Structure of Nucleic Acids

What are the main nucleic acids and what are they made up of?

DNA: Deoxyribonucleic acid

RNA: Ribonucleic acid

• These are polymers made up of nucleotides (monomers)

What do the monomers of DNA consist of?

Nucleotides composed of a deoxyribose sugar, a phosphate group, and a nitrogenous base (adenine, thymine, cytosine, guanine)

What is the chemical structure and role of the phosphate group?

• 1 central phosphorus atom bonded to 4 oxygen atoms

• Connects the 5' -carbon of one sugar to the 3' - carbon of the next sugar

How does the deoxyriboses’ chemical structure allow DNA to form?

• A 5 sided, 5-carbon ring

• Carbons numbered 1 to 5 going clockwise from the 1'-carbon connected to the nitrogenous base

• Deoxygenated because it lacks 1 oxygen atom at the 2'-carbon position compared to ribose sugar

What is the 5 prime end of the deoxyribose sugar?

• The end of a DNA strand where the 5'-carbon of the deoxyribose sugar is free

• The carbon only binds to the phosphate group without connecting to another sugar

What is the 3 prime end of the deoxyribose sugar?

• The end of the deoxyribose sugar that has a free hydroxyl group (-OH) at the 3'-carbon position

• Essential for DNA synthesis and pairing with the phosphate group of the next nucleotide

• Called the growing/tail end

What are some key differences between DNA and RNA?

Nitrogenous bases: RNA has Uracil, DNA has Thymine

Pentose sugar: Sugar of RNA is oxygenated (ribose), DNA is deoxygenated (deoxyribose)

Structure: RNA generally single strand, DNA double helix

What is the chemical structure and location of the nitrogenous bases?

• Attached to the 1'-carbon of the deoxyribose sugar

• Each contains: Nitrogen, carbon, hydrogen and oxygen

•  Come in two types: Purines and Pyrimidines

• Connected to each other via weak hydrogen bondds

What are purines and which bases are classified as these?

Purines: Adenine and Guanine

• Double-ringed

• Tip: Purines are pure, angles have halo rings that are pure

What are pyramidines and which bases are classified as these?

Pyrimidines: Cytosine, Thymine, Uracil

• Single ringed

• TIP: Pyramids are sharp and CUT (acronym for 3 base names)

How is the bond that connects the nitrogenous bases different to the bond that connects the sugar-phosphate backbone?

Sugar Phosphate: Covalent peptide bond

• Peptide bond between the phosphate group of one nucleotide and the ribose sugar of the next nucleotide

Nitrogenous base: Hydrogen bond

• Bases held together by weak hydrogen bonds

What are the complementary base pairs?

• Adenine pairs with Thymine (Uracil in RNA) via 2 hydrogen bonds

• Guanine pairs with Cytosine via 3 hydrogen bonds

• Purines always pair with pyramidines

How and why are there complementary base pairs?

Complementary base pairs are formed through specific hydrogen bonding between nitrogenous bases. This pairing ensures accurate replication and transcription of genetic information, with adenine pairing with thymine (or uracil), and guanine pairing with cytosine. FIX THIS IS AI