Download Protein Synthesis Notes

Griffith’s Experiments
Study suggested that DNA was
probably the genetic material
http://nortonbooks.com/college/biology/ani
mations/ch12a01.htm
http://www1.teachertube.com/viewVideo.ph
p?video_id=113347&title=History_of_DNA
Hershey and Chase Experiments
Radioactive
bacteria!
32P
was injected into
Hershey & Chase proved that DNA was the
cell’s genetic material!
http://highered.mcgrawhill.com/sites/0072437316/student_view0/chapt
er14/animations.html
Protein coat labeled
with 35S
Hershey
&
Chase
T2 bacteriophages
are labeled with
radioactive isotopes
S vs. P
bacteriophages infect
bacterial cells
bacterial cells are agitated
to remove viral protein coats
Which
radioactive
marker is found
inside the cell?
Which molecule
carries viral
genetic info?
DNA labeled with 32P
35S
radioactivity
found in the medium
32P
radioactivity found
in the bacterial cells
Chargaff
Discovered that amts of Adenine = Thymine, and Guanine = Cytosine
James Watson and Francis Crick
Double helix …..held together by hydrogen bonds
•
•
•
•
•
DNA
1. Sugar deoxyribose
2. Phosphate
3. Nitrogen base
-thymine
RNA
1. Sugar ribose
2. Phosphate
3. Nitrogen base
-uracil
Base Pairing
DNA
Thymine (T) – Adenine (A)
PYRIMIDINE
PURINE
Guanine (G) – Cytosine (C)
PURINE
T
A
G
C
PYRIMIDINE
Weak hydrogen bonds
T or C
A or G
DNA
5
O
3
3
P
5
O
O
C
G
1
P
5
3
2
4
4
P
5
P
2
3
1
O
T
A
3
O
3
5
O
5
P
P9
Base Pairing
RNA
Uracil (U) – Adenine (A)
PYRIMIDINE
PURINE
Guanine (G) – Cytosine (C)
PURINE
PYRIMIDINE
U
A
G
C
1.
DNA unzips (hydrogen bonds between the nitrogen
bases are broken by enzymes).
2.
Free nucleotides pair with exposed bases. DNA
Polymerase bonds the nucleotides together.
3. Two identical double stranded DNA molecules are
formed. (ClassZone)
http://nortonbooks.com/college/biology/
animations/ch12a04.htm
• 1. RNA is single stranded DNA is double
• 2. RNA can leave the nucleus and enter
the cytoplasm DNA can not.
• 3. RNA has the sugar ribose, DNA has
the sugar deoxyribose
• 4. RNA- uracil, DNA- thymine
http://highered.mcgrawhill.com/sites/0072437316/student_view0/chapter1
4/animations.html
• 1. mRNA: messenger RNA, a copy of
DNA from the nucleus.
• Reads DNA and copies it into RNA
T
A
DNA
A
U
C
G
RNA
• 2. rRNA : ribosomal RNA, found on the
ribosomes and functions in
attaching to mRNA to assemble the
correct order of amino acids.
Binds to mRNA
Binds to tRNA
• 3. tRNA : transfer RNA, located in
cytoplasm
• it picks up amino acids and like a factory
worker it puts the correct amino acid in
place to build a protein.
• Each tRNA has an anticodon on it that
corresponds to the mRNA codon read off
of the DNA.
A
U
Serine (amino acid)
tRNA
G
U
C
A mRNA
I. Transcription:
1. DNA unzips with the help of RNA
Polymerase
http://www.dnatube.com/video/3450/DNATranscription
http://w
2. mRNA reads the DNA, RNA Polymerase ww.dnat
ube.com
bonds the RNA nucleotides together.
/video/3
446/Bio
Rap3. mRNA breaks off and leaves the
DNAnucleus and travels to the ribosomes in theReplicati
on-andcytoplasm.
ProteinSynthesi
DNA strand
TAC GCT TAG TTA ACT
s-with-amRNA strand AUG CGA AUC AAU UGA Beat
II. Translation:
1. mRNA attaches to ribosome. The ribosome
reads 1 codon at a time. The process begins with a
start codon.
2. tRNA with an amino acid finds its anticodon
complement on mRNA’s codon.
mRNA : AUG UUU CCC CGA - codons
tRNA : UAC AAA GGG GCU - anticodons
3. Ribosomes continue to read the codons
and another tRNA attaches leaving another
amino acid.
4. Step 3 continues until the whole strand of
mRNA is read, when the stop codon is reached
the protein is completed.
http://highered.mcgrawhill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::5
35::/sites/dl/free/0072437316/120077/micro06.s
wf::Protein
Synthesis
http://www.biotopics.co.uk/genes/translation.html
Prokaryotic Transcription:
Operon – a region of DNA that contains a promoter,
operator, and structural genes.
1. Promoter – DNA segment that allows a gene to be
transcribed, RNA Polymerase binding site.
2. Operator – DNA segment that turns a gene “on” or “off”
*The lac operon was one of the earliest exps of gene
regulation in bacteria
Lactose absent
http://pages.cs
am.montclair.e
du/~smalley/L
acOperon.mo
v
Lactose present
http://wwwclass.unl.edu/biochem/gp2/m_biol
ogy/animation/gene/gene_a2.html
http://www.biologycorner.com/bio4/notes/gene-expression.php
– The lac operon is “off” when lactose is not
present.
– The lac operon is “on” when lactose is present.
Eukaryotic Transcription:
*Transcription is controlled by regulatory DNA sequences and
protein transcription factors.
– Most eukaryotes have a TATA box promoter.
– Enhancers and silencers speed up or slow down the rate
of transcription.
3 Steps
1. Addition of the cap
2. Addition of the tail
3. Removal of introns with the splicing together of exons
Exons - code for parts of the protein
Introns – nucleotides that occur between exons
http://nortonbooks.com/college/biology/ani
mations/ch13a05.htm
http://nortonbooks.com/college/biology/ani
mations/ch12a05.htm
Gene mutations: a change in the sequence of nucleotides within
a gene.
When do mutations occur?
- most often during DNA replication.
Different Types (pg 253 Fig 8.20)
1. Point Mutations- 1 nucleotide is changed to another, thus
coding for a different amino acid. Single base
pair substitution.
2. Frameshift mutations- add or delete a nucleotide to cause
the other bases to move up or down the
DNA molecule.
http://nortonbooks.com/college/biology/ani
mations/ch13a08.htm
(Change in chromosome structure)
Different Kinds
1. Deletion: when part of a chromosome is left out.
2. Insertion: part of a chromosome breaks off and inserts into
another causing a duplication in the other
chromosome.
3. Inversion: genes break off and are reinserted backwards
4. Translocation: genes break off and add to a different
chromosome.(pg 253)
Causes: mutations are random events. Most often though
environmental factors play a huge role in gene mutations
Read p254-255 and answer Apply Q on p254, and Summarize Q on p255
http://www.teachersdomain.org/asset/lsps0
7_vid_rnai/
*Many chromosome mutations result when chromosomes fail to
separate properly during meiosis.
Nondisjunction - occurs when homologous chromosomes or
sister chromatids fail to separate.
Causes:
Down syndrome, Turners syndrome, Klinefelters
syndrome, cancer, etc.
http://www.biology.iupui.edu/biocourses/N100/2k2human
csomaldisorders.html http://www.pbs.org/wgbh/nova/body/rnai.ht
ml NOVA video (RNAi)
copyright cmassengale
• DNA is made up of a long chain of
nucleotides.
• Each nucleotide has three parts.
– a phosphate group
– a deoxyribose sugar
– a nitrogen-containing base
phosphate group
nitrogen-containing
base
http://www.sumanasinc.com/webcontent/
animations/molecularbiology.html
deoxyribose (sugar)