Interest Grabber Order! Order!

Interest Grabber Order! Order!
Section 12-1 Order! Order! Genes are made of DNA, a large, complex molecule. DNA is composed of individual units called nucleotides. Three of these units form a code. The order, or sequence, of a code and the type of code determine the meaning of the message. 1. On a sheet of paper, write the word cats. List the letters or units that make up the word cats. 2. Try rearranging the units to form other words. Remember that each new word can have only three units. Write each word on your paper, and then add a definition for each word. 3. Did any of the codes you formed have the same meaning? 4. How do you think changing the order of the nucleotides in the DNA codon changes the codon’s message?

Section Outline 12–1 DNA A. Griffith and Transformation
1. Griffith’s Experiments 2. Transformation B. Avery and DNA C. The Hershey-Chase Experiment 1. Bacteriophages 2. Radioactive Markers D. The Components and Structure of DNA 1. Chargaff’s Rules 2. X-Ray Evidence 3. The Double Helix

Figure 12–2 Griffith’s Experiment
Section 12-1 Heat-killed, disease-causing bacteria (smooth colonies) Harmless bacteria (rough colonies) Control (no growth) Harmless bacteria (rough colonies) Heat-killed, disease-causing bacteria (smooth colonies) Disease-causing bacteria (smooth colonies) Dies of pneumonia Dies of pneumonia Lives Lives Live, disease-causing bacteria (smooth colonies)

Goals To learn the relationship between genes and DNA To learn the structure of DNA

Is there a molecule that carries the genetic code?
Many scientists tried to identify structures of genetic information to understand how genes control inheritance. Is there a molecule that carries the genetic code?

Frederick Griffith Originally, he was trying to determine the bacteria that caused pneumonia

Figure 12–2 Griffith’s Experiment
Section 12-1 Heat-killed, disease-causing bacteria (smooth colonies) Harmless bacteria (rough colonies) Control (no growth) Harmless bacteria (rough colonies) Heat-killed, disease-causing bacteria (smooth colonies) Disease-causing bacteria (smooth colonies) Dies of pneumonia Dies of pneumonia Lives Lives Live, disease-causing bacteria (smooth colonies)

One bacteria transformed into another. The disease causing ability?
Conclusion The heat-killed bacteria passed their disease causing ability to the harmless bacteria. One bacteria transformed into another. The disease causing ability? A Gene

Avery and other Scientists - 1944
Attempted to discover which molecule in the heat-killed bacteria caused the transformation. What substance made them (bacteria) change?

Transformation still occurred!
The scientists made an extract of the heat-killed bacteria and subjected it to enzymes that destroyed proteins, carbs, and lipids. Transformation still occurred! Obviously, proteins, carbs, and lipids were NOT involved with transformation.

Transformation did NOT occur! DNA was the transforming factor!!!
Then Avery and his team subjected the extract to enzymes that would break down DNA. Transformation did NOT occur! DNA was the transforming factor!!!

Avery and others made a discovery…
DNA stores and transmits genetic information from one generation to the next.

The Hershey – Chase Experiment 1952
These scientists were skeptical about the results from Avery etal. They designed an experiment to see if genes were actually made up of proteins or DNA

The Hershey – Chase Experiment 1952
They used bacteriophages and radioactive markers

A virus that infects bacteria
Bacteriophage A virus that infects bacteria

How does the virus function?

Radioactive Markers To determine if genes were actually made up of proteins or DNA, they grew viruses in cultures containing radioactive isotopes Phosphorous – 32 (32P) Sulfur – 35 (35S)

This was a clever strategy…
Radioactive Markers Phosphorous – 32 (32P) Sulfur – 35 (35S) This was a clever strategy… There is no phosphorous in protein, and no sulfur in DNA.

There is no phosphorous in protein, and no sulfur in DNA.
Therefore, if 35S is found in the bacteria, the virus injected protein to alter the cell. If 32P is found in the bacteria, the virus injected DNA to alter the cell.

Figure 12–4 Hershey-Chase Experiment
Section 12-1 Bacteriophage with phosphorus-32 in DNA Phage infects bacterium Radioactivity inside bacterium Bacteriophage with sulfur-35 in protein coat Phage infects bacterium No radioactivity inside bacterium

The radioactive marked DNA was found in the bacteria cell.
Conclusion The genetic material of the bacteriophage was DNA, not protein. In other words, genes are made from DNA.

DNA Structure and Components
Read p. 291

DNA is a very long molecule made up of nucleotides.
Nucleotides have three basic components:

Nucleotide Phosphate Group 5 carbon sugar Deoxyribose Nitrogenous base

There are four types of nucleotides based upon the nitrogenous bases.
DNA There are four types of nucleotides based upon the nitrogenous bases. Adenine - Thymine Guanine - Cytosine

The molecule is supported by a sugar-phosphate backbone.
DNA The molecule is supported by a sugar-phosphate backbone.

Figure 12–5 DNA Nucleotides
Section 12-1 Purines Pyrimidines Adenine Guanine Cytosine Thymine Phosphate group Deoxyribose

Figure 12–7 Structure of DNA
Section 12-1 Nucleotide Hydrogen bonds Sugar-phosphate backbone Key Adenine (A) Thymine (T) Cytosine (C) Guanine (G)

Research that led scientists to discover the structure of DNA.
Chargaff’s Rules Through intensive research he observed that for a variety of organisms, there are near equal amounts of certain types of nucleotides.

Percentage of Bases in Four Organisms
Section 12-1 Source of DNA A T G C Streptococcus Yeast Herring Human

Chargaff’s Rules or Base Pairing
Research that led scientists to discover the structure of DNA. The results from Chargaff’s research led scientists to understand that A-T and G-C Chargaff’s Rules or Base Pairing

X-ray Evidence Rosalind Franklin used this special technique to show that the strands of DNA are twisted around each other.

The combination of Chargaff’s Rules and Franklin’s X-ray diffraction led Watson and Crick to discovering the structure of DNA. Nobel Peace Prize 1962 Read p. 293

Interest Grabber A Perfect Copy
Section 12-2 A Perfect Copy When a cell divides, each daughter cell receives a complete set of chromosomes. This means that each new cell has a complete set of the DNA code. Before a cell can divide, the DNA must be copied so that there are two sets ready to be distributed to the new cells.

Interest Grabber continued
Section 12-2 1. On a sheet of paper, draw a curving or zig-zagging line that divides the paper into two halves. Vary the bends in the line as you draw it. Without tracing, copy the line on a second sheet of paper. 2. Hold the papers side by side, and compare the lines. Do they look the same? 3. Now, stack the papers, one on top of the other, and hold the papers up to the light. Are the lines the same? 4. How could you use the original paper to draw exact copies of the line without tracing it? 5. Why is it important that the copies of DNA that are given to new daughter cells be exact copies of the original?

Section Outline 12–2 Chromosomes and DNA Replication
A. DNA and Chromosomes 1. DNA Length 2. Chromosome Structure B. DNA Replication 1. Duplicating DNA 2. How Replication Occurs

Goals What happens during DNA Replication?

DNA is located in the cytoplasm
Prokaryotic Cells DNA is located in the cytoplasm

Prokaryotic Chromosome Structure
Section 12-2 Chromosome E. coli bacterium Bases on the chromosome

DNA is located in the nucleus in the form of chromosomes
Eukaryotic Cells DNA is located in the nucleus in the form of chromosomes The number of chromosomes varies widely from one species to the next. Human - 46 Fruit Fly - 8 Bread Wheat 42 Goldfish - 100 Corn - 20 Apes- 48

E. Coli – more than 4 million base pairs.
DNA Length E. Coli – more than 4 million base pairs. Highly coiled and folded, but when straightened, it can be as long as 1.6mm. Human DNA is 1000x as long See Fig. 12-9

Figure 12-10 Chromosome Structure of Eukaryotes
Section 12-2 Nucleosome Chromosome DNA double helix Coils Supercoils Histones

Duplicating DNA DNA is replicated before the cell divides (which phase of the cell cycle?)

Figure 12–11 DNA Replication

During DNA replication, the DNA molecule separates into two strands.
Produces two NEW complementary strands following the rules of base pairing. A – T and G - C Each strand of the double helix of DNA serves as a template for the new strand

How Replication Occurs
Enzymes “unzip” the two strands. The H bonds between the base pairs are broken and the two strands unwind.

Section 12-2 Original strand DNA polymerase New strand Growth DNA polymerase Growth Replication fork Replication fork Nitrogenous bases New strand Original strand

How Replication Occurs
2. New base pairs are added following the base pair rules. DNA polymerase joins nucleotides to produce a new DNA molecule. DNA polymerase also “proofreads” each new strand.

Result Each DNA molecule formed from replication has one original strand and one NEW strand.

Section 12-2 Original strand DNA polymerase New strand Growth DNA polymerase Growth Replication fork Replication fork Nitrogenous bases New strand Original strand

Sooooo What!?! Why is this important?
The reason that Watson and Crick’s discovery is so important is that they explained how DNA can be replicated.

Sooooo What?!! Why is this important?
In other words, they helped explain how the GENETIC CODE can be copied and passed from generation to generation!!! Read p. 297

Interest Grabber Information, Please
Section 12-3 Information, Please DNA contains the information that a cell needs to carry out all of its functions. In a way, DNA is like the cell’s encyclopedia. Suppose that you go to the library to do research for a science project. You find the information in an encyclopedia. You go to the desk to sign out the book, but the librarian informs you that this book is for reference only and may not be taken out. 1. Why do you think the library holds some books for reference only? 2. If you can’t borrow a book, how can you take home the information in it? 3. All of the parts of a cell are controlled by the information in DNA, yet DNA does not leave the nucleus. How do you think the information in DNA might get from the nucleus to the rest of the cell?

Section Outline 12–3 RNA and Protein Synthesis A. The Structure of RNA
B. Types of RNA C. Transcription D. RNA Editing E. The Genetic Code F. Translation G. The Roles of RNA and DNA H. Genes and Proteins

Recognize and learn three main types of RNA
Goals Recognize and learn three main types of RNA Understand transcription Understand translation

Nucleotides are the monomers (building blocks)
RNA structure… is similar to DNA Nucleotides are the monomers (building blocks) Five carbon sugar Phosphate group Nitrogenous bases

Three Major Differences
DNA and RNA Three Major Differences DNA RNA sugars strands Nitrogenous bases Deoxyribose Ribose Double Single A T G C A U G C

Three Types of RNA In the majority of cells, most RNA molecules are involved in protein synthesis.

mRNA Messenger RNA Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only) Carries copies of the genetic information from the DNA to the ribosomes.

rRNA combines with proteins to make up ribosomes.
rRNA Ribosomal RNA rRNA combines with proteins to make up ribosomes.

tRNA Transfer RNA Transfers a specific amino acid to the ribosomes during protein synthesis.

Creating a copy of a DNA sequence into an mRNA sequence
Transcription “Re-writing” the code Creating a copy of a DNA sequence into an mRNA sequence

1. RNA polymerase separates DNA strands.
Figure 12–14 Transcription Transcription 1. RNA polymerase separates DNA strands. Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only) 2. One of the DNA strands is used as a template to assemble an mRNA strand. 3. “Promoters” are used to start and stop the mRNA sequence.

1. Where is DNA located in the eukaryotic cell?
Figure 12–14 Transcription 1. Where is DNA located in the eukaryotic cell? Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only) 2. Where does transcription take place? 3. Where does protein synthesis take place?

The genetic code is the “language” of mRNA.
Figure 12–17 The Genetic Code The Genetic Code The genetic code is the “language” of mRNA. It is a code of three letters from an “alphabet” of four letters… Codon – Three nucleotides (letters) that specify for a single amino acid

Codon – Three nucleotides (letters) that specify for a single amino acid
CCC AGG UCC GAG AUG UGG

Figure 12–17 The Genetic Code

Codon – Three nucleotides (letters) that specify for a single amino acid
UCG CAC GGU Serine Histidine Glycine

Start Codon – signals for the beginning of protein synthesis.
AUG Methionine Stop Codon – signals for the end of protein synthesis.

A certain gene (DNA segment) has the following sequence of nucleotides:
TACAAGTCCACAATC From left to right, write the sequence of the mRNA molecule related to this gene. (What is this process called?)

Methionine (Start) – Phenylalanine – Arginine – Cysteine - Stop
TACAAGTCCACAATC AUGUUCAGGUGUUAG Write the amino acid sequence of the polypeptide translated from the mRNA. Methionine (Start) – Phenylalanine – Arginine – Cysteine - Stop

The decoding of an mRNA message into a polypeptide chain (protein)
Translation The decoding of an mRNA message into a polypeptide chain (protein)

1. mRNA is transcribed from DNA in the nucleus
Figure 12–18 Translation 1. mRNA is transcribed from DNA in the nucleus

2. mRNA goes to the ribosome.
Figure 12–18 Translation 2. mRNA goes to the ribosome.

3. tRNA brings the proper amino acid to the ribosome.
Figure 12–18 Translation 3. tRNA brings the proper amino acid to the ribosome.

tRNA – a very special molecule
Figure 12–18 Translation tRNA – a very special molecule It is composed of a “loop” of RNA that has three exposed nitrogenous bases. anticodon

The anticodon is complementary to a codon of mRNA
mRNA AUGUUCAGGUGUUAG tRNA UACAAGUCCACAAUC Each tRNA is specific for a certain amino acid

A polypeptide chain (protein) is assembled using many amino acids.
Figure 12–18 Translation A polypeptide chain (protein) is assembled using many amino acids.

Figure 12–18 Translation (continued)

Read p. 306

Bring amino acids to ribosome
Concept Map Section 12-3 RNA can be Messenger RNA Ribosomal RNA Transfer RNA also called which functions to also called which functions to also called which functions to mRNA Carry instructions rRNA Combine with proteins tRNA Bring amino acids to ribosome from to to make up DNA Ribosome Ribosomes

Figure 12–14 Transcription
Section 12-3 Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only) RNA polymerase DNA RNA

Figure 12–17 The Genetic Code
Section 12-3

Figure 12–18 Translation Section 12-3

Figure 12–18 Translation (continued)
Section 12-3

Interest Grabber Determining the Sequence of a Gene
Section 12-4 Determining the Sequence of a Gene DNA contains the code of instructions for cells. Sometimes, an error occurs when the code is copied. Such errors are called mutations.

Section 12-4 1. Copy the following information about Protein X: Methionine—Phenylalanine—Tryptophan—Asparagine—Isoleucine—STOP. 2. Use Figure 12–17 on page 303 in your textbook to determine one possible sequence of RNA to code for this information. Write this code below the description of Protein X. Below this, write the DNA code that would produce this RNA sequence. 3. Now, cause a mutation in the gene sequence that you just determined by deleting the fourth base in the DNA sequence. Write this new sequence. 4. Write the new RNA sequence that would be produced. Below that, write the amino acid sequence that would result from this mutation in your gene. Call this Protein Y. 5. Did this single deletion cause much change in your protein? Explain your answer.

Section Outline 12–4 Mutations A. Kinds of Mutations 1. Gene Mutations
2. Chromosomal Mutations B. Significance of Mutations

Mutant apples

For pedicures, do they charge by the toe?

Mutation - Changes in genetic material A mistake in DNA replication

Two Types of Mutation Gene Mutations Chromosome Mutations

Changes in a single gene
Gene Mutations Changes in a single gene These mutations are also called point mutations … … because they occur at a single point in the DNA sequence. These mutations results in changes in one or a few nucleotides.

Three Types of Gene Mutations
Substitutions, Insertions, and Deletions

Substitution Mutations usually affect no more than a single amino acid

Gene Mutations: Substitution, Insertion, and Deletion
Section 12-4 Deletion Substitution Insertion

Insertions and Deletions
Changes in the DNA are more dramatic. Therefore these mutations can affect several amino acids.

Insertion

Deletion

Chromosomal Mutations
These mutations changes the number and structure of chromosomes.

Figure 12–20 Chromosomal Mutations
Section 12-4 Deletion Duplication Inversion Translocation

Significance of Mutations
Most mutations are neutral…they do not disrupt biological activities

Some mutations are harmful:
They can change protein structure or gene activity. Genetic Disorders: cancer, sickle cell anemia

Adds to Genetic Variability!
Beneficial Mutations May produce proteins with new activities that are useful in changing environments. Adds to Genetic Variability!

Read p. 308

Interest Grabber Regulation of Protein Synthesis
Section 12-5 Regulation of Protein Synthesis Every cell in your body, with the exception of gametes, or sex cells, contains a complete copy of your DNA. Why, then, are some cells nerve cells with dendrites and axons, while others are red blood cells that have lost their nuclei and are packed with hemoglobin? Why are cells so different in structure and function? If the characteristics of a cell depend upon the proteins that are synthesized, what does this tell you about protein synthesis? Work with a partner to discuss and answer the questions that follow.

Section 12-5 1. Do you think that cells produce all the proteins for which the DNA (genes) code? Why or why not? How do the proteins made affect the type and function of cells? 2. Consider what you now know about genes and protein synthesis. What might be some ways that a cell has control over the proteins it produces? 3. What type(s) of organic compounds are most likely the ones that help to regulate protein synthesis? Justify your answer.

Section Outline 12–5 Gene Regulation A. Gene Regulation: An Example
B. Eukaryotic Gene Regulation C. Development and Differentiation

Typical Gene Structure
Section 12-5 Promoter (RNA polymerase binding site) Regulatory sites DNA strand Start transcription Stop transcription

Click a hyperlink to choose a video. Griffith’s Experiment
Videos Click a hyperlink to choose a video. Griffith’s Experiment DNA Replication DNA Transcription Protein Synthesis Duplication and Deletion Translocation and Inversion Point Mutations Video Contents

Click the image to play the video segment.
Griffith’s Experiment Click the image to play the video segment. Video 1

DNA Replication Click the image to play the video segment. Video 2

DNA Transcription Click the image to play the video segment. Video 3

Protein Synthesis Click the image to play the video segment. Video 4

Duplication and Deletion Click the image to play the video segment. Video 5

Translocation and Inversion Click the image to play the video segment. Video 6

Point Mutations Click the image to play the video segment. Video 7

Go Online Interactive test Articles on genetics
For links on DNA, go to and enter the Web Code as follows: cbn-4121. For links on DNA replication, go to and enter Web Code as follows: cbn-4122. For links on protein synthesis, go to and enter the Web Code as follows: cbn-4123. Internet

Interest Grabber Answers
1. On a sheet of paper, write the word cats. List the letters or units that make up the word cats. The units that make up cats are c, a, t, and s. 2. Try rearranging the units to form other words. Remember that each new word can have only three units. Write each word on your paper, and then add a definition for each word. Student codes may include: Act; Sat; Cat 3. Did any of the codes you formed have the same meaning? No 4. How do you think changing the order of the nucleotides in the DNA codon changes the codon’s message? Changing the order of the nucleotides changes the meaning of the codon. Section 1 Answers

1. On a sheet of paper, draw a curving or zig-zagging line that divides the paper into two halves. Vary the bends in the line as you draw it. Without tracing, copy the line on a second sheet of paper. 2. Hold the papers side by side, and compare the lines. Do they look the same? Lines will likely look similar. 3. Now, stack the papers, one on top of the other, and hold the papers up to the light. Are the lines the same? Overlaying the papers will show variations in the lines. 4. How could you use the original paper to draw exact copies of the line without tracing it? Possible answer: Cut along the line and use it as a template to draw the line on another sheet of paper. 5. Why is it important that the copies of DNA that are given to new daughter cells be exact copies of the original? Each cell must have the correct DNA, or the cell will not have the correct characteristics. Section 2 Answers

1. Why do you think the library holds some books for reference only? Possible answers: The books are too valuable to risk loss or damage to them. The library wants to make sure the information is always available and not tied up by one person. 2. If you can’t borrow a book, how can you take home the information in it? Students may suggest making a photocopy or taking notes. 3. All of the parts of a cell are controlled by the information in DNA, yet DNA does not leave the nucleus. How do you think the information in DNA might get from the nucleus to the rest of the cell? Students will likely say that the cell has some way to copy the information without damaging the DNA. Section 3 Answers

1. Copy the following information about Protein X: Methionine—Phenylalanine—Tryptophan—Asparagine—Isoleucine—STOP. 2. Use Figure 12–17 on page 303 in your textbook to determine one possible sequence of RNA to code for this information. Write this code below the description of Protein X. Below this, write the DNA code that would produce this RNA sequence. Sequences may vary. One example follows: Protein X: mRNA: AUG-UUU-UGG-AAU-AUU-UGA; DNA: TAC-AAA-ACC-TTA-TAA-ACT 3. Now, cause a mutation in the gene sequence that you just determined by deleting the fourth base in the DNA sequence. Write this new sequence. (with deletion of 4th base U) DNA: TAC-AAA-CCT-TAT-AAA-CT 4. Write the new RNA sequence that would be produced. Below that, write the amino acid sequence that would result from this mutation in your gene. Call this Protein Y. mRNA: AUG-UUU-GGA-AUA-UUU-GA Codes for amino acid sequence: Methionine— Phenylalaine—Glycine—Isoleucine—Phenylalanine—? 5. Did this single deletion cause much change in your protein? Explain your answer. Yes, Protein Y was entirely different from Protein X. Section 4 Answers

1. Do you think that cells produce all the proteins for which the DNA (genes) code? Why or why not? How do the proteins made affect the type and function of cells? Cells do not make all of the proteins for which they have genes (DNA). The structure and function of each cell are determined by the types of proteins present. 2. Consider what you now know about genes and protein synthesis. What might be some ways that a cell has control over the proteins it produces? There must be certain types of compounds that are involved in determining what types of mRNA transcripts are made and when this mRNA translates at the ribosome. 3. What type(s) of organic compounds are most likely the ones that help to regulate protein synthesis? Justify your answer. The type of compound responsible is probably a protein, specifically enzymes, because these catalyze the chemical reactions that take place. Section 5 Answers

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