Bio Study Notes - Cells as the Basis of Life PDF

Bio study notes Module 1: Cells as the basis of life Inquiry Question: what distinguishes one cell from another? What are cells: Cells are the basic unit of life and reproduction Cell theory ❖ All living things are composed of cells or are the product of cells (viruses, etc) ❖ All c...

Bio study notes Module 1: Cells as the basis of life Inquiry Question: what distinguishes one cell from another? What are cells: Cells are the basic unit of life and reproduction Cell theory ❖ All living things are composed of cells or are the product of cells (viruses, etc) ❖ All cells are produced from pre existing cells Evidence of cells - Technology, specifically microscopes Size of cells ❖ Plant: 20-100 micrometers (μm) ❖ Animal: 5-20 μm ❖ Bacteria: 0.1-5.0 μm Prokaryotic Cells About Name meaning: ‘pro’ before ‘karyon’ nucleus, thus ‘before nucleus’ ❖ Lack of nucleus and membrane bound organelles ❖ DNA found within cytoplasm  ❖ Generally much smaller cells ❖ More ancient and primitive ❖ Can exist only as unicellular organisms ❖ Includes bacteria and archae Cell Shape Name Shape Image example Bacillus Rod shaped Lactobacillus bacteria Coccus Spherical or Streptococcus generally round bacteria Spirilum Curved, can be gently curved or corkscrew shaped Spirochatae spiral Vibrio Straight rods that sometimes have a sinlge rigid curve Cell wall chemical composition: Antibiotics: ❖ Stiff cell walls composed of ❖ Target cell wall substances such as proteins, acids ❖ Diminish the process of cell wall ❖ Bacteria: most contain formation, breaking the linking of peptidoglycan, a protein made of molecules and therefore destroying sugars and polypeptides the cell ❖ Archaea: psuedopeptidoglycan, similar makeup to peptidoglycan Eukaryotic cells About Name meaning: ‘eu’ true, ‘karyon’ nucleus, ❖ Distinct cell nucleus which contains thus ‘true nucleus’ genetic material (chromosomes) ❖ Contain structures built from or surrounded by membrane, called organelles  ❖ Eukaryotic cells evolved from prokaryotic cells. Endosymbiotic theory: Large host cells and ingested bacteria become dependant on each other which results in a permanent relationship. This theory got its name because symbiosis occurs when two different species benefit from living and working together. ❖ Mitochondria and chloroplasts have their own DNA. This is proof of the theory Cell Organelles ❖ Cell structure and storage ❖ Enegry transformation Organelle Function Found in Image plant/animal/both Chloroplasts: Convert light energy Plant ❖ Disk shaped to chemical energy ❖ Double membrane (photosynthesis) ❖ Own DNA ❖ Contain chlorophyll (green pigment Mitochondria: Perform chemical Both ❖ Double membrane respiration: combine ❖ Own DNA oxygen and glucose ❖ # in cell depends on to create ATP so cell how much energy the can use energy type of cell requires Cell Wall: Provides structural Plant, fungi ❖ Surrounds membrane support and ❖ Made up of a network protection of cellulose and microfibrils Cell membrane: Controls movement both of substances into and out of cell’s internal environment Barrier against external environment Cytoplasm: Suspend organelles both and ‘fill up’ cell ❖ Fluid, jelly-like substance made up of mostly water Cytoskeleton: Hold organelles in both ❖ Made up of place microtubules, microfilaments, intermediate filaments ❖ “Protein spiderweb” Centrioles: Involved in cell both ❖ Small cylindrical division, pull structures made of chromosomes apart microtubules in pair Vacuole: Store substances for Plant: large and ❖ Membrane bound when cell needs permanent, give cell vesicle that contains shape (turgal fluid pressure) ❖ Size + quantity varies Animal: small, for a short period of time ❖ Make and process cell substances Organelle Function Found in image animal/plant/both Nucleus Contains the cell’s Both ❖ Surrounded by genetic information in nuclear membrane the form of chromosomes which have DNA Is needed for growth, repair and proper functioning Nucleous Produces and Both ❖ Found in the nucleus assembles the cell’s ❖ Made of proteins ribosomes Ribosomes Uses information Both ❖ Made of RNA from genes to ❖ Aren’t “technically” produce proteins organelles ❖ Found floating in cytoplasm or connected to endoplasmic reticulum Endoplasmic Reticulum Creates tunnels Both (ER) through which ❖ Connected to the substances can move nucleus in some parts through ❖ Network of flattened, interconnected Smooth ER: membranes Makes lipids Rough ER (has ribosomes attached): Process and modify  proteins Golgi Body/apparatus Processes and both ❖ Flat membrane sacs packages substances stacked on top of made by cell each other ( like pancakes) After processing, pinches off to form bubble around substance, these become known as vesicles Lysosomes Membrane sacs Animal ❖ Example of vesicle containing digestive made by golgi body enzymes, they break down other substances such as cellular waste, foreign particles Pilli and flagella Hair like appendages Fungi, prokaryotic used to help the cell cells move around Technologies The Light Microscope  ❖ Key to the development of understanding cells Basics ❖ Uses visible light and 2 lenses to make specimen/sample bigger ❖ Light shines through specimen ❖ Light travels through objective and ocular lens ❖ Light is refracted to create magnified image Prep and set up ❖ Specimen will either be: whole organism, smear of cells, thin slice 1. Put on glass microscope slide 2. Add dye to stain certain structures 3. Add fluid and coverslip Set up 1. Pick up and place on bench, 5cm from edge 2. Plug in and turn light on 3. Put on lowest objective lens (4x) 4. Place prepared slide on stage 5. Use diaphragm to adjust amount of light passing through specimen (brightness) 6. Lower objective lens (close but not touching) 7. Focus using coarse and fine focus to get clear image (can switch to higher objective) The Electron Microscope Basics ❖ Uses beam of electrons and electromagents to make specimen look bigger ❖ Electrons: small and sensitive, bounce off anything ❖ Direct beam of electrons can only be achieved in vacuum conditions ❖ Electron gun shoots beam of electrons towards specimen ❖ Focused and controlled by electromagnets ❖ When electrons hit/interact with specimen, beam gets scattered  ❖ The way the beam scatters depends on structure of specimen ❖ This scattering can be detected and turned into an image by a computer, this image is called an ‘electron micrograph’ Transmission electron microscope (TEM) Prep ❖ Treat specimen with chemicals which increase structural strength ❖ Remove all water using alcohol ❖ Embed specimen in resin ❖ Cut into thin slices Scanning Electron Microscope (SEM) Prep ❖ Treat specimen with chemicals which increase structural strength ❖ Remove all water using alcohol ❖ Coat specimen in thin layer of gold Differences TEM: broad beam shot at specimen- final image shows inside of cell SEM: super fine beam is systematically scanned across image - final image only shows outside of cell Confocal Micoscope ❖ Most advanced ❖ Highly focused laser through specimen ❖ High quality image of tiny part of specimen ❖ Move to get another image ❖ Sent to computer that enhances and stitches together to get 3D image Comapring Microscopes Can use: ❖ Tables ❖ Ven diagrams Example table: Feature Light microscope Electron microscope Purpose Magnified image of Magnified image of specimen specimen Radiation type light electrons Process of making magnification