B1.1  Carbohydrates and Lipids

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.

• In what ways do variations in form allow diversity of function in carbohydrates and lipids?
• How do carbohydrates and lipids compare as energy storage compounds?

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

• How can compounds synthesized by living organisms accumulate and become carbon sinks?
• What are the roles of oxidation and reduction in biological systems?

Resources:

• At SHS, Topic B1.1 is taught in the Membrane Structure, Carbs and Lipids and Reproductive Hormones unit. 
• Quizlet study set for this topic.  Coming soon!
• View the general sequence of the SHS course
• View the SHS units mapped to the IB Biology curriculum roadmap

B1.1.1— Chemical properties of a carbon atom allowing for the formation of diverse compounds upon which life is based.

• Outline the number and type of bonds carbon can form with other atoms.
• Outline the cause and consequence of covalent bonds between atoms.
• Recognize common functional groups.
• List the four major classes of carbon compounds used by living organisms.
• List example molecules with branched chain, unbranched chain, single ring or multiple rings.​

B1.1.2— Production of macromolecules by condensation reactions that link monomers to form a polymer.  

• Define monomer and polymer.
• Describe condensation reactions.
• State that energy from ATP is needed to produce macromolecules by condensation reactions.
• Outline the condensation reactions that form polysaccharides, polypeptides and nucleic acids.

B1.1.3— Digestion of polymers into monomers by hydrolysis reactions.

• Define monomer and polymer.
• Describe hydrolysis reactions.
• Outline the hydrolysis reactions that digest polysaccharides, polypeptides and nucleic acids.

B1.1.4— Form and function of monosaccharides.

• Define monosaccharide.  
• Identify pentose and hexose carbohydrates from molecular diagrams.  
• Outline the properties of glucose referring to solubility, transportability, stability, and energy yield from oxidation. ​

B1.1.5— Polysaccharides as energy storage compounds.

• Define polysaccharide.  
• Compare the structure and function of amylose, amylopectin, and glycogen.
• Discuss the benefit of polysaccharide coiling and branching during polymerization.
• Explain how condensation or hydrolysis of alpha-glucose monomers build or mobilize energy stores.​

B1.1.6- Structure of cellulose related to its function as a structural polysaccharide in plants.  

• Compare the structure of alpha-glucose and beta-glucose. 
• Describe the structure of cellulose microfibrils. 
• Discuss the consequences of the strength of cellulose in the plant cell wall.

B1.1.7— Role of glycoproteins in cell–cell recognition. 

• State the function  of glycoproteins in the cell membrane. 
• Compare the structure of the A, B and O glycoproteins on the red blood cell membrane.
• Discuss the consequences of the presence of A, B and O glycoproteins during blood transfusion.

B1.1.8- Hydrophobic properties of lipids.

• Explain why lipids are hydrophobic.
• Outline the structure and function of fats, oils, waxes and steroids.

B1.1.9- Formation of triglycerides and phospholipids by condensation reactions.

• Explain the  condensation reaction connecting fatty acids and glycerol to form a triglyceride.
• Explain the  condensation reaction connecting fatty acids, glycerol and a phosphate group to form a phospholipid. 

B1.1.10- Difference between saturated, monounsaturated and polyunsaturated fatty acids.

• Describe the structure of a generalized fatty acid.
• Compare and contrast the structures and properties of saturated and unsaturated (mono- or poly-) fatty acids.
• Distinguish between the structure and properties of cis- and trans-unsaturated fatty acids.

B1.1.11- Triglycerides in adipose tissues for energy storage and thermal insulation. 

• Outline properties of triglycerides that make them suitable for long-term energy storage. 
• State the function of adipose tissue.
• Discuss the adaptation of a thick adipose tissue layer as a thermal insulator. 

B1.1.12- Formation of phospholipid bilayers as a consequence of the hydrophobic and hydrophilic regions.

• Draw a simplified diagram of the structure of the phospholipid, including a phosphate-glycerol head and two fatty acid tails.
• Define hydrophilic, hydrophobic and amphipathic.
• Outline the amphipathic properties of a  phospholipid.
• Explain why phospholipids form bilayers in water, with reference to hydrophilic phosphate heads and two hydrophobic hydrocarbon tails.

B1.1.13- Ability of non-polar steroids to pass through the phospholipid bilayer.  

• Identify steroid molecules from molecular diagrams.  
• State why steroid hormones are able to pass directly through the phospholipid bilayer.