lesson 6

Question 1

molecular composition of cell membranes

Answer 1

carbohydrates on outer surface of plasma membrane form a sugar coat (glycocalyx)=> provides protection and facilitates cell-cell recognition

Question 2

phospholipids are amphipathic

Answer 2

polar hydrophilic heads
nonpolar hydrophobic tails
held together by non-covalent interactions

Question 3

phospholipid bilayers provide selective permeability

Answer 3

small. nonpolar molecules(O2, Co2, N2)
small uncharged polar molecules (H2O) ethanol)
large, uncharged polar molecules (glucose, amino acids)
Ions (Cl, K, Na)

Question 4

fluid mosaic model

Answer 4

molecules in the memrbane cn move around
membrane has lots of different proteins scattered all over it
helps explain how the cell membrane is flexible, how it controls what goes in and out of the cell, and how it can send signals and interact with other cells.

Question 5

passive transporters

Answer 5

carry out facilitated diffusion
bind and transport specific molecule

Question 6

active transport

Answer 6

utilize energy to create and/or maintain a concentration gradient
molecules are transported or pumped up against their concentration gradient
use energy from ATP hydrolysis to power movement

Question 7

endocytosis

Answer 7

allows eukaryotic cells to ingest “larger” material from extracellular environment
3 types:
pinocytosis (cell drinking)
receptor-mediated endocytosis
phagocytosis (cell eating)

Question 8

pinocytosis

Answer 8

nonselective uptake of water and macromolecules
constant inward budding of plasma membrane to form endocytic vesicles

Question 9

receptor-mediated endocytosis

Answer 9

receptor protein binds specific molecule (target)
receptor and target are collected in clathrin-coated vesicles
provides selective uptake of necessary molecules

Question 10

phagocytosis

Answer 10

selective engulfment of another cell
ex: wbcs on foreign cells