BIOL 220 - Chapter 3: Cellular Form & Function

- organisms are composed of cells
- simplest unit of life (structural and functional)
- the structure and function of an organism is due to the properties of their cells
- cells come from preexisting cells (mitosis and meiosis)
- cells from all species exhibit biochemical similarities
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- organisms are composed of cells
- simplest unit of life (structural and functional)
- the structure and function of an organism is due to the properties of their cells
- cells come from preexisting cells (mitosis and meiosis)
- cells from all species exhibit biochemical similarities
What is the Cell Theory?
egg cell, and some fat cells (100μm)
What is the largest cell?
neurons (<1m), muscle cells (<30cm)
What is the longest cell?
There are certain sizes that cells do not get above because they can't survive at that certain size and shape
Why are cells limited to how large they can be?
- volume & surface area
- cells need nourishment and waste removal
- cells need oxygen, unless its an anaerobic bacterial cell
- require membrane area to transport nourishment and waste removal
What are some limits that affect a cell's size?
- Tubules, fibers, passages (cytoskeleton)
- Cytosol (fluid)
What components are in the Cytoplasm?
- Proteins and lipids
- Cholesterol
- Few Carbohydrates
What makes up the plasma membrane?
- Cytoplasm
- Plasma Membrane
- Organelles
What are the 3 basic components of a cell?
the membrane is effectively choosy about what can go through the membrane
What does selectively permeable mean?
Proteins
______________ help dictate and facilitate what can be transported across the membrane in either direction, whether it's coming inside, or it's getting sent to the outside of the cell.
- Filtration - Diffusion - OsmosisWhat are some examples of Passive Transport?- vesicular transport and active transportWhat are some examples of Active Transport?passive is always going DOWN a gradient, active requires ATP (energy) and typically sends things against their concentration gradientWhat is the difference between passive and active transport?FiltrationMembrane Transport: - pressure involved (hydrostatic - fluid puts pressure on surroundings) - no pressure = no circulation - Ex. Blood capillariesDiffusionMembrane Transport: - high to low concentration - rate of diffusion depends on temperature, weight, steepness, and surface area - increased temp = increased rate - permeabilityOsmosisMembrane Transport: - water distribution/balance - movement of water towards an area whether there is a high solute concentration - towards higher non-permeable solute concentration - aquaporin density can be dynamicextracting salt from waterWhat is an example of reverse osmosis?energyOsmosis is passive so in order to reverse it, you have to use ___________Carrier-Mediated TransportMembrane Transport: - cell membrane necessary - solute binds to carrier - carrier changes shape - solute released on other side - very rapid - carrier saturationthe person has so much glucose that it's going to overwhelm the proteins and all the proteins are going to be busy transporting glucose. But there's still going to be some of it that is not able to be transported just because there is so much of it, so the excess glucose is excreted in the urine.Explain Carrier-Mediated Transport in Diabetes?Uniport- transports one type of solute - from external environment to internal environmentSymports- cotransport of 2+ solutes - transports in same directionsAntiports- counter transport of 2+ solutes - transport in different directions - ex. Na+K+ pumpFacilitated Diffusion- transports down concentration gradient - no ATP neededPrimary Active Transport- Sending solutes against (up) concentration gradient - Requires ATP - Ex. Ca²⁺ pump, amino acid pumpsSecondary Active Transport- Indirect use of ATP - relies on other pumps using energy - requires a different protein to use that energy, not itself - Ex. Na+ pumps in kidney tubule cellsNa+/K+ pumpPump: - maintains steep gradient - negative charged membrane potential - produces enough heat to use half of daily caloriesEndocytosismeans into cellExocytosismeans out of cellVesicular Transport- large/many contents, fluid droplets - uses motor proteins and requires ATP to facilitate movementPhagocytosisType of Endocytosis: - engulfing particles (phagosomes) - pseudopods - Lysosomes aiding, digesting and breaking down whatever was brought into the cellPinocytosisType of Endocytosis: - engulfing all cells - deals with droplets and not solid components - taking in ECF dropletsReceptor-MediatedType of Endocytosis: - selective - particles bind to receptorsExocytosis- discharging material - Ex. insulin to tissue, sperm enzymes, milk sugars - linking proteins at membrane - membrane forms dimple - fuses with secretory vesicleTranscytosis- Transport of particles through cells - Ex. insulin, blood-brain barrierRough ER- Sacs covered in ribosomes - Produces phospholipids and mem. Proteins that are either going to​ go to the cell membrane or they're going to be released outside the cell. - More prevalent in cells producing large amounts of protein - E.g. Pancreas, liverSmooth ER- No ribosomes - Detoxification - Most prevalent in kidney and liver cells - Store Ca²+ (e.g. muscle cells) which is necessary for muscle contractionRibosomes- protein and RNA - Found in cytosol, nuclear envelop, rough ER - read mRNA and assemble proteins through a process called translationLysosomes- package of enzymes - break down (hydrolyze) proteins, nucleic acids, carbohydrates, and phospholipids - Ex. White blood cells digest bacteriaMitochondria- Synthesize ATP - Double membrane - mtDNA - Endosymbiotic Theory - Arose from endocytosed bacteria