CHAPTER 12: DNA and RNA. Review 1.What organelle is known as the “control center” of the cell? 2.What structures are found in the nucleus? 3.What are.

CHAPTER 12:

DNA and RNA

Review

1. What organelle is known as the “control center” of the cell?

2. What structures are found in the nucleus?

3. What are located on chromosomes?

4. What are chromosomes composed of?

5. How do genes and chromosomes control the activity of the cell?

Griffith Experiment

Disease-causing bacteria (smooth

colonies)

Harmless bacteria (rough colonies)

Heat-killed, disease-causing bacteria (smooth colonies)

Control(no growth)



Dies of pneumonia Lives Lives Live, disease-causingbacteria (smooth colonies)

Dies of pneumonia

Section 12-1

Figure 12–2 Griffith’s Experiment

Disease-causing bacteria (smooth

colonies)



Control(no growth)



Dies of pneumonia Lives Lives Live, disease-causingbacteria (smooth colonies)

Dies of pneumonia

Section 12-1

Figure 12–2 Griffith’s Experiment

Transforming factor altered the Rough (harmless) Bacteria into Smooth (harmful) Bacteria

Avery, MacCleod, and McCardy Experiment

Avery, MacLeod and others

• Did the same experiment as Griffith except with isolating the biological compounds of Carbohydrates, Lipids, Proteins and DNA to see which when missing did not allow the transformation

• Only DNA was necessary for the transformation to occur; therefore it is the transforming factor.

Hershey and Chase Experiment

Bacteriophage with phosphorus-32 in DNA

Phage infectsbacterium

Radioactivity inside bacterium

Bacteriophage with sulfur-35 in protein coat


No radioactivity inside bacterium

Figure 12–4 Hershey-Chase ExperimentSection 12-1







Section 12-1

Figure 12–4 Hershey-Chase Experiment







Section 12-1

Figure 12–4 Hershey-Chase Experiment

Validated that DNA is the agent of genes

Chargaff Rule

Percentage of Bases in Four OrganismsSection 12-1

Source of DNA A T G CSource of DNA A T G C

Streptococcus 29.8 31.6 20.5 18.0

Yeast 31.3 32.9 18.7 17.1

Herring 27.8 27.5 22.2 22.6

Human 30.9 29.4 19.9 19.8

Streptococcus 29.8 31.6 20.5 18.0

Yeast 31.3 32.9 18.7 17.1

Herring 27.8 27.5 22.2 22.6

Human 30.9 29.4 19.9 19.8

Rosalind Franklin and Maurice Wilkins

But we must not forget Rosalind Franklin

Watson and Crick

Watson & Crick

http://www.ted.com/index.php/talks/james_watson_on_how_he_discovered_dna.html

http://www.ted.com/index.php/talks/james_watson_on_how_he_discovered_dna.html

A passion to KNOW

"You've got to be in it because you are actually curious about something. That's the fundamental. You can't go into science to be famous. You go into science because you are curious. That has to be the driving force."

--Watson

Evidence of DNA Structure

• X-Ray Diffraction– Rosalind Franklin and

Maurice Wilkins

• Chargaff base pairing– A-– G-

• Watson and Crick Final DNA model– Double – Nobel Prize winners in

1962

TC

Helix

Summary

Building block of DNA

• _____________ are the building block– Consist of:

• 5-Carbon sugar (Deoxyribose), • Phosphate group, and • Nitrogenous base:

– Adenine and Guanine : _____________– Thymine and Cytosine: _____________

• Sugar and Phosphate groups form __________ while nitrogenous bases ______________ in between.

Nucleotides

backbonehydrogen bond

Purines

Pyrimidines

Purines Pyrimidines

Adenine Guanine Cytosine Thymine

Phosphate group Deoxyribose

Figure 12–5 DNA Nucleotides

Section 12-1

Hydrogen bonds

Nucleotide

Sugar-phosphate backbone

Key

Adenine (A)

Thymine (T)

Cytosine (C)

Guanine (G)

Figure 12–7 Structure of DNA

Section 12-1

Summary of DNA structure

I Q #21. What is the genetic code? Why is it important?

2. What was Frederick Griffith studying originally?

3. Define Transformation

4. Avery, and colleagues discovered that DNA is the _______________.

5. Hershey and Chase worked with __________.

6. What is the building block of DNA? What is it composed of?

12-2: Chromosomes and DNA ReplicationA. DNA and Chromosomes

a. Prokaryotes ___________and their DNA is found in the cytoplasm.

b. It consists of a _____________________ DNA moleculec. This is the cells ______________d. Eukaryotic DNA is more complicatede. It is not free in the cytoplasm but is contained in the _________ of the cell.f. It forms a _______ of chromosomes not just oneg. humans have __, Drosophila have __ and a Sequoia tree have __.

lack nuclei

large, singular circular

chromosome

nucleusnumber

46 822

1. DNA Length

a. ____ molecules are surprisingly longb. prokaryotes DNA of E. coli is over __ million base pairs long.c. it must be ___________________ that is one-one thousandths it’s size. (see fig. 12-9)d. How does it do this?

DNA4

packed into a space

2. Chromosome Structure

a. DNA in ______________ is even more tightly packed.b. Eukaryotic DNA has over _______ DNA base pairs and is measured at over 1 meter of DNAc. It is folded into a tiny _____________d. How does it do this?e. Eukaryotic DNA contains both DNA and ________(proteins) packed together to form _________.

eukaryotic cells

6 billion

chromosome

histoneschromatin

2. Chromosome Structure (cont.)

f. Chromatin consists of ____ tightly wrapped around histones to form a _________ structure called a ___________.g. Nucleosomes pack with one another to form a thick fiber and are _________ by a system of ______________.h. During the _________ these fibers are dispersed and __________. i. During _________ they are condensed and coiled into the ________ chromosomes.j. What do nucleosomes do? _____________

_______________________________________ _______

DNAbeadlike

nucleosome

shortenedloops and coils

cell cyclenot visible

mitosisvisible

they are able to fold the DNA into the tiny space of the cell nucleus

DNA Supercoiling into Chromosomes

Chromosome

Supercoils

Coils

Nucleosome

Histones

DNA

double

helix

B. DNA ReplicationRemember what Watson and Crick learned about

DNA:- Holds the in the sequence of

nucleotides

- Is - consists of two parallel strands of sugar-phosphate groups. Pairs of nitrogenous bases link the two strands together, forming a

- The Nitrogen (N)-base pairing isbecause each strand can be used to make the other strand.

Genetic code

double stranded

double helix

complementary

B. DNA Replication- In ____________ replication begins on one

point on the chromosome and _________________________

- In __________ the DNA replication occurs in ________ of places and occurs in ____ _____________ until each chromosome is copied.

- The sites where separation and replication occur are called _______________.

prokaryotes continues in

two directions

eukaryoteshundreds both

directions

replication forks

The Structure of DNA

= Phosphate

= Deoxyribose

(5-c sugar)

= N-base

(A-T)

(G-C)

Hydrogen bonds

Try your own:

A A T T T C G A T G G C (Strand 1)

(Strand 2)

A.

This aids in DNA replication.

The Replication of DNA

T T A A A G C T A C C G

Each strand of the double helix serves as a template, or model, for the new strand

B. Q: Why does DNA need to replicate?

A:

C. DNA replication (aka: DNA synthesis) is

done with the aid of .


When a cell divides to form new cells, the DNA must REPLICATE to ensure new cells have a new copy.

Enzymes (DNA Polymerase)


D. The Enzymes:

1.

2.

3.

4.

Separate or “unzip” the two strands of the double helix.

Insert the appropriate bases.

Covalently bond the sugar to the phosphate

Proofread the bases to make sure they were paired correctly

Interactive DNA ReplicationA Science Odyssey: You Try It: DNA Workshop Activity

http://www.pbs.org/wgbh/aso/tryit/dna/shockwave.html

http://www.pbs.org/wgbh/aso/tryit/dna/shockwave.html

DNA Replication

Growth

Growth

Replication fork

DNA polymerase

New strand

Original strand DNA

polymerase

Nitrogenous bases

Replication fork

Original strand

New strand

The Replication of DNA (Summary)E. The steps in DNA replication

1.

2.

The Hydrogen Bonds (between N-bases) break and “unzips” the DNA

Each strand serves as a template for the attachment of complementary bases

http://www.abbysenior.com/biology/dna_protein_synthesis.htm

Unzip Base Pairing 2 New Strands


http://www.abbysenior.com/biology/dna_protein_synthesis.htm

12-3 RNA and Protein Synthesis• DNA holds the genetic code to make •

• DNA• How does DNA get the code outside the nucleus?

A:

DNA mRNA Protein

proteinsProteins are made outside the nucleus on ribosomes

Cannot leave the nucleus

RNA(Ribonucleic Acid) acts as a messenger between DNA and the ribosomes and carries out the process by which proteins are made from Amino Acids.

mRNA and DNA interaction

RNADNA

RNApolymerase

Adenine (DNA and RNA)Cystosine (DNA and RNA)Guanine(DNA and RNA)Thymine (DNA only)Uracil (RNA only)

I. The Structure of RNAA. Similar to DNA with a few differences:

DNA RNA

Strand

Sugar

Bases

Double Stranded

Deoxyribose

A-T G-C

Single Stranded (can form double strand if it folds back on itself).

Ribose

A-U G-C

The Structure of RNAB. 3 types of RNA:

1. mRNA (messenger RNA)

2. tRNA (transfer RNA)

3. rRNA (ribosomal RNA)

Copies the code off DNA in the nucleus and brings it out of the nucleus to the ribosomes

Carries amino acids to the ribosomes

Along with proteins, rRNA makes the subunits of the ribosomes

Different Forms of RNA

50S

30S

II. Transcription: RNA Synthesis

A. Transcription= The process by which a molecule of DNA is copied to a complementary strand of RNA

Page 147

Transcription: RNA Synthesis

B. Steps of Transcription: Step #1:

Step #2: RNA nucleotides base pair with

complementary DNA nucleotides

DNA

mRNA

RNA polymerase (enzyme) attaches to a sequence of DNA known as the Promotor and separates the 2 strands

A T C G

A CGU

with the help of RNA polymerase


Now try your own:

DNA= T T T A G A G A C C G T A T C

mRNA=

**Remember, RNA does not have Thymine!

A A A U C U C U G G C A U A G


Step #3:

Step #4:

RNA polymerase terminates (ends) transcription when it reaches the “STOP” site on the DNA

The final RNA strand leaves the nucleus through the pores in the nuclear envelope

• proteins are responsible for:– –

–

• DNA and RNA control the process of

• DNA RNA Protein

Controlling biochemical pathways(enzymes)

Synthesis of lipids, carbohydrates, and nucleotides

Cell structure and cell movement

making proteins

Transcription TranslationProtein Synthesis

I. THE NATURE OF THE GENETIC CODE

A. Review:1. Proteins are ________________ 2. Proteins are made of monomers known as _________________3. There are ___________ different kinds of amino acids4. Amino acids form

______________ bonds5. A string of amino acids is known

as a _______________

polymers

amino acids

20

peptide

polypeptide

The Nature of the Genetic Code

B. DNA contains

C. The code is copied onto

D. Every

E. Each

the code to make proteins

mRNA in transcription

3 nitrogenous bases on the mRNA makes a codon.

codon specifies an amino acid that is to be placed in the polypeptide chain

** the chart on page 303 lists the 64 codons for the amino acids

The Genetic Code (p. 303)

The Nature of the Genetic Code

Example:

DNA: T A C C A G C T C A C T mRNA:

Amino Acid:

F.

A AAU UU GG GGG C

Methionine

“Start” Codon

Valine Glutamic Acid

“Stop” Codon

An amino acid can have more than one codon

Example: Glycine GGG, GGA, GGU, GGC

II. TRANSLATION

A. Translation=

B. The_______________ language is ___________________ into ________________ language

The decoding of a mRNA into a polypeptide (protein)

nucleic acid

translated

protein

TranslationKEY PLAYERS

Ribosomal RNA

ANTICODON

Translation Steps of Translation:

Step #1: After leaving the nucleus,

Step #2: In the cytoplasm,

Step #3: First

mRNA binds to the ribosome where rRNA is found

tRNA picks up amino acids and carries them to the mRNA

the anticodon on tRNA attaches to the mRNA codon that it matches.

If the mRNA is AUG what will the anticodon be?

Step #4: Then

Step #5: As each

Step #6: Finally, when

tRNA continues to match its ANTICODONS with corresponding mRNA CODONS

anticodon and codon bind together, a peptide bond forms between the 2 amino acids

The ribosome reaches the stop codon on the mRNA the new polypeptide is released

Translation

Translation part 2

http://library.thinkquest.org/C0123260/basic%20knowledge/images/basic%20knowledge/RNA/translation%20steps.jpg

12-4 MutationsMutations in Genes =

A. Point Mutations = change involving a single nucleotide

Mutations that occur in individual genes. Can be changes in several or just one nucleotide

TYPE DEFINITION EXAMPLE

One base is replaced by another base

AGTGGATC

TCACCGAG

Nucleotide is removed AGTGGATC

AGTGATC

Nucleotide is added AGGTGGATC

AGGTGGATTC

Base substitution

Deletion

Insertion

Substitution InsertionDeletion

Gene Mutations:Substitution, Insertion, and Deletion

Go to Section:

B. ___________________ = codon groupings are shifted after deletion or insertion.

Frameshift Mutations

Chromosomal Mutations:Involve the movement of large sections of

chromosome

Deletion

Duplication

Inversion

Translocation

Answers 12-1

1. C2. B3. A4. Double helix5. Watson, Crick 6. Hydrogen bonds 7. Nucleotide8. Sugar-phosphate

backbone

9.

Sugar-phosphateBackbone

Hydrogen bonds

10.Approx. 28% of the bases would be thymine.

Answers 12-2

1. Separates2. Two; Four3. Base pairing4. Original strand5. New strand6. Original strand7. New strand8. By coiling and folding

very tightly, the DNA of a bacterium is able to fit inside the cell.

9. Typically, chromosomal fibers are dispersed and are not visible. During mitosis, however, they become so tightly packed together as to be visible under a light microscope.

Answers 12-3

1. Messenger RNA (mRNA), transfer RNA (tRNA), ribosomal RNA

2. Transcription

3. Polymerase

4. Translation

5. Anticodon

DNA•Thymine•Double stranded•Deoxyribose sugar

Both DNA & RNA•Consist of a long chain of nucleotides

RNA•Uracil •Single stranded•Ribose sugar

6. Compare & Contrast

Answers 12-3 cont.

mRNA carries protein assembly instructions

rRNA helps assemble proteins

tRNA carries amino acids used in the contruction of proteins

7.

Answer 12-3 cont.

8. Answers may vary.

Having a sequence of DNA that could be edited into several different mRNA makes it possible for a single gene to produce several different proteins specifically used in different tissues. This allows a cell to carry less genetic material. It also makes it possible for very small changes in DNA sequences to have a large change in gene expression. This is a mechanism for evolutionary change.

Answer 12-3 cont.

9. Arginine, tyrosine, and serine

10.During transcription, the DNA would produce mRNA in which the third base is C, not A. Translation, however, would be unaffected bkz the original and the altered codons, CGA and CGC, both specify the amino acid arginine.

Answers 12-4

1. Mutations2. Gene mutations3. Chromosomal mutation4. Deletion: involves the loss of all or part of a

chromosome5. Duplication: produces extra copies of parts of a

chromosome6. Inversion: reverses the direction of parts of

chromosomes 7. Translocation: occurs when a part of one

chromosome breaks off and attaches to another

Answers 12-4 cont.

8. Substitution and frameshift mutations are both point mutations, bkz they occur at a single point in the DNA sequence. However, a substitution affects only a single codon, whereas a frameshift mutation affects all the codons that follow the point of mutation.

Answers 12-4 cont.

9. Polyploid plants are often larger and stronger. This benefits humans by increasing agricultural production and the food supply.

10.An insertion, or frameshift mutation, has occurred.

References

http://blogs.sanmathi.org/anasuya/category/media/



CHAPTER 12: DNA and RNA. Review 1.What organelle is known as the “control center” of the cell? 2.What structures are found in the nucleus? 3.What are.

Documents

rough harmless bacteria

transformationonly dna

smooth harmful bacteriaavery

protein coatphage

chase experimentfigure

bacteriumno radioactivity

griffiths experimentdisease

transforming factor