Bio topic 2

• Within the eukaryotic cells the key organelles that you need to know the structure and function of


  • Nucleus
  • Endoplasmic reticulum
  • Golgi apparatus
  • Lysosomes
  • Mitochondria
  • Ribosomes
  • Vacuole
  • Chloroplasts
  • Cell walls
  • Plasma membrane
• Nucleus


  Where DNA replication occurs and it's a cytotranscription which is where mRNA is made and it contains the DNA which is a genetic code for the cell
• Nucleolus


  Site of RNA production and where ribosomes are made
• Rough endoplasmic reticulum (RER)


  Where protein synthesis occurs because of the ribosomes on the outside
• Smooth endoplasmic reticulum (SER)


  Where synthesis of lipids and carbohydrates occurs and they also get stored there
• Golgi apparatus


  A folded membrane making this systemy shape and we have vesicles that will pinch off from those cysteine once whatever it is that's going to be modified has been modified and packaged
• Things that can happen in the Golgi apparatus


  • Carbohydrates are being added to proteins to make glycoproteins which might be embedded within the cell membrane
  • Produce secretory enzymes
  • Carbohydrate transport
  • Modify lipids
• Lysosomes


  Bags of digestive enzymes and this is often involved in phagocytosis
• Mitochondria


  Site of aerobic respiration so you'll have lots of ATP production here, it's a double membrane organelle with the outer membrane and the inner membrane is this folded part making up the cristae and the inner membrane is where oxidative phosphorylation happens which is one of the key stages in aerobic respiration
• Mitochondrial DNA


  They have their own loop of DNA which is very similar to prokaryotic DNA and this is so that they can code for the enzymes that they need in respiration
• Ribosomes


  Found in prokaryotic and eukaryotic cells, they are not membrane bound and are made up of rRNA and proteins, the 80S is the largest size ribosome in eukaryotic cells and the 70S is a smaller sized ribosome found in prokaryotic cells as well as in mitochondria and chloroplasts, they are the site of protein synthesis
• Vacuole


  Only found in plant cells, it is filled with fluid and surrounded by a single membrane called a tonoplast and this is what helps to make the cell turgid and provide support, it has temporary stores of sugars and amino acids within the fluid as well and the pigments within it may color the petals and that's what helps to attract pollinators
• Chloroplasts


  Only found in plants, it is the site of photosynthesis, it is a double membrane organelle with the outer membrane, inner membrane and then on the inside we have even more membranes and that is these thylakoid membranes which stack up to create what we call a grana, the thylakoid membranes are embedded with proteins and pigments such as chlorophyll and therefore it's the site of the light dependent reactions in photosynthesis, the stroma which is the fluid parts surrounding the thylakoid membranes you have lots of enzymes in this location which are needed for the light independent stages of photosynthesis
• Cell walls


  Not in animal cells but they are in fungi and plant cells and they help to provide structural strength to the cells and prevent them bursting if lots of water moves in by osmosis, in plants they contain cellulose and in fungi they contain chitin
• Plasma membrane


  Found in all cells, it is the cell membrane or the cell surface membrane, it is made up of a phospholipid bilayer with different molecules embedded within it, it controls what can enter and exit the cell
• Key differences between prokaryotic and eukaryotic cells


  • Prokaryotic cells are much smaller
  • Prokaryotic cells don't have membrane-bound organelles
  • Prokaryotic cells have 70S ribosomes
  • Prokaryotic cells don't have a nucleus, their DNA is a single loop free in the cytoplasm
  • Prokaryotic cells have a cell wall
  • Prokaryotic cells may have plasmids
  • Prokaryotic cells may have a capsule
  • Prokaryotic cells may have flagella
• Viruses


  Acellular and non-living, the structure of virus particles consists of genetic material, capsid and attachment proteins, they replicate inside of host cells
• Methods of studying cells


  • Microscopes
  • Cell fractionation and ultracentrifugation
• Magnification


  How many times larger the image is compared to the object
• Resolution


  The minimum distance between two objects in which they can still be viewed as separate
• Types of microscopes


  • Optical microscopes (light microscopes)
  • Transmission electron microscopes
  • Scanning electron microscopes
• Optical microscopes


  Use a beam of light condensed by lenses to create the image
• Electron microscopes


  Use a beam of electrons condensed by electromagnets to create the image
• Optical microscopes


  Have lower resolution due to the longer wavelength of light
• Electron microscopes


  Have higher resolution due to the shorter wavelength of electrons
• Transmission electron microscope


  Extremely thin specimens, the electron beam passes through the specimen and some parts absorb more electrons so appear darker
• Scanning electron microscope


  The electron beam is scattered off the surface of the specimen to create 3D images
• Calculating magnification


  Image size = Actual size x Magnification
• Eyepiece graticule


  A scale on a glass disc within the optical microscope that can be used to measure the size of objects being viewed
• Cell fractionation


  1. Cells are broken open in a cold, isotonic, buffered solution

  2. Homogenization to break open cells

  3. Ultracentrifugation to isolate different organelles based on their densities
• Eukaryotic cells divide by mitosis or meiosis, prokaryotic cells replicate by binary fission, viruses do not undergo cell division but they do replicate inside host cells
• Stages of the eukaryotic cell cycle


  • Interphase (G1, S, G2)
  • Mitosis (Prophase, Metaphase, Anaphase, Telophase)
  • Cytokinesis
• Mitosis


  • Only one round of division
  • Genetically identical cells are created
• Host cell


  The cell that uses the genetic material to replicate the virus particle
• Eukaryotic cell cycle


  1. Interphase

  2. Mitosis
• Interphase


  The longest stage of the cell cycle, includes G1, S, and G2
• G1

  Cell increases in size, organelles double
• S phase


  DNA replication happens
• G2


  Further growth, preparation for mitosis, error check stage
• Nuclear division


  Mitosis or meiosis