Download 12.3 DNA, RNA, and Protein Molecular Genetics

Protein Synthesis
Georgia Performance Standards:
SB2. Students will analyze how biological traits are
passed on to successive generations.
a. Distinguish between DNA and RNA.
b. Explain the role of DNA in storing and transmitting cellular
information.
Essential Questions:
EQ: How does the cell make protein?
EQ: Why do you need DNA and RNA?
EQ: What do proteins have to do with the genetic
traits?
Nucleic Acid Review
• DNA: Deoxyribonucleic
Acid
• Double Helix
– explains how DNA can
be replicated
– does not explain how
a gene works.
• Nucleus (eukaryote)
• Cytoplasm (prokaryote)
• DNA Polymerase
• Deoxyribose Sugar
• PO4-3 group
• Nitrogenous base
– Adenine
– Thymine
– Cytosine
– Guanine
Nucleic Acid Review
• RNA: Ribonucleic
Acid
• Single stranded
• In cytoplasm
• RNA Polymerase
• mRNA (codon)
• tRNA (anticodon)
• rRNA
• Ribose sugar
• PO4-3 group
• Nitrogenous base
–
–
–
–
Adenine
Uracil
Cytosine
Guanine
Chapter
12
Molecular Genetics
12.3 DNA, RNA, and Protein
Central Dogma: DNA  RNA Protein
 RNA
 Contains the sugar ribose and the
base uracil
 Usually is single stranded
Chapter
12
Molecular Genetics
12.3 DNA, RNA, and Protein
Messenger RNA (mRNA) = the codon
 Long strands of RNA nucleotides that are formed
complementary to one strand of DNA
Ribosomal RNA (rRNA)
 Associates with proteins to form ribosomes in the
cytoplasm
Transfer RNA (tRNA) = the anticodon
 Smaller segments of RNA nucleotides that
transport amino acids to the ribosome
Chapter
12
Molecular Genetics
12.3 DNA, RNA, and Protein
Concept Map
Section 12-3
RNA
can be
Messenger RNA
also called
mRNA
(Codon)
Go to
Section:
Ribosomal RNA
which functions to
also called
Carry instructions
rRNA
which functions to
Combine
with proteins
from
to
to make up
DNA
Ribosome
Ribosomes
Transfer RNA
also called
tRNA
(anticodon)
which functions to
Bring
amino acids to
ribosome
Chapter
12
Molecular Genetics
Chapter
12
Molecular Genetics
12.3 DNA, RNA, and Protein
Transcription
 Through
transcription, the
DNA code is
transferred to mRNA
in the nucleus.
 DNA is unzipped in the
nucleus and RNA
polymerase binds to a specific section where an
mRNA will be synthesized.
Chapter
12
Molecular Genetics
12.3 DNA, RNA, and Protein
RNA Processing
 The code on the DNA is interrupted
periodically by sequences that are not in the
final mRNA.
 Intervening sequences are called introns.
 Remaining pieces of DNA that serve as the
coding sequences are called exons.
DNA and
Genes
Chapter
12
Molecular Genetics
12.3 DNA, RNA, and Protein
The Code
 Experiments during the 1960s
demonstrated that the DNA code was a
three-base code.
 The three-base code in DNA or mRNA is
called a codon.
Chapter
12
Molecular Genetics
12.3 DNA, RNA, and Protein
Translation
 In translation, tRNA
molecules act as the
interpreters of the mRNA
codon sequence.
 At the middle of the folded
strand, there is a threebase coding sequence
called the anticodon.
 Each anticodon is
complementary to a codon
on the mRNA.
Molecular Genetics
Chapter
12.3 DNA, RNA, and
12
Protein
Chapter
12
Molecular Genetics
Chapter
12
Molecular Genetics
12.3 DNA, RNA, and Protein
One Gene—
One Enzyme
 The Beadle and
Tatum experiment
showed that one gene
codes for one
enzyme. We now
know that one gene
codes for one
polypeptide.
Protein Synthesis Overview:
• Genes are sequences
of DNA that code for
the production of
proteins in the cell.
– mRNA (codon) enters
the nucleus
– RNA polymerase
copies part of the
nucleotide sequence
from DNA into RNA
(transcription)
• DNA: CCC-TAG-GATGTA-CGC
• mRNA: GGG-AUCCUA-CAU-GCG
• Video Clip
Protein Synthesis Overview:
– mRNA goes through
the nuclear pores to
take that copy to the
ribosome, which is in
the cytoplasm.
• mRNA: GGG-AUC-CUA-CAU-GCG
• tRNA: CCC-UAG-GAU-GUA-CGC
• Glyine-Isoleusine-Leucine-HistidineAlanine
– tRNA (anticodon)
reads the mRNA
• Video Clip
(codon) and transfers
amino acids to make
proteins (translation)
Sequence of Events:
1. Initiation:
– RNA polymerase binds to the promoter region on
DNA.
– tRNA binds to a specific start codon (AUG) on mRNA
while transferring methionine to the AUG codon
– Ribosome binds to the mRNA
2. Elongation: explained later
3. Termination: explained later
Elongation:
• The ribosome joins amino acids together
through peptide bonds.
• The ribosome moves along the mRNA
binding new tRNA and amino acid
molecules.
Termination:
• The process continues until the ribosome
reaches one of the three stop codons.
– UGA
– UAG
– UAA
The Genetic Code:
• Because there are four different bases, there are
64 possible three-base codons (4 × 4 × 4 = 64).
• Some amino acids can be specified by more
than one codon.
• For example, six different codons specify the
amino acid leucine, and six others specify
arginine.
The Genetic Code
The Big Picture…
• What do proteins have to do with genetic traits?
– Proteins=enzymes=catalyze and regulate chemical
reactions.
– Gene=codes for an enzyme=produce pigmentation
– Genes=code for proteins=regulate the rate and
pattern of growth
– DNARNAProteins= control all cellular processes
Check for Understanding:
1. List the three main types of
RNA.
2. What happens during
transcription?
3. What happens during
translation?
4. Describe three main
differences between RNA and
DNA.
5. Using the genetic code,
identify the amino acids that
have the following messenger
RNA strand codes:
UGGCAGUGC.
Descriptive Writing (Alternate)
• An RNA molecule is looking for
a job in a protein synthesis
factory, and it asks you to write
its résumé.
• This RNA molecule is not yet
specialized and could, with
some structural changes,
function as either mRNA,
tRNA, or rRNA.
• The résumé you create should
reflect the qualifications
needed for each type of RNA.
Protein Synthesis
Georgia Performance Standards:
• Compare and contrast the structure and function of
DNA and RNA
• Explain the role of DNA in storing and transmitting
cellular information
Essential Questions:
EQ: How does the cell make protein?
EQ: Why do you need DNA and RNA?
EQ: What do proteins have to do with the
genetic traits?
Warm-up (Choose one):
• Choice 1: Venn
diagram
– Compare and
contrast DNA and
RNA.
– Indicate location,
structure, &
function
• Choice 2: Descriptive Writing
• An RNA molecule is looking for a
job in a protein synthesis factory,
and it asks you to write its
résumé.
• This RNA molecule is not yet
specialized and could, with some
structural changes, function as
either mRNA, tRNA, or rRNA.
• The résumé you create should
reflect the qualifications needed
for each type of RNA.
Formative Assessment Review
• Below, you are given a DNA sequence. Transcribe the
correct mRNA (codon) sequence. Use the genetic code
to determine the correct tRNA (anticodon) sequence.
Translate the correct amino acid sequence from the
mRNA codon.
• Hints: DNA (A-T and G-C)RNA (A-U and G-C)
• The codon codes for the amino acid sequence
DNA = GGG-ATC-CTA-CAT-GCG
mRNA (codon) =
tRNA (anticodon) =
Amino Acids =
RIBOSOME GAME
DNA =CTA-CTG-GTG-CTT-CTC-CGA-CGG-CGT-TTA-TTTCCC-GCG-GTG-CTT
mRNA = GAU-GAC-CAC-GAA-GAG-GCU-GCC-GCA-AAUAAA-GGG-CGC-CAC-GAA
tRNA =CUA-CUG-CUC-CUU-CUC-CGA-CGG-CGU-UUA-UUUCCC-GCG-GUG-CUU
AMINO ACIDS= ASP-ASP-HIS-GLU-GLN-GLU-ALA-ALA-ASNLYS-GLY-ARG-HIS-GLU
Word Wall:
• Protein
• DNA
polymerase
• RNA
polymerase
• Plasmid
• Chromosome
• mRNA
• tRNA
• rRNA
• Promoter
• Initiation
• Avery
• Hershey &
Chase
• Prokaryote
• Eukaryote
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Deoxyribose sugar
Adenine
Guanine
Thymine
Cytosine
Uracil
Gene
Chargoff
Single stranded
Cytoplasm
Nucleus
Double helix
Termination
Griffith
Ribose Sugar
•Watson & Crick
•Rosalind Franklin
•Transformation
•Base pairing
•Nucleotide
•Chromatin
•Histone
•Replication
•Transcription
•Translation
•Codon
•Anticodon
•Phosphate
•Elongation