Unit 4
The Traditional Cell Theory (Thank you Mr. Microscope!)1. All living things are made of
one or more cells.2. Cells are the basic units of
structure & function in organisms.
3. All cells arise from existing cells.
Modern Cell Theory1. Energy flows within cells2. Cells have DNA that is passed
on to new cells during cell division
3. Cells of similar species are made of basically the same chemical compounds
Organization of OrganismsUnicellular
Example - AmoebaMulticellular
Example – HumanCells Tissues Organs Systems Organism
Same processes needed for survival
How big are cells?Limited by ratio of SA:V
Need large surface areaNeed small volume
Cells will divide or change shape to stay small!
Calculating surface area & volume of a cube
But how small is small?Metric System
But how small is small?http://learn.genetics.utah.edu/content/begin/c
ells/scale
Types of cellsProkaryote
Lacks a nucleus and other membrane bound organelles like chloroplasts & mitochondria
Example – bacteriaEarth’s first & most abundant cells
Typically small
Types of cellsEukaryote
Has a nucleus & other membrane-bound organelles
Example – plant or animal cellArose from prokaryotes
Cell MembraneAKA Phospholipid bilayer
Cell MembraneCharacteristics
Polar heads, non-polar tailsHydrophobic vs. hydrophilicFluid mosaic model – parts are not rigidly fixed in place
Flexibility b/c of polarity
Crossing the Cell MembraneSEMI-PERMEABLE or SELECTIVELY PERMEABLE
Some things can pass…But not everything.Protects cell from harmful substances but requires a lot more energy to function
Crossing the Cell MembraneCell membrane proteins
Integral vs. peripheralChannelsReceptorsMarkers
Type of Cells
Prokaryotes & Eukaryotes have…DNACell membraneCytoplasmCytoskeletonRibosomes
Organelles of EukaryotesNucleus
Nucleolus, nuclear envelope w/ pores
Organelles of EukaryotesEndoplasmic Reticulum
Rough vs. smooth
Organelles of EukaryotesGolgi Apparatus
Organelles of EukaryotesLysosomes
Organelles of EukaryotesMitochondria
Organelles of Plant CellsChloroplastsCell WallCentral Vacuole
So what about human cells?Humans are animalsWe have LOTS of different types of cells (muscle, nerve, bone, etc.) with different functions
Different cells have different functions because they have different numbers of organelles – cell specialization
Example – muscles have lots of ____
Transport of SubstancesPassive vs. Active TransportVocabulary
Concentration gradient – difference in concentration across a space
Equilibrium – concentration is equal across a space;
Equilibrium is DYNAMIC, not static
DiffusionMovement of a substance from high to low concentration until equilibrium is met
VIDEOCan be influenced by temperature
Facilitated DiffusionStill high to low concentration but uses integral “carrier” protein and/or channel
OsmosisMovement of water from high to low concentration through a semi-permeable membrane until equilibrium is met
Semi-permeable – only certain things can pass through
Osmosis SituationsSo what would happen if I put a cell into a solution with a HIGHER solute concentration?
What about putting a salty red blood cell into pure water?
Active TransportMovement of substances against concentration gradient from low to high concentration
Endocytosis & ExocytosisLarge particles in & out of cell