Download The nitrogenous bases

DNA to PROTEIN
CHAPTER 12
 DEOXYRIBONUCLEIC ACID
DNA: replication and protein
synthesis
Where have we seen DNA being
replicated?
MITOSIS
AND
MEIOSIS
Building blocks of DNA: Nucleotides
The sugar
Deoxyribose
The phosphate
The nitrogenous bases
The Purines
Why are these called nitrogenous bases?
The nitrogenous bases
The Pyrimidines
How are the pyrimidines different from the
purines?
Four different Nucleotides
BASIC
STRUCTURE
DNA is a polymer formed by base
pairing: Base pairing rule
The Double Helix
A. The overall shape of DNA is described as a double
helix (a twisted ladder).
B. What force holds the two strands together?
How are DNA and RNA similar?
 DNA is composed of nucleotides and RNA is
composed of nucleotides
How are DNA and RNA different?
How are DNA and RNA different?
 DNA…
 Nucleotides = deoxyribose sugar
 Double helix structure
 Stays inside nucleus
 RNA…
 Nuleotides = ribose sugar
 Single-strand structure
 Located both inside and outside of nucleus
 Uracil instead of thymine
Enzymes involved in DNA replication
 Helicase – opens the double helix to allow for
replication
 DNA polymerase – reads the original DNA
strand and lays down complementary bases
 Ligase – glues the newly formed DNA
together
DNA replication practice
 You are DNA polymerase. Helicase has opened the
DNA strand – read each side and produce the
complementary copies.
__________________________________
AGGTAACCGGTTACGATTAT
TCCATTGGCCAATGCTAATA
AGGTAACCGGTTACGATTAT
TCCATTGGCCAATGCTAATA
Do # 9 IN YOUR NOTES TO
PRACTICE BASE PAIRING RULES
AGAIN
__________________________________
A G T C C G T T A G T
T C A G G C A A T C A
Protein Synthesis= transcription and
translation
 DNA contains all the information for your
traits – the genes
 These genes are blueprints and need to
remain safe – kept inside the nucleus
 Copies can be made though – a messenger
Genotype  Phenotype
DNA mRNA tRNA PROTEIN
Transcription
Translation
Transcription
 mRNA – stands for messenger RNA



it is the copy of the DNA message for making
a protein
Occurs in the nucleus
Promoter region on DNA marks where
transription should start and terminator region
marks where it should stop
mRNA
 Transcribes DNA message and carries it to
ribosome
 RNA polymerse is the enzyme that produces
it (#8 in notes)
CLICK ON
PICTURE FOR
ANIMATION ON
TRANSCRIPTION
mRNA
 No T (thymine) so when it reads the
nucleotide A on DNA it matches it with ____?
tRNA
 Once mRNA is made it attaches to a
ribosome
 tRNA = transfer RNA and they carry amino
acids
 Amino acids are the building blocks of
proteins (remember?)
Translation
 Ribosomes are the site of protein synthesis
Codon = mRNA
Anti-codon = tRNA
Let’s Review
 DNA Structure is a _____ ______
 DNA is composed of __________
What are four that make up DNA?




A
T
C
G
Concept Map
Section 12-3
RNA
can be
Messenger RNA
also called
Ribosomal RNA
which functions to
mRNA
Carry instructions
also called
which functions to
rRNA
Combine
with proteins
from
to
to make up
DNA
Ribosome
Ribosomes
Transfer RNA
also called
which functions to
tRNA
Bring
amino acids to
ribosome