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The Twisting Tale of DNA: Ted ED

DNA Vocabulary

quizzesQuiz #11. Nucleotide2. Base Pairing3. Transformation4. Deoxyribose5. Double Helix6. Chromatin7. Replication8. DNA

Polymerase9. Helicase10. Chromosome11. Complementary12. DNA

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UNIT GOALS– Distinguish between DNA and RNA.– Explain the role of DNA in storing and

transmitting cellular information.– Describe the relationships between

changes in DNA and potential appearance of new traits including – alterations during replication, insertions, deletions, substitutions, mutagenic factors, radiation, chemicals.

– Examine the use of DNA technology in forensics, medicine and agriculture.

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DNADNA• Function:Function:

Store & Transmit genetic information

• Acts as a library or storehouse of informtion.

• DNA is locatedlocated in the nucleus.

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Discovery of DNADiscovery of DNA

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Many People contributed to the discovery of DNA.

Frederick GriffithFrederick Griffith (Transformation)

Experiments with Diplococcus pneumonia (bacterium responsible for

pneumonia), witnessed a transformation.

•These experiments are recognized as the first in a series that lead to the conclusion that DNA is the DNA is the carrier of genetic carrier of genetic informationinformation, the genetic material.

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DNA is the molecule of inheritance

Oswald Avery• Repeated Griffith’s

experiment• Looking for “what” is

being transferred.• Used enzymes to break up

carbohydrates, lipids and proteins-transformation still took place.

• Used enzymes to break up DNA-transformation did not happen.

• Conclusion: DNA is a Nucleic Acid

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Rosalind Franklin & Maurice Wilkins

•Used x-ray diffraction to see DNA.

•Conclusions: DNA is twisted like a spiral staircase

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Double helix

Erwin Chargaff• Discovered that the

– amount of Adenine = amount Thymine

– amount of cytosine = amount of guanine.

• True in all organisms tested.• Called Chargaff’s Rule.

•Conclusions:Conclusions:

1. amt A is = to amt of T 2. amt C is = to amt of G

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Watson and Crick“Put it all

together” Developed the

structure of DNA that we know today.

Conclusions:Conclusions: Described the complete structure of DNA.

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Structure of DNAStructure of DNA1. Double Helix.

-Twisted ladder or spiral staircase

2. Two stranded3. Held together

by hydrogen bonds

4. Made of four Nucleotides

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1. Phosphate2. Base ( Nitrogen)3. Sugar

RememberRemember: :

• DNA is a nucleic acid.

• Nucleic acids are made of nucleotides

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Structure of DNAStructure of DNA

Nucleotides• Long chain of

Nucleotides• There are four

nucleotide that make up DNA

• Each nucleotide Each nucleotide has three parts:has three parts: 1-Sugar, 2-Phosphate, 3-Base) • The sugar is Deoxyribose• There are four bases

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Structure of DNAStructure of DNA

4 Bases• Adenine• Guanine• Cytosine• Thymine

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Sides of the Sides of the “Ladder” are “Ladder” are made up of made up of sugar and sugar and

phosphate.phosphate.

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AdenineAdenine always pairs with always pairs with ThymineThymine

CytosineCytosine always pairs with always pairs with GuanineGuanine

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Would Thymine be able to pair up with Guanine?NO!!

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The sequence of nucleotides forms the

unique genetic information of an organism.

FlashbackBefore a cell

divides it needs to make a copy

of its DNA.(Remember S-

phase?)

How does it do that?

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DNA has the unique ability to make an exact copy of itself in a process called

Replication.

Chromosome Structure

• DNA is packed very tightly in the nucleus.

• Human nucleus has ~1 meter 1 meter of DNA!of DNA!

• Smallest human chromosome has 30 million base pairs.

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• A chromosome has DNA and protein-chromatin.

• Tiny sections of DNA are called genes

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DNA DNA ReplicationReplication•Before Cell

Division, the DNA must be replicated exactly.

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DNA DNA ReplicationReplication

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Each strand is used to make a new strand.

•Many enzymes are involved.

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Complementary Strands

Steps:1. The two

parent strands are unwound and unzipped with the help of DNA helicases.

Replication Bubble

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Steps:2. DNA

polymerase attaches new nucleotides (base

paring) to the parent strands

**Each new strand formed is a complement of one of the original, or parent, strands.

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• This process will continue until the entire molecule has been unzipped and replicated.

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DNA replication website 3131

The replication of DNA is called

Semi-conservative replication

Each new strand formed is a complement of one

of the original, or parent strands.

When all of the DNA in the chromosomes of the cell have been copied by replication, there are now two copies of the genetic information that will be passed on to new cells during mitosis or to new generations through the process of meiosis.

3232Review Clip

DNA Vocabulary

quiz

Quiz#21. Messenger RNA2. Transfer RNA3. Transcription4. Translation5. Codon6. Anti-Codon7. Promoter8. Intron9. Exon10.Genetic Code11.Amino Acid12.Protein13.Polypeptide14.Mutation15.DNA16.RNA

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•How does the ribosome get the information?

•How does the ribosome read the information?

•How does it make the protein?

DNA stores the information needed by a ribosome to make a

protein.

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UNIT GOALS– Distinguish between DNA and RNA.– Explain the role of DNA in storing and

transmitting cellular information.– Describe the relationships between

changes in DNA and potential appearance of new traits including – alterations during replication, insertions, deletions, substitutions, mutagenic factors, radiation, chemicals.

– Examine the use of DNA technology in forensics, medicine and agriculture.

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EQ: How does a protein get made?EQ: How does a protein get made?

““PROTEIN SYNTHESIS”PROTEIN SYNTHESIS”

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DNA contains the code DNA contains the code for all of the cell for all of the cell

proteins.proteins.

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Flashback:• DNA is located in the Nucleus• Proteins are made on the ribosomes.• DNA makes a copy (send a message)

called “mRNA”

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Two Steps of Protein Synthesis1. Transcription 2. Translation

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LOCATIONS

Where do the steps take place?

1. Transcription: Nucleus

• During transcription a “backwards copy” of the DNA is made…the copy is called messenger RNA or mRNA.

• The mRNA takes the code to the ribosome.

• During transcription the DNA unwinds and RNA nucleotides are paired up with DNA bases.

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Animation

DNA vs. RNA• Double

Stranded

• AGTC

• Deoxyribose

• NEVER!

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• Single Stranded

• AGUC

• Ribose

• YES!

1. Transcription: Nucleus

• The section that is copied is called a gene.

• The gene contains the code for a protein.

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“backwards copy”

During transcription the

DNA opens up and RNA nucleotides

are paired up with the DNA bases.

• Once the mRNA copy is made, it can go to the ribosome and be used to make a protein (translated)

2. Translation: Cytoplasm 4141

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• To have the correct translation of the code, mRNA codons must join with the correct anticodon

of the tRNA.

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mRNA codons

tRNA anticodon

Ribosome

2. Translation: Cytoplasm

The ribosome reads every 3

letters

• To have the correct translation of the code, mRNA codons must join with the correct anticodon of the tRNA.

mRNA codons

tRNA anticodon

A codon is a group of 3 nitrogenous bases on an mRNA molecule that carries the code for a specific amino acid. An anticodon is a set of 3 nitrogenous bases on a tRNA molecule that matches a codon on an mRNA molecule.

2. Translation: Cytoplasm

animation

tRNA brings the amino acids to the ribosomes

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• Remember….Proteins are made out of amino acids.

• There are 20 different amino acids.

• 3 bases code for each amino acid.

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mRNA codons

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The Genetic Code

Another version of the Genetic Code

Review Clip

In summary:•Messenger RNA (mRNA) carries the message of the genetic code from the DNA in the nucleus to the ribosomes in the cytoplasm. •At the ribosomes, the mRNA sequence is translated into a protein in a process known as translation. Transfer RNA (tRNA) transfers the amino acids in the cytoplasm to the ribosomes.

•The amino acids are lined up in the coded sequence to form a specific protein.

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Review link (in Spanish, but GREAT animation)

Animation “in real time”

“Stated Clearly” Review of Protein Synthesis

Exon - RNA sequences in the primary transcript that are found in the mRNA

Intron - RNA sequences between exons that are removed by splicing

Eukaryotic DNA processingSometimes the DNA is cut up before it leaves the nucleus.

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EOCT QuestionsWhich of the following shows how information is transformed to make a protein?

A DNA→RNA→proteinB gene→chromosome→proteinC cell respiration→ATP→proteinD ATP→amino acid→protein

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Information on mRNA is used to make a sequence of amino acids into a protein by which of the following processes?

A replicationB translationC transcriptionD transference

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A characteristic of RNA is that it

A remains in the chromosomes in the nucleus

B is involved in translating information in DNA into proteins

C undergoes crossing-over during meiosis

D is replicated during the process of mitosis

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Which of the Which of the following is the following is the

correct base-pairing correct base-pairing rule for DNA?rule for DNA?

A A-U; C-GB A-G; T-CC A-T; G-CD A-C; T-G 5252

Mutations

Describe the relationships between changes in DNA and appearance of

new traits

5353Mutations: Youtube

Mutations•Every so often genes do change.•A sudden change in the genetic

code is called a mutation.•Most mutations have little or no effect on the organism.

•Mutations can be spontaneous or may be caused by environmental factors called mutagens.

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Mutations in DNA usually occur through one of two processes:

1- DNA damage from environmental agents such as :

• UV lightUV light• RadiationRadiation• Free radicalsFree radicals• Chemicals Chemicals (ex: substances in tobacco products)

2- Errors that occur when a cell replicates its DNA in preparation for cell division.

• Spontaneous• An enzyme may “fix” the wrong base.

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Types of Mutations

1.Base pair substitutions• (Aka Point mutation)

2.Frameshift mutation• deletions or insertions

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Base pair substitutions• The substitution

of one amino acid for another during protein synthesis.

• Can be harmless or it change the entire protein.

5757Point mutation

Base pair substitutions• The inherited disorder

sickle-cell anemia is caused by a this type of mutation.

5858Point mutation

Frameshift mutations-deletions or insertions

•When one or more base pairs are inserted into a DNA molecule or deleted from it.

•Causes a reading frame shift during translation.

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ACTIVITY

DNA TECHNOLOGY

forensicsforensics

agricultu

re

agricultu

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DNA fingerprinting

DNA fingerprinting

medicine medicine

industryindustry

genetic recombinationgenetic recombination..

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There are many uses for DNA technology. Police labs use DNA technology to identify people through a process known as DNA fingerprinting.

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ForensicsForensics

How to make a DNA

fingerprint

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• Scientist cut up DNA into pieces using enzymes- Restriction Enzymes

• Then load the pieces into a well.• Electricity is run through the gel.• The pieces of DNA move to the other end of

the gel with the + charge.• Smaller pieces move farther.• The gel is then compared to

a known sample

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Who doesn’t belong?

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Who done it?Who done it?•A blood stain

was found at a crime scene. Who is the perpetrator of the crime?

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•Researchers use recombinant DNA technology to analyze genetic changes. •They cut, splice together, & insert the modified DNA molecules from different species into bacteria or another type of cell that rapidly replicates and divides. •The cells copy the foreign DNA right along with their own DNA. •An example of this is the gene

for human insulin inserted into a bacterium. This is how human insulin is mass produced.

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Restriction Enzyme animation

Cloning a Gene

Bacteria DNA that has DNA from another

organism spliced in to it.

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•Sheep are used in the production of alpha-1 antitrypsin, which is used in the treatment of emphysema. •Goats are also producing the CFTR protein used in the treatment of cystic fibrosis.

agricultureagriculture

Called Transgenic Organisms

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In the plant world, the buds of cotton plants are vulnerable to worm attacks. The buds of a modified cotton plant resist these worms, resulting in increased cotton production.These gene insertions are ecologically safer than pesticides. They affect only the targeted pest.

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Plant biologists have used DNA technology to produce plants with many desirable traits. These include increased disease resistance, herbicide resistance, and increased nutritional content.

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Golden Rice23 times more Vitamin A

Called a Transgenic Organism

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Transgenic Organisms 7272

Transgenic Tobacco, from 1986. This is an ordinary photographic image of a tobacco plant engineered to express a firefly gene which produces luciferase.

Scientists today have developed Scientists today have developed genetically altered bacteria. genetically altered bacteria. Among them are strains of bacteria Among them are strains of bacteria that that

eat up oil spillseat up oil spillsmanufacture alcohol and other manufacture alcohol and other chemicalschemicalsprocess minerals. process minerals. Make human proteins.Make human proteins.

There is concern about possible risks There is concern about possible risks to the environment and the general to the environment and the general population as genetically engineered population as genetically engineered bacteria are introduced.bacteria are introduced.

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Cloning

Bill Nye

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