- Summary list for 2.6 structure of DNA and RNA
- Mindmaps
- Exam style question about DNA structure
- Model answer
- Model answer
- 2.6 DNA and RNA 1/1
Summary list for 2.6 structure of DNA and RNA
- DNA and RNA are polymers each made of nucleotides.
- A DNA nucleotide is made from phosphate, deoxyribose (pentose sugar), and nucleotide bases (T, A,G,C)
- RNA nucleotides are made from phosphate, ribose (pentose sugar) and nucleotide bases (U, A, G, C)
- Base pairing is "complementary"
- DNA is a double helix made of two strands of nucleotides linked by hydrogen bonding RNA is a single strand of nucleotides.
- Students should be able to draw simple diagrams of DNA and RNA nucleotides - using simple shapes (not chemical symbols). Two antiparallel strands of DNA showing base pairing. A 'ladder' structure is enough.
Details of purines / pyrimidines are not required at SL.
Mindmaps
This diagram summaries the main sections of topic 2.6.
Test if you can draw something like these concept maps from memory.
Exam style question about DNA structure
Understanding the structure of DNA and RNA is an important skill from this topic.
Answer the question below on a piece of paper, then check your answer with the model answer below.
Draw a simple diagram showing the structure of a short piece of RNA made of three nucleotides [4]
.
.
.
.
.
.
Click the + icon to see a model answer.
This question requires knowledge of the relationship between DNA structure and function.
The diagram shows the structure of DNA
a) Annotate the diagram to show a nucleotide (1 mark)
b) Describe what the dotted lines represent (1 mark)
.............................................. ............................................
.............................................. ............................................
Click the + icon to see a model answer.
This is a self marking quiz containing questions covering the topic outlined above.
Try the questions to check your understanding.
START QUIZ!
To which carbons of deoxyribose is the phosphate groups bonded in DNA?
The nucleotide base is bonded to carbon 1
Carbons 3 and 5 form the sugar -phosphate bond by binding to phosphate.
Which of the following are found in DNA but not in RNA
Thymine and deoxyribose are found only in DNA and not in RNA
Where do hydrogen bonds form in molecules of DNA?
Diagrams of DNA often show dotted lines between the nucleotide base pairs representing the hydrogen bonds that hold the DNA strands of the double helix together.
Which bases pair with T and G in DNA structure?
C always pairs with G and vice versa.
A always pairs with T, and vice versa.
In what ways is RNA the same as DNA?
RNA and DNA share the same phosphate, the bases A,C and G.
Both can form hydrogen bonds in the same way, but as RNA is single stranded the hydrogen bonding is different from DNA, depending on the type of RNA.
Which of the following is a correct drawing of an DNA nucleotide?
The deoxyribose connects the phosphate to the thymine correctly in diagram A
In C and D the phosphate connects to the base, which is incorrect.
What is the difference between a ribose and a deoxyribose sugar molecule?
Both ribose and deoxyribose are pentose sugars with 5 carbon atoms in each.
Deoxyribose has one oxygen less than ribose, making one fewer -OH groups. The -OH becomes -H
In biology polymers are quite common types of molecules. Which of the following molecules are polymers?
Polymer is the chemical name for a long molecule made from repeated subunits called monomers.
These include, polysaccharides, polypeptides, and polymers of nucleotides, DNA and RNA.
Drag and drop activities
Test your ability to construct biological explanations using the drag and drop questions below.
Test your construction of biological explanations using the drag and drop questions below.
The structure of DNA.
G-C uracil monomer nitrogenous base guanine covalent nucleotides hydrogen phosphate ribose pentose complimentary backbone
Nucleic acids are polymers of .
The nucleotide consists of a sugar (deoxyribose in DNA or in RNA), a group and a (adenine, , cytosine and thymine.
The phosphate and sugar join in sequence with bonds to form the .
The bases form a base sequence on the inside of the molecule, bonded in base pairs (A-T, ).
Examiner hint: An annotated diagrm can be used to answer a question on the structure of DNA.
Try the DNA word shoot revision arcade game below.
Can you reach the leader board?
How much of Structure of DNA and RNA 2.6 have you understood?
Twitter 
Facebook 
LinkedIn