BIOLOGY

• all right ninja nerds in this video today we are going to be talking about the structure and function of the cell
• if you guys haven't already go watch our video where we talk about how i study and prepare for videos within that i kind of gave you guys a sneak peek of how i pretty much went through studied this topic developed notes diagrams and then drew it all on the board
• now we're going to go through it before we get into this video though please continue to support us by hitting that like button commenting down in the comment section and please subscribe
• Nucleus


  The brain of the cell, the center of the cell where everything that a cell is kind of really begins in all centers around
• Nuclear envelope


  • Outer layer
  • Inner layer
• Outer layer of nuclear envelope

  Where ribosomes are found
• Inner layer of nuclear envelope

  Contains a protein structure called lamins that binds to DNA and histone proteins and controls cell division
• Nuclear pores


  Dispersed throughout the nuclear envelope, allow for transport of ions, proteins, nucleotides in and out of the nucleus
• Nucleolus


  Site of rRNA synthesis, important for making ribosomes
• Chromatin


  Made up of DNA and histone proteins, can exist in euchromatin (loose, for expression) or heterochromatin (tight, towards nuclear envelope)
• Functions of the nucleus


  1. DNA replication

  2. Transcription to make different types of RNA (mRNA, tRNA, rRNA)
• Rough endoplasmic reticulum (rough ER)


  Filamentous membranous structure with ribosomes on the surface, site of protein synthesis and protein folding, performs glycosylation
• Smooth endoplasmic reticulum (smooth ER)


  Lacks ribosomes, site of lipid synthesis including fatty acids, phospholipids, and cholesterol
• Rough ER


  Packages synthesized, folded, and glycosylated proteins into vesicles to transport to Golgi apparatus
• Smooth ER contains enzymes that synthesize lipids like fatty acids, phospholipids, and cholesterol which can be used to make hormones
• Lipid synthesis


  Primary function of enzymes associated with this process
• Lipids synthesized


  • Fatty acids
  • Phospholipids
  • Cholesterol
• Cholesterol


  Can become steroid hormones like testosterone, progesterone, estrogen
• Lipid synthesis process


  1. Precursor molecules taken up into smooth ER

  2. Enzymes in smooth ER use precursors to synthesize lipids

  3. Lipids packaged into vesicles

  4. Vesicles sent to Golgi or cell membrane
• CYP450 enzymes


  Important for detoxification, located in smooth ER
• Glucose 6-phosphate metabolism


  1. Glucose 6-phosphate transported into smooth ER

  2. Enzyme in smooth ER removes phosphate to produce glucose
• Smooth ER


  Stores calcium, pumps calcium out into cytosol as needed
• Golgi apparatus


  Packaging organelle that receives vesicles from ER
• Golgi apparatus


  • Receives vesicles from rough ER and smooth ER
  • Modifies proteins and lipids through glycosylation and phosphorylation
  • Packages modified molecules into vesicles
  • Sends vesicles to lysosomes, cell membrane, or for secretion
• Cell membrane


  Selectively permeable barrier that allows different types of transport
• Components of cell membrane


  • Phospholipid bilayer
  • Cholesterol
  • Integral proteins
  • Peripheral proteins
• Phospholipid bilayer


  Hydrophilic head groups, hydrophobic fatty acid tails
• Cholesterol


  Controls fluidity of cell membrane
• Lysosomes


  Contain hydrolytic enzymes that break down proteins, lipids, nucleic acids
• Hydrolytic enzymes in lysosomes


  • Proteases (break down proteins)
  • Lipases (break down lipids)
  • Nucleases (break down nucleic acids)
• Vesicular transport


  Moving things from outside the cell to inside the cell
• Cell membrane


  • Acts as a barrier for particular types of transport processes
• Lysosomes


  Spherical organelles that contain hydrolytic enzymes
• Hydrolytic enzymes in lysosomes


  • Proteases (break down proteins)
  • Nucleases (break down nucleic acids)
  • Lipases (break down lipids)
  • Glucosidases (break down carbohydrates)
• Autophagy


  Lysosomes break down worn-out organelles
• Autolysis


  Lysosomes break down all macromolecule components of severely damaged cells
• Peroxisomes


  • Contain catalase and oxidase enzymes to break down hydrogen peroxide
  • Involved in fatty acid metabolism and lipid synthesis
  • Involved in alcohol metabolism
• Mitochondria


  Site of ATP synthesis via oxidative phosphorylation and other metabolic reactions
• Metabolic reactions in mitochondria


  • Krebs cycle
  • Heme synthesis
  • Urea cycle
  • Gluconeogenesis
  • Ketogenesis
• Mitochondrial DNA


  Inherited from mother, can encode some mitochondrial proteins