Nucleic Acids Flashcards
What elements are in nuclei acids?
CHONP Carbon Hydrogen Oxygen Nitrogen Phosphurus
What is the structure of DNA?
- Pentose sugar
- Phosphate group
- Nitrougenous base (T,A,G,C)
What is DNA built up of ?
Made up of basic blocks called nucleotides
What are the 4 nucleotides?
A, T, C, G
What are 3 differences between RNA and DNA?
- The sugar (ribose) compared to dna (deoxyribose)
- Uracil instead of thymine
- RNA is usually single stranded
Describe the semi-conservative replication of DNA
- An enzyme, DNA helicase, causes the two strands of the DNA to separate.
- DNA helicase, completes the separation of the strand.
- Meanwhile, free nucleotides that have been attracted to their complimentary bases.
- Once the activated nucleotides are lined up, they are joined together by DNA polymerase.
- The remaining unpaired bases continue to attract their complimentary nucleotide.
- All the nucleotides are joined to form a complete polynucleotide chain using DNA polymerase.
- Two identical molecules - one original strand and one newly formed molecule - semi conservative replication.
What happens if the sequence is copied incorrectly?
A mutation
Describe transcription
- mRNA made in the nucleus
- Hydrogen bonds between bases break and DNA uncoils
- A complimentary strand is made by copying the DNA strand, using it as a template.
- mRNA then transports the complimentary strand to the ribosome through a nuclear pore.
Describe Translation
- During translation amino acids form together to form a polypeptide chain.
- mRNA attaches to a ribosome and tranfer RNA (tRNA) collects amino acids from the cytoplasm
- tRNA attaches to mRNA by complimentary base pairing
- Amino acids attached to tRNA molecule join by a peptide bond and the tRNA then dettaches from the amino acids.
- This process is repeated thus leading to the formation of a polypoptide chain, until a stop codon is reached on mRNA and the process of protein synthesis
What is the role of rRNA?
Important in maintaining structural stability of the proteinsynthesis sequence and plays a biochemical role in catalysing the reaction.
What is the nature of genetic code?
Triplet code/non-overlapping
Degenrative
Universal
What does it mean that genetic code is triplet?
- The code in the base sequences is a simple triplet code
- It is a sequence called a codon
- Each codon codes for an amino acid
What does it mean that genetic code is degenerative?
There are more potential codons that amino acids
(64 potential and 20 amino acids)
- this means some amino acids can be coded by more than one codon.
What does it mean the genetic code is universal?
All organisms use the same code
Describe DNA extraction
- Grind sample in pestle and motar - breaks down cell walls
- Mix sample with detergent - breaks down cell memebrane
- Add salt - breaks hydrogen bonds between water & DNA
- Add protease enzyme - break down proteins
- Add ethanol - cause DNA to precipitate out
DNA seen as white strands forming between sample and layer of alcohol
