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Foundations of General Biology: Study Guide

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Introduction to Biology

Definition and Scope

Biology is the scientific study of life, encompassing the structure, function, growth, origin, evolution, and distribution of living organisms.

  • Bio = study of life

Levels of Biological Organization

Hierarchical Structure

Biological systems are organized into a hierarchy, from the broadest to the most specific levels:

  1. Biosphere

  2. Ecosystem

  3. Communities

  4. Population

  5. Organisms

  6. Organs and organ systems

  7. Tissues

  8. Cells

  9. Organelles

  10. Molecules

Characteristics of Life

Defining Features

All living things share certain characteristics that distinguish them from non-living matter:

  • DNA: Genetic material that stores information.

  • Cells: Basic unit of structure and function.

  • Energy and Metabolism: Ability to obtain and use energy.

  • Reproduction:

    • Sexual: Involves two parents and the combination of genetic material.

    • Asexual: Involves one parent; offspring are genetically identical.

      • Mitosis: Cell division in eukaryotes.

      • Binary fission: Used by bacteria.

      • Budding: Used by fungi.

  • Homeostasis: Regulation of internal environment.

  • Growth and Development: Increase in size and complexity.

  • Response to Stimuli: Ability to react to environmental changes.

Cells: The Basic Unit of Life

Cell Structure and Function

Cells are the fundamental units of life, with structure and function closely linked.

  • All cells have a membrane.

  • Energy molecule: ATP (produced by cellular respiration in mitochondria).

  • Gametes (sperm and egg) each have 23 chromosomes in humans.

Types of Cells

  • Eukaryotic cells: Have membrane-enclosed organelles, including a DNA-containing nucleus.

  • Prokaryotic cells: Lack a nucleus and other membrane-bound organelles; generally smaller than eukaryotic cells.

Cell Organelles

Key organelles and their functions in plant and animal cells:

  • Plant Cell:

    • Chloroplast

    • Cell Wall

    • Amyloplast

    • Vacuole

    • Golgi Vesicles

    • Golgi Apparatus

    • Membrane

    • Peroxisome

    • Cytoplasm

    • Ribosomes

    • Nucleus

    • Nucleolus

    • Rough ER

    • Smooth ER

    • Mitochondrion

    • Cytoskeleton

  • Animal Cell:

    • Lysosome

    • Centrosome

    • Golgi Vesicles

    • Golgi Apparatus

    • Membrane

    • Peroxisome

    • Cytoplasm

    • Ribosomes

    • Nucleus

    • Nucleolus

    • Rough ER

    • Smooth ER

    • Mitochondrion

    • Cytoskeleton

DNA and Genetic Information

Structure and Function

  • DNA holds hundreds to thousands of genes.

  • Directs cell development and function.

  • Four chemical building blocks: A (adenine), C (cytosine), T (thymine), G (guanine).

  • Chromosomes are made of DNA.

  • Genes are units of inheritance passed from parents to offspring.

  • In RNA, U (uracil) replaces T (thymine).

Gene Expression

  • DNA provides blueprints for making proteins.

  • Genes control protein production indirectly, using RNA as an intermediary.

  • Gene expression is the process of converting information from gene to cellular product (protein synthesis).

Cell Division and Reproduction

Mitosis

Mitosis is the process of cell division in eukaryotic cells, resulting in two identical daughter cells.

  • Phases: Prophase, Metaphase, Anaphase, Telophase

Sexual Reproduction

  1. Sperm cell

  2. Fertilization

  3. Fertilized egg with DNA from both parents

  4. Embryo's cells with copies of inherited DNA

Energy and Matter in Living Systems

Transformation and Flow

  • Energy input, mainly from the sun, is transformed and transferred through ecosystems.

  • Photosynthetic organisms convert sunlight into chemical energy (sugars).

  • Chemical energy passes from producers to consumers.

  • Energy flows through ecosystems, entering as light and exiting as heat.

  • Chemical elements are recycled within ecosystems.

Interactions and Symbiosis

Organisms and Their Environment

  • Interactions can benefit both organisms, harm both, or benefit one and harm the other.

  • Symbiotic relationships:

    • Commensalism: Win/Unaffected

    • Mutualism: Win/Win

    • Parasitism: Win/Lose

Theories in Biology

Scientific Theories

  • A theory explains a very general class of phenomena or observations.

  • Theories have two components:

    1. Pattern: Something that occurs in the natural world.

    2. Process: Responsible for creating the pattern.

  • Two foundational theories:

    • The cell theory

    • The theory of evolution by natural selection

The Cell Theory

  • First observed by Robert Hooke and Anton van Leeuwenhoek in the 1660s.

  • A cell is a highly organized compartment bounded by a plasma membrane.

  • States:

    • All organisms are made of cells (pattern).

    • All cells come from preexisting cells (process).

The Theory of Evolution by Natural Selection

  • Proposed by Charles Darwin and Alfred Russel Wallace in 1858.

  • Claims:

    1. All species are related by common ancestry (pattern).

    2. Species can be modified from generation to generation (process: descent with modification).

Evolution and Natural Selection

Overview

  • Adaptations are the result of evolution.

  • Example: Beach mouse's light, dappled fur acts as camouflage; inland mice are darker to match their environment.

Fitness and Adaptation

  • Fitness: Ability to produce offspring.

  • Individuals with high fitness produce more surviving offspring.

Darwin's Observations and Inferences

  • Individuals in a population vary in traits, many of which are heritable.

  • More offspring are produced than survive; competition is inevitable.

  • Species generally suit their environment.

  • Individuals best suited to their environment are more likely to survive and reproduce (natural selection).

  • Over time, advantageous traits become more common in the population.

Differential Reproductive Success

  • Evolution occurs when heritable variation leads to differences in reproductive success.

The Tree of Life

Phylogeny and Speciation

  • All species trace back to a single common ancestor.

  • Speciation: The process by which populations diverge to form new species.

  • The tree of life depicts genealogical relationships among species.

  • Phylogeny: The actual genealogical relationships among all organisms.

Phylogenetic Trees

  • Show evolutionary relationships; branch points indicate divergence from a common ancestor.

Taxonomy and Classification

Taxonomy

  • Taxonomy is the effort to name and classify organisms.

  • A taxon is a named group.

  • Modern taxonomy uses three domains: Bacteria, Archaea, and Eukarya.

  • A phylum is a major lineage within a domain.

Linnaean System

  • Established by Carolus Linnaeus in 1735.

  • Each organism is given a unique scientific name.

Comparison of Prokaryotes and Eukaryotes

Feature

Prokaryotes

Eukaryotes

Nucleus

Absent

Present

Membrane-bound organelles

Absent

Present

Size

Generally smaller

Generally larger

Examples

Bacteria, Archaea

Plants, Animals, Fungi, Protists

Summary

This guide covers the foundational concepts of general biology, including the characteristics of life, cell structure and function, genetic information, energy flow, evolution, and classification systems. Understanding these principles is essential for further study in biological sciences.

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