2.4 Flashcards
Who proposed a model for the structure of DNA and when?
James Watson and Francis Crick in 1953
What does DNA contain?
The genetic code that dictates all the inherited characteristics of an organism
What is a gene?
a sequence of bases on a DNA molecule that codes for a sequence of amino acids in a polypeptide chain
What is a genome?
All the genes in an individual (or species)
What are the units that make up the polymer DNA?
(mono)nucleotides
What are the three molecules in a nucleotide?
deoxyribose, a phosphate group and an organic base containing nitrogen
what is the reaction between the three molecules in a nucleotide?
condensation reactions
What is the only part of the nucleotide that is variable?
the nitrogen containing base
what are the four different bases?
adenine, cytosine, guanine and thymine
what is the bond between nucleotides?
a phosphodiester bond
What is the structure of DNA called?
a double helix
what is considered the ‘backbone’ of the double helix?
sugars and phosphates
what holds the bases in place in DNA?
hydrogen bonds
How are the two nucleotide strands described and why?
antiparallel as they run in opposite directions
What is the structure bases A and G have?
a two ring structure
what is the structure bases C and T have?
one ring structure
What forms each rung of the DNA molecule?
the three rings from the bases
How many hydrogen bonds to A and T forms
two
how many hydrogen bonds do C and G form?
three
what is the first stage of protein synthesis?
transcription
What is the ‘copy’ of the required gene made from?
ribonucleic acid (RNA)
What are the structural differences for RNA compared to DNA?
- Rna is single stranded
- Rna nucleotides contain ribose
- Rna nucleotides replace thymine with uracil
what is the Rna made is the nucleus called?
messenger RNA (mRNA)
What does RNA polymerase do during transcription?
it attaches to the DNA and allows the DNA molecule to unwind by breaking the hydrogen bonds between bases
