Download 10.6-10.16 Genetic Information from DNA to RNA to Protein

 The
central concept
in biology is:
 DNA
determines what
protein is made
 RNA takes instructions
from DNA
 RNA programs the
production of protein
synthesis
 Proteins determine
the phenotype of the
organism
 Proteins
are
made into two
main stages


Transcription- the
transfer on genetic
info from DNA to
RNA molecule
Translationtransfer of info in
the RNA into a
protein
 What
is a protein?
 What protein have you eaten today
and/or yesterday?
 What role do proteins play in your
bodily functions?
mRNA Codon Chart
 Genes
are located on
molecules of DNA
 The language of DNA is
the order (sequence) of
nucleotides

Ex: AAGCTT
 The
order of the
nucleotides determine
which genes are made
 DNA’s
instructions are
based on 3
nucleotides (triplet
code)
 The 3 nucleotide
sequence (codon) are
the genetic
instructions from DNA
to make amino acids;
which together make
polypeptide chains
(proteins)
 Each
codon specifies for an amino acid
A close-up view of transcription
 During
1.
transcription:
RNA polymerase (an enzyme)binds to
DNA on the promoter region & separates
the DNA strands.

Promoter- Region of DNA (a codon) that
allows transcription to begin

Terminator- Region of DNA that signals
the end of a gene & transcription stops.
•

There are 3 main types of RNA:
• Messenger RNA (mRNA)– carry copies
instructions from genes for putting together
amino acids into proteins. Carry
“messages” from DNA to the rest of the
cell.
•
Ribosomal RNA (rRNA)- makes up a
major part of the ribosome (proteins
are put together here)
True shape of a functioning ribosome
•
Transfer RNA (tRNA)- transfers each
amino acid to the ribosome as it is
specified by coded messages in mRNA.
•
When RNA molecules are
formed, introns and exons
are copied from DNA.
•
Introns- DNA sequences of
nucleotides that do not
code for a protein
Exons- sequences that does
code for a protein
The introns are cut out of
RNA molecules.
The exons are then spliced
together to form mRNA.
•
•
•
•
•
1.
2.
3.
Takes place on the ribosomes
Translation- the decoding of an mRNA message
into a polypeptide chain (protein)
Translation begins when an mRNA molecule
attaches to a ribosome.
As each codon of the mRNA molecule moves
through the ribosome, the proper amino acid is
brought into the ribosome by tRNA.
In the ribosome, the amino acid is transferred
to the growing polypeptide chain.
•
•
•
In the process anticodons are formed
Anticodon- 3 unpaired bases of tRNA that are
complementary to mRNA
 Are
made of rRNA
 Have
a binding site for mRNA and three binding sites
for tRNA molecules

The P site holds the tRNA carrying the growing
polypeptide chain

The A site carries the tRNA with the next amino acid

tRNAs leave the ribosome at the E site
1) Initiation
brings together mRNA, with tRNA
Special initiator tRNA carries and attaches to the start
codon
2)Elongation
adds amino acids according
to the mRNA codons
 Peptide
bond formation b/w a.a’s
 During translocation, the ribosome moves
the tRNA with the attached polypeptide
from the A site to the P site
 Elongation continues codon by codon to add
amino acids until the polypeptide chain is
completed
3) Termination
occurs when one of the three stop
codons reaches the A site
 Errors
can occur during DNA
replication, DNA repair, or DNA
recombination
 These can lead to base-pair
substitutions , insertions , or
deletions
 Can lead to frame shifts, which
move the reading frame over
slightly and change the primary
structure of the polypeptide
 Are
chemical or physical agents that
interact with DNA to cause
mutations
 Physical agents include high-energy
radiation like X-rays and ultraviolet
light
 Chemical agents include
carcinogens cause cancer