light microscopes: visible light pased through specimen and then through glass lenses which magnifies the image (can study living cells)

electron microscope: focuses beam of electrons through specimen (but can study only dead cells)

scanning electron microscope (SEM): detailed study of surface of specimen by exiciting electrons on it

transmission electron microscope (TEM): aims electron beam through a specimen stained with atoms of heavy metals which enhance electron density in some areas which scatters electrons more to create an image by pattern of transmitted electrons

take cells apart and separate major organelles

instrument used is a centrifuge

results in a pellet (cell contents) at the bottom and the cell fluid at the top 

an organism needs a sufficient surface area to accomodate its volume

as object grows in size, volume increases more than surface area

so a smaller organism with a greater ratio of surface area to volume is ideal 

DNA in nucleoid region

DNA is circular and supercoiled 

bounded by plasma membrane

has a cell wall and capsule (jelly-like outer coating) 

but no membrane bound organelles

no cytoskeletons

divides asexually

may have plasmids (small circular DNA apart from nucleoid)

contains genes

enclosed by nuclear envelope

lined by nuclear lamina (netlike proteins)

DNA organized into chromosomes made of chromatin

contains nucleolus where rRNA is synthesized 

particles made of rRNA and protein

carry out protein synthesis

free ribosomes are suspended in cytosol

bound ribosomeos are attached to outside of endoplasmic reticulum or nuclear envelope

free ribosomes make proteins that function inside the cell, like enzymes that catalyze sugar breakdown 

bound ribosomes make proteins for membranes or for export from the cell (cells that specialize in protein secretion-such as pancreatic cells which secrete digestive enzymes-will have more bound ribosomes)

membranes are part of the endomembrane system

membrane segments are vesicles that transfer particles

includes nuclear envelope, endoplasmic reticulum, Golgi apparatus, lyosomes, various vacuoles, and plasma membrane 

ER is an extensive network of membranes

smooth ER lacks ribosomes

enzymes of smooth ER can metabolize carbohydrates, make lipids (steroids, sex hormones, phospholipids, oils), detoxify drugs by adding OH groups to them, and store calcium ions

rough ER has ribosomes

secrete glycoproteins (proteins with carbohydrates) which depart from ER via transport vesicles

makes its own membrane phospholipids 

where products of ER are modified, stored, and sent

consists of flattened membranous sacs called cisternae

cis face recieves

trans face ships 

receive transport vesicles from ER

vesicles coalensce to Golgi cis face, move through Golgi apparatus, products are refined as needed, and buds off from trans face 

membranous sac of hydrolytic enzymes that an animal cell uses to digest macromolecules

work best in acidic environments

phagocytosis: eat by engulfing food particles

autophagy: digests damaged organelle 

compartments 

food vacuoles

contractile vacuoles pump excess water out

plant cells have a central vacuole enclosed by tonoplast membrane and stores organic compounds 

sites of cellular respiration

smooth outer membrane

inner membrane has infoldings called cristae

inner membrane divides mitochondrian into two internal compartments:

intermembrane space

mitochondrial matrix 

member of plastid family

consists of interconnected stacks called thylakoids stacked into a granum

fluid outside thylakoid is the stroma

contain chlorophyll which absorb light for photosynthesis 

metabolic compartment

transfers hydrogen from various substrates to oxygen to produce hydrogen peroxide 

break fatty acids

detoxify alcohol

compartmental structure contains an enzyme that converts hydrogen peroxide back to water 

network of fibers extending throughout the cytoplasm for support, motility, and reguation

microtubule: hollow tubes consisting of tubulin, thickest

functions in maintaining cell shape, cell motility (cilia and flagella), chromosome movements in cell division, and organelle movements 

grow out from centrosome which have centrioles

cilia and flagella are locomotive appendages (9+2 pattern) anchored in the cell by basal body

motor protein dynein "walks" on microtubules 

microfilaments: strands of actin, thinnest

bears tension, muscle contraction, cell motility (pseudopodia), cleavage furrow 

actin and myosin in muscles 

intermediate filaments : fibrous proteins supercoiled

anchorage of nucleus and certain other organelles, formation of nuclear lamina 

extracellular structure of plant cells that protects it, prevents excessive uptake of water, and holds it up

primary cell wall, middle lamella, and secondary cell wall

connected by junctions called plasmodesmata (similar to gap junctions) where water, solutes, and cytosol can pass freely, forming a continuum of plant cells

tight junctions: membranes of neighboring cells tightly pressed against each other, binds two cells together

desmosomes: rivets that fasten cells together into strong sheets

gap junctions: communicating junctions that provide cytoplasmic channels from one cell to another, consists of a pore where small molecules can pass through 

ECM contains glycoproteins like collagen which forms strong fibers outside cells within a network of proteoglycans

fibronectin binds to cell surface receptor proteins called integrins

shows arrangement of phospholipids and proteins in cell membrane

shows proteins embedded in or attached to the bilayer of phospholipids

exhibits selective permeability, allows some substances to cross more easily than others

consists of amphipathic phospholipids that form the phospholipid bilayer 

integral proteins penetrate hydrophobic core

peripheral proteins are loosely bound to surface

glycolipids and glycoproteins function in cell to cell recognition 

hydrophobic (nonpolar) molecules (hydrocarbons, carbon dioxide, and oxygen) can dissolve in lipid bilayer easily

hydrophilic molecules like glucose and water pass throught the bilayer slowly

transport proteins enable hydrophilic substances to enter the cell without contacting the lipid bilayer 

functions include:

transport

enzymatic activity

signal transduction

cell-cell recognition

intercellular joining

attachment to cytoskeleton 

diffusion is the tendency for molecules of any substance to spread out evenly into available space

substances diffuse down their concentration gradient (from higher concentration to lower concentration)

diffusion of a substance across biological membrane is passive transport for the cell does not have to expend energy

transport proteins such as channel proteins can provide a gate for molecules to travel past the lipid bilayer, this is called facilitated diffusion

examples are ion channels or gated channels

movement of water across a selectively permeable membrane

 tonicity is the ability of a solution to cause a cell to gain or lose water

hypertonic solutions have more solute and less water

a cell in this solution will lose water and shrivel

hypotonic solutions have less solute and more water

a cell in this solution will fill up with water and lyse

in an isotonic solution, the net movement of water is the same

plant cells prefer a hypotonic environment, because their cell wall resists too much water uptake, this causes the plant to become turgid (very firm)

in a hypertonic solution, plants will lose water and become plasmolyzed

plants become flaccid in isotonic solutions

movement of molecules against its concentration gradient

sodium-potassium pump (pumps sodium out with ATP, allows potassium to enter the cell, maintains resting potential)

voltage across a membrane is its membrane potential (negative inside the membrane, positive outside)

molecules diffuse down their electrochemical gradient

a transport protein that generates voltage is an electrogenic pump such as proton pump

a substance pumped across a membrane can do work as it moves back across the membrane by diffusion, this is cotransport

phagocytosis: cell engulfs a particule by wrapping pseudopodia around it and packaging it in membrane-enclosed sac

pinocytosis: cell takes in droplets fluid

receptor-mediated endocytosis: ligands (any molecule that binds to a receptor) bind to recptor proteins which stimulate them to form a vesicle that is ingested