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