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Bio - DNA and RNA
Transcript of Bio - DNA and RNA
"the blueprint of life"
Contains the code (instructions) for building an organism and making it function.
Makes up the chromosomes in the nucleus of eukaryotic cells
Shape is a double-helix (like a twisted ladder)
Sides of the ladder made of alternating sugars (deoxyribose) and phosphates.
Rungs of the ladder made of nitrogen bases.
Nucleotides - units that make up DNA (a sugar + phosphate +nitrogen base)
Adenine, Thymine, Guanine, Cytosine or A, T, G, C
Adenine (A) pairs to Thymine (T)
Guanine (G) pairs to Cytosine(C)
the process of making a copy of DNA
Occurs during the synthesis (S) phase of the cell cycle.
Process of DNA Replication
1. The double helix is "unzipped" by DNA Helicases which break hydrogen bonds
2. DNA polymerase adds the complimentary nucleotides to the exposed bases.
Two completely identical strands of DNA
Checking for Errors
DNA polymerase "proofreads" as it moves along.
only get about one error per 1 billion nucleotides.
Transformation: process in which one strain of bacteria can be changed by genes from another strain
Transforming factor might be a gene
When they destroyed DNA (with enzymes), transformation did not occur
DNA was the transforming factor
Hershey - Chase
Genetic material of the bacteriophage was DNA (not protein)
Discovered DNA structure was a helix shape and might have two strands
Watson and Crick
First to model DNA as a double helix
the amount of guanine was almost equal to the amount of cytosine
the amount of adenine was almost equal to the amount of thymine
Hold the nitrogen bases together
A new nucleotide can only be added if the previous nucleotide was properly matched.
Structure of DNA
RNA and Protein Synthesis
What is RNA (Ribonucleic acid)?
A nucleic acid (just like DNA)
Made of nucleotides (just like DNA)
How is RNA different from DNA?
Has the sugar ribose instead of deoxyribose
Has the base uracil (U) instead of thymine (T)
Information from the DNA is copied onto an mRNA strand
How are proteins made?
The process of using mRNA as a template to arrange amino acids into proteins.
3 Types of RNA
messenger RNA (mRNA)
ribosomal RNA (rRNA)
transfer RNA (tRNA)
Uses RNA polymerase to seperate the DNA strands
One strand of DNA used as a template
Uses the same base pair rules as DNA replication, except adenine pairs with uracil instead of thymine
A = U and G = C
RNA polymerase binds to the promoter (a specific sequence of DNA that is a “start” signal for transcription)
The Genetic Code
three-nucleotide “words” found on the mRNA strand that code for a specific amino acid
Step 1: The mRNA leaves the nucleus
Step 2: mRNA attaches to a ribosome (made of rRNA)
Step 3: a tRNA carrying methionine will join at the "start" codon of mRNA (codon AUG)
Step 5: Peptide bonds are formed between the amino acids, linking them together
Step 6: After the amino acid is bonded, the tRNA is released
Step 7: Process continues until a "stop" codon is reached
Step 4: Each tRNA carries one specific amino acid and has an anticodon that matches up to an mRNA codon.
A change in the genetic material
Types of Mutations
a single nucleotide is changed
Ex: mutation that causes sickle-cell anemia.
one adenine is replaced by one thymine in DNA
DNA: CTC CAC
mRNA: GAG GUG
amino acid: Glutamic Acid Valine
changes that shift the "reading frame" of the genetic message by inserting or deleting a nucelotide
What causes mutations?
Damage from radiation, certain chemicals
Mistakes when DNA is copied
THE FAT CAT ATE THE RAT
HEF ATC ATA TET HER AT
Point Mutated Sequence
One base is exchanged for another
Extra base pairs are added to the sequence
Sections of DNA are lost
2 hydrogen bonds
3 hydrogen bonds