RNA and Protein Synthesis Genes are coded DNA instructions that control the production of proteins DNA is like the master plan RNA contains coded information for making proteins RNA ID: 634821
Download Presentation The PPT/PDF document "Chapter 13 RNA and Protein Synthesis" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Chapter 13
RNA and Protein SynthesisSlide2
RNA and Protein Synthesis
Genes
are coded
DNA instructions that control the production of proteins. DNA is like the master plan.RNA contains coded information for making proteins.Slide3
RNA vs. DNA
3 main differences
The sugar in RNA is
ribose instead of deoxyriboseRNA is usually single stranded
RNA contains Uracil instead of ThymineYou can think of RNA as a disposable copy of a segment of DNASlide4
From Gene to Protein
Transcription and Translation
The process of producing a protein from DNA involves a series of steps
A) Transcription – DNA to mRNAB) Translation – mRNA to proteinSlide5
RNA
There are 3 types of RNA
Messenger
RNA (mRNA)Ribosomal RNA (rRNA)Transfer RNA (tRNA)Slide6
Types of RNA
Messenger RNA
(mRNA)
carries copies of
instructions for assembling amino acids into proteins. (from DNA to the rest of the cell)
mRNASlide7
rRNA
Ribosomes
are made up of
proteins and
ribosomal RNA (rRNA).Slide8
During protein construction,
transfer
RNA
(tRNA) transfers each amino acid to the ribosome.
Amino acid
Transfer RNA
tRNASlide9
From Gene to Protein
Transcription
: the process of making mRNA from a DNA
templateSince DNA is found in the nucleus and ribosomes are found in the cytoplasm, the instructions in DNA must be carried out of the nucleus to the ribosomes in order to make the proteinDone by messenger RNA
(mRNA)Slide10
From Gene to Protein
Transcription
The process of transcription is done by the enzyme
RNA polymeraseRNA polymerase binds to the section of DNA that is to be transcribed, “unzips” the DNA, and promotes the synthesis of the mRNA moleculeSlide11
Promoter
3
¢
5
Transcription unit
DNA
Initiation
RNA polymerase
Start point
Template strand
of DNA
RNA
tran-
script
Unwound
DNA
Elongation
3
¢
3
¢
5
¢
3
5
¢
5
¢
3
¢
5
¢
Rewound
DNA
5
¢
3
¢
3
¢
5
¢
3
¢
5
¢
RNA
transcript
Termination
3
¢
5
¢
5
¢
3
¢
Completed RNA transcriptSlide12
From Gene to Protein
Transcription
The addition of RNA bases follows the same base pairing rules as DNA replicationException: the base uracil replaces thymineC-G and A-U
RNA
polymerase
Direction of transcription
(“downstream”)
Template
strand of DNA
Non-template
strand of DNA
RNA nucleotidesSlide13
From Gene to Protein
Transcription
In eukaryotic cells, after mRNA is synthesized it must be modified
1) the ends of the mRNA are modifiedDone to promote the safe export of the mRNA out of the nucleus and to assist ribosome binding to the mRNA strand2) non-coding sections of the mRNA, called introns
, are cut out and the remaining coding sections, called exons, are spliced togetherSlide14
5
¢
Protein-coding segment
5
¢
Start codon
Stop codon
Poly-A tail
Polyadenylation signal
5
¢
3
¢
Cap
UTR
UTRSlide15
5
¢
Exon
Intron
Exon
Intron
Exon
3
¢
Pre-mRNA
1
30
31
104
105
146
Coding
segment
Introns cut out and
exons spliced together
1
146
5
¢
Cap
5
¢
Cap
Poly-A tail
Poly-A tail
5
¢
3
¢
UTR
UTRSlide16
From Gene to Protein
The Genetic Code
How does DNA know which amino acid to place into the new protein?
It has been determined that the sequence of bases in DNA contains the information necessary to produce specific proteinsThis sequence of bases is called the genetic codeSlide17
From Gene to Protein
The Genetic Code
(cont.)
Scientists have been able to interpret the genetic codeThrough experimentation, it has been determined that groups of three bases make up “words” in DNA languageEach group of three bases is called a codonThere are 64 total codons found in the genetic codeSlide18
The Genetic Code
A
codon
consists of three consecutive nucleotides on mRNA that specify a particular amino acid.Copyright Pearson Prentice HallSlide19
Copyright Pearson Prentice Hall
The Genetic CodeSlide20
DNA
molecule
Gene 1
Gene 2
Gene 3
DNA strand
(template)
3
¢
TRANSCRIPTION
Codon
mRNA
TRANSLATION
Protein
Amino acid
3
¢
5
¢
5
¢