Why is shape important in Biology?

Shape 13. What are some similarities and differences between nucleic acid structures and protein structures?


Uses of Nucleic Acid

Nucleic acids are used for more than genetic information and as energy carriers. As you explore the following interactive, look for similarities to proteins.




 Uses of Nucleic Acids: What did you learn about the uses of nucleic acids? Complete this graphic organizer.


 RNA World

 three molecules. On the left is a molecule with a horizontal double helix above a pair of helices. In the middle is a molecule made of double helices making a silhouette of a keyhole. On the right is a molecule made of two double helices making a donut shape.

Ribozymes show a wide variety of functions with similar shapes to proteins. Left: leadzyme, Middle: hammerhead ribozyme, Right: twister ribozyme


The examples of RNA you have seen so far are involved in making proteins. But, as Canadian molecular biologist Sidney Altman discovered, RNA is used in a surprising variety of functions. It’s used as the genetic molecule in many viruses. Even though there are only 4 nucleotides available compared to 20 amino acids for proteins, RNA can perform a wide variety of chemical reactions. It can also be used to turn off genes. Controlling genes happens naturally and is also being considered as a way of treating certain diseases.


Why is shape important in Biology?


Try searching for a way that RNA is used other than for making protein. Does this use involve double strand RNA or single stranded RNA? How is this structure important in how RNA is used? We will do a share-around with the class.


Energy Transfer in Human Populations

Energy in cells and organisms is carried and stored in different forms. In autotrophs, like plants, sunlight energy is captured first as ATP.  Some of that energy is stored in other macronutrients, like carbohydrates and lipids. The energy in these macronutrients is released in all organisms by enzymes in the form of ATP.

In human populations, food systems describing how we have obtained food, have changed.

This is a graph. 

 Hunter-gatherer societies collect and hunt for food from their local environment. Herders tend for groups of domesticated animals. Shifting farming involves clearing land for cultivation over a short period of time before moving on to another location. Traditional farming involves using horses and other animals to move simple machines that help in farming. Modern farming involves using fossil-fuel burning machines and climate-controlled environments to raise crops and livestock.

In the beginning, the amount of energy we could get from food was limited by how much food we could catch or pick. With each technological improvement, the population size increased. Also, other forms of energy come into play in food production. Human strength was replaced by horsepower. 

In Canada, large amounts of energy are put into modern agricultural practices. Today, most of the energy used comes from fossil fuels.  

An infographic showing the food system cycle: growing foods then harvesting them then packaging then transporting then retailing to eating to disposing and back to growing food. 


The fossil energy put into growing, transporting, processing foods is about 5 times greater than the energy we get out of the foods grown.                 Data from the United States is similar to food energy use in Canada. The amount of energy we put into making food is broken down for different stages in the food system  Energy here is measured in BTU (British Thermal Units) which is approximately equivalent to 1 kJ.




by Center for Sustainable Systems, University of Michigan

How does energy move in food systems?

According to Statistics Canada, different foods require different amounts of energy input. 

A bar graph displaying energy input required for a variety of foods. percent energy is displayed for each bar. The bars read, from left to right: Prepared foods 19%, Dairy and eggs 18%, Grain products 13%, Fresh and frozen meat 14%, Beverages 9%, Fresh fruit and vegetables 12%, Other 6%, Condiments 5%, Fish 4%. The energy used to produce different foods in Canada




Energy 2. Would you consider eating less energy intensive food? Why or why not?


The amount of food energy we can get is limited for different reasons. Watch this video to learn more about the global food system. What are the four limitations to the food system today?

How does energy move in food systems?

Choose one of the four limitations to our food system described in the video. Explain how it could affect the way you or other people will be able to eat in the future. Describe which part of the food system (transportation, waste management, etc.) could change to allow quality food production in the future? Post your ideas in the comment section below… Using good Collaboration skills,  reply to a classmate’s explanation. Share a way the limitation they described could be overcome by connecting to specific details of the ideas or concepts they used.


Take this quiz to check your understanding of nucleic acids.


In summary, this Activity explored the big idea that the structure of biological molecules is important to their cellular functions. Specifically,
  • nucleic acids are made of three-part monomers; 
  • nucleic acids have a variety of uses in cells; 
  • energy in the form of ATP is used in biological processes;
  • populations can change because of different factors and food systems.

Nucleic Acids Graphic Organizer

You are now ready to summarize the important details from this Activity. You will be sharing this work with your teacher at the end of this Unit.  Using good details, show how the function of different nucleic acids is connected to their structure. Practice your Initiative Skills by choosing seeking to improve your graphic organizer.  Remember that your connections should:

  • be meaningful;
  • be well-organized and easy-to-follow;
  • show your understanding of the vocabulary.

Use the ideas of…

  • Structure (functional groups, shape); 
  • Monomer;
  • Linkage;
  • Properties;
  • Functions;
nucleotide phosphodiester bond nitrogenous base
ribose deoxyribose ATP
cAMP potential energy double helix
autotroph heterotroph food system