DNA Flashcards
Explain the major work of Griffith and the major conclusions
His experiment was the first that suggested that bacteria are capable of transferring genetic information. He concluded that there are chemical factors that pass of genetic information; a transformation molecule. He also concluded that killed bacteria won’t make you sick, must be alive
Define Transformation
The genetic alteration of a cell resulting from the direct uptake and incorporation of genetic material (originating from outside the cell)
Explain the work of Avery and the major conclusions
Avery read Griffiths publication and progressed it. He concluded that DNA is the transforming factor. He eliminated groups of molecules one at a time to conclude his theory.
ie. one sample = no proteins and one with no RNA (Transformation occurs), one sample = no DNA (no transformation).
Explain the Hershey Chase experiment and the conclusion
Concluded that genetic material is DNA, not protein.
Made the virus RNA radioactive, all bacterial it infected were radioactive. Made the outer layer of the virus radioactive, all bacteria effected were not radioactive.
Describe the Watson-Crick model of DNA
They proved that DNA is a double stranded helical molecule. Used Rosalind Franklins research to help prove their theory and created a 3D model of DNA out of cardboard and wire.
Describe the structure of DNA
- > Double Stranded Helix
- > consists of two sugar-phosphate backbones, which are held together by hydrogen bonds between pairs of nitrogenous bases
- > Made up of nucleotides
- > 2 categories of Nitrogenous bases (Purines: AG and Pyrimidines: TC)
- > A+TorU = 2 hbonds G+C= 3 bonds
Describe a DNA Nucleotide
A nucleotide consists of…
- > 1 nitrogenous trait
- > Phosphate groups
- > Deoxyribose (5 carbon sugar)
Explain the process of DNA Replication
- > DNA molecule must unwind
- > DNA must unzip (H-Bonds are broken by helicase)
- > Primase places the first few nucleotides on the strand and prepares it for DNA polymerase
- > DNA polymerase binds to the primed site and lays down complementary nucleotides
- > Ligase bonds the backbone fragments together on the lagging strand
- > Each new DNA molecule is half old, half new
Explain the function of DNA polymerase, helices, ligase and primase
Helicase - > Disrupts the H-Bonds between the strands
Primase - > Lays down the first several nucleotides to prepare the strand for DNA polymerase
DNA polymerase -> Attaches nucleotides to the strand following the rules of base- pairing. It then proofreads its work
Ligase - > Bonds the Okazaki fragments on the lagging strand together
Describe the difference between DNA and RNA
DNA - Double Helix - Deoxyribose - Thymine RNA - Single stranded helix - Ribose sugar - Uracil
Name and explain the role of the 3 RNA molecules in protein synthesis
mRNA - > (messenger) The product of transcription. They are the instruction for which amino acids are strung together to make proteins. The edited mRNA leaves the nucleus to find a ribosome.
tRNA - > (transfer) Made of two main parts, amino acids + anti codon. The anti codon is complementary to the codon of mRNA (mRNA goes in wheel)
rRNA - > (ribosomal) Makes up part of the structure of the ribosome
Describe Transcription
DNA in the nucleus is read and copied as RNA. It then leaves the nucleus to find a ribosome
Explain RNA editing
1) Transcription occurs in the nucleus and the mRNA breaks away from the DNA
2) The RNA gets chopped up into 2 types of pieces, introns and exons
3) The exons get glued back together and exit the nucleus, get expressed
4) The introns are recycled
Describe Translation
tRNA is read and makes a protein in the ribosome
Explain the types of gene mutations and their effect on the protein
Point Mutation: Any change in any one or more nucleotide
Frameshift Mutation: Causes a shift in the grouping of codons, caused by insertion or deletion
Substitution -> One nucleotide is replaced with another
Insertion - > An extra nucleotide is added
Deletion - > A nucleotide is removed
