Unit 1 KA1 Flashcards
Nucleic acids
Class of chemicals including DNA and RNA
DNA
Complex molecule made of 2 polynucleotide strands. Contains genetic information in its sequence of bases (the genetic code).
Nucleotide
Building block of nucleic acids (DNA and RNA). Made of a 5C sugar, a phosphate and one of 4 bases - adenine, cytosine, guanine and thymine (DNA) or uracil (RNA).
Complementary base pairing
Matching bases join by hydrogen bonds to hold 2 strands of nucleotides together.
adenine - thymine/uracil
cytosine - guanine
Double helix
The double stranded DNA molecule twists to form this shape.
Antiparallel
One DNA strand is upside down compared to the other strand.
Sugar-phosphate backbone
The deoxyribose of one nucleotide joins to the phosphate of the next with a strong covalent bond creating the sides of the DNA ladder.
Deoxyribose
5 carbon sugar which forms part of the structure of a DNA nucleotide.
Genetic code
The sequence of bases in a gene, which determines the amino acid sequence of a protein.
Transforming principle
A chemical (now known to be DNA) can transfer from a dead to a live bacterium and transform it into a different strain.
Bacteriophage
A virus that attacks bacterial cells. Used to discover that DNA is the genetic material.
X-ray crystallography
A technique that allows molecules to be photographed.
When X-rays are fired at a molecule, a scatter pattern is created.
Used to work out the structure of DNA.
Prokaryote
Lack a true nucleus, eg. bacteria and archaea.
Have circular DNA free in the cytoplasm
Plasmid
A tiny DNA ring found in bacterial cells (and some fungal cells).
Eukaryote
DNA is contained in a true membrane-bound nucleus eg. animal, plant and fungal cells.
Histones
Linear DNA is wrapped around these proteins, to allow it to be organised and packaged into the nucleus.
Found in eukaryotes.
Covalent bond
A strong chemical bond.
Joins nucleotides together.
Hydrogen bond
A weak bond resulting from an attraction between hydrogen and other atoms.
Used to hold strands of nucleotides together (complementary base pairing).
3’ end
The end of the DNA strand that has deoxyribose.
5’ end
The end of the DNA strand that has phosphate.
