© 2010 pearson education, inc. review: dna rna protein in a cell, genetic information flows from...

© 2010 Pearson Education, Inc.

Review: DNA RNA Protein• In a cell, genetic information flows from DNA to RNA in the

nucleus and RNA to protein at the ribosome.

Transcription RNA polymerase

mRNA DNA

Intron

Nucleus

Figure 10.20-1


mRNA DNA

Intron

Nucleus

mRNAIntron

TailCap

RNA processing

tRNA

Amino acid

Amino acidattachment

EnzymeATP Initiation

of translation

Ribosomalsubunits

Figure 10.20-4


mRNA DNA

Intron

Nucleus

mRNAIntron

TailCap

RNA processing

tRNA

Amino acid

Amino acidattachment

EnzymeATP Initiation

of translation

Ribosomalsubunits

Elongation

AnticodonCodon

Termination

Polypeptide

Stopcodon

Figure 10.20-6


• Transcription and translation are how genes control:

– The structures

– The activities of cells


Mutations

• A mutation is any change in the nucleotide sequence of DNA.

• Mutations can change the amino acids in a protein.

• Mutations can involve:

– Large regions of a chromosome

– Just a single nucleotide pair, as occurs in sickle cell anemia


How can Mutations be BAD?

How can Mutations be GOOD?


• Although mutations are often harmful, they are the source of genetic diversity, which is necessary for evolution by natural selection.


Mutagens

• Mutations may result from:

– Errors in DNA replication

– Physical or chemical agents called mutagens

– UV rays, X-rays, gamma rays, chemicals


Types of Mutations

• Mutations within a gene can occur as a result of:

– Nucleotide substitution, the replacement of one nucleotide by another

– Nucleotide deletion, the loss of a nucleotide

– Nucleotide insertion, the addition of a nucleotide


If a mutation changed a codon from GGU to GGA then what would happen?

If a mutation changed a codon from GGA to UGA then what would happen?

Normal hemoglobin DNA

mRNA

Normal hemoglobin

Mutant hemoglobin DNA

mRNA

Sickle-cell hemoglobin

Figure 10.21


• Insertions and deletions can:

– Change the reading frame of the genetic message

– Lead to disastrous effects

mRNA and protein from a normal gene

Base substitutionFigure 10.22a

Deleted

Nucleotide deletion


Figure 10.22b


Inserted

Nucleotide insertion Figure 10.22c


Deleted

(a) Base substitution

Inserted(b) Nucleotide deletion

(c) Nucleotide insertionFigure 10.22


Mutation by Deletion:


The Human Genome Project• Begun in 1990, the Human Genome Project was a massive

scientific endeavor:

– To determine the nucleotide sequence of all the DNA in the human genome and

– To identify the location and sequence of every gene

- Aims of the project:

- to identify the estimated 100,000 genes in the human DNA.


• At the completion of the project in 2004:

– Over 99% of the genome had been determined to 99.999% accuracy

– 3.2 billion nucleotide pairs were identified

– About 24,000 genes were found

– About 98% of the human DNA was identified as noncoding


• The Human Genome Project can help map the genes for specific diseases such as:

– Alzheimer’s disease

– Parkinson’s disease


Benefits of Human Genome Project research

- improvements in medicine.

- microbial genome research for fuel and environmental cleanup.

- DNA forensics.

- improved agriculture and livestock.

- better understanding of evolution and human migration.

- more accurate risk assessment.


Making Humulin

• In 1982, the world’s first genetically engineered pharmaceutical product was sold.

• Humulin, human insulin:

– Was produced by genetically modified bacteria

– Was the first recombinant DNA drug approved by the FDA

– Is used today by more than 4 million people with diabetes


• Today, humulin is continuously produced in gigantic fermentation vats filled with a liquid culture of bacteria.


If a strand of DNA has the sequence AAGCTC, transcription will result in a(n) ______.A) single RNA strand with the sequence TTCGAGB) DNA double helix with the sequence AAGCTC for one strand and TTCGAG for the complementary strandC) single DNA strand with the sequence TTCGAGD) single RNA strand with the sequence UUCGAGE) RNA double helix with the sequence UUCGAG for one strand and AAGCUC for the complimentary strand


Translation converts the information stored in ______ to ______.A) DNA . . . RNAB) RNA . . . a polypeptideC) protein . . . DNAD) DNA . . . a polypeptideE) RNA . . . DNA


Where is translation accomplished?A) lysosomesB) smooth endoplasmic reticulumC) peroxisomesD) ribosomesE) nucleoli


A mutation within a gene that will insert a premature stop codon in mRNA would ______.A) result in a polypeptide that is one amino acid shorter than the one produced prior to the mutationB) result in a shortened polypeptide chainC) result in a missense mutationD) change the location at which transcription of the next gene beginsE) have the same effect as deleting a single nucleotide in the gene


What is the smallest number of nucleotides that must be added or subtracted to change the triplet grouping of the genetic message?A) oneB) twoC) threeD) fourE) five


Examine the genetic code table, shown below. The codon AGC codes for the amino acid ______.

A) serineB) arginineC) threonineD) alanineE) glycine


A mutation would be most harmful to the cells if it resulted in ______.A) a single nucleotide insertion near the start of the coding sequenceB) a single nucleotide deletion near the end of the coding sequenceC) a single nucleotide in the middle of an intronD) substitution of a base pairE) deletion of a triplet near the middle of the gene


In a DNA double helix, adenine pairs with ______ and guanine pairs with ______.A) cytosine . . . thymineB) guanine . . . adenineC) uracil . . . cytosineD) thymine . . . cytosineE) cytosine . . . uracil


RNA contains the nitrogenous base ______ instead of ______, which is only found in DNA.A) a deoxyribose sugar . . . a ribose sugarB) nucleotides . . . nucleic acidsC) uracil . . . thymineD) cytosine . . . guanineE) adenine . . . guanine


If one strand of a DNA double helix has the sequence GTCCAT, what is the sequence of the other strand?A) ACTTGCB) TGAACGC) CAGGTAD) CAGGUAE) CUGGTU


What name is given to the collection of traits exhibited by an organism?A) holotypeB) genotypeC) typologyD) phenotypeE) morphology


How many nucleotides make up a codon?A) oneB) twoC) threeD) fourE) five


Transcription is the ______.A) manufacture of a strand of RNA complementary to a strand of DNAB) manufacture of two new DNA double helices that are identical to an old DNA double helixC) modification of a strand of RNA prior to the manufacture of a proteinD) manufacture of a protein based on information carried by RNAE) manufacture of a new strand of DNA complementary to an old strand of DNA

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