Ch. 7 1. Introduction to Cells Cell theory Cell size Cell shape Cell features

C E L L T H E O R Y All living things are made up of one or more cells (living = cells) Cells are the basic unit of structure & function in organisms (smallest living part = cells) All cells rise from existing cells (cells come from cells)

C E L L S I Z E ** 200 types of cells** **100 trillion cells = human body** Cell size limited by surface area-to-volume ratio Surface area (cell membrane) = big = a lot of places for substances to go in & out So. . . A large surface area to volume ratio = Volume (total space cell can exchange takes up) = small = a little substances bit of space to have to travel more efficiently Ex: 6:1

C E L L S H A P E A cell’s shape reflects its function Shape may increase surface area for exchange Grow in some ways & remain small in other Nerve cells = much longer than they are thick Skin cells = broad & flat Makes surface area to volume larger

C E L L F E A T U R E S ALL CELLS HAVE… 1. Cell membrane ~ outer boundary 2. Cytoplasm ~ fluid inside cell (cytosol) & all structures suspended

C E L L F E A T U R E S ALL CELLS HAVE… 3. Ribosomes ~ proteins are made here! 4. DNA ~ instructions, regulates activities, enables reproduction

Features of Prokaryotic Cells (single celled) DNA = a single loop near center Ribosomes & enzymes = in cytoplasm Cell wall surrounds membrane Structure & support Capsule allows cling to surfaces Very small Live in wide range of habitats

Features of a Eukaryotic Cell Single celled or multi cellular Complex organization = more specialized functions Contains compartments separated by membranes = organelles (some are connected by channels) DNA in a nucleus

2. INSIDE the cell: Framework Cytoskeleton Helps cell move, keep its shape, & organize parts Microfilament ~ long, thin, actin, contract to pull in & expand to push out Microtubules ~ thick, hollow, tubulin, info. mol. pass thru Intermediate fibers ~ mod. thick, anchors organelles & enzymes

Cytoskeleton

INSIDE the cell: Directing activity Nucleus “The Brain” Double membrane (nuclear envelope) which protects & houses DNA Pores to allow passage of RNA & ribosome parts Contains nucleolus, which makes ribosome parts

INSIDE the cell: Directing activity Ribosomes Made of protein & RNA “Free” ~makes proteins that remain in cell “Bound” ~makes proteins that leave cell ~attached to organelle

INSIDE the cell: protein processing Endoplasmic reticulum (ER) System of internal membranes which move stuff Rough w/ ribosomes modify proteins for export Smooth w/o ribosomes makes lipids, breaks down toxic substances

INSIDE the cell: protein processing Golgi apparatus/body Set of flattened sacs Modifies proteins when they come in by vesicle from the ER Modifies, sorts, & packages proteins for export **VESICLES move these substances in & out of ER & golgi**

INSIDE the cell: energy production Mitochondrion “Power house” Makes ATP (cellular energy) in inner membrane Smooth outer membrane & folded inner membrane

INSIDE the cell: energy production Chloroplast Found in plant cells & some protist Uses light energy to make sugar from carbon dioxide & water ~ photosynthesis Double membrane w/sacs

INSIDE the cell: storage & maintenance Lysosome ~ contains enzymes that break down large molecules. Ex: food, old, damaged cell parts Central vacuole ~ large compartment of plant cells. Stores water, ions, nutrients & waste. If full, plants stand upright (turgur pressure). If lose water, plants wilt. Other vacuoles ~ food & contractile

3. Diversity in ________. Vary in . . . shape way obtain & use energy make up of cell walls Movement flagella  long, threadlike pili  short, thick, attachment

Diversity in ________. Animal cells Plant cells Central vacuole Chloroplasts Cell wall Vary in organelles Specialized function Ex: muscle cells=many mitochondria