Download DNA Bases

Chapters 9 - 11
DNA
Protein Synthesis
& Gene Technology
DNA
• DNA- deoxyribo nucleic acid
– DNA is a genetic molecule that contains all of
the instructions to create an organism
• Structure of DNA:
– Double helix “spiral ladder”
– Discovered by James Watson
Francis Crick
&
Nucleotides
• Nucleotides are the basic subunits that
make up DNA
• Nucleotides consist of 3 molecules: a
phosphate, a sugar, and a base
Diagram:
5-carbon
Sugar
DNA Bases
• There are 4 different DNA Bases:
A: Adenine
T: Thymine
C: Cytosine
G: Guanine
DNA Base Pairs
• DNA bases always pair in the same way
A:T
C:G
- adenine pairs with thymine
- cytosine pairs with guanine
DNA Strand:
A
T
G
C
G
A
- fill in the corresponding DNA bases
Remember:
A:T
C:G
T
C
A
DNA Replication
• DNA replication is the process of copying
DNA
• It occurs during S-phase of the cell cycle
• Makes 2 exact copies of a cells DNA
Steps in DNA Replication
1) The two original DNA strands separate
- the DNA-helicase enzyme separates
the two DNA strands
Diagram:
Steps in DNA Replication
2) DNA-polymerase enzyme forms two new
DNA strands to match the original strand
Diagram:
Steps in DNA Replication
3) Two DNA molecules are formed that are
identical to the original DNA molecule
Diagram:
DNA Mutations
• Any change in the genetic code of an
organism is a mutation
• Mutations may have a small, large, or no
effect on an organism
Mutagens:
- substances that can cause mutations
Ex: toxic chemicals, UV radiation,
nuclear radiation, extreme heat
RNA
• RNA – ribo nucleic acid
3 Types of RNA:
rRNA - ribosomal RNA
- used to make ribosomes
tRNA - transfer RNA
- used to make proteins
mRNA - messenger RNA
- used to send messages from
the nucleus to the cytoplasm
RNA Bases
• RNA uses Uracil(U) instead of Thymine(T)
RNA Base Pairs:
A:U
C:G
AGU CAU GUG CAC UUA CAG AUC GCA
Transcription
• Transcription is used to make mRNA
Steps:
1) RNA-polymerase enzyme binds to DNA
2) The two DNA strands unwind & separate
3) mRNA is made by RNA-polymerase
based on the genetic code of the DNA
Reading the Genetic Code
Codons: a series of 3 nucleotides that code
for an amino-acid
- each codon is used to create an aminoacid
RNA Codons
Codon
A
U
G
C
C
A
C
A
U
U
G
A
Translation
• Translation forms proteins from RNA
Steps:
1) Ribosomes bind to mRNA in cytoplasm
2) tRNA carrying amino-acids attaches to the
mRNA
3) Amino-acids from the tRNA begin to form a
chain(polypeptide)
4) When the ribosome reaches the end of the
mRNA it detaches
5) The polypeptide chain is complete, forming a
protein
Translation
Amino-Acids
Ribosome
tRNA
mRNA
Overview of Protein Synthesis
DNA
mRNA
Transcription
Protein
Translation
Genetic Engineering
• Genetic engineering is used to create
organisms with specially designed genes
& traits
Recombinant DNA- pieces of DNA
combined from 2 different organisms
Gene Splicing
Uses of Recombinant DNA
• Insulin- make bacteria produce insulin for
human use to treat diabetes
• Resistance- can put recombinant DNA
into plants to make them resist
diseases
• Vaccines- can use recombinant DNA in
animals to produce immunity to
diseases
Cloning
• Cloning is the production of organisms
with identical genes
END OF CHAPTER 9-11 NOTES!!!