Chp 6-7: Cell Structures and Functions
microscopy
Nucleus
Membranes
Cytoskeleton
cell fractionation is a process of breaking up cells and centrifuging them at different speeds to separate different organelles
large organisms have more cells, keep volume but retain intake from the environment with a larger surface area
EMs are better for images of specific organelles
electron microscopes use an electron beam
to see into or the surface of a specimen
light microscopes pass light through a specimen
and a series of lenses to create an image
nuclear lamina- array of protein filaments, lines envelope, maintains shape
encloses dna in the form of chromosomes, made of dna chromatin complex
membrane is covered in pores and ribosomes so dna can enter/exit and be synthesized
nucleolus- mass of fibers than synthesizes rRNA to create ribosomes
nuclear envelope is a double membrane that encloses the nucleus
ribosomes carry out protein synthesis
membrane enclosed; contains most of the genes in a eukaryotic cells
cells have free ribosomes suspended in the cytosol and bound ribosomes attached to the ER or nuclear envelope
smooth ER aids in metabolism, enzymes detoxify drugs and poisons, stores calcium ions
golgi apparatus receives transport vesicles (cis side, facing ER), organizes and modifies them, sends them out to their respective membrane(trans side)
lysosome- membranous sac carrying enzymes, assist in digesting food particles (phagocytosis)
rough ER is directly connected to the nuclear membrane, houses ribosomes, lumen helps form glycoproteins, sends out transport vesicles
vacuoles- large vesicles, derived from ER/ golgi, solution inside differs from cytosol
ER(endolasmic reticulum) is an extensive membrane system mad up of cisternae,
food vacuoles contain food to be used as energy for the cell(protist)
the endomembrane system is a interconnected membrane system that assists protein transport/modification
contractile vacuoles pump excess water out of the cell(animalia)
Power Sources
inner membrane folds into cristae, enclosing the mitochodrial matrix
both organelles have a double layer of membrane with space between membranes
mitochondria do cellular respiration, use oxygen to drive the generation of ATP
both organelles have their own dna and ribosomes(drives endosymbiote theory), as well as cellular dna and ribosome
endosymbiont theory- eukaryotic ancestors at some point engulfed mitochdria/chloroplast ancestors, eventually incorporating them into their own cell
Florescence reveals specific molecules with florescent dyes or antibodies, causing substances to emit light
Confocal creates a single plane, uses a laser to "optically section" and eliminate blurriness in thick samples (capturing different layers can create a 3d image
Differential interference contrast uses optical modifications to exaggerate density (image appears 3d)
Deconvolution reconstructs an image from multiple planes using software that makes a 3d image
Phase-contrast amplifies variations in density to enhance contrast
Super-resolution lights up individual molecules and record their position to make them clearer
Brightfield uses normal light to cause contrast in an image
(May be aided by dye for visibility)
scanning electron microscopes make a 3d image of the surface of a cell
transmission EM make a thin cross section image of the inside of a structure
can manipulate the plasma membrane to form vacuoles/vesicles
microtubules aids in motility, makes up contrioles (9-3), flagella and cilia (9-2)
motor proteins transports membrane vesicles along a line
support and maintain the cells shape
microfilaments used in muscle contraction, changes in cell shape, division of cells
a network of fibers extending throughout the cytoplasm
intermediary filaments anchor nucleus/organelles, form nuclear lamina, exist after a cell dies
membrane proteins/
transport
glycoproteins may act as identification tags for other cells
intercellular joining- may form junctions with other cells
may act as signal transuction, recieving signal molecules
microfilaments/elements of the cytoskeleton may bind to membrane proteins
proteins can act as enzymes on the surface of a membrane
transport proteins may act as a selective barrier, may hydrolyze ATP
fluid mosaic model- protein molecules floating in a fluid phospholipid bilayer
channel proteins have a hydrophilic channel that molecules/ions us to pass the membrane
most membrane proteins are amphipathic, exist in phospholipid bilayer
aquaporins pass water
membranes are made of phospholipids, which are amphipathic and filter what comes into the cell from its environment
carrier proteins hold onto passengers and shuttle them through the membrane
Comparison: Eukaryotes VS
Prokaryotes
both cells have ribosomes
all cells are surrounded by a plasma membrane, enclosing cytosol and acting as a selective barrier for nutrients
eukaryotes have a membrane bound nucleus; prokaryotes have a nucleoid, centralized area where dna is not bound
only prokaryotes have fimbriae and pili
both can have flagella
central vacuoles contains inorganic ions and water, can enlarge to allow a cell to grow without using up resources (plants)
chloroplasts are the sites of photosythesis, turning solar energy into chemical energy , drives the synthesis of organic compounds
contains stacked membranous system of thylakoids, grouped into granum; fuid surrounding them is call stroma
peroxisomes- specialized metalbolic compartment bound by a single membrane; contain enzymes that remove hydrogen atoms and add then to o2, forming h2o2
Both have cytoskeletons
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passive transport uses diffusion, movement of particles so they spread out into available space(goes down concentration gradient)
one solute will spread out to a empty space, then reach equlibrium; two solutes will diffuse down their own concentration gradients
osmosis- diffusion of water through a selective membrane
tonicity is the ability to cause a cell to gain or lose water; isotonic being a solution that causes no change in water content
hypotonic solutions have less solute, causing the cell to lyse; hypertonic solutions have more solute, causing the cell to shrink
active transport uses energy to pump a solution across a membrane
sodium-potassiums pump pump ions against their concentration gradient
electrogenic pumps generate voltage
proton pumps pump h+ out of a cell
contransport couple ions to assist one in making its way across a membrane