Biology Unit 3: Life Processes and Cell Function

Life Processes, Microscope & Cell Structure and Function - Unit 3

• Topic: Defining Life
• Aim: Differentiating between living and nonliving things
• Biology: The study of life and living things.
• Homeostasis: Maintaining a stable internal environment despite external changes. Dynamic equilibrium.
• Life Functions: All living things must maintain homeostasis by carrying out 8 basic life functions.
• Nutrition: Obtaining and processing food.
  • Autotrophic: Organisms making their own food.
  • Heterotrophic: Organisms depending on other organisms for food.
  • Ingestion: Taking food.
  • Digestion: Breaking food into nutrients.
  • Absorption: Taking in nutrients.
  • Egestion: Eliminating waste.
• Transport: Absorbing and circulating materials throughout an organism.
  • Absorption: Nutrients and materials taken into cells and the bloodstream.
  • Circulation: Movement of materials to/from cells, within cells, and throughout an organism.
• Respiration (Cellular): Release of energy for life activities through chemical reactions.
  • Energy stored in food nutrients/organic molecules.
• Excretion: Removal of waste materials produced by cells.
  • Removal of metabolic wastes (e.g., urine, sweat, CO2, H2O).
• Regulation: Controlling and coordinating organism activities.
  • Responding to changes in the environment.
  • Stimulus: Change in internal or external environment of an organism.
  • Examples include finding food, avoiding danger, responding to light.
  • Nervous and endocrine systems are responsible for regulation.
  • Example: Hormone changes like quick reactions or blood sugar regulation.
• Synthesis: Producing complex substances from simpler substances.
  • Examples: Combining simple food molecules to form complex materials.
• Growth: Increase in size and/or number of cells.
  • Examples include various developmental stages.
• Reproduction: Production of new organisms.
  • Not necessary for the survival of an individual organism, but is necessary for the survival of the species.
• Metabolism: Sum total of all life processes.
  • Metabolic reactions constantly adjusted for homeostasis via regulation

Scientist Discoveries and the Cell Theory

• Topic: Scientist Discoveries and the Cell Theory
• Aim: How did the microscope influence biology?
• Zacharias Janssen: Late 1500s in Holland, created the first compound microscope using multiple lenses.
• Robert Hooke: 1665 in England, used a microscope to observe cork (a nonliving plant material) and coined the term "cells". First person to see "dead" cells.
• **Anton van Leeuwenhoek:**1665 in Holland, used a single lens microscope to observe pond water and saw tiny living organisms everywhere.
• Cell theory: Cells are the basic unit of all living things. Unicellular(bacteria, amoeba) and Multicellular organisms (animals, plants) are composed of cells.
  • New cells are produced only from pre-existing cells.
• Exceptions to the Cell Theory:
  • Viruses: Cannot reproduce on their own, require a host cell.
  • Mitochondria and Chloroplasts: Have their own DNA but are not considered cells.
  • The origin of the very first cell (abiogenesis) is not explained by the Cell Theory.

Microscope – Parts and Use

• Topic: Microscope
• Aim: How do scientists use a microscope to view organisms?
• Components of a Compound Light Microscope:
  • Eyepiece/Ocular: Magnification usually 10x.
  • Body Tube: Holds eyepiece over objective lens
  • Coarse Adjustment Knob: Focus under low power.
  • Fine Adjustment Knob: Produces small amounts of focus under high power for detail.
  • Nosepiece: Rotating part to switch objectives.
  • Objective Lenses: Magnification (e.g. 10x, 43x).
  • Stage: Place slide.
  • Stage Clips: Holds slide in place.
  • Diaphragm: Controls amount of light used.
  • Light Source: Supplies light for viewing specimens.
  • Arm: Supports body tube and connects to base
  • Base: Provides bottom support.
• Magnification: Eyepiece magnification x Objective lens magnification
• Carrying a Microscope: Use two hands: one hand on the arm and one hand on the base.
  • The procedures for proper microscope use are not included in these notes
• Preparing a Wet Mount Slide:
  • Place specimen on a slide.
  • Add a drop of water.
  • Gently place a coverslip at a 45° angle to avoid bubbles.
• Staining Procedure: To view detail:
  • Add stain to one side of the coverslip.
  • Use a paper towel to draw the stain under the coverslip to the specimen.

Cell Structure and Function

• Levels of Organization:

  • Organelle: Specialized structures within a cell (perform 8 basic life functions).
  • Cell: Basic unit of structure and function in living things.
  • Tissue: Group of similar cells performing a common function.
  • Organ: Group of different tissues performing a common function.
  • Organ system: Group of organs working together for a common function.

• Organism: Living thing with fully functional systems.

• Cell Types:

  • Prokaryotic: Cells lacking a nucleus or membrane-bound organelles (e.g., bacteria).
  • Eukaryotic: Cells with a nucleus and membrane-bound organelles (e.g., plant cells, animal cells).

• Cytoplasm: Watery fluid inside a cell, containing organelles, found between the cell membrane and the nucleus.

• Nucleus: Directs cell activities, contains DNA (genetic material). -Contains the nucleolus (site of ribosome synthesis) and nuclear pores (allow materials in and out)

• Vacuole: Fluid-filled sacs storing water, food, or wastes.

  • Animal cells have many small vacuoles.
  • Plant cells have fewer, larger vacuoles.

• Endoplasmic Reticulum (ER): Interconnected channels for material synthesis, storage, and transport within a cell: Rough ER has ribosomes, smooth ER doesn't.

  • Ribosomes: Sites of protein synthesis.

• Golgi apparatus: Stack of membrane-bound channels processing and transporting cell products. Like a post office.

• Mitochondria: Site of cellular respiration (energy production).

• Cell Membrane: Surrounds the cell, regulates passage of materials into and out of the cell (selectively permeable).

  • Composed of phospholipids and proteins

• Cell Wall: Rigid outer layer found in plant cells (mostly cellulose) for support.

• Chloroplast: Site of photosynthesis in plant cells. Contains chlorophyll (to capture light energy).

• Lysosome: Contains digestive enzymes, breaks down or eliminates damaged components in animal cells

• Centrioles: Involved in cell division in animal cells.

Similarities and Differences between Plant and Animal Cells

• Similarities: Both cells are eukaryotic. Both contain most of the same organelles.
• Differences: Plant cells have a cell wall and chloroplasts. Animal cells have lysosomes and centrioles. These specific parts are not present in plant cells.

Cell Transport

• Passive Transport: Movement of molecules without energy (ATP).

  • Diffusion: Movement of molecules from high concentration to low concentration.
  • Osmosis: Diffusion of water across a selectively permeable membrane.
  • Facilitated diffusion: Use of transport proteins to help larger molecules move across the cell membrane.

• Active Transport: Movement of molecules from low concentration to high concentration, requiring energy (ATP).

  • Phagocytosis: engulfing large solid food particles, part of active transport.

Osmosis and Environmental Conditions

• Isotonic: Equal water concentration inside and outside the cell. No net water movement.
• Hypotonic: Greater water concentration outside the cell. Water moves into the cell, causing swelling. Animal cells may burst; plant cells become turgid (normal).
• Hypertonic: Greater water concentration inside the cell. Water moves out of the cell, causing shrinking or shriveling. Animal cells shrink, plant cells plasmolyze.

Explore the fundamentals of life processes, including the essential functions that define living organisms. This quiz covers key concepts such as homeostasis, nutrition, and transport mechanisms within cells. Test your understanding of how living things maintain stability and function effectively in their environments.