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 Theory 1. Energy flows within cells 2. 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 Organisms Unicellular Example - Amoeba Multicellular Example – Human Cells  Tissues  Organs  Systems  Organism Same processes needed for survival

How big are cells? Limited by ratio of SA:V Need large surface area Need 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? ale ale

Types of cells Prokaryote Lacks a nucleus and other membrane bound organelles like chloroplasts & mitochondria Example – bacteria Earth’s first & most abundant cells Typically small

Prokaryotes

Types of cells Eukaryote Has a nucleus & other membrane- bound organelles Example – plant or animal cell Arose from prokaryotes

Prokaryote vs. Eukaryote

Cell Membrane AKA Phospholipid bilayer

Cell Membrane Characteristics Polar heads, non-polar tails Hydrophobic vs. hydrophilic Fluid mosaic model – parts are not rigidly fixed in place Flexibility b/c of polarity

Crossing the Cell Membrane SEMI-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 Membrane Cell membrane proteins Integral vs. peripheral Channels Receptors Markers

Cell Membrane

Type of Cells CELLSEUKARYOTES ANIMALPLANT PROKARYOTES (first cells)

Prokaryotes & Eukaryotes have… DNA Cell membrane Cytoplasm Cytoskeleton Ribosomes

Innards of Cells

Organelles of Eukaryotes Nucleus Nucleolus, nuclear envelope w/ pores

Organelles of Eukaryotes Endoplasmic Reticulum Rough vs. smooth

Organelles of Eukaryotes Golgi Apparatus

Organelles of Eukaryotes Lysosomes

Organelles of Eukaryotes Mitochondria

Organelles of Plant Cells Chloroplasts Cell Wall Central Vacuole

So what about human cells? Humans are animals We 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 Substances Passive vs. Active Transport Vocabulary Concentration gradient – difference in concentration across a space Equilibrium – concentration is equal across a space; Equilibrium is DYNAMIC, not static

Diffusion Movement of a substance from high to low concentration until equilibrium is met VIDEO Can be influenced by temperature

Facilitated Diffusion Still high to low concentration but uses integral “carrier” protein and/or channel

Osmosis Movement 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 Situations So 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 Transport Movement of substances against concentration gradient from low to high concentration

Endocytosis & Exocytosis Large particles in & out of cell