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Foundations in biology

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Use of microscopyMicroscopes can be used to anaylse cell components and observe organelles<br><b>Optical(light microscopes)</b><br>   -Use light to form an image<br>   -Limited resolution and magnifiation (max resolution of around 0.2 micrometers)<br><b>Electron microscopes</b><br>   -Use electrons to form an image<br>   -Higher resolution and magnification so more detailed image<br><b>Transmission electron microscope (TEM)</b><br>   -Use electromagnets to focus a beam of electrons <br>   -Give high resolution which allows internal structures to be seen <br>   -Can only be used with very thin specimenrs or thin sections and cannot      be used to observe live specimens since theres a vacuum inside TEM<br><b>Scanning electron microscope (SEM)<br>   </b>-Scan a beam of electrons across the specimen which bounces off the surface of the specimen to form an image<br>   -Can produce 3D images and so external, 3D structures can be observed<br>   -Give lower resolution and cannot observe live specimens<br>   -Do not produce colour image
Organelles in animal cell Nucleus ( Nuclear envelope, chromatin, nucleolus)<br>Plasma membrane<br>Endoplasmic reticulum (SER and RER)<br>Ribosomes<br>Golgi apparatus<br>Peroxisome<br>Microtubule<br>Microfilament<br>Microvilli <br>Centrosome<br>Centrioles<br>Mitochondrion<br>Lysosome<br>Cytosol
NucleusContains the cell's DNA  (linear chromosomes)<br>Controls the actions of the cell and the DNA in the nucleaus contains instructions for the synthesis of proteins <br>Ribosomal RNA is joined together with associated proteins in the nucleus to assemble the ribosomal subunits
Nuclear envelopeDouble membrane that surrounds the nucleus<br>Contrains pores which controls the passafe of ions, molecules and RNA between the nucleoplasm and cytoplasm
NucleolusSite at which ribosomes are made<br>Also immobolises proteins and forms signal recognitionparticles
Plasma membraneProtect the cell from its surroundings<br>Anchors the cytoskeleton to provide shape to the cell and attaching to the extracellular matrix and other cells to help group cells to form tissues<br>Plays a role in seceral cellular processes (e.g cell signalling)<br>Fluid mosaic model describes the structure of the plasma membranes <br>
Rough endoplasmic reticulumFolds and processes proteins made on the ribosomes<br>Series of flatterend sacs, enclosed by a ribosome filled membrane (folded membrane called cisternae)
Smooth endoplasmic reticulum "Synthesise and stores lipids and carbohydrates<br>Packages the lipids for them to be transported to the Golgi apparatus<br>I<b><span style=""font-weight: 400;"">nvolved in the detoxification of toxins that are contained in the cell such as alcohol and by products of metabolism such as CO2 and urine</span></b>"
Golgi apparatus"<div style="""">Packages macromolecules into vesicles for transportation around the cell</div><div style="""">Membrane bound structure with a stack of curved and folded membranes called cisternae</div><div style=""""> The Golgi apparatus has two faces </div><div style="""">   -The cis face receives proteins and lipids, it is therefore facing the ER</div><div style="""">   -The trans face releases proteins and lipids</div><div style="""">The cisternae and inner lumen package the proteins and lipids</div><div style="""">The Golgi apparatus also makes lysosomes</div>"
MitochondriaSite of aerobic resp<br>   -Make ATP via aerobic resp <br>Surrouneded by double mekbrane with the inner membrane foldred to form cristae <br>The matrix formed by the cristae contrains enzymes needed for aerobic resp, producing ATP
RibosomesSite of protein synthesis<br>Small organelles made of protein subunits so arent covered by a membrane<br>Can be free floating or attached to the cytoplasmic side of the ER
LysosomesSpecialist forms of vesicles which contrain hydrolytic enzymes (enzymes that break biological molecules down)<br>Break down waste materials; such as worn out organelles<br>Used extensively by cells of the immune system
Peroxisome"<span style=""background-color: rgb(255, 255, 255); color: rgb(0, 0, 0);"">Responsible for the protection of the cell against metabolic hydrogen peroxide<br></span>Involved in lipid biosynthesis "
CytosolThe fluid around the cellular organelles in which different chemical reactions take place
Cytoskeleton"It i<span style=""color: rgb(0, 0, 0);"">s <span style=""background-color: rgb(255, 255, 255);"">a network of protein fibres that perform a number of different functions within the cell<br></span></span>Functions:<br>-Maintaining the shape of the cell.<br>-Securing some organelles in specific positions.<br>-Allowing cytoplasm and vesicles to move within the cell.<br>-Enabling cells within multicellular organisms to move.<div><div><div><div>Made up of three types of fibres; microfilaments, intermediate filaments, microtubules</div></div><div><div></div></div><div><div></div></div></div><div><div><div><div></div></div><div><div></div></div></div></div></div><div><div><div></div><br></div></div>"
MicrofilamentsNarrowest protein <br>Made of two intertwined strands of a gobular protein called actin <br>Actin works together with a motor protein called mysoin <br><b>Important for cellular events requiring motion (like cell division)<br>Provide rigidty and shape to the cell </b><br>  -they can disassemble and reform quicklly, allowing the cell to change its shape and move (used by WBC)
Intermediate filaments Made of several stands of fiborous proteins that are wound together<br>Bear tension, maintaining the shape of the cell and anchor the nucleus and other organelles in place
MicrotubulesHelp the cell resist compression<br>Provide a track along which vesicles move through the cell<br>Pull replicated chromosomes to opposite ends of a dividing cell<br>Pull replicated chromosomes to opposite ends of the dividing cell 
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Explain the bonding of water-Composed of 2 hydrogen atom and one oxygen atom, covalently bonded with hydrogen bonds<br>-Although water is electronically neutral the sharing of electrons is uneven<br>     -Oxygen attracts electrons more stronly than hydrogen resulting in a slightly negatively charged region whereas hydrogen has a slightly postively charged region<br>-As a result water is a polar moleule due to the uneven distribution of electrons
Water as a solventSince water is a polar molecule and therefore acts as a universal solvent, it has the ability to dissolve many ionic and polar covalent compoints<br>As a result it is a good medium for transportation and metabolic reactions<br>Both eukaryotic and prokaryotic cells contain a large amount of dissolved substances <br>  -Bodies of waters sich as ponds and waters contrain dissolved oxygen used in respiration for the organisms that live there<br>  -Blood plasma contains a large amount of dissolved substances and so water is used as a good transport medium<br>   -Water also used to transport substances in the xylem<br>
Water has a high specific heat capacityDue to the many hydrogen bonds in water a lot of energy is required to break them thus, the temperature of water doesnt flucuate much <br>  -Despite hydrogen bonds being relatively weak individually, the intermolecular bonds are strong <br>As a result, water is a suitable habitat and good for enzymes
High latent heat of vaporisationLarge amount of energy is needed to break hydrogen bonds and for water to evaporate which allows organisms to cool themselves without losing a great deal of water <br>  -During sweating, heat energy is used to evaporate water from the surface of the skin, this transfer of heat energy allows the organism to cool down
Cohesion of water-Water molecules tend to stick together due to the hydrogen bonds<br>-This allows water to act as a transport medium <br>-Cohesion also causes surface tension when water meets air<br>   -Surface tension is useful as it allows water be used as a habitat for some organisms (e.g<br>-The adhesion of water to other molecules is also effective and is thanks to water being a polar molecule<br>-The effects of adhesion and cohesion result in water exhibiting capillary action which is the process in which water can rise up a narrow tube against gravity (e.g water up the xylem)
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