Biology of cells Flashcards
Plasma membrane
the outer limiting barrier that separates the internal contents of the cell from the interstitial fluid
Interstitial fluid
the fluid that surrounds the cell
What are the modified extensions of the plasma membrane?
cilia, a flagellum, and microvilli
Nucleus
the largest structure inside a cell containing DNA
What is the nucleus enclosed by?
the nucleus envelope
What is the fluid within the nucleus called?
nucleoplasm
Nucleous
dark-staining body within the nucleus
Cytoplasm
a general term for all the cellular contents located between the plasma membrane and the nucleus
What are the three primary components of cytoplasm?
cytosol, organelles, and inclusions
Cytosol
the viscous, syrup-like fluid in the cytoplasm
Organelles
complex, organized structures in the cytoplasm of a cell with unique shapes and characteristics
What are the two types of organelles?
Membrane-bound and non-membrane-bound organelles
Membrane-bound organelles
are enclosed by a membrane similar to the plasma membrane
Function of organelle membrane
separate the organelle’s content from the cytosol so that specific functions of the organelle can occur without interruption
What are examples of membrane-bound organelles?
endoplasmic reticulum, Golgi apparatus, lysosomes, and mitochondria
Non-membrane-bound organelles
are not enclosed by a membrane
What are the general functions of cells?
maintain the integrity and shape of a cell, obtain nutrients and form chemical building blocks, and dispose of waste
Plasma membrane function
regulate what moves in and out of the cell
What is the main type of lipid present in the plasma membrane?
phosopholipids
What is the main type of lipid present in the plasma membrane?
phospholipids
How do phospholipid associate in the plasma membrane?
form two parallel sheets of molecules lying tail to tail, with the hydrophobic tail forming the internal environment of the membrane and their hydrophilic polar heads positioned adjacent the cell’s cytoplasm or interstitial fluid
What is the plasma membrane framework called?
phospholipid bilayer
Where is cholesterol located in the plasma membrane?
scattered within the inner hydrophobic regions of the phospholipid bilayer
Cholesterol function in plasma membrane
strengthens and stabilizes it at extreme temperatures
Glycolipids
lipids with an attached carbohydrate
What are the two structural types of membrane proteins?
integral and peripheral
Integral proteins
proteins embedded within and completely extend across the phospholipid bilayer
Peripheral proteins
are not embedded within the lipid bilayer,
How are peripheral proteins attached to the membrane?
they are attached loosely to either the internal or external surfaces of the membrane; and are often “anchored” to the exposed parts of an integral protein
Transport proteins
regulate the movement of substance across the plasma membrane
What are the different types of transport proteins?
channels, carrier proteins, pumps, symporters, and antiporters
Cell surface receptors (receptors)
bind specific molecules called ligands
Identity markers
communicate to other cells that they belong there
Enzymes
attached to either the internal or external surface of a cell for catalyzing a chemical reaction
Anchoring sites
secure the cytoskeleton to the plasma membrane
Cytoskeleton
the internal protein support of a cell
Cell-adhesion proteins
for cell-to-cell attachements
Diffusion
the movement of either ions or molecules down their concentration gradient
Kinetic energy
the random constant motion of ions and molecules
Concentration gradient
the difference in concentration of a substance between two areas
Simple diffusion
the passive transport used when small nonpolar molecules cross the plasma membrane unassisted
Simple diffusion is only dependent on what?
the concentration gradient
Facilitated diffusion
the passive transport using carrier proteins or channel proteins to move a chemical across the plasma membrane
Facilitated diffusion
the passive transport using carrier proteins or channel proteins to move a chemical across the plasma membrane
What are the two types of facilitated diffusion?
channel-meditated-diffusion and carrier-meditated-diffusion
Channel-meditated diffusion
is the movement of small ions across the plasma membrane through water-filled protein channels
What are the two kinds of channel-meditated diffusion?
leak channel and gated channel
Leak channel
continuously open
Gated channel
usually closed and only opens in response to stimulus and stays open for a fraction of a second before closing
Carrier-meditated diffusion
assist movements of molecules by changing the shape after a specific molecule binds
Larger polar molecules require what to cross the plasma membrane?
a carrier protein
Uniporter
a carrier that transports only one substance
Osmosis
the passive movement of water through a semipermeable membrane
Aquaporin
protein channels in the plasma membrane allowing the passage of water
A solution with a greater concentration of solutes, contains a ________ concertation of _________.
lower, water
In osmosis, water continues to move until what is achieved?
equilibrium
Osmotic pressure
is the pressure exerted by the movement of water across a semipermeable membrane due to the difference in water concentration
Hydrostatic pressure
is the pressure exerted by a fluid on the inside wall of its container
Hydrostatic pressure and Osmotic pressure are what?
equal
Tonicity
the ability of a solution the change the volume or pressure (sometime called the tone) of the cell by osmosis
What are the three types of tonicities?
isotonic, hypertonic, hypotonic
Active Transport
is the movement of a solute against its concentration gradient (L to H) across cellular membrane
Ion pumps
cellular protein pumps that move ions across the membrane
What is an important type of ion pump?
sodium-potassium (Na+/K+) pump
Vesicle
a membrane-bound sac filled with materials found in the cytoplasm
Vesicular transport
allows for the movement of large substances across the plasma membrane
What are the two types of vesicular transports?
endocytosis and exocytosis
Exocytosis
large substances or large amounts of substances are secreted from/outside the cell
Endocytosis
the intake of large substances or large amounts of substances from the external environment into the cell
What are the three types of endocytosis?
Phagocytosis, pinocytosis, and receptor-mediated endocytosis
Phagocytosis
a nonspecific process that occurs when a cell engulfs or captures a large particle external to the cell forming membrane extensions pseudopia to surround the particle
What does “phago-“ mean?
eat or engulf
Pinocytosis
cellular/drinking; when multiple small regions of the plasma membrane invaginate and multiple, small vesicles are formed as the cell internalizes interstitial fluid that contains dissolved solutes
Receptor-mediated endocytosis
uses receptors on the plasma membrane to bind specific molecules within the interstitial fluid and bring the molecules into the cell
What does “pino-“ mean?
drink
What are the functions of the plasma membrane?
- protect and support
- regulate transport
- communication
The nucleus is also known as what?
the control center
What is the function of the cytoplasm?
metabolism
The cell membrane separates what?
the cytoplasm from the interstitial fluid
What organic molecules make up the plasma/cell membrane?
carbohydrates, proteins, and lipids
What are the three lipids that makeup the plasma/cell membrane?
phospholipids, cholesterol, and glycolipids
What percent of the plasma/cell membrane is phospholipids?
75%
What percent of the plasma/cell membrane is cholesterol?
20%
What percent of the plasma/cell membrane is glycolipids?
5%
What is the function of phospholipids for the plasma/cell membrane?
framework
What is the function of glycolipids for the plasma/cell membrane?
identity markers
What kind of molecules easily cross the lipid bilayer?
small nonpolar molecules
What is an example of a molecule that can easily cross the lipid bilayer?
O2
What are the different types of membrane proteins?
transport proteins, receptors, identity markers, enzymes, anchoring sites, and cell-adhesion
Vesicle =
bubble
What dies facilitated mean?
help
What are the two types of membrane transport?
passive and active
What are the types of passive diffusion?
simple diffusion, facilitated diffusion and osmosis
What are the two types of active transport?
ion pumps and vesicular transport
Gradient =
difference
What direction do molecules in simple and facilitated diffusion move in?
H to L
How are simple diffusion and facilitated diffusion different?
facilitated requires membrane proteins
What are the two membrane proteins involved in facilitated diffusion?
Channel and carrier proteins
What are the two types of gated channels?
Chemically gated and voltage gated
Chemically gated channel
requires the binding of a specific signaling chemical
Voltage gated channel
triggered by a specific change of the charges across the membrane
What kind of molecules can participate in simple diffusion?
small nonpolar molecules
What kind of molecules can use facilitated diffusion?
small polar or charged molecules
Whan does osmosis occur?
- two solution with different concentrations
- solutes cannot cross the membrane
- water moves through aquaporins until equilibrium is reached
What is the one rule of osmosis?
water always moves into the HYPERtonic solution
Hypertonic
“more solute”
Hypotonic
“less solute”
Isotonic
“equal solutes”
Hypotonic solutions lead to what?
Lysis
Lysis
burst or break of the cell membrane
Crenation
the shrinkage of a cell
Hypertonic solutions lead to what?
crenation
