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Transcript of Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings When a cell or organism...
![Page 1: Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings When a cell or organism reproduces, a complete set of genetic instructions must.](https://reader035.fdocuments.in/reader035/viewer/2022070323/56649d695503460f94a477be/html5/thumbnails/1.jpg)
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• When a cell or organism reproduces, a complete set of genetic instructions must pass from one generation to the next
DNA Replication
![Page 2: Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings When a cell or organism reproduces, a complete set of genetic instructions must.](https://reader035.fdocuments.in/reader035/viewer/2022070323/56649d695503460f94a477be/html5/thumbnails/2.jpg)
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• Watson and Crick’s model for DNA suggested that DNA replicated by a template mechanism
Figure 10.6
Parental (old)DNA molecule
Daughter(new) strand
DaughterDNA molecule(double helices)
![Page 3: Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings When a cell or organism reproduces, a complete set of genetic instructions must.](https://reader035.fdocuments.in/reader035/viewer/2022070323/56649d695503460f94a477be/html5/thumbnails/3.jpg)
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• DNA functions as the inherited directions for a cell or organism
THE FLOW OF GENETIC INFORMATION FROM DNA TO RNA TO PROTEIN
– How are these directions carried out?
![Page 4: Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings When a cell or organism reproduces, a complete set of genetic instructions must.](https://reader035.fdocuments.in/reader035/viewer/2022070323/56649d695503460f94a477be/html5/thumbnails/4.jpg)
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• An organism’s genotype, its genetic makeup is the sequence of nucleotide bases in DNA
How an Organism’s DNA Genotype Produces Its Phenotype
– The phenotype is the organism’s specific traits
![Page 5: Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings When a cell or organism reproduces, a complete set of genetic instructions must.](https://reader035.fdocuments.in/reader035/viewer/2022070323/56649d695503460f94a477be/html5/thumbnails/5.jpg)
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• What is the language of nucleic acids?
– In DNA, it is the linear sequence of nucleotide bases
Figure 10.10
DNA molecule
Translation
Polypeptide
Gene 1
Gene 2
Gene 3
DNA strand
Transcription
RNA
Codon
Amino acid
![Page 6: Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings When a cell or organism reproduces, a complete set of genetic instructions must.](https://reader035.fdocuments.in/reader035/viewer/2022070323/56649d695503460f94a477be/html5/thumbnails/6.jpg)
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• DNA specifies the synthesis of proteins in two stages
– Transcription
– Translation
Figure 10.9
DNANucleus
Transcription
RNA
Translation
ProteinCytoplasm
![Page 7: Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings When a cell or organism reproduces, a complete set of genetic instructions must.](https://reader035.fdocuments.in/reader035/viewer/2022070323/56649d695503460f94a477be/html5/thumbnails/7.jpg)
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• When DNA is transcribed, the result is an RNA molecule
• RNA is then translated into a sequence of amino acids in a polypeptide
![Page 8: Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings When a cell or organism reproduces, a complete set of genetic instructions must.](https://reader035.fdocuments.in/reader035/viewer/2022070323/56649d695503460f94a477be/html5/thumbnails/8.jpg)
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
Transcription: From DNA to RNA
• In transcription
– Genetic information is transferred from DNA to RNA
– An RNA molecule is transcribed from a DNA template
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Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 10.13a
RNApolymerase
RNA nucleotides
Newly madeRNA Direction of
transcriptionTemplatestrand of DNA
(a) A close-up view of transcription
![Page 10: Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings When a cell or organism reproduces, a complete set of genetic instructions must.](https://reader035.fdocuments.in/reader035/viewer/2022070323/56649d695503460f94a477be/html5/thumbnails/10.jpg)
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• Transcription of an entire gene
Figure 10.13b
RNA polymerase
DNA of gene
PromoterDNA Initiation Terminator
DNA
RNAElongation
Area shownin part (a)
TerminationGrowingRNA
Completed RNA
RNApolymerase
(b) Transcription of a gene
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Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• RNA processing includes
– Adding a cap and tail
– Removing introns
– Splicing exons together
Figure 10.14
DNA
RNAtranscriptwith capand tail
mRNA
Exon Intron ExonIntron Exon
Cap
Introns removed Tail
Exons spliced together
Coding sequence
Nucleus
Cytoplasm
TranscriptionAddition of cap and tail
![Page 12: Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings When a cell or organism reproduces, a complete set of genetic instructions must.](https://reader035.fdocuments.in/reader035/viewer/2022070323/56649d695503460f94a477be/html5/thumbnails/12.jpg)
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• Transcription and translation
– Are the processes whereby genes control the structures and activities of cells
![Page 13: Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings When a cell or organism reproduces, a complete set of genetic instructions must.](https://reader035.fdocuments.in/reader035/viewer/2022070323/56649d695503460f94a477be/html5/thumbnails/13.jpg)
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• Triplets of bases
– Specify all the amino acids
– Are called codons
![Page 14: Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings When a cell or organism reproduces, a complete set of genetic instructions must.](https://reader035.fdocuments.in/reader035/viewer/2022070323/56649d695503460f94a477be/html5/thumbnails/14.jpg)
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• The genetic code is the set of rules relating nucleotide sequence to amino acid sequence
The Genetic Code
Figure 10.11
![Page 15: Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings When a cell or organism reproduces, a complete set of genetic instructions must.](https://reader035.fdocuments.in/reader035/viewer/2022070323/56649d695503460f94a477be/html5/thumbnails/15.jpg)
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• The genetic code is shared by all organisms
Figure 10.12
![Page 16: Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings When a cell or organism reproduces, a complete set of genetic instructions must.](https://reader035.fdocuments.in/reader035/viewer/2022070323/56649d695503460f94a477be/html5/thumbnails/16.jpg)
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• Translation
Translation: The Players
– Is the conversion from the nucleic acid language to the protein language
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Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• mRNA
Messenger RNA (mRNA)
– Is the first ingredient for translation
![Page 18: Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings When a cell or organism reproduces, a complete set of genetic instructions must.](https://reader035.fdocuments.in/reader035/viewer/2022070323/56649d695503460f94a477be/html5/thumbnails/18.jpg)
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• An mRNA molecule has a cap and tail that help it bind to the ribosome
Figure 10.17
Start of genetic message
CapEnd
Tail
![Page 19: Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings When a cell or organism reproduces, a complete set of genetic instructions must.](https://reader035.fdocuments.in/reader035/viewer/2022070323/56649d695503460f94a477be/html5/thumbnails/19.jpg)
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• tRNA
Transfer RNA (tRNA)
– Acts as a molecular interpreter
– Carries amino acids
– Matches amino acids with codons in mRNA using anticodons
Figure 10.15
Amino acid attachment site
Hydrogen bond
RNA polynucleotide chain
AnticodonAnticodon
![Page 20: Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings When a cell or organism reproduces, a complete set of genetic instructions must.](https://reader035.fdocuments.in/reader035/viewer/2022070323/56649d695503460f94a477be/html5/thumbnails/20.jpg)
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• A fully assembled ribosome holds tRNA and mRNA for use in translation
Figure 10.16b
Next amino acidto be added topolypeptide
Growingpolypeptide
mRNA
tRNA
(b)
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Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
Polypeptide
Amino acid
P site
AnticodonmRNA A site
Codons
Elongation
2
3 Translocation
Codon recognition
Peptide bond formation
• The process of elongation
Figure 10.19
mRNAmovement
New peptidebond
1
![Page 22: Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings When a cell or organism reproduces, a complete set of genetic instructions must.](https://reader035.fdocuments.in/reader035/viewer/2022070323/56649d695503460f94a477be/html5/thumbnails/22.jpg)
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• A mutation
Mutations
– Is any change in the nucleotide sequence of DNA
Figure 10.21
Normal hemoglobin Sickle-cell hemoglobin
Glu Val
Normal hemoglobin DNA Mutant hemoglobin DNA
mRNA mRNA
![Page 23: Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings When a cell or organism reproduces, a complete set of genetic instructions must.](https://reader035.fdocuments.in/reader035/viewer/2022070323/56649d695503460f94a477be/html5/thumbnails/23.jpg)
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• Mutations may result from
Mutagens
– Errors in DNA replication
– Physical or chemical agents called mutagens
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Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• DNA can be damaged by ultraviolet light
– The enzymes and proteins involved in replication can repair the damage
Figure 10.7
![Page 25: Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings When a cell or organism reproduces, a complete set of genetic instructions must.](https://reader035.fdocuments.in/reader035/viewer/2022070323/56649d695503460f94a477be/html5/thumbnails/25.jpg)
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• Although mutations are often harmful
– They are the source of the rich diversity of genes in the living world
– They contribute to the process of evolution by natural selection
Figure 10.23
![Page 26: Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings When a cell or organism reproduces, a complete set of genetic instructions must.](https://reader035.fdocuments.in/reader035/viewer/2022070323/56649d695503460f94a477be/html5/thumbnails/26.jpg)
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• Viruses sit on the fence between life and nonlife
VIRUSES: GENES IN PACKAGES
– They exhibit some but not all characteristics of living organisms
Figure 10.24
![Page 27: Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings When a cell or organism reproduces, a complete set of genetic instructions must.](https://reader035.fdocuments.in/reader035/viewer/2022070323/56649d695503460f94a477be/html5/thumbnails/27.jpg)
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• Bacteriophages, or phages
Bacteriophages
– Attack bacteria
Figure 10.25
Head
Tail
Tail fiber
DNA of virus
Bacterialcell
![Page 28: Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings When a cell or organism reproduces, a complete set of genetic instructions must.](https://reader035.fdocuments.in/reader035/viewer/2022070323/56649d695503460f94a477be/html5/thumbnails/28.jpg)
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• Viruses that infect plants
Plant Viruses
– Can stunt growth and diminish plant yields
– Can spread throughout the entire plant
Figure 10.27
Protein RNA
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Figure 10.29
VIRUS
Entry1
2
3
4
Uncoating
RNA synthesisby viral enzyme
5 RNA synthesis(other strand)
Proteinsynthesis
6 Assembly
7
Exit
Viral RNA (genome)
Protein spike
Protein coat
Envelope
Plasma membrane of host cell
mRNA
New viral proteins
Template
New viral genome
![Page 30: Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings When a cell or organism reproduces, a complete set of genetic instructions must.](https://reader035.fdocuments.in/reader035/viewer/2022070323/56649d695503460f94a477be/html5/thumbnails/30.jpg)
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Signaling between biomolecules
QuickTime™ and aCinepak decompressor
are needed to see this picture.
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• Gene therapy