Unit 3: The Cell & Its Environment Ch 5: Inside The Cell

Structure of Cells 3-D, not 2-D –spheres, cubes, or bricks –Many can change shape –Some have spikes, bulges, or other strange extensions

Sizes of Cells Vary in size –Some < ½ µm (1 µm = 1/1000 mm or 1/1,000,000 m) –bacteria among the smallest –egg cells among the largest

Why is there a limit to cell growth?

2 Main Types of Organisms Unicellular Organisms –Single cell Carry out all processes in one cell –Ex. amoeba, paramecium, euglena Multicellular Organisms –Many cells Division of labor –cells are specialized (specific functions) –Ex. You, dog, tree, elephant Why can multicellular organisms be big if there is a limit to cell size?

Organization Within Cells Why might cells need to be organized? How are they organized??? ____________

Surrounds each cell –creates boundary between cell contents & outside environment (including other cells) Acts as a gatekeeper –selectively permeable Cell (Plasma) Membrane

Cytoplasm Gel-like substance filling much of cell –approx. 70% water –Contains organelles –Some chemical reactions

Two Major Types of Cells Prokaryotes –No nucleus DNA  single chromosome –no mitosis –no membrane- bound organelles Eukaryotes (You – karyote!) –Nucleus DNA  multiple chromosomes –mitosis –Membrane-bound organelles

Two Major Types of Cells

Eukaryotic Cell Organelles Plant & Animal Cells –*Cell (plasma) membrane –*Cytoplasm –Nucleus –Nuclear membrane (envelope) –Nucleolus –*Ribosome –Endoplasmic Reticulum –Golgi Bodies (Apparatus) –Mitochondrion –Cytoskeleton –Vacuole –Lysosome Plant Cells –Chloroplast –*Cell wall Animal Cells –*Cilia & flagella –Centrioles

Nucleus Control Center for Cell –Surrounded by nuclear membrane (envelope) selectively permeable –Inside nucleus Chromatin –DNA & Protein »Genetic information –Before cell divides chromatin condenses into chromosomes Nucleolus

In nucleus –where RNA is produced –can have more than one

Ribosomes & Endoplasmic Reticulum Ribosomes –Synthesize proteins from amino acids –Thousands in cell attached to endoplasmic reticulum free in cytoplasm

Endoplasmic Reticulum (ER) –Network of interconnected, flattened, tube-like membranes –transport proteins through cell Rough ER (RER) –covered w/ ribosomes Smooth ER (SER) –Lacks ribosomes Ribosomes & Endoplasmic Reticulum

Golgi Bodies (Apparatus) Stacks of flattened, slightly-curved, sac-shaped membranes –Packages, modifies & exports proteins within & out of cell –Lie close to ER

Mitochondria Rod-shaped –Inner membrane is highly folded Why? Powerhouse of the cell –Creates energy (ATP) for cell from food (glucose) Cellular respiration

Cytoskeleton Made of microtubules & microfilaments –proteins Give cell shape & support Helps organelles move around cell

Vacuole Fluid-filled sac –Plant cells-large vacuole –Animal cells-small vacuoles Store food, water, waste Role in maintaining osmotic balance –Central vacuole Maintains turgor pressure in plants –Contractile vacuole Pumps water out of many unicellular freshwater protists –Why would these organisms need to pump out water?

Lysosomes Small, round vesicles formed from golgi bodies –mostly in animals cells contain digestive enzymes –break down larger food molecules –break down old, worn out cell parts Lysosome animation

Chloroplasts Green, oval-shaped plastids w/ double-membrane –Contains chlorophyll (green pigment) Site of photosynthesis –Makes food (glucose) & releases oxygen Plants & some protists Chloroplast Cyclosis

Cell Wall outside cell (plasma) membrane protection & support –made of cellulose or chitin plants, algae, fungi, bacteria

Cilia & Flagella made from microtubules –cilia Shorter & more numerous –flagella Longer, but few in number For motility (movement) –whip-like motion

Centrioles Paired, rod-like structures near nucleus –made of a cylindrical of microtubule pairs Animal cells play role in cell division –separate chromosome pairs during mitosis

Extras ID eukaryotic animal cell organelles: online.com/Objects/ViewObject.aspx?ID=AP online.com/Objects/ViewObject.aspx?ID=AP Cell Part ID interactive: online.com/objects/ViewObject.aspx?ID=AP114 03http:// online.com/objects/ViewObject.aspx?ID=AP Cell Organelles Game: