Objectives ► Describe the process of transcription and translation ► Know the functions of the...
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Transcript of Objectives ► Describe the process of transcription and translation ► Know the functions of the...
ObjectivesObjectives
►Describe the process of transcription Describe the process of transcription and translationand translation
►Know the functions of the three types Know the functions of the three types of RNAof RNA
►Predict the sequence of amino acids in Predict the sequence of amino acids in a polypeptide built from a DNA a polypeptide built from a DNA molecule.molecule.
Protein SynthesisProtein Synthesis
AA AA AAAA
TRANSCRIPTION TRANSLATION
DNA mRNA PROTEIN
“WRITE THEMESSAGE”
“DECODE THEMESSAGE”
RNARNAA.A. RRiboibonnucleic ucleic AAcidcid
Single strandedSingle stranded Has ribose sugarHas ribose sugar Has Has UUracil instead of racil instead of TThyminehymine
B.B. Bonding PatternBonding Pattern A - UA - U C - GC - G
3 types of RNA3 types of RNAmRNAmRNA – messenger RNA – – messenger RNA –
carries DNA “message” from the carries DNA “message” from the nucleus to the rest of the cellnucleus to the rest of the cell
tRNAtRNA – transfer RNA – brings or – transfer RNA – brings or “transfers” amino acids from the “transfers” amino acids from the cytoplasm to the ribosomes to cytoplasm to the ribosomes to assemble proteinsassemble proteins
rRNArRNA – ribosomal RNA – helps – ribosomal RNA – helps make up ribosomesmake up ribosomes
Making Proteins: 2 stepsMaking Proteins: 2 steps
1.1. TranscriptionTranscription = re-writing the = re-writing the instructions from the language of DNA instructions from the language of DNA to the language of RNAto the language of RNA
WHY? Because DNA is too large to leave WHY? Because DNA is too large to leave the nucleus, but mRNA can slip out the nucleus, but mRNA can slip out through the nuclear poresthrough the nuclear pores
2.2. TranslationTranslation = de-coding the message = de-coding the message (mRNA CODES for Amino Acids)(mRNA CODES for Amino Acids)
Transcription – making of mRNATranscription – making of mRNA
A.A. Copy part of DNA into complementary Copy part of DNA into complementary RNA strand “RNA strand “Writing of RNA using DNAWriting of RNA using DNA””
B.B. RNA polymerase RNA polymerase – enzyme that binds – enzyme that binds to DNA to use as template and to DNA to use as template and assemble RNA nucleotidesassemble RNA nucleotides
i.i. Binds to region of DNA called the Binds to region of DNA called the ‘‘promoterpromoter’ which tells the enzyme where to ’ which tells the enzyme where to startstart
ii.ii. RNA polymerase releases DNA strand when RNA polymerase releases DNA strand when RNA strand is completeRNA strand is complete
C.C. mRNA will then travel into cytoplasmmRNA will then travel into cytoplasm
Protein SynthesisProtein Synthesis
AA AA AAAA
TRANSCRIPTION TRANSLATION
DNA mRNA PROTEIN
“WRITE THEMESSAGE”
“DECODE THEMESSAGE”
TRANSLATIONTRANSLATIONA.A. The process of translating or The process of translating or
decoding the DNA message (mRNA) decoding the DNA message (mRNA) into amino acid chains (proteins)into amino acid chains (proteins)
B.B. tRNAtRNAi.i. tRNA have 3 bases on them called an tRNA have 3 bases on them called an
anticodonanticodon which pairs with the codon of which pairs with the codon of the mRNAthe mRNA
ii.ii. Each tRNA adds one amino acid that it Each tRNA adds one amino acid that it has brought from the cytoplasm making has brought from the cytoplasm making the protein chain longerthe protein chain longer
Steps of Protein SynthesisSteps of Protein Synthesis1.1. mRNA leaves nucleus and attaches to mRNA leaves nucleus and attaches to
ribosomesribosomes
2.2. tRNA with the anticodon UAC attaches tRNA with the anticodon UAC attaches to the mRNA start codon to the mRNA start codon AUGAUG to begin to begin protein chain with amino acid protein chain with amino acid methioninemethionine
3.3. Additional tRNA’s add other amino Additional tRNA’s add other amino acids to the protein chain connecting acids to the protein chain connecting them with them with peptide bondspeptide bonds
4.4. Protein synthesis continues until it Protein synthesis continues until it reaches a reaches a stop codonstop codon (UGA, UAA, UAG) (UGA, UAA, UAG)
Genetic CodeGenetic Code
A.A. Proteins are built from different Proteins are built from different combinations of 20 amino acidscombinations of 20 amino acids
B.B. AA sequence is determined by AA sequence is determined by sequence of bases in mRNAsequence of bases in mRNA
C.C. Each 3 base codon “codes” for a Each 3 base codon “codes” for a different amino aciddifferent amino acid
D.D. 64 possible codons64 possible codonsA.A. 61 code for 20 amino acids61 code for 20 amino acids
B.B. 3 are “Stop” codons3 are “Stop” codons
How do we know what Amino How do we know what Amino Acid to add?Acid to add?
USE THE mRNACODE TO TRANSLATEINTO AMINO ACID’S
mRNA – 1) AUG2) CAU3) UAC4) UGA
A U G C A U U A C U G AmRNA
CODON
MET
U A C A C UtRNA
RIBOSOMES
HIS
G U A
METTYR
A U G
HISMET
TYR
HISMET
PRACTICEPRACTICE
►DNA : T A C G A C G T A A A A A C TDNA : T A C G A C G T A A A A A C T
►mRNA: ?mRNA: ?
►tRNA: ?tRNA: ?
►Amino Acid Sequence: ?Amino Acid Sequence: ?
PRACTICEPRACTICE
►DNA : T A C - G A C - G T A - A A A - A C DNA : T A C - G A C - G T A - A A A - A C TT
►mRNA: A U G - C U G - C A U - U U U - U G mRNA: A U G - C U G - C A U - U U U - U G AA
►tRNA: U A C - G A C - G U A - A A A - A C tRNA: U A C - G A C - G U A - A A A - A C UU
►AA Seq: MET - LEU - HIS - PHE AA Seq: MET - LEU - HIS - PHE