chapter 3 Flashcards
physical barrier of plasma membrane
physical barrier: encloses the cell, separating the cytoplasm from the extracellular fluid
selective permeability of plasma membrane
determines which substances enter or exit the cell
communication of plasma membrane
plasma membrane proteins interact with specific chemical messengers and relay messages to the cell interior
cell recognition of plasma membrane
cell surface carbohydrates allow cells to recognize each other
steps of protein function
1) transport
2) receptors for signal transduction
3) enzymatic activity
4) cell-cell recognition
5) attachment to the cytoskeleton and extracellular matrix
6) cell to cell joining
active transport
requires transport proteins that combine specifically and reversibly with the transported substances
in primary active transport where does the energy come from
the energy to do the work comes directly from hydrolysis of ATP by transport proteins called pumps
primary active transport
hydrolysis of ATP results in the phosphorylation of the pump
sodium potassium pump
the most important example of a primary active transport system
secondary active transport
cotransport
uses a cotransport protein to couple the “downhill” movement of one solute to the “uphill” movement of another solute
vesicular transport
fluid containing large particles and macromolecules are transported across cellular membranes inside bubble-like membranous sacs called vesicle
Lysosomes
Responsible for digesting and breaking down excess of worn-down cell parts
- simple spherical membrane-bound sacs containing powerful digestive enzyme called acid hydrolases
-“suicide sacs”: bears down and recycle unnecessary or dangerous biological chemicals
true or false: Primary active transport is driven by secondary active transport.
false
