Molecular Biology – Central Dogma
In Molecular Biology, we are taking a much closer look at the structure of DNA. We have just completed an activity on
DNA replication. This occurs prior to cell division. We examined DNA at the chromosomal level, and learned to use a
karyotype to identify whether portions of a chromosome or entire chromosomes had be deleted, moved or added to the
genotype of an individual due to errors during meiosis.
The Central Dogma is shown below:
The CENTRAL DOGMA OF MOLECULAR BIOLOGY
is a scientific doctrine (statement believed to be
true) that states that DNA can
1. use itself as a template to make more DNA
(replication)
OR
2. be utilized as a template for the transcription
of DNA to mRNA–which then serves as a
template for translation into a protein.
REPLICATION
The DNA replicates its information in a process
that involves many enzymes (you only need to
know two). Replication occurs ONLY when we
make new cells and involves using both DNA
strands as templates to make complementary
strands (semi-conservative replication.
Legend: Transcription of DNA to RNA to protein: This
dogma forms the backbone of molecular biology and is
represented by four major stages.
PROTEIN SYNTHESIS
DNA also stores the code that is required to make proteins. These codes are the genes that are on your
chromosomes. The DNA code is used as a template to create an mRNA strand during transcription.
3. In eukaryotic cells, the mRNA migrates from the nucleus to the cytoplasm.
4. Messenger RNA (mRNA) carries coded information to ribosomes. The ribosomes "read" this information
and use it for protein synthesis. This process is called translation. Transcription and translation make up the
process called protein synthesis.
DNA contains the coded Information for the production of all proteins, as well as RNA. Proteins are involved
in almost all structural and enzymatic biological activities. Proteins are a part of hormones, enzymes,
organs, muscle, bone, nerves, pigments, blood and hair found in or on the body.
We are studying the Central Dogma of Molecular Biology.
1. What is the Central Dogma (in your own words):
2. What “processes” are included in the Central Dogma. Which one(s) are related to Replication? Which
deal with protein synthesis
3. Does replication need to be completed before protein synthesis takes place?
4. How Does this unit relate to the previous unit on cell division (What knowledge are you using from the
previous unit to understand the current unit)?
5. Why is this unit called Molecular Biology?
6. What does the following statement mean (think about your answer to question 5) ? “ the translation of
a protein invariably follows a chain of molecular command”
7. Identify some key proteins in your body that are created during protein synthesis.
Protein Synthesis
HOW DO WE USE GENES AND PROTEIN EXPRESSION TO SOLVE “REAL LIFE PROBLEMS?
Transcription Translation Practice
Go to website http://learn.genetics.utah.edu/content/begin/dna/transcribe/
Complete both transcription and translation.
In the box below, write the sequence of amino acids you produced using the simulator!
Go to website http://learn.genetics.utah.edu/content/begin/dna/firefly/
Watch the animation
1. What does the luciferase enzyme do?
2. Where are the directions to make this make this enzyme stored?
3. What must happen after the luciferase polypeptide is built so it can become a FUNCTIONAL enzyme?
4.
Why do fireflies produce this glowing enzyme???