Cell structure and organelles

• What is the most prominent feature of a cell?

  The nucleus
• What is the structure that bounds the nucleus?

  A double membrane consisting of an inner and outer membrane
• What is contained within the nucleoplasm?


  A type of cytoplasm specific to the nucleus
• What are chromatin and their role during cell division?

  Coils of DNA that form chromosomes as they condense before cell division
• How many nucleoli can be found per nucleus?

  • 1 to 4 nucleoli per nucleus
• What is the function of the nucleolus?


  It allows for the transport of mRNA and ribosomes out of the nucleus
• What are the subunits of ribosomes formed from?

  Proteins joined to rRNA
• What is the primary function of ribosomes?

  Protein synthesis
• How are ribosomes found in the cell?


  They can be free in the cytoplasm or bound to rough endoplasmic reticulum
• What is the structure and function of the endoplasmic reticulum (ER)?


  • Large double membrane system of fluid-filled flattened sacs (cisternae)
  • Links with the Golgi body and is close to the nucleus
• What is the main function of rough endoplasmic reticulum (Rough ER)?

  Packaging and storing proteins
• Why is the rough ER called "rough"?

  Because of the ribosomes attached to it
• What is the function of smooth endoplasmic reticulum (Smooth ER)?

  Transport and production of lipids, as well as packaging and storing lipids and carbohydrates
• What are secretory vesicles?


  • Small membrane-bound sacs
  • Store and transport materials within cells
  • Move from the Golgi body to the cell surface membrane
• What happens when secretory vesicles reach the cell surface membrane?

  The membranes fuse together, and the contents of the vesicle are released
• What are lysosomes and their function?

  • Membrane-bound vesicles containing strong digestive enzymes
  • Important for phagocytosis
• What is the structure of mitochondria?

  • Double membrane
  • Inner membrane is folded into structures called cristae
• What is the main function of mitochondria?

  ATP synthesis through aerobic respiration
• What is the nuclear pore?


  • Small gaps within the double membrane of the nucleus
  • Allows for the movement of mRNA and nucleotides out of the nucleus
• What is the function of the nuclear envelope?

  It separates the contents of the nucleus from the cytoplasm
• What is the main function of the nucleus?

  It contains DNA and codes for protein synthesis, and DNA replication occurs here
• What is produced during transcription in the nucleus?

  mRNA templates
• What are the differences between chloroplasts and mitochondria?

  • Chloroplasts contain pigments such as chlorophyll
  • Chloroplasts trap light for photosynthesis
  • Chloroplasts are only found in plants
• What are centrioles and their role in cell division?

  • Microtubules that form spindles during cell division
  • Not present in basic cell organelles
• What are plasmodesmata?


  • Microscopic channels that traverse cell walls
  • Allow for transport of substances in plant cells
• What is the function of vacuoles in plant cells?

  • Contains cell sap and stores solutes such as glucose
  • Swells due to osmosis for turgidity
• What is the composition of the cell wall in plant cells?

  • High tensile strength of cellulose microfibres
  • Provides strength for cells
• How do plasmodesmata contribute to plant cell function?

  • Allow for transport of solutes
  • Facilitate cell-to-cell communication
• What do prokaryotic cells lack?

  A nucleus
• Why is DNA not wound around histone proteins in prokaryotic cells?

  Because prokaryotic cells lack a nucleus
• How is DNA found in prokaryotic cells?


  As single loops, floating free in the cytoplasm
• What type of DNA do all prokaryotic cells have?

  Circular DNA
• What do prokaryotic cells lack in terms of organelles?

  Membrane-bound organelles
• Name two examples of membrane-bound organelles that prokaryotic cells lack.

  Golgi apparatus and mitochondria
• What type of ribosomes do prokaryotic cells have?

  70s ribosomes
• How do the sizes of ribosomes in prokaryotic and eukaryotic cells compare?

  Prokaryotic ribosomes are smaller than eukaryotic ribosomes
• Where are ribosomes found in prokaryotic cells?


  Free in the cytoplasm
• What is the function of ribosomes in prokaryotic cells?


  To assemble amino acids into proteins
• What separates the plasma membrane from the rest of the cell in prokaryotic cells?

  The plasma membrane itself
• What are prokaryotic cell walls made of?

  Murein, which is a glycoprotein