Cell Biology Overview

Cell Biology

• Cell Theory

  • All living organisms are composed of cells.
  • The cell is the basic unit of life.
  • All cells arise from pre-existing cells.

• Types of Cells

  • Prokaryotic: Lack a nucleus, smaller in size (e.g., bacteria).
  • Eukaryotic: Have a nucleus and organelles, larger (e.g., plant and animal cells).

• Cell Organelles

  • Nucleus: Contains genetic material (DNA).
  • Mitochondria: Powerhouse of the cell, site of ATP production.
  • Ribosomes: Sites of protein synthesis.
  • Endoplasmic Reticulum (ER):
    • Rough ER: Studded with ribosomes; involved in protein synthesis.
    • Smooth ER: Lacks ribosomes; involved in lipid synthesis and detoxification.
  • Golgi Apparatus: Modifies, sorts, and packages proteins and lipids.
  • Lysosomes: Contain enzymes for digestion.
  • Cell Membrane: Semi-permeable barrier that regulates entry and exit of substances.

• Cell Division

  • Mitosis: Process of cell division for growth and repair, resulting in two identical daughter cells.
  • Meiosis: Specialized form of cell division that leads to the production of gametes (sperm and egg); involves two rounds of division.

• Cell Communication

  • Signaling pathways: Cells communicate via chemical signals (hormones, neurotransmitters).
  • Receptors: Proteins on cell surfaces that bind to signaling molecules.

Genetics

• DNA Structure

  • Composed of nucleotides (adenine, thymine, cytosine, guanine).
  • Double helix structure, held together by base pairing (A-T, C-G).

• Genes and Chromosomes

  • Genes: Segments of DNA that code for proteins.
  • Chromosomes: Structures that organize DNA; humans have 46 chromosomes (23 pairs).

• Mendelian Genetics

  • Principles of inheritance discovered by Gregor Mendel:
    • Law of Segregation: Alleles segregate during gamete formation.
    • Law of Independent Assortment: Genes for different traits are inherited independently.

• Genetic Variation

  • Sources of variation include mutations, sexual reproduction, and genetic recombination.

• Biotechnology in Genetics

  • DNA Cloning: Creating copies of DNA segments.
  • CRISPR: A gene-editing technology that allows for precise modifications of the genome.
  • Genetic Testing: Identifies mutations associated with genetic disorders.

• Population Genetics

  • Study of genetic variations within populations and how they change over time.
  • Key concepts: Allele frequency, Hardy-Weinberg equilibrium, genetic drift, and natural selection.

Cell Biology

• Cell Theory posits that all living organisms consist of cells, with the cell serving as the fundamental unit of life, and that all cells originate from pre-existing cells.
• Types of Cells
  • Prokaryotic cells are smaller, lack a nucleus, and include organisms such as bacteria.
  • Eukaryotic cells are larger, contain a nucleus and organelles, and can be found in plants and animals.
• Cell Organelles
  • Nucleus: Stores genetic material (DNA).
  • Mitochondria: Often referred to as the powerhouse of the cell, responsible for ATP production.
  • Ribosomes: Sites where protein synthesis occurs.
  • Endoplasmic Reticulum (ER):
    • Rough ER is covered with ribosomes and plays a crucial role in protein synthesis.
    • Smooth ER is ribosome-free and focuses on lipid synthesis and detoxification processes.
  • Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for transport.
  • Lysosomes: Organelles that contain digestive enzymes to break down waste materials.
  • Cell Membrane: A semi-permeable barrier that regulates the entry and exit of substances, maintaining homeostasis.
• Cell Division
  • Mitosis: A process that enables growth and repair, producing two identical daughter cells.
  • Meiosis: A specialized division that creates gametes (sperm and egg), involving two successive division rounds.
• Cell Communication
  • Cells utilize signaling pathways to communicate through chemical signals like hormones and neurotransmitters.
  • Receptors are proteins on cell surfaces that interact with these signaling molecules.

Genetics

• DNA Structure
  • DNA is made up of nucleotides, specifically adenine (A), thymine (T), cytosine (C), and guanine (G), and forms a double helix held together by base pairing (A with T, C with G).
• Genes and Chromosomes
  • Genes are segments of DNA coding for proteins, while chromosomes organize DNA; humans have 46 chromosomes, arranged in 23 pairs.
• Mendelian Genetics
  • Gregor Mendel established key inheritance principles:
    • Law of Segregation: Alleles separate during the formation of gametes.
    • Law of Independent Assortment: Genes for different traits are inherited independently of one another.
• Genetic Variation
  • Variation arises from mutations, sexual reproduction, and genetic recombination.
• Biotechnology in Genetics
  • DNA Cloning: Involves creating replicas of DNA segments.
  • CRISPR: A frontier editing technology that allows for targeted changes to the genome.
  • Genetic Testing: Techniques used to identify mutations linked to genetic disorders.
• Population Genetics
  • This field studies genetic variations within populations, focusing on changes over time, including concepts like allele frequency, Hardy-Weinberg equilibrium, genetic drift, and natural selection.