Nucleic Acids 2.3 Flashcards
This question is about nucleic acids
Explain How Dna Replicates
7 MARKS
- semi-conservative (replication)
- (double) helix, untwists / uncoils / unwinds / unravels
- hydrogen bonds (between bases) break
- each strand acts as the template (for the formation of a new molecule)
- free (DNA) nucleotides (align with exposed bases)
- complementary base pairing / purine to pyrimidine
- hydrogen bonds (re)form
- sugar-phosphate backbone forms / adjacent nucleotides join
- DNA polymerase joins , backbone / strands
- each new molecule has 1 old and 1 new strand
Explain how the structure of DNA Allows for replication
5 MARKS
- double stranded
- each / both (strands) act as template
- hydrogen bonds , easily , break / form , between bases
- complementary (specified) base , pairing / AW
- purine (only able to) bind to pyrimidine
- (due to) different sizes of purines and pyrimidines
- hydrogen bonding different between A & T and C & G or 3 H bonds between C & G and 2 H bonds between A & T
Deoxyribose is a pentose sugar that is a component of the double-stranded DNA molecule
Describe the structural relationship between deoxyribose and the other components of the DNA molecule
- part of nucleotide
- bonded / joined / attached , to (named) base and phosphate
- phosphate (joined) to C5 (and C3) / base (joined) to C1
- (deoxyribose is part of) backbone (of DNA)
- idea of linking with (second) phosphate on adjacent nucleotide
- nucleotide is , monomer / repeating unit , of DNA / polynucleotide
Describe the process of transcription
- DNA / gene , copied / transcribed , into mRNA
- free / activated , (RNA) nucleotides / (RNA) nucleoside triphosphates
- (line up by) complementary base-pairing / described
- (to) one / template / reference / sense , (DNA) strand
- (catalysed by) RNA polymerase
Describe the process of translation
- (mRNA moves to) ribosomes
- tRNA (molecules) bind to mRNA
- anticodon(s) , match / pair with / bind to , codons
- specific / correct , amino acid attached to tRNA
- formation of peptide bond between amino acids
Describe how a nucleotide base sequence in a gene is used to synthesise a polypeptide (7)
Transcription + Translation Description
7 MARKS
Transcription
- DNA / gene , copied / transcribed , into mRNA
- free / activated , (RNA) nucleotides / (RNA) nucleoside triphosphates
- (line up by) complementary base-pairing / described
- (to) one / template / reference / sense , (DNA) strand
- (catalysed by) RNA polymerase
Translation
- (mRNA moves to) ribosomes
- tRNA (molecules) bind to mRNA
- anticodon(s) , match / pair with / bind to , codons
- specific / correct , amino acid attached to tRNA
- formation of peptide bond between amino acids
What does Helicase Do
unwinds the DNA by breaking the hydrogen bonds between complementary base pairs on the two strands of DNA.
What does DNA Polymerase
catalyses the synthesis of DNA molecules from free nucleotides
Why is DNA Replication called semi conservative
each DNA molecules has one parental and newly synthesized strand
What bases are purines
Adenine and Guanine
h
Identify Features of the genetic code
- Non-overlapping: Each triplet is only read once
- Degenerate : more than one triplet codes for the same amino acid
- Universal : Same Bases and Sequences used by all species
Describe How Dna can be purified by precipitation
- Cutting the cells to break up the plasma nuclear membranes
- Adding detergent to break up the plasma and nuclear membranes
- Adding Ethanol to precipitate the DNA
- Filtering the mixture to remove organelles
