2.3 Nucleic Acids Flashcards
What is the structure of a purine base?
2 carbon-nitrogen rings
What is the structure of a pyrimidine base?
1 carbon-nitrogen ring
How many hydrogen bonds form between Adenine and Thymine
2
How many hydrogen bonds form between Cytosine and Guanine
3
What is the difference between a DNA and RNA nucleotide?
DNA- Deoxyribose pentose sugar and A,T,C,G
RNA- Ribose pentose sugar and A,U,C,G (Uracil)
1 DNA molecule consists of _ anti-parallel polynucleotide strand(s).
2
What bond is formed/broken when polynucleotides are made or broken?
Phosphodiester
What gives DNA molecules stability?
The double helix created by hydrogen bonds and the sugar-phosphate backbone
What is the structure of ATP and ADP?
Ribose pentose sugar, nitrogenous base adenine and 2/3 phosphate groups
Why is it important that the DNA molecule is stable?
To protect the coded genetic information and base sequence
What are the complementary base pairs?
A-T and C-G
How is DNA organised in Eukaryotes?
Each DNA molecule is wrapped around a histone protein into a chromosome.
A loop of DNA inside mitochondria and chloroplasts
How is DNA organised in Prokaryotes
In a loop of ‘naked’ DNA
How can you purify and extract DNA?
Precipitation
What is precipitation?
Macerate the tissue, add a strong detergent then add ethanol so the DNA precipitates out of solution
What does DNA polymerase do?
An enzyme that catalyses the addition of new nucleotide bases, in the 5’ to 3’ direction to the single unzipped DNA strand
What does DNA helicase do?
An enzyme that catalyses breaking the hydrogen bonds between DNA polynucleotide strands
What is semi-conservative replication?
How DNA replicates, making 2 new molecules, each containing 1 old strand and 1 new strand- 1 old strand is conserved in each molecule
What is a genome?
All the DNA within a cell
What is the 1st thing a DNA molecule must do before it can replicate?
Unwind the double helix, catalysed by DNA gyrase and unzip, catalysed by DNA helicase
How is the leading strand synthesised?
Continuously
How is the lagging strand synthesised?
In Okazaki fragments discontinuously, that are later joined by DNA ligase
What are different versions of the same gene called?
Alleles
What is a gene?
A section of DNA that codes for a particular protein