1. NOTES;
DNA

2. A T G C 2 3 E HYDROGEN PURINES PYRIMIDINES = FIT TOGETHER,
LIKE PUZZLE PIECES A T 2
HYDROGEN G C 3
THYMINE
CYTOSINE
PURINES
PYRIMIDINES

3. D T
SUGAR C T T G N G A A G
PHOSPHATE C C A

4. As the bases “stack”, they spiral forming a “helix” and since DNA
is made of 2 strands it’s a…
DOUBLE
HELIX

5. (the first step in mitosis
When the time comes
For dna to copy itself
(the first step in mitosis
And meiosis), the helix
Must be “unzipped”
You need an…
NZYME!!!
(HELICASE)
Hmmm…you need to “break a BIG molecule into 2 smaller pieces”…

6. An EXACT copy of the original …for the next generation!!
TEMPLATE A A T A C G G T T
COMPLEMENTARY
An EXACT copy of the original
(double) strand…
…for the next generation!!

7. The process of COPYING DNA
REPLI
The process of COPYING DNA
COPY #1
ORIGINAL
STRAND
COPY #2

8. DNA is replicating less than 1% of a cell’s “life cycle”…so what
is DNA doing the other 99%?
FIRST, THE DNA IS UNZIPPED

9. A A T A C G G T T Most of the time the template
DNA is read by a DIFFERENT
kind of Nucleic Acid…one that
has a backbone made of RIBOSE

10. A And there are other differences R N A U The sugar is RIBOSE
RNA is SINGLE stranded
RNA contains URACIL
instead of Thymine
And being single-stranded,
THYMINE won’t “fit”!!
So it is replaced by another
pyrimidine called… R
A “base” that is very similar
to Thymine, also forming
2 Hydrogen bonds, making
it COMPLEMENTARY to… N A
Finally, unlike DNA, there are
different kinds of RNA A U

11. The first kind of RNA “reads” This RNA “copy” must now
the DNA…it is called…
This RNA “copy” must now
leave the nucleus…
RNA
RNA
essenger U U A U G C C A A
THIS PROCESS IS CALLED
COMPLEMENTARY BASE PAIRING!!
CRIPTION A A T A C G G T T
RNA
LEAVES
NUCLEUS
THE PROCESS OF MAKING AN RNA COPY OF THE DNA

12. REMEMBER!
REPLI
DON’T
CONFUSE
with
CRIPTION

13. THAT UP THERE HAS ABSOLUTELY NOTHING TO DO WITH THIS REPLI
COPYING DNA so new cells
have a set of instructions
HAS ABSOLUTELY
NOTHING TO DO
WITH THIS
THAT UP
THERE
CRIPTION
CRIPTION
The first step in making proteins

14. THIS
involves both DNA
AND RNA
involves NOTHING
but DNA

15. THIS is what cells do 1% of the time is DNA copying itself
DNA can REPLICATE
So don’t mess up
Major Concept #2
is what cells
do 1% of the
time
is DNA
copying
itself
is the first
step needed
to build stuff
is what cells
do 99% of the
time
In fact, the only thing
they have in common is

16. Once Transcription is complete, the mRNA leaves the nucleus
CYA L8r G8r!!
DNA

17. so it is called mRNA rRNA Where it enters a RIBOSOME
A structure made entirely
out of
…RNA…
ribosomal RNA, to be exact
mRNA
rRNA
so it is called

18. Biologists wondered… is the code “read” just ONE base at a time?
Or two?
Or…
They knew they needed a code that was able to have
AT LEAST 20
varieties (to account for the 20 different amino acids)

19. But what about the other 16?
A 1-base code wouldn’t A T G C
Would code for, say… ALAnine
Would code for, oh, I don’t know… LEU cine?
Would code for, maybe… ISOleucine
and would code for, say… TRYptophan
But what about the other 16?

20. What about a 2-base code? Still…not enough combinations
AA CA GA UA
AC CC GC UC
AG CG GG UG
AU CU GU UU
These are all the possible combinations of just two bases
Still…not enough
combinations
for all 20-something
amino acids.

21. And the UGC was created;
With 3 bases you get
64 combinations…more
than enough!
And the UGC was created;
A 3-base code is enough
to include all 20 AAs

22. And so this 3-base
set became known as a
CODON

23. amino acids are “delivered” to the ribosome by a third
kind of RNA:
Just remember, the
Universal Genetic
Code (UGC)
is based on
CODONS
(the mRNA)
NOT anticodons
called transfer RNA or
tRNA
And the complement to a
CODON is an
ANTICODON

24. So exactly what happens
inside the ribosome?
One language* gets
turned into another
AMINO A A A U U G U U C
*the language of Nucleic Acid is converted into the language of…

25. U U U LYS The codon AAA is next-in-line. The tRNA that “fits” is… UUU
Remember!! The UGC reads CODONS!!!!!
UUU
LYS
As you can see, each tRNA
has a “personal payload”, a
unique “cargo” that it brings
to the ribosome…an amino
acid U U U
So the codon AAA called for the tRNA anticodon UUU carrying LYSINE
Which amino acid?? That’s where the UGC is needed

26. One more time… DNA codes for RNA which dictates the
(1) The DNA sequence TTT is read by the mRNA
DNA codes for
RNA which dictates the
AMINO ACID sequence
which is what “stuff”
is made of!
(2) The mRNA “codon” of AAA then leaves the nucleus
(3) The mRNA is grabbed by the first available ribosome
(4) As the codon AAA is drawn into position, a tRNA with the anticodon
UUU momentarily binds to its complement, bringing with it the
amino acid LYSINE
(5) The LYSINE then forms a (peptide) bond with the other amino acids
already in the chain
(6) Eventually the amino acid chain is released by the ribosome,
now a fully-functional PROTEIN

27. Let’s finish the notes…
ribosome
ALA
peptide
PHE
C G A
LYS
AMINO
A A A
ANTICODON
Let’s finish the notes…
U U U
tRNA
mRNA
CODON
rRNA
Followed by GCU
The next codon in the sequence is UUU
Using the UGC, determine the AAs

28. or what we like to call a…
PROTEIN
ALA
MET
TRY
or an ENZYME or HORMONE
aka
STUFF!!!!!!!!!!!!!!!!
This final step of converting DNA into Protein, where nucleic acids dictate the order of amino acids, is called…
As MET-TRY-VAL-LYS-PHE-ARG emerge from the ribosome, their UNIQUE sequence forces the chain to BEND/FOLD, giving THIS CHAIN its UNIQUE properties
or what we like to call a…
C A ?
G U ?
UGG
The AA valine (VAL)
preceded LYS because of the codon (and anticodon)
Now try it “backwards”
Let’s do a couple more
The ? is due to the fact that there are 64 codons for 20 AAs
LATION
Converting the language of NAs
into the language of AAs

29. INSIDE THE How are these NUCLEUS related within the cell? MC #2 MC #1
REPLI
MC #1 D N A
MC #3
PROTEINS R N A
TESTOSTERONE
AMYLASE
KERATIN
INSULIN or
CHLOROPHYLL!
MC #4
CHAINS of AAs