Chapter 3 Review

cell theory

cells are the basic unit of life and have a primary responsibility to contribute to homeostasis

3 main parts of human cells

plasma membrane, cytoplasm, nucleus

integral membrane proteins

embedded in the membrane (ex. channel proteins that selectively allow things to pass)

peripheral membrane proteins

on the outer surface of the lipid bilayer, sometimes attached to the surface of an integral protein

functions of membrane proteins

transport, cell recognition, receptor and ligand, anchors for cell structures, enzymes

types of transport across the plasma membrane

passive (simple, facilitated diffusion, osmosis), active (active transport, endocytosis, exocytosis)

simple transport (diffusion)

molecules move from a higher to lower concentration (ex. oxygen and carbon dioxide easily pass)

facilitated diffusion

use protein channels and transport mechanisms to help large, polar, ionic molecules to pass

osmosis

diffusion of water through a semi-permeable membrane down its concentration gradient

osmolarity

concentration of solutes in a solvent, high osmolarity means high solute and low water

isotonic

same osmolarity inside and outside the cell (no net water movement)

hypertonic

outside of the cell has higher osmolarity (water leaves the cell = shrinking)

hypotonic

outside the cell has lower osmolarity (water enters the cell.= swelling)

vesicular transport

no membrane carriers, needs ATP

endocytosis

bringing molecules into the cell, the pinched off portion becomes an independent vesicle

exocytosis

cell exporting materials using vesicular transport, vesicle membrane becomes part of the cell membrane (how digestive enzymes and hormones are secreted)

membrane potential

K+ can enter and leave, once K+ inside = K+ outside, this is established

cytoplasm

composed of organelles and cytosol

endomembrane system

ER, golgi, vesicles = set of 3 major organelles that form a system inside the cell

endoplasmic reticulum

system of channels continuous with nuclear membrane covering nucleus and composed of lipid bilayer

rough ER

membrane dotted with embedded granules (ribosomes), good for protein synthesis

smooth ER

no ribosomes, synthesis of lipids + phospholipids + steroids, stores and regulates Ca++, metabolizes carbs

golgi apparatus

sorting, modifying, shipping products that come from the rough ER and produces lysosomes

lysosomes

contain digestive enzymes that breakdown several organic compounds

peroxisomes

specialized lysosomes, deal with toxins and located in liver cells

ribosomes

site of protein synthesis, made of 2 ribosomal RNA units around mRNA and followed by protein synthesis

mitochondria

energy transformer of the cell *muscle and neural cells are packed with mitochondria*

cytoskeleton

fibrous protein that provide structural support for cells + critical for mobility, reproduction and transport of substances (made of microfilaments, microtubules, intermediate filaments)