Unit 2 notes Bio honors

Cell

The smallest unit of structure and function in living systems

Robert Hooke

The first scientist to observe and name cells (1665)

Anton van Leeuwenhoek

The first scientist to use a simple microscope to observe bacteria and Protozoa (1676)

Cell Theory (Point 1)

All living things are made of cells

Cell Theory (Point 2)

Cells are the basic units of structure and function in living things

Cell Theory (Point 3)

New cells are produced from existing cells

Cytoplasm

Gel-like substance that houses cellular structures/organelles

Cell Membrane (Plasma Membrane)

A semi-permeable membrane that protects the cell, it allows certain substances in and out of the cell,

Ribosomes

RNA enzymes that assemble proteins, NOT a membrane bound organelle,

Genetic Material

DNA, which directs cell activity and is used for reproduction,

Prokaryotic Cells

Lack a Nucleus and Membrane Bound Organelles (MBOs), DNA is in a region called the nucleoid, generally smaller and simpler

Eukaryotic Cells

Have a true nucleus and membrane bound organelles, generally larger and much more complex

Endosymbiotic Theory

Theory to determine how eukaryotic organisms arose, suggests a large ancient prokaryote engulfed a smaller prokaryote and lived in a symbiotic relationship

Endosymbiotic Theory Evidence

Mitochondria and Chloroplasts both have inner and outer membranes, possess their own DNA and Ribosomes, and divide independently of the cell, similar to bacteria

Unicellular Organism

Composed of a single cell, generally reproduce quickly and efficiently

Multicellular Organism

Composed of millions/trillions of cells, have many specialized cells that perform specific functions

Colonial Organism

Composed of physically connected interdependent individuals that can function alone or as a unit, examples include Slime molds, Volvox, and Bees

Homeostasis

The state of steady internal, physical, and chemical conditions maintained by living systems, a balance maintained through self-regulating adjustments,

Positive Feedback Mechanism

Amplifies or increases changes to a system, input causes an increase in output, which triggers a further increase in input (Examples: Pepsin production, Oxytocin in labor, Ethylene in fruit ripening),

Negative Feedback Mechanism

Dampens or decreases ("turn off") changes to a system, input causes an increase in output, which triggers a decrease in input (Examples: Thermoregulation, pH regulation, Photoregulation),

Fluid-Mosaic Model

Describes the cell membrane as a 2-DIMENSIONAL LIQUID that is constantly shifting,,

Phospholipid Bilayer

Forms the bilayer structure of the cell membrane, acting as a selective barrier, with hydrophilic heads facing outward and hydrophobic tails inward

Cholesterol

Helps maintain the fluidity and stability of the cell membrane by preventing the fatty acid chains of the phospholipids from sticking together, especially in temperature changes

Integral Protein (Intrinsic Protein)

Embedded across the membrane, involved in transporting molecules in and out of the cell or acting as receptors for signaling,

Peripheral Protein (Extrinsic Protein)

Located on the surface of the membrane, assist in cell structure by interacting with the cytoskeleton or participate in cell signaling,

Glycolipid

Involved in cell recognition and communication by interacting with molecules outside the cell, playing a key role in immune response and tissue formation,

Glycoprotein

Involved in cell signaling and recognition, where the carbohydrate portion interacts with other cells and molecules, especially in immune response,

Carbohydrate Chain/Branch

Attached to lipids or proteins, acts as markers for cell-to-cell communication and help in the identification of the cell by other cells,

Nucleus

The control center of the cell, contains nearly all of the cell’s DNA

Nuclear Membrane (Envelope)

A double membrane that is dotted with thousands of pores, allowing materials to move into and out of the nucleus

Nucleolus

Manufactures ribosomes

Endoplasmic Reticulum (ER)

An extensive internal membrane system that accounts for more than half the total membrane in a cell

Rough E.R.

Has ribosomes attached, involved in the synthesis and movement of proteins,

Smooth E.R.

Has no ribosomes attached, function is to synthesize lipids

Golgi Apparatus

Appears as a stack of loosely connected membranes, function is to modify, sort, package, and ship substances that have arrived from the endoplasmic reticulum

Lysosomes

Contain hydrolytic enzymes, function in the digestion of carbohydrates, proteins, and lipids, recycling organic materials, and destroying old organelles, plant cells do not have lysosomes,

Mitochondria

The “Powerhouse” of the cell, purpose is cellular respiration, converting glucose or sugar molecules into a usable form of energy (ATP)

Cristae

Folds on the inner membrane of the mitochondria, they increase the surface area for respiration

Vesicles

A storage area inside a cell for water, salts, proteins, and carbohydrates

Dynein

A motor protein that moves vesicles along microtubules

Peroxisome

A modified vesicle that gets rid of free radicals in the body, they produce hydrogen peroxide and contain catalase to break it down

Cytoskeleton

Internal framework and support system found in plant and animal cells, maintains shape, facilitates cell movement, and aids in intracellular transport

Microtubules

Rigid cytoskeletal structures made of Tubulin protein, function in intracellular transport, cell movement, and cell division,

Microfilaments

Flexible cytoskeletal structures made of Actin protein, function to maintain shape and provide cellular support (scaffolding beneath cell membrane)

Intermediate Filaments

Cytoskeletal structures made of Actin and other fibrous subunits, they provide mechanical strength to hold cells together at junctions and hold organelles in place

Centrioles

Organize the cytoskeleton and help separate chromosomes during cell division

Endomembrane System

The internal membrane system of a cell (including RER, SER, Vesicles, Lysosomes, Peroxisomes, Transport Vesicles, Golgi) that transports proteins and other nutrients throughout the cell

Chloroplasts

The organelle where photosynthesis takes place, converting sun energy into chemical energy (glucose), contains thylakoids

Thylakoids

Large stacks of membranes inside the chloroplasts that contain the green pigment chlorophyll

Large Central Vacuole

A very large vacuole found in mature plant cells, creates Turgor Pressure when filled with water, providing strength and support, and stores organic compounds

Turgor Pressure

Pressure created when the large central vacuole is filled with water, giving strength and support to the cell

Cell Wall

A supporting structure found in cells of plants, fungi, and bacteria, provides support and protection, composed of cellulose and lignin in plants.

Cell Transport

The movement of materials across cell membranes

Passive Transport

DOES NOT require ATP and moves substances from an area of HIGH concentration to LOW concentration

Simple Diffusion

The passive transport of typically small, hydrophobic, or gaseous substances without the aid of membrane proteins,

Facilitated Diffusion

The passive movement of substances (like biological molecules or ions) across a plasma membrane by means of a transport protein,

Osmosis

The movement of water molecules from a solution with a high concentration of water molecules to a solution with a lower concentration of water molecules, through a partially permeable membrane

Aquaporins

Channels involved in osmosis

Hypertonic Solution

A solution that has a HIGHER solute concentration than the cell

Hypotonic Solution

A solution that has a LOWER solute concentration than the cell

Isotonic Solution

A solution that has an EQUAL solute concentration to the cell

Lysed (Animal Cell)

The result when an animal cell swells/bursts in a hypotonic solution

Turgid (Plant Cell)

The normal, firm state of a plant cell when water enters by osmosis and pushes against the cell wall,

Shriveled (Animal Cell)

The result when an animal cell loses water to a hypertonic solution

Plasmolyzed (Plant Cell)

The result when a plant cell loses water, causing the vacuole to shrink and the cell to lose shape in a hypertonic solution,

Active Transport

Requires ATP and moves substances from an area of LOW concentration to HIGH concentration

Protein Pumps

Proteins capable of pumping compounds in and out of the cell,

Symport

Substances being moved in the same direction via a protein pump

Antiport

Substances being moved in a different direction via a protein pump

Uniport

Substances moving in only one direction via a protein pump

Sodium-Potassium Pump

Crucial pump in nerve cells for sending electrical signals throughout the body

Endocytosis

The process by which cells take in substances from outside of the cell by engulfing them in a vesicle,

Phagocytosis

Cell "eating" large particles

Pinocytosis

Cell "drinking" fluids

Receptor-Mediated Endocytosis

A process through which bulk amounts of specific molecules can be imported into a cell after binding to cell surface receptors

Exocytosis

The process by which cells move materials from within the cell into the extracellular fluid,

Ligand

A small signal molecule (e.g., Neurotransmitter, Hormone) that binds to receptors to transmit signals within or between cells

Receptor

Proteins that bind to ligands that initiate signal transduction

Signal Transduction

The transmission of a signal along a communication pathway

includes all cellular processes that come after ligand binding,

Response

The final cellular action in a signaling pathway, such as lowered blood sugar in the Insulin pathway

Tight Junction

Seals neighboring cells together and prevents leakage (Common in Stomach Lining)

Gap Junction

Allows passage of small water-soluble ions (Common in Cardiac Muscle, Nerves)

Desmosome

Joins intermediate filaments in one cell to those of a neighboring cell (Common in Skin, Muscle),

Hemidesmosome

Anchors intermediate filaments in a cell to the base (Common in Skin)

Plasmodesmata

Membranous channels that cross walls of adjacent plant cells, linking the cytoplasm, plasma membranes and ER, allowing cell-to-cell communication

Cell Size Limitation Solution (Divide)

A way cells cope with a decreasing surface area to volume ratio (SA:Vol)

Cell Size Limitation Solution (Metabolism)

Cells slow metabolism to lower energy needs and produce less waste

Cell Size Limitation Solution (Change Shape)

Cells change shape (e.g., become thin/flat or develop many folds in the cell membrane) to increase surface area