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Emergent Properties
Emergent properties refer to the idea that the cell as a whole exhibits properties and functions that are not present in its individual organelles alone. When all the organelles are combined inside a cell membrane, life can emerge.
Cytology
The study of cells. A cytologist is a person who works with cells.
Prokaryotic Cells
Organisms that evolved before the evolution of the nuclear membrane and nucleus. They lack membrane-bound organelles and are much smaller than eukaryotic cells. Contains one circular chromosome.
Eukaryotic Cells
Evolved after the evolution of the nucleus. They have a membrane-bound nucleus and membrane-bound organelles. All organisms on Earth, except for eubacteria and archaea, are composed of thesecells.
Endosymbiotic Hypothesis
This hypothesis proposes that some prokaryotes began to live together in symbiotic relationships with smaller prokaryotes living inside larger ones. Over time, these symbionts evolved into eukaryotic cells. This hypothesis is supported by evidence found in the individual DNA of mitochondria and chloroplasts.
Surface Area-to-Volume Ratio
The surface area-to-volume ratio is an important concept for all cells. As cells grow larger, their surface area-to-volume ratio decreases, making it harder for materials to be transported in and out of the cell. Smaller cells have a higher surface area-to-volume ratio and are better able to transport materials through the cell membrane.
Selectively Permeable Membrane
The cell membrane is selectively permeable, meaning it allows certain materials to enter or exit the cell while preventing others from doing so. Small and nonpolar substances can easily enter the cell, while large and/or polar/charged substances require protein channels for transport.
Phospholipid Bilayer
The cell membrane is primarily composed of this. Phospholipids are amphipathic molecules with hydrophilic heads and hydrophobic tails. The hydrophilic heads face the water inside and outside the cell, while the hydrophobic tails face each other in the center of the membrane.
Integral Proteins
Embedded in the phospholipid bilayer and run completely through the membrane. They function in the transport of molecules across the membrane and help maintain the integrity of the membrane.
Peripheral Proteins
Located on one side of the membrane and do not extend through the bilayer. They can act as receptors, catalysts/enzymes, and structural components of the cytoskeleton.
Cholesterol
A lipid molecule that helps regulate the fluidity and permeability of the cell membrane. It also helps secure the embedded proteins and prevents freezing or over heating of cell membranes in very cold or hot temperatures. Keeps the cell’s membrane in a sort of homeostasis.
Fluid Mosaic Model
The fluid mosaic model is the current scientific model of the cell membrane. It describes the membrane as a fluid structure composed of phospholipids and embedded proteins that can move laterally within the membrane.
Eukaryotic Cell Components
These include the plasma membrane, nucleus, cytoplasm, and membrane-bound organelles. The plasma membrane regulates the substances entering and exiting the cell, the nucleus controls cell activities and holds DNA, the cytoplasm contains the organelles, and the membrane-bound organelles carry out specific functions within the cell.
Nucleus
This controls the activities of a cell because it contains the DNA which acts as the instruction for building the cell’s proteins and determining its traits.
Cytoplasm or cytosol
This fluid-filled space contains the organelles and makes up most of the volume of the cell.
Organelles
These structures specialize to carry specific functions within the cell. By specializing, they divide up the labor and make the cell more efficient. It is important to note that the number and distribution of organelles differs from cell type to cell type.
Nuclear Envelope
It is composed mainly of a double phospholipid bi-layer. It encloses the DNA. It also contains pores (tunnels) composed from proteins which allow certain specific materials to enter/exit the nucleus.
DNA
Chromatin phase—During most of the cell’s life cycle, the DNA is loose and spread-out throughout the nucleus. During the chromatin phase, the DNA looks like a bowl of plain spaghetti noodles. During the phase, the DNA can be transcribed and used to make proteins. Working form of DNA. Chromosome phase—During this phase, the DNA coils around proteins called histones (in eukaryotes and archae). The coiling helps to organize the DNA so that it can be correctly distributed during the processes of nuclear and cell division.
Nucleolus
This structure appears as a dark spot within the nucleus. The nucleolus functions to make the ribosomal RNA (rRNA) and proteins which make up the cell’s ribosomes.
Ribosomes
These are CELL PARTICLES made of ribosomal RNA (rRNA) and proteins. Ribosomes are not usually considered to be organelles because they are not enclosed within a membrane. All cell types, both prokaryotic and eukaryotic, have these. They are the sites of Protein Synthesis. The cell’s normal proteins and enzymes are ALL made here. Two types of them exist based on location: Free Ribosomes– These float “freely” in the cytoplasm of a cell. Bound Ribosomes – These ribosomes are attached to the rough endoplasmic reticulum (RER).
Endomembrane system
The endomembrane system (endo = “within”) is a group of membranes and organelles in eukaryotic cells that work together to modify, package, and transport lipids and proteins.
Endoplasmic Reticulum (ER)
It is composed of a network of small tubes called cisternae. The ER is ALWAYS found just outside and around the nucleus. Two types of ER can exist inside eukaryotic cells: Smooth Endoplasmic Reticulum (SER) and Rough Endoplasmic Reticulum (RER).
Golgi Apparatus
Also known as the Golgi Body modifies proteins by attaching sugars to them. May act as a warehouse for the storage of proteins, but eventually packages the proteins and ships them out in vesicles. The Golgi apparatus is usually located near the cell membrane.
Lysosomes
These organelles contain powerful hydrolytic enzymes and acids. They help to carry out the process of intracellular digestion. This process helps to break down materials within a cell. Once broken down, the components of some of these materials may be recycled for other purposes.
Vacuoles and Vesicles
These organelles act as phospholipid-based storage containers for the storage of materials needed by the cell. Various types such as Food, Contractile, Transport, Secretory and Central exist in different types of cells.
Mitochondria
ARE NOT THE POWERHOUSE OF THE CELL! It is more of an energy CONVERTER. If you EVER say this on a test or quiz I will automatically give you a ZERO for that question. (Just what my teacher said) Aerobic Respiration: They perform the process of aerobic cellular respiration. During this process, the energy from food is transferred to the bonds of ADP and P to create ATP. ATP then serves as the source of energy for most of the cell’s processes. They have their own DNA, bacteria-like ribosomes, enzymes, and can reproduce independently via binary fission.
Chloroplasts
These organelles are the sites of Photosynthesis in plants and algae. Have their own DNA, ribosomes, and enzymes. They can also reproduce independently via binary fission. The interior of a chloroplast is composed of stacks of sack-like structures known as thylakoids. The stroma is mostly a watery space in between the thylakoids and the outer membrane. The stroma serves as the site of the Calvin Cycle.
Cytoskeleton
These structures help to keep a cells structure in place.
Water Potential
A measure of the relative tendency of water to move from one area to another, taking into account both solute concentration and pressure.
Pressure Potential
The positive or negative pressure exerted on a cell, important in considering water movement in plants.
Solute Potential
The measure of the effect of solute concentration on water potential, calculated using the ionization constant, molar concentration, pressure constant, and temperature.
Total Water Potential
The sum of pressure potential and solute potential, determining the direction of water movement.
Facilitated Diffusion
A type of passive transport that requires the help of channel or transport proteins to move materials from high to low concentration.
Aquaporins
Channel proteins that facilitate the movement of water across a membrane via facilitated diffusion.
Gated-ion channels
Channel proteins that aid in the process of facilitated diffusion by moving sodium and potassium ions in and out of neurons and other cells.
Active Transport
The process of moving materials against the concentration gradient, requiring energy usually provided by ATP hydrolysis.
Electrogenic Pump/Electron Pump
An important active transport protein that moves hydrogen ions (protons) out of the cell, creating a gradient that serves as a source of energy for producing ATP.
Co-transport
A process in which two substances are simultaneously transported across a membrane by one protein, with one substance moving with the concentration gradient and providing energy for the transport of the other substance against the concentration gradient.
Exocytosis
The process of moving large materials out of a cell, often referred to as secretion.
Endocytosis
The process of moving large materials into a cell.
Phagocytosis
The process of transporting large, solid particles into a cell by surrounding them with the cell membrane and engulfing them in a vesicle.
Pinocytosis
A mode of endocytosis in which small particles suspended in extracellular fluid are brought into the cell through an invagination of the cell membrane.
Receptor-Mediated Endocytosis
An endocytic mechanism in which specific molecules are transported into the cell through a receptor-ligand interaction.
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