2.3 Nucleotides and Nucleic Acids

What is a nucleotide?

A molecule made of a pentose sugar, phosphate group and nitrogenous base

What elements are in nucleic acids?

Carbon, hydrogen, oxygen, nitrogen, phosphorus

What is a nucleic acid?

A polymer made of nucleotide monomers

What is a polynucleotide?

A long chain of nucleotides joined together

What bond joins nucleotides?

Phosphodiester bond

What reaction forms phosphodiester bonds?

Condensation reaction

What reaction breaks phosphodiester bonds?

Hydrolysis

What are the two types of nucleic acid?

DNA and RNA

What is the structure of a DNA nucleotide?

Deoxyribose sugar, phosphate group, base (A, T, C, G)

What is the structure of an RNA nucleotide?

Ribose sugar, phosphate group, base (A, U, C, G)

What are the 5 nitrogenous bases?

Adenine, thymine, cytosine, guanine, uracil

What are purines?

Double ring bases (adenine and guanine)

What are pyrimidines?

Single ring bases (cytosine, thymine, uracil)

What is complementary base pairing?

Specific pairing of bases via hydrogen bonds

What are the base pairing rules?

A pairs with T (or U in RNA), C pairs with G

What is the structure of DNA?

Double helix of two antiparallel strands

What does antiparallel mean?

Strands run in opposite directions

What is the sugar-phosphate backbone?

Alternating sugar and phosphate forming the structure of DNA/RNA

What is a hydrogen bond?

Weak bond between complementary bases

Why does DNA have equal A=T and C=G?

Because of complementary base pairing

What is the role of DNA?

Stores genetic information

What is the role of RNA?

Transfers genetic information for protein synthesis

What is ATP?

A nucleotide derivative used as an energy source

What is the structure of ATP?

Adenine, ribose, three phosphate groups

How is energy released from ATP?

Hydrolysis of ATP to ADP + Pi releases energy

What is phosphorylation?

Addition of a phosphate group to a molecule

What are the properties of ATP?

Small, water soluble, releases energy in small amounts, easily regenerated

What is DNA replication?

Process of copying DNA before cell division

What is semi-conservative replication?

Each new DNA molecule contains one original and one new strand

What enzyme breaks hydrogen bonds in DNA replication?

DNA helicase

What enzyme joins nucleotides in DNA replication?

DNA polymerase

Outline DNA replication.

DNA unwinds → strands separate → complementary nucleotides pair → DNA polymerase joins them → two identical molecules form

Why is DNA replication important?

Ensures genetic information is passed to daughter cells

What is a gene?

A sequence of DNA that codes for a protein

What is the genetic code?

Triplets of bases (codons) that code for amino acids

What is a mutation?

A change in the DNA base sequence

Why is complementary base pairing important?

Allows accurate DNA replication

Why is DNA double-stranded?

Provides stability and allows replication