🧬

Biology and Genetics Overview

Jun 4, 2025

Biology and Genetics Lecture Notes

Reproduction and Genetics

  • Variety of Genes: Creates mutations.
  • Cell Division:
    • 4 cells form, each taking chromosomes from two sources.
    • Autosomes: Essential information, paired #1-22, same gene type aligned.
    • Two rounds lead to four daughter cells with haploid numbers.
    • Diploid (2n): Full set of chromosomes, somatic.
    • Haploid (n): Half the number, sex cells.
    • Egg production results in one viable egg, three non-functional polar bodies.

Process of Meiosis

  • Prophase I: Homologous chromatids exchange genes.
  • Metaphase I: Homologous pairs align in the center.
  • Anaphase I: Separation towards centrioles.
  • Telophase I: Two haploid cells, chromosome numbers differ.
  • Prophase II: Nucleus dissolves, spindle forms.
  • Metaphase II: Chromosomes line up in the middle.
  • Anaphase II: Chromosomes separate.
  • Telophase II: Membrane pinches, different genes in each.

Asexual vs Sexual Reproduction

  • Asexual: One parent, less energy, no genetic variety.
  • Sexual: Greater variety, harder for species survival.

Genetics

  • Genetics: Transmission of characteristics from parents to offspring.
  • Gregor Mendel: Studied genetics using pea plants.
  • Traits: Inherited characteristics.
  • Genes and Alleles:
    • Genes are DNA segments for specific traits.
    • Alleles are different versions of a gene.
    • Dominant Alleles: Always expressed if present.
    • Recessive Alleles: Only expressed if no dominant present.

Mendelian Experiments

  • Punnett Square: Predicts genetic outcomes.
  • Principle of Segregation: Alleles separate during meiosis.
  • Independent Assortment: Traits are inherited independently.

Genetic Disorders and Patterns

  • Recessive Disorders: Only expressed if homozygous recessive.
  • Dominant Disorders: Less common in heterozygous.
  • Pedigrees: Family history diagrams tracing traits.
  • Incomplete Dominance: Phenotypic blending of genes.
  • Codominance: Heterozygotes express both alleles fully.
  • Multiple Alleles: Traits from more than two alleles.
  • Sex-linked Traits: Often X-linked, e.g., hemophilia and color blindness.

Genetic Expression and Regulation

  • DNA and RNA:
    • DNA is missing oxygen, double-stranded.
    • RNA is single-stranded, uracil instead of thymine.
    • Proteins are made based on DNA instructions.
    • mRNA, rRNA, tRNA: Different forms of RNA with specific functions in protein synthesis.

Operons in Gene Regulation

  • Operon: Regulatory system for gene expression in prokaryotes.
  • Components:
    • Promoter: RNA Polymerase binding site.
    • Operator: On/off switch.
    • Repressor: Protein blocking synthesis.
    • Structural Genes: Code for proteins.
  • Inducible and Repressible Operons: Enzyme production regulation based on need.

Evolutionary Biology

  • Natural Selection: Descent with modifications.
  • Darwin's Principles:
    • Genetic variation exists.
    • Traits can be inherited.
    • More offspring produced than can survive.
    • Traits that enhance survival are favored.
  • Fossil Record: Provides evidence of evolution.

Taxonomy and Classification

  • Taxonomy: Naming and classification of organisms.
  • Linnaeus System: Seven levels based on structure.
  • Binomial Nomenclature: Scientific naming of species.

Human Body Systems Overview

Endocrine System

  • Glands secrete hormones, e.g., pituitary (growth), pancreas (insulin).

Integumentary System

  • Protects body, main organ: skin with multiple layers.
  • Controls temperature and synthesizes vitamin D.

Digestive System

  • Processes food through mechanical and chemical digestion.
  • Key organs include mouth, stomach, intestines, pancreas, and liver.

Skeletal System

  • Functions: support, protection, blood cell production, movement.
  • Types of joints: ball/socket, pivot, hinge, etc.

Immune System

  • Lymphocytes, B cells, T cells, and their roles in immunity.
  • Vaccines train the immune system.

Excretory System

  • Kidneys filter blood, secrete waste, and maintain homeostasis.

Muscular System

  • Types of muscles: skeletal, smooth, cardiac.
  • Myofibrils and muscle fibers.

Nervous System

  • Units: neurons consist of dendrites, axons, neurotransmitters.
  • CNS and PNS (including autonomic and sympathetic systems).

Circulatory System

  • Circulation of blood through arteries, capillaries, and veins.
  • Heart chambers and components of blood.

Respiratory System

  • Involves exchange of gases through structures like alveoli.