Biology Lecture: Evolution and Genetics

Introduction

• Third video in a series for biology exam prep (North Carolina EOC)
• Focus on evolution and genetics, constitutes almost half of the exam
• Encouragement to use linked resources and practice problems

Topics Covered

• DNA structure and function
• Protein synthesis
• Mutations
• Meiosis and genetic variation
• Patterns of inheritance
• Environmental influence on genes
• Biotechnology and genetic engineering
• Bioethics
• Evidence for evolution
• Natural selection
• Classification systems, dichotomous keys, and cladograms

DNA Structure and Function

• DNA: Deoxyribonucleic acid, composed of nucleotides (phosphate, sugar, base)
  • Bases: Adenine (A), Thymine (T), Guanine (G), Cytosine (C)
• Structure: Double helix, sugar-phosphate backbone, hydrogen-bonded bases
• Base Pairing: A pairs with T, G pairs with C
• DNA replication occurs in the S phase to ensure each daughter cell has a complete set

Protein Synthesis

• Process: DNA → mRNA → Protein
• Transcription: DNA to RNA
• Translation: RNA to protein
• Proteins perform various functions: hormones, enzymes, structural roles, etc.
• Differences between DNA (double-stranded, deoxyribose sugar, thymine) and RNA (single-stranded, ribose sugar, uracil)

Mutations

• Errors in replication, transcription, translation, or external sources (mutagens)
• Types: silent mutations, beneficial mutations, deleterious mutations
• Mutagens include x-rays, chemicals
• Can result in genetic disorders or changes in traits

Meiosis and Genetic Variation

• Key for sexual reproduction, producing haploid cells
• Sources of Variation:
  • Independent assortment
  • Crossing over during prophase I
  • Random fertilization
• Differences from mitosis: two divisions, produces gametes, involves crossing over

Patterns of Inheritance

• Types:
  • Complete dominance
  • Codominance
  • Incomplete dominance
  • Sex-linked traits
  • Multiple alleles (e.g., blood types)

Environmental Influence on Genes

• Genes exhibit different traits based on environmental exposure
• Example: Identical twins with different heights/weights due to environmental differences

Biotechnology and Genetic Engineering

• Techniques:
  • Gel electrophoresis (DNA fingerprinting)
  • Transgenic organisms
  • Human Genome Project
• Applications in agriculture, pharmaceuticals, environmental management

Evidence for Evolution

• Sources:
  • Biochemical (proteins, DNA)
  • Embryonic development
  • Fossil evidence
  • Anatomical evidence

Natural Selection

• Organisms better adapted to environment reproduce more successfully
• Finite resources lead to competition and survival of the fittest
• Example: Antibiotic-resistant bacteria

Classification Systems

• Modern systems focus on genetic history rather than just physical traits
• Use of dichotomous keys and cladograms to determine relationships

Conclusion

• Review of essential topics for biology EOC
• Importance of practice problems to solidify understanding
• Encouragement to review linked materials and practice tools