Gene Expression From genotype to phenotype. From Gene to Protein DNA In Genes Transcription RNA is...
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Transcript of Gene Expression From genotype to phenotype. From Gene to Protein DNA In Genes Transcription RNA is...
Gene ExpressionGene Expression
From genotype to From genotype to phenotypephenotype
From Gene to ProteinFrom Gene to Protein
DNAIn Genes
TranscriptionRNA is created
Translation
Amino Acids are sequenced into a protein.
Proteins are physical expression of gene =phenotype
A gene is a specific sequence of a DNA molecule that codes for a protein.
TRANSLATION
TRANSCRIPTION
RNA PROCESSING
Structure of RNAFormed from Formed from
nucleotide subunitsnucleotide subunitsSingled StrandedSingled StrandedUracil instead of Uracil instead of
ThymineThymineSugar is riboseSugar is ribose
Look familiar?Look familiar?
TranscriptionTranscription RNA polymeraseRNA polymerase pries the DNA strands pries the DNA strands
apart and hooks together the RNA apart and hooks together the RNA nucleotidesnucleotides
RNA synthesis follows the same base-RNA synthesis follows the same base-pairing rules as DNA, except uracil pairing rules as DNA, except uracil substitutes for thyminesubstitutes for thymine
Watch it in action!
Elongation
RNApolymerase
Nontemplatestrand of DNA
RNA nucleotides
3 end
Direction oftranscription(“downstream”) Template
strand of DNA
Newly madeRNA
3
5
5
Promoter Codon
Terminator Codon
Transcription produces three types Transcription produces three types of RNAof RNA
•Ribosomal RNA (brown) makes up ribosomes. rRNA•Messenger RNA (pink): provides template mRNA•Transfer RNA (green): transfers amino acids to ribosome tRNA
CodonsCodons Specific sequence of Specific sequence of
three nucleotides on three nucleotides on the mRNA.the mRNA.
Used to code for Used to code for amino acids.amino acids.
The Genetic Code The Genetic Code Chart is based on Chart is based on codons.codons.
TranslationTranslation
Changing from the language of Changing from the language of nucleotides, to the language of nucleotides, to the language of amino acids.amino acids.
Codon (mRNA)
UUUTranslation
Amino Acid
Phenylalanine
Codon sequence ties to specific Codon sequence ties to specific amino acidsamino acids
Second letterU C A G
Fir
st
lett
er
(5’
en
d)
U
C
A
G
Th
ird
lett
er
(3’
en
d)
UCAG
UCAG
UCAG
UCAG
= Stop Codon
= Start Codon
Translation happens Translation happens with the help of with the help of tRNAtRNA
Each tRNA has:Each tRNA has:– anti-codonanti-codon– Attached amino acidAttached amino acid
Example:Example:– Amino Acid: LeucineAmino Acid: Leucine– Codon (mRNA): CUUCodon (mRNA): CUU– Anti-codon (tRNA): GAAAnti-codon (tRNA): GAA Anti-
codon
Translation Stage 1: InitiationTranslation Stage 1: Initiation1.1. Small ribosomal subunit binds AUG Small ribosomal subunit binds AUG
sequencesequence• AUG codon signals start of sequenceAUG codon signals start of sequence• AUG codes for methionine (Met)AUG codes for methionine (Met)
2.2. Large subunit then bindsLarge subunit then binds
Translation Stage 2: ElongationTranslation Stage 2: Elongation
Watch it!
Translation Stage 3: TerminationTranslation Stage 3: Termination
Ribosome reaches a stop codon on Ribosome reaches a stop codon on mRNA.mRNA.
New protein is released from New protein is released from ribosome.ribosome.
Ribosome subunits disconnect.Ribosome subunits disconnect.
RNA splicing• Most eukaryotic genes and their RNA Most eukaryotic genes and their RNA
transcripts (mRNA) have long noncoding transcripts (mRNA) have long noncoding stretches of nucleotides that lie stretches of nucleotides that lie between coding regionsbetween coding regions
• Noncoding regions are called Noncoding regions are called intronsintrons• The other regions are called The other regions are called exonsexons
because they are because they are exexpressedpressed• translated into amino acid sequencestranslated into amino acid sequences
• RNA splicingRNA splicing removes introns and joins removes introns and joins exons (spliceosome)exons (spliceosome)• creating an mRNA molecule with a continuous creating an mRNA molecule with a continuous
coding sequencecoding sequence
RNA splicing
5 Exon Intron Exon Intron Exon 3Pre-mRNA
1 30 31 104 105 146
Codingsegment
Introns cut out andexons spliced together
1 1465Cap
5Cap
Poly-A tail
Poly-A tail
5 3UTR UTR
Exon = expressedIntron = spliced out
MutationsMutations– Base substitution mutationsBase substitution mutations– Base insertion or deletionsBase insertion or deletions
One or two nucleotide pairs are inserted into or One or two nucleotide pairs are inserted into or deleted from the moleculedeleted from the molecule
Frameshift mutationFrameshift mutation
MutationsMutations
The Jamba Juice AnalogyThe Jamba Juice AnalogyFor protein synthesisFor protein synthesis
ProductsProducts
Jamba Juice ProductJamba Juice Product
Various flavored Smoothies!Various flavored Smoothies!
Cell ProductCell Product
Various proteinsVarious proteins
Nucleus of the operation. Locked inside this building Nucleus of the operation. Locked inside this building are the recipes for all Jamba Juice smoothies.are the recipes for all Jamba Juice smoothies.
Recipes =Recipes = ???? Building = ??Building = ??
Jamba Juice Corporate Jamba Juice Corporate Headquarters, Emeryville, CAHeadquarters, Emeryville, CA
Transcribing the recipesTranscribing the recipes
mRNA
Jamba Juice StoresJamba Juice Stores
rRNA/ribosomes
Transport of materials to storesTransport of materials to stores
tRNA
Jamba Juice MixologistsJamba Juice Mixologists
Mixologists are the A and P sites in the ribosome –Translates recipe (codons) to fruit ingredients (amino acids)
Jamba Juice SmoothieJamba Juice Smoothie
Combines fruits (amino acids) into a smoothie (protein).