U1.1 Structure of DNA Flashcards
What does DNA stand for?
Deoxyribonucleic acid
What do DNA nucleotides comprise of?
Deoxyribose sugar, phosphate and a base.
What are the complementary base pairings in DNA?
adenine-thymine, cytosine-guanine
Describe the structure of DNA (strands).
Double-stranded double helix with anti-parallel strands.
What type of bond holds the sugar-phosphate backbone of DNA together?
Strong covalent bonds.
What are the base pairings a result of?
Weak hydrogen bonds between complementary bases.
What is at the 3’ end of a strand?
Deoxyribose sugar.
What is at the 5’ end of a strand?
An inorganic phosphate.
What does the base sequence of DNA form?
The genetic code.
Describe DNA in prokaryotes.
A single circular chromosome and smaller circular plasmids.
What is a plasmid?
A circular piece of DNA.
Describe DNA in eukaryotes.
Linear chromosomes held in the nucleus.
Describe the structure of eukaryotic chromosomes.
Tightly coiled and associated with proteins called histones.
Give two examples of organelles with circular chromosomes.
Mitochondria and chloroplasts.
How do yeast cells differ from most eukaryotic cells?
They contain plasmids.
