biology

• Prokaryotic cells are ‘primitive’ = simpler structure than eukaryotic cells
• Prokaryotic: Filled with cytoplasm, making very few basic internal structures
• Eukaryotic cells are more than 100 to 10,000x larger than prokaryotic cells
• Eukaryotic cells have a nucleus (technically nuclear membrane) which contains DNA, organised into linear chromosomes whereas prokaryotic cells “DNA” (genetic information) is carried on circular pieces, freely moving throughout the cell
• cellular membrane: Protects organelles inside (barrier), transports toxic substances out of cell, transports nutrients into cell 

  Is selectively permeable; allowing some substances to go in and out
• A membrane enclosed organelle that contains chromosomes and keeps DNA safe from other cells (acts as a house) 

  Nucleolus: makes protein 

  
• Endoplasmic reticulum - a network of membrane bound sacs that are involved in the synthesis and transport of information/lipids/proteins

  General: makes proteins

  Rough: transports proteins

  Smooth: makes lipids

  Ribosomes make proteins

  
• vacuole - store substances within the cell (retains water)

  A plant cell contains a large, singular vacuole that is used for storage and maintaining the shape of the cell. In contrast, animal cells have many, smaller vacuoles.
• Lys = to break open/cut into

  lysosomes: small membrane bound organelles that contain enzymes that digest and recycle materials

  Lysosomes break apart molecules (food, metabolic chemicals

  Recognise in drawing = circles w dots inside

  Not in plant cells 
• mitochondria - site of aerobic respiration, where most of the energy is released

  Generates energy needed to power the cell for biochemical reactions 

  Holds its own DNA = can only be tracked through the ‘mother’ (female only; women egg has cell membrane, cytoplasm, and mitochondria 
• Chloroplasts = facilitates photosynthesis 

  Chloro = pigmented compound, captures sunlight, converts into storable glucose 

  When night-time plant cells take the stored glucose made in the day and ‘unlock’ mitochondria to make energy throughout the night
• cell wall

  • maintains shape of cell structure 
  • animal cells don't have cell wall (hence why we are ‘squishy’)
• golgi apparatus: Takes chemicals, changes before sending off to cell (repackaging proteins)

  secretory vesicle is part from golgi apparatus pulled apart (bubble form)
• All cells are held together as a unit by the cell membrane (also called the plasma membrane)
•  In plant cells, the cell membrane is surrounded by a cell wall composed of cellulose
• fluid mosaic model is the current model for cellular membrane structure
• cellular membrane heads are hydrophilic and tails are hydrophobic, hence the phospholipid bilayer structure
• Macromolecules: cells carries out function to grow , repair, and reproduce
• Carbohydrates 

  • source of energy
  • storage of energy
  • structural component

  tends to be a hexagon shape and is glucose in human bodt
• Lipids 

  • energy storage
  • structural part of membrane
  • hormone components

  phospholipid from phospholipid bilayer, cholesterol
• Nucleic acids

  • controls cell activity
  • protein information
  • RNA (manufacture of proteins)

  DNA: chemical information
• Proteins (big and important/critical many roles)

  • structural support role in cells and tissues
  • biochemical catalyst

  e.g insulin(hormones), enzymes, building blocks, initiators of cellular death
• Extrinsic protein: goes ½ through the cell membrane, other name is peripheral protein 

  Intrinsic proteins: goes completely through the cell membrane, other names is transmembrane/integral protein
• Glycoproteins: carbohydrate branch, acts as a receptor for signalling hormones (can attach to both proteins) 
• Cholesterol molecules; the cell membrane is dynamic, proteins move within the phospholipid bilayer, getting the name of a fluid mosaic model, cholesterol gives structure to the otherwise fluid membrane 
• 3 types of microscope analysis:

  • x-ray crystallography
  • differential centrifugation
  • fluorescence microscope
• Fluorescence microscope: uses a high intensity light source that excites a fluorescent species, giving the specimen a ‘glow’ that allows us to see basic structures used to examine cells that are naturally or artificially fluorescent.
• differential configuration microscope: Separates substances based on density
• x-ray diffraction patterns to generate high resolution, 3D structures of small molecules (e.g proteins, small organic molecules, and materials). 
• Transmission electron microscope (TEM)

  Electrons pass through the sample so the image is flat and 2D, following factors must be followed to let us see details of structures within:

  • sample has to be dried
  • fixed in special resin
  • sliced extremely thin
• Scanning electron microscope (SEM)

  Electron beam doesn't pass through, but scatters from contact with sample computer analysis scattering to generate a 3D and detailed surfaced image, following factors must be followed to let us see details of the surface layer:

  • specimen coated with layer of heavy metal 1 or 2 atoms thick (often gold)
  • temperature can rise to 150°C where the beam hits the sample
• Bright field microscope

  (average light microscope found in classrooms) uses light to illuminate a sample and create an image. The sample is placed on a glass slide and illuminated by a light source, following factors must be followed to let us see structures

  • thin slices of said sample
  • usually samples are dyed(stain solution) so structures are more clearer to see
• Q. Why is it better to use stains on plant and animal cells when using a light microscope? 

  Without staining, the direct passage of light does not provide sufficient contrast to distinguish many parts of the cell
• Diffusion - passive

  The plasma membrane separates the contents of the cell from its surroundings providing a barrier to its external environment. It not only regulates what comes inside the cell but also how much of a given substance enters a cell. 
• Passive = doesn't require push, acts on itself

  Active = requires energy, to make transfer possible 

  Diffusion = happens on its own
• Osmosis - passive

  movement of water against permeable membrane (exactly like diffusion but water specifically) 
• Active Transport occurs when materials required by the cell are higher in concentration inside the cell compared to solutions surrounding the cell 

  • Requires energy (metabolic energy released from breakdown of ATP, a form of energy produced during cellular respiration)
  • Specific proteins in plasma membrane act as transporter/carriers to move substances through 
  • Move materials across the cell membrane  
• synaptic transmission is the process of the transmission of information from one neuron to another
• risk: Iodine is flammable, causes eye irritation, dizziness, drowsiness

  management: Keep away from flame/sources of ignition, wear safety goggles whilst handling and keeping iodine out, increase ventilation (fans, windows, and doors open) 
• Autotrophic organisms are those which can make their own food(auto=self ; trophic = feeling). Plant cells with chloroplasts are autotrophic

  e.g autotrophs -> photosynthesis as they automatically absorb energy to drive chemical reactions