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