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Bellringer


Please answer on your bellringer sheet:
Replicate the following DNA sequence
 AGGTATCAG

Please add questions (at least 2 questions per
page) and a summary to your DNA Replication
Mutation Notes
3
things you learned
 2 things you found interesting
 1 question you still have
Learning Targets (write at the top of
your notes)





Compare and contrast the structures and functions
of DNA and RNA.
Describe the steps of transcription in synthesizing a
protein.
Explain how mRNA can be modified through the
process of splicing.
Describe the steps of translation in synthesizing a
protein.
Describe the structure of a protein and the functions
carried out by proteins in the cell.
RNA AND PROTEIN
SYNTHESIS
The Plan…

How does DNA control cell activities if it can’t leave
the nucleus?
 It


sends a messenger! - messenger RNA (mRNA for short)
Remember, DNA (which remember DNA makes up
your genes) contains the code for making proteins.
DNA can’t leave the nucleus, so RNA has to help out
and actually make the proteins on the ribosomes.

Ribonucleic Acid


Ribonucleic acid (RNA)
What makes up a nucleotide?
- molecule that controls
the production of
proteins for cells.
A strand of RNA is made
of repeating units
(monomers) called
nucleotides (like DNA)
RNA vs. DNA
Three differences between
RNA and DNA:
 Single-stranded
 Ribose
instead of
Deoxyribose
 Uracil instead of Thymine

Checkpoint: RNA vs. DNA
DNA
Double strand
 Deoxyribose
 Contains Thymine
 Stays in nucleus

RNA
Single Strand
 Ribose
 Contains Uracil
 Leaves nucleus


Types of RNA

Messenger RNA (mRNA)
 single,
uncoiled strand
 serves as pattern for assembly of amino acids

Transfer RNA (tRNA)
 carries
amino acids to the
ribosome
 single stranded

Ribosomal RNA (rRNA)
 globular
form
 makes up the structure of the ribosome



Transcription
Process of making mRNA from a
single–strand of DNA.
The nitrogen bases in RNA always
bond to their complement on the
DNA strand


ADENINE binds to URACIL
GUANINE binds to CYTOSINE

Steps in Transcription
1.
2.
3.
The enzyme RNA polymerase “unzips” the
complementary strands of DNA into two single
strands.
RNA nucleotides bond to a single strand of DNA
The finished mRNA is released and the two DNA
strands “re-zip”
Steps in Transcription
Adenine (DNA and RNA)
Cystosine (DNA and RNA)
Guanine(DNA and RNA)
Thymine (DNA only)
Uracil (RNA only)
RNA
polymerase
DNA
RNA
Transcription animation

mRNA Splicing
AUGGGCAUUAGCCUA

Enzymes remove (cut out)
introns because they interrupt
the coding sequence
• INTRONS INTERRUPT … INTRONS OUT !!!
• Exons are left behind to be “expressed” (translated) as needed
proteins
Again...
unit of transcription in a DNA strand
exon
intron
exon
transcription
mRNA
snipped
out
intron
into pre-
snipped
out
mature mRNA transcript
exon

Checkpoint!

Transcribe the DNA strand into RNA:
TAC TCG TCC ATA GGC ATC
AUG AGC UGG UAU CCG UAG

Protein Synthesis


Bases in mRNA code for
the amino acids which
will make a functioning
protein.
A group of three
sequential bases on an
mRNA strand is a
CODON.

The Genetic Code


There are a possible 64 CODONS that code for 20
AMINO ACIDS and a START/STOP SIGNAL.
The genetic code is universal among all organisms.
The Genetic Code
First Base
Second Base
U
UUU
U
C
UUC
Phenylalanine
UUA
Leucine
UCC
UCA
Serine
UAC
UAA
UCG
UAG
CUU
CCU
CAU
CUC
CCC
CAC
CUA
Leucine
CCA
Proline
CAA
CUG
CCG
CAG
AUU
ACU
AAU
ACC
AAC
Isolecine
Threonine
G
Tyrosine
Stop
Histidine
Glutamine
Aspargine
UGC
Stop
UGG
Tryptophan
CGU
CGC
CGA
AGU
AAG
Lysine
AGG
GCU
GAU
Aspartic
Acid
GGU
GUG
Valine
GCC
GCA
GCG
Alanine
GAC
GAA
GAG
Serine
AGC
ACG
GUA
Arginine
CGG
AUG
GUC
Cysteine
UGA
ACA
Start & Methionine
AAA
UGU
AUA
GUU
G
A
UAU
UUG
AUC
A
C
UCU
AGA
Glutamic Acid
Arginine
GGC
GGA
Glycine
GGG
mRNA strand – G C A A C G U U G C U A C U G
Amino Acids – Alanine - Threonine - Leucine Leucine - Leucine -

Steps in Translation

1.
2.
Process of using RNA to assemble amino acids into
proteins.
mRNA moves out of the nucleus and attaches to
ribosome.
tRNA transports amino acids to the ribosome.
Steps in Translation

Steps in Translation
3.
4.
5.
The anticodon on tRNA bonds to the
complementary codon on mRNA.
Amino acids form peptide bonds and form a
strand – a polypeptide.
The stop codon on mRNA ends the process and the
new protein is released.
Steps in Translation
Translation animation
Your Turn!
Be A Ribosome …
Translate your codons
into amino acids using the codon chart
on the next slide:
AUGCAUAGCCUA
Met
Protein Synthesis Video
His
Ser
Leu
Codon Chart