the Cell Introduction to

Cell History Robert Hooke – 1665 Anton van Leeuwenhoek - 1673 Observed slices of cork Coined word “cell” Anton van Leeuwenhoek - 1673 First to observe living cells (algae) “animalcules” 1821-1902 Schleiden – plants Schwann – animals Virchow – cell reproduction

Cell Theory All living things are made of one or more cells Cells are the basic units of structure and function in organisms All cells arise from existing cells

Why are cells important? Gas Exchange Eat Make energy (ATP) Build molecules proteins, carbohydrates, fats, nucleic acids Remove wastes Maintain homeostasis Reproduce

Cell Size Can’t be seen with the naked eye Human body = ~100 trillion cells http://www.youtube.com/watch?v=l7kZjdeo0Cs http://www.cellsalive.com/howbig.htm Cell Size Activity

Why so small?! A small cell has a greater ratio of surface area to volume The microscopic size of most cells ensures a sufficient surface area Across which nutrients and wastes can move to service the cell volume 30 m 10 m Surface area of one large cube  5,400 m2 Total surface area of 27 small cubes  16,200 m2

Intro Video https://www.youtube.com/watch?v=URUJD5NEXC8

Cell Types Prokaryotic – single celled organisms that lack a nucleus Eukaryotic – cells with a nucleus and internal compartments

micron = micrometer = 1/1,000,000 meter diameter of human hair = ~20 microns

Common Features Cytoskeleton

Prokaryotic cells Simple, single-celled organisms All have cell walls Many have flagella or pili Some have capsules Ex. Bacteria Prokar yotic flagella Ribosomes Capsule Cell wall Plasma membrane DNA Pili

Eukaryotic cells Nucleus Organelles – differentiated structures within the cell Complex, multi- cellular organisms

Cell Membrane Functions: Structure: Selectively permeable – regulates what goes in and out of cell Protection Controls the internal environment Provides shape Structure: Phospholipid bilayer Transport proteins

Cell Membrane (cont.) Fatty acid tails Phosphate head Hydrophobic – water fearing Phosphate head Hydrophilic – water loving

Fluid Mosaic Model

Transport Passive Transport: particles pass across the cell membrane freely Active Transport: particles cross the cell membrane with the use of energy https://www.youtube.com/watch?v=ufCiGz75DA k

Diffusion Concentration: the amount of a particular substance in a given volume. Substances naturally move from a higher concentration to an area of lower concentration Equilibrium: is reached when a space is filled evenly

Osmosis When water is diffused across the cell membrane It is important for a cell to maintain water balance as their environment changes

Solution Types Hypotonic – less molecules outside cell Isotonic – equal molecules on both sides of the membrane Hypertonic – more molecules outside cell

Lower concentration of solute Higher concentration of solute Equal concentration of solute H2O Solute molecule Selectively permeable membrane Water molecule Solute molecule with cluster of water molecules Net flow of water

Plant cell Animal cell Isotonic solution Hypotonic solution Hypertonic solution H2O H2O H2O H2O Animal cell H2O H2O H2O H2O Plant cell

Cytoplasm The area between the nucleus and plasma membrane Holds organelles Cytosol – fluid between the organelles

Ribosomes Protein synthesis read instructions to build proteins from DNA Found in all organisms!

Eukaryotic Cell Parts

Review Ribosomes Cytoplasm Cell Membrane

Nucleus Function: Directs activities of the cell Protects genetic information (DNA) Controls the cell's growth and reproduction. Parts: Nuclear Envelope Nucleolus Chromatin Nuclear Pores

Compartmentalize Organelle - differentiated structures within the cell Advantage: Allows the cell to accomplish more metabolic processes Incompatible activities can happen at the same time

Endoplasmic Reticulum “network within the cell” 2 parts Rough Endoplasmic Reticulum (RER) Embedded with ribosomes Synthesizes and modifies proteins

Endoplasmic Reticulum cont. Smooth Endoplasmic Reticulum (SER) Embedded with enzymes Synthesizes lipids Processes toxins and drugs in liver cells Stores and releases calcium ions in muscle cells

Vesicles Used for transportation within the cell Buds off of ER and Golgi Body

Golgi Apparatus Modifies, packages, and ships cell products that come from the ER or ribosomes

Lysosomes & Peroxisomes Contains digestive enzymes to break down nutrients, bacteria, and wastes Not present in most plant cells Peroxisomes Breakdown Hydroxide (H202) by-product

Rough ER Transport vesicle (containing inactive hydrolytic enzymes) 1 Golgi apparatus Plasma membrane Lysosome engulfing damaged organelle 5 Lysosomes 2 3 Engulfment of particle “Food” Food vacuole Digestion 4

Mitochondria Location for cellular respiration Converts the chemical energy of foods into ATP Double membrane layer

Cytoskeleton The cell’s internal skeleton helps organize its structure and activities A network of protein fibers Actin subunit Microfilament 7 nm Fibrous subunits 10 nm Intermediate filament Microtubule 25 nm Tubulin subunit

Centrioles Main function is to produce and organize the cytoskeleton during cell reproduction

Animal Cell Plant Cell

Cell Wall rigid boundary made largely of cellulose for support and environmental resistance Central vacuole Not in animal cells Chloroplast Cell wall

Central Vacuole Main function: Store water Contains enzymes – equivalent to animal lysosomes Holds pigments for flower color Chloroplast Central vacuole Nucleus Colorized TEM 8,700

Chloroplast Converts light energy into chemical energy Only in plants and some protists Chlorophyll = green pigment

Central vacuole Not in animal cells Chloroplast Cell wall

Nucleus Smooth endoplasmic reticulum Rough endoplasmic reticulum Ribosomes Golgi apparatus Plasma membrane Mitochondrion Flagellum Not in most plant cells Lysosome Centriole Microtubule Cytoskeleton Intermediate filament Microfilament Peroxisome