What is the basic function of DNA?
Key Terms
What 3 things does a nucleotide consist of?
Nitrogen-containing organic base Pentose sugar Phosphate group
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| Term | Definition |
|---|---|
What is the basic function of DNA? | Used to store genetic information (all instructions organism needs to grow and develop from fertilised egg to adult) |
What is the main function of RNA? | Transfer genetic information from DNA to ribosomes |
What do ribosomes (AKA body’s ‘protein factories’) do? | Read RNA to make polypeptides in process called translation |
What are ribosomes made from? | RNA and proteins |
What 3 things does a nucleotide consist of? | Nitrogen-containing organic base Pentose sugar Phosphate group |
What are monomers that make up DNA & RNA? | Nucleotides |
How are polynucleotides formed? | Nucleotides join via condensation reaction between phosphate group of one nucleotide and sugar of another This forms a phosphodiester bond |
What is a chain of sugar and phosphates called? | Sugar-phosphate backbone |
What is the pentose sugar in a DNA nucleotide? | Deoxyribose |
Each DNA nucleotide has same sugar & phosphate group but a different ___ | base |
Name the 4 possible bases in a DNA nucleotide | Adenine (A) Thymine (T) Cytosine (C) Guanine (G) |
What is the pentose sugar in a RNA nucleotide? | Ribose |
Name the 4 possible bases in a RNA nucleotide | Adenine (A) Uracil (U) Cytosine (C) Guanine (G) |
Describe how the structure of DNA is formed | 2 DNA polynucleotide strands join together by hydrogen bonding between complementary base pairs 2 hydrogen bonds form between A & T, and 3 hydrogen bonds form between C & G 2 antiparallel polynucleotide strands twist to form DNA double-helix |
What does adenine pair with? | Thymine (A - T) |
What does cytosine pair with? | guanine (C - G) |
There is always _____ amounts of A & T in DNA molecule and C & G | EQUAL |
Ratio of A & T to G & C varies from… | species to species |
Describe the structure of RNA | Made from single polynucleotide chain = much shorter than most DNA polynucleotides |
Name the 3 Types of RNA in every cell | tRNA rRNA mRNA |
What does rRNA do? | Type of RNA that makes up ribosomes |
Explain how the structure of DNA is related to its functions (6) | Double helix protects bases from corruption Large molecule so can store lots of genetic information Helix/coiled so compact Double stranded so replication can occur semi-conservatively (Weak) H-bonds for replication Many H-bonds so stable Complementary base pairing so accurate identical copies can be made Base sequence allows information to be stored |
Explain why the replication of DNA is described as semi-conservative (2) | Each strand copied / acts as a template DNA has one new strand & one original |
Describe stage 1 of semi-conservative replication | DNA helicase breaks H bonds between bases = backbone is unzipped = helix unwinds |
Describe stage 2 of semi-conservative replication | Each original single strand acts as template for new strand: Free nucleotides are attached to their complementary base on the backbone (original strand) |