Cells

• What does the cell theory state?

  All organisms are composed of cells.
• What types of organisms can be unicellular?

  Amoeba and bacteria are unicellular.
• How do new cells arise?

  New cells arise from pre-existing cells.
• What has allowed us to understand cell ultrastructure?

  Advances in microscopy.
• What do eukaryotic cells contain?

  A nucleus and membrane-bound organelles.
• What additional organelles do plant cells have?

  Chloroplasts and cellulose cell walls.
• What is the function of the nucleus?

  • Contains DNA for protein synthesis
  • DNA replication occurs here
  • Transcription produces mRNA templates
• What do nuclear pores allow to transport out of the nucleus?

  mRNA and ribosomes.
• What is the role of the nuclear envelope?

  Separates the nucleus from the cytoplasm.
• What does the nucleolus produce?

  rRNA, tRNA, and ribosomes.
• What happens to chromatin before cell division?

  It condenses to form chromosomes.
• What is the function of the rough endoplasmic reticulum?

  Packaging and storing proteins.
• What does the smooth endoplasmic reticulum produce?

  Steroids and lipids.
• What is the function of the Golgi body?

  Packaging proteins for secretion.
• What do lysosomes contain?

  Digestive enzymes to break down organelles.
• What is the role of centrioles?

  Form the spindle during cell division.
• What is the primary function of mitochondria?

  ATP synthesis by aerobic respiration.
• What do chloroplasts contain for photosynthesis?

  Photosynthetic pigments to trap light energy.
• What is the function of the vacuole?

  Stores solutes and maintains turgidity.
• What is the role of ribosomes?

  Protein synthesis.
• What do plasmodesmata connect?

  Cells via cytoplasm-filled canals.
• What is the function of the cell wall?

  Provides mechanical strength and support.
• How do organelles work together in protein synthesis?

  1. Ribosomes produced in nucleolus
  2. mRNA leaves nucleus via nuclear pores
  3. mRNA attaches to ribosomes on rough ER
  4. Protein synthesis occurs at ribosomes
  5. Rough ER transports polypeptides to Golgi body
  6. Polypeptides modified in Golgi body
  7. Enzymes packaged into secretory vesicles
  8. Vesicles merge with cell membrane for exocytosis
• What are the similarities and differences between mitochondria and chloroplasts?

  Similarities:

  • Both have double membranes
  • Both have highly folded inner membranes
  • Both have circular DNA for self-replication
  • Both have ribosomes
  • Both produce ATP

  
  

  Differences:

  • Mitochondria have cristae; chloroplasts have thylakoid membranes
  • Chloroplasts contain photosynthetic pigments; mitochondria do not
  • Mitochondria have an inner matrix; chloroplasts have a stroma
• What do prokaryotic cells lack?

  Membrane-bound organelles.
• How do ribosomes differ in prokaryotic and eukaryotic cells?

  Prokaryotic ribosomes are smaller and free.
• Where is DNA located in prokaryotic cells?


  Free in the cytoplasm.
• What is the composition of the cell wall in prokaryotic cells?

  Composed of peptidoglycan.

  
• What is the function of mesosomes in prokaryotic cells?

  Used for aerobic respiration.
• What are the key differences between prokaryotic and eukaryotic cells?

  • Prokaryotic cells are smaller (1-10 µm), eukaryotic cells are larger (10-100 µm)
  • Prokaryotic ribosomes are smaller and free; eukaryotic ribosomes are larger and bound
  • Prokaryotic cells lack membrane-bound organelles; eukaryotic cells have them
  • Prokaryotic DNA is free in cytoplasm; eukaryotic DNA is in the nucleus
  • Prokaryotic cells have no nuclear envelope; eukaryotic cells have a double membrane nucleus