Chapter 7 Cell Structure and Function Section 7.1- Life is Cellular Section 7.2- Eukaryotic Cell Structure Section 7.3- Cell Boundaries Section 7.4- Diversity of Cellular Life

Section 7.1- Life is Cellular Discovery of Cells Robert Hooke Used light microscope to look at cork cells Cells reminded him of monk cubicles “many little boxes” Called them CELLS

Section 7.1- Life is Cellular Discovery of Cells Anton van Leewenhoek First to observe living cells Invented simple, tiny microscopes

Section 7.1- Life is Cellular The cell theory states that: all living things are composed of one or more cells cells are the basic units of structure and function in an organism cells come only from the reproduction of existing cells

Section 7.1- Life is Cellular Cellular Basis of Life All living things are made of organized parts obtain energy from their surroundings perform chemical reactions change with time respond to their environment reproduce.

Section 7.1- Life is Cellular Prokaryotes Prokaryote cells lack a nucleus and membrane-bound organelles. Have genetic material not contained in a nucleus

Section 7.1- Life is Cellular Eukaryotes Eukaryote cells have a nucleus and membrane-bound organelles

7.4- The Diversity of Cellular Life

Unicellular Organisms Single cell organism Dominate life on Earth

Multicellular Organisms Made up of many cells MO depend on communication and cooperation among specialized cells Cell Specialization Cells develop differently to perform different tasks A cell’s shape reflects its function.

Two Basic Types of Cells Eukaryote Has a nucleus Has organelles Cytoplasm/cell membrane Nucleolus Prokaryote Lacks a nucleus Lacks organelles (ribosomes) Cytoplasm/cell membrane

Cellular Organization In multicellular eukaryotes, cells organize into tissues, organs, organ systems, and finally organisms.

Section 7.2- Eukaryotic Cell Structure

Basic Parts of a Cell

Comparing Cells There are some differences between plant and animal cells There are some similarities

Nucleus “The Brain” DNA, surrounded by nuclear envelope, nucleolus- where ribosomes are made

Ribosomes “The Construction Company” Builds proteins Free floating in the cytoplasm or attached to the ER

Endoplasmic Reticulum “The Highway” (tubes and sacs) Rough Produces phospholipids and proteins Smooth Produces cholesterols

Golgi Apparatus “The Post Office” Receives proteins from ER Modifies, labels and directs proteins to locations in the cell

Lysosomes Specialized organelles Lysosome- “The Killer or Garbage Truck” Breaks down molecules Maintains cell’s health by getting rid of non-functioning parts

Vacuole Specialized organelles Vacuole- “The Storage Center” Stores water, nutrients and waste

Mitochondria “The Power House” Where ATP is produced

Chloroplast Use light energy to make C6H12O6 and O2 Thylakoids Flattened membranous sacs that contain chlorophyll Chlorophyll Pigment that absorbs light and captures light energy for the cell

Cytoskeleton “The Infrastructure” Cell support Microtubule Hold organelles in place Microfilaments Cell movement Intermediate Filaments Maintain internal shape of cell

Section 7.3- Cell Boundaries

Cell Membrane Cell membrane Border Phospholipid bilayer

Cell Membrane Fluid Mosaic Model Proteins embedded in lipid bilayer Cell surface markers, pumps, channels, receptors

Cell Wall rigid layer made of cellulose

Passive Transport What does passive mean? What does transport mean? Movement of substances across a membrane “down” their concentration gradients without using energy

Diffusion Net flow from high conc. to low conc. Driven by kinetic energy (energy of motion)

Diffusion Semipermeable Membrane Down Concentration Gradient Equilibrium “both sides are equal” High [ ] Low [ ]

Osmosis Diffusion of water across a membrane Direction of osmosis into or out of a cell depends on solute concentrations inside and outside the cell Animation of Osmosis

Osmosis- Direction of Osmosis Isotonic Hypertonic Hypotonic Salt is the solute A solute is a substance that dissolves in a solvent

Facilitated Diffusion Diffusion that requires the help of carrier proteins Animation of Facilitated Diffusion

Diffusion Through Ion Channels Ion channels are membrane proteins that allow only specific ions to pass through. Channels can be “open” or “gated” If an ion channel is gated, it can be opened by stretching the cell membrane, a voltage, or a chemical

Active Transport Cell Membrane Pumps Movement in Vesicles

Active Transport What does active mean? What does transport mean? Movement of substances across a membrane “up” their concentration gradients using energy

Cell Membrane Pumps ATP Carrier proteins that move substances from areas of low concentration to areas of high concentration. Requires energy What molecule furnishes the energy to power the pump? ATP

Sodium-Potassium Pump Transports Na+ and K+ 3 Na+ out of cell / 2 K+ into cell

Animation of Sodium-Potassium Pump How Na+/K+ pump works: Animation of Sodium-Potassium Pump

Movement in Vesicles What happens if substances are too large to pass through the cell membrane or carrier protein? What does the prefix endo- mean? What does the prefix exo- mean? What does cyto- mean? What does –osis mean?

Movement in Vesicles Endocytosis Process by which cells ingest what they need. Requires energy Cell membrane folds and pinches off to form a vesicle

Endocytosis 2 Types Pinocytosis Phagocytosis Endocytosis of solutes and fluids Phagocytosis Endocytosis of large particles and whole cells Phagocytes

Movement in Vesicles Exocytosis Process by which cells release unwanted substances. Requires energy Vesicles fuse to membrane to let substances out of cell