Life Sciences

Page 1: Living Organisms

  • Five Components of Life:

    • Must be made of cells (unicellular or multicellular)

    • Cells act as a protective barrier for living organisms

    • Reproduction: Capability to reproduce either sexually or asexually, leading to the next generation

    • Growth and Development: Organisms grow and develop through stages, utilizing old material.

    • Energy Utilization:

      • Heterotrophic: Obtaining energy by consuming other organisms

      • Autotrophic: Energy from the sun (photoautotrophs) or chemical reactions (chemoautotrophs)

    • Response to Stimuli: Adaptation and responsiveness to environmental changes are vital for survival

    • Homeostasis: Maintaining stable internal conditions for life processes

  • Cell Membranes:

    • Defined by a lipid bilayer

    • Prokaryotic vs Eukaryotic Cells:

      • Prokaryotic: No nucleus, free-floating DNA

      • Eukaryotic: Has a nucleus, organized DNA in lipid bilayer

  • Organelles: Includes endoplasmic reticulum, ribosomes, and Golgi bodies.

Page 2: Reproduction

  • Types of Reproduction:

    • Asexual Reproduction:

      • Produces clones (e.g., bacteria), no genetic variation

      • Vegetative Reproduction: A form of asexual reproduction in plants

    • Sexual Reproduction:

      • Involves two parents sharing genetic information resulting in new genetic combinations

      • Encourages adaptability to environmental changes

  • Metamorphosis: Two types:

    • Complete Metamorphosis:

      • Involves several life stages: egg, larva, pupa, adult

    • Incomplete Metamorphosis:

      • Organism remains similar throughout life stages

Page 3: Metabolism

  • Overview of Metabolism:

    • Energy balance between catabolic and anabolic reactions

  • Catabolic Reactions:

    • Breakdown of complex molecules into simpler ones (e.g., glycolysis)

  • Anabolic Reactions:

    • Building of complex molecules from simpler ones, requires energy

  • Key molecules: Glucose, ADP, NAD+ in both prokaryotic and eukaryotic cells, along with ATP and NADH.

Page 4: Cellular Respiration

  • Energy Requirement: All organisms need energy for functions and obtain it from glucose by breaking down food molecules

  • Cellular Respiration Process:

    • Breakdown of glucose molecules releases energy stored in bonds

  • ADP and ATP:

    • Adenosine triphosphate (ATP), a vital energy carrier stored in phosphate bonds

    • ATP uses energy for life processes (e.g., reproduction, locomotion)

  • Electron Acceptors: Oxygen is the primary electron acceptor for aerobic respiration; anaerobic organisms may use sulfur or hydrogen.

Page 5: Steps of Cellular Respiration

  • Key Stages:

    • Glycolysis:

      • Occurs in the cytoplasm; produces pyruvic acid

    • Krebs Cycle:

      • Occurs in mitochondria, requires oxygen and releases ATP and other byproducts

  • Aerobic vs Anaerobic:

    • Aerobic respiration relies on oxygen, whereas anaerobic respiration does not, resulting in less energy production

  • Electron Transport Chain (ETC):

    • Final stage of aerobic respiration producing about 28 ATP per glucose molecule

    • Oxygen acts as the final electron acceptor, producing water as a waste product.

Page 6: Adenosine and Energy Transfer

  • Adenosine:

    • Consists of a nitrogen base, ribose sugar, and three phosphate groups

    • Stores usable energy similar to a battery

  • Glycolysis:

    • Converts glucose into pyruvate, generating ATP and NADH

  • Energy Release: Electron transport releases energy, pumping protons out.

Page 7: Types of Nucleic Acids and Viruses

  • Nucleic Acids:

    • DNA and RNA:

      • Carry genetic information necessary for life a Conta

  • Virus Structure:

    • Composed of proteins (capsid) and genetic material (DNA/RNA)

  • Host Range:

    • Viruses can only infect specific host species; they can undergo mutations.

  • Examples of Viruses: Chickenpox, polio, smallpox, HIV.