A1.2 Nucleic Acids Flashcards
Gene
A length of DNA that codes for a polypeptide, which forms a protein.
Where is DNA found
- The nucleus
-Chromosomes and in the nucleus of eukaryotes and the plastids of prokaryotes
-mitochondria - chloroplasts
Why are viruses not considered living organisms?
Because they require living host cells to replicate their DNA and synthesise their proteins.
DNA and RNA are polymers of ____
Nucleotides
What do nucleotides contain
- phosphate group
- nitrogen base
- sugar
What are the 5 nitrogenous bases?
Adenine, Thymine, Guanine, Cytosine, Uracil
What type of bonds join the parts of a nuclotide?
Covalent bonds
What forms the backbone of DNA
Sugar- phosphate bonds
Nucleotide sugar in DNA
Deoxyribose
Nucleotide sugar in RNA
Ribose
How are nucleotides of RNA joined?
condensation rxns
What shape is DNA
Double helix
Anti-parallel
The way DNA strands run. Parallel but in opposite directions.
How are bases in DNA held together?
Weak H bonds
How many H bonds are there between guanine and cytosine?
3
How many H bonds are there between adenine and thymine?
2
What are the three kinds of RNA?
- Messenger RNA (mRNA)
- Transfer RNA (tRNA)
- Ribosomal RNA (rRNA)
Why is the genetic code stored in DNA said to be universal?
The same DNA triplet codes for the same amino acids in every organism
What DNA bases are purines?
Adenine and guanine
What DNA bases are pyrimidines?
Thymine and cytosine
How do purines and pyrimidines bond?
Double ring purines always bond to single ring pyrimidines.
Nucleosome
DNA is wound around histones which are grouped into bead like structures of 8 molecules with other histones on the outside of DNA.
Linker DNA
The DNA that links the nucleosome “beads”
Chargaff’s experiment
Showed the same relative amounts of purines and pyrimidines in DNA. Showed that aproximately 1:1 ratios of adenine and thymine and cytosine and guanine exist in DNA.
