DNA TRANSLATION
Gr. 11 ls 8.5
RECALL THAT
•Central dogma is the flow of information
from ……………………..to …………………….
•The main purpose of central dogma is to
synthesize ………………………….
•Central dogma includes three stages they
are……………., …………..and …………………
• DNA replication is to make …………………………
• DNA transcription is to make ………..............from
………………….
• In prokaryotes such as bacteria both processes
occur in the ……………….,since they do not have
…………………………..
In eukaryotes like animals, humans, and plants the
processes occur in the …………………………….
•Transcription process resulted in
……………types of ………………they are
•1- ……………………………………..
•2- ……………………………….
•3- …………………………………….
•m RNA stands for ……………………………….
•Its function is to …………………………………
•t RNA stands for ………………………………..
•Its function is to ……………………………………
•r RNA stands for …………………………………
•Its function is to ……………………………………
DNA NEEDS RNA!
RNA is a nucleic acid
messenger between
DNA and ribosomes
That is why DNA is
transcribed into RNA
HOMEWORK 1
Does this
diagram
represent
DNA or RNA?
…how can
you tell?
TRANSLATION PROCESS
• To understand the meaning of
translation, pay attention.
• What do these Chinese
• symbols say?
Transcribe to English alphabet:
Translate to English words:
• Recall that:
•The DNA molecule
contains all your
hereditary information
in the form of genes
•A gene is a coded
section of DNA; it tells
our cells how to build
specific proteins
• Genes code for EVERYTHING our body needs and
does (saliva, bones, eye shape)….our traits….
• Because DNA is so large, it is stuck inside the
nucleus
• It needs a messenger to move the information
from the nucleus to protein production locations
(ribosomes! That are found in the cytoplasm)
TRANSLATION PROCESS ……………..
•Translation converts
mRNA messages into
polypeptides/proteins
For genius students…
•Why especially mRNA?
YOU ARE A
TRANSLATION PROCESS
• RNA (m RNA) is formed from DNA. It carries the
code to form a certain protein.
• a protein is made up of units called amino acids.
• Amino acids are coded by mRNA base sequences.
• A codon is a sequence of three nucleotides that
codes for an amino acid.
EVERY 3 NUCLEOTIDES MAKE A CODON WHICH
CODES FOR AN AMINO ACID
HOMEWORK 2
How many
nucleotides form
one codon?
TRANSLATION PROCESS INVOLVED….
– reading the mRNA code
- assembling amino acids
into a polypeptide chain
(protein)
•Each codon is
matched to an
anticodon, or
complementary
sequence on the
tRNA to determine
the order of the
amino acids
• An anticodon is a
set of three
nucleotides that is
complementary
to an mRNA
codon.
• An anticodon is
carried by a
tRNA.
DECODING MRNA (TRANSLATION)
•The sequence of bases in an mRNA molecule
serves as instructions for the order in which
amino acids are joined to produce a
polypeptide
•Ribosomes decode the instructions by using
codons, sets of 3 bases that each code for 1
amino acid
• Ribosomes
consist of two
subunits.
• The large
subunit has three
binding sites for
tRNA.
• The small
subunit binds to
mRNA.
•Translation occurs in ribosomes
(in the cytoplasm)
•All three types of RNA work
together during translation to
produce proteins
• For translation to begin, tRNA binds to a start codon and signals
the ribosome to assemble.
• A complementary tRNA molecule binds to the exposed codon,
bringing its amino acid close to the first amino acid.
• The ribosome helps form a polypeptide bond between the amino acids.
• The ribosome pulls the mRNA strand the length of one codon.
• The now empty tRNA molecule exits the ribosome.
• A complementary tRNA molecule binds to the next exposed codon.
• Once the stop codon is reached, the ribosome releases the protein and
disassembles.
USING A CODON CHART
•A codon chart is used to determine
the sequence of the amino acids in
the polypeptide
•The sets of 3 mRNA bases (codons)
are used to find the amino acid
DECODING PRACTICE
• Example 1:
• DNA:
TAC GCA TGG AAT
• mRNA:
AUG CGU ACC UUA
Amino Acids: Met Arg
Thr
Leu
HOMEWORK 3
Predict the sequence of the
amino acids that are coded
by this DNA
DNA: CGT GGA GAT ATT
PROBLEMS IN TRANSLATION
•A change in the
order in which
codons are read
changes the
resulting
protein.
Regardless of the organism,
codons code for the same amino
acid.
END OF LS 8.5