biology copyright pearson prentice hall. 12–1 dna copyright pearson prentice hall
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Biology
Copyright Pearson Prentice Hall
12–1 DNA
Copyright Pearson Prentice Hall
Bell Work 4-20-20151. What is the control center of a cell?
2. 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:
1.Bell Work / LT
2.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
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 and Transformation
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 and Transformation
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.
Second experiment?
Griffith and Transformation
Experiment 2: Mice were injected with the harmless strain of bacteria. These mice didn’t get sick.
Harmless bacteria (rough colonies)
Lives
Third experiment?
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Griffith and Transformation
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)
Lives
Fourth experiment?
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Griffith and Transformation
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.
What did Griffith conclude?
Griffith and Transformation
Griffith concluded that the heat-killed bacteria passed their disease-causing ability to the harmless strain.
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What did Griffith call this process of changing one molecule into another?
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Griffith and Transformation
Transformation
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.
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What did Avery want to determine?
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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.
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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?
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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 ExperimentThe Hershey-Chase Experiment
Alfred Hershey and Martha Chase studied viruses—nonliving particles smaller than a cell that can infect living organisms.
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The Hershey-Chase Experiment
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.
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How did they go about their experiment?
The Hershey-Chase Experiment
They grew viruses in cultures containing radioactive isotopes of phosphorus-32 (32P) and sulfur-35 (35S).
The Hershey-Chase Experiment
If 35S was found in the bacteria, it would mean that the viruses’ protein had been injected into the bacteria.
Bacteriophage withsuffur-35 in protein coat
Phage infects bacterium
No radioactivity inside bacterium
The Hershey-Chase Experiment
If 32P was found in the bacteria, then it was the DNA that had been injected.
Bacteriophage withphosphorus-32 in DNA
Phage infects bacterium
Radioactivity inside bacterium
What did they find in the bacteria?
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The Hershey-Chase Experiment
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
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
The Components and Structure of DNA
There are four kinds of bases in in DNA:
adenineguanine cytosinethymine
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The Components and Structure of DNA
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.
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The Components and Structure of DNA
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.
The Components and Structure of DNA
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.
The Components and Structure of DNADNA Double Helix
The Components and Structure of DNA
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 4-21-20151. What does a double helix look like?
2. 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
1.Bell Work / LT
2.Plickers
3.Activity
4.Discussion
Bell Work 4-22-2015
1. What does a double helix look like?
2. What is the pattern for base pairing?
3. Name the molecules that make up the sides of the DNA Ladder.
Learning Target
I can explain the structure of a double helix.
Learning Target
I can explain the structure of a double helix.
Agenda
1.Bell Work / LT
2.Review Assignment
3.Activity
4.Plickers
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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.
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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.
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12–1
DNA is a long molecule made of monomers called
nucleotides.
purines.
pyrimidines.
sugars.
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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.
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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.
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12-2 Chromosomes and DNA Replication
Bell Work 4-21-2015
1. Considering your knowledge of DNA, what might happen if bases paired incorrectly?
2. What is the pattern for base pairing?
3. 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
1.Bell Work / LT
2.Discussion of RNA
3.Assignment
4.Quizlet
Research
Where is DNA found in both prokaryotic and eukaryotic cells?
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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.
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DNA and Chromosomes
Chromosome
E. Coli Bacterium
Bases on the Chromosomes
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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.
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DNA and Chromosomes
Chromosome StructureEukaryotic 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.
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DNA and Chromosomes
Eukaryotic Chromosome Structure
Chromosome
Supercoils
Nucleosome
DNA double helix
Histones
Coils
Research
What is DNA Replication?
https://www.youtube.com/watch?v=27TxKoFU2Nw
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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.
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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.
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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.
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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.
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DNA Replication
Nitrogen Bases
Replication Fork
DNA Polymerase
Replication Fork
Original strandNew Strand
Growth
Growth
Research
How does replication occur?
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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.
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DNA Replication
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.
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12–2
In prokaryotic cells, DNA is found in the
cytoplasm.
nucleus.
ribosome.
cell membrane.
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12–2
The first step in DNA replication is
producing two new strands.
separating the strands.
producing DNA polymerase.
correctly pairing bases.
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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
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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.
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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.
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12-3 RNA and Protein Synthesis12–3 RNA and Protein Synthesis
Bell Work 4-21-2015
1. What might you compare the looks of a supercoiled nucleosome to that you are familiar?
2. What is chromatin?
3. 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
1.Bell Work / LT
2.Discussion of RNA
3.Activity / Assignment
4.Plickers
5.Quizlet
Research
How does a gene Work?
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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.
Research
What is the structure of RNA compare to DNA?
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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.
Research
What are the 3 types of RNA?
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Types of RNA
Types of RNA
There are three main types of RNA:messenger RNAribosomal RNAtransfer RNA
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Types of 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
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Types of RNA
Ribosomes are made up of proteins and ribosomal RNA (rRNA).
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Types of RNA
During protein construction, transfer RNA (tRNA) transfers each amino acid to the ribosome.
Research
Describe Transcription.
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TranscriptionDNA 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
Protein Synthesis
DNADNAmoleculemolecule
DNA strandDNA strand(template)(template)
33
TRANSCRIPTIONTRANSCRIPTION
CodonCodon
mRNAmRNA
TRANSLATIONTRANSLATION
ProteinProtein
Amino acidAmino acid
3355
55
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Transcription
RNA
RNA polymerase
DNA
Research
What are the functions of introns and exons?
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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.
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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 IntronDNA
Pre-mRNA
mRNA
Cap Tail
Bell Work 4-22-2015
1. Compare the DNA code to something you need a code to in your daily life.
2. What are the 3 types of RNA?
3. Explain transcription.
Learning Target
I can explain the genetic code.
Learning Target
I can explain the genetic code.
Agenda
1.Bell Work / LT
2.Plickers
3.Discussion
4.Activity
Research
What is the genetic code?
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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).
Research
What is a codon?
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The Genetic Code
A codon consists of three consecutive nucleotides on mRNA that specify a particular amino acid.
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The Genetic Code
There are 64 possible base codons…
Research
What is translation and where does it take place?
Nucleus
mRNACopyright Pearson Prentice Hall
TranslationTranslation
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.
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Translation
LysinetRNAPhenylalanine
Methionine
Ribosome
mRNAStart codon
The ribosome binds new tRNA molecules and amino acids as it moves along the mRNA.
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Translation
Protein Synthesis
tRNA
Ribosome
mRNA
Lysine
Translation direction
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Translation
The process continues until the ribosome reaches a stop codon.
Polypeptide
Ribosome
tRNA
mRNA
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Genes and Proteins
DNA
mRNA
Protein
CodonCodon Codon
Codon Codon Codon
mRNA
Alanine Arginine Leucine
Amino acids within a polypeptide
Single strand of DNA
Bell Work 4-23-20151. Are enzymes tossed away or reused?
2. 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
1.Bell Work / LT
2.Quizlet
3.Activity
4.Plickers
Bell Work 4-24-20151. Log onto Quizlet and study for Formative.
Learning Target
I can earn a “3” on the review formative.
Agenda
1. Bell Work / LT
2. Formative
3. Activity
DNA Replication Enzyme Wrap Up
Bell Work 4-27-20151. Study for Formative.
Learning Target
I can earn a “3” on the Formative because I studied.
Agenda
1. Bell Work / LT
2. Formative
3. Research
Research1. What are mutations?
2. Define: gene mutations, chromosomal mutations, polyploidy
3. Find and define the 2 Types of gene mutations.
4. Find examples of deletions, substitutions, translocations, insertions, inversions
5. How are genes regulated?
6. What are lac and hox genes?
7. How are lac genes turned off and on?
8. Define operon, operator, and differentiation.
9. How are eukaryotic genes regulated?
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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
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12–3
A base that is present in RNA but NOT in DNA is
thymine.
uracil.
cytosine.
adenine.
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12–3
The nucleic acid responsible for bringing individual amino acids to the ribosome is
transfer RNA.
DNA.
messenger RNA.
ribosomal RNA.
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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.
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.
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12–3
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12–4 Mutations
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. AgNO3 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
1.Bell Work
2.Discussion
3.Activity
Research
What are mutations?
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12-4 Mutations
Mutations are changes in the genetic material.
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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
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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.
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Kinds of Mutations
Substitutions
-usually affect no more than a single amino acid
-a base is changed
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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.
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Kinds of Mutations
In an insertion, an extra base is inserted into a base sequence.
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Kinds of Mutations
In a deletion, the loss of a single base is deleted and the reading frame is shifted.
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Kinds of Mutations
Chromosomal Mutations
- involve changes in the number or structure of chromosomes.
- include deletions, duplications, inversions, and translocations.
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Kinds of Mutations
Deletions involve the loss of all or part of a chromosome.
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Kinds of Mutations
Duplications produce extra copies of parts of a chromosome.
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Kinds of Mutations
Inversions reverse the direction of parts of chromosomes.
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Kinds of Mutations
Translocations occurs when part of one chromosome breaks off and attaches to another.
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Significance of Mutations
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.
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12–4
A mutation in which all or part of a chromosome is lost is called a(an)
duplication.
deletion.
inversion.
point mutation.
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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.
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12–4
A mutation in which a segment of a chromosome is repeated is called a(an)
deletion.
inversion.
duplication.
point mutation.
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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.
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12–4
When two different chromosomes exchange some of their material, the mutation is called a(an)
inversion.
deletion.
substitution.
translocation.
12-5 Gene Regulation
Gene Regulation: An Example
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.
Gene Regulation: An Example
How are lac genes turned off and on?
Gene Regulation: An Example
lac genes are turned off by repressors turned on by the presence of lactose.
Gene Regulation: An Example 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.
Gene Regulation: An Example
The other region is the operator (O).
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Gene Regulation: An Example
When the lac repressor binds to the O region, transcription is not possible.
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Gene Regulation: An Example When lactose is added, sugar binds to the repressor proteins.
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Gene Regulation: An Example The repressor protein changes shape and falls off the operator and
transcription is made possible.
Gene Regulation: An Example
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?
Eukaryotic Gene Regulation
Eukaryotic Gene Regulation
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.
Eukaryotic Gene Regulation
Many eukaryotic genes have a sequence called the TATA box.
Direction of transcription
Eukaryotic Gene Regulation
The TATA box seems to help position RNA polymerase.
Direction of transcription
Eukaryotic Gene Regulation
Eukaryotic promoters are usually found just before the TATA box, and consist of short DNA sequences.
Direction of transcription
Eukaryotic Gene Regulation
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
Development and DifferentiationAs 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.
Development and Differentiation
Careful control of expression in hox genes is essential for normal development.
All hox genes are descended from the genes of common ancestors.
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Development and Differentiation
Hox Genes
Fruit fly chromosome
Fruit fly embryo
Adult fruit fly
Mouse chromosomes
Mouse embryo
Adult mouse
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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
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12–5
A group of genes that operates together is a(an)
promoter.
operon.
operator.
intron.
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12–5
Repressors function to
turn genes off.
produce lactose.
turn genes on.
slow cell division.
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12–5
Which of the following is unique to the regulation of eukaryotic genes?
promoter sequences
TATA box
different start codons
regulatory proteins
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12–5
Organs and tissues that develop in various parts of embryos are controlled by
regulation sites.
RNA polymerase.
hox genes.
DNA polymerase.