Download RNA Protein Synthesis (chap 13) notes

RNA and PROTEIN SYNTHESIS
Chapter 13-1 & 13-2
© Pearson Education Inc, publishing as Pearson Prentice Hall. All rights reserved
DNA’s code is used to make proteins,
right?
Does DNA work alone?
• Check out where DNA
holds the code?
• Check out where
proteins are made?
• So what other
molecule is needed?
A. RNA- the Other Nucleic Acid
• Also made of NUCLEOTIDES
• Sugar is RIBOSE instead
of deoxyribose.
• RNA is SINGLE stranded
• Contains URACIL (U) instead
of thymine.
http://images2.clinicaltools.com/images/gene/dna_versus_rna_reversed.jpg
B. KINDS OF RIBONUCLEIC ACID (RNA)
1. Ribosomal RNA (rRNA)
-Combines with proteins to form ribosomes
2. Transfer RNA (tRNA)
-Matches mRNA codon to add correct
amino acids during protein synthesis
3. Messenger RNA (mRNA)
-Carries code from DNA to ribosomes
rRNA and t-RNA images from © Pearson Education Inc, publishing as Pearson Prentice Hall. All rights reserved
mRNA image from http://wps.prenhall.com/wps/media/tmp/labeling/1140654_dyn.gif
C. Transcription – the process of making
RNA from DNA
Adenine (DNA and RNA)
Cystosine (DNA and RNA)
Guanine(DNA and RNA)
Thymine (DNA only)
Uracil (RNA only)
Section 12-
RNA
polymerase
RNA
DNA
1. An enzyme, RNA polymerase,begins
transcription by binding to promoters (like
the ‘starting line’)
2. The two strands of DNA are separated
3. Complementary RNA nucleotides are
added to one strand (called the template)
of DNA
4. When RNA polymerase reaches the
termination signal, transcription ends.
5. The RNA is released through the
nucleus and DNA reforms.
http://images2.clinicaltools.com/images/gene/dna_versus_rna_reversed.jpg
See a video clip about
TRANSCRIPTION
(mcgraw-hill animation)
RNA’s require EDITING before use
Image by Riedell
D. Protein Synthesis –
genetic info from
DNA is used to make proteins in two steps
1. TRANSCRIPTION (DNA→ RNA)
takes place in nucleus
2. TRANSLATION (RNA→ proteins)
takes place on ribosomes in cytoplasm
http://www.home-improvement-resource.com/images/architect.jpg
E. Why are proteins important?
• Proteins determine the structure &
function of the cell.
• Proteins are made up of one or more
polypeptides, each of which consists of a
specific sequence of amino acids
F. HOW CAN JUST 4 BASES GIVE
DIRECTIONS TO MAKE 20 AMINO ACIDS?
• Message is read in groups of 3 = CODON
example:
UCGCACGGU
UCG-CAC-GGU
Serine - Histidine - Glycine
- Codons represent different
AMINO ACIDS
G
G. The Genetic Code
- used by most organisms to translate
mRNA transcripts into proteins
• 64 possible codons
• Some amino acids
have more than one
codon.
• START= AUG
• 3 codons for STOP
• ANTICODON
on tRNA
• EACH tRNA
carries only
one kind of
AMINO ACID
• matches up with
CODON
on mRNA
Images modified from © Pearson Education Inc, publishing as Pearson Prentice Hall. All rights reserved
H. Translation - process where amino acids
are assembled into polypeptides
1. mRNA leaves nucleus & attaches to a ribosome
2. The start codon (AUG) on mRNA allows its
complementary anticodon on tRNA to move in
3. A ribosome can hold another ‘codonanticodon’ pairing so the two amino acids are
linked by a peptide bond
4. Then ribosome slides down mRNA to ‘read’
next codon and repeats the process
5. The polypeptide (a chain of amino acids) is
complete when a stop codon is reached
I. Ribosomes
• those that are free in cytoplasm produce
proteins that will be used within cell.
J. Endoplasmic reticulum (ER)
• proteins that are
exported outside cell
are produced by
ribosomes attached
to the ER
Video 4
See a video clip about
PROTEIN SYNTHESIS
TRANSLATION VIDEO (Choose Large video)
• DNA → DNA REPLICATION
____________
The Central Dogma Of Biology
DNA  RNA  Proteins
TRANSCRIPTION
• DNA → RNA ____________
TRANSLATION
• RNA→ Protein ___________
Mendel/flower images from: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookTOC.html
Blood cell by Riedell
GENES & PROTEINS
Proteins are the connection between
the gene code in the DNA and how that
gene is expressed.
A gene that codes for an enzyme (protein)
to make a pigment can control
the color of a flower.
A gene that codes for an enzyme (protein)
adds carbohydrates to glycoproteins to
produce your blood type.
Enzymes catalyze and regulate chemical reactions so
proteins build and operate all cell components.