Structure of DNA Flashcards
Basic Structure of DNA (out of 4):
- Double helix shape (two twisting strands)
- Each strand formed from single unites called nucleotides
- Has a sugar-phosphate backbone
- Deoxyribose
Nucleotides:
single units of nucleic acid that are formed by a phosphate attached to a sugar, which has a base attached to it
Bases in nucleotides serve what purpose?
to join the two twisting strands through hydrogen bonds
Complementary Base pairing in DNA:
Cytosine — Guanine
Thymine — Adenine
Each strand of DNA contains _____
millions of base pairs and is coiled to form chromosomes
What are strands of nucleotides and what are their purposes (out of 6):
- joined by covalent bonds
- the sequence of bases makes up the genetic code
- the bases are read in groups of three (triplets)
- triplets are used to send instructions in the cell
- strands run anti-parallel (in opposite directions)
Qualities of the sugar-phosphate backbone:
hydrophilic so is positioned on the outside
Qualities of the nitrogenous bases:
very reactive so are protected on the inside
Complementary Base pairing in RNA:
Cytosine — Guanine
Uracil — Adenine
Basic Structure of RNA (out of 2):
- Single stranded and often linear in shape
- Ribose
DNA supercoiling:
the over or underwinding of a DNA strand
Histone:
protein providing structural support to a chromosome
Nucleosome:
the basic structural unit of DNA packaging in eukaryotes
Process of DNA supercoiling:
Nucleosomes protect the DNA, allowing it to be packaged. This allows for it to be supercoiled which is formed by wrapping DNA around histone proteins
Prokaryotic DNA:
not organised by histones and is often referred to as ‘naked’
