Eukaryotic and Prokaryotic Cells PDF

# Eukaryotic and Prokaryotic Cells ## Eukaryotic Cell - Less surface area per unit volume - Harder to exchange inside out - DNA in nucleus ## Prokaryotic Cell - More surface area per unit volume - Easier to get nutrients and energy into cell - Loose DNA - No organelles ## Nucleus - Contains DNA -...

# Eukaryotic and Prokaryotic Cells ## Eukaryotic Cell - Less surface area per unit volume - Harder to exchange inside out - DNA in nucleus ## Prokaryotic Cell - More surface area per unit volume - Easier to get nutrients and energy into cell - Loose DNA - No organelles ## Nucleus - Contains DNA - Nuclear envelope (Double layer) - Nucleolus inside nucleus - Nuclear pores lets things in and out - Chromatin: loosely wound DNA - Ribosomes: tightly wound DNA embedded on the side of the nucleus - Made of rRNA and protein, turns mRNA - None membrane bound ## Vacuole - Large vesicle - Storage of water, turgid structure ## Chloroplasts - Harness energy - Photosynthesis: sun -> carbohydrates - Granum: stacks of thylakoids - Stroma: surrounding fluid ## Mitochondria - Animal energy - Cellular respiration: O2 + fuel -> ATP - Cristae: folds of inner membrane - Ribosomes in matrix ## Endoplasmic Reticulum - Smooth: lipid synthesis, detox, calcium storage - Rough: factory for protein creation, manufactures more membrane - Abundance of ribosomes ## Golgi Apparatus - Shipping and receiving - Molecules are modified before shipping in vesicles - Sacs of digestive enzymes ## Lysosomes - Phagocytosis: cell eating - Autophagy: self eating of cell components ## Extracellular Matrix: Between Cells - Extracellular fluid, complexes of proteins and carbohydrates - Junctions: cells bond together - Tight junctions: no leakages, Desmosomes are molecular velcro, Gap channels: cytosol, water and ions pass through - Plasmodesmata: plant cell channels/ gaps ## Cytoskeleton: Internal Scaffolding for movement - Microtubules: movement; separate chromosomes during cell division - Control beating of cilia and flagella - Hollow, made of tubulin protein, track for motor proteins - Originate from region called centrosome - 9 sets of triplet microtubules - 9 tripletas: flagella and cilia attachments = basal body - Doublets: *extended portion of flagella and cilia* - Dynein attach/ detach, movement ## Centrosome - Microtubule-organizing region ## Intermediate Filaments - Twisted fibrous proteins anchor and structure ## Microfilaments - Muscle contraction - Made of actin protein ## Membrane Proteins - Allows communication with the extracellular environment - Integral: embedded in membrane - Peripheral: loosely attached - Amphipathic: 50/50 hydrophobic and hydrophilic ## Functions of Membrane Proteins: - Transport channels - Receptors for signal transduction - Cytoskeleton attachments - Enzyme activity - Intercellular attachments/ cellular adhesion (CAMS) - Cell-cell recognition ## Active Transport (ATP) - Primary transport: against concentration - Secondary transport: - Uses the *stored* energy from active transport - Pumps ions uphill, ions flow down their concentration gradient through channels and glucose - Vesicular/ bulk transport: molecules move in vesicles, plasma membrane - Endocytosis: bring inside: phagocytosis (cell eating), pinocytosis (cell drinking), receptor mediated (inward motion of pinching) - Exocytosis: take outside ## Passive Transport: - *Simple:* to lower concentration - Diffusion: move till equally and random distribution - Osmosis - *Facilitated:* Aquaporins, channel mediated - Local: - Gap junctions - Cell-cell recognition - Paracrine: local regulation - Target cell close - Synaptic signaling: neurotransmitter diffuse across synapse - *Long Distance:* - Nervous tissues: electricity - Endocrine: blood and hormones - Takes a long time to travel through circulatory system ## Signaling - **3 Stages** - **Reception:** recognize the signaling molecule - Plasma membrane receptor: GPCR (ligand gated), ligand binds to GPCR, G-protein. GTP activates a protein -> GPCR -> signal -> active protein -> Enzyme - Ligand gated ion channel: specific ligand opens channel, allowing molecules to move - Intra cellular receptor: soluble lipids diffuse through membrane -> receptor protein - **Transduction:** convert signal into trigger. Cellular response: relay molecule (second messenger, cAMP activates proteins) - Phosphorylation cascade: shuffling around phosphates groups to activate/ deactivate proteins - **Response:** final trigger - First messenger: GPCR -> GTP -> G-protein -> Enzyme (Adenylyl cyclase). ATP -> cAMP (second messenger). Phosphorylation cascade -> Cellular response ## Metabolism - Energy coupling: using an exergonic process to drive an endergonic one - Inhibition: slowing/ stopping - Competitive: *mimic* substrate to fill in - Non competitive: change active site shape - Allosteric: binds to inactive form, stabilized. Binds to regulatory site, active form stabilized. - Cooperativity: actual substrate binding influences further binding - Feedback inhibition: product turns off the process, changes shape. ## Anabolic and Catabolic - Anabolic: build up, absorbs heat - Catabolic: break down, releases heat ## Thermodynamics - Energy cannot be created or destroyed. - Disorder always increases. - Entropy: disorder/ randomness - Creating order locally increases the entropy of the universe, releasing heat and waste heat created. ## Gibbs Free Energy - AG = Gibbs free energy: available energy for work. - AG = GF - GI - Negative AG: energy released, higher disorder, increase work capacity. - Positive AG: energy absorbed, lower disorder, decrease work capacity. - Spontaneous reaction: no work ## System at Equilibrium - Exergonic: energy released, spontaneous: - Catabolic: AG neg - Final product less potential energy - Endergonic: energy absorbed. - Anabolic: AG pos - Final product more potential energy