Bio cell notes

Cell

The smallest basic unit of life.

Cell Theory

The three main principles: 1) All living organisms are made of cells, 2) The cell is the basic unit of structure and function, 3) All cells come from pre-existing cells.

Unicellular Organisms

Organisms made of only one cell, e.g. bacteria and amoebas.

Multicellular Organisms

Organisms made of many cells, e.g. humans and trees.

Prokaryotic Cells

Cells that are smaller and simpler, do not have a nucleus and membrane-bound organelles.

Eukaryotic Cells

Larger and more complex cells that have a true nucleus and membrane-bound organelles.

Plant Cells

Eukaryotic cells with structures like cell walls and chloroplasts, involved in photosynthesis.

Animal Cells

Eukaryotic cells without cell walls or chloroplasts, containing lysosomes.

Nucleus

The control center of a eukaryotic cell which contains the DNA.

Mitochondria

The powerhouse of the cell that produces ATP through cellular respiration.

Ribosomes

The site of protein synthesis in the cell.

Endoplasmic Reticulum (ER)

A network of membranes involved in making and transporting materials; can be rough (with ribosomes) or smooth (without ribosomes).

Golgi Apparatus

Modifies, sorts, and packages proteins and lipids.

Lysosomes

Membrane-bound sacs containing digestive enzymes that break down waste materials.

Vacuoles

Storage sacs for water, nutrients, and waste; larger in plant cells.

Chloroplasts

Organelles found in plants and algae that carry out photosynthesis.

Cytoplasm

The jelly-like material inside the cell membrane that supports organelles.

Cytoskeleton

A network of protein fibers that helps maintain cell shape and organization.

Cell Membrane

Surrounds the cell and controls what enters and leaves.

Autolysis

The process where a cell breaks down through the action of its own enzymes.

Cell Differentiation

The process where unspecialized cells develop into specialized cells.

DNA

Deoxyribonucleic acid; the molecule that stores genetic information.

Chromosomes

Organized structures made of DNA and proteins that carry genetic information.

DNA Replication

The process of making a copy of DNA before cell division.

RNA

Ribonucleic acid; helps with the synthesis of proteins.

ATP

Adenosine triphosphate; the main energy-carrying molecule in cells.

Mitosis

The process by which a cell divides to produce two genetically identical daughter cells.

Meiosis

A type of cell division that reduces the chromosome number by half to produce sex cells.

Microfilaments

The thinnest fibers of the cytoskeleton that help with cell movement and shape.

Microtubules

The largest fibers of the cytoskeleton that help maintain cell structure and transport materials.

Cellulose

The carbohydrate polymer that forms the rigid cell walls of plant and most algal cells, providing shape and structural support.

Chitin

The tough, nitrogen-containing polysaccharide that makes up the cell walls of fungi, offering strength and protection.

Peptidoglycan (Murein)

A polymer consisting of sugars and amino acids that forms the cell wall of bacterial cells, providing protection and maintaining cellular integrity.

Nuclear Pores

Protein-lined openings in the nuclear envelope that regulate the transport of molecules, such as RNA and proteins, between the nucleus and cytoplasm.

Nucleolus

A dense region within the eukaryotic nucleus dedicated to synthesizing ribosomal RNA (rRNA) and assembling ribosome subunits.

Micrometer ($\mu\text{m}$) Conversions

Key metric conversions for cell biology: $1\,\text{mm} = 1{,}000\,\mu\text{m}$ and $1\,\mu\text{m} = 1{,}000\,\text{nm}$.

Cilia

Short, numerous, hair-like projections on cell surfaces composed of microtubules that beat rhythmically to move fluids and substances past the cell.

Flagella

Long, whip-like appendages made of microtubules (usually one or a few per cell) that propel cells through liquid environments, such as sperm cells.

Contractile Vacuole

A specialized organelle found in freshwater unicellular organisms that collects and expels excess water to maintain osmoregulation and prevent cellular lysis.

Thylakoids

Flattened, disc-like membrane sacs inside chloroplasts containing chlorophyll where the light-dependent reactions of photosynthesis take place.

Grana

Stacks of thylakoids within chloroplasts that maximize membrane surface area for light absorption during photosynthesis.

Stroma

The fluid-filled internal space of chloroplasts surrounding grana, containing enzymes, chloroplast DNA, and ribosomes, where the Calvin cycle occurs.

Cis Face of Golgi Apparatus

The receiving face of the Golgi apparatus that accepts transport vesicles containing newly synthesized proteins and lipids from the endoplasmic reticulum.

Trans Face of Golgi Apparatus

The shipping face of the Golgi apparatus that buds off secretory vesicles to deliver sorted and modified molecular cargo to destinations inside or outside the cell.

Endomembrane System

The coordinated internal membrane network comprising the nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vesicles, and plasma membrane that produces, modifies, and transports cellular substances.

Centrioles

Paired cylindrical organelles in animal centrosomes arranged at right angles, each formed by nine microtubule triplets, which organize the mitotic spindle during cell division.

Glycoproteins

Membrane proteins with attached carbohydrate chains extending into the extracellular space that function in cellular recognition, signaling, and immune identification.

Root Hair Cells

Specialized plant root epidermal cells featuring long, thin extensions that significantly increase surface area for the uptake of water and mineral ions.

Palisade Cells

Elongated plant leaf cells densely packed with chloroplasts positioned near the upper leaf surface to carry out the majority of photosynthesis.

Xylem Vessel Elements

Hollow, non-living plant vascular cells reinforced with lignin that conduct water and dissolved minerals upward from roots to shoots.

Phloem Sieve Tube Elements

Living, tubular plant vascular cells that work alongside companion cells to transport dissolved organic nutrients and sugars throughout the plant.

Guard Cells

Specialized epidermal cells flanking stomata on plant leaves that change shape to open and close pores, balancing gas exchange and transpiration.

Endosymbiotic Theory

The scientific theory stating that mitochondria and chloroplasts originated as free-living prokaryotes that were engulfed by ancestral eukaryotic host cells and established mutualistic symbioses.

Robert Hooke

The English scientist who first observed microscopic compartments in cork tissue in $1665$ and introduced the term 'cell' to biology.

Walther Flemming

The German biologist recognized for providing the first systematic, detailed descriptions of mitosis and chromosome separation during eukaryotic cell division.

Levels of Biological Organization

The hierarchical structural arrangement of living matter: Cell $\rightarrow$ Tissue $\rightarrow$ Organ $\rightarrow$ Organ System $\rightarrow$ Organism.

MRS GREN

A mnemonic representing the seven fundamental life processes shared by living organisms: Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, and Nutrition.