Bio Review.pdf

Microscopy Magnification - ability to enlarge an object Resolution - degree of detail visible in an image Compound Light Microscope - Uses multiple lenses to compound the level of magnification Electron Microscopes 1. Scanning Electron Microscope - Scans the surface of t...

Microscopy Magnification - ability to enlarge an object Resolution - degree of detail visible in an image Compound Light Microscope - Uses multiple lenses to compound the level of magnification Electron Microscopes 1. Scanning Electron Microscope - Scans the surface of the specimen - Uses a computer to create a 3D image 2. Transmission Electron Microscope - Scans through the specimen - Creates a 2D image of the ultrastructure Techniques: 1. Freeze Fracture - Rapidly freezing a specimen then fracturing it - Allows us to see the plane through the fracture - Allowed the understanding of the cell membrane (presence of integral proteins) 2. Cryogenic Electron Microscopy - Uses a low temperature to freeze a specimen - Bombards the specimen with electrons - Allows us to see the specimen with no ice crystals or artificial structures - Can show the 3D form of protein 3. Immunofluorescence - Using a fluorescent dye which is attracted to a specific target - Allows the target to be identified in a sample Cell Theory 1. All cells must come from preexisting cells. 2. Cells are the basic unit of life. 3. All organisms are made of one or more cells. Prokaryotic Cells - Lack membrane-bound organelles - Contain 70S ribosomes - DNA is in a region called the nucleoid. The DNA is in the form of a singular circular chromosome. - Cell wall is made of peptidoglycan Eukaryotic Cells - Compartmentalized with membrane-bound organelles - Contain 80S ribosomes - Rough ER has ribosomes attached Life Processes 1. Metabolism 2. Reproduction 3. Sensitivity 4. Homeostasis 5. Excretion 6. Nutrition 7. Growth Organelles - Must have specific & vital functions and discrete structure - Organelles common to all cells: DNA, cytoplasm, cell membrane, ribosomes - Structures not considered ribosomes: cell wall, cytoskeleton, cytoplasm No Membrane Single Membrane Double Membrane Ribosomes Smooth ER Nucleus Microfilaments Rough ER Mitochondria Golgi Apparatus Chloroplasts Lysosomes Chromoplasts Vesicles Amyloplasts Vacuoles 1. Nucleus - double membrane with pores - contains chromosomes (DNA associated with histone proteins) - densely stained chromosomes (usually towards the edges) are coiled - responsible for DNA replication, mRNA modification and transcription, ribosome synthesis 2. Rough ER - Consists of flattened membrane sacs called cisternae - Ribosomes are attached to cisternae  - Responsible for protein synthesis 3. Smooth ER - Consists of a branched network of tubular membranes - Responsible for the synthesis of lipids, phospholipids, and steroids 4. Free Ribosomes - Synthesizes protein, releases it into the cytoplasm as enzymes and more - Synthesized in the nucleus 5. Golgi Apparatus - Consists of cisternae that are shorter than rER, curved, have no ribosomes - Has many vesicles nearby - Responsible for protein processing, modification, and transportation 6. Mitochondria - Double membrane, spherical or ovoid - Inner membrane is invaginated to form cristae - Fluid inside is called the matrix - Where cellular respiration takes place (production of ATP) 7. Vacuole - Single membrane and contains fluid - Responsible for digestion and in prokaryotes, expelling excess fluid 8. Vesicle - Smaller vacuole - Responsible for the transport of material within the cell 9. Lysosomes - Vesicles of the golgi apparatus - Contains high concentration of proteins - Contains digestive enzymes - Responsible for breaking down waste material and organelles 10. Chloroplasts - Double membrane, spherical or ovoid - Contains stacks of thylakoids - Responsible for photosynthesis  - Produces glucose and other organic compounds 11. Microtubules - Small cylindrical fibers - Move chromosomes during cell division 12. Centrioles - Formed by 2 triple 3 microtubules - Serve as an anchor point for microtubules during cell division and those in cilia and flagella Atypical Cell Structures 1. Red Blood Cells - Enucleated in mammals - Gives the cell flexibility and allows for more hemoglobin to be carried 2. Phloem Sieve Tubes - Only cell membrane remains - Connected to a companion cell - Allows for the efficient flow of nutrients 3. Skeletal muscles - Syncytium (cells fuse together and form a multinucleate structure) - Enhances protein synthesis 4. Aseptate fungal hyphae - Coenocyte (multinucleate; caused by division of the nucleus without cellular division) - Efficient nutrient distribution Cell Compartmentalization - Compartmentalization is the separation of the cell interior that allows for the simultaneous occurrence of metabolic processes and reactions - Benefits of compartmentalization 1. Concentration of enzymes and substances 2. Organelles can move with their contents 3. Conditions such as pH can be maintained 4. More membrane surface area for membrane processes to occur 5. Separates incompatible functions - Benefits of nucleus cytoplasm separation 1. Protection of DNA 2. Allows for transcription and translation in separate locations Cell Membrane  - formed of a phospholipid bilayer in water - Selectively permeable 1. Phospholipid - Amphipathic molecule - Hydrophilic head made of a phosphate group and glycerol - Hydrophobic tail made of fatty acids 2. Cholesterol - Amphipathic - Responsible for membrane fluidity - Imbedded in the hydrophobic core of the membrane - 1 polar OH group is attracted to the hydrophilic head - Hydrocarbon chain is linked to the hydrophobic tails 3. Integral Protein - Imbedded in the membrane - Has many functions like ion channels and protein pumps 4. Peripheral Protein - Found on the surface of the membrane, attached to a lipid or a protein - Assists in cell communication, enzymes, structural support, and transport 5. Glycoprotein - A protein to which a carbohydrate chain is attached - Assist in cell adhesion and recognition 6. Glycolipid - A lipid to which a carbohydrate chain is attached - Assists in cell adhesion and recognition Simple Diffusion - Follows the concentration gradient - Occurs with non-ionic, lipid-soluble, small molecules Osmosis - Net movement of water molecules from a lower solute concentration to a higher solute concentration - Occurs with water molecules - Water molecule permeability varies, it is increased by aquaporin (an integral transmembrane protein) Facilitated Diffusion - Follows the concentration gradient - Uses channel proteins - A channel protein has a pore whose diameter and chemical composition allows only one type of particle to pass through - Occurs with ions (potassium, chloride, sodium ) and polar molecules (glucose) Active Transport - Goes against the concentration gradient - Uses a protein pump - A protein pump as 2 conformations and uses ATP to switch between the conformations Stem Cells - Have the ability to self-renew and to become any cell in the body 1. Embryonic stem cells - Pluripotent (can become any cell in the body) - Found in the blastocyst 2. Adult Stem Cells - Multipotent (can become a cell based on tissue/organ and its function) - Most important for body maintenance 3. Induced Pluripotent - Adult stem cells reprogrammed to become pluripotent 4. Totipotent stem cells - Forms the 3 primary germ cell layers and extraembryonic structures