active transport , cotransport Flashcards

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1
Q

what is active transport

A

-The movement of molecules and ions through a cell membrane against the concentration gradient using energy from respiration.
-Requires ATP and carrier proteins

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2
Q

What is active transport used for

A

-Uptake of glucose and amino acids in the small intestine
-Absorption of mineral ions by plant roots
-Excretion of hydrogen ions and urea by kidneys
-Exchange of sodium and potassium ions in neurons and muscle cells.

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3
Q

when is bulk transport used

A

-When extremely large substances need to be moved across a cell membrane

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4
Q

What is endocytosis

A

-Endocytosis is the bulk transport of material INTO the cell, and can be split into three processes: phagocytosis, pinocytosis and receptor-mediated endocytosis.

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5
Q

What is exocytosis

A

-Exocytosis is the bulk transport of material OUT of the cell – essentially the reverse of endocytosis.

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6
Q

Details of active transport

A
  1. Transport is through carrier proteins spanning the cell membrane.
  2. Molecule binds to the receptor complementary in shape of protein.
  3. ATP binds to the carrier protein from inside the cell and it is hydrolysed into ADP + Pi
  4. This causes the carrier proteins to change shape and release the molecule to other side
  5. The phosphate ion is then released and the protein returns to its original shape.
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7
Q

What is co-transport

A

-Co-transporters use concentration gradient of one molecule (Na+) to move another molecule against its concentration gradient (glucose)

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8
Q

What are the 2 section of small intestine

A

-duodenum = most digestion

-ileum = absorption of nutrients & water

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9
Q

Factors which affect the rate if absorption

A

-Folded membrane/microvilli s o large surface area (for absorption)
-Large number of carrier proteins so fast rate (of absorption)
-Large number of mitochondria so make more ATP by respiration

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10
Q

Transport of sodium ions and glucose

A

-Na+ ions leave epithelial cell and enter blood by active transport via carrier proteins using (the hydrolysed ) ATP
-So Na+ concentration in cell is lower than in lumen which maintains a gradient
-Sodium/Na ions enter by facilitated diffusion;
-Glucose absorbed with Na ions against their concentration gradient

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