1. Regents Biology
Learning Objectives
1. How is the code of DNA translated into
messenger RNA?
2. How is messenger RNA transcribed
into a protein?
3. Describe how to make a protein
(beginning with a gene).
2. Regents Biology
Bodies are made up of cells
All cells run on a set of instructions
spelled out in DNA
Bodies → Cells → DNA
3. Regents Biology
How does DNA code for cells & bodies?
how are cells and bodies made from the
instructions in DNA
DNA → Cells → Bodies
4. Regents Biology
DNA has the information to build proteins
genes
DNA → Proteins → Cells →
Bodies
proteins
cells
bodies
DNA gets all the glory,
Proteins do all the work
5. Regents Biology
How do proteins do all the work
Proteins
proteins run living organisms
enzymes
control all chemical reactions in living
organisms
structure
all living organisms are built out of proteins
7. Regents Biology
Cell organization
Proteins
chains of amino acids
made by a “protein factory” in cytoplasm
protein factory = ribosome
nucleus
cytoplasm
ribosome
build
proteins
8. Regents Biology
Passing on DNA information
Need to get DNA gene information
from nucleus to cytoplasm
need a copy of DNA
messenger RNA
nucleus
cytoplasm
ribosome
mRNA
build
proteins
10. Regents Biology
DNA vs. RNA
DNA
deoxyribose sugar
nitrogen bases
G, C, A, T
T : A
C : G
double stranded
RNA
ribose sugar
nitrogen bases
G, C, A, U
U : A
C : G
single stranded
14. Regents Biology
Matching bases of DNA & RNA
Match RNA bases to DNA
bases on one of the DNA
strands
U
A G GGGGGT T A C A C T T T T TC C C CA A
U
U
U
U
U
G
G
A
A
A C C
RNA
polymerase
C
C
C
C
C
G
G
G
G
A
A
A
A
A
15. Regents Biology
Matching bases of DNA & RNA
U instead of T is matched to A
TACGCACATTTACGTACGCGGDNA
AUGCGUGUAAAUGCAUGCGCCmRNA
U C CCCCCA A U G U G A A A A AG G G GU U
ribosome
17. Regents Biology
How does mRNA code for proteins
mRNA leaves nucleus
mRNA goes to ribosomes in cytoplasm
Proteins built from instructions on mRNA
aa aa aa aa aa aa aa aa
How?
mRNA
U C CCCCCA A U G U G A A A A AG G G GU U
18. Regents Biology
How does mRNA code for proteins?
TACGCACATTTACGTACGCGGDNA
AUGCGUGUAAAUGCAUGCGCCmRNA
Met Arg Val Asn Ala Cys Alaprotein
?
How can you code for 20 amino acids with
only 4 DNA bases (A,U,G,C)?
ribosome
aa aa aa aa aa aa aa aa
19. Regents Biology
AUGCGUGUAAAUGCAUGCGCCmRNA
mRNA codes for proteins in triplets
TACGCACATTTACGTACGCGGDNA
AUGCGUGUAAAUGCAUGCGCCmRNA
Met Arg Val Asn Ala Cys Alaprotein
?
Codon = block of 3 mRNA bases
codon
ribosome
20. Regents Biology
For ALL life!
strongest support
for a common origin
for all life
Code has duplicates
several codons for
each amino acid
mutation insurance!
Start codon
AUG
methionine
Stop codons
UGA, UAA, UAG
The mRNA code
21. Regents Biology
How are the codons matched to
amino acids?
TACGCACATTTACGTACGCGGDNA
AUGCGUGUAAAUGCAUGCGCCmRNA
anti-codon
codon
tRNA
UAC
Met
GCA
Arg
CAU
Val
Anti-codon = block of 3 tRNA bases
amino
acid
22. Regents Biology
mRNA to protein = Translation
The working instructions → mRNA
The reader → ribosome
The transporter → transfer RNA (tRNA)
mRNA
U C CCCCCA A U G U G A A A A AG G G GU U
aa
aa
aa
tRNA
GGU
aa
tRNA
U A C
aa
tRNA
GA C
tRNA
aa
A GU
ribosome