Chapter 6 Genome
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Transcript of Chapter 6 Genome
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Genome:Allthe genetic information in a cell
Chromosome: Structure containing DNAphysically carries hereditary information;
the chromosomes contain the genes
Gene: A segment of DNA that encodes a functional product
Product: usually a protein
Genetics: The study of what genes are
how they carry information
how information is expressed
how genes are replicated
Genomics: The molecular study of genomes
Genotype: The genes of an organism codes for particular characteristics of an organism,potential properties
Phenotype: Expression of the genes (the actual expresses properties)
the manifestation of a genotype
Is
The complementary structure ofthe nitrogenous base sequence is the key to understanding
DNA replication.
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Polymer of nucleotides:
Adenine
thymine
cytosine
guanine
DNA polymer can add nucleotidesto the 3 end only!!
Double helix associated with proteins
"Backbone" is deoxyribose-phosphate
Strands are held together by:hydrogen bonds between AT and CG
DNA strands are antiparallel
Semiconservative Replication
New double strand
Ccc contains
thymine is present on theoriginal strand, only
adenine can fit into place
on new strand.guanine on original
strand, Only cytosine can
fit.
-Bases that r improperlypaired, are replaced by
replication enzymes.- Parental DNA continuesto unwind to allow
addition on the next
nucleiotide.Point @ which replication
occurs called replicationfork
New double strandedDNA molecules contain:
One original strand
One new stand
Paired DNA strands are
oriented on in opposite
directions of each other.Sugar phosphate upside
down
End having a
phosphate
attached to
the 5 carbon
is called
5 end
End having a
hydroxylattached tothe 3 carbon
is called3 end
Difference b/t ATP and adenine nucleotide
in DNA is Deoxyribose the sugar innucleotides that synthesizes DNA
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DNA Synthesis DNA Synthesis
DNA is copied by: DNA polymerase
(enzyme)In the 5'3' direction (new strand is
built in this direction)
Initiated by an RNA primer
Leading strand is synthesized
continuously
Lagging strand is synthesizeddiscontinuously
Okazaki fragments
RNA primers are removed and Okazaki
fragments joined by a DNA polymeraseand DNA ligase
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DNA Synthesis
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Replication of Bacterial DNA
Give a clinical application of genomics. 8-1
Why is the base pairing in DNA important? 8-2
Describe DNA replication, including the functions of DNA gyrase, DNA
ligase, and DNA polymerase. 8-3
Separate dark purple strand. Circular chromosome in bacteria
Goal : To take parent DNA and creating identical daughter DNA
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Transcription
DNA is transcribed to make RNA (mRNA, tRNA, and rRNA)
Genetic info stored in DNA is rewritten so the same information is in the
base sequence of mRNA DNA mRNA
G C
C G
T AA U
Transcription-begins (requires) when RNA polymerase binds to the site
promoter sequence, starts building (RNA Polymerase bound to DNA)
Transcription proceeds(like DNA, RNA) is synthesized in the 5'3'
direction (Process - RNA Polymearase (enzyme), bind s topromoter, DNA un-winds @ beginning of gene)
RNA is created by base pairing rules (complementery base pairing rules
Adine uricile No thymine in RNA
Makeing RNA only uses one (of the two) DNA stran, continue adding until
teminater
Transcription stops when it reaches theterminator sequence
mRNA carries the coded information for making specific proteins, From: DNA
ribosomes, where proteins are synthesized
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The Process of Transcription
Translation:
mRNA is translated in codons (grouping of three nucleotides) AUG initiates
protein synthesis.
Codons are written in their base sequence in mRNA- the sequence code on mRNA
molecules determines, the sequence of amino acids that will be in the protein synthesis
Translation ofmRNAbegins at the start codon: (AUG)
Translation ends at nonsense codons(do not code for amino acids):UAA, UAG, UGA-
end protein synthesis
Protein synthesis is called Translation
Involves: decoding nucleic acids Converting the information into proteins
The Genetic Code: 64 sense codons on mRNA encode the
20 amino acids
The genetic code is degenerateo-
allows it change(GUU/GUC/ so on)giving flexibility. Resulting the same DNA
or P protein
tRNA carries the complementary anticodon
anticodon a sequence of three bases that is complementary to a codon.
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Simultaneous Transcription & Translation The Process of Translation
The Process of Translation
Ribosomal RNA comes in two parts, Creating first amino acid (tRNA w/AUG & mRNA)This sets up the start codon (AUG) in the proper position to allow translation to begin.
After the ribosome joins the first 2 amino acids (w/ a peptide bond) the 1st tRNA leaves ribosome.
As amino acids are brought into line, peptide bonds are formed b/t them = polypeptide chainsAll of this happens in cytoplasm
Ends when nonsense codon in the mRNA is reached.Intact Ribosome: A P E
A arriving, deliver newly arriving amino acid, tRNA leaves exp w/ amino acidP- Pone, tRNA is going to transfer, shifts Placed to A cite leaving ? empty
Methine is being passed to Leu (A site) adding 1 amino acid at a time.
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What is the role of thepromoter, terminator, and
mRNA in transcription? 8-4
How does mRNA production in
eukaryotes differ from the
process in prokaryotes? 8-5
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Regulation of Gene Expression
Constitutive genes areexpressed at a fixed rate
Protiens that used all day longconstant supply of)
Other genes are expressedonly as needed
Repressible genes on,but can be turned off
Inducible genes off,but can be turned off
Catabolite repression form ofre ression determined b lucose
Induction
Respiration
Catabolt Respiration
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RNA Processing in Eukaryotes