Flashcards in CHapter 3 Deck (57):
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
gel in between plasma and nucleus
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
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
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
span entire plasma membrane; type of membrane protein
found only on one side of plasma membrane or other; type of membane protein
speed up chemical reactions; vital to maintaining homeostasis
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?
what does chromatin condense into?
can small uncharged nonpolar molecules go thhrough the phospholipid bilayer easily?
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
-conserve/hold together particular cells
, 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
basic force that drives many types of passive transport
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
movement of solute molecules from high to low concentration; moving down or with its concentration gradient until equilibrium is reached
involves charged or polar solutes such as ions and glucose; cross phospholipid bilayer with help of a membrane protein (carrier or channel)
type of diffusion; when the cell can't reach equilibrium, this happens; it is a passive process in which a solvent (usually water) moves across a membrane; concentration of solute molecules causes water to move down concentration gradient
driving force exerted by solute molecules; causes water molecules to move until equilibrium (no net movement) is reached
from where does water move across the membrane?
Water moves from area with lower concentration of solute (more water molecules) across membrane to area with higher concentration of solute (less water molecules
how does water move across a plasma membrane?
1. Water passes through channel proteins known as aquaporins; primary route for osmosis of water
2. A small amount of water is able to pass through phospho-lipid bilayer directly
way to compare osmotic pressure gradients between two solutions – cytosol and ECF
denoting or relating to a solution having the same osmotic pressure in the inside and outside, especially one in a cell or a body fluid.
solute concentration of ECF is higher than inside cell; more water molecules inside cell than outside; osmotic pressure gradient pulls water out of cell and cell shrinks or crenates; more solute ourside than inside
solute concentration of ECF is lower than inside cell; more water molecules in ECF than inside cell; osmotic pressure gradient pulls water into cell causing the cell to swell and possibly rupture or lyse; less solute outside of cell
what kind of energy does active transport require?
Active transport processes require energy in form of ATP to proceed as solutes move against their concentration gradients from low concentration to high concentration
sodium potassium pump
The process of moving sodium and potassium ions across the cell membrance is an active transport process involving the hydrolysis of ATP to provide the necessary energy.
Electrical potential found across plasma membrane is known as a membrane potential; study of these potentials is called electrophysiology
are cellular machinery with specific functions vital to maintaining homeostasis; some are separated from cytosol by membrane (compartmentalization) while others are not enclosed in a membrane
list membrane bound organelles
: mitochondria, peroxisomes, endoplasmic reticulum, Golgi apparatus, and lysosomes; perform functions that could be destructive to rest of cell
what organelles are not enclosed in a membrane?
ribosomes and centrosomes
what is the function of the mitochondria?
“power plant” of cell; membrane-bound organelles involved in chemical energy production; provide majority of ATP used in cell
mitochondria membrane is double bilayer structure with smooth outer membrane and inner membrane that is highly folded into cristae
produce hydrogen peroxide; break down chemicals and get rid of them
rough ER (FUNCTION)
has ribosomes (protein synthesis);
1. Products enter RER lumen; incorrectly folded polypeptide chains are detected and sent to cytosol for recycling
2. Most proteins that enter RER are for transport out of cell
3. Packages secretory proteins into transport vesicles made of a phospholipid bilayer; sent to the Golgi apparatus for further processing
4. Produces membrane components for membrane-bound organelles and plasma membrane, including integral and peripheral proteins
smooth ER (FUNCTION)
no ribosomes; Stores calcium ions, lipid synthesizers, detoxification
– located between RER and plasma membrane – group of flattened membranous sacs filled with enzymes and other molecules; proteins and lipids from ER are modified, sorted, and packed for export ( to fuse with plasma membrane)
what is the endomembrane system?
process where lipids go from nucleus, to ER, to Golgi
organelles responsible for digestion of worn out cell components or whole cells in some cases; if there's 1 type of acid component missing, it can cause a disease; breaking material down
what is the cytoskeleton made up of? funcion?
help organize other organelles, help cell movement and framework, allows cellular movement
list the cellular extensions of a cell
microvilli. function. location.
f: helps absorb nutrients, help maintain shape, Increase surface area
cilia. function. location.
f: Move in unison to propel substances past the cells
flagella. function. location.
f: Beat in a whiplike fashion propelling entire cell (unlike cilia – propel materials past the plasma membrane
l: sperm cells
DNA is executed by diff types of ____
governing body that directs activities of the other cellular components; largely determines type of proteins and rate at which cell makes them
the nuclear envelope surronds what?
membrane that surrounds nucleoplasm (cytosol-like gel containing many components – water, free nucleotides, enzymes, other proteins, DNA, and RNA)
stretched on DNA; organizes and folds molecule to conserve space
chromatin threads coil tightly and condense into thick structures
identical copies of each chromosome; made in preparation for cell division; connected to one another at region called centromere
List the order that DNA is made to proteins.
Gene expression – production of protein from specific gene
Two processes actually make a specific protein:
Transcription – process where gene for specific protein is copied; creating messenger RNA (mRNA); exits through nuclear pore
Translation occurs in cytosol; mRNA binds with ribosome initiating synthesis of a polypeptide consisting of a specific sequence of amino acids