Cell Theory and Cellular Biology Overview (Video Notes)

Cell Theory

Fundamental concept that cells are the basic units of structure and function in all organisms.

Postulates of Cell Theory

1) All living things are made up of cells; 2) The cell is the basic unit of structure and function in living things; 3) All cells come from pre-existing cells.

All living things are made up of cells

Living things are composed of cells, the building blocks of life.

The cell is the basic unit of structure and function

Cells are the fundamental units that determine the structure and function of organisms.

All cells come from pre-existing cells

New cells arise from existing cells through cell division.

Reproduction (characteristic of life)

Living things can produce offspring, increasing population and diversity.

Regulation (homeostasis)

Living things maintain internal balance (e.g., temperature, water) to stay stable.

Adaptation

Populations slowly change to survive better; genetic changes are passed generations.

Energy processing (metabolic activity)

Living things obtain and use energy from food or light to stay alive.

Response to stimulus

Organisms react to environmental changes to survive.

Growth and development

Growth means size increase; development refers to changes in abilities and structure.

Order

Organized structure from cells to organ systems in living things.

Schleiden

Concluded plant tissues are composed of cells.

Schwann

Extended Schleiden’s idea to animals; proposed all animal tissues are made of cells.

Rudolf Virchow

Proposed that all cells arise from pre-existing cells via cell division.

Robert Remak

Provided evidence for cell division and proposed ideas about binary fission.

Binary fission

Asexual reproduction where a single-celled organism divides into two identical cells.

Endosymbiotic Theory

Mitochondria and chloroplasts originated from bacteria taken in by early cells.

Mitochondria

Organelle that produces energy (ATP) via cellular respiration; has own DNA and ribosomes.

Chloroplasts

Organelle that conducts photosynthesis; contains chlorophyll and has own DNA.

Evidence for endosymbiosis (DNA, ribosomes, division)

Mitochondria/chloroplasts possess their own DNA, ribosomes, and divide by binary fission.

Mitochondrial DNA

Mitochondria’s own circular DNA separate from the nucleus.

Chloroplast DNA

Chloroplast’s own genetic material separate from the nuclear DNA.

Mitochondrial ribosomes

Ribosomes within mitochondria that synthesize some mitochondrial proteins.

ATP synthase

Enzyme that uses proton flow across the inner membrane to generate ATP.

Plasmodesmata

Channels between plant cells enabling transport and communication.

Miasma Theory

Old belief that diseases spread through “bad air” from rotting matter.

Germ Theory

Idea that microbes cause diseases, proven by Pasteur and Koch.

Miller-Urey Experiment

1953 experiment showing amino acids can form from simple gases and sparks, suggesting a pathway to life’s building blocks.

Biosphere

All parts of Earth where life exists.

Ecosystem

Living organisms in an area plus the non-living environment they interact with.

Community

All the different populations of organisms in an area.

Population

A group of the same species living in one area.

Organism

An individual living thing.

Organ System

Group of organs working together to perform a function.

Tissues

Groups of similar cells performing a specific function.

Cells

The basic unit of life; all living things are made of cells.

Organelles

Small structures inside cells with specific jobs (e.g., nucleus, mitochondria).

Molecules

Groups of atoms bonded together.

Atoms

The smallest units of matter; building blocks of everything.

Emergent Properties

New features that arise when parts interact in a system (e.g., heart beating from many cells).

Systems Biology

Study of how all parts of a living system work together.

Reductionism

Approach focusing on small parts to understand the whole.

Abiogenesis

Idea that life arose from non-living matter in early Earth.

Plant Cell Components: Cell Wall

Rigid outer layer made of cellulose that provides support and protection.

Plant Cell Components: Cell Membrane

Lipid bilayer that controls entry/exit of substances.

Nucleus

Large organelle with DNA; controls cell activities.

Nucleolus

Region inside the nucleus that produces ribosomes.

Cytoplasm

Jelly-like fluid where organelles reside and reactions occur.

Cytosol

Fluid portion of cytoplasm, excluding organelles; site of many reactions.

Ribosomes

RNA-protein complexes that synthesize proteins.

Rough Endoplasmic Reticulum (Rough ER)

ER with ribosomes; synthesizes and transports proteins.

Smooth Endoplasmic Reticulum (Smooth ER)

ER without ribosomes; synthesizes lipids, stores Ca2+, detoxifies.

Golgi Apparatus

Modifies, sorts, and packages proteins and lipids for transport.

Mitochondria (plant cell)

Powerhouse of the cell; energy production; has cristae and own DNA.

Chloroplasts

Site of photosynthesis; contains chlorophyll, thylakoids, and stroma.

Vacuole (Central Vacuole)

Large, fluid-filled storage organelle that maintains turgor in plants.

Peroxisomes

Break down fatty acids and detoxify harmful chemicals.

Plasmodesmata

Channels between plant cells for transport and communication.

Animal Cell vs Plant Cell

Animal cells lack cell walls and large central vacuoles; plant cells have cell walls and chloroplasts.

Nucleoid

Region in prokaryotes where the DNA is located (not membrane-bound).

Plasmid

Small circular DNA molecule in bacteria carrying extra genes.

Capsule

Sticky outer coating that protects bacteria and aids adhesion.

Pili (Fimbriae)

Hair-like projections that help bacteria attach to surfaces.

Flagella

Long tail-like structure that enables movement.

Inclusion Bodies

Storage granules for nutrients within bacteria.

Prokaryotic Cell

Cells without a nucleus or membrane-bound organelles; single-celled.

Nuclear Envelope

Double membrane surrounding the nucleus with nuclear pores.

Nuclear Pores

Passageways in the nuclear envelope allowing RNA and protein transport.

Nucleoplasm

Gel-like fluid inside the nucleus.

Chromatin

DNA wrapped around proteins; condenses into chromosomes during cell division.

Chloroplast Stroma

Fluid inside chloroplast where the Calvin cycle occurs; contains enzymes, DNA, and ribosomes.

Thylakoids

Disc-shaped membranes inside chloroplasts containing chlorophyll; site of light reactions.

Grana

Stacks of thylakoids increasing surface area for light capture.

Chlorophyll

Green pigment that captures light for photosynthesis.

Chloroplast DNA

Chloroplast’s own genetic material.

Ribosomes (chloroplasts)

Ribosomes within chloroplasts that synthesize chloroplast proteins.

Prokaryotic vs Eukaryotic Cells

Prokaryotes lack nucleus and membrane-bound organelles; eukaryotes have these features and are more complex.

3 Domains of Life

Bacteria (prokaryotes), Archaea (prokaryotes), and Eukarya (eukaryotes).

Kingdom Animalia

Multicellular, cannot make their own food; typically motile; examples include humans, dogs, fish.

Kingdom Plantae

Multicellular; photosynthetic; cell walls made of cellulose; non-motile.

Kingdom Fungi

Can be unicellular or multicellular; absorb nutrients from others; cell walls of chitin.

Kingdom Protists

Mostly unicellular; diverse; some photosynthesize, some consume others.

Taproot System

One main thick primary root growing deep into the soil.

Fibrous Root System

Many thin roots spreading shallowly to stabilize and absorb nutrients.

Root Hairs

Extensions of root epidermal cells increasing water and mineral uptake.

Trichomes

Hairlike outgrowths on stems/leaves reducing water loss or providing protection.

Prop Roots

Roots that support tall plants by extending above ground.

Storage Roots

Roots that store food (e.g., carrots, beets, sweet potatoes).

Pneumatophores

Air root extensions that help gas exchange in waterlogged soils.

Strangling Aerial Roots

Roots that wrap around another plant and anchor it, aiding support.

Buttress Roots

Wide roots that stabilize large trees.

Rhizomes

Underground stems that store food and help propagation (e.g., ginger).

Bulbs

Underground storage organs formed by layered leaves (e.g., onions, tulips).

Stolons

Horizontal stems (runners) that spread and form new plants at nodes.

Tubers

Enlarged ends of rhizomes or stolons for storage (e.g., potatoes).

Tubers vs Tuber Stem

Tubers are storage organs formed from stems or stolons, while tuber stems have buds ('eyes'); storage roots store food but lack buds.

Leaves

Main site of photosynthesis; flat, broad organs growing from stems.

Tendril

Leaf or stem modification used to grasp supports.

Spines

Leaf modifications in cacti adapted for protection and water conservation.