Basic Biology - Cell Theory, Structure, and Plant/Human Cell Components (GenBio, Grade 11)

A set of vocabulary-style flashcards covering key terms and concepts from the lecture notes on cell theory, cell structure, organelles, and plant vs. animal cells.

Cell Theory

The idea that all living organisms are made of cells, the cell is the basic unit of life, and all cells come from pre-existing cells.

Cell

The basic unit of life and the structural/functional unit of organisms.

Microscope

An optical instrument used to view very small objects; early compound microscopes magnified up to about 20–30x, later models up to 200x by Leeuwenhoek.

Homeostasis

Self-regulating process by which biological systems maintain stability and optimal conditions.

Chemical Energy

Energy stored in chemical bonds of food molecules; cells convert it into a usable form.

Responsiveness

Ability of a cell to detect changes and respond to maintain internal conditions.

Protection and Support

Cellular protection against pathogens and structural support for the organism.

Zacharias Janssen

Inventor of the first primitive (early compound) microscope around 1600.

Anton van Leeuwenhoek

Dutch scientist who used simple, hand-ground lenses to observe microorganisms; magnified up to ~200x.

Robert Hooke

First to describe and name the cell after observing cork under a microscope.

Matthias Schleiden

Proposed that all plants are composed of cells.

Theodor Schwann

Proposed that all animals are composed of cells.

Rudolf Virchow

Proposed that all cells arise from pre-existing cells.

Francesco Redi

Disproved spontaneous generation, supporting cell theory.

Three Principles of Cell Theory

1) All living things are made of cells; 2) The cell is the basic unit of life; 3) Cells come from pre-existing cells.

Cell Wall

Rigid external layer that protects the cell, provides structural support, and gives shape.

Cholesterol

Sterol that helps maintain cell membrane stability and fluidity.

Permeable

Describes a substance that can pass through a membrane.

Impermeable

Describes a substance that cannot pass through a membrane.

Plasma Membrane

The cell’s outer boundary; composed of phospholipids, cholesterol, membrane proteins, glycolipids, and glycoproteins; described by the fluid mosaic model.

Phospholipid

Molecule with a hydrophilic phosphate head and hydrophobic fatty acid tails that form the bilayer.

Phospholipid Bilayer

Double layer of phospholipids forming the cell membrane; head faces cytoplasm and exterior, tails face inward.

Kinks (in phospholipids)

Molecular bends that prevent tight packing and help maintain membrane fluidity.

Channel Proteins

Proteins that provide passageways for specific molecules across the membrane.

Carrier Proteins

Proteins that change shape to transport substances across the membrane.

Receptor Proteins

Proteins that bind signaling molecules to trigger cellular responses.

Glycolipids

Carbohydrates attached to lipids on the cell membrane.

Glycoproteins

Carbohydrates attached to proteins on the cell membrane.

Fluid Mosaic Model

Model describing the membrane as a mosaic of phospholipids, cholesterol, proteins, and carbohydrates that is fluid.

Membrane Fluidity

Flexibility of the membrane, influenced by cholesterol and temperature.

Selective Permeability

Membrane property that allows some substances to pass while blocking others.

Cytoskeleton

Network of protein filaments that gives the cell its shape and structural support.

Microtubules

Hollow tubes of tubulin radiating from centrosomes that form spindle fibers for chromosome movement.

Microfilaments

Thin filaments that support movement and shape changes of the cell.

Intermediate Filaments

Filaments that help maintain cell shape and anchor the nucleus.

Cytosol

Semifluid substance inside the cell that contains organelles.

Protoplasm

Living content of the cell (cytoplasm and nucleus).

Nucleus

Membrane-bound organelle that houses DNA.

Nucleolus

Region within the nucleus where ribosomal subunits begin to assemble.

Chromatin

DNA-protein complex that forms chromosomes during cell division.

Nucleoplasm

Semifluid matrix inside the nucleus.

Nuclear Envelope

Double membrane surrounding the nucleus that separates it from the cytoplasm.

Endomembrane System

Interconnected membranes including the rough/smooth ER, Golgi, lysosomes, endosomes, and vacuoles.

Rough Endoplasmic Reticulum (RER)

ER with ribosomes that synthesizes proteins.

Smooth Endoplasmic Reticulum (SER)

ER lacking ribosomes that synthesizes lipids.

Golgi Apparatus

Processing, packaging, and shipping center for proteins and lipids from the ER.

Lysosomes

Organelle containing enzymes that digest food particles and damaged organelles.

Peroxisomes

Organelles containing enzymes that break down lipids and detoxify substances.

Vacuole

Storage organelle for water, nutrients, and other substances; large in plants.

Mitochondrion

Powerhouse of the cell; generates ATP through cellular respiration.

Chloroplast

Plant/algae organelle that conducts photosynthesis; contains chlorophyll.

Grana

Stacks of thylakoids within chloroplasts where light-dependent reactions occur.

Xylem

Plant tissue that transports water and minerals from roots to all other parts.

Phloem

Plant tissue that transports sugars and other organic nutrients throughout the plant.

RBCs (Red Blood Cells)

Were biconcave; lack nucleus and mitochondria; contain hemoglobin for oxygen transport.

WBCs (White Blood Cells)

Immune cells; can be granulocytes or agranulocytes.

Egg Cells

Female gametes; largest cells in the human body; required for fertilization.

Sperm Cells

Male gametes; fertilize the egg.

Desmosomes

Junctions that connect adjacent cells providing structural cohesion.

Tight Junctions

Junctions that seal spaces between cells to prevent leakage.

Gap Junctions

Channels that allow ions and small molecules to pass between adjacent cells.

Basal Infoldings

Basal plasma membrane infoldings that increase surface area for transport.

Hemidesmosomes

Attach epithelial cells to the basement membrane, providing structural stability.

Cilia

Hair-like projections that move mucus and debris in the respiratory tract.

Stereocilia

Mechanosensory projections; in some cells (e.g., frog inner ear) detect sound.

Flagella

Tail-like structures that propel cells and enable movement.

Trichomes

Epidermal outgrowths of plants; include root hairs involved in water absorption.

Root Hairs

Tiny extensions of epidermal cells that absorb water and minerals from the soil.

Mesophyll Cells

Interior leaf tissue responsible for photosynthesis; located between epidermal layers.

Xylem and Phloem (Plant Transport Systems)

Xylem transports water/minerals; Phloem transports sugars/nominal nutrients.

Plant Cell Wall Composition by Kingdom

Bacteria: peptidoglycan; Fungi: chitin; Plants: cellulose.

Sterols in Membranes

Cholesterol in animals, phytosterol in plants, ergosterol in fungi.

Endosymbiotic Theory

Idea that eukaryotic organelles (mitochondria, chloroplasts) originated as ingested microbes living inside a host cell.

Prokaryotes vs Eukaryotes

Prokaryotes lack a nucleus and internal compartments; Eukaryotes have a nucleus and organelles.

Mesophyll

Leaf tissue where photosynthesis mainly occurs; part of the internal ground tissue.