DNA, RNA, and Proteins

1. Regents Biology
Learning Objectives
1. How is the code of DNA transcribed
into messenger RNA?
2. How is messenger RNA translated 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

6. Regents Biology
cytoplasm
nucleus
Cell organization
 DNA
 DNA is in the nucleus
 genes = instructions for making proteins
 want to keep it there = protected
 “locked in the vault”

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

9. Regents Biology
mRNA
From nucleus to cytoplasm
DNA
transcription
nucleus
cytoplasm
translation
trait
protein

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

11. Regents Biology
Transcription
 Making mRNA from DNA
 DNA strand is the
template (pattern)
 match bases
 U : A
 G : C
 Enzyme
 RNA polymerase

12. Regents Biology
Matching bases of DNA & RNA
 Double stranded DNA unzips
A G GGGGGT T A C A C T T T T TC C C CA A

13. Regents Biology
Matching bases of DNA & RNA
 Double stranded DNA unzips
A G GGGGGT T A C A C T T T T TC C C CA A

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

16. Regents Biology
protein
cytoplasm
nucleus
trait
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

23. Regents Biology
aa
aa
aa
aa
aa
aa
aa
mRNA
From gene to protein
DNA
transcription
nucleus cytoplasm
protein
translation
trait
U C CCCCCA A U G U G A A A A AG G G GU U
ribosome
tRNA
aa

24. Regents Biology
protein
transcription
cytoplasm
nucleus
translation
trait

25. Regents Biology
From gene to protein
transcriptiontranscription
translationtranslation
proteinprotein

26. Regents Biology
Cut to the video…
 http://www.youtube.com/watch?v=h3b9Arup

27. Regents Biology 2009-2010
Whoops!
See what happens when
your genes don’t work right!
Any Questions??