The Gene expression = the Transfer of the genetic information
Replication
- duplication of DNA
location:
purpose:
result:
requirements:
▪ DNA template
▪ deoxyribonucleotides - dATP, dCTP, dGTP, dTTP
▪ enzyme DNA-polymerase (catalyzes the synthesis of DNA)
▪ ATP – source of energy
▪ Mg2+
mechanism:
- two strands of DNA unwind and each act as a template for synthesis of new strands according to
the principle of complementarity
- the process is catalyzed by DNA-polymerase
Transcription
- transcript of the genetic information from the structure of DNA into the structure of m-RNA
location:
purpose:
result:
requirements:
▪ DNA template – but only one strand is used
▪ ribonucleotides – ATP, UTP, CTP, GTP
▪ enzyme RNA-polymerase (catalyzes the synthesis of m-RNA)
▪ ATP
▪ Mg2+
mechanism:
- two strands of DNA unwind partially
- only one strand of DNA is used as a template for synthesis of a new chain of m-RNA according to
the principle of complementarity (A → U, C → G, T → A)
- the process is catalyzed by RNA-polymerase
- synthesis is going from the 5'-end towards the 3'-end
Translation
- transformation of the genetic information from the “language” of nucleotides into the sequences
of amino acids in the polypeptide chain (protein)
location:
purpose:
result:
requirements:
▪ m-RNA → triplet = codon = a sequence of three adjacent nucleotides in m-RNA
▪ t-RNA →triplet = ………………………… = a sequence of three adjacent nucleotides in t- RNA that
binds to a corresponding codon in messenger RNA and designates a specific amino acid during
protein synthesis
▪ r-RNA
▪ proteinogenic amino acids
▪ enzymes
▪ ribosomes
▪ GTP, ATP – sources of energy
▪ Mg2+, K+
mechanism:
- m-RNA produced in the nucleus transports into the cytoplasm
- m-RNA binds with ribosome’s subunits
translation begins in ………………………… codon = AUG
- t-RNA transfers proteinogenic amino acids into the ribosome to form polynucleotide chain based
on the principle of complementarity between nitrogenous bases of codon of m-RNA and anticodon
of t-RNA
- amino acids bond by peptide bond
- translation stops in ………………………… codon = UAA, UGA, UAG = ………………………… codon
Messenger RNA Codons - Amino Acids
Second Base
First Base
5'End
Third Base 3'End
U
C
A
G
U
UUU
U
UUC
UUA
UUG
Phenylalanine (Phe)
UCU
UAU
UCC
UAC
UCA
Leucine (Leu)
Serine (Ser)
UCG
Tyrosine (Tyr)
UAA
Stop (Terminators)
UAG
UGU
UGC
Cysteine (Cys)
UGA Stop (Terminator)
UGG Tryptophan (Try)
C
A
G
U
C
CUU
CCU
CUC
CCC
CUA
Leucine (Leu)
CCA
CUG
CAU
Proline (Pro)
CCG
CAC
CAA
CAG
CGU
Histine (His)
CGC
C
CGA Arginine (Arg)
Glutamine (Gln)
CGG
A
G
U
AUU
A
AUC Isoleucine (Iso)
ACU
AAU
AUA
ACC
AAC
AUG Methionine (Met)*
Start Codon *
ACA
Threonine (Thr)
ACG
AAA
AAG
Asparagine (Asn)
Lysine (Lys)
AGU
AGC
AGA
AGG
Serine (Serine)
C
Arginine (Arg)
A
G
U
G
GUU
GCU
GAU
GUC
GCC
GAC
GUA
Valine (Val)
GCA
GUG
Alanine (Ala)
GCG
GAA
GAG
Aspartic Acid (Asp)
Glutamic Acid (Glu)
GGU
GGC
GGA
C
Glycine (Gly)
GGG
A
G
Task 1
Using the Messenger RNA Codon Chart above, identify the amino acids that would be carried by each of the
following codons.
Codon
Amino Acid
. Codon
Amino Acid
AUU = ____________________ . UGG = ____________________
GGA = ____________________ . GAA = ____________________
AUG = ____________________ . GAU = ____________________
UCU = ____________________ . CCC = ____________________
Task 2
The transfer RNA molecules which carry the amino acids have three unpaired nucleotide bases called
"anticodons". The anticodons are complimentary to the codons carried on the mRNA. What would be the
anticodons for the following codons?
Codon
Anticodon
. Codon
Anticodon
AUU = ____________________ . UGG = ____________________
GGA = ____________________ . GAA = ____________________
AUG = ____________________ . GAU = ____________________
UCU = ____________________ . CCC = ____________________
Task 3
Using the Messenger RNA Codon Chart, complete the following table and identify the amino acid
(polypeptide) sequence that would be made from the following DNA sequence.
DNA
Sequence
3' - T. A..C .A ..A. G .C. G..C. A .C..A .T. C..C..T .T .A. G. G G .A .C .T - 5'
m RNA
(codons)
tRNA
(anticodons)
Amino Acid
Sequence
Task 4
Write the codons of the m-RNA, if you know that it codes following parts of the polypeptide chain.
a. … - phenylalanine – proline – proline – serine - …
b. … - threonine – tryptophan – tyrosine – valine - …
c. … - alanine – glycine – aspartic acid – glutamine – methionine - …
Task 5
Transcribe the following gene:
5'-CCCTATATPROMOTERCGCGATGAAAGGGCCCTGAGGTERMINATORAAAAA-3'
3'-GGGATATAPROMOTERGCGCTACTTTCCCGGGACTCCTERMINATORTTTTT-5'
Task 6
Use the genetic code to identify which of the following nucleotide sequences would code for
the polypeptide sequence arginine‐glycine‐aspartate:
a.
b.
c.
d.
5’‐AGAGGAGAU‐3’
5’‐ACACCCACU‐3’
5’‐GGGAAAUUU‐3’
5’‐CGGGGUGAC‐3’