Cellular Anatomy and Cellular Anatomy and Physiology: Physiology:

Chapter 3Chapter 3

The Cellular Basis of The Cellular Basis of Life:Life:The cell is the basic structural

and functional unit of lifeThe function of an organism

(humans) is dependent upon the collective functions of the cells

Continuity of life depends on cells

Cells: The Body’s Cells: The Body’s Chemistry LabsChemistry LabsCells: The Body’s Cells: The Body’s Chemistry LabsChemistry Labs BIO -

CHEMISTRY life - chemistry

Cell Function: organizing and integrating chemicals

Cellular Anatomy: Cellular Anatomy: OverviewOverview

Generalized CellGeneralized Cell Cells come in a

variety of shapes and sizes

We study a “generalized” cell

This is the Nucleus and Rough Endoplasmic Reticulum…

Terms to KnowTerms to KnowTerms to KnowTerms to KnowPlasma Membrane:

Compartmentalizes H2O, Regulates molecular movement in and out of cell

Cytoplasm:Intracellular region cytosol + cytoskeleton +

organelles

Some Key OrganellesSome Key Organelles..Some Key OrganellesSome Key Organelles..Nucleus: Contains DNA and

Controls synthetic activity of the cellMitochondria: Responsible for

oxidative metabolism in generating ATP

Ribosomes: Sites of protein synthesis

Others: Endoplasmic Reticulum, Golgi, Vesicles (vacuoles)…

CELLULAR CELLULAR PHYSIOLOGY: PHYSIOLOGY:

Overview Overview

Key “Life Functions”Key “Life Functions”

Of the CellOf the Cell

Membrane Control of Membrane Control of Cellular HomeostasisCellular HomeostasisMembrane Control of Membrane Control of Cellular HomeostasisCellular Homeostasis

DiffusionOsmosisMediated

TransportEndocytosis

& Exocytosis

Cellular HomeostasisIntracelluar vs. Extracellular

Cellular HomeostasisIntracelluar vs. Extracellular

ProteinsGlycogenK+

Na+Ca++Cl-

Selective Permeability: SomeThings are selected for in, othersFor out: Depends on Channels – Depends on Channels – Membrane Channels that is…Membrane Channels that is…

It Depends…Not on It Depends…Not on Channels but on GradientsChannels but on GradientsIt Depends…Not on It Depends…Not on Channels but on GradientsChannels but on Gradients

O2

CO2

GlucoseUreaAmino AcidsMore on this when we look

closely at molecular movement across membranes

Cell Functions = Life Cell Functions = Life Functions:Functions: Reproduce Grow Adapt Transform Energy

MetabolismRespiration

Excretion Contribute to the function of the whole

Growth, Reproduction and Growth, Reproduction and Adaptation: Protein SynthesisAdaptation: Protein Synthesis

TranscriptionTranslationPost-Translational

ModificationsMitosis and Meiosis…

Transforming Energy:Transforming Energy:ATP HomeostasisATP Homeostasis

Anaerobic MetabolismConverting fuels to ATP in the

Cytosol – without oxygenAerobic Metabolism

Converting fuel by-products to ATP in the Mitochondria – using oxygen

Take “2”: Review and Take “2”: Review and Draw Cell OrganellesDraw Cell Organelles:Take “2”: Review and Take “2”: Review and Draw Cell OrganellesDraw Cell Organelles:CytoplasmEndoplasmic ReticulumGolgi ApparatusRibosomesCytoskeleton: microtubules,

filaments, intermediary filament

Plasma Membranes – Plasma Membranes – Selectively Permeable Selectively Permeable BarriersBarriers

Plasma MembranesPlasma MembranesPlasma MembranesPlasma MembranesSelective

“barrier” – regulating intracellular homeostasis

Interface for intercelluar interaction

Membrane Membrane Specializations:Specializations:Microvilli: “Little shaggy hairs”

Fingerlike projections to increase the surface area of the membrane

Part of the membraneCilia: “eyelashes”

NOT part of the membrane, but protein fibers extending from the cell

“tail wagging” to propel substances across the cell surface

Membrane CompositionMembrane CompositionPhospholipidsImbedded Proteins:

*Channels, Carriers, Signal Receptors, Enzymes, Support

Cholesterol, Sugar Residues

PhospholipidsPhospholipids“Glycerol, 2 fatty acid “tails”,

Phosphate “head” Dual Nature”:

*Both Polar and Non-Polar Non-Polar Ends “group”

away from water:

Phospolipids Have a Polar Phospolipids Have a Polar Head and a Non-Polar TailHead and a Non-Polar Tail Polar Heads:Hydrophilic –

“water loving” The heads face the watery inside

and outside of the cellNon-Polar Tails: Hydrophobic

– “water hating”The tails hide from the water…

Phospholipid Bi-LayerPhospholipid Bi-Layer

Outside of Cell

Inside of Cell

+ -Heads

Heads

Tails

Selective PermeabilitySelective PermeabilityLarge molecules, and many

ions cannot cross the lipid barrier

Other ions/ small lipid soluble molecules are “allowed” to cross

Water molecules generally move with ions or larger molecules

Concentration GradientsConcentration Gradients= Potential Energy= Potential Energy

A difference in [molecule] concentration (high vs low) across the membrane = concentration gradient

Concentration Concentration GradientsGradientsCreate a “Potential” energy

sourceMolecules will always move

from high concentrations to low concentrations

Question: How does the concentration of “scent” molecules in a room change with time?

EquilibriumEquilibriumBalanceEqual

concentration of molecules on both sides of the membrane

Equal movement in and out of cell

Terms: The stuff that Terms: The stuff that movesmovesSolvent: predominant

material (H2O)Solute: molecule dissolved in

the solventConcentration Gradient: of

solutes in a solvent

Terms: The way stuff Terms: The way stuff movesmovesDiffusion: Solute molecules

move across membraneFacilitated Diffusion: By

carriersOsmosis: Solvent (H2O) moves

Active Transport: ATP Energy

Passive DiffusionPassive DiffusionSolutes move “downhill” along

or with a concentration gradientRequires no ATP energySmall Molecules freely

permeable: O2, CO2, urea etc

And Now: A Diffusion Demonstration!

OsmosisOsmosis

Solvent (H2O) moves “down” a (H2O) concentration gradient

Only Water Moves !Water moves to “disperse”

crowded solute molecules, when they are “trapped”

Osmotic Terms: Solute Osmotic Terms: Solute ConcentrationsConcentrations ( (Outside cellOutside cell))

Isotonic: Solute concentration equal on both sides of membrane

Hypotonic: Solute concentration less than inside cell

Hypertonic:Solute concetration more than inside cell

Cells and Solutions:Cells and Solutions:When the “bathing When the “bathing solution” isn’t isotonicsolution” isn’t isotonic

Memory Aids…Distilled Memory Aids…Distilled Water is HypotonicWater is Hypotonic“Gee Doc,

that’s a SWELL HYPOdermic!”

Cells Swell in Hypotonic solutions: Lyse

And…The Dead Sea is And…The Dead Sea is hypertonichypertonic

“I get HYPER when my jeans SHRINK!”

Cells Shrink in Hypertonic solutions: Crenation

Isotonic solutions keep everyone happy

Challenge! Cystic Fibrosis Challenge! Cystic Fibrosis is an Osmosis Problemis an Osmosis ProblemCheck out this web site on the cell

http://www.usd.edu/~bgoodman/cell-ebration.html

What single membrane protein is dysfunctional in people with Cystic Fibrosis?

Why can we say that CF is an “OSMOSIS” problem?

Facilitated DiffusionFacilitated DiffusionCarrier Mediated: Temporary

“binding”Moves “downhill” with

concentration gradientGlucose is “carrier mediated”NO ATP required

Active TransportActive TransportRequires metabolic energy

(ATP)Moves molecules “uphill”

against a concentration gradient

Na+/K+ Pumps

Assignment: Create a table describing the movement of molecules across plasma membranes:

Like so….

Active

Trans

Osm

Fac.

Diff.

Pass.

Diff

Mech. Energy WhatMoves?

Carrier ?

Up/DownGradient?