Biology · MU Pleven

3. Nucleic acids – structure and function of DNA and RNA.

Covers the two kinds of nucleic acid, DNA and RNA, starting from the nucleotide monomer and how nucleotides link through phosphodiester bonds into a sequence. It then describes the double helix with its complementary base pairs, the storage of DNA in chromatin and nucleosomes, and the functions of DNA. The note closes with RNA structure, its functions such as catalysis and regulation, and the roles of mRNA, rRNA and tRNA.

Inside: 10 sections · 5 labelled pictures · 20 flashcards · 5 min

Topic 3 of 63 in the MU Pleven syllabus for Biology (Medicine, Year 1). The free AceMed note covers it in 10 sections, about 673 words (5 min of reading), with 20 flashcards.

In this note

  1. Nucleic acids – structure and function of DNA and RNA.
  2. Two kinds: DNA and RNA
  3. Nucleotides function:
  4. Nucleosides:
  5. Secondary:
  6. DNA / Different secondary structures:
  7. Functions of DNA:
  8. RNA Structure:
  9. RNA functions:
  10. Types of RNA:

Two kinds: DNA and RNA

-DNA- double stranded, can self-replicate, makes up genes which codes for proteins and is passed from one generation to another

-RNA- single stranded, functions in actual synthesis of proteins coded for by DNA and is made from the DNA template molecule.

  • Both DNA and RNA are composed of nucleotide monomers, Nucleotide (5 carbon sugar), phosphate group and a nitrogenous base.
  • Phosphate of one nucleotide forms strong covalent bond with the 3’ carbon of the sugar of the other nucleotide
  • The function of nucleotides is to transfer chemical energy from one molecule to another (they are the monomers of nucleic acids)

Nucleotides function:

  • Monomers for Nucleic Acids; Transfer chemical energy from one molecule to another (e.g. ATP).
  • Building a polymer: Phosphate group of one nucleotide forms strong covalent bond with the 3 carbon of the sugar of the other nucleotide.

Nucleosides:

Consists of a nitrogen base linked by a glycosidic bond to C1’ of a ribose or deoxyribose . named by changing the nitrogen base ending to -osine for purines and –idine for pyrimidines . A nucleotide is a nucleoside that forms a phosphate ester with the C5’ OH group of ribose or deoxyribose Nucleotides are named using the name of the nucleoside followed by 5’-monophosphate

Phosphodiester bond DNA Structure (primary):

The primary structure of a nucleic acid is the nucleotide sequence, they are joined together by phosphodiester bonds.

  • The 3’OH group in one nucleotide forms an ester to the phosphate group on the 5’ carbon of the sugar of the next nucleotide.
  • A nucleic acid polymer has a free 5’ phosphate group at one end and a free 3’OH group at the other end. The sequence is read from the free 5’ using the letter of the bases i.e. 5’-A-C-G-T-3’7

Continue reading free

The whole note, all 10 sections, is free with an AceMed account, with its 20 flashcards. Premium adds flashcard recall, highlights and Ask AI.

Start freeAlready a member? Open the note