Biology Copyright Pearson Prentice Hall.

Biology Copyright Pearson Prentice Hall

12–1 DNA Photo credit: Jacob Halaska/Index Stock Imagery, Inc.
Copyright Pearson Prentice Hall

Bell Work 4-20-2015 What is the control center of a cell?
What are the 3 critical things genes were known to do by the early scientist? (p. 291) Learning Target I can explain how scientist discovered the relationship between genes and DNA.

Learning Target I can explain how scientist discovered the relationship between genes and DNA. Agenda: Bell Work / LT Biologist Timeline

?????? What was Fredrick Griffith trying to learn? Why was he trying to learn how bacteria made people sick? Why is it important to learn how bacteria causes diseases?

Griffith and Transformation
In 1928, British scientist Fredrick Griffith was trying to learn how certain types of bacteria caused pneumonia. He isolated two different strains of pneumonia bacteria from mice and grew them in his lab.

Griffith made two observations: (1) The disease-causing strain of bacteria grew into smooth colonies on culture plates. (2) The harmless strain grew into colonies with rough edges.

Who can describe Griffiths first experiment?

Griffith's Experiments Griffith set up four individual experiments. Experiment 1: Mice were injected with the disease-causing strain of bacteria. The mice developed pneumonia and died. Griffith injected mice with four different samples of bacteria. When injected separately, neither heat-killed, disease-causing bacteria nor live, harmless bacteria killed the mice. The two types injected together, however, caused fatal pneumonia. From this experiment, biologists inferred that genetic information could be transferred from one bacterium to another.

Second experiment?

Experiment 2: Mice were injected with the harmless strain of bacteria. These mice didn’t get sick. Harmless bacteria (rough colonies) Griffith injected mice with four different samples of bacteria. When injected separately, neither heat-killed, disease-causing bacteria nor live, harmless bacteria killed the mice. The two types injected together, however, caused fatal pneumonia. From this experiment, biologists inferred that genetic information could be transferred from one bacterium to another. Lives

Third experiment? Copyright Pearson Prentice Hall

Experiment 3: Griffith heated the disease- causing bacteria. He then injected the heat-killed bacteria into the mice. The mice survived. Heat-killed disease-causing bacteria (smooth colonies) Griffith injected mice with four different samples of bacteria. When injected separately, neither heat-killed, disease-causing bacteria nor live, harmless bacteria killed the mice. The two types injected together, however, caused fatal pneumonia. From this experiment, biologists inferred that genetic information could be transferred from one bacterium to another. Lives

Fourth experiment? Copyright Pearson Prentice Hall

Experiment 4: Griffith mixed his heat-killed, disease-causing bacteria with live, harmless bacteria and injected the mixture into the mice. The mice developed pneumonia and died. Griffith injected mice with four different samples of bacteria. When injected separately, neither heat-killed, disease-causing bacteria nor live, harmless bacteria killed the mice. The two types injected together, however, caused fatal pneumonia. From this experiment, biologists inferred that genetic information could be transferred from one bacterium to another.

What did Griffith conclude?

Griffith concluded that the heat- killed bacteria passed their disease-causing ability to the harmless strain. Griffith injected mice with four different samples of bacteria. When injected separately, neither heat-killed, disease-causing bacteria nor live, harmless bacteria killed the mice. The two types injected together, however, caused fatal pneumonia. From this experiment, biologists inferred that genetic information could be transferred from one bacterium to another. Copyright Pearson Prentice Hall

What did Griffith call this process of changing one molecule into another?

Griffith called this process transformation because one strain of bacteria (the harmless strain) had changed permanently into another (the disease- causing strain). Griffith hypothesized that a factor must contain information that could change harmless bacteria into disease-causing ones. Copyright Pearson Prentice Hall

What did Avery want to determine?

Avery and DNA Avery and DNA Oswald Avery repeated Griffith’s work to determine which molecule was most important for transformation. Avery and his colleagues made an extract from the heat-killed bacteria that they treated with enzymes. Copyright Pearson Prentice Hall

How did Avery go about this testing?

Avery and DNA The enzymes destroyed proteins, lipids, carbohydrates, and other molecules, including the nucleic acid RNA. Transformation still occurred.

What is the next step Avery took?

Avery and DNA Avery and other scientists repeated the experiment using enzymes that would break down DNA. When DNA was destroyed, transformation did not occur. Therefore, they concluded that DNA was the transforming factor.

What was Avery's conclusion?

Avery and DNA Avery and other scientists discovered that the nucleic acid DNA stores and transmits the genetic information from one generation of an organism to the next.

What question did Hershey and Chase want answers to?

The Hershey-Chase Experiment
Alfred Hershey and Martha Chase studied viruses—nonliving particles smaller than a cell that can infect living organisms. The Hershey-Chase Experiment Copyright Pearson Prentice Hall

Wanted to know if genes were made of protein or DNA. Bacteriophages A virus that infects bacteria is known as a bacteriophage. Bacteriophages are composed of a DNA or RNA core and a protein coat. Copyright Pearson Prentice Hall

How did they go about their experiment?

They grew viruses in cultures containing radioactive isotopes of phosphorus-32 (32P) and sulfur-35 (35S).

If 35S was found in the bacteria, it would mean that the viruses’ protein had been injected into the bacteria. Alfred Hershey and Martha Chase used different radioactive markers to label the DNA and proteins of bacteriophages. The bacteriophages injected only DNA into the bacteria, not proteins. From these results, Hershey and Chase concluded that the genetic material of the bacteriophage was DNA. Phage infects bacterium Bacteriophage with suffur-35 in protein coat No radioactivity inside bacterium

If 32P was found in the bacteria, then it was the DNA that had been injected. Alfred Hershey and Martha Chase used different radioactive markers to label the DNA and proteins of bacteriophages. The bacteriophages injected only DNA into the bacteria, not proteins. From these results, Hershey and Chase concluded that the genetic material of the bacteriophage was DNA. Bacteriophage with phosphorus-32 in DNA Phage infects bacterium Radioactivity inside bacterium

What did they find in the bacteria?

Nearly all the radioactivity in the bacteria was from phosphorus (32P). Hershey and Chase concluded that the genetic material of the bacteriophage was DNA, not protein.

The Components and Structure of DNA
DNA is made up of nucleotides. A nucleotide is a monomer of nucleic acids made up of: Deoxyribose – 5-carbon Sugar Phosphate Group Nitrogenous Base

There are four kinds of bases in in DNA: adenine guanine cytosine thymine DNA is made up of nucleotides. Each nucleotide has three parts: a deoxyribose molecule, a phosphate group, and a nitrogenous base. There are four different bases in DNA: adenine, guanine, cytosine, and thymine. Copyright Pearson Prentice Hall

Chargaff's Rules Erwin Chargaff discovered that: The percentages of guanine [G] and cytosine [C] bases are almost equal in any sample of DNA. The percentages of adenine [A] and thymine [T] bases are almost equal in any sample of DNA. Copyright Pearson Prentice Hall

X-Ray Evidence Rosalind Franklin used X-ray diffraction to get information about the structure of DNA. She aimed an X-ray beam at concentrated DNA samples and recorded the scattering pattern of the X- rays on film. This X-ray diffraction photograph of DNA was taken by Rosalind Franklin in the early 1950s. The X-shaped pattern in the center indicates that the structure of DNA is helical. Photo credit: ©Cold Spring Harbor Laboratory Archives/Peter Arnold, Inc.

The Double Helix Using clues from Franklin’s pattern, James Watson and Francis Crick built a model that explained how DNA carried information and could be copied. Watson and Crick's model of DNA was a double helix, in which two strands were wound around each other.

DNA Double Helix DNA is a double helix in which two strands are wound around each other. Each strand is made up of a chain of nucleotides. The two strands are held together by hydrogen bonds between adenine and thymine and between guanine and cytosine.

Watson and Crick discovered that hydrogen bonds can form only between certain base pairs—adenine and thymine, and guanine and cytosine. This principle is called base pairing.

Bell Work 4-21-2015 What does a double helix look like?
Use the scissors on your desk to cut out the pieces for a double helix. Learning Target. I can explain a double helix.

Learning Target. I can explain a double helix. Agenda Bell Work / LT Plickers Activity Discussion

Bell Work 4-22-2015 What does a double helix look like?
What is the pattern for base pairing? Name the molecules that make up the sides of the DNA Ladder. Learning Target I can explain the structure of a double helix.

I can explain the structure of a double helix.
Learning Target I can explain the structure of a double helix. Agenda Bell Work / LT Review Assignment Activity Plickers Copyright Pearson Prentice Hall

12–1 Avery and other scientists discovered that
DNA is found in a protein coat. DNA stores and transmits genetic information from one generation to the next. transformation does not affect bacteria. proteins transmit genetic information from one generation to the next. Copyright Pearson Prentice Hall

12–1 The Hershey-Chase experiment was based on the fact that
DNA has both sulfur and phosphorus in its structure. protein has both sulfur and phosphorus in its structure. both DNA and protein have no phosphorus or sulfur in their structure. DNA has only phosphorus, while protein has only sulfur in its structure. Copyright Pearson Prentice Hall

12–1 DNA is a long molecule made of monomers called nucleotides.
purines. pyrimidines. sugars. Copyright Pearson Prentice Hall

12–1 Chargaff's rules state that the number of guanine nucleotides must equal the number of cytosine nucleotides. adenine nucleotides. thymine nucleotides. thymine plus adenine nucleotides. Copyright Pearson Prentice Hall

12–1 In DNA, the following base pairs occur: A with C, and G with T.
A with T, and C with G. A with G, and C with T. A with T, and C with T. Copyright Pearson Prentice Hall

12-2 Chromosomes and DNA Replication
Photo credit: Jacob Halaska/Index Stock Imagery, Inc. Copyright Pearson Prentice Hall

Bell Work Considering your knowledge of DNA, what might happen if bases paired incorrectly? What is the pattern for base pairing? Name the molecules that make up the sides of the DNA Ladder. Learning Target I can explain DNA replication.

Learning Target I can explain DNA replication. Agenda Bell Work / LT Discussion of RNA Assignment Quizlet

Research Where is DNA found in both prokaryotic and eukaryotic cells?

In prokaryotic cells, DNA is located in the cytoplasm.
DNA and Chromosomes DNA and Chromosomes In prokaryotic cells, DNA is located in the cytoplasm. Most prokaryotes have a single DNA molecule containing nearly all of the cell’s genetic information. Copyright Pearson Prentice Hall

E. Coli Bacterium DNA and Chromosomes Chromosome
Most prokaryotes, such as this E. coli bacterium, have only a single circular chromosome. This chromosome holds most of the organism’s DNA. E. Coli Bacterium Bases on the Chromosomes Copyright Pearson Prentice Hall

Many eukaryotes have 1000 times the amount of DNA as prokaryotes.
DNA and Chromosomes Many eukaryotes have 1000 times the amount of DNA as prokaryotes. Eukaryotic DNA is located in the cell nucleus inside chromosomes. number of chromosomes varies widely from one species to the next. Copyright Pearson Prentice Hall

DNA and histone molecules form nucleosomes.
DNA and Chromosomes Chromosome Structure Eukaryotic chromosomes contain DNA and protein, tightly packed together to form chromatin. Chromatin consists of DNA tightly coiled around proteins called histones. DNA and histone molecules form nucleosomes. Nucleosomes pack together, forming a thick fiber. Copyright Pearson Prentice Hall

DNA and Chromosomes Chromosome Nucleosome DNA double helix Coils
Eukaryotic Chromosome Structure Chromosome Nucleosome DNA double helix Coils Supercoils Eukaryotic chromosomes contain DNA wrapped around proteins called histones. The strands of nucleosomes are tightly coiled and supercoiled to form chromosomes. Histones Copyright Pearson Prentice Hall

Research What is DNA Replication?

DNA Replication DNA Replication Each strand of the DNA double helix has all the information needed to reconstruct the other half by the mechanism of base pairing. In most prokaryotes, DNA replication begins at a single point and continues in two directions. Copyright Pearson Prentice Hall

DNA Replication In eukaryotic chromosomes, DNA replication occurs at hundreds of places. Replication proceeds in both directions until each chromosome is completely copied. The sites where separation and replication occur are called replication forks. Copyright Pearson Prentice Hall

DNA Replication Duplicating DNA Before a cell divides, it duplicates its DNA in a process called replication. Replication ensures that each resulting cell will have a complete set of DNA. Copyright Pearson Prentice Hall

DNA Replication During DNA replication, the DNA molecule separates into two strands, then produces two new complementary strands following the rules of base pairing. Each strand of the double helix of DNA serves as a template for the new strand. Copyright Pearson Prentice Hall

DNA Replication New Strand Original strand Nitrogen Bases Growth
During DNA replication, the DNA molecule produces two new complementary strands. Each strand of the double helix of DNA serves as a template for the new strand. Replication Fork Replication Fork DNA Polymerase Copyright Pearson Prentice Hall

Research How does replication occur? Copyright Pearson Prentice Hall

How Replication Occurs
DNA replication is carried out by enzymes that “unzip” a molecule of DNA. Hydrogen bonds between base pairs are broken and the two strands of DNA unwind. Copyright Pearson Prentice Hall

The principal enzyme involved in DNA replication is…. DNA polymerase
joins individual nucleotides to produce a DNA molecule and then “proofreads” each new DNA strand. Copyright Pearson Prentice Hall

12–2 In prokaryotic cells, DNA is found in the cytoplasm. nucleus.
ribosome. cell membrane. Copyright Pearson Prentice Hall

12–2 The first step in DNA replication is producing two new strands.
separating the strands. producing DNA polymerase. correctly pairing bases. Copyright Pearson Prentice Hall

12–2 A DNA molecule separates, and the sequence GCGAATTCG occurs in one strand. What is the base sequence on the other strand? GCGAATTCG CGCTTAAGC TATCCGGAT GATGGCCAG Copyright Pearson Prentice Hall

12–2 In addition to carrying out the replication of DNA, the enzyme DNA polymerase also functions to unzip the DNA molecule. regulate the time copying occurs in the cell cycle. “proofread” the new copies to minimize the number of mistakes. wrap the new strands onto histone proteins. Copyright Pearson Prentice Hall

12–2 The structure that may play a role in regulating how genes are “read” to make a protein is the coil. histone. nucleosome. chromatin. Copyright Pearson Prentice Hall

12-3 RNA and Protein Synthesis

Bell Work What might you compare the looks of a supercoiled nucleosome to that you are familiar? What is chromatin? What is the job of a nucleosome? Learning Target I can explain the how RNA differs from DNA.

Learning Target I can explain the how RNA differs from DNA. Agenda Bell Work / LT Discussion of RNA Activity / Assignment Plickers Quizlet

Research How does a gene Work? Copyright Pearson Prentice Hall

12–3 RNA and Protein Synthesis
How does a gene Work? 1. Genes are coded DNA instructions that control the production of proteins. 2. Genetic messages can be decoded by copying part of the nucleotide sequence from DNA into RNA. 3. RNA contains coded information for making proteins. Copyright Pearson Prentice Hall

Research What is the structure of RNA compare to DNA?

Copyright Pearson Prentice Hall
The Structure of RNA The Structure of RNA There are three main differences between RNA and DNA: The sugar in RNA is ribose instead of deoxyribose. RNA is generally single-stranded. RNA contains uracil in place of thymine. Copyright Pearson Prentice Hall

Research What are the 3 types of RNA? Copyright Pearson Prentice Hall

Types of RNA Types of RNA There are three main types of RNA: messenger RNA ribosomal RNA transfer RNA Copyright Pearson Prentice Hall

Types of RNA The three main types of RNA are messenger RNA, ribosomal RNA, and transfer RNA. Messenger RNA (mRNA) carries copies of instructions for assembling amino acids into proteins. ***Serve as “messengers” from DNA to the rest of the cell Copyright Pearson Prentice Hall

Types of RNA The three main types of RNA are messenger RNA, ribosomal RNA, and transfer RNA. Ribosomal RNA is combined with proteins to form ribosomes. Ribosomes are made up of proteins and ribosomal RNA (rRNA). Copyright Pearson Prentice Hall

Types of RNA During protein construction, transfer RNA (tRNA) transfers each amino acid to the ribosome. The three main types of RNA are messenger RNA, ribosomal RNA, and transfer RNA. Copyright Pearson Prentice Hall

Research Describe Transcription. Copyright Pearson Prentice Hall

Transcription DNA is copied in the form of a complementary sequence called RNA Requires RNA polymerase to bind to DNA and separate the DNA strands as a template to assemble the nucleotides into another DNA strand This first process is called transcription. The process begins at a section of DNA called a promoter, which has specific base sequence that signal where to start Copyright Pearson Prentice Hall

Protein Synthesis DNA molecule DNA strand (template) 3¢ 5¢
TRANSCRIPTION mRNA 5¢ 3¢ Codon TRANSLATION Protein Amino acid

Transcription RNA RNA polymerase DNA During transcription, RNA polymerase uses one strand of DNA as a template to assemble nucleotides into a strand of RNA. Copyright Pearson Prentice Hall

Research What are the functions of introns and exons?

RNA Editing RNA Editing Some DNA within a gene is not needed to produce or code for a protein. These areas are called introns. The DNA sequences that code for proteins are called exons. Copyright Pearson Prentice Hall

RNA Editing The introns are cut out of RNA molecules…scientist have no idea why… The exons are the spliced together to form mRNA. Exon Intron DNA Pre-mRNA mRNA Many RNA molecules have sections, called introns, edited out of them before they become functional. The remaining pieces, called exons, are spliced together. Then, a cap and tail are added to form the final RNA molecule. Cap Tail Copyright Pearson Prentice Hall

Bell Work Compare the DNA code to something you need a code to in your daily life. What are the 3 types of RNA? Explain transcription. Learning Target I can explain the genetic code.

Learning Target I can explain the genetic code. Agenda Bell Work / LT Plickers Discussion Activity

Research What is the genetic code?

The Genetic Code The Genetic Code The genetic code is the “language” of mRNA instructions. The code is written using four “letters” (the bases: A, U, C, and G). Copyright Pearson Prentice Hall

Research What is a codon?

The Genetic Code A codon consists of three consecutive nucleotides on mRNA that specify a particular amino acid. A codon is a group of three nucleotides on messenger RNA that specify a particular amino acid. Copyright Pearson Prentice Hall

The Genetic Code There are 64 possible base codons…
The genetic code shows the amino acid to which each of the 64 possible codons corresponds. To decode a codon, start at the middle of the circle and move outward. Copyright Pearson Prentice Hall

Research What is translation and where does it take place?

Translation Translation Translation is the decoding of an mRNA message into a polypeptide chain (protein). Translation takes place on ribosomes. During translation, the cell uses information from messenger RNA to produce proteins and tell what order they should be listed in on the polypeptide. Nucleus Copyright Pearson Prentice Hall mRNA

Translation The ribosome binds new tRNA molecules and amino acids as it moves along the mRNA. Lysine Phenylalanine tRNA Methionine Ribosome During translation, or protein synthesis, the cell uses information from messenger RNA to produce proteins. The cell uses all three main forms of RNA during this process. mRNA Start codon Copyright Pearson Prentice Hall

Translation Lysine tRNA Protein Synthesis During translation, or protein synthesis, the cell uses information from messenger RNA to produce proteins. The cell uses all three main forms of RNA during this process. mRNA Translation direction Copyright Pearson Prentice Hall Ribosome

Translation The process continues until the ribosome reaches a stop codon. Polypeptide Ribosome tRNA During translation, or protein synthesis, the cell uses information from messenger RNA to produce proteins. The cell uses all three main forms of RNA during this process. Copyright Pearson Prentice Hall mRNA

Amino acids within a polypeptide
Codon Codon Codon Genes and Proteins DNA mRNA Protein Single strand of DNA Codon Codon Codon mRNA This diagram illustrates how information for specifying the traits of an organism is carried in DNA. The sequence of bases in DNA is used as a template for mRNA. The codons of mRNA specify the sequence of amino acids in a protein, and proteins play a key role in producing an organism’s traits. Alanine Arginine Leucine Amino acids within a polypeptide Copyright Pearson Prentice Hall

Bell Work 4-23-2015 Are enzymes tossed away or reused?
Log onto Quizlet and Study for Friday’s Vocabulary Formative. Learning Target I can explain DNA structure and Replication.

Learning Target I can explain DNA structure and Replication. Agenda Bell Work / LT Quizlet Activity Plickers

Bell Work 4-24-2015 Log onto Quizlet and study for Formative.
Learning Target I can earn a “3” on the review formative. Agenda Bell Work / LT Formative Activity

DNA Replication Enzyme Wrap Up

Bell Work 4-27-2015 Study for Formative. Learning Target
I can earn a “3” on the Formative because I studied. Agenda Bell Work / LT Formative Research

Research What are mutations?
Define: gene mutations, chromosomal mutations, polyploidy Find and define the 2 Types of gene mutations. Find examples of deletions, substitutions, translocations, insertions, inversions How are genes regulated? What are lac and hox genes? How are lac genes turned off and on? Define operon, operator, and differentiation. How are eukaryotic genes regulated?

12–3 The role of a master plan in a building is similar to the role of which molecule? messenger RNA DNA transfer RNA ribosomal RNA Copyright Pearson Prentice Hall

12–3 A base that is present in RNA but NOT in DNA is thymine. uracil. cytosine. adenine. Copyright Pearson Prentice Hall

12–3 The nucleic acid responsible for bringing individual amino acids to the ribosome is transfer RNA. DNA. messenger RNA. ribosomal RNA. Copyright Pearson Prentice Hall

12–3 A region of a DNA molecule that indicates to an enzyme where to bind to make RNA is the intron. exon. promoter. codon. Copyright Pearson Prentice Hall

12–3 A codon typically carries sufficient information to specify a(an) single base pair in RNA. single amino acid. entire protein. single base pair in DNA. Copyright Pearson Prentice Hall

12–4 Mutations Copyright Pearson Prentice Hall

Bell work 4-28-2015 1. How can you study for the EOC?
Refer to the EOC Cheat Sheet for #1-2: 2. Which of the following chemical formulas represent an organic molecule? A. H2O B. AgNO C. C12H22O11 3. Which of the following solutions has the greatest concentration of hydroxide ions? A. Urine (pH 6) B. Rainwater (pH 5.5) C. Gastric juice (pH 2.0) 4. What is translation and where does it take place? 5. What is transcription and where does it take place? Learning Target I can explain genetic mutations and how genes regulate themselves.

Learning Target I can explain genetic mutations and how genes regulate themselves. Agenda Bell Work Discussion Activity

Research What are mutations?

Mutations are changes in the genetic material.

Gene mutations - Mutations that produce changes in a single gene
Kinds of Mutations Kinds of Mutations Gene mutations - Mutations that produce changes in a single gene Chromosomal mutations - Mutations that produce changes in whole chromosomes Copyright Pearson Prentice Hall

involve a change in one or a few nucleotides known as point mutations
Kinds of Mutations Gene Mutations involve a change in one or a few nucleotides known as point mutations they occur at a single point in the DNA sequence. Point mutations include substitutions, insertions, and deletions. Copyright Pearson Prentice Hall

usually affect no more than a single amino acid
Kinds of Mutations Substitutions usually affect no more than a single amino acid a base is changed Gene mutations result from changes in a single gene. In a substitution, one base replaces another. Copyright Pearson Prentice Hall

- The effects of insertions or deletions are more dramatic.
Kinds of Mutations Frameshift mutations - The effects of insertions or deletions are more dramatic. - addition or deletion of a nucleotide causes a shift in the grouping of codons. Copyright Pearson Prentice Hall

In an insertion, an extra base is inserted into a base sequence.
Kinds of Mutations In an insertion, an extra base is inserted into a base sequence. Gene mutations result from changes in a single gene. In an insertion, an extra base is inserted into a base sequence. Copyright Pearson Prentice Hall

Kinds of Mutations In a deletion, the loss of a single base is deleted and the reading frame is shifted. Gene mutations result from changes in a single gene. The loss of a single letter in a sentence models the effects of the deletion of one base in a DNA sequence. Copyright Pearson Prentice Hall

Chromosomal Mutations
Kinds of Mutations Chromosomal Mutations - involve changes in the number or structure of chromosomes. - include deletions, duplications, inversions, and translocations. Copyright Pearson Prentice Hall

Deletions involve the loss of all or part of a chromosome.
Kinds of Mutations Deletions involve the loss of all or part of a chromosome. Chromosomal mutations involve changes in whole chromosomes. Copyright Pearson Prentice Hall

Kinds of Mutations Duplications produce extra copies of parts of a chromosome. Chromosomal mutations involve changes in whole chromosomes. Copyright Pearson Prentice Hall

Inversions reverse the direction of parts of chromosomes.
Kinds of Mutations Inversions reverse the direction of parts of chromosomes. Chromosomal mutations involve changes in whole chromosomes. Copyright Pearson Prentice Hall

Kinds of Mutations Translocations occurs when part of one chromosome breaks off and attaches to another. Chromosomal mutations involve changes in whole chromosomes. Copyright Pearson Prentice Hall

Significance of Mutations
Many mutations have little or no effect on gene expression. Some mutations are the cause of genetic disorders. Polyploidy is the condition in which an organism has extra sets of chromosomes. Copyright Pearson Prentice Hall

12–4 A mutation in which all or part of a chromosome is lost is called a(an) duplication. deletion. inversion. point mutation. Copyright Pearson Prentice Hall

12–4 A mutation that affects every amino acid following an insertion or deletion is called a(an) frameshift mutation. point mutation. chromosomal mutation. inversion. Copyright Pearson Prentice Hall

12–4 A mutation in which a segment of a chromosome is repeated is called a(an) deletion. inversion. duplication. point mutation. Copyright Pearson Prentice Hall

12–4 The type of point mutation that usually affects only a single amino acid is called a deletion. a frameshift mutation. an insertion. a substitution. Copyright Pearson Prentice Hall

12–4 When two different chromosomes exchange some of their material, the mutation is called a(an) inversion. deletion. substitution. translocation. Copyright Pearson Prentice Hall

12-5 Gene Regulation

Gene Regulation: An Example
E. coli provides an example of how gene expression can be regulated. An operon is a group of genes that operate together. In E. coli, these genes must be turned on so the bacterium can use lactose as food. they are called the lac operon.

How are lac genes turned off and on?

lac genes are turned off by repressors turned on by the presence of lactose.

On one side of the operon's three genes are two regulatory regions. In the promoter (P) region, RNA polymerase binds and then begins transcription. The lac genes in E. coli are turned off by repressors and turned on by the presence of lactose. When lactose is not present, the repressor binds to the operator region, preventing RNA polymerase from beginning transcription. Lactose causes the repressor to be released from the operator region.

The other region is the operator (O). The lac genes in E. coli are turned off by repressors and turned on by the presence of lactose. When lactose is not present, the repressor binds to the operator region, preventing RNA polymerase from beginning transcription. Lactose causes the repressor to be released from the operator region.

When the lac repressor binds to the O region, transcription is not possible. The lac genes in E. coli are turned off by repressors and turned on by the presence of lactose. When lactose is not present, the repressor binds to the operator region, preventing RNA polymerase from beginning transcription. Lactose causes the repressor to be released from the operator region. Copyright Pearson Prentice Hall

When lactose is added, sugar binds to the repressor proteins. The lac genes in E. coli are turned off by repressors and turned on by the presence of lactose. When lactose is not present, the repressor binds to the operator region, preventing RNA polymerase from beginning transcription. Lactose causes the repressor to be released from the operator region. Copyright Pearson Prentice Hall

The repressor protein changes shape and falls off the operator and transcription is made possible. The lac genes in E. coli are turned off by repressors and turned on by the presence of lactose. When lactose is not present, the repressor binds to the operator region, preventing RNA polymerase from beginning transcription. Lactose causes the repressor to be released from the operator region. Copyright Pearson Prentice Hall

Many genes are regulated by repressor proteins. Some genes use proteins that speed transcription. Sometimes regulation occurs at the level of protein synthesis.

Eukaryotic Gene Regulation
How are most eukaryotic genes controlled?

Operons are generally not found in eukaryotes. Most eukaryotic genes are controlled individually and have regulatory sequences that are much more complex than those of the lac operon.

Many eukaryotic genes have a sequence called the TATA box. Many eukaryotic genes include a sequence called the TATA box that may help position RNA polymerase. Eukaryotic genes have regulatory sequences that are more complex than prokaryotic genes. Direction of transcription

The TATA box seems to help position RNA polymerase. Many eukaryotic genes include a sequence called the TATA box that may help position RNA polymerase. Eukaryotic genes have regulatory sequences that are more complex than prokaryotic genes. Direction of transcription

Eukaryotic promoters are usually found just before the TATA box, and consist of short DNA sequences. Many eukaryotic genes include a sequence called the TATA box that may help position RNA polymerase. Eukaryotic genes have regulatory sequences that are more complex than prokaryotic genes. Direction of transcription

Genes are regulated in a variety of ways by enhancer sequences. Many proteins can bind to different enhancer sequences. Some DNA-binding proteins enhance transcription by: opening up tightly packed chromatin helping to attract RNA polymerase blocking access to genes.

Development and Differentiation
As cells grow and divide, they undergo differentiation, meaning they become specialized in structure and function. Hox genes control the differentiation of cells and tissues in the embryo.

Careful control of expression in hox genes is essential for normal development. All hox genes are descended from the genes of common ancestors.

Hox Genes Fruit fly chromosome Mouse chromosomes Fruit fly embryo Mouse embryo n fruit flies, a series of hox genes along a chromosome determines the basic structure of the fly’s body. Mice have very similar genes on four different chromosomes. The color bars along the mouse’s back show the approximate body area affected by genes of the corresponding colors. Copyright Pearson Prentice Hall Adult fruit fly Adult mouse

12–5 Which sequence shows the typical organization of a single gene site on a DNA strand? start codon, regulatory site, promoter, stop codon regulatory site, promoter, start codon, stop codon start codon, promoter, regulatory site, stop codon promoter, regulatory site, start codon, stop codon Copyright Pearson Prentice Hall

12–5 A group of genes that operates together is a(an) promoter.
operon. operator. intron. Copyright Pearson Prentice Hall

12–5 Repressors function to turn genes off. produce lactose.
turn genes on. slow cell division. Copyright Pearson Prentice Hall

12–5 Which of the following is unique to the regulation of eukaryotic genes? promoter sequences TATA box different start codons regulatory proteins Copyright Pearson Prentice Hall

12–5 Organs and tissues that develop in various parts of embryos are controlled by regulation sites. RNA polymerase. hox genes. DNA polymerase. Copyright Pearson Prentice Hall

Biology Copyright Pearson Prentice Hall.

Similar presentations

Presentation on theme: "Biology Copyright Pearson Prentice Hall."— Presentation transcript:

Similar presentations

About project

Feedback

Log in

Auth with social network:

Biology Copyright Pearson Prentice Hall.

Similar presentations

Presentation on theme: "Biology Copyright Pearson Prentice Hall."— Presentation transcript:

Similar presentations

About project

Feedback