DNA Structure Flashcards
Different between structure and function of eu and heterochromatin?
Eu - white, in bead on string form as can be actively being transcribed/expressing genes
Hetero - black, solenoids, unable to be expressing genes. ONLY IN EUKARYOTES
What is the DNA double helix formed of?
- Phosphate group
- Deoxyribose sugar
- Nitrogenous Base (GTAC)
What is the use of DNA packing?
It’s too large to fit in the nucleus otherwise
What is the breakdown of structure of chromatin?
Double helix wrapped around histones, form solenoids (hetero).
What is a solenoid?
Double helix DNA wrapped round histone proteins.
What is a nucleosome?
One ‘bead on the string’ ie DNA round a histone core
Do chromosomes express genes?
No
What is the definition of a gene?
The code for a protein in triplet code.
Where are genes located?
Genes have a specific chromosomal location
How many genes do humans have? What is the genome?
Around 25000, all cells have all genes, phenotype differs
Define and name bases, nucleosides and nucleotides for DNA and RNA
Bases - Adenine, Guanine, Cytosine, Thymine/Uracil
Nucleosides - Base + Sugar e.g. Deoxyadenosine/Adenosine
Nucleotides - Base + Sugar + Phosphate - deoxyadenosine monophosphate, diphosphate, triphosphate. (dAMP or AMP etc)
What is the difference between ribose and deoxyribose?
Loss of O on carbon 2 deoxyribose (bottom right corner)
How is a phosphate attached to a deoxyribonucleotide?
Phosphodiester bond on carbon 5
What is the difference in structure between purines and pyrimidines?
Pyrimidines have one aromatic (carbon nitrogen) ring, purines have 2.
Name the two purines and two pyrimidines
Purines - adenine guanine
Pyrimidines - cytosine, thymine
