Biology Nucleic Acids Overview

Nucleic Acids

• Nucleic acids are linear polymers that store and pass genetic information
• Two main types: DNA and RNA
• Both DNA and RNA are made up of nucleotides
• Nucleotides consist of a phosphate group, a sugar (deoxyribose in DNA, ribose in RNA), and a nitrogenous base.

Nucleotide Structure

• Nitrogenous bases:
  • DNA: Adenine (A), Guanine (G), Cytosine (C), Thymine (T)
  • RNA: Adenine (A), Guanine (G), Cytosine (C), Uracil (U)
• Sugar:
  • DNA: Deoxyribose
  • RNA: Ribose
• Phosphate group: Phosphate group links sugars to form the backbone (phosphodiester linkage)

DNA Structure

• DNA is a double helix structure
• The double helix consists of two antiparallel polynucleotide strands wound around each other.
• The strands run in opposite directions (5' to 3' and 3' to 5')
• Bases pair via hydrogen bonds (A-T, C-G) - Complementary base pairing

RNA Structure

• RNA is single-stranded
• Various types of RNA exist with different functions
• RNA also uses complementary base-pairing (A-U, C-G)

DNA Packaging

• DNA is highly organized within cells
• DNA wraps around proteins called histones to form nucleosomes.
• Nucleosomes coil into a 30 nm fiber, further condensed into higher-order structures to form chromosomes.

Chargaff's Rule

• In a DNA molecule, the amount of adenine equals the amount of thymine, and the amount of cytosine equals the amount of guanine.

Central Dogma

• DNA holds the genetic instructions.
• The central dogma describes the flow of genetic information.
• DNA is replicated to preserve information
• Transcription converts DNA to RNA (mRNA)
• Translation converts RNA to protein

Types of RNA

• mRNA (messenger RNA): Carries genetic information from DNA to ribosomes for protein synthesis
• rRNA (ribosomal RNA): Forms the structure of ribosomes, where protein synthesis occurs
• tRNA (transfer RNA): Brings amino acids to the ribosomes during protein synthesis.
• Other types of RNA: snRNA, snoRNA, miRNA, siRNA, incRNA, etc.

Gene Structure

• A gene is a sequence of DNA that codes for a protein.
• Genes contain exons (coding regions) and introns (non-coding regions).
• The coding region includes regulatory elements (promoter, polyadenylation signal) that control the expression of the gene.

Transcription Process

• The process of copying a gene's DNA sequence into RNA
• Initiation: RNA polymerase binds to the promoter region of the gene
• Elongation: RNA polymerase moves along the DNA template and adds complementary RNA nucleotides to the growing mRNA molecule.
• Termination: RNA polymerase reaches a termination signal and stops transcribing.

Translation Process

• The process of creating a protein from an mRNA molecule.
• mRNA is read in codons (three base sequences). Each codon specifies a particular amino acid.
• tRNA molecules bring the corresponding amino acids to the ribosome.
• Amino acids are linked together by peptide bonds to form a polypeptide chain.
• The polypeptide chain folds into a functional protein.

Genetic Code

• The genetic code is a set of rules that determines how codons in mRNA are translated into amino acids in proteins.
• Most amino acids are specified by more than one codon (redundant code).
• Start and stop codons signal the beginning and end of protein synthesis.

This quiz covers the essential concepts of nucleic acids, focusing on their structures and functions. You will explore the differences between DNA and RNA, including their nucleotide components and structural configurations. Test your knowledge on how these vital molecules store and transmit genetic information.