Transcript Chapter 2
Chapter 2 Section 2-3 Cells the Unit of Life • Cells – smallest units that carry on all the activities and functions of a living thing • Microscopes – instruments that enlarge tiny things - have one or more lenses to aid in enlarging small things Microscopes • Zacharias Janssen Dutch – Made reading glasses – Put two magnifying lenses together • Compound – two or more lenses Microscopes • Simple – one lens -magnifying glass • Anton van Leeuwenhoek • Dutch scientist • Simple micro used glass bead for a lens • Magnified up to 270X What did van Leeuwenhoek see? Animalcules – coined term of pond creatures found by van Leeuwenhoek. The Compound Light Microscope • Lets light pass through an object and then through two or more lenses Objective lens – eye piece power of 10X Body Tube – holds eyepiece Revolving Nosepiece – holds second objectives Arm – used to safely carry microscope Stage – place slide over hole to receive light Stage clips – holds slide in place Diaphragm – controls amount of light Coarse adjustment knob – use first to focus image NEVER use after image is focused Fine adjustment knob – use second for finer focus Light source – light Base – bottom of microscope • Stereo microscope – 3D view of image • - used to view thick objects or whole objects like an insect • - has two ocular eyepieces • Electron Microscope – for objects too small to be viewed through a compound light microscope • - uses magnetic field to bend beams of electrons • - can magnify one million times Electron microscope images • Robert Hooke – – Thin slice of cork – Looked like tiny empty boxes - cells – Drawing of cork cells – Dead – no organic material inside of them Schleiden and Schwann • German scientists who discovered all living things –plant and animal- are made of cells. • Rudolph Virchow – Theory that cells come from other living cells – They divide to form new cells The Cell Theory • All organisms are made of one or more cells. • Cells are the basic unit of structure and function of all organisms. • All cells come from other living cells. Section 2-4 Cell Organization • Prokaryotic cells – no membrane around the nuclear material – Ex. Bacteria • Eukaryotic cells – have a nucleus with a membrane around it – Ex. Plant and animal Cytoskeleton Framework of fibers which helps cell : maintain shape stretches and contracts with cell supports cell Cell membrane • Outer layer of cell • Flexible • Allows material to go into and out of cell • Semipermeable • Made of double layer lipids (fats) with protein in the middle. Nucleus • Directs the activity in the cell • Nuclear membrane – membrane that holds the nuclear material inside the nucleus • Chromatin – genetic material (DNA) • Nucleolus – makes ribosomes • RNA-protein recipe Cytoplasm • Jelly material inside cell • Held in by cell membrane • Constantly streaming • Allows other organelles to hang suspended in cyto Endoplasmic reticulum ER • Folded membrane • From nucleus to cell membrane • Moves material around the cell • Train tracks of cell Endoplasmic reticulum • Rough ER – contains ribosomes • Smooth ER – no ribosomes - makes lipids (stored energy) Ribosomes • Makes proteins • Found on ER – Rough ER • Receives messages from nucleus about how to make and kinds of proteins • Some found scattered in cyto Mitochondria • Powerhouse of cell • Food is broken down • Energy is released Golgi Apparatus • Stacks of flattened membranes • Package proteins • Moves proteins outside of the cell or to areas in cell that need them. Lysosomes • Containers of chemicals that digest wastes • Digest worn out cell parts • Breakdown food • Helps to breakdown dead cells Vacuoles • Storage containers of the cell • H2O • Food • waste • Plant cells – very large vacuoles – Helps to keep plant rigid Centrioles • Found in animal cells only • Hollow tubular structures arranged in a bundle • Used in animal cell reproduction Plant Cell • Cell wall – rigid structure outside of the cell membrane it gives plant; • support • protection • shape • chloroplasts – contains chlorophyll • Light sensitive • Helps light to produce sugar for plant Organelles of the Animal Cell Bacteria cell • • • • • • Prokaryotic Cell wall- capsule Cytoplasm Chromosome No nuclear membrane ribosomes