DNA Structure
pg: 109
DNA
• Deoxyribonucleic Acid (DNA) –
holds ALL the instructions for making
proteins
• Nucleic Acid (DNA) is made up
of nucleotides.
Nucleotides are made up of:
1. Deoxyribose sugar
2. Phosphate
3. Nitrogenous base
Draw and label a nucleotide:
There are 4 different nitrogenous
bases:
• Adenine (A)
• Thymine (T)
• Guanine (G)
• Cytosine (C)
• Chargaff’s Rule – amount of
adenine is equal to the
amount of thymine & the
amount of guanine is equal to
the amount of cytosine
• The order of the nitrogenous
bases determines the kind of
protein made.
• ATE and EAT – same letters,
different meaning
Adenine
Purines
(2 rings)
Guanine
Thymine
Cytosine
Pyrimidines
(1 ring)
Who’s Who
• In the 1950s,
James Watson
and Francis
Crick were the
first to describe
the shape of
DNA
• Rosalind Franklin
should also receive
credit – without her
work, they would not
have been able to
finish
Shape
• DNA has 2 strands
• DNA is long so to
save space it twists
itself into a shape
called a double helix
• If you flatten DNA it looks like
a ladder. The sides of the
ladder are made up of
alternating phosphates and
sugars.
Review
• A bonds with T
• G bonds with C
• T bonds with A
• C bonds with G
Prymidines
Purines
• Adenine (A)
• Thymine (T)
Nitrogen bases
• Guanine (G)
• Cytosine (C)
Structure
Nitrogen Bases
Phosphate
Base
Sugar
Replication of DNA
• DNA Replication – copying DNA to
make identical copies
– one will be passed along to the new cells
during mitosis/meiosis
BONDS
Adenine = Thymine
Guanine = Cytosine
1)
2)
3)
4)
5)
6)
What is the full name for DNA?
What do we call the shape of DNA?
Who first discovered the shape of DNA?
What type of sugar is found in DNA?
What 2 substances make up the sides of DNA?
A phosphate, nitrogenous base, and a sugar
make a:
7) Where in the cell is DNA found?
8) DNA makes ________ for the body.
9) What are the nitrogenous bases in DNA?
10)What does adenine pair with?
DNA Replication
Pg: 44
Steps of Replication
1. An enzyme breaks the bonds holding the
two strands together
– That enzyme continues down the DNA
strand “unzipping” it
Steps of Replication
2. New nucleotides fly in and connect with
the open nucleotides
- Now there are 2
duplicate DNA
strands!
Reading DNA Replication
1.TGGCAATG
• ACCGTTAC
2.GTATGCCA
• CATACGGT
3.AATGCCGT
• TTACGGCA
4.CCCATGAC
• GGGTACTG
RNA Structures
pg: 53
DNA Replication Review
1.ATGGCT
• TACCGA
2.GCAGTT
• CGTCAA
3.TCGAGA
• AGCTCT
4.TTCCGA
• AAGGCT
RNA
• Ribonucleic acid
(RNA) – translates DNA
genetic code into the
actual proteins for the
cell
RNA
• Has single strand
• Ribose sugar
• NO Thymine, Uracil
instead
Comparison
DNA
• Double Strand
• Deoxyribose sugar
• Has thymine
RNA
• Single Strand
• Ribose sugar
• Has NO thymine,
uses Uracil instead
RNA Transcription
ex ATGGCT
• UACCGA
DNA
Transcription
1. GCAGTT
• CGUCAA
DNA
Transcription
2. AATGCC DNA
• UUACGG Transcription
3. TTGCAG
• AACGUC
DNA
Transcription
Protein is what the cell makes!
• Amino acid – building blocks of protein
3 types of RNA:
1. Messenger RNA (mRNA) – brings
instructions from the DNA
2. Transfer RNA (tRNA) – takes amino
acids to rRNA
3. Ribosomal RNA (rRNA) – puts amino
acids in the right order to make protein
Step 1
Step 1: Make RNA
• Transcription – enzymes use 1 strand
of DNA to make an RNA strand (instead
of Thymine, uses Uracil)
Step 2
Step 2: Translation – making protein
• Codon – 3 letters on the mRNA that code
for a protein
• Anticodon – a tRNA that matches the
codon, carries an amino acid
tRNA
 Amino Acid
tRNA
Codons
UUG – Leucine
AGU – Serine
ACA – Threonine
GGG - Glycine
UAU – Tyrosine
GUU – Valine
CUU –Leucine
GCA - Alanine
Quiz
1. What are the 4 bases of RNA?
2. What sugar does DNA have?
3. What sugar does RNA have?
4. Replicate this DNA: ATGG
5. What is the process of making RNA called?
6. Transcribe this DNA into RNA: AATG
7. What amino acid does CAA code for?
8. What does RNA help make for your body?
9. Define Codon:
10.Which RNA brings instructions from DNA?
Protein Synthesis
Pg. 65
Messenger RNA (mRNA)
carries instruction message from
the DNA
Amino Acid
basic building block of a protein
Transfer RNA (tRNA)
Translation
Codon
Ribosomal RNA (rRNA)
Anticodon
transfers amino acids to the
ribosomes
translates the information in the
mRNA into proteins
3 nitrogenous bases that form
amino acids
in the ribosomes, uses the
directions to put amino acids in
the right order
a tRNA that binds the 3 codons,
the opposite molecule from a
codon