Question

carbon - based molecules: the building blocks of life
background information:
from the smallest single - celled organism to the tallest tree, all life depends on the properties and reactions of four classes of carbon - based compounds—carbohydrates, lipids, proteins, and nucleic acids. we will spend an entire unit later in the year on nucleic acids. carbohydrates, lipids, and proteins are the 3 building blocks of all living things that we will focus on this unit. these are called macromolecules because they are large molecules. they are responsible for most of the structure and functions of the body, including energy storage, insulation, growth, repair, and communication. simple organic molecules can be joined together to form all the essential biological molecules needed for life.
model 1: introduction to macromolecules
using your carbon - based molecule building cards and molecular modeling kits, build the following molecules and complete the table and answer the questions that follow.

macromolecule	example molecule(s)	atoms (elements) found in molecule
lipid
protein

questions:

1. a complete carbohydrate is macromolecule. this means that it is a large or small molecule. (circle one)
2. based on your table, what three elements do all macromolecules have in common?
3. is glucose, a sugar molecule, able to provide the necessary elements needed to build a lipid and a protein? if not, what element was missing, and how do you think organisms get that element?
4. in order for you to get the atoms you needed to build the lipids and proteins what did you have to do to the bonds that hold together the atoms in glucose?

Explanation:

Step1: Define macromolecule

Macromolecules are large molecules. Since carbohydrates are macromolecules, they are large.

Step2: Identify common elements

Carbohydrates, lipids, and proteins all contain carbon, hydrogen, and oxygen.

Step3: Analyze glucose composition

Glucose has the formula $C_6H_{12}O_6$. Lipids may have additional elements like phosphorus in phospholipids and proteins have nitrogen in their amino - acid structure which glucose lacks.

Step4: Consider chemical processes

Atoms in glucose need to be rearranged through chemical reactions to form lipids and proteins, which requires breaking and forming new chemical bonds.

Answer:

1. LARGE
2. Carbon, Hydrogen, Oxygen
3. Glucose cannot provide all the necessary elements to build a lipid and a protein. For lipids, glucose lacks a significant amount of the element phosphorus in some complex lipids like phospholipids. For proteins, glucose lacks nitrogen. Organisms obtain phosphorus from the soil (for plants) or by consuming plants or other organisms that have absorbed phosphorus. Organisms obtain nitrogen from the atmosphere (in the case of nitrogen - fixing bacteria) or by consuming nitrogen - rich foods like proteins in their diet.
4. Chemical reactions are needed to break the bonds in glucose and rearrange the atoms to build lipids and proteins.