Cell theory
1. All living things are made up of cells |
unicellular or multicellular |
2. Cells are the smallest and most basic unit of life |
prokaryotic or eukaryotic |
3. All cells come from pre-existing cells. |
Prokaryotic or Eukaryotic
Prokaryotic |
no nucleus |
Eukaryotic |
has nucleus |
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no membrane bound organelles |
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membrane bound organelles |
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division process is binary fission |
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division process is mitosis |
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unicellular |
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unicellular or multicellular |
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cell wall made of peptidoglycan |
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in fungi or plants with cell walls made of chitin or cellulose |
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smaller cells |
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larger cells |
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bacterial cells |
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animal or plant cells |
all cells have cell membrane, cytoplasm, ribosomes, genetic material (DNA or RNA)
Organelles
Cell (Plasma) Membrane |
Phospholipid bilayer that surrounds the cell to control what goes in and out of the cell |
Cytoskeleton |
Network of threadlike fibers made of proteins to give the cell shape, move organelles around, provide structural support for animal cells |
Cytoplasm |
jelly-like substance mainly made up of H2O that holds everything in place and provides solution for chemical reactions to take place in |
Nucleus |
genetic material that's surrounded by a nuclear membrane with nuclear pores that control what goes in and out that protects the DNA that controls the activities of the cell |
Nucleolus |
inside the cell that makes mRNA which makes ribosomes |
Ribosomes |
located on the Rough ER and floating in cytoplasm that make proteins in a process called translation |
Rough Endoplasmic Reticulum |
Hugs the nuclues and has ribosomes on it that makes proteins |
Smooth Endoplasmic Reticulum |
has no ribosomes and is attached to the Rough ER that makes lipids (membranes), destroy toxins (liver), and regulates calcium (muscles) |
Golgi Apparatus |
folded membrane that gets vesicles of protein from ER to process, sort, and ship proteins where needed |
Vesicles |
"mini-cart" that transports proteins around the cell |
Lysosomes |
Contains enzymes that break down the dead stuff and apoptosis |
Vacuoles |
small and numerous in animal cells but one large one in plants cells that act as a storage |
Centrioles/Centrosomes |
made of microtubules that happen in cell division helping cells divide by pulling chromosomes apart |
Cilia |
shorter, more numerous, like tiny oars (hairs) that move fluid across cell surface |
Flagella |
longer, fewer (tail) that move entire cell |
Mitochondria |
inner membrane and matrix (fluid) where cellular respiration happens (breaks down food to release energy as ATP) |
Chloroplast |
grana (stacks) and stroma (fluid) where photosynthesis happens (converts energy from sun to energy in sugar) |
Cell Wall |
Provides structural support and protection for bacteria, plant and fungi cells. Bacteria's made with peptidoglycan. Plant's made with cellulose. Fungi's made with chitin. |
Peroxisomes |
membrane-bound organelles primarily involved in lipid metabolism and the conversion of reactive oxygen species |
Animal, Plant, Prokaryotic cells
Plant Cell:
chloroplast
central vacuole
cell wall
Animal Cells:
cilia and flagella
centrioles
lysosomes
Bacterial Cells
capsules
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Cell membrane
Phospholipid Bilayer: amphipathic
- hydrophilic heads
- hydrophobic tails
Fluid Mosaic Model
membrane is a fluid structure with "mosaic" of various proteins embedded/attached to bilayer |
phospholipids provides fluidity and elasticity |
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proteins and other molecules embedded in membrane |
Structure of Cellular Membrane
main components |
phospholipids and proteins |
other important molecules |
cholesterol and carbohydrates |
Proteins
Functions |
transport, enzymatic activity, signal transduction, cell to cell recognition, intercellular joining, attachment to cytoskeleton and extracellular matrix |
Integral Proteins |
embedded in |
Peripheral Proteins |
attached to surface |
Cholesterol
at warm temperatures |
restrains the movement of phospholipids and reduces fluidity |
at cool temperatures |
maintains fluidity by preventing tight packing |
Carbohydrates
cell to cell recognition |
cell's ability to distinguish one type of neighboring cell from another |
membrane carbohydrates |
interact with the surface molecules of other cells, facilitating cell to cell recognition |
Selective Permeability
Allows some materials, but not all to go through |
can easily pass: small, non polar, nonionic hydrophobic, neutral molecules and H2O |
cannot easily pass: large (must use vesicles), polar (must go through proteins), ionic, hydrophillic |
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Cellular Transport
Concentration |
# of molecules of a substance in a given volume |
Concentration Gradient |
differnce in concentration (mass) of a substance from one location to another |
Passive or Active Transport |
Homeostasis
the need for an organism to maintain and regulate constant or stable internal conditions |
Growth and homeostasis are maintained by the constant movement of molecules across membranes. |
Passive Transport
Molecules moving DOWN their concentration gradient from HIGH to LOW with NO ENERGY until EQUILIBRIUM is reached |
Simple Diffusion |
The spreading out of molecules |
ion channels |
transport proteins allow ion to flow from a high to low concentration |
Facilitated Diffusion |
transport protein (channel or carrier) helps to facilitate the diffusion of molecules |
aquaporins: tunnel that allows water to go through the membrane |
Osmosis |
Simple diffusion of water across a semipermeable membrane |
Hypertonic solutions = more solutes, less water; water moves out of cell to SHRIVEL |
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Hypotonic solutions = less solutes, more water; water moves into the cell to SWELL/BURST |
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Isotonic Solution = equal solutes and water; cell STAYS THE SAME |
Active Transport
molecules moving AGAINST the concentration gradient from LOW to HIGH concentration |
Molecular Pumps |
Cell uses energy to pump molecules across a membrane through a protein channel (sodium potassium pump and proton pump) |
Cotransport |
single ATP-powered pump that transports solute indirectly |
Exocytosis |
cell uses energy to export materials out of the cell with a vesicle |
Endocytosis |
cell uses energy to import materials into the cell with a vesicle |
Phagocytosis = cell "eating" (cell engulfs solids into vesicle and digests them) |
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Pinocytosis = cell "drinking" (cell engulfs liquids into vesicle and digests them) |
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SA:V Ratio
Formulas |
Surface Area: 6 (lw) |
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Volume: lwh |
Steps to find SA:V |
1. calculate SA |
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2. calculate V |
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3. Divide SA by V |
As cell size increases, the SA:V ratio decreases and the cell becomes less efficient at moving things in and out of the cell
= cell must stop growing or dividing
Cell size
Why are cells small? |
To maintain a larger surface area to volume ratio. The smaller the cells are, the faster and more efficient things can go in and out of the cell. |
Water Potential
Ψ = ΨS + ΨP |
ΨS: solute potential |
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ΨP: pressure potential |
ΨS = -iCRT |
i: ionization constant |
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C: concentration (M) |
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R: pressure constant (0.0821 liters bars/mole K) |
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T: temperature in Kelvin ( oC +273) |
Osmotic Potential |
the potential of H2O moving from hypotonic solutions to hypertonic solutions (High water potential to low water potential) |
Turgor Pressure: When a plant cell is placed in a hypotonic solution and gains a lot of water, the cell wall presses back on the cell membrane to prevent the cell from bursting.
Osmoregulation
the control of water balance |
organisms without cell walls that live in hypertonic or hypotonic environment |
Osmoregulation maintains water balance and allows organisms to control their internal solute composition/water potential. |
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