Click on a lesson name to select. FROM DNA TO PROTEINS Section 1: DNA: The Genetic Material Section 2: Replication of DNA Section 3: DNA, RNA, and Protein Section 4: Gene Regulation and Mutation
Jan 29, 2016
Click on a lesson name to select.
FROM DNA TO PROTEINS
Section 1: DNA: The Genetic Material
Section 2: Replication of DNA
Section 3: DNA, RNA, and Protein
Section 4: Gene Regulation and Mutation
DNA: The Genetic Material
Section 1
Griffith Performed the first major experiment that led to
the discovery of DNA as the genetic material
Avery
Identified the molecule that transformed the R strain of bacteria into the S strain
Concluded that when the S cells were killed, DNA was released
R bacteria incorporated this DNA into their cells and changed into S cells.
DNA: The Genetic Material
Section 1
Hershey and Chase
Used radioactive labeling to trace the DNA and protein
Concluded that the viral DNA was injected into the cell and provided the genetic information needed to produce new viruses
DNA: The Genetic Material
Section 1
DNA Structure Nucleotides
Consist of a five-carbon sugar, a phosphate group, and a nitrogenous base
DNA: The Genetic Material
Section 1
Chargaff
Chargaff’s rule: C = G and T = A
DNA: The Genetic Material
Section 1
X-ray Diffraction
X-ray diffraction data helped solve the structure of DNA
Indicated that DNA was a double helix
DNA: The Genetic Material
Section 1
Watson and Crick
Built a model of the double helix that conformed to the others’ research
1. two outside strands consist of alternating deoxyribose and phosphate 2. cytosine and guanine bases pair to each other by three hydrogen bonds 3. thymine and adenine bases pair to each other by two hydrogen bonds
DNA: The Genetic Material
Section 1
Molecular Genetics
DNA Structure
DNA often is compared to a twisted ladder.
Rails of the ladder are represented by the alternating deoxyribose and phosphate.
The pairs of bases (cytosine–guanine or thymine–adenine) form the steps.
DNA: The Genetic Material
Section 1
Orientation
On the top rail, the strand is said to be oriented 5′ to 3′.
The strand on the bottom runs in the opposite direction and is oriented 3′ to 5′.
DNA: The Genetic Material
Section 1
DNA: The Genetic Material
Chromosome Structure DNA coils around histones to form nucleosomes,
which coil to form chromatin fibers. The chromatin fibers supercoil to form chromosomes
that are visible in the metaphase stage of mitosis.
Section 1
Replication of DNA
Semiconservative Replication
Parental strands of DNA separate, serve as templates, and produce DNA molecules that have one strand of parental DNA andone strand of new DNA.
Section 2
Unwinding
DNA helicase, an enzyme, is responsible for unwinding and unzipping the double helix.
RNA primase adds a short segment of RNA, called an RNA primer, on each DNA strand.
Replication of DNA
Section 2
Base pairing
DNA polymerase continues adding appropriate nucleotides to the chain by adding to the 3′ end of the new DNA strand.
Replication of DNA
Section 2
One strand is called the leading strand and is elongated as the DNA unwinds.
The other strand of DNA, called the lagging strand, elongates away from the replication fork.
The lagging strand is synthesized discontinuously into small segments, called Okazaki fragments.
Replication of DNA
Section 2
Joining
DNA polymerase removes the RNA primer and fills in the place with DNA nucleotides.
DNA ligase links the two sections.
Replication of DNA
Section 2
Replication of DNA
Comparing DNA Replication in Eukaryotes and Prokaryotes
Eukaryotic DNA unwinds in multiple areas as DNA is replicated.
In prokaryotes, the circular DNA strand is opened at one origin of replication.
Section 2
DNA, RNA, and Protein
Central Dogma – Information flows in one dirrection, from DNA to RNA(Francis Crick) RNA
Contains the sugar ribose and the base uracil instead of thymine
Usually is single stranded
Section 3
Messenger RNA (mRNA) Long strands of RNA nucleotides that are
formed complementary to one strand of DNA
Ribosomal RNA (rRNA) Associates with proteins to form ribosomes
in the cytoplasm
Transfer RNA (tRNA) Smaller segments of RNA nucleotides that
transport amino acids to the ribosome
DNA, RNA, and Protein
Section 3
DNA is unzipped in the nucleus and RNA polymerase binds to a specific section where an mRNA will be synthesized.
Transcription
Through transcription, the DNA code is transferred to mRNA in the nucleus.
DNA, RNA, and Protein
Section 3
RNA Processing
The code on the DNA is interrupted periodically by sequences that are not in the final mRNA.
Intervening sequences are called introns.
Remaining pieces of DNA that serve as the coding sequences are called exons.
DNA, RNA, and Protein
Section 3
The Code
Experiments during the 1960s demonstrated that the DNA code was a three-base code.
The three-base code in DNA or mRNA is called a codon.
DNA, RNA, and Protein
Section 3
Translation In translation, tRNA
molecules act as the interpreters of the mRNA codon sequence.
At the middle of the folded strand, there is a three-base coding sequence called the anticodon.
Each anticodon is complementary to a codon on the mRNA.
DNA, RNA, and Protein
Section 3
DNA, RNA, and Protein
Section 3
DNA, RNA, and Protein
One Gene—One Enzyme
The Beadle and Tatum experiment showed that one gene codes for one enzyme. We now know that one gene codes for one polypeptide.
Section 3
Gene Regulation and Mutation
Prokaryote Gene Regulation Ability of an organism to control which genes
are transcribed in response to the environment An operon is a section of DNA that contains
the genes for the proteins needed for a specific metabolic pathway.
Operator Promoter Regulatory gene Genes coding for proteins
Section 4
The Trp Operon
Gene Regulation and Mutation
Section 4
The Lac Operon
Gene Regulation and Mutation
Section 4
Eukaryote Gene Regulation
Controlling transcription
Transcription factors ensure that a gene is used at the right time and that proteins are made in the right amounts
The complex structure of eukaryotic DNA also regulates transcription.
Gene Regulation and Mutation
Section 4
RNA Interference
RNA interference can stop the mRNA from translating its message.
Gene Regulation and Mutation
Section 4
Mutations
A permanent change that occurs in a cell’s DNA is called a mutation.
Types of mutations
Point mutation Insertion Deletion
Gene Regulation and Mutation
Section 4
Gene Regulation and Mutation
Section 4
Protein Folding and Stability
Substitutions also can lead to genetic disorders.
Can change both the folding and stability of the protein
Gene Regulation and Mutation
Section 4
Causes of Mutation
Can occur spontaneously
Chemicals and radiation also can damage DNA.
High-energy forms of radiation, such as X rays and gamma rays, are highly mutagenic.
Gene Regulation and Mutation
Section 4
Body-cell v. Sex-cell Mutation
Somatic cell mutations are not passed on to the next generation.
Mutations that occur in sex cells are passed on to the organism’s offspring and will be present in every cell of the offspring.
Gene Regulation and Mutation
Section 4
1. A2. B3. C4. D
CDQ 1
A. Watson and Crick
B. Mendel
C. Hershey and Chase
D. Avery
Which scientist(s) definitively proved that DNA transfers genetic material?
Molecular Genetics
Chapter Diagnostic Questions
Chapter
1. A2. B3. C4. D
CDQ 2
Molecular Genetics
Chapter Diagnostic Questions
Chapter
A. ligase
B. Okazaki fragments
C. micro RNA
D. helicase
Name the small segments of the lagging DNA strand.
1. A2. B3. C4. D
CDQ 3
Molecular Genetics
Chapter Diagnostic Questions
Chapter
A. It contains the sugar ribose.
B. It contains the base uracil.
C. It is single-stranded.
D. It contains a phosphate.
Which is not true of RNA?
1. A2. B3. C4. D
FQ 1
Molecular GeneticsChapter
A. carbohydrate
B. DNA
C. lipid
D. protein
The experiments of Avery, Hershey and Chase provided evidence that the carrier of genetic information is _______.
Section 1 Formative Questions
1. A2. B3. C4. D
FQ 2
Molecular GeneticsChapter
A. A—G and C—T
B. A—T and C—G
C. C—A and G—T
D. C—U and A—G
What is the base-pairing rule for purines and pyrimidines in the DNA molecule?
Section 1 Formative Questions
1. A2. B3. C4. D
FQ 3
Molecular GeneticsChapter
Section 1 Formative Questions
A.chromatin and histones
B. DNA and protein
C. DNA and lipids
D. protein and centromeres
What are chromosomes composed of?
1. A
2. B
FQ 4
Molecular GeneticsChapter
The work of Watson and Crick solved the mystery of how DNA works as a genetic code.
A. TrueB. False
Section 2 Formative Questions
1. A2. B3. C4. D
FQ 5
Molecular GeneticsChapter
Section 2 Formative Questions
A. DNA ligase
B. DNA polymerase
C. hilicase
D. RNA primer
Which is not an enzyme involved in DNA replication?
1. A2. B3. C4. D
FQ 6
Molecular GeneticsChapter
Which shows the basic chain of events in all organisms for reading and expressing genes?
A. DNA RNA protein
B. RNA DNA protein
C. mRNA rRNA tRNA
D. RNA processing transcription translation
Section 3 Formative Questions
1. A2. B3. C4. D
FQ 7
Molecular GeneticsChapter
Section 3 Formative Questions
In the RNA molecule, uracil replaces _______.
A. adenine
B. cytosine
C. purine
D. thymine
1. A2. B3. C4. D
FQ 8
Molecular GeneticsChapter
Section 3 Formative Questions
Which diagram shows messenger RNA (mRNA)?
A.
C.
B.
D.
1. A2. B3. C4. D
FQ 9
Molecular GeneticsChapter
Section 3 Formative Questions
What characteristic of the mRNA molecule do scientists not yet understand?
A. intervening sequences in the mRNA molecule called introns
B. the original mRNA made in the nucleus called the pre-mRNA
C. how the sequence of bases in the mRNA molecule codes for amino acids
D. the function of many adenine nucleotides at the 5′ end called the poly-A tail
1. A2. B3. C4. D
FQ 10
Molecular GeneticsChapter
Why do eukaryotic cells need a complex control system to regulate the expression of genes?
A. All of an organism’s cells transcribe the same genes.
B. Expression of incorrect genes can lead to mutations.
C. Certain genes are expressed more frequently than others are.
D. Different genes are expressed at different times in an
organism’s lifetime.
Section 4 Formative Questions
1. A2. B3. C4. D
FQ 11
Molecular GeneticsChapter
Section 4 Formative Questions
Which type of gene causes cells to become specialized in structure in function?
A. exon
B. Hox gene
C. intron
D. operon
1. A2. B3. C4. D
FQ 12
Molecular GeneticsChapter
Section 4 Formative Questions
What is an immediate result of a mutation in a gene?
A. cancer
B. genetic disorder
C. nonfunctional enzyme
D. amino acid deficiency
1. A2. B3. C4. D
FQ 13
Molecular GeneticsChapter
Section 4 Formative Questions
Which is the most highly mutagenic?
A. chemicals in food
B. cigarette smoke
C. ultraviolet radiation
D. X rays
1. A2. B3. C4. D
CAQ 1
Molecular GeneticsChapter
Look at the following figure. Identify the proteins that DNA first coils around.
Chapter Assessment Questions
A. chromatin fibers
B. chromosomes
C. histones
D. nucleosome
Explain the difference between body-cell and sex-cell mutation.
Molecular Genetics
Chapter Assessment Questions
Chapter
Answer: A mutagen in a body cell becomespart of the of the genetic sequence in that cell and in future daughter cells. The cell may die or simply not perform its normal function. These mutations are not passed on to the next generation. When mutations occur in sex cells, they will be present in every cell of the offspring.
CAQ 3
1. A2. B3. C4. D
STP 1
Molecular GeneticsChapter
What does this diagram show about the replication of DNA in eukaryotic cells?
Standardized Test Practice
A. DNA is replicated only at certain places along the chromosome.
B. DNA replication is both semicontinuous and conservative.
C. Multiple areas of replication occur along the chromosome at the same time.
D. The leading DNA strand is synthesized discontinuously.
1. A2. B3. C4. D
STP 2
Molecular GeneticsChapter
Standardized Test Practice
A. mRNA processing
B. protein synthesis
C. transcription
D. translation
What is this process called?
1. A2. B3. C4. D
STP 3
Molecular GeneticsChapter
Standardized Test Practice
What type of mutation results in this change in the DNA sequence?
A. deletion
B. frameshift
C. insertion
D. substitution
TTCAGG TTCTGG
1. A2. B3. C4. D
STP 4
Molecular GeneticsChapter
Standardized Test Practice
How could RNA interference be used to treat diseases such as cancer and diabetes?
A. by activating genes to produce proteins that can overcome the disease
B. by interfering with DNA replication in cells affected by the disease
C. by preventing the translation of mRNA into the genes associated with the disease
D. by shutting down protein synthesis in the cells of diseased tissues
1. A
2. B
STP 5
Molecular GeneticsChapter
Standardized Test Practice
The structure of a protein can be altered dramatically by the exchange of a single amino acid for another.
A. TrueB. False