Eurkayotes

• What defines eukaryotic cells?


  They have a clearly defined nucleus
• What are the characteristics of eukaryotic cells?


  1. Membrane-bound nucleus
  2. Membrane-bound organelles
  3. Multiple linear chromosomes
• How do eukaryotic cells differ from prokaryotic cells?


  Eukaryotic cells are more complex and have membrane-bound organelles
• What is the role of the cell membrane in eukaryotic cells?


  • Holds the cell together
  • Regulates transportation of substances
  • Maintains stable internal environment
• What are the characteristics of the cell membrane?


  • Selectively permeable
  • Amphipathic phospholipid bilayer
• What does it mean for the cell membrane to be selectively permeable?


  It actively transports certain materials into or out of the cell
• What is the structure of phospholipids in the cell membrane?


  They have a hydrophilic head and a hydrophobic tail
• What are the functions of proteins in the cell membrane?


  • Molecule transport
  • Enzymatic activity
• What are integral proteins in the cell membrane?


  Proteins that run completely through the bilayer
• What is the role of cholesterol in the cell membrane?


  It stabilizes phospholipid interactions and maintains membrane fluidity
• What is the Fluid Mosaic Model?


  • Describes the structure of the cell membrane
  • Composed of a phospholipid bilayer with embedded proteins
• What are the parts of the nucleus?

  • Nuclear envelope
  • DNA (chromatin and chromosome phases)
  • Nucleolus
• What is the function of the nuclear envelope?


  It separates the nucleus from the cytoplasm
• What happens to DNA during the chromatin phase?


  It is loose and spread out, allowing transcription
• What is the role of the nucleolus?


  It makes ribosomal RNA (rRNA) and proteins
• What are purines and pyrimidines?


  • Purines: Double carbon-nitrogen ring with four nitrogen atoms
  • Pyrimidines: Single carbon-nitrogen ring with two nitrogen atoms
• How do purines and pyrimidines interact in DNA?


  Purines form hydrogen bonds with corresponding pyrimidines
• What is the backbone of each DNA strand made of?


  A sugar-phosphate chain
• What is the chromatin phase of DNA?


  In the chromatin phase, the DNA is string-like and can be transcribed to make proteins.
• What happens to DNA during the chromosome phase?


  During the chromosome phase, the DNA coils around histones to organize itself.
• Why is the coiling of DNA important during cell division?


  The coiling helps to organize the DNA for correct distribution during nuclear and cell division.
• What is the function of the nucleolus?


  The nucleolus functions to make ribosomal RNA (rRNA) and proteins for ribosomes.
• What are purines and pyrimidines?


  Purines and pyrimidines are the two families of nitrogenous bases that make up nucleic acids.
• What forms the backbone of each DNA strand?


  The backbone of each DNA strand is made up of a sugar-phosphate chain.
• How are purines and pyrimidines structured?


  Purines have a double carbon-nitrogen ring, while pyrimidines have a single carbon-nitrogen ring.
• What is the significance of base pairing in DNA?


  Base pairing holds the two strands of DNA together through hydrogen bonds.
• Why can base pairings be easily separated?


  Base pairings can be easily separated because hydrogen bonds are not as strong as covalent bonds.
• What is Chargaff's Rule?


  Chargaff's Rule states that purines always bind with pyrimidines in a constant ratio within a DNA molecule.
• What are the two main types of purines?


  The two main types of purines are Adenine and Guanine.
• What are the three main types of pyrimidines?


  The three main types of pyrimidines are Cytosine, Uracil, and Thymine.
• Which pyrimidine exists in both DNA and RNA?


  Cytosine is the only pyrimidine that exists in both DNA and RNA.
• Which nitrogenous bases pair together in DNA?


  Adenine pairs with Thymine and Guanine pairs with Cytosine.
• How many hydrogen bonds form between Adenine and Thymine?


  Two hydrogen bonds form between Adenine and Thymine.
• How many hydrogen bonds form between Guanine and Cytosine?


  Three hydrogen bonds form between Guanine and Cytosine.
• What is the primary function of ribosomes?


  Ribosomes are the sites of protein synthesis in the cell.
• What are the two types of ribosomes based on their location in the cell?

  1. Free Ribosomes: Float freely in the cytoplasm, producing proteins that stay in the cell.
  2. Bound Ribosomes: Attached to the Rough Endoplasmic Reticulum, synthesizing proteins that leave the cell.
• What is the Endomembrane System?


  • A group of membranes and organelles in eukaryotic cells.
  • Works together to modify, package, and transport lipids and proteins.
• What is the largest organelle in the cell?

  The Endoplasmic Reticulum (ER) is the largest organelle in the cell.
• What are the functions of the Endoplasmic Reticulum (ER)?


  • Protein synthesis and transport
  • Protein folding
  • Lipid and steroid synthesis
  • Carbohydrate metabolism
  • Calcium storage
• What is the structure of the Endoplasmic Reticulum?


  The ER is composed of a network of small tubes called cisternae.