The Central Dogma of DNA
• The process of making proteins in a
cell!
DNA
RNA
Protein
Done in 2 steps: Transcription and Translation
RNA
• Ribonucleic Acid
• RNA is a molecule that helps synthesize
(make) proteins
• There are 3 kinds of RNA:
mRNA, tRNA, rRNA
• In RNA A pairs with U (there is
no thymine)
DNA
RNA
The sugar is
Deoxyribose
Double stranded
The sugar is Ribose
Bases = T, A, C, G
Bases = U, A, C, G
DNA never leaves
the nucleus
RNA can leave the
nucleus
Single stranded
The Central Dogma of DNA
Part 1 - Transcription
So you’ve managed to sneak into
the Cheeto’s factory and have
found the safe where they hide
the secret recipe to make the
“hotness” for the Hot Cheetos
You only have 45 seconds before
the alarm sounds and the
security guards find you. YOU
NEED THIS RECIPE!
What are you going to do?
WRITE IT DOWN!
So you write it down, but when you get back home,
you realize that the recipe is in Chinese
What do you do?
Have someone translate it
into English!
- 3 Tomatoes
- 4 Tbsp Pepper
- 5 cups of salt
Now you can make any
Cheeto HOT!
What steps did we just do...
1. Write the recipe down
2. Translate the recipe
This is exactly what happens when DNA is used to
make proteins
Review: What is a protein?
• Made of amino acids:
• Polypeptide
- Amino acids linked together
- A protein
Labeling DNA Strands: 5’ vs 3’
 DNA strands are labeled as follows:
Strand 1: 5’ ATCGTA 3’
Strand 2: __ ______ __
The Central Dogma of DNA
• The process of making proteins in a
cell!
Transcription
DNA
RNA
Translation
Protein
2 Steps:
1. Transcription:
Making a copy of
the desired gene
using mRNA
2. Translation: mRNA
is used to make
the protein with
the help of
ribosomes
Central Dogma Song
Step 1
DNA
RNA
Transcription
Transcription
 RNA reads and copies the
DNA code
This occurs in the NUCLEUS
of the cell
Rules to write the mRNA
complimentary strand:
Rule: A pairs with U “Aunt-Uncle”
C pairs with G “Chewing Gum”
• DNA: 5’ A T C G A T 3’
• mRNA: 3’ _ _ _ _ _ _ 5’
Checking for Understanding
Your turn…
1. DNA: GGATCCATGTTC
mRNA:
2. DNA: TATGCGAAACAT
mRNA:
Steps of Transcription:
1. DNA untwists and opens
2. DNA is copied into mRNA with the help of
RNA Polymerase
3. mRNA travels out of the nucleus to the
rough E.R.
What is mRNA?
• mRNA = messenger RNA
• The type of RNA that delivers the code
from the DNA to the ribosomes!
Exit Slip #1
The central dogma of DNA states that RNA is
made from DNA. This process is called:
A translation
B central dogma
C transcription
D replication
Exit Slip #2
Step 2
DNA
RNA
Transcription
Protein
Translation
Translation/Codons
 Translation: The process of converting RNA
into PROTEIN
 THREE nucleotides (bases) on an mRNA
sequence is called a codon
 One codon codes for one amino acid
– Ex:
mRNA: AUG-CUU-CUC
3 codons  3 amino acids
AUCCUCCGC
CODON
CFU
1. How many bases, codons, and amino acids are in the following
mRNA sequence?
AUG-AUG-AGG-CGG-CAA-UUU
bases:________
codons:_______ amino acids:________
2. Which statement best explains how messenger RNA (mRNA)
provides a code for the formation of a protein?
a. One base in the RNA codes for three amino acids in the
protein
b. Three bases in the RNA code for one amino acid in the protein
Translation video
Translation Steps
(RNA  Protein)
mRNA travels out of the nucleus to
Rough E.R./Ribosomes
ribosomes and tRNA link together
amino acids to make a protein
Transfer RNA (tRNA)
tRNA is responsible for delivering the
amino acids
tRNA has an anticodon
• three bases on tRNA that match up to the
codon on the mRNA sequence
These are
all amino
acids!
Find the amino acid sequence using the
given DNA sequence and Codon Box that
is provided
DNA: TAC-TTT-GTG-GTC-AAA-ATT
mRNA: AUG-AAA-CAC-CAG-UUU-UAA
Protein: Met-Lus-His-Gln-Phe-Stop
http://www.stolaf.edu/people/giannini/flash
animat/molgenetics/translation.swf
EXIT SLIP #1
1. What is the amino acid sequence for the
DNA sequence :
ATGCCCGTTATC
A
B
C
D
pro-leu-met-stop
tyr-gly-gln-stop
met-pro-tyr-gly
not enough information
Exit Slip #2
2. In the DNA sequence below, how many
amino acids are coded for?
5’ ATGGGCTACGTTATA 3’
A
B
C
D
3
2
5
0
WEDNESDAY: Textbook Questions
Directions: Use Chapter 8.4 (pages 239-242) to answer the
following questions
.
THURSDAY: Multiple-Choice Questions
Directions: Write five multiple-choice questions that could be used on the quiz. Make
them creative and challenging. Each question should have four choices (a-d).
Question #1:
______________________________________________________________________
a) _______________________________________________________________
b) _______________________________________________________________
c) _______________________________________________________________
d) _______________________________________________________________
Central Dogma Race!
mRNA
AAA
Complement
ary
TTT ATG
AAA UAC
Amino Acids
(2)
Lys-Tyr
GTT
GCG CAA
CGC GUU
Arg-Val
ATC
TAG GCG
AUC CGC
Lle-Arg
AGC CTT
TCG GAA
AGC CUU
Ser-Leu
TAC ATG
ATG TAC
UAC AUG
Tyr-Met
The Code
12.Each codon codes for a specific amino acid
CUUCUACGC
– Ex) CUU = leucine
13.There are only 20 different amino acids
used to make millions of different proteins
14. It’s all about the sequence (order) of amino
acids!
The Final Product: Protein
19.Once all the amino acids are linked
together, a protein is formed
20.Protein = many amino acids = polypeptide
21.Why do we need proteins?
A) Structure: Fingernails, Hair, Cells
B) ENZYMES! - to speed up chemical reactions
Guided Practice
We are going to Transcribe and Translate
DNA into mRNA into Amino Acids
RNA ____________
Polymerase inside the
Step 1) Act as the enzyme _____
transcribe this DNA into mRNA:
nucleus and _____________
3’ T A C T T T C A G G G T C A C A C T 5’
5’ A T C A A A G T C C C A G T G T G A 3’
5‘ A U G A A A G U C C C A G U G U G A 3’
mRNA _______________________________________
Guided Practice Continued
ribosome the organelle that
Step 2) Act as a ______________,
translate
________________
mRNA into amino acids in the
cytoplasm
__________________
of the cell.
5’ A U G A A A G U C C C A G U G U G A 3’
Break it down into Codons: UAG, AAA, GUC, CCA, GUG, UGA
Now use the Codon Table to translate the amino acids
Your amino acids are:
____________
(always START)
Methionine
____________
Lysine
____________
Valine
Proline
____________
Valine
____________
stop codon
____________
(need an end)