Prokaryotic vs Eukaryotic Cells Quiz

Prokaryotic vs. Eukaryotic Cells

• Prokaryotic cells are single-celled organisms without a nucleus or membrane-bound organelles. Examples include bacteria.
• Eukaryotic cells have a nucleus and membrane-bound organelles. They can be single-celled, like yeast, or multicellular, like plants and animals.
• Key differences are size, complexity, and genetic material. Prokaryotes have circular DNA, eukaryotes have linear DNA.
• Prokaryotes reproduce asexually via binary fission, while eukaryotes can reproduce both asexually and sexually.

Plant vs. Animal Cells

• Plant cells have a rigid cell wall, chloroplasts for photosynthesis, and a large central vacuole, features absent in animal cells.
• Animal cells have lysosomes and centrioles that are not found in plant cells.
• Both share common organelles like the nucleus, mitochondria, and endoplasmic reticulum, but functions may differ based on the cell type.
• Plant cells can convert sunlight to energy using chloroplasts, a process that does not occur in animal cells.

Four Components of All Cells

• All cells contain a plasma membrane, cytoplasm, ribosomes, and genetic material (DNA or RNA).
• The plasma membrane controls what enters and exits the cell, maintaining internal balance (homeostasis).
• Cytoplasm is the gel-like substance where cell processes happen; it contains organelles and the cytoskeleton.
• Ribosomes synthesize proteins by translating genetic information.

Organelles: Definition and Functions

• Organelles are specialized structures within cells, performing distinct roles for cellular operation.
• Cell Membrane: Protects the cell and regulates what comes in and out.
• Cytoplasm: Location of metabolic processes, containing organelles.
• Mitochondria: "Powerhouse" of the cell, producing ATP via cellular respiration.
• Chloroplasts: Site of photosynthesis in plants, converting light energy to chemical energy.
• Cell Wall: Provides structure and protection in plant cells, made of cellulose.
• Ribosomes: Sites of protein synthesis, either free-floating or attached to the endoplasmic reticulum.
• Cytoskeleton: Provides structural support and aids cell movement.

Organelle Examples and Functions

• Mitochondria: Convert glucose into ATP through aerobic respiration.
• Chloroplasts: Contain chlorophyll, enabling photosynthesis by converting light energy into chemical energy.
• Ribosomes: Made of rRNA and proteins; they translate mRNA into polypeptides for protein synthesis.

Cell Specialization

• Different cell types have specific roles, leading to varying numbers and types of organelles.
• Example: Muscle cells have many mitochondria to meet energy needs for contraction.
• Neurons have extensive cytoskeletons for structure and signal transmission.
• Red blood cells lack a nucleus and organelles to maximize space for hemoglobin, increasing oxygen transport.

Atoms, Molecules, and Chemical Bonds

• Covalent Bonds: Atoms share electrons, forming strong connections.
• Hydrogen Bonds: Weaker interactions between polar molecules, important for water and DNA structure.
• Covalent bonds create stable molecules, while hydrogen bonds allow dynamic interactions in biological systems.

Polarity

• Molecules with unequal electron sharing are polar, exhibiting partial positive and negative charges.
• Water's polarity makes it an excellent solvent, enabling biochemical reactions.
• Polarity influences molecular interactions, affecting macromolecule structure and function.

Properties of Water

• Water is a universal solvent, dissolving substances vital for life.
• Cohesion: Water molecules stick to each other, enabling processes like capillary action.
• Adhesion: Water molecules stick to other substances, aiding nutrient transport.
• Water's unique properties (high specific heat, surface tension) maintain stable environments for organisms.

Biological Macromolecules

• Four major types: Carbohydrates, Proteins, Lipids, and Nucleic Acids.
• Carbohydrates: Composed of monosaccharides, providing energy & structural support (e.g., glucose, starch).
• Proteins: Made of amino acids; perform diverse functions (catalysis, transport).
• Lipids: Fats, oils, phospholipids; important for energy storage and cell membranes.
• Nucleic Acids: DNA and RNA; store and transmit genetic information.

Cell Membranes

• Primarily a phospholipid bilayer with hydrophilic heads facing outward, hydrophobic tails inward.
• Creates a semi-permeable barrier, allowing selective substance passage.
• Proteins embedded in the bilayer facilitate transport and communication.

Selective Permeability

• Cell membranes control the internal environment.
• Small nonpolar molecules easily pass; ions and larger polar molecules need specific transport mechanisms.
• Critical for maintaining homeostasis.

Diffusion and Osmosis

• Diffusion: Molecule movement from high to low concentration, driven by gradients.
• Osmosis: Water movement across a selectively permeable membrane, a specific type of diffusion.

Sizes and Scale

• Atoms are the smallest, followed by molecules, organelles, prokaryotic cells, and eukaryotic cells.
• Typical sizes: atoms (~0.1 nm), molecules (~1 nm), organelles (~1-10 µm), prokaryotic cells (~0.1-5 µm), eukaryotic cells (~10-100 µm).

Calculating Cellular Size

• Size of object = (Field of View diameter) / (Number of cells).