Chapter 6 Review (test)

• What is the basic unit of life?

  Cells
• Why are cells small?

  To maintain a high surface area to volume ratio for efficient diffusion
• What is cell compartmentalization and its advantages?

  • Internal division of space into sections
  • Allows distinct internal chemistry
  • Provides internal surface area for membrane-bound enzymes
• What separates the cytoplasm from the cell exterior?

  The cell membrane
• What is the role of DNA in cells?

  It contains genetic information necessary for cell function and replication
• What is the process by which genes in DNA are transcribed?


  Transcription into messenger RNA
• What is the function of ribosomes?

  To translate messenger RNA into proteins
• What are enzymes and their role in the cell?

  Enzymes are proteins that control the cell's metabolism
• Compare and contrast prokaryotic and eukaryotic cells.


  Prokaryotic Cells:

  • Small and simple
  • No nucleus
  • Circular chromosome
  • Contains plasmids

  
  

  Eukaryotic Cells:

  • Larger and complex
  • Has a nucleus
  • Multiple linear chromosomes
  • Contains membrane-bound organelles
• What is the defining feature of eukaryotic cells?


  The presence of mitochondria
• How does cell size relate to surface area and volume?

  A smaller cell has a higher surface area to volume ratio than a larger cell
• Why do larger cells have a lower surface area to volume ratio?


  As an object gets larger, its volume increases faster than its surface area
• Why do organisms need to increase surface area in certain tissues?

  To enhance diffusion of molecules or heat
• How do organisms increase surface area in tissues?


  • Thin sheets of tissue (e.g., fish gills)
  • Large flat structures (e.g., elephant ears)
  • Highly folded surfaces (e.g., internal membranes of mitochondria)
• Why are there no small-sized marine mammals?


  Small marine mammals lose heat too quickly due to high surface area to volume ratio
• What is cellular compartmentalization?

  It is the internal division of a cell into distinct sections
• What is the endomembrane system?


  A dynamic system of internal membranes and compartments in eukaryotic cells
• What is the origin of mitochondria and chloroplasts?


  They originated through endosymbiosis
• What evidence supports the endosymbiotic theory?


  Mitochondria and chloroplasts have their own circular DNA and replicate through binary fission
• What is the function of the nucleus?


  To store and protect genetic information
• What is the structure of ribosomes?


  Ribosomes consist of a large subunit and a small subunit made of ribosomal RNA and protein
• Where can ribosomes be found in a eukaryotic cell?


  Ribosomes can be free in the cytoplasm or bound to the rough endoplasmic reticulum
• What happens to ribosomes during protein targeting?

  Ribosomes migrate to the endoplasmic reticulum to become bound if their proteins are destined for vesicles
• Describe the structure and function of the nucleus.


  • Stores and protects genetic information (DNA)
  • Surrounded by a nuclear membrane with pores
  • Contains nucleolus for ribosome assembly
  • DNA exists as chromatin when not dividing
• Describe the structure and function of ribosomes.


  • Composed of ribosomal RNA and protein
  • Consists of a large and small subunit
  • Reads mRNA and translates it into amino acid sequences
• What are the two locations within a eukaryotic cell where ribosomes can be found?


  • Free ribosomes in the cytoplasm
  • Bound ribosomes on the rough endoplasmic reticulum
• What is the process of protein synthesis?


  1. Ribosomes read mRNA
  2. Translate mRNA into amino acids
  3. Form primary structure of proteins
• What are ribosomes composed of?


  Ribosomal RNA and protein
• What are the two subunits of ribosomes?


  A large subunit and a small subunit
• What is the primary function of ribosomes?

  To read messenger RNA and translate it into amino acids
• Where can ribosomes be found in a eukaryotic cell?

  Free in the cytoplasm or bound to the rough ER
• What are free ribosomes and where are they located?


  Free ribosomes float freely within the cytoplasm
• What are bound ribosomes and where are they located?


  Bound ribosomes are connected to the membrane of the rough ER
• What process do ribosomes undergo to become bound to the ER?


  Protein targeting
• What happens to proteins synthesized by ribosomes that are destined for vesicles?


  They migrate to the ER to become bound ribosomes
• What is the primary function of mitochondria?


  Converting food energy into ATP
• What is the matrix in mitochondria?


  The cytoplasm of the mitochondria containing enzymes for the Krebs cycle
• What is the significance of the inner membrane of mitochondria being highly folded?


  It increases surface area for ATP synthesis
• What are the two forms of the endoplasmic reticulum (ER)?


  Rough ER and smooth ER
• What distinguishes rough ER from smooth ER?


  Rough ER is studded with ribosomes, while smooth ER is not