why do we need proteins?
DESCRIPTION
Why Do We Need Proteins?. Cell Structure Cell = 80% protein. Cell membrane. Why Do We Need Proteins?. Cell Processes Hormones (signals) Enzymes (speed up reactions). Why Do We Need Proteins?. Membrane Channels (remember transport?) Neurotransmitters (carry nerve/brain messages). - PowerPoint PPT PresentationTRANSCRIPT
Why Do We Need Proteins?Why Do We Need Proteins?
1.1. Cell StructureCell Structure• Cell = 80% proteinCell = 80% protein
Cell membrane
Why Do We Need Proteins?Why Do We Need Proteins?
2.2. Cell ProcessesCell Processes• Hormones (signals)Hormones (signals)• Enzymes (speed up reactions)Enzymes (speed up reactions)
Why Do We Need Proteins?Why Do We Need Proteins?• Membrane Channels (remember transport?)Membrane Channels (remember transport?)
• Neurotransmitters (carry nerve/brain Neurotransmitters (carry nerve/brain messages)messages)
What Do We Need For What Do We Need For Protein Synthesis?Protein Synthesis?
1.1.DNADNA – Template for making mRNA during Template for making mRNA during
TranscriptionTranscription
What Do We Need For What Do We Need For Protein Synthesis?Protein Synthesis?
2. 2. RNARNAa.a. mRNAmRNA = (messenger RNA) makes = (messenger RNA) makes
and takes copy of DNA to cytoplasmand takes copy of DNA to cytoplasm
b.b. tRNAtRNA = (transfer RNA) Matches w/ = (transfer RNA) Matches w/ mRNA on ribosome and carries AA to mRNA on ribosome and carries AA to add to protein chainadd to protein chain
What Do We Need For What Do We Need For Protein Synthesis?Protein Synthesis?
3. 3. RibosomeRibosome
Reads mRNAReads mRNA
Directs tRNADirects tRNA
Creates peptide bonds between AAsCreates peptide bonds between AAs
(makes polypeptide chain)(makes polypeptide chain)
What Do We Need For What Do We Need For Protein Synthesis?Protein Synthesis?
4. 4. Amino AcidsAmino Acids (AAs) (AAs)• Building blocks of proteins Building blocks of proteins
(20 AAs exist)(20 AAs exist)• Protein = AA chain Protein = AA chain
= polypeptide chain= polypeptide chain• ORDER MATTERS!ORDER MATTERS!
AA order determines function of proteinAA order determines function of protein
Steps of Protein SynthesisSteps of Protein Synthesis1.1. Transcription (writing the “message”)Transcription (writing the “message”)
DNADNAmRNAmRNA
messenger carries code to cytoplasmmessenger carries code to cytoplasm
2.2. Translation (reading the “message”)Translation (reading the “message”)
mRNA mRNA tRNA tRNA protein (AA chain)protein (AA chain)
message translated into a message translated into a proteinprotein
TranscriptionTranscription
DNA to mRNADNA to mRNA
1.1. Location = nucleusLocation = nucleus
2.2. StepsSteps
a. a. EnzymeEnzyme binds to DNA, unzips it binds to DNA, unzips it
b. mRNA copy of gene made from DNA b. mRNA copy of gene made from DNA templatetemplate
*U replaces T in RNA*U replaces T in RNA
TranscriptionTranscription
3 DNA nucleotides (3 DNA nucleotides (triplettriplet) to ) to mRNA mRNA codoncodon
Codons
TranslationTranslationmRNA to tRNA to protein (AA chain)mRNA to tRNA to protein (AA chain)
Location = cytoplasmLocation = cytoplasm
(first (first codoncodon in mRNA is the in mRNA is the start codonstart codon))
TranslationTranslation
Steps of TranslationSteps of Translation
1. mRNA moves to cytoplasm, binds to 1. mRNA moves to cytoplasm, binds to ribosomeribosome
2. tRNA 2. tRNA anticodonanticodon UAC brings AA UAC brings AA (methionine) to mRNA (methionine) to mRNA codoncodon on on ribosomeribosome
TranslationTranslation3. Ribosome moves down mRNA to next 3. Ribosome moves down mRNA to next codoncodon
4. tRNA 4. tRNA anticodonanticodon brings & attaches next AA brings & attaches next AA with peptide bondwith peptide bond
TranslationTranslation
55. tRNA. tRNA leaves ribosome leaves ribosome
once AA attachedonce AA attached
tRNA
mRNA
AA
Protein chain
TranslationTranslation6. Steps 1-5 repeated, adding AAs6. Steps 1-5 repeated, adding AAs
until until STOP CODONSTOP CODON signals end of signals end of proteinprotein
7. Polypeptide chain released from ribosome7. Polypeptide chain released from ribosome
Synthesis PracticeSynthesis Practice
ACUUGAACTAGAUCUAGAUAUAUATATCCUGGACCTGGACCUGGAUACAUGTAC
tRNA(anti-codon)
mRNA(codon)
DNA(triplet)
Synthesis PracticeSynthesis Practice
ACTACTAGAAGATATTATCCTCCTGGAGGATACTAC
DNADNA(triplet)(triplet)
ACUACUUGAUGAAGAAGAUCUUCUUAUUAUAUAAUACCUCCUGGAGGAGGAGGACCUCCUUACUACAUGAUG
tRNAtRNA(anti-(anti-
codon)codon)
mRNAmRNA(codon)(codon)
StopStop
SerSerSerineSerine
IleIleIsoleucineIsoleucine
GlyGlyGlycineGlycine
ProProProlineProline
Met (Start)Met (Start)MethionineMethionine
AminoAmino
AcidAcid