A thin membrane around the cytoplasm of a cell. Double layer of phosolipids and embedded proteins. Forms an important barrier between the cell and it's external environment.
Prokaryotic cells lack:
internal compartmentalization, membrane-enclosed nucleus and membrane-enclosed organelles.
a type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles.
idea that all living things 1. are composed of cells, 2. cells are the basic units of structure and function in living things, and 3. new cells are produced from existing cells
If a solute crosses a membrane from a region of high solubility to region of low concentration without the aid of a transport protein, the process is called:
The movement of substances into or out of cells without the expenditure of energy or the involvement of transport proteins in the cell membrane. Also called simple diffusion.
plastid containing chlorophyll and other pigments. Utilizes light energy to synthesize glucose.
process in which extensions of cytoplasm surround and engulf large particles and take them into the cell
The region of a eukaryotic cell that is inside the plasma membrane and outside the organelles. Site of many metabolic pathways.
a thin type of protein filament composed of actin proteins that forms part of the cytoskeleton and supports the plasma membrane and plays a key role in cell strength, shape and movement
A type of hollow protein filament composed of tubulin proteins that is part of the cytoskeleton and is important for cell shape, organization, and movement.
A protein that keeps other proteins in an unfolded state during process of post-translational sorting.
A transmembrane that opens and closes in response to changes in electrical potential.
Fluid mosaic model
The currently accepted model of cell membrane structure, which envisions the membrane as a mosaic of individually inserted protein molecules drifting laterally in a fluid bilayer of phospholipids.
True or false: Due to its structure, cholesterol adds to the fluidity of biological membranes.
Which biological macromolecules is most likely to be components of a biomembrane?
Lipids, carbs and proteins.
Under what conditions would a biomembrane be the most fluid at 37°C?
Short unsaturated fatty acyl tails and no cholesterol
True or False: The movement of water across a semipermeable membrane to balance solute concentrations is called osmosis and requires energy input.
Carriers that bind two or more molecules or ions and transport them in opposite directions
Carriers that bind two or more molecules or ions and transport them in the same direction
True or False: Existing proton (H+) gradients frequently provide the energy required to move nutrients against their concentration gradients.
What are the main differences between plant and animal cells?
Plants have chloroplasts which use light to produce energy. Animal cells don't have cell walls. Plants have one large central vacuole, and animal cells have one more smaller vacuoles. Only animal cells have lysosomes and centrioles. Animal cells have a round irregular shape and plant cells have a fixed rectangular shape.
What does the smooth ER do?
Functions in diverse metabolic processes such as detoxification, carb metabolism, accumulation of calcium ions and synthesis and modification of lipids.
What does the rough ER do?
Protein sorting. Insertion of certain newly made proteins into the ER membrane. Attachment of carbs to proteins and lipids (glycosylation).
Actin filaments and microtubules that provide shape and aid in movement. Protein of the cytoskeleton also act as railroad tracks for movement of materials around the cell and allow movement of cells by flagella.
What does the cytoskeleton do for the cell?
Structure, movement (within the cell or cell movement), spindle fibers that sort and seperate chromosomes. Highway for transport.
any of various small particles in the cytoplasm of the cells of plants and some animals containing pigments or starch or oil or protein
Which organic molecules are found in membranes?
Phosphlipids (structure). Proteins (function). Carbohydrates attached to lipids or to proteins
What purposes to Cell membranes serve?
• Organize *delineate areas within the cell.
• Keep desirable components in and undesirable out.
• Semipermeable - allows things to move across it.
• Anchoring of cytoskeleton.
• Cell compartmentalization
• Cell communication/signaling.
• Production of energy intermediates.
The starting point of all plants. A common precursor of the different plastids, including the chloroplast, chromoplast, and amyloplast.
The sum of he chemical reactions by which cells produce the materials and utilize the energy that are necessary to sustain life.
What are the three parts that make up the cytoskeleton?
Microtubules, intermediate filaments and actin filaments.
A structure composed of protein and rRNA that provides the site where polypeptide synthesis occurs.
What are the two parts of phospholipids?
Water-loving (hydrophilic) heads and water-hating (hydrophobic) tails.
Phospholipids form in...
A bilayer. Because cells live in a watery enviroment, two layers of phospholipids get together and form a bilayer, with the hydrophilic heads pointing out, and the hydrophobic heads pointing in.
What are the two main types of large-proteins found in membranes? What do they do?
Receptors search the environment for signals like food molecules. Transporters help molecules cross the membrane.
Molecules that are ???? can only cross the membrane with the help of a transport protein.
What kinds of molecules can cross the membrane without a transport protein?
Really small molecules and hydrophobic molecules (Because they are attracted to the hydrophobic layers on the inside of the membrane). I.e carbon dioxide, oxygen and water.
Transport proteins that are folded so they have a channel, or tunnel, through their centers. These channels fill with water so hydrophilic molecules can pass through them and get across the membrane.
unassisted diffusion of solutes through the plasma membrane through a channel protein.
Molecule crossing through the plasma membrane with the aid of a carrier protein.
transport of a substance across a cell membrane by diffusion. From an area of high concentration to low concentration.
Transport of molecules from an area where they are less concentrated to an area where they are more concentrated. In the process, they utilize cellular energy in the form of ATP. The movement of a substance against a gradient.
a special form of active transport that occurs exclusively in prokaryotes, the substance is chemically altered during transport across the membrane.
process by which a cell takes material into the cell by infolding of the cell membrane. Part of the plasma membrane reaches out and wraps around the molecule to be taken in. Forms a sphere of the membrane called a vesicle.
Little organs. Cellular structures that have a membrane border. Like the organs in your body.
A system that makes and transports proteins and lipids. the collection of membranes inside and around a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles
Ribosomes are formed in the... then travel to the... to assist with...
Nucleolus.. cytoplasm... protein synthesis
Little spheres of membrane that travel around the cell and join with other membranes. Transports molecules created by the cell.
Which endoplasmic reticulum has ribosomes attached to it? What do these ribosomes do?
Rough. They synthesize proteins that are going to be part of membranes or that will leave the cell.
stack of membranes in the cell that modifies, sorts, and packages proteins from the endoplasmic reticulum
Integral membrane protein
A protein embedded in the lipid bilayer of a cell. These are typicallly cell surface receptors, channels, or pumps. Transmembrane proteins and lipid-anchored proteins.
A concentration gradient created by pumping ions into a space surrounded by a membrane that is impermeable to the ions.
A solute crossing a biomembrane from a region of low concentration to a region of high concentration with the aid of a transport protein and energy is most accurately referred to as
Arrange the following molecules in order from most likely to least likely to pass through a biomembrane.
2. carbon dioxide
4. K+ (Potassium ion)
2, 3, 1, 4.
A transmembrane channel that opens and closes in response to the direct binding of a molecule to the channel protein itself is referred to as a(n)
A protein pore in the plasma membrane that opens or closes in response to a chemical signal, allowing or blocking the flow of specific ions.
Synthesis of carbohydrates that are transferred to protein, is the covalent attachement of a carbohydrate to a lipid (forms glycolipid) or a protein (glycoprotein)
What are the three main types of proteins?
Transmembrane proteins, lipid-anchored proteins and peripheral membrane proteins.
What are the types of integral membrane proteins?
Transmembrane proteins and lipid-anchored proteins.
The carbohydrate synthesized in glycolysation can serve as...
a recognition marker or a protective cell coat.
In eukaryotic cells where are most membrane phospholipids synthesized?
At the cytosolic leaflet of the smooth ER membrane. Flippases move some phospholipds to the other leaflet.
Primary active transport vs. secondary active transport
Primary active transport involved pumps that directly use energy to generate a solute gradient. Secondary active transport uses a pre-existing gradient.
an electrogenic ATP-driven pump. Follows a series of steps that direct the pumping of ions across the membrane.
A form of endocytosis in which a receptor is specific for a given cargo.
What happens when signals and receptors interact?
the receptor changes shape which changes the way the receptor interacts with cellular factors
What are the five types of cell-signaling?
Direct intercellular signaling
Contact dependent signaling
Direct intercellular signaling
cells adjacent to each other have cell junctions that enable them to pass ions, signal molecules, etc between cell cytosols.
Contact dependent signaling
membrane bound signaling molecule on one cell, while other cells have receptors on their cell to respond to the signaling molecule.
cell secretes signaling molecule that binds to receptors on its own cell surface stimulating a response; important because it allows cells to experience cell density and inhibit further cell growth; high density=high autocrine signaling
specific cell secrets a signaling molecule which does not affect the secreting cell but influences the behavior of target cells in its proximity; short in duration;
occurs over long distances; involves secretion of hormones into blood stream (gases diffusing through air or vascular system in plants)
What are the three stages of cell signaling?
1. Receptor activation. 2. Signal transduction. 3. Cellular response.
signaling molecule binding to receptor causes receptor shape to change, activating its function.
signal transduction pathway affects the functions/amounts of cell proteins, producing a response.
Three common categories of proteins that are controlled by cell signaling:
enzymes, structural proteins, and transcription factors.
A ligand is most accurately defined as a
signaling molecule that binds to a cellular receptor.enzyme that phosphorylates amino acids of other proteins.
Small or large signaling molecules unable to pass through the plasma membrane must utilize ???? to gain entry.
The small molecules or ions that bind surface receptors in the plasma membrane of a cell are most accurately referred to as
enzymes that transfer a phosphate group from ATP to specific amino acids in a protein.