Lecture Notes: Genetics (Chapter 8)

Overview

Genetics: Science of inheritance or heredity
- How traits are transmitted from parents to offspring
- Expression of traits
- Structures of genetic material (DNA, RNA) and their functions
- Genetic material changes (e.g., mutations)

Genome: All genetic information of an organism
- Eukaryotes: Includes nucleus, mitochondria, and chloroplasts (if present)
- Prokaryotes: Includes nucleoid and plasmids
Chromosome: Structures made of DNA
- Prokaryotes: One large circular chromosome
- Eukaryotes: 5 to 200 linear chromosomes
Gene: Segment of DNA that codes for a protein
Genotype vs. Phenotype:
- Genotype: Genetic makeup
- Phenotype: Physical expression of traits (e.g., hair color)

Nucleotides: Building blocks of nucleic acids (DNA and RNA)
- Components: Sugar (deoxyribose in DNA, ribose in RNA), phosphate group, nitrogenous base
- Bonds: Covalent bonds (strong) between phosphate and sugar groups; Hydrogen bonds (weak) between nitrogenous bases
Nucleotide Pairing: Complementary Base Pairing
- DNA: Adenine (A) - Thymine (T), Guanine (G) - Cytosine (C)
- RNA: Adenine (A) - Uracil (U), Guanine (G) - Cytosine (C)
- Purines (A, G) vs. Pyrimidines (C, T, U)

Semi-Conservative Model: New DNA contains one old and one new strand
Important Enzymes: Roles and Functions
- Helicase: Unzips DNA
- DNA Polymerase III: Adds nucleotides, proofreading
- DNA Polymerase I: Removes primers, fixes mismatches
- Ligase: Joins Okazaki fragments on lagging strand
Direction: 5' to 3' synthesis direction, anti-parallel strands
- Leading Strand: Synthesized continuously
- Lagging Strand: Synthesized discontinuously in Okazaki fragments

DNA Transcription: DNA to RNA
RNA Translation: RNA to proteins
Key Players in Transcription: Roles and Functions
- RNA Polymerase: Builds RNA from DNA template
- Promoter Site: Binding site for RNA polymerase
- Terminator Site: End point for transcription
Key Players in Translation: Roles and Functions
- mRNA: Template for protein synthesis
- tRNA: Carries amino acids
- Ribosomes: Sites of protein synthesis

mRNA (Messenger RNA): Product of transcription, blueprints for proteins
tRNA (Transfer RNA): Carries amino acids to ribosome
rRNA (Ribosomal RNA): Component of ribosomes
Regulatory RNAs, Primer RNAs, Ribozymes: Additional RNA types with various functions

Prokaryotes: Transcription and translation occur simultaneously in cytoplasm
Eukaryotes: Transcription in nucleus, translation in cytoplasm

Mutation: Change in genetic information leading to altered protein
- Mutagens: Chemicals or radiation causing mutations
- Types of Mutations:
  - Missense: One amino acid change
  - Frameshift: Insertions/deletions shift reading frame
  - Nonsense: Changes codon to stop codon
Spontaneous Mutation Rate: Approx. 1 in 1 billion genes
Mutations: Role in Evolution: Beneficial mutations can lead to species adaptation

Methods:
- Conjugation: Plasmid transfer via pilus
- Transformation: Uptake of environmental DNA
- Transduction: Transfer via bacteriophage
- Transposons: Jumping genes, move within/between genomes