DNA & RNA
Unit 6Chapter 8 and 9
DNA HISTORY
Frederick Griffith (1928) Oswald Avery (1944)
Discovered that
bacteria could
transform from one
type to another. This
was known as the
Transforming Principle.
Discovered that DNA
is the nucleic acid that
stores and transmits the
genetic information
from one generation to
the next.
Alfred Hershey & Martha Chase
(1952)
They studied
viruses
Concluded that
the genetic
material in
bacteria was DNA
not proteins.
James Watson and Francis
Crick(1950’s)
created the
double helix
model for DNA.
Rosalind Franklin &
Maurice Wilkins
Worked with x-
ray
crystallography to
develop an x-ray
picture of DNA.
DNADeoxyribonucleic Acid
RNA
Ribonucleic Acid
Where does DNA “live”?
The NUCLEUS!
Why is DNA so Important?
* DNA is a nucleic acid that contains the genetic information used in the development and functioning of all living things and some viruses.
* DNA is like blueprints/instructions or a code for making proteins
* DNA’s codes are converted/changed into messages (mRNA) for ribosomes to read and then make proteins.
* Proteins do most of the hard work of
keeping us alive
WHAT ARE THE PARTS OF
DNA?
What are the parts of DNA?
*
D = Deoxyribose
(SUGAR)
P = Phosphate
The
“Backbone”
Has 2 Parts
2 Strands called:
Double Helix
What are the parts of DNA?
* The
“Rungs”
The Nitrogen Bases
A = Adenine
T = Thymine
C = Cytosine
G = Guanine
A - T
C - G
How to remember
Nitrogen Bonds:
A bonds with T
Think: A T & T
phone company
How to remember
Nitrogen Bonds:
C bonds with G
Think: Half circles
What are the parts of DNA?
* Nucleotides:
1 Deoxyribose
Sugar
1 Phosphate
group
1 Nitrogen Base
The 2 strands
are held together
by hydrogen
bonds
Anatomy of
DNANucleotide – consists of
a. Sugar
b. Phosphate
c. Nitrogenous base
1) adenine
2) cytosine
3) guanine
4) thymine
Anatomy
of DNA
Rungs of DNA molecule –
2 bases weakly held together
Adenine-thymine
guanine – cytosine
Anatomy
of DNA
• Side railings –
sugar bonded
to phosphate
Anatomy of
DNA
• Rungs bond
to side
railings by
base to
sugar
So, where within the eukaryotic cell is DNA located?•Eukaryotes have DNA within the
membrane bound nucleus•Prokaryotes have a circular DNA molecule but it is not protected by a nuclear membrane.•All living things on Earth have DNA molecules with the same structure and function. •And all living things on Earth share some of the same DNA sequences.
These are 2 examples of
nucleic acids:
A. Chloroplasts & Mitochondria
B. Carbohydrates & Lipids
C. DNA & RNA
D. Nucleus & Ribosomes
. Question #1
DNA holds the
instructions for making:
A. Energy
B. Proteins
C. Carbon dioxide
D. Deoxyribose
. Question #2
If 20% of a DNA’s strand
contains Thymine, then:
A. it also has 80% Guanine
B. it also has 50% Cytosine
C. it also has 80% Adenine
D. it also has 20% Adenine
. Question #3
What type of sugar is
found in DNA?
A. Phosphorous
B. Thymine
C. Ribose
D. Deoxyribose
. Question #4
The DNA’s code is converted into
_____ so it can be sent to
ribosomes to make the proteins.
A. DNA
B. mRNA
C. tRNA
D. ATP
. Question #5
Lets Practice:
What are the complementary nitrogen
bases in this sequence of DNA?
ATT CGT TAT CGT CTG AAA ACG
TAA GCA ATA GCA GAC TTT TGC
What did we
just do?
Yes!
We made
DNA!
The Central Dogma
Francis Crick defined “Central Dogma”
which states that information flows in one
direction from DNA to RNA to Proteins.
Importance of DNA
All living things contain DNA made of the same
4 nitrogen bases
–This is strong evidence of evolution and
common ancestry
•However… the order of the bases is different
in every species and every individual.
–NO ONE has the same order of bases as you!
•The order of the nitrogen bases is what makes
an organism unique.
DNA Replication
DNA must be copied before cell
division
(Mitosis or Meiosis)
•Replication – the process of copying
DNA
–Each old DNA strand will serve as a
pattern to make a new DNA molecule
Steps of DNA Replication
1.Enzymes break the hydrogen bonds between base
pairs at the “Origin of Replication.”
•A stretch of DNA with a specific sequence that
singles the start of replication.
•(Unzipping the DNA molecule)
2.Free nucleotides in the nucleus bond to the
unzipped single strand of DNA by base-pairing (A/T
and G/C)
3.Another enzyme bonds these nucleotides into a
chain.
• The process continues until the entire
molecule is unzipped and copied
• New daughter strands formed are
identical to each other and the parent
strand.
Enzymes involved in DNA Replication
•Enzymes are involved in every step of replication
1.Helicase
–Untwists the double helix and separates the two parent DNA
strands.
2.DNA Polymerase
–Adds nucleotides to the open parent strand of DNA and makes
covalent bonds between the nucleotides of the new DNA
strand.
3.DNA ligase
–Joins DNA fragments into a single DNA strand
Process is amazingly fast and accurate
–Proceeds at a rate of 50 nucleotides per
second with only about one in a billion
incorrectly paired.
•Process ensures that ALL body cells in a
multicellular organism carry the same genetic
information.
•Also the means by which genetic information
is passed along to offspring.
Function of DNA
DNA is a code – The Genetic Code
•The order of the nitrogen bases or nucleotides
determines the message
•Changing the order of the bases will change the
message
•Each message gives the cell instructions for making
proteins.
•Proteins give an organism all its traits
•The Genetic code is a code for making proteins!
Proteins
Complex polymers made of sub-
units called amino acids.
•Proteins determine the
structure and function of an
organism
•The sequence of bases codes
for a protein.
•3 Nitrogen Bases = 1 Amino
Acid
•Codon – set of 3 nitrogen bases
representing an amino acid.
Codons
4 nitrogen bases -64 different possible
combinations
•64 different codons in the genetic code!
–61 code for amino acids
–3 signal to STOP protein synthesis
•However… there are only 20 amino acids… so
some of the codons will code for the same
amino acid
How to make a Protein… 2 Parts:
1. Transcription – DNA to RNA
2. Translation
– RNA to protein
RNA
What are the parts of RNA?
* Just Like DNA, RNA has:
Sugar
Phosphate
Nitrogen Base
BUT…..
RNA is Made of:
Ribose (SUGAR)
Phosphate (same as DNA)
Nitrogen Bases (A,U, C, G)
First:
Notice that RNA has 1 Strand!NO THYMINE in RNA!!U stands for Uracil….
a different nitrogen base
RNA Nitrogen Bases:
A bonds with U
C bonds with G
THYMINE in RNA!!
What is the function of
RNA?
RNA carries the messages
from the DNA (in the nucleus)
to the ribosomes (in the
cytoplasm).
RNA tells the ribosomes
which proteins to make and
how to make them.
RNA & DNA Differences
RNA is a single strand, DNA is a
double strand.
The sugar in RNA is ribose
(C5H10O4)the sugar in DNA is
deoxyribose (C5H10O5)
RNA has uracil that pairs with
adenine, DNA has thymine that
pairs with adenine.
How does DNA tell the cell to make
a specific kind of protein?
* First: Transcription
* Second: Translation
* There are 2 major steps in this process
How is RNA made? • Transcription converts
DNA into RNA.
• This is done through RNA Polymerase.
Note: DNA Polymerase
builds DNA, RNA
Polymerase builds RNA
• RNA Polymerase unzips DNA and makes a complimentary mRNA strand.
Transcription
•Process where enzymes make an RNA copy of DNA
•Similar to DNA replication but results in a single strand of RNA
•DNA message must be carried from the nucleus to the ribosomes
•RNA carries the message.
RNA vs DNA
There are 3 types of RNA
• Messenger RNA (mRNA) – is a recipe to make a protein. Carries the DNA message to the ribosomes (conds)
• Transfer RNA (tRNA) – brings amino acids from the cytoplasm to a ribosome to help make the growing protein. Carries anti codons that match the mRNA codons
• Ribosomal RNA (rRNA) – makes up a ribosome, a cell’s protein factories. Makes enzymes that bond amino acids together
Why is mRNA Important?
* mRNA is created by DNA in the nucleus
* mRNA contains the messages from the DNA and are sent to ribosomes for them to read the instructions for making proteins
* DNA is too big and CAN’T leave the nucleus…it must send messages
What 3 things make up a
nucleotide?
A. Nucleus, DNA, & RNA
B. Adenine, Thymine, & Cytosine
C. Sugar, Phosphate, & a Nitrogen base
D. Chromosomes, Genes, & DNA
. Question #6
Where is mRNA made?
A. In the nucleus
B. In the cytoplasm
C. In the mitochondria
D. In the ribosomes
. Question #7
What type of sugar does
RNA have?
A. Deoxyribose
B. Carbohydrate
C. Ribonucleic acid
D. Ribose
. Question #8
Which of the following
nitrogen bases does RNA
not have?
A. Uracil
B. Thymine
C. Adenine
D. Cytosine
. Question #9
If a strand of DNA
contains 40% of Cytosine,
then
A. it also contains 40% Guanine
B. it also contains 60% Thymine
C. it also contains 40% Cytosine
D. it also contains 60% Guanine
. Question #10
How does DNA tell the cell to make
a specific kind of protein?
Transcription : Process in which mRNA is
synthesized from the DNA template.
* mRNA: (messenger RNA) holds the
recipe for making proteins
*** Transcription is when mRNA is made from DNA.***
HINT:
Steps of Transcription
1.Initiation –RNA polymerase (an enzyme) pries apart the DNA and
attaches to the DNA at the beginning of the gene to be
transcribed.
2.Elongation –RNA nucleotides align with the open DNA strand…
base pairing A with U and C with G.
–RNA nucleotides are linked together by RNA
polymerase into a single chain.
3.Termination –When a stop codon is reached RNA polymerase
detaches from the gene and the DNA rejoins.
Lets Practice:
Create a RNA strand using this
sequence of DNA?
ATT CGT TAT CGT CTG AAA ACG
UAA GCA AUA GCA GAC UUU UGC
We just
transcribed
DNA into
mRNA!
This is
mRNA!
What does mRNA do?
A. It carries the instructions from DNA to ribosomes to make proteins
B. It carries instructions from the ribosomes to the nucleus to make DNA
C. It carries the instructions from the nucleus to the mitochondria to make energy
D. It carries instructions from the nucleus to the cytoplasm to make energy
. Question #11
What is transcription?
A. The process of making energy
B. The process of making proteins
C. The process of making DNA
D. The process of making mRNA
. Question #12
Lets Practice This Again:
Create a RNA strand using this
sequence of DNA?
ACA CGA TTA CGG ATA CGC ATC
UGU GCU AAU GCC UAU GCG UAG
What did
we just do?
YES!
We transcribed/made
mRNA from DNA
Now what?
Now What?...Translation!
Translation: Process in which mRNA attaches
to the ribosome and a protein is assembled/made.
* Codon: 3 base code in DNA or RNA
Words to know:
* Amino Acid: Compounds joined by peptide bonds
to build proteins
* Ribosome: “Reads” mRNA recipes so it can
synthesize/make proteins
ACG ATA CGG CTTThere are 20 different Amino Acids.
Different combination of Amino Acids make
different kinds of proteins.
Now What?...Translation!
* tRNA: (transfer RNA) Type of RNA that
transports amino acids to the ribosome
More Words to know:
* Anticodon: Nitrogen bases that can pair that
corresponds with the codons on the mRNA
tRNAAmino
Acid
Anticodon
What happens during
translation?
Ribosome
Peptide chain/
Protein Chain tRNA
Amino
AcidAnticodon
Codon
Translation
1. Initiation – mRNA travels from the nucleus and attaches to the
ribosome in the cytoplasm at the start Codon AUG.
2. Elongation – A tRNA carrying an amino acid attaches its anti-codon
to the 1st mRNA codon.
– A second tRNA comes in next to the first and attaches
its anti-codon to the 2nd mRNA codon • The two amino acids are now lined up next to each other.
– An enzyme joins them by forming a peptide bond
between the amino acids
Translation Video...
Where does translation
occur?
A. In the nucleus
B. In the mitochondria
C. In the DNA
D. In the ribosome
. Question #13
What is made during
translation?
A. DNA
B. mRNA
C. Protein
D. Energy
. Question #14
What is another name
for polypeptide chain?
A. Protein chain
B. Carbohydrate chain
C. Lipid chain
D. Nucleic acid
. Question #15
#1. AUG GCA UCC UGA
Methionine, Alanine, Serine, Stop
#2. AUG CCC GGU UAG
Methionine, Proline, Glycine, Stop
#3. AUG AAG GUG UGA
Methionine, Lysine, Valine, Stop
Translating mRNA codes into amino
acids to create polypeptid chains
(protein chains)
What is the amino acid for the
following codons?
AAUAsparagine
(Asn)
GUGValine
(Val)
UGGTryptophan
(Trp)
How can knowing amino acid
sequences in organisms help
biologists?
We can use the sequences to see how organisms are related!
Fish Sequence: Methionine, Isoleucine, Arginine, Isoleucine, Glycine, Serine
Frog Sequence: Methionine, Isoleucine, Serine, Leuicine, Lysine, Lysine
Bird Sequence: Methionine, Isoleucine, Serine, Glycine, Alanine, Valine
Lizard Sequence: Methionine, Isoleucine, Serine, Glycine, Alanine, Tyrosine
Which of the following two organisms
are MOST closely related?
The end…For now…
DNA Mutations
& Technology
What are genetic mutations?
Mutation: Permanent change in a cell’s DNA,
ranging from changes in a single base pair to
deletions of large sections of chromosomes.
Causes of mutations are mutagens
include:
* Viruses
* Radiation
* Chemicals
* Errors during mitosis and meiosis
Are mutations harmful?
Some mutations are harmful, some are
beneficial, and some do nothing.
Harmful example:
- Some mutations cause cancer & genetic disorders
Are mutations harmful?
Helpful example:
- Sickle cell anemia prevents malaria
Are mutations harmful?
Not harmful or helpful:
- Peppered moths come in dark or light colors
• Here there is a change in one or more of the nucleotides in a strand of DNA
1. POINT MUTATIONS
Substitution Mutations
2. FRAMESHIFT MUTATIONS
Insertion Mutations
Deletion Mutations
76
Types of Mutations
Point or Substitution Mutation
• One base (A, T, C, or G) is substituted for another
• Causes: Sickle-cell anemia
• 3 Possible Consequences:
– nonsense mutations: changes the amino acid to a “stop codon” ex: UGA, UAA, UAG
– missense mutations: changes the amino acid
– silent mutations: does not change the amino acid
What are some types of mutations?
There are many different types…we will do an activity that
demonstrates these mutations:
1. Insertion
What are some types of mutations?
2. Deletion
What are some types of mutations?
3. Translocation
What are some types of mutations?
4. Duplication
How has technology changed DNA?
Genetic Engineering: Technology used to manipulate an
organism’s DNA by inserting the DNA of another
organism.
Transgenic Organism: Organism that is genetically
engineered by inserting a gene from another organism.
How has technology changed DNA?
Gel Electrophoresis: Process that involves using electric
current to separate certain biological molecules by size.
We use this to see DNA fragments to create a DNA fingerprint
- DNA fingerprints have 2 major uses:
1.Solve crimes
2.Figuring out “who’s father”
DNA Fingerprinting
Which of the following are his/her parents?
Who did it?
What is the human genome?
Genome: Total DNA in each cell nucleus of an organism
The Human Genome Project:
* Began in 1990 and completed in 2003
* Found that we have 3 BILLION chemical base pairs
* Used to understand genetic disorders and to them
What is cloning?
Cloning: Process in which large numbers of identical
recombinant DNA molecules are produced.
“Dolly” the sheep was the first cloned animal