Cell Organelles 3.2
Objectives To determine the differences between plant and animal cells To discover the structure and function of cellular organelles.
Basic Cellular Structures Cell membrane (cytoplasmic membrane) All cells thin flexible layer around cell regulates what enters and leaves the cell Phospholipid bilayer Cell wall PLANTS ONLY strong layer on outside of cell membrane provides support and protection for cell
Basic Cellular Structures Cytoplasm The goop all the organelles float around in
Eukaryotes Have a Cytoskeleton cytoskeleton- network of proteins that changes to meet needs of cells. Made of protein subunits forming threads crisscrossing cell 3 types Microtubules: long hallow tubes- give shape, act as tracks for movement of organelles. Form fibers to pull half DNA to new cell during division. Intermediate filaments- give cell strength Microfilaments: smallest- enable cell to move & divide; play important role in muscle cells- relax, contract
Basic Cellular Structures Nucleus Contains DNA Only in Eukaryotes 1- DNA must be protected 2- DNA must be available for use @ proper times double membrane- nuclear envelope w/ large holes (pores) to allow molecules to pass to cytoplasm. nucleolus- dense region where ribosomes are made
Basic Cell Structures Endoplasmic Reticulum (ER) interconnected network of folded membrane Protein and lipid production Rough ER- studded with ribosomes Smooth ER- (no ribosomes) make lipids, break down alcohol & drugs Proteins made on ER- incorporated into cell membrane or secreted Ribosomes Synthesized in nucleolus then transported through pores to cytoplasm where proteins synthesized. where proteins are made proteins made from suspended ribosomes used in chemical reactions w/in cytoplasm Lysosomes filled with enzymes Defend cells f/ bacteria & viruses Break down damaged/worn out cell parts Lysosomal enzymes can destroy cell so enclosed in membrane Animals only
Basic Cellular Structures Vacuoles stores materials such as water, salt, proteins, and carbohydrates Animal cells have small but plants have large central vacuole Filled with fluid, strengthens cell, support plant Ex. Leaves of plant shrivel Golgi Apparatus Closely layered stacks of membrane Sort & deliver proteins Packages proteins, some store here or exported to other organelles
Basic Cell Structures Mitochondria All cells breaks down food to release energy for the cell Inner membrane has lots of folds where chemical rxns take place converting food into usable energy Have own ribosomes & DNA Suggest mitochondria were originally free prokaryote taken by larger cells
Basic Cell Structures Vesicles: small membrane-bound sacs that divide materials from rest of cytoplasm & transport materials in cell Short lived, formed & recycled as needed After protein made, ER pinches off vesicle to surround protein to transport safely to Golgi Apparatus.
Basic Cell Structures Centrosome & centrioles Small region of cytoplasm that produces microtubes In animal cells contains 2 centrioles perpendicular to each other (Animals) During cell division, double to make new centrosomes and move to opposite end of cells Microtubes grow from centrosome forming fibers that attach to DNA and help it divide into two cells Organize microtubes to form cilia and flagella- motion forces liquids past cell.
Plant ONLY Cells Structures Chloroplasts stores energy from sunlight Photosynthesis Outer and inner membrane (disk shaped sacs in inner membrane- thylakoids- contain chlorophyll Absorbs light Gives plan green color Key role in photosynthesis Also have own ribosomes & DNA (like mitochondria)
Plant ONLY Cells Structures Cell Wall: Strong, ridged layer Protection, support, shape Ex. Dead cells of tree bark still have cell walls- give support Cell wall composition varies for needs of organism ex. Plants and algae made of cellulose & polysaccharide b/c molecules can not easily diffuse across cellulose Channels allow water and other small molecule to pass through
Cell Structure p.74 Animal vs. Plant