A ribosome; where proteins are made
1. RNA is a nucleic acid
2. RNA is made of:
a) long chains of nucleotides
b) Ribose sugar
c) Single-stranded
d) Has a nucleotide called Uracil instead of Thymine
e) The nucleotides are Adenine, Uracil, Guanine, &
Cytosine
f) Guanine bonds w/ cytosine, & adenine bonds w/
uracil
3. An RNA molecule
is a working copy
of a single gene
4. Genes- coded
DNA instructions
that control the
making of
proteins w/i the
cell
DISCUSSION REVIEW QUESTIONS:
1. What is a protein?
2. List the protein you ate today and/or
yesterday
3. What role do proteins play in your body
functions?
ANSWERS:
1. What is a protein? A macromolecule that is
formed by many amino acids that are linked
together
2. List the protein you ate today and/or
yesterday Chicken, Beef, Fish, Lamb, dairy
products, beans, and nuts
3. What role do proteins play in your body
functions? Needed by the body for growth,
repair, movement, immune response, to
make up enzymes, etc.
1. There are 3 main types of RNA:
a) Messenger RNA (mRNA)– carries copies of
instructions from genes (DNA) for putting
together amino acids into proteins.
 Carries “messages” from DNA to the rest of
the cell.
 Is transcribed from genes that encode proteins
b) Ribosomal RNA (rRNA)makes up a major part
of the ribosome
 proteins are put
together here
 Binds to other proteins
in the cytoplasm before
it is activated
 Has a way to decode
mRNA into amino acids
and interacts with tRNA
during translation
c) Transfer RNA
(tRNA)- transfers
each amino acid to
the ribosome as it is
determined by the
coded messages in
mRNA.
 Binds to other
proteins in the cell
before it is activated
DISCUSSION W/ PARTNER:
Page . 301 figure 12-14
1. Where is DNA located in the eukaryotic cell?
2. Where does transcription take place?
3. Where does protein synthesis take place?
ANSWERS:
1. Where is DNA located in the eukaryotic
cell? In the nucleus of the cell
2. Where does transcription take place? In
the nucleus
3. Where does protein synthesis take place?
In the cytoplasm of the cell
IN YOUR NOTEBOOK
Page 301 figure 12-13
1. What are the two main regions of a
ribosome?
2. Each letter on the ribosome
represents a different protein; how
many proteins are on a ribosome?
ANSWERS:
1. What are the two main regions of a
ribosome? 30S and 50S, mRNA brings
codons b/w these two regions during
translation
2. Each letter on the ribosome represents
a different protein; how many proteins
are on a ribosome? 6
1. RNA Polymerase- an
enzyme that binds to
DNA & separates the
DNA strands during
transcription
2. Promoters- A specific
DNA nucleotide
sequence where mRNA
starts transcription
RNA polymerase only
connects to the
“promoter” region of
DNA
3. Transcription- RNA molecules are made by copying
a part of the nucleotides from a DNA sequence
4. Transcription happens when:
a) RNA polymerase connects to DNA &
separates the DNA strands.
b) RNA polymerase then uses one strand of DNA
as a template to put together nucleotides into a
strand of RNA.
TRANSCRIPTION
TRANSCRIBE THE FOLLOWING FROM
DNA TO mRNA
DNA strand:
AAT GCT GCG GAT
RESULTS OF TRANSCRIPTION FROM DNA
TO mRNA:
DNA codon: AAT GCT GCG GAT
mRNA codon: UUA CGA CGC CUA
1. Introns- DNA sequences of
nucleotides that do not
code for a protein
2. Exons- sequences that
does code for a protein
a) The introns are cut out of
RNA molecules.
b) The exons are then spliced
together to form mRNA.
c) They are expressed in the
production or synthesis of
proteins
DISCUSS W/ PARTNER:
Contrast introns and exons.
ANSWER:
• Contrast introns and exons.
Exons code for proteins and
introns do not code for proteins
1. Is universal in all organisms
2. Proteins are made by putting together a
lot of polypeptides.
3. Polypeptides -a combination of any or all
20 amino acid molecules.
• The order of the amino acid determines
the characteristic of the protein
4. mRNA’s language is
called the genetic
code which is 3
“letters” transcribed
from DNA.
5. The code is written
using four “letters”
(the bases: A, U, C,
and G
6. Codon -three nucleotides that are next to
each other on mRNA that determine a
particular amino acid
THE GENETIC CODE
IN YOUR NOTEBOOK:
1. For what amino acid does
the mRNA codon ACA code?
ANSWER:
1. For what amino acid does
the mRNA codon ACA code?
Threonine
1. Takes place on the
ribosomes
2. Takes place after
transcription (DNA to
mRNA)
3. The cell uses info from
mRNA to produce
proteins.
4. Translation- the decoding
of an mRNA message
into a polypeptide chain
(protein)
A ribosome and tRNA molecules work together to
translate a mRNA molecule. The growing amino
acid chain will become a protein.
Credit: National Human Genome Research
Institute
5. Translation begins
when an mRNA
molecule attaches
to a ribosome.
6. The ribosome
binds new tRNA
molecules and
amino acids as it
moves along the
mRNA
Ribosome
start codon
mRNA
7. As each codon of the
mRNA molecule moves
through the ribosome,
the proper amino acid is
brought into the
ribosome by tRNA.
8. In the ribosome, the
amino acid is transferred
to the growing
polypeptide chain
B. Transfer RNA
9. In the process anticodons are formed
10.Anticodon- 3 unpaired bases of tRNA that are
complementary to mRNA
• The DNA codon is what gets transcribed and translated
into an amino acid.
C. The Polypeptide “Assembly Line”
11. The ribosome forms
a peptide bond b/w
the amino acids.
12.The ribosome also
breaks the bond b/w
tRNA & it’s amino
acid; the tRNA
molecule is released
D. Completing the Polypeptide
Stop Codon
13.The polypeptide chain
grows until a “stop”
codon on mRNA is
reached
14. Both the mRNA & the
new polypeptide chain
are released, ending the
translation process.
15.The polypeptide will form
a protein.
16.The sequence of bases
in DNA is used as a
template for mRNA.
17.The codons of mRNA
specify the sequence of
amino acids in a protein.
TRANSCRIBE & TRANSLATE THE FOLLOWING
mRNA CODON TO AMINO ACIDS
DNA codon:
mRNA codon:
AAT GCT GCG GAT
UUA CGA CGC CUA
ANSWERS
DNA codon
AAT
mRNA codon UUA
tRNA anticodon: AAU
Amino Acid s :
Leucine
GCT
GCG
GAT
CGA
CGC
CUA
GCU GCG
GAU
Arginine Arginine Aspartic Acid
The protein is made from mRNA’s codon
1. DNA stays safely
inside the nucleus
2. RNA molecules go to
the ribosomes which
are the protein
building cites inside
the cytoplasm
1. Genes are tools
which are each
specifically designed
to build or operate a
part of a living cell.
 A gene the codes for an
enzyme to produce a certain
pigment determines the color
of a flower
 A gene produces an enzyme
that produced red blood cell
surface antigen; this
determines your blood type.