential (hypotonic to hypertonic)
  • cholesterol, a type of lipid that is embedded in the membrane, helps minimize the effects of temperature on fluidity
    • at low temperatures, it increases fluidity
    • at high temperatures, it decreases fluidity
  • phagocytosis: form of endocytosis in which large particles are transported INTO the cell
    • used by a macrophage to engulf a pathogen
    • the food vacuole will later fuse with the lysosome to break that engulfed particle down to its basic components
  • pinocytosis: form of endocytosis in which the cell takes in small amounts of extracellular fluid
    receptor-mediated endocytosis: form of endocytosis in which receptor proteins are used to capture a specific target molecule that comes in low concentrations
    • flu viruses, diphtheria, and cholera toxin all use this type of endocytosis
  • Suppose a certain type of molecule were to be removed from the blood by receptor-mediated endocytosis. What would happen if the receptor protein for that molecule were missing or defective?
    • The target molecule would no longer be pulled out of the blood, so it might start building up to abnormally high levels. In fact, this is exactly what happens in the disease known as familial hypercholesterolemia
  • peroxisomes: houses enzymes involved in oxidation reactions, which produce hydrogen peroxide (H2O2) as a by-product
    • DOES NOT receive vesicles from the golgi
  • chloroplasts: thylakoids are in stacks called grana (singular = granum)
    • photosynthesis location
  • glycoprotein: protein with carb attached
    glycolipid: lipid with carb attached
  • integral membrane proteins: at least one hydrophobic region that anchors them to the core of the phospholipid bilayer
    • transmembrane proteins: extends all the way across the membrane