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RNA AND
TRANSCRIPTION
Biology
CHUMS
RNA
 RNA
= Ribonucleic Acid
 Function of RNA: To carry the DNA’s
code out of nucleus to make proteins
 3 Parts of RNA
 Sugar:
Ribose
 Phosphate group,
 Nitrogen base
(sound familiar???)
Break Out! #1
 What
organelle is responsible for
making protein?
o
Ribosomes
 Fact
or Fiction: All living things have
ribosomes to make protein?
o
Fact!!! – Even bacteria has ribosomes!!
 What
are proteins made of? (what are
their building blocks?)
o
Amino Acids
What’s the Difference??

3 main differences
between DNA and RNA
1.
Sugar in RNA is ribose
2.
RNA is single-stranded
3.
RNA contains uracil (U)
in place of thymine (T).
***RNA can leave the
nucleus***
Types of RNA (oh there’s more than one…)
1.
Ribosomal RNA (rRNA) = major
component of ribosomes
 Ribosome:
structure where proteins
are assembled.
Types of RNA (continued)
Messenger RNA (mRNA) = RNA that
carries the instructions or codons for
assembling amino acids into proteins.
2.

Leaves nucleus and enters cytoplasm to attach
to a ribosome when done!
Types of RNA (continued)
3.
Transfer RNA (tRNA) = RNA that carries
the anticodon to transfer or bring each
amino acid to the ribosome
 Complementary
code to mRNA
Transcription: Makin’ some mRNA
 Occurs
 DNA
1.
2.
3.
4.
in the nucleus
mRNA
Enzyme unzips the DNA strand
One open strand of DNA is a template to
make a strand of mRNA.
When the mRNA is done being coded, it
leaves the nucleus to find a ribosome to
start building proteins
DNA “re-zips” back to normal.
Transcription Rules
DNA
must stay in the nucleus
DNA unzips at a starting code
 DNA
= TAC
mRNA = ___________
Break Out! #2
 Make
some mRNA!
 Use the template below to make some mRNA
from the template of DNA. Remember to sub in
the correct complementary pairs for RNA!
Original DNA Strand
Template DNA Strand
G-C
G
T-A
T
A-T
A
A-T
A
G-C
G
C-G
C
Biology
Cardinal Heights
Translation:
• When ribosomes read mRNA
(messenger) and use the sequence to
make proteins.
• Proteins are made by joining
amino acids into long chains.
 There
are 20 different amino acids
A
codon consists of three consecutive
nitrogen bases of mRNA that codes a
single amino acid.
 Example:
UCG CAC GGU
 Divide
the following sequence of mRNA
into segments of codons by drawing lines
in between every 3rd base pair.
AUGUACUUUGACGGAUGA
How do you
know which
Amino Acid
mRNA is
coding for?
 Below
your strand of mRNA (that you just
divided), find the correct amino acid for
each codon, using the codon wheel.
 Write the first three letters of the amino
acid under its codon.
AUGUACUUUGACGGAUGA
MET TYR PHE ASP GLY STOP
START
mRNA serves as
the instructions
Codons are read
by a ribosome
1.
2.
•
Starts at AUG (“Start”
Codon)
3.
tRNA (transfer RNA) has the anticodon
(complementary base pairs to mRNA).
4.
tRNA transfers the correct amino acid
to the ribosome for assembly of the
protein
Ribosomes will move down the mRNA,
holding two codons of mRNA at a time.
5.
•
Each tRNA bumps off the previous
one, leaving the strand of amino acids
behind.
What
A
is a chain of Amino Acids?
PROTIEN
When
 When
 Just
does the chain end?
it hits a STOP codon
like there is a start codon, there is
also a stop
Let’s Watch!