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43 Cards in this Set
- Front
- Back
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what are some functions of the plasma membrane |
- isolates the cell's contents from the external environment - it regulates the exchange of essential substances - allows communication between cells - creates attachments within and between cells - regulates biochemical reactions |
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indicates that each membrane consists of a mosaic of different proteins that constantly shift and flow within the double layer of phospholipids |
fluid mosaic model
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the fluid portion of the membrane |
phospholipid bilayer |
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what two parts make up phospholipids? |
- a polar, hydrophilic head - 2 non polar, hydrophobic cells |
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water-soluable substances ______ easily pass phospholipid bilayers |
cannot |
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very small molecules such as ___, ____, and ___ ___ as well as larger, lipid-soluable molecules can pass through the phospholipid bilayer |
water, oxygen, and carbon dioxide |
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___ stabilizes membranes, affecting fluidity and reducing permeability |
cholesteral |
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____ are embedded within, or attached to the phospholipid bilayer |
proteins |
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many proteins have attached _____ (____) on their outermost membrane surface |
carbohydrates (glycoproteins) |
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list the 5 types of membrane proteins |
1. receptor proteins 2. recognition proteins 3. enzymatic proteins 4. attachment proteins 5. transport proteins |
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what is the job of receptor proteins |
trigger cellular responses upon binding of specific molecules, such as hormones sent by other chemicals |
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what is the job of recognition proteins |
they are glycoproteins that serve as identification tags on the surface of a cell |
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what are the two types of transport proteins |
- channel proteins - carrier proteins |
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what do channel proteins do |
form channel whose central pores allow specific ions or water molecules to pass through the membrane |
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what do carrier proteins do |
they have binding sites that can temporarily attach to specific molecules on one side of the membrane and then move them through the membrane to the other side |
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what are the two types of movement across the plasma membrane |
- passive transport - energy-requiring transport (active transport) |
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what is passive transport |
is the diffusion of substances across cell membranes down concentration gradients |
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what is energy-requiring (active) transports |
transport that requires the use of cellular energies |
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what is simple diffusion |
substances move down their concentration gradients across a membrane examples: water, oxygen, carbon dioxide, and lipid-soluable molecules |
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what is it called when water soluble molecules like ions, amino acids, and sugars diffuse down their concentration gradients with the aid of channel and carrier transport proteins |
facilitated diffusion |
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list the 3 different osmotic solutions |
- hypotonic - hypertonic - isotonic |
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what does hypotonic mean |
means theres more water outside then inside, cell gains water SHAWN GETS BIGGER |
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what does hypertonic mean |
means theres more water inside than outside, cell loses water SHAWN GETSE SMALLER |
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what does isotonic mean |
means theres equal amounts on both sides, no change in cell volume SHAWN IS JUST RIGHT,like he usually is |
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energy requiring transport includes, ____, ____, and ____ |
active tranport, endocytosis, and exocytosis |
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during ___, membrane proteins use energy to move molecules or ions across plasma membrane ___ their concentration gradients |
active transport, against |
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active proteins are often referred to as ___ |
pumps |
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cells engulf particles or fluids by ____ |
endocytosis |
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particles engulfed by endocytosis are transported within the cell inside ___ |
vesicles |
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what are the 3 types of endocytosis |
- phagocytosis - receptor-mediated endocytosis - pinocytosis |
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what happens during pinocytosis |
"cell drinking" moves liquids into the cell |
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what happens during receptor-mediated endocytosis |
moves specific molecules into the cell |
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what happens during phagocytosis |
"cell eating" moves large particles into the cell |
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____ moves particles out of the cell |
exocytosis |
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cells use energy to dispose of undefeated particles of waste or to secrete substances into the extracellular fluid by ___ |
exocytosis |
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___ attach cells together |
desmosomes |
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___ are found where cells need to adhere tightly together under the stresses of movement |
desmosomes examples: skin, intestine, urinary bladder |
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___ make cell attachments waterproof |
tight junctions |
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what is found where tubes and sacs must hold contents without leaking |
tight junctions examples: skin, urinary bladdes |
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where are gap junctions found? |
in animals |
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where are plasmodesmata found? |
in plants |
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cell-to-cell protein channels allowing for passage of hormones, nutrients, and ions in animal cells are called ___ |
gap junctions |
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plant cells have holes in the walls of adjacent cells forming cytoplasmic connections called ____ |
plasmodesmata |
