B2.2  Organelles and Compartmentalization

Theme:  Form and Function

Organelle structure creates specialized cellular functions through compartmentalization that separates and optimizes different biological processes.

• Nuclear compartmentalization separates transcription from translation, allowing mRNA modification before meeting ribosomes.
• Compartmentalization concentrates enzymes and metabolites while separating incompatible processes, as seen in lysosomes that isolate digestive enzymes from cellular components.
  
• Mitochondrial adaptations maximize ATP production.
• Chloroplast adaptations maximize capture of light energy for conversion into chemical energy.
  
• Ribosome location determines protein fate.
  
• Golgi apparatus structure enables sequential protein processing and packaging.
  
• Vesicle structure with clathrin coating enables targeted cellular transport.

Guiding Questions:  
Guiding questions help students view the content of the syllabus through the conceptual lenses of both the themes and the levels of biological organization.

• How are organelles in cells adapted to their functions?
• What are the advantages of compartmentalization in cells? 

​​Linking Questions:  
Linking questions strengthen students’ understanding by making connections between topics.  The ideal outcome of the linking questions is networked knowledge.

• What are examples of structure–function correlations at each level of biological organization?
• What separation techniques are used by biologists?

Key Terms to Know: * higher level only

Adenosine Triphosphate (ATP)*
Aerobic Cellular Respiration*
Bound Ribosome*
Calvin Cycle*
Cell Fractionation
Cell Wall
Chloroplast*
Clathrin*
Compartmentalization
Cristae*
Cytoplasm
Cytoskeleton
Double Membrane*
Enzyme
Eukaryote
Free Ribosome*

Golgi Apparatus*
Intermembrane Space*
Krebs Cycle*
Lysosome
Matrix (of Mitochondrion)*
Meiosis
Metabolite
Mitochondrion*
Mitosis
mRNA
Nuclear Pore*
Nucleus
Organelle
Phagocytic Vacuole
Photosystem*
Photosynthesis*

Plasma Membrane
Post-Transcriptional Modification
Prokaryote
Protein*
Ribosome
Rough Endoplasmic Reticulum*
Secretion*
Stroma*
Substrate*
Surface Area*
Thylakoid Membrane*
Transcription
Translation
Ultracentrifuge
Vesicle

B2.2.1— Organelles as discrete subunits of cells that are adapted to perform specific functions.

• Define organelle as a discrete structure within a cell that is adapted to perform a specific function. 
• List solid organelles and those enclosed by a single membrane and a double membrane. 
• Outline the reason why the cell wall, cytoskeleton and cytoplasm are not considered to be organelles. ​

B2.2.2— Advantage of the separation of the nucleus and cytoplasm into separate compartments.

• Outline the benefits of DNA in the nucleus being compartmentalized from the cytoplasm.
  
• Compare the location and timing of initiation of transcription and translation between prokaryotic and eukaryotic cells.
• Outline why post-transcriptional modification of RNA is not possible in prokaryotic cells.

B2.2.3-- Advantages of compartmentalization in the cytoplasm of cells.

• State the meaning “compartmentalization” within cells.
• List advantages of compartmentalization within cells. 
• Outline the benefit of compartmentalization of lysosomes and phagocytic vacuoles in cells. 

AHL ​​B2.2.4— Adaptations of the mitochondrion for production of ATP by aerobic cell respiration.

• Draw and label a diagram of a mitochondrion.
• Describe how the following mitochondrial structures are adapted to their function:  outer membrane, inner membrane, intermembrane space, cristae, matrix, ribosome and mtDNA.​

AHL ​​B2.2.5— Adaptations of the chloroplast for photosynthesis.

• Draw and label a diagram of a chloroplast.
• Describe how the following chloroplast structures are adapted to their function:  double membrane, thylakoid membrane, photosystems, compact thylakoid lumen, stroma, ribosome and cpDNA.​

AHL ​​B2.2.6- Functional benefits of the double membrane of the nucleus.

• Describe the structure and function of the pores in the nuclear membrane.
• ​Describe the breakdown and reformation of the nucleus during mitosis.
  

AHL ​​B2.2.7— Structure and function of free ribosomes and of the rough endoplasmic reticulum.

• Outline the structure of ribosomes.
  
• Compare the structure and function of free ribosomes and those bound to the rough endoplasmic reticulum. 
• Compare the ultimate destination(s) of proteins synthesized at  free ribosomes to those synthesized at ribosomes bound to the rough endoplasmic reticulum.

AHL ​​B2.2.8- Structure and function of the Golgi apparatus.

• Outline the structure and function of the Golgi apparatus. 
• Outline the general flow of proteins to, through and from the Golgi apparatus.

AHL ​​B2.2.9- Structure and function of vesicles in cells.

• Describe the formation of vesicles in cells from phospholipid membranes, including the role of clathrin.
• List functions of vesicles in cells.
• Outline the consequence of vesicle fusion.