DNA structure/function Flashcards
What does DNA stand for?
DNA stands for deoxyribonucleic acid
What does DNA code for?
DNA codes for the sequence of amino acids in the primary structure of proteins
What does the primary structure of a protein determine?
The primary structure determines the final 3D structure and function of a protein
Brief description of DNA: (two points)
DNA is a polymer with a double helix structure
What monomer makes up DNA?
Nucleotide
What is a nucleotide made up of?
A pentose sugar (deoxyribose), a phosphate group and a nitrogenous containing base (cytosine, guanine, adenine and thymine)
What can the nitrogenous bases be? (four options)
Guanine, Cytosine, Adenine and Thymine
What is a polymer of nucleotide?
A polynucleotide
How do nucleotides join together?
Nucleotides join together through condensation reactions. By forming a bond between the phosphate group and the pentose sugar (deoxyribose)
Explain how a bond is formed between nucleotides: (two points)
The bond is formed through multiple condensation reactions. The condensation reactions occur between the deoxyribose sugar and the phosphate group, which create a phosphodiester bond
What is a phosphodiester bond?
A phosphodiester bond is a strong covalent bond that helps ensure the genetic code is not broken down
What forms the genetic code?
The nitrogenous bases form the genetic code
What is the sugar phosphate backbone? What has a sugar phosphate backbone?
The polynucleotide has a sugar phosphate backbone. The sugar phosphate backbone has strong covalent bonds between the sugar and phosphate groups that hold the polymer together
How does the DNA polymer occur? What does the DNA polymer form in structure?
The DNA polymer occurs in pairs, which join together by hydrogen bonds between the bases. The DNA polymer forms a double helix structure
Where do the hydrogen bonds form between?
The hydrogen bonds form between complementary base pairs
What does each nitrogenous base pair with?
Adenine and thymine forms a hydrogen bond
Guanine and cytosine form a hydrogen bond
How many hydrogen bonds are formed between each nitrogenous base?
Adenine and thymine forms 2 hydrogen bonds
Whereas cytosine and guanine form three hydrogen bonds
Why are the complementary base pairs important?
The complementary base pairing is important to help maintain the order of the genetic code when DNA replicates
How does the structure relate to function?
- The complementary base pairing allows identical copies to be made
- DNA being a large molecule enables it to carry lots of information
- The hydrogen bonds are weak so when DNA replication occurs the bonds will be easily broken and the replication of DNA can easily be done
- The molecule is double stranded so when DNA replication occurs one strand can act as an template
- DNA has a stable structure due to the phosphodiester bonds which create a sugar-phosphate backbone, leading to the formation of a double helical structure. This structure means the strong covalent bonds are on the outside of the helix, leaving the weaker hydrogen bonds in the middle of the helix, protected.
