Download CHAPTER 10: DNA,RNA & Protein Synthesis

yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts

Promoter (genetics) wikipedia, lookup

Agarose gel electrophoresis wikipedia, lookup

Community fingerprinting wikipedia, lookup

List of types of proteins wikipedia, lookup

RNA polymerase II holoenzyme wikipedia, lookup

Maurice Wilkins wikipedia, lookup

Transcriptional regulation wikipedia, lookup

Polyadenylation wikipedia, lookup

Eukaryotic transcription wikipedia, lookup

RNA silencing wikipedia, lookup

Messenger RNA wikipedia, lookup

Expanded genetic code wikipedia, lookup

Gel electrophoresis of nucleic acids wikipedia, lookup

Molecular cloning wikipedia, lookup

Silencer (genetics) wikipedia, lookup

Molecular evolution wikipedia, lookup

RNA-Seq wikipedia, lookup

Point mutation wikipedia, lookup

Vectors in gene therapy wikipedia, lookup

Non-coding DNA wikipedia, lookup

Cre-Lox recombination wikipedia, lookup

Biochemistry wikipedia, lookup

DNA supercoil wikipedia, lookup

Replisome wikipedia, lookup

Genetic code wikipedia, lookup

RNA wikipedia, lookup

Gene expression wikipedia, lookup

Artificial gene synthesis wikipedia, lookup

Non-coding RNA wikipedia, lookup

Epitranscriptome wikipedia, lookup

Deoxyribozyme wikipedia, lookup

Nucleic acid analogue wikipedia, lookup

DNA,RNA & Protein Synthesis
I. Discovery of DNA
• Scientist originally believed PROTEINS
would be the molecules which contained
hereditary information.
• Some scientists who did experiments that
proved DNA had genetic information:
– 1. Fredrick Griffith
– 2. Oswald Avery
– 3. Hershey & Chase
4. James Watson &
Francis Crick
• In 1953 DNA structure discovered
• Double Helix model.
– (2 chains of DNA)
– Showed how DNA could replicate.
• Relied on work of other scientists:
– Rosalind Franklin & Maurice Wilkins took
X-ray photos of DNA structure
– ( Franklin died 1958 before Watson & Crick
received Nobel Prize. 1962.)
II. DNA structure
A. Double Helix shape is
formed by base pairs
attached to a sugarphosphate backbone.
B. Parts of Nucleotides
1. 5 carbon sugar in DNA- deoxyribose
(in RNA= ribose)
2. phosphate group
3. nitrogenous bases ( there are 4 different
• Adenine
• Guanine
• Cytosine
• Thymine
(in RNA- no thymine- Uracil is the base)
C. How Chemical Bonds hold
DNA together
• Covalent bondsbetween sugar &
phosphates of 2
• Hydrogen bondsbetween complementary
nitrogenous bases –
D. Base Pairing Rules
• Adenine always bonds
with Thymine (AT)
• Guanine always bonds
with Cytosine (GC)
• Note: 3 hydrogen bonds: GC
– 2 Hydrogen bonds: AT
Must have 1 purine (a 2 ring shape) plus 1
pyriomidine (1 ring shape) in each pair or the
would not “fit” inside ladder of DNA
• 2. Purines (A, G) double C ring
• 3. Pyrimidines (T, C) single C ring
III. DNA Replication
A. Is the process by which DNA is copied in
a cell before a cell divides by mitosis,
meiosis or binary fission.
B. Steps in Replication
1. Helicase enzymes -
separate hydrogen bonds
in strands – create
replication fork
2. Attach- DNA polymerase
enzyme -adds nucleotides
3. Release –DNA
polymerase enzyme – now
have 2 identical DNA
C. Errors
• DNA replication is very accurate.
• Errors occur ~ 1 in 1 billion paired
• “Proofreading” enzyme checks for “spelling”
*If a mistake does occur- new DNA is different:
• Mutation- a change in the nucleotide
sequence of a DNA molecule.
• Caused by chemicals, radiation,UV rays.
• Mutations can be favorable
• - or harmful. (example- cancer)
IV Protein Synthesis
A. Flow of Information (DNA – RNA - Proteins)
Before protein can be synthesized, the instructions in
DNA must first be copied to another type of nucleic
acid called messenger RNA.
Then -a group of 3 nucleic acids codes for an amino
acid & it is built at the ribosomal RNA with help
from the transfer RNA
RNA differs from DNA in the
following ways:
• RNA is single stranded while DNA is
double stranded.
• RNA has a sugar called ribose while
DNA has a sugar called deoxyribose.
• RNA has the nitrogenous base uracil
while DNA has the base thymine.
B. 3 types RNA:
1. messenger RNA(mRNA)
2. transfer RNA (tRNA)
3. ribosomal RNA (rRNA)
1. Messenger RNA, or mRNA.
carries the code for building a protein from the
nucleus to the ribosomes in the cytoplasm. It acts
as a messenger.
2. Transfer RNA or tRNA.
picks up specific amino acids in the cytoplasm &
brings them into position on ribosome where
they are joined together in specific order to
make a specific protein.
3. Ribosomal RNA or rRNA
place for protein synthesis
C. Steps in Transcriptionmaking RNA
1. RNA polymerase (enzyme)–
binds to promoter area on
2. Nucleotides added & joined by
the enzyme (RNA polymerase)
3. Termination signal- stopRNA polymerase releases both
DNA & new RNA molecules
D. Proteins
• Review of protein structure
-recall that proteins are made of
amino acids joined together with
peptide bonds
-there are 20 different amino acids,
the order they are joined determines
the structure & function of the
-proteins can be very large,
complicated molecules
mRNA codons for specific amino acids
• Each 3 nucleotide sequence (letters) in
mRNA encodes for 1 specific amino acid,
or a “start” or “stop” signal.
• Each 3 nucleotide group is called a codon.
• The genetic code- means the rules that
relate how a particular sequence of
nitrogenous bases corresponds to a particular
amino acid.
E. Steps in Translation
Initiation- tRNA & mRNA join together.
(The codon is on the mRNA, the “anticodon” is on tRNA)
The tRNA has an amino acid attached to it)
2. Elongation- continued as ribosome moves the
distance of 1 codon on mRNA
3. Elongation is built with new tRNAs attaching each
amino acid as it reads the codons on the mRNA.
4. Termination- ribosome reaches “stop” codon on
the mRNA
5. Disassembly – each piece is free.
(see sequence page 208-209 in textbook)
• Replication- copying DNA from DNA
• Transcription- making RNA from DNA
• Translation- making proteins