RNA and DNA Flashcards
what makes up an RNA nucleotide?
- ribose sugar
- phosphate
- organic base (A,U,C or G)
what makes up an DNA nucleotide?
- deoxyribose sugar
- phosphate
- organic base (A,T,C or G)
Give 4 differences between RNA and DNA
- DNA is longer, RNA is shorter
- DNA is double-stranded, RNA is single-stranded
- DNA contains deoxyribose, RNA contains ribose
- (some) DNA contains Thymine as a base, RNA contains Uracil
- C.B.P is present in DNA, it is not present in RNA
What is the role of DNA?
base sequence of genes codes for functional RNA and polypeptides
What is mRNA?
a single-stranded polynucleotide with a complementary base sequence to 1 gene from DNA (no introns)
What is rRNA?
a component that makes up ribosomes
What is the role of tRNA?
transfer complementary amino acid to the site of protein synthesis
how do polynucleotides form?
condensation reactions between nucleotides, forming phosphodiester bonds (sugar-phosphate backbone)
How many bonds form between A and T?
2 hydrogen bonds
How many bonds form between C and G?
3 hydrogen bonds
How is DNAs structure related to its function?
- many H bonds & sugar-phosphate backbone gives stability
- helix is compact, so lots stored in small space
- double-stranded for semi-conservative replication
- H bonds are weak (on individual scale) so can be broken for replication
- complementary base pairing
How does DNA replicate?
Semi-conservative replication
What is meant by semi-conservative replication?
one of the ‘old’ DNA strands and one new DNA strand make up the new DNA molecule
How is the structure of mRNA related to its function?
- breaks down quickly; so no excess polypeptide forms
- complementary codons so specific amino acids are coded for
- single stranded so ribosome can move along easily
Outline the process of semi-conservative DNA replication
1) DNA helicase breaks H bonds
2) strands acts as template molecules
3) free nucleotides line up with exposed bases in complementary base pairing
4) DNA polymerase catalyses the reaction forming phosphodiester bonds between adjacent nucleotides on new strand
5) H bonds reform