Cellular Energy and Division: Key Biological Processes

Posted on Feb 1, 2026 in Biology

Cellular Energy and Division Concepts

I. Energy Transformations: Photosynthesis and Respiration

Plant Mass Origin

  • Explain where plants get their mass: Air / carbon dioxide.

Complementary Pathways

  • Explain how photosynthesis and cellular respiration are complementary pathways: The products of photosynthesis are the reactants of cellular respiration, and the products of cellular respiration are the reactants of photosynthesis. This forms a cycle.

Energy Carriers

  • List the energy carriers created and used in photosynthesis and cellular respiration (3 or 4 main ones): ATP, NADPH, NADH. (FADH2 is often included but omitted here as requested).

Products of Key Processes

  1. Identify what is generated (produced) in the following processes and where they occur:
    • Light reactions of photosynthesis: Energy carriers (Location: Thylakoids)
    • Calvin cycle of photosynthesis: Glucose (Location: Cytoplasm)
    • Glycolysis: Pyruvate (Location: Cytoplasm)
    • Fermentation (yeast and human): Alcohol (yeast); Lactic acid (humans) (Location: Cytoplasm)
    • Kreb’s Cycle of cellular respiration: Energy carriers (Location: Mitochondria)
    • Oxidative Phosphorylation of cellular respiration: Lots of ATP (Location: Mitochondria)

Process Locations

  • Identify where each of the above processes takes place (See list above for locations).

Light Reactions Explained

  • Explain what occurs in the light reactions of photosynthesis: Light energizes electrons. Electrons allow for the splitting of water and the formation of energy carriers.

Stages of Cellular Respiration

  • List the stages of cellular respiration in order: Glycolysis / Kreb Cycle / Oxidative Phosphorylation.

Aerobic vs. Anaerobic

  • Explain the difference between anaerobic and aerobic reactions, and identify which processes in cellular respiration are anaerobic and aerobic: Anaerobic means no oxygen; Aerobic means with oxygen. Oxidative Phosphorylation is aerobic.

Role of Oxygen

  • Explain how oxygen is used in cellular respiration: Oxygen increases the output of ATP by acting as the final electron acceptor.

Enzyme Catalysis

  • Define “enzyme catalyzed reaction” and list examples: Proteins that lower the energy required to start a reaction, thus speeding up the reaction.

II. Cell Reproduction and Genetics

Methods of Cell Division

  • Explain the methods for making new cells:
    • Binary Fission: Single-celled organisms.
    • Mitosis: Multicellular organisms and eukaryotic single-celled organisms.
    • Meiosis: Sexual reproduction in multicellular organisms.
  • Which organisms use which methods (See list above).

The Cell Cycle Phases

List the phases of the cell cycle in order:

  1. Interphase: Cell prepares to divide.
  2. G0: A cell remains the same, but continues to carry out its normal functions.
  3. G1: The cell grows in size.
  4. S: DNA is replicated, resulting in two copies of the entire genome.
  5. G2: Checks to make sure everything is ready for division.
  6. Mitosis or Meiosis: DNA is separated.
  7. Cytokinesis: Parent cell physically splits into two daughter cells.
  • Explain what occurs in each phase (See descriptions above).

Mitosis Phases

  • List the phases of mitosis in order: Prophase / Metaphase / Anaphase / Telophase.

Chromosomes Defined

  • Define “karyotype”: A picture of your chromosomes.
  • Define “autosome”: Regular chromosomes that contain genetic information for normal body development and regulation. In humans, there are 22 pairs of autosomes.
  • Define “sex chromosome”: Chromosomes that determine the sex of the organism (Male or Female / X or Y).

Mitosis vs. Meiosis

  • Explain the differences between mitosis and meiosis: Difference in the number of daughter cells produced and how the DNA differs (Mitosis produces identical diploid cells; Meiosis produces genetically unique haploid cells).

Chromosome Calculation

  • Calculate how many chromosomes will be in the daughter cells after mitosis and meiosis given the number of chromosomes in the parent cell (Requires specific parent cell number input).

Sexual Reproduction Advantage

  • Explain the advantage of meiosis and sexual reproduction: Increases genetic diversity.

III. Cell Regulation and Disease

Programmed Cell Death

  • Define “Apoptosis”: Programmed cell death (a necessary and beneficial process).

Growth Regulators

  • Explain the function of positive and negative growth regulators:
    • Positive: Encourage cell growth and division (Ex: Human Growth Hormone).
    • Negative: Prompt apoptosis or limit cell growth and division (Ex: Tumor Suppressor Genes).

Genetics and Cancer Link

  • Explain the link between genetics (genes) and cancer: Genes do not directly cause cancer, but mutations in specific genes increase the risk factor.

Tumor Suppressor Gene Functions

  • List the things that tumor suppressor genes code for:
    • Inhibiting the cell cycle.
    • Stimulating repair of damaged DNA.
    • Promoting cell adhesion.
    • Preventing cells from breaking off and metastasizing.
    • Enforcing anchorage dependence (cells can normally only survive when attached to other cells).
    • Preventing the formation of new blood vessels (anti-angiogenesis).
    • Triggering apoptosis.

Cancer Treatments

  • List the treatments for cancer:
    • Surgery, Radiation, and Chemotherapy (using targeted bursts to kill cancer cells).
    • Cryosurgery (Using cold to kill cancer cells).
    • Hormone therapy (Can slow or stop cancer cells from dividing; only works on certain cancers like breast or prostate).

Mutagens

  • List the external agents (mutagens) which cause DNA mutations:
    • Chemical mutagens.
    • Ionizing radiation (UV, X-Rays, other high-energy radiation).
    • Viruses.
    • Chronic injury.
    • Lifestyle factors (Diet, exercise).

Avoidable Risk Factors

  • List the avoidable risk factors for developing cancer (Implied: many listed under mutagens/lifestyle).

Cancer Cell Characteristics

  • Explain how cancer cells differ from normal cells:
    • Divide rapidly.
    • Are functionally immortal.
    • Do not die when they should.
    • Continue to divide indefinitely.

Henrietta Lacks Significance

  • Explain the significance of Henrietta Lacks’ tumor cells (HeLa cells): They continue to divide and grow indefinitely in culture and are still being studied to this day.