Transcription
Translation
Chromosomes
- First step in protein synthesis
- Involves making DNA into RNA using base coding, except Adenine now pairs with Uracil
- RNA: single stranded, ribose sugar, can leave nucleus
- RNA Polymerase reads the strand 3' to 5'
- Introns- areas of RNA not expressed, Exons- areas of RNA expressed
- composed of DNA
- sister chromatids connected at the centromere
- segments of the chromosome code for certain proteins
- mRNA goes to cytoplasm where many amino acids exist
- Each 3 bases (codon) on mRNA strand code for a single amino acid using a chart
- When the start codon is found the tRNA (transfer) attaches to RNA strand. One end has an antiocodon (base pairing) and the other has an amino acid.
- The next tRNA then connects to the next 3 bases, knocking off the first tRNA but leaving behind the amino acid.
- This process continues forming a long chain of amino acids, a polypeptide protein chain, until a stop codon is read.
- This protein can be in many forms, ultimately giving a trait its' functionality.
Transcription begins on area of DNA that contains the specific gene. 3 regions:
1. Promoter- turns the gene on or off (start of the gene)
2. Coding- how to construct the protein
3. Termination sequence- signals end of gene
Homeobox
(Ultimately turns DNA into mRNA)
Genes responsible for the broader, but very important, parts of embryonic development
Homeotic genes are almost identical in every species, especially species sharing a common ancestor
Mutations on these genes can lead to drastic differences in the appearance and physiology of species
Gene
Each specific gene codes for a protein which controls traits such as eye color, height, hair color, etc.
A gene is a segment of DNA that specififies the sequence of amino acids in a polypeptide of a protein.
Protein Synthesis
Genetic Mutations
These can occur during replication and protein synthesis
Point Mutation: One base is paired incorrectly. ie. A with G
1. DNA template strand (3'-5') is transcribed into mRNA using base pairing. However, Adenine now pairs with Uracil, Thymine still pairs with Adenine.
2. It is transcribed into mRNA because DNA cannot leave the Nucleus, however mRNA can. The mRNA now goes to the cytoplasm.
3. Ribosomes, floating around the cytosplasm, use the mRNA to translate into amino acid sequences. Three amino acids, a codon, codes for one amino acid.
4. These amino acids form a polypetide chain, ultimating forming a protein.
Mutations can lead to the creation of a new species- evolution
Frameshift Mutation: a base is added or removed
Silent Mutation: a base is changed but has no resulting effect on the amino acid
Using a special wheel you can determine which nucleotide sequences code for which amino acids.
Ex. AUG codes for Methionine
The genetic information responsible for the development and functioning of all living organisms. Long term storage of information and carries genetic information for passing along traits.
Proper Name:
Deoxyribonucleic Acid
DNA
DNA Replication
By Samantha Twardoch
Structure
Discovered
By:
Discovered by:
Steps:
1. DNA Helicase unzips DNA; junction called replication fork.
2. DNA Polymerase, travelling from 3' to 5', adds the complimentary nucleotides.
3. DNA Polymerase adds complimentary nucleotides on other side of the ladder, moving 5' to 3'.
4. Leading strand follows helicase as it unwinds.
5. Lagging strand moves away from the helicase.
Chargaff
Watson and Crick
Franklin and Wilkins
Hershey/Chase
Frederick Griffith:
- Used X-ray diffraction to get picture of X shape leading to structure
- Discovered the phosphate was on the outside of the structure of DNA
- Discovered Double Helix Shape
- Showed that each DNA Strand was a template for the other
- Credited with discovering the structure of DNA
- Discovered base pairing
- Realized there were equal amounts of Adenine and Thymine, and Guanine and Cytosine
- Used radioactive sulfur and radioactive phosphorous to track it through offspring
- Realized DNA was the molecule for heredity, not protein
- He used mice, injected with bacteria, to track the presence of the disease
- He realized that the transforming agent in bacteria was DNA
Okazaki Fragments:
- Small fragments are created to keep the new strand continuous after the slight discontinuity when the replication fork is reached
Replication can cause genetic mutations.
This is prevented by:
- DNA Polymerase "proofreading"
- DNA Repair Enzymes
Structure of DNA
Example of Base Pairing:
ACCGAGTCA
base pairs to
TGGCTCAGT
Nucleotide Bases
Phosphate Group
5 Carbon Sugar
- Phosphate is attached to sugar
- The 5' end has a free phosphate
- Makes up the outside of the DNA Structure
- Four Bases: Adenine always pairs with Thymine, Guanine always pairs with Cytosine
- Bases held together by hydrogen bond; make up middle of DNA Structure
- Adenine and Guanine are purines (2 rings)
- Cytosine and Thyine are pyrimidines (1 ring)
- Sugar is attached to phosphate
- The 3' end has a free sugar
- Makes up the outside of the DNA Structure
- Anti-Parallel Arrangement
- Deoxyribose Sugar