Student Portal

Genes and Proteins

Investigation 1 – PreLab









Genes are instructions that tell your body how to make all the proteins it needs to survive and grow. By identifying each of these proteins, scientists hope to better understand how your body works, and what is happening when it doesn’t work properly. They hope this knowledge will eventually lead to more effective medicines and treatments.


Genetic counselors provide information and support to individuals who have or are at risk of having birth defects or genetic conditions, as well as to their families.


This Investigation is designed to help you to answer the following Focus Questions:

  • How does DNA control the functions of an organism? 
  • Can mutations in DNA cause changes in an organism? 

Note: These questions are located in your SDR at the beginning and end of the Investigation.



As a class, read the Background(s) in the Investigation. When finished, discuss the following concept as a class:

  • DNA or deoxyribonucleic acid (dee-oxi’-ribo-nuk- lay’ ik) is a long molecule made up of chemical building blocks called nucleotides.
  • Nucleotides in DNA can contain one of four different bases: adenine (A), thymine (T), cytosine (C), and guanine (G).
  • Different combinations of these four bases make each person’s DNA unique.
  • Each molecule of DNA consists of smaller segments called genes.
  • Each gene contains the information to make one unique protein.
  • Proteins are molecules that carry out most cell functions.
  • Proteins are made up of building blocks called amino acids.
  • Cells convert the information from genes into proteins with the help of another molecule called RNA (ribonucleic acid).
  • Like DNA, RNA is made up of nucleotides with the bases adenine (A), cytosine (C), and guanine (G). However, instead of thymine (T), the fourth base in RNA is uracil (U).
  • When information is converted from DNA to RNA, there is a special set of rules that are followed:
    • A in DNA = U in RNA
    • G in DNA = C in RNA
    • C in DNA = G in RNA
    • T in DNA = A in RNA
  • After the RNA molecule is made, it acts as a messenger. It carries the code from DNA in the cell’s nucleus to the parts of the cell that make proteins.
  • Proteins are made of chains of amino acids that bend, twist, and fold to form a three-dimensional structure that is unique to each protein.
  • The RNA code must be “translated” into a protein. This occurs on structures called ribosomes.
  • To translate the RNA code into protein, the ribosome “reads” the RNA in groups of three bases called codons.
  • Each codon (group of three bases) corresponds to a specific amino acid.
  • Mutations can occur in DNA. A mutation is simply a change in the sequence of nucleosides in a gene.
  • Three basic types of mutations are
    • Substitution – One nucleoside is changed into a different nucleoside.
    • Insertion – One or more nucleosides are inserted into the DNA sequence.
    • Deletion – One or more nucleosides are removed from the DNA sequence.


The following list includes Key Terms that are introduced in the Investigation Background(s). They should be used, as appropriate, by teachers and students during everyday classroom discourse.

  • DNA
  • protein
  • amino acid
  • RNA
  • codon
  • mutation

Note: Definitions of these terms can be found on the Introduction page to the CELL.

Note: Additional words may be bolded within the Background(s). These words are not Key Terms and are strictly emphasized for exposure at this time.


  • Complete the Recall section in your SDR. 
    • What do you know about DNA?
    • What functions of a cell does DNA control?
    • What do you know about RNA?
    • What functions do proteins have?
  • Play the video below. Remember to follow along with your SDR and make any notes that you think might be helpful.
  • After the video, divide into lab groups to discuss strategy for the lab. For example, you may assign certain group members to perform specific functions during the lab.

Note: The purpose of the video is to allow you to anticipate the laboratory experience you will soon encounter. You should leave this PreLab session with a firm idea of what to expect and how to perform in the lab.

Note: Homework is posted below the video.


You should review the Investigation and the video in preparation for the Lab.