dna & protein synthesis
DESCRIPTION
DNA & Protein Synthesis. The student will investigate and understand common mechanisms of inheritance and protein synthesis. Key concepts include: f) the structure, function, and replication of nucleic acids (DNA and RNA); and g) events involved in the construction of proteins. - PowerPoint PPT PresentationTRANSCRIPT
DNA & Protein Synthesis
• The student will investigate and understand common mechanisms of inheritance and protein synthesis.
• Key concepts include:– f) the structure, function, and replication of
nucleic acids (DNA and RNA); and– g) events involved in the construction of
proteins.
• The student will investigate and understand common mechanisms of inheritance and protein synthesis.
• Key concepts include:– h) use, limitations, and misuse of genetic
information; and– i) exploration of the impact of DNA
technologies.
History
• Before the 1940’s scientists didn’t know what material caused inheritance.
• They suspected it was either DNA or proteins.
History
• A series of experiments proved that DNA was the genetic material responsible for inheritance.
History
• In 1952, Alfred Hershey and Martha Chase did an experiment using a virus that infects E. coli bacteria.
• The experiment proved that DNA and not protein is the factor that influences inheritance.
History
• Erwin Chargaff discovered the base pairing rules and ratios for different species.
• Adenine pairs with Thymine
• Cytosine pairs with Guanine.
History• Rosalind Franklin & Maurice Wilkins had
taken the 1st pictures of DNA using X-ray crystallization
This proved that DNA had a helical shape.
History• The Nobel Prize in Medicine 1962
Francis Harry Compton Crick
James Dewey Watson
Maurice Hugh Frederick Wilkins
Rosalind Franklin(Died of cancer 1958)
Wilkins has become a historical footnote and
Watson & Crick are remembered as the
Fathers of DNA
Watson Crick
DNADNA
OO=P-O O
PhosphatePhosphate GroupGroup
N
Nitrogenous baseNitrogenous base (A, T(A, T,, G, C)G, C)CH2
O
C1C4
C3 C2
5
SugarSugar(deoxyribose)(deoxyribose)
Nitrogen Bases
• 2 types of Nitrogen Bases– Purines
• Double ring–G & A
– Pyrimidines• Single ring
–C & U & T
PGA
CUT PY
DNA - double helixDNA - double helix
P
P
P
O
O
O
1
23
4
5
5
3
3
5
P
P
PO
O
O
1
2 3
4
5
5
3
5
3
G C
T A
T A
DNA
• The genetic code is a sequence of DNA nucleotides in the nucleus of cells.
DNA• DNA is a double-
stranded molecule.
• The strands are connected by complementary nucleotide pairs (A-T & C-G) like rungs on a ladder.
• The ladder twists to form a double helix.
DNA
• During S stage in interphase, DNA replicates itself.
• DNA replication is a semi-conservative process.
DNA• Semi-conservative
means that you conserve part of the original structure in the new one.
• You end up with 2 identical strands of DNA.
DNA
• Gene - a segment of DNA that codes for a protein, which in turn codes for a trait (skin tone, eye color, etc.)
• A gene is a stretch of DNA.
DNA
• A mistake in DNA replication is called a mutation.
• Many enzymes are involved in finding and repairing mistakes.
Mutations
• What causes mutations?– Can occur spontaneously– Can be caused by a mutagen
• Mutagen: An agent, such as a chemical, ultraviolet light, or a radioactive element, that can induce or increase the frequency of mutation in an organism.
Mutations
• Some mutations can:
• Have little to no effect
• Be beneficial (produce organisms that are
better suited to their environments)
• Be deleterious (harmful)
Mutations• Types of mutations
– Point Mutations or Substitutions: causes the replacement of a single base nucleotide with another nucleotide
• Missense- code for a different amino acid
• Nonsense- code for a stop, which can shorten the protein
• Silent- code for the same amino acid (AA)
Mutations
• Example: Sickle Cell Anemia
Mutations• Types of mutations
– Frame Shift Mutations: the number of nucleotides inserted or deleted is not a multiple of three, so that every codon beyond the point of insertion or deletion is read incorrectly during translation.
• Ex.: Crohn’s disease
Insertion Deletion
Mutations• Types of mutations
– Chromosomal Inversions: an entire section of DNA is reversed.
– Ex.: hemophilia,
a bleeding disorder
DNA Repair
• A complex system of enzymes, active in the G2 stage of interphase, serves as a back up to repair damaged DNA before it is dispersed into new cells during mitosis.
RNARNA
OO=P-O O
PhosphatePhosphate GroupGroup
N
Nitrogenous baseNitrogenous base (A, (A, UU ,, G, C )G, C )CH2
O
C1C4
C3 C2
5
SugarSugar (ribose)(ribose)
RNA
• Function: obtain information from DNA & synthesizes proteins
3 differences from DNA
1. Single strand instead of double strand
2. Ribose instead of deoxyribose
3. Uracil instead of thymine
3 types of RNA
1. Messenger RNA (mRNA)- copies information from DNA for protein synthesis
Codon- 3 base pairs that
code for a single amino
acid. codon
3 types of RNA
2. Transfer RNA (tRNA)- collects amino acids for protein synthesis
Anticodon-a sequence of 3 bases that are complementary base pairs to a codon in the mRNA
3 types of RNA
3. Ribosomal RNA (rRNA)- combines with proteins to form ribosomes
Amino Acids
• Amino acids- the building blocks of protein
• At least one kind of tRNA is present for each of the 20 amino acids used in protein synthesis.
Transcription - mRNA is made from DNA & goes to the ribosomeTranslation - Proteins are made from the message on the mRNA
Transcription
• In order for cells to make proteins, the DNA code must be transcribed (copied) to mRNA.
• The mRNA carries the code from the nucleus to the ribosomes.
Translation
• At the ribosome, amino acids (AA) are linked together to form specific proteins.
• The amino acid sequence is directed by the mRNA molecule.
ribosome
Amino acids
Make A Protein
• DNA sequence
ATG AAA AAC AAG GTA TAG
• mRNA sequence
UAC UUU UUG UUC CAU AUC
Make mRNA
• mRNA sequence
UAC UUU UUG UUC CAU AUC
• tRNA sequenceAUG AAA AAC AAG GUA UAG
Make mRNA
• mRNA sequence
UAC UUU UUG UUC CAU AUC
• Amino Acid sequence(protein)
Tyr Phe Cys Phe His Ile
Human Genome Project
• The Human Genome Project is a
collaborative effort of scientists around the
world to map the entire gene sequence of
organisms.
• This information will be useful in detection,
prevention, and treatment of many genetic
diseases.
DNA Technologies
• DNA technologies allow scientists to identify, study, and modify genes.
• Forensic identification is an example of the application of DNA technology.
Gene Therapy• Gene therapy is a technique for correcting
defective genes responsible for disease development.
• Possible cures for:– diabetes– cardiovascular disease– cystic fibrosis– Alzheimer's– Parkinson’s– and many other diseases is possible.
Genetic Engineering
• The human manipulation of the genetic
material of a cell.
• Recombinant DNA- Genetically
engineered DNA prepared by splicing
genes from one species into the cells of
a different species. Such DNA becomes
part of the host's genetic makeup and is
replicated.
Genetic Engineering • Genetic engineering techniques are used in
a variety of industries, in agriculture, in
basic research, and in medicine.
This genetically engineered cow resists infections of the udders and can help to increase dairy production.
Genetic Engineering • There is great potential for the development
of useful products through genetic
engineering• EX., human growth hormone, insulin, and pest-
and disease-resistant fruits and vegetables
Seedless watermelons are genetically engineered
Genetic Engineering • We can now grow new body parts and soon
donating blood will be a thing of the past,
but will we go too far?
Photo of a mouse growing a "human ear"