CHapter 3 Flashcards
plasma membrane
Provides cell with structural support, means of communication with its surroundings and other cells, and cell identification surrounds each cell, isolating its internal structures and processes from external environment; surrounds cell and isolates its internal structure; exterior; system of sugars; phospholipid bilayer
cytoplasm
gel in between plasma and nucleus
consists of:
cytosol- – intracellular fluid; site of many important chemical reactions
organelles- ; serve to separate potentially damaging chemical reactions from surrounding cell structures (compartmentalization)
cytoskeleton- creates and maintains shape; holds organelles in place; provides means of transportation for substances within cell
nucleus
contains DNA which makes protein and RNA; enclosed in nuclear envelope
In order for plasma membrane to form an effective barrier between ECF and cytosol, (molecules that make up the phospholipid bilayer) must have what two key properties:
Molecules must have parts that interact with water in both fluid compartments without falling apart
Molecules must have parts that repel water, keeping ECF and cytosol separated
must have polar (hydrophilic) and nonpolar section that must be hydrophobic
amphiphilic
have both a phosphate group (hydrophilic polar head) facing each fluid compartment and two fatty acids (hydrophobic tails) that face one another forming a water-resistant barrier; phospholipid is amphiphilic
what’re the 3 basic parts of a cell?
cytoplasm, nucleus, and plasma membrane
integral proteins
span entire plasma membrane; type of membrane protein
peripheral proteins
found only on one side of plasma membrane or other; type of membane protein
enzymes
speed up chemical reactions; vital to maintaining homeostasis
ECF
extracellular fluid
Structure function core principle
Cells vary widely in size and structure to enable them to better perform specialized functions
do red blood cells have a nucleus?
no
what does chromatin condense into?
46 chromosomes
can small uncharged nonpolar molecules go thhrough the phospholipid bilayer easily?
yes
functions of the membrane proteins (5)
- carry and transport other substances
- signal transduction have a particular site will allow substance/chemical to bind which will change shape of site which will cause a cascade of other reactions
- enzymes
- structural support
- conserve/hold together particular cells
selectively permeable
, allowing certain molecules to cross it while prohibiting passage of other molecules; critical to survival of cell; phospholipid is sp
how can a substance move across a plasma membrane?
some do not require imput of energy (passive transport mechanisms); other processes do require energy (active transport processes)
how to determine if a substance will move across the pm by active transport or passive?
Type of substance
Plasma membrane permeability to substance
Concentration of substance in cytosol and ECF
Concentration gradient
basic force that drives many types of passive transport
simple diffusion
mostly nonpolar solutes like oxygen, carbon dioxide, lipids, and hydrocarbons; pass straight through phospholipid bilayer without need for membrane protein; no energy oxygen move high concentration to low
diffusion
movement of solute molecules from high to low concentration; moving down or with its concentration gradient until equilibrium is reached
facilitated diffusion
involves charged or polar solutes such as ions and glucose; cross phospholipid bilayer with help of a membrane protein (carrier or channel)