AP Biology Unit 4

AP Biology Unit 4 Study Guide

Chapter 11

• Cell Signaling Types: Cell signaling is how cells communicate with each other. There are two main types:

  • Local Signaling: This happens when cells communicate over short distances. Examples include growth factors that affect nearby cells.

  • Long-Distance Signaling: This is when signals are sent over greater distances, often using hormones that travel through the bloodstream.

• Hormones: Hormones are chemical messengers produced by glands in the body. They help regulate various functions, like growth, metabolism, and mood.

• Reception, Transduction, Response:

  • Reception: The target cell detects a signal molecule (ligand) when it binds to a receptor.

  • Transduction: The signal is converted into a form that can produce a cellular response. This often involves a series of steps called a signal transduction pathway.

  • Response: The cell responds to the signal, which could include activating genes, creating proteins, or altering metabolism.

• Signal Transduction Pathway: A sequence of processes where a signal outside the cell is converted into a functional response inside the cell.

• Ligand: A molecule that binds to a receptor to trigger a response in the cell.

• Receptors:

  • G-Protein-Coupled Receptors: These are receptors that activate when a ligand binds, causing the receptor to change shape and activate a G-protein inside the cell, leading to a response.

  • Receptor Tyrosine Kinases: These receptors attach phosphate groups to tyrosine (an amino acid) on proteins, which can initiate multiple signaling pathways at once.

  • Ligand-Gated Ion Channels: When a ligand binds to these channels, they open to allow ions to flow into the cell, leading to changes in cell activity.

• Intracellular Receptors: These receptors are located inside the cell and usually bind to small, non-polar molecules (like steroid hormones) that can pass through the cell membrane.

• Protein Kinases and Phosphorylation Cascade:

  • Protein Kinases: Enzymes that add phosphate groups to proteins, which can activate or deactivate them.

  • Phosphorylation Cascade: A series of events where one protein kinase activates another, amplifying the original signal.

• Protein Phosphatases: Enzymes that remove phosphate groups from proteins, turning off signals.

• Secondary Messengers: Small molecules (like cAMP) that relay signals inside the cell and amplify the response.

• cAMP: A common secondary messenger that helps transmit signals from cell surface receptors.

• Transcription Factors: Proteins that help control which genes are turned on or off in a cell during the response.

• Cell Regulation: Cells can regulate signals to turn responses on or off as needed.

• Diverse Effects from One Ligand: One ligand can cause different responses depending on the cell type and the signaling pathway activated.

• Scaffolding Proteins: They provide a framework for various signaling molecules to be organized in a way that enhances signaling efficiency.

• Apoptosis: A process of programmed cell death that is vital for development and maintaining health by removing unnecessary or damaged cells.

Chapter 12

• Cell Division: This is crucial for reproduction (creating offspring), growth (increasing body size), and repair (fixing damaged tissues).

• Genome Structure:

  • Prokaryotes: Have a single circular chromosome without a nucleus.

  • Eukaryotes: Have multiple linear chromosomes contained within a nucleus.

• Chromatid vs. Chromosome:

  • Chromatid: One half of a duplicated chromosome.

  • Chromosome: A structure made of DNA and proteins that contains genetic information.

• Cell Cycle Phases:

  • G1 Phase: Cell grows and prepares for DNA replication.

  • S Phase: DNA is replicated, forming sister chromatids.

  • G2 Phase: Cell prepares for mitosis, continuing to grow and making proteins.

  • M Phase: The phase where mitosis occurs, dividing the cell's nucleus and contents.

• Mitosis Phases:

  • Prophase: Chromosomes condense, and spindle fibers begin to form.

  • Metaphase: Chromosomes line up at the cell's equator.

  • Anaphase: Sister chromatids are pulled apart to opposite poles.

  • Telophase: Nuclear membranes form around the separated chromatids, which become less condensed.

• Spindle Apparatus: A structure made of microtubules that helps separate chromosomes during cell division.

• Chromosome Movement: Chromosomes move toward the cell's center during metaphase and then toward the poles during anaphase as the cell elongates.

• Centrioles and Centrosomes: Structures that help organize the spindle apparatus during cell division.

• Cytokinesis: The division of the cytoplasm, which occurs differently in plants (forming a cell plate) and in animals (forming a cleavage furrow).

• Motor Proteins: Proteins that help move chromosomes and other structures within cells.

• Bacterial vs. Eukaryotic Division: Bacterial cells divide by binary fission, a simpler process than eukaryotic mitosis.

• Binary Fission and Mitosis Origins: The simplicity of binary fission may resemble early forms of mitosis in eukaryotes.

• Cytoplasmic Signals: These are signals within the cell that influence various processes, including cell growth and division.

• Cell Cycle Checkpoints: Points in the cycle that monitor progress and ensure everything is ready for the next phase; they prevent uncontrolled cell division.

• Roles of cdk and mpf: Cyclin-dependent kinases (cdk) and maturation-promoting factor (mpf) help control the progression of the cell cycle.

• Growth Factors: These are proteins that stimulate cell division and growth.

• Density-Dependent Inhibition: Cells stop dividing when they are crowded.

• Anchorage Dependence: Normally, cells need to be attached to a surface to divide.

• Cancer Growth vs. Normal Growth: Cancer cells grow uncontrollably, ignoring signals that regulate the cell cycle.

• Bacterial and Eukaryotic Chromosomes: Both types of cells have chromosomes that carry genetic information for replication.

• Tubulin and Actin Roles: Tubulin forms microtubules, which are important for cell shape and division. Actin helps with muscle contraction and other movements.

• Tumor Types:

  • Benign Tumors: Non-cancerous and don’t spread.

  • Malignant Tumors: Cancerous and can spread to other parts of the body (metastasize).

Chapter 40

• Anatomy vs. Physiology: Anatomy is the study of body structures, while physiology is the study of how those structures function.

• Evolution and Animal Size/Shape: Evolution influences how animals adapt in size and shape to survive in their environments.

• Body Organization: The body is organized at multiple levels, starting from cells, tissues, organs, and systems.

• Four Main Tissue Types:

  • Epithelial Tissue: Covers and protects surfaces.

  • Connective Tissue: Supports and binds other tissues (like bone, blood).

  • Muscle Tissue: Responsible for movement.

  • Nervous Tissue: Transmits signals throughout the body.

• System Differences: Different systems (like circulatory, respiratory, digestive) have specific functions.

• Homeostasis Concepts:

  • Regulator: Maintains internal stability regardless of external changes.

  • Conformer: Adjusts to the external environment.

  • Homeostasis: Maintaining a stable internal environment.

  • Set Point: The ideal value for a variable (like temperature).

  • Stimulus/Response: Changes in the environment (stimulus) trigger an adjustment (response).

  • Feedback Loops: Negative feedback reduces output, while positive feedback increases it.

  • Circadian Rhythm: Biological processes that follow a 24-hour cycle (like sleep-wake patterns).

  • Acclimatization: Short-term adjustment to environmental changes, while adaptation involves long-term changes.

• Thermoregulation: Maintaining body temperature through methods like sweating or shivering.

• Endothermic vs. Ectothermic:

  • Endothermic: Animals that generate their own heat (like mammals).

  • Ectothermic: Animals that rely on external sources for heat (like reptiles).

• Integumentary System: The system that includes skin, hair, and nails, which protects the body and regulates temperature.

• Counter-Current Exchange: A system where fluids flow in opposite directions to maximize heat exchange (like in fish gills).

• Hypothalamus: A brain region that helps regulate homeostasis, including temperature and hunger.

• Bioenergetics: The study of how energy flows through living systems.

• Metabolic Rate: The rate at which your body uses energy (calories). It can be measured to understand energy expenditure.

• Types of Metabolic Rate:

  • Basal Metabolic Rate (BMR): Energy used at rest in a neutrally temperate environment.

  • Total Daily Energy Expenditure: Total energy used in a day, including all activities.

• Activity Effects on Metabolic Rate: Physical activities can increase metabolic rate as more energy is used for movement and processes.