1.4 - Nucleic acids Flashcards
What is DNA?
polymer that contains genetic information
Function of RNA
transfer genetic information from DNA to ribosomes
What are ribosomes formed from?
RNA and proteins
Name the 3 components of a DNA nucleotide
- deoxyribose sugar
- phosphate group
- nitrogenous base (A,T,C,G)
Name the 3 components of an RNA nucleotide
- ribose sugar
- phosphate group
- nitrogenous base (A,U,C,G)
Which bond does a condensation reaction between two nucleotides form?
phosphodiester bond
between deoxyribose and phosphate
Describe the structure and bonding of a DNA molecule
- double helix with 2 polynucleotide chains
- held together by H bonds
- between complementary base pairs
How long is an RNA molecule?
relatively short polynucleotide chain
Describe the semi-conservative model of DNA replication
- DNA helicase breaks H bonds between complementary bases on polynucleotide strands
- unwinds double helix as strands separate
- 1 strand used as a template
- attraction of new DNA nucleotides to exposed bases on template strands leading to complementary base pairing
- DNA polymerase joins adjacent nucleotides by phosphodiester bonds in a condensation reaction
- forms 2 identical new DNA strands
What does the semi-conservative theory of DNA replication ensure?
genetic continuity between generations of cells
Why is DNA a stable molecule?
- phosphodiester backbone protects nitrogenous bases inside double helix
- more H bonds between base pairs = more stable, so a higher proportion of C-G pairings makes DNA more stable
How many H bonds form between A-T and C-G?
A-T: 2
C-G: 3
Describe the structure of DNA
- polymer of nucleotides
- nucleotides made up of deoxyribose, phosphate and nitrogenous base
- phosphodiester bonds between nucleotides
- strands held together by H bonds
- base pairing between A+T, C+G (write full names)
