RNA and Protein Synthesis Ribonucleic acid : another type of nucleic acid that works with DNA to make proteins
Jan 04, 2016
RNA and Protein Synthesis
Ribonucleic acid: another type of nucleic acid that works with DNA
to make proteins
mRNA
From nucleus to cytoplasm
DNA
transcription
nucleus cytoplasm
translation
trait
aa
aa
aa
aa
aa
aa
aa
aaaa
aa
protein
DNA vs. RNADNA deoxyribose sugar nitrogen bases
G, C, A, TT : AC : G
double stranded 1 type
RNA ribose sugar nitrogen bases
G, C, A, UU : AC : G
single stranded 3 types: M, R, & T
Transcription Making mRNA from DNA DNA strand is the
template (pattern)match bases
U : A G : C
EnzymeRNA polymerase
Matching bases of DNA & RNA Double stranded DNA unzips
A G GGGGGT T A C A C T T T T TC C C CA A
Matching bases of DNA & RNA Double stranded DNA unzips
A G GGGGGT T A C A C T T T T TC C C CA A
Matching bases of DNA & RNA Match RNA bases to DNA
bases on one of the DNA strands
U
A G GGGGGT T A C A C T T T T TC C C CA A
U
UU
U
U
G
G
A
A
A C CRNA polymerase
C
C
C
C
C
G
G
G
G
A
A
A
AA
Matching bases of DNA & RNA U instead of T is matched to A
TACGCACATTTACGTACGCGGDNA
AUGCGUGUAAAUGCAUGCGCCmRNAaa
aa
aa
aa
aa
aa
aa
aaaa
aa
U C CCCCCA A U G U G A A A A AG G G GU Uribosome
aa
aa
aa
aa
aa
aa
aa
aaaa
aa
protein
cytoplasm
nucleus
traitU C CCCCCA A U G U G A A A A AG G G GU U
ribosome
How does mRNA code for proteins mRNA leaves nucleus mRNA goes to ribosomes in cytoplasm Proteins built from instructions on mRNA
aa aa aa aa aa aa aa aa
How?
mRNA
U C CCCCCA A U G U G A A A A AG G G GU U
How does mRNA code for proteins?
TACGCACATTTACGTACGCGGDNA
AUGCGUGUAAAUGCAUGCGCCmRNA
Met Arg Val Asn Ala Cys Alaprotein
?
How can you code for 20 amino acids withonly 4 DNA bases (A,U,G,C)?
ribosome
aa aa aa aa aa aa aa aa
AUGCGUGUAAAUGCAUGCGCCmRNA
mRNA codes for proteins in triplets
TACGCACATTTACGTACGCGGDNA
AUGCGUGUAAAUGCAUGCGCCmRNA
Met Arg Val Asn Ala Cys Alaprotein
?
Codon = block of 3 mRNA bases
codon
ribosome
For ALL life!strongest support
for a common origin for all life
Code has duplicatesseveral codons for
each amino acidmutation insurance!
Start codonAUGmethionine
Stop codonsUGA, UAA, UAG
The mRNA code
How are the codons matched to amino acids?
TACGCACATTTACGTACGCGGDNA
AUGCGUGUAAAUGCAUGCGCCmRNA
anti-codon
codon
tRNAUAC
MetGCA
ArgCAU
Val Anti-codon = block of 3 tRNA bases
aminoacid
mRNA to protein = Translation The working instructions mRNA The reader ribosome The transporter transfer RNA (tRNA)
mRNAU C CCCCCA A U G U G A A A A AG G G GU U
aaaa
aa
tRNA
GGU
aa
tRNA
U A C
aa
tRNA
GA C
tRNA
aa
A GU
ribosome
aa
aa
aaaa
aa
aa
aa
mRNA
From gene to protein
DNA
transcription
nucleus cytoplasm
protein
translation
trait
U C CCCCCA A U G U G A A A A AG G G GU Uribosome
tRNA
aa
MutationsChanges to DNA are called mutations
change the DNAchanges the mRNAmay change proteinmay change trait
DNA TACGCACATTTACGTACG
mRNA AUGCGUGUAAAUGCAUGC
aa aa aa aa aa aa aaprotein
trait
Types of Mutations
1.Point mutation: change in a single base pair in DNA (substitution) THE DOG BIT THE CAT THE DOG BIT THE CAR
Missense mutation = changes amino acidNonsense mutation = change to STOPSilent mutation = no change in protein
Types of Mutations
2. Frameshift mutation: a single base pair is added or deleted and shifts the reading of the codons
THE DOG BIT THE CAT
THE DOG SBI TTH ECA T
Mutations
3. Chromosomal mutations: any change in the structure or number of chromosomes, common in plants deletion: part of a chromosome is removed insertion and translocation: part of a
chromosome breaks off and attaches to another chromosome
inversion: part of a chromosome breaks off and is reinserted backwards
Examples of chromosomal mutations
deletion
duplication
inversion
translocation
12.4
Gene Regulation
Only a small percent of genes are expressed (~3%)
Genes that are expressed have a proteins that control their expression
“TATA box”: sequence at the beginning of a transcription site in eukaryotes
The Operon
Four regions of DNA control the production of a protein
a structural gene that holds the codons for the amino acid sequence found in the enzyme.
an operator region right in front of the structural gene.
a promotor region where the RNA polymerase will bind to the DNA.
a regulator gene which has a role in controling the transcription from the structural gene.
The combined region of the operator and structural gene is called an operon.
Animations
http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter15/animations.html#
http://learn.genetics.utah.edu/units/basics/firefly/