Study sheet: General Biology 1 Midterm Review

📋 Course Outline

1. Origin and Characteristics of Life
2. Cell Theory and Its Applications
3. Prokaryotic and Eukaryotic Cells
4. Cell Organelles and Functions
5. Bacterial Cell Wall Classification
6. Cell Modifications and Specialization

📖 1. Origin and Characteristics of Life

🔑 Key Concepts & Definitions

• Homeostasis : an organism’s ability to maintain a stable internal environment despite changes in the external environment
• Metabolism : all chemical processes that occur within an organism to sustain life and provide energy and materials for growth, reproduction, and maintenance

★ Must-know

• Life emerged approximately 3.5 billion years ago.

📌 Abiogenesis or spontaneous generation proposes that life originates from non-living matter, whereas biogenesis proposes that life originates from pre-existing life.

• Reproduction is the biological process by which organisms produce offspring sexually or asexually.

• Viruses are considered non-living because they lack cellular structures and cannot independently carry out homeostasis or metabolism.

Further detail

• Panspermia is the idea that life came from space on meteorites.

• Prions are non-living because they lack nucleic acids and cellular structures.

• JCVI-syn3.0 is considered living because it can grow, divide, and carry out metabolism despite being constructed artificially in a laboratory.

💡 Memory Hook

Abiogenesis begins with nonliving matter; biogenesis begins with pre-existing life.

📖 2. Cell Theory and Its Applications

🔑 Key Concepts & Definitions

• Cell theory : the cell is the basic unit of structure for all organisms, all organisms consist of one or more cells, and all cells arise only from pre-existing cells

★ Must-know

• Matthias Schleiden proposed that all plant tissues are composed of cells, while Theodor Schwann proposed that all animal tissues are composed of cells.

• Cells contain hereditary information that is passed from cell to cell, cells of a particular species have the same chemical composition, and all metabolic and physiological activities occur within cells.

Further detail

• Robert Hooke examined thin slices of cork with a microscope capable of 30× magnification, coined the term cell from the Latin cellulae meaning little room, and published Micrographia.

• Antonie van Leeuwenhoek developed a microscope capable of 300× magnification and was the first to observe living cells, which he called animalcules.

💡 Memory Hook

Hooke names cells, Leeuwenhoek sees living cells, Schleiden studies plants, Schwann studies animals, Virchow explains their origin.

📖 3. Prokaryotic and Eukaryotic Cells

★ Must-know

📌 Prokaryotic cells are smaller and contain a nucleoid rather than a nucleus, whereas eukaryotic cells are larger and contain a nucleus and membrane-bound organelles.

• All cells share:
  • DNA
  • a cell membrane
  • cytoplasm
  • ribosomes

Further detail

• Bacteria are living organisms because they divide by binary fission and pass DNA to new cells.

💡 Memory Hook

Prokaryotes have a nucleoid and no nucleus; eukaryotes have a nucleus and membrane-bound organelles.

📖 4. Cell Organelles and Functions

🔑 Key Concepts & Definitions

• Cell membrane : regulates the entrance and exit of substances in a cell

★ Must-know

• Ribosomes carry out protein synthesis, while the nucleolus produces ribosomes.

• Mitochondria produce ATP through cellular respiration.

• The Golgi body modifies, sorts, and packages proteins and lipids and produces vesicles, lysosomes, and vacuoles.

Further detail

• The smooth endoplasmic reticulum synthesizes lipids and detoxifies drugs and poisons.

• Lysosomes contain hydrolytic digestive enzymes called lysozymes and destroy nonfunctional organelles and cells.

• Peroxisomes contain oxidative enzymes for breaking down fatty acids and alcohol.

• The cytoskeleton maintains a cell’s shape and provides dynamic support, while the cell wall maintains shape and protects the cell.

💡 Memory Hook

Imagine a cell as a factory: the nucleus directs, ribosomes build, the ER processes, the Golgi packages, and mitochondria supply energy.

📖 5. Bacterial Cell Wall Classification

★ Must-know

📌 Gram-positive bacteria have a thicker peptidoglycan layer and stain purple, whereas Gram-negative bacteria stain red, have a thinner peptidoglycan layer and an additional membrane, and are typically more resistant to antibiotics.

Further detail

• Vibrio cholerae is Gram-negative because it gives a red stain and has an additional membrane layer.

• Staphylococcus aureus is Gram-positive because it gives a purple stain and has thick peptidoglycan.

💡 Memory Hook

Gram-positive bacteria stain purple with thick peptidoglycan; Gram-negative bacteria stain red and have an additional membrane.

📖 6. Cell Modifications and Specialization

🔑 Key Concepts & Definitions

• Cell modification : a structural specialization in which structure defines function and enables different cells to perform different roles

★ Must-know

• Ciliated cells secrete mucus and move foreign materials out of the body to protect an organ.

• Neurons have branching extensions from the cyton and soma, including axonic and dendritic terminals, that allow cell-to-cell communication.

• Red blood cells have flexible membranes and a shape that lessens diffusion distance, increasing oxygen-carrying capacity.

Further detail

• Anucleate cells lose their nucleus through modification to perform specialized functions.

• Sperm cells have a midpiece rich in mitochondria for energy and an acrosome that protects the male gamete’s genetic material.

• Phagocytes use pseudopodia to reach and engulf foreign bodies.

• Intercalated discs in cardiac muscle allow cell-to-cell communication.

💡 Memory Hook

Structural modification → specialized function.

📊 Synthesis Tables

Prokaryotic and Eukaryotic Cells

Feature	Prokaryotic cells	Eukaryotic cells
Size	Smaller	Larger
Genetic region	Nucleoid	Nucleus
Membrane-bound organelles	Absent	Present
Examples	Bacteria	Plant and animal cells

Gram-Positive and Gram-Negative Bacteria

Feature	Gram-positive	Gram-negative
Stain color	Purple	Red
Peptidoglycan	Thick	Thin
Additional membrane	Absent	Present
Antibiotic resistance	Typically lower	Typically higher