Homeostasis
Relative stability of the internal environment and the mechanisms that maintain the stability of it
Feedback loops
Evolved to help maintain homeostasis in organisms. The output of a system is used as a signal so that the input is changed. Can be positive or negative.
Effector
An organ that does the response in a feedback loop
Receptor
Sensory organ that receives the stimulus in a feedback loop
Stimulus
An action that evokes a response
Response
Effect caused by a stimulus
Cell theory
1- cells are the basic unit of all living things 2- all living things are made up of one or more cells 3 - cells come from preexisting cells
Positive feedback loop
Occurs in nature when the product of a reaction leads to an increase in that reaction. Response ENHANCES the initial stimulus. Ex: child birth
Eukaryotic cells
Contains a nucleus, contains organelle, DNA found in nucleus. Ex: animal cells, plant cells, fungi, protists
Prokaryotic Cells
Single-celled, no nucleus, no organelles, DNA found in the central part of cell. Ex: Bacteria, archaea
Phosoplipid
Main component of cell membranes - made up of two fatty acids, a phosphate group, and a glycerol molecule. Hydrophilic head and hydrophobic tails
Negative Feedback Loop
balancing feedback, response reverses the original stimulus. Ex: Thyroid hormone
Nucleus
Directs the cells activities, houses DNA
Cytoplasm
Liquid that fills the inside of cells, contains organelles,
Rough ER
protein synthesis (production, folding, quality, control, dispatch of proteins)
Smooth ER
lipid synthesis, detox
Ribosomes
makes proteins
Golgi Apparatus
Protein modification, sorting and packaging of protiens
Vesicles
Used to ship materials to other parts of the cell.
Lysosomes
Breaks down things in the cell (ex: sugar, protein, etc.)
Mitochondria
Powerhouse of the cell - produces energy for the cell
Cell Membrane
Regulates transport of materials entering and exiting the cell
Vacuole
Storage - in plants it is larger and mainly stores water.
Cytoskeletons
helps maintain cell shape and internal organization
Passive Transport
requires NO EXTRA energy by the cell because molecules move from high concentration to low concentration areas DOWN the concentration gradient
Active Transport
Requires EXTRA energy (in the form of ATP) to be spent to bring materials into the cell or expel materials out of the cell moving from low concentration to high concentration AGAINST the concentration gradient. Pumps molecules across membrane through a protein channel.
Concentration
number of molecules of a substance in a given volume
Concentration gradient
Difference in concentration of a substance from one location to another.
Diffusion
The spreading out of molecules across a membrane until they are equally concentrated on both sides of the membrane. High concentration to low concentration.
Facilitated diffusion
A transport protein acts as a protein channel to help facilitate the diffusion of the molecules that normally couldn't pass through the membrane
Osmosis
Diffusion of water across the cell membrane. Moves down the concentration gradient - from high to low concentration. Evens out solute concentration until an isotonic solution is achieved
Hypertonic solution
Water concentration is less outside of the cell, so this means solute concentration is greater outside of the cell. Less solute in the cell (higher water concentration). Water moves out of cell and cell shrivels
Hypotonic solutions
Water concentration is greater outside of the cell, so this means there is less solute outside the cell. More solute inside of the cell (lower water concentration in cell). Water moves into the cell and the cell swells
Isotonic solution
Identical water concentrations to what is found in a cell's cytoplasm. Cell stays the same.
Endocytosis
A cell uses energy to import large amounts of materials INTO the cell using a vesicle
Exocytosis
A cell uses energy to export large amounts of materials OUT OF the cell using a vesicle.
Transport protein
Moves materials within an organism. Allows for selective passage of specific molecules from the external environment
Integral protien
Resides within the bilayer membranes that surround cells and organelles, playing critical roles in movement of molecules across the membrane and the transduction of energy and signals. Locks itself into the membrane.
Peripheral protien
Forms temporary bonds with the cell membrane, allowing them to detach and reattach at specific times, with specific signals. Acts on the lipid-water interface, in contrast to transmembrane proteins, which are fully embedded in the cell membrane.
Cholesterol
Increases the order of the lipid packing, lowers the membrane permeability (provides stability), and maintains membrane fluidity by forming liquid-ordered–phase lipid rafts.
Glycoprotien
Enables cells to recognize another cell as familiar or foreign, which is called cell-cell recognition. Also helps cells attach to and bind other cells.
Receptor Protein
Transmit information to the cell by sensing the presence or absence of a stimulus. Facilitate communication between the cell and the external environment
Protien pump
Moves ions and/or solutes across biological membranes against a concentration or electrochemical gradient.
Sodium potassium pump
Transports sodium and potassium ions across the cell membrane in a ratio of 3 sodium ions out for every 2 potassium ions brought in. Pumps against concentration gradient.