From Gene to Protein—Transcription and Translation Student Worksheet | All Answers are 100% Correct

From Gene to Protein – Transcription and Translationi
How do the genes in our DNA influence our characteristics?

A gene is a segment of DNA that provides the instructions for making a protein. Proteins influence
our characteristics. This chart shows an example.
Gene in DNA  Protein  Characteristic


 

One version of a gene provides Normal enzyme makes the
Normal skin and hair
instructions to make normal protein  pigment molecule in skin 
color
enzyme. and hair.
Another version of the gene provides Defective enzyme does not
Albinism (very pale
instructions to make defective protein  make this pigment 
skin and hair)
enzyme. molecule.
1. How can a gene result in albinism? (Give a molecular explanation.)
For example, the defective enzyme that results in albinism has a different amino acid
sequence than the normal enzyme for synthesizing melanin. A gene directs the synthesis
of a protein by a two-step process. First, the instructions in the gene in the DNA are copied
into a messenger RNA (mRNA) molecule.


How does a gene provide the instructions for making a protein?
A two-step process:
The first step is transcription of the gene in the DNA.
Transcription produces messenger RNA (mRNA).


The second step is translation of the mRNA molecule.
Translation produces proteins.


During transcription, the sequence of nucleotides
in a gene in the DNA is copied to a corresponding
sequence of nucleotides in mRNA.

During translation, the sequence of nucleotides in
mRNA determines the sequence of amino acids in
the protein. The sequence of amino acids
determines the structure and function of the
protein.

2. Label the DNA, mRNA and protein molecules in
this figure. Draw a rectangle around a nucleotide.
Draw a circle around an amino acid.
3. Which process takes place in the nucleus? ___ transcription ___ translation
Explain why this process must occur in the nucleus.
Transcription takes place in the nucleus. It uses DNA as a template to make an RNA
molecule. RNA then leaves the nucleus and goes to a ribosome in the cytoplasm,
where translation occurs. Translation reads the genetic code in mRNA and makes 1a
protein.

, 4. Complete this flowchart to describe how a gene directs the synthesis of a protein. Label the process
represented by each arrow and fill in the blank with the name of the appropriate molecule.

Gene in DNA RNA
___________ protein

5. Complete the following sentence to describe how different versions of a gene can result in normal
skin and hair color vs. albinism.
nucleotides
Differences in the sequence of _____________________ in a gene
nucleotides
result in differences in the sequence of ______________________ in mRNA which
amino acids
result in differences in the sequence of _______________________ in the protein which
result in normal vs. defective enzyme to make the pigment in skin and hair which
albinism
can result in normal skin and hair color vs. ___________________.
6. In this activity, you will model how a cell carries out transcription and translation to make the
beginning of the hemoglobin molecule. What type of molecule is hemoglobin?


Transcription
During transcription, the enzyme, RNA polymerase:
 separates the two strands of a DNA double
helix and
 makes an mRNA molecule by adding RNA
nucleotides, one at a time.

7. In the figure, write enzyme next to the name of the
enzyme. Trace the outlines of the DNA molecule.

Each DNA nucleotide in the gene is matched with a
complementary RNA nucleotide which has a
matching shape and charge distribution.

The base-pairing rules summarize which nucleotides
are complementary. The base-pairing rules for
transcription are similar to the base-pairing rules in
The template strand of the DNA contains the gene that is
the DNA double helix.
being transcribed. A = adenine; C = cytosine; G = guanine;
T (in DNA) = thymine; U (in RNA) = uracil

8a. Use the information in the above figure to complete this table.
Base-Pairing Rules for Complementary Nucleotides:
between the two strands between DNA and RNA
of a DNA double helix (during transcription)
G pairs with C. C
G pairs with ____.
A
T in DNA pairs with ____ in RNA.
T pairs with A.
A in DNA pairs with ____
U in RNA.

8b. Which nucleotide will be the next nucleotide to be joined to the growing mRNA molecule in the
figure above? T__ A __ G C __ C G __ A T __ AU
The base-pairing rules ensure that the nucleotide sequence in the gene in the DNA is copied into a
corresponding nucleotide sequence in the mRNA molecule.
2