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Active Transport
• Sometimes cells must move against the
concentration gradient– From areas of low concentration to
areas of high
– This requires the cell’s energy “ATP”
– Done by transport proteins called
“pumps”
– Larger molecules can also be
transported across the membrane by
endocytosis and exocytosis
Active Transport Lab
• Background Information: Congo red
is a biological dye, that diffuses
easily into the cell, like water
• This diffusion does not require
energy
• You are using yeast cells, that I woke
up by adding water and sugar- they
are currently alive …
Lab Results
1. Macroscopically… which sample is darker?
2. Microscopically…. Which cells have absorbed
the dye?
3. Are the (not boiled) yeast cells alive?
4. Are the boiled yeast cells alive?
5. Which cells moved the dye via active
transport?
6. Of the cells that moved the dye…Did they
move the dye in or out?
7. If active transport was used to move the dye,
out via what mechanism did the dye get in?
Active
Transport
Endocytosis
Phago-
Exocytosis
Pino-
Protein
Pumps
Endocytosis
• Endocytosis taking material into the cell by
means of infoldings, of the cell membrane.
– The pocket is called an ENDOSOME
– Large molecules, clumps of food, and even whole cells
can be taken up in this way.
– Two examples phagocytosis and pinocytosis.
Phagocytosis
• Phagocytosis means “cell
eating.”
• In phagocytosis, extensions
of cytoplasm surround a
particle and package it
within a food vacuole. The
cell then engulfs it.
• Amoebas use this method
of taking in food.
PINOCYTOSIS
• “Cell drinking”
• cells take up liquid from the
surrounding environment. Tiny
pockets form along the cell
membrane, fill with liquid, and pinch
off to form vacuoles within the cell.
• Occurs continuously and in almost all
cells
EXOCYTOSIS
• Many cells also release large
amounts of material from the
cell.
• Vesicles in the cell travel to the
cell membrane, fuse with it, and
expel the contents to the ECF.
• http://www.maxanim.com/physiology/
Endocytosis%20and%20Exocytosis/E
ndocytosis%20and%20Exocytosis.ht
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