Cell Structure Flashcards
Specialized structures in cells that perform specific functions
Organelles
Examples of Organelles
Nucleus
Mitochondria
Ribosomes
Jelly-like substance that holds organelles
Cytoplasm
A structure that encloses the cytoplasm
Cell membrane / plasma membrane
Functions of the Cell
Smallest units of life Cell metabolism and energy use Synthesis of molecules Communication Reproduction and inheritance
The outermost component of a cell.
Cell membrane / plasma membrane
It forms a boundary between material inside the cell and the outside.
Cell membrane / plasma membrane
It acts as a selective barrier.
Cell membrane / plasma membrane
Materials inside the cell are
Intracellular
Materials outside the cell are
Extracellular
Model used to describe the cell membrane structure.
Fluid-mosaic model
What does the cell membrane contains
Phospholipids
Cholesterol
Proteins
Carbohydrates.
Form a bilayer.
Phospholipids
Phospholipids contain 2 regions
Polar and Nonpolar
A phospholipid molecule has a polar head region that is
Hydrophilic
This region is exposed to water around the membrane.
Polar Region
This region is facing the interior of the membrane.
Nonpolar Region
A phospholipid molecule has a nonpolar tail region that is
Hydrophobic
Polar head region contains
Phosphate
Nonpolar tail region contains
Fatty acids
Cell membrane is made up of 2 major types of molecules
Phospholipids and Proteins
Add strength and stability by limiting movement of phospholipids
Cholesterol
What are the proteins that float among the phospholipids or extend from inner to outer surface of the membrane
Membrane channels Carrier molecules Receptor molecules Enzymes Structural supports
The cell membrane has ___________, which allows only certain substances to pass in and out of the cell.
Selective permeability
Substances such as these are found in higher concentrations inside the cell.
Enzymes, glycogen, and potassium
Substances such as these are found in higher concentrations outside the cell.
Sodium, calcium, and chloride
Some substances, like ____________ can pass directly through the cell membrane’s phospholipid bilayer.
O2 and CO2
Some substances must pass through transmembrane protein channels, such as ____ through its channels.
Na+
True or False
The route of transport through the membrane depends on the size, shape, and charge of the substance.
True
Some substances require carrier molecules to transport them across the cell membrane, such as _______.
Glucose
True or False
All substances require a vesicular transport across the membrane.
False
Some, just some
True or False
The vesicle must fuse with the cell membrane for transport.
True
This transport does not require the cell to expend energy.
Passive membrane transport
This transport require the cell to expend energy, usually in the form of ATP.
Active membrane transport
Passive membrane transport mechanisms include _____________________________.
Diffusion, osmosis, and facilitated diffusion
Active membrane transport mechanisms include _____________________________.
Active transport, secondary active transport, endocytosis, and exocytosis
Generally involves movement of substances in a solution down a concentration gradient.
Diffusion
A solution is generally composed of two major parts, ______________.
Solutes and solvent
________ are substances dissolved in a predominant liquid or gas, which is called the solvent.
Solutes
Solutes are substances dissolved in a predominant liquid or gas, which is called the __________.
Solvent
True or False
Solutes, such as ions or molecules, tend to move from an area of higher concentration of a solute to an area of lower concentration of that same solute in solution.
True
This movement from high concentration to a low concentration is _____________.
Diffusion
A ________________ is the difference in the concentration of a solute in a solvent between two points divided by the distance between the two points.
Concentration gradient
True or False
The concentration gradient is said to be steeper when the concentration difference is large and/or the distance is bigger.
False
CG is steeper when
- Concentration difference is large
- Distance is smaller
_____________ can diffuse directly through the phospholipid bilayer.
Lipid soluble substances
________________, such as ions, can diffuse across the cell membrane only by passing through cell membrane channels.
Water-soluble substances
Two classes of cell membrane channels
Leak channels and gated channels.
Constantly allow ions to pass through.
Leak channels
Limit the movement of ions across the membrane by opening and closing.
Gated channels
Is the diffusion of water (a solvent) across a selectively permeable membrane from a region of higher water concentration to one of lower water concentration.
Osmosis
The force required to prevent movement of water across cell membrane
Osmotic pressure
True or False
Osmotic pressure depends on the difference of solution concentrations inside a cell relative to outside the cell.
True
A cell may be placed in solutions that are either _______________________ compared to the cell cytoplasm.
Hypotonic, isotonic, or hypertonic
A ________ solution has a lower concentration of solutes and a higher concentration of water relative to the cytoplasm of the cell.
Hypotonic
The solution has less tone, or osmotic pressure, than the cell.
Hypotonic
Water moves by osmosis into the cell, causing it to swell.
Hypotonic
If the cell swells enough, it can rupture, a process called _______.
Lysis
A cell immersed in an _______ solution has the same solute concentrations inside and outside the cell.
Isotonic
The cell will neither shrink nor swell.
Isotonic
The cytoplasm of a cell in a ________ solution has a lower solute concentration and higher water concentration than the surrounding solution.
Hypertonic
Water moves by osmosis from the cell into the hypertonic solution resulting in cell shrinkage.
Hypertonic
Cell shrinkage
Crenation
True or False
Some water-soluble, electrically charged or large sized particles cannot enter or leave through the cell membrane by diffusion.
True
True or False
Substances such as amino acids, glucose, and some polar molecules produced by the cell are lipid-soluble
False
Water soluble
Proteins within the cell membrane involved in carrier-mediated transport.
Carrier molecules
Carrier-mediated transport mechanisms include
Facilitated diffusion and Active transport
Carrier-mediated transport that does not require ATP for energy.
Facilitated diffusion
Carrier-mediated transport that require ATP for transport.
Active transport
Is a carrier-mediated transport process that moves substances across the cell membrane from an area of higher concentration to an area of lower concentration of that substance.
Facilitated diffusion
True or False
Because active transport’s movement is with the concentration gradient, metabolic energy in the form of ATP is not required.
False
Facilitated diffusion
Is a carrier-mediated process, requiring ATP, that moves substances across the cell membrane from regions of lower concentration to those of higher concentration against a concentration gradient.
Active transport
Moves Na+ out of cells and K+ into cells.
The result is a higher concentration of Na+ outside cells and a higher concentration of K+ inside cells.
Sodium-potassium pump
Uses the energy provided by a concentration gradient established by the active transport of one substance, such as Na+ to transport other substances.
Secondary active transport
The diffusing substance moves in the same direction as the initial active transported substance.
Cotransport
The diffusing substance moves in a direction opposite to that of the initial active transported substance.
Countertransport
Is a process that brings materials into cell using vesicles.
Endocytosis
Occurs when a specific substance binds to the receptor molecule and is transported into the cell.
Receptor-mediated endocytosis
