L2 Flashcards
Key components of a cell include: _ cytoplasm nucleus plasma membrane endoplasmic reticulum mitochondria cytoskeleton
plasma membrane
Key components of a cell include: plasma membrane _ nucleus plasma membrane endoplasmic reticulum mitochondria cytoskeleton
cytoplasm
Key components of a cell include: plasma membrane cytoplasm _ plasma membrane endoplasmic reticulum mitochondria cytoskeleton
nucleus
Key components of a cell include: plasma membrane cytoplasm nucleus _ mitochondria cytoskeleton
endoplasmic reticulum
Key components of a cell include: plasma membrane cytoplasm nucleus endoplasmic reticulum _ cytoskeleton
mitochondria
Key components of a cell include: plasma membrane cytoplasm nucleus endoplasmic reticulum mitochondria _
cytoskeleton
The main components of the cell include:
_
cytoplasm
plasma membrane
nucleus
The main components of the cell include:
nucleus
_
plasma membrane
cytoplasm
The main components of the cell include:
nucleus
cytoplasm
_
plasma membrane
The acronym ER is the _, a component of the cell
endoplasmic reticulum (RER is rough endoplasmic reticulum, and SER is smooth…, helpful for lipid synthesis)
The three parts of the cell that are focused on in this course are the:
_
ribosome
Golgi complex
rough endoplasmic reticulum
The three parts of the cell that are focused on in this course are the:
rough endoplasmic eticulum
_
Golgi complex
ribosome
The three parts of the cell that are focused on in this course are the:
rough endoplasmic eticulum
ribosome
_
Golgi complex
This forms the cell’s outer surface:
plasma membrane
This conssits of the cellular contents between the plasma membrane and nucleus:
cytoplasm
A large organelle that houses most of the cell’s DNA is the…
nucleus
In most cases, the only activity happening in a cell occurs in the cell’s _
nucleus
Antibodies are large _
proteins
B cells are referred to as…
antibodies
A cell membrane has a _ barrier.
fluid, although sturdy
The plasma membrane has _ layers
2 (bilayer)
_% of a lipid bilayer is phospholipids
75 (you have mostly phosphate - creates the ATP!; then _, then glucose - another form of energy, at 5%)
_% of a lipid bilayer is cholesterol
20
_% of a lipid bilayer is glycolipids
5
glycolipids are liipids that attach to _ groups
carbohydrate
Cholesterol are lipids that attach to _ groups
steroids
Heads of lipids are considered hydrophilic, or have an affinity to _
water
Heads of lipids are considered _, or have an affinity to water
hydrophilic
The internal portion of the phospholipid layer is hydrophobic, or _ _
against water
The components of a cell from exterior to interior are:
_
cytoplasm
nucleus
plasma membrane
The lipid bilayer has two back-to-back layers made up of _ types of lipid molecules
three
The _ of phospholipids face _ each other
towards
Polar heads face _ other polar heads
away from (kind of like the two ends of an hourglass
Several proteins are found _ the phospholipid bilayer
within
If you have too many proteins within a phosoplipid bilayer, it will be less _
flexible
Some proteins that exist close to the surface of the phospholipid bilayer can join proteins. This is called a _ protein
peripheral
The shape of a peripheral protein, which binds the carbohydrate chain, looks like a _
corkscrew
The shape of a peripheral protein, which binds the _ chain, looks like a corkscrew
carbohydrate
_ molecules have both a polar and nonpolar region.
lipid
Polar regions are at the _ of a lipid bilayer
head
Phospholipids have _=containing heads
phosphate
The phosphate makes the head (polar) regions water-loving, or _
hydrophilic
The nonpolar parts are made of _ that looks like two tails
fatty acids
The fatty acid regions are water fearing, or _
hydrophobic
Why are the heads of the bilipid layer hydrophilic, and the tail (or interior) hydrophobic?
to ensure fluidity along each membrane that separates water from itself, but maintaining structure within its interior (i.e., oil and water do not mix)
The hydrophilic heads enable the lipid bilayer to be _
flexible
T/F: Phospholipids’ hydrophilic heads govern the mutability of the lipid bilayer
Not exactly. the inclusion of cholesterol and glucolipids also affects it’s mutability
The more cholesterol and glucolipids, the greater the _ of the lipid bilayer
rigidity
The plasma membrane consists of _ proteins: peripheral and integral
two
The plasma membrane consists of two _: peripheral and integral
proteins
The _ consists of two proteins: peripheral and integral
plasma membrane
The plasma membrane consists of two proteins: _ and integral
peripheral
The plasma membrane consists of two proteins: peripheral and _
integral
_ proteins are within in the bilipid layers
integral
Periphery proteins are found on the periphery of the _
plasma membrane
Membrane proteins are found throughout the _ bilayer
phospholipid
Periphery proteins can be on the _ or _ of the membrane
inside or outside edge
_ proteins span the width of the membrane
transmembrane
transmembrane proteins are examples of _ proteins
integral (transmission is integral!)
_ proteins hit the inside and outside of the plasma membrane
transmembrane integral
Peripheral proteins are _ attached
loosely
Many peripheral proteins are _, bound to carbohydrates
glycoproteins
Cytosol is found within the _CF
ICF, intracellular
A _ is an opening in a membrane
pore
Membrane proteins include: _ recognition p receptor p carrier p enzymes channels
anchoring
Membrane proteins include: anchoring p _ receptor p carrier p enzymes channels
recognition
Membrane proteins include: anchoring p recognition p _ carrier p enzymes channels
receptor
Membrane proteins include: anchoring p recognition p receptor p _ enzymes channels
carrier proteins
Membrane proteins include: anchoring p recognition p receptor p carrier p _ channels
enzymes
Membrane proteins include: anchoring p recognition p receptor p carrier p enzymes _
channels
_ proteins attach the plasma membrane to surround structures, providing stability
anchoring proteins
_ proteins act as receptors, essential for immune system usage
recognition
These proteins can be integral or peripheral:
enzymes
These proteins bind to extracellular molecules, or ligands:
receptor proteins
_ proteins bind solutes and delivers them across the membrane
carrier
These proteins form completely through the plasma membrane, as a passive flow of solutes
channels
Cytosol is the area within the cytoplasm that does not include the _
organelles
Cytosol is about 5% of the total cell volume
50
The _ is the site of many chemical reactions
cytosol
Cytosol mostly contains _, within which exist various dissolved particles
water
The various dissolved particles in the cytosol include: _ glucose amino acids fatty acids proteins, etc.
ions
The various dissolved particles in the cytosol include: ions _ amino acids fatty acids proteins, etc.
glucose
The various dissolved particles in the cytosol include: ions glucose _ fatty acids proteins, etc.
amino acids
The various dissolved particles in the cytosol include: ions glucose amino acids _ proteins, etc.
fatty acids
The various dissolved particles in the cytosol include: ions glucose amino acids fatty acids _, etc.
proteins, etc.
the organs of the cell are the_
organelles
Tiny specialized structures within the cell that have characteristic shapes, and perform specific functions in cellular growth, maintenance, and reproduction
organelles
Types of organelles incl
endoplasmic reticulum
cytoskeleton
ribosomes
Types of organelles include:
ribosomes
endoplasmic reticulum
cytoskeleton
endoplasmic reticulum
Types of organelles include:
ribosomes
endoplasmic reticulum
_
cytoskeleton
the site of proteins synthesis are
ribosomes
The network of membranes in the form of flattened sacs or tubules are_
endoplasmic reticulum (ER)
There are _ types of endoplasmic reticulum
2
The two types of ER are:
_
smooth
rough
The two types of ER are:
rough
_
smooth
T/F: Smooth endoplasmic reticulum (SER) do not have ribosomes
true
Smooth ER is the site of _ synthesis
lipid synthesis (fat makes things slippery and smooth)
Calcium ions are found in _ ER
smooth
Cardiac cells and skeletal muscle both contain _ ions
calcium
The _ is the powerhouse of the cell
mitochondria
The mitochondria of the cell makes _
ATP
T/F: not all cells require energy
false. energy is always needed for its survival
When a cell is active it will allow the tissue and then the _ to function
organ
Mitochondria are a form of _ in a cell
organelles
The network of protein filaments that extends through the cytosol is the _
cytoskeleton
The _ provides structural framework, and aids movement
cytoskeleton
The cytoskeleton provides _, and aids movement
provides structural framework
The cilia and flagella provide structural framework, and aids _
movement
There are _ types of protein filaments
3
The three types of protein filaments within the cytoskeleton are:
_
intermediate filaments
microtubules
microfilaments
The three types of protein filaments within the cytoskeleton are:
microfilaments
_
microtubules
intermediate filaments
The three types of protein filaments within the cytoskeleton are:
microfilaments
intermediate filaments
_
microtubules
Cytoskeletal filaments in the picture are shown as green, a.k.a. _
intermediate filaments
Cytoskeletal _ in the picture are shown in red.
microfilaments (teeny tiny, therefore need a bright colour to see them)
Microfilaments are composed of elements made of _
actin
Microfilaments are found mostly _ of the cell
at the edge (microfilaments are shy but strong, and are therefore at the edge of the party, but keep it together)
Microfilaments function to:
_
provide mechanical support
form microvilli
help generate movement
Microfilaments function to:
help generate movement
provide mechanical support
form microvilli
provide mechanical support
Microfilaments function to:
help generate movement
_
form microvilli
form microvilli
_ are extensions of the cell to the interior of the cell, forming hair-like projections, allowing the cell to move in place or over the cell
microvilli
Intermediate filaments are the _ in size of the filaments
medium
Intermediate filaments are a part of the cytoskeleton that functions to:
_
help position organelles
attach cells to one another
found in places where cells encounter stress
Intermediate filaments are a part of the cytoskeleton that functions to:
found in places where cells encounter stress
_
attach cells to one another
help position organelles
Intermediate filaments are a part of the cytoskeleton that functions to:
found in places where cells encounter stress
help position organelles
_
attach cells to one another
Intermediate filaments could be in the _ (organ) to protect it from rupturing or filling too much
bladder
The largest of the cytoskeleton components are _
microtubules
Microvilli allos the cell to _ by simply waving
move
Places where cells encounter stress you will likely see __
intermediate filaments
Intermediate filaments function to :
help position organelles
_
attach cells to one another
The _ of the cell creates stress on the cell, requiring the use of intermediate filaments to help position organelles, and attach cells to one another
constant movement
Microtubules are the largest of the _ components
cytoskeletal
Hollow tubes composed mainly of _ (a protein), which are the microtubules
tubulin (get it? microtubes are made from tubulin…you don’t get it)
Microtubules help:
determine cell shape
help the movement of organelles and
are found in _ and _
cilia and flagella (long finger-like structures that guide them, and create fluid-like movements of the organelles, etc.)
Microtubules are generally found as extensions of a _ in a cell
centrosome (just another structural element of the cytoskeleton. just gotta learn the centro-somes in the cyto-skeleton)
The centrosome has microtubules that radiate from it. It is a part of the _
cytoskeleton (since microtubules are associated with structure, it stands to reason that centrosome has microtubules that are a part of a greater structure, therefore the cytoSKELETON)
In images used to describe organelles of the cytoskeleton, the green colour refers to the _
cytofilaments (microtubules, intermediate filaments, and microfilaments; the green structural elements are like the trees within the forest)
The differences between organs is known as cell _
diversity (hello, Darwin)
What creates cell diversity?
fitting with the function of its use (things change based on its function. Its form is helpful in assisting it, too)
Cells differ greatly in several aspects:
size
shape
_
function (it had to be this or form!)
The three layers of the zygote that becomes the fetus are:
ectoderm
mesoderm
_
endoderm (the me in m-eme requires -eme)
Endoderm forms the _ organs
inner organs - lungs, thyroid, pancreas…
Ectoderm forms the _ organs
nervous system organs
Neural tissue _ and _ to changes in the body’s external and internal environemnt
detects and responds
Peripheral nervous system is found _
everywhere apart from the brain
Neural tissue is composed of
neurons
)
neuroglia - supportive cells
Supportive neural tissue is called _
neuroglia
Cells can sit on their own. T/R
false. They always exist in an environment
There are three types of muscle tissue:
skeletal muscle
cardiac muscle
_
smooth muscle
What is interesting about skeletal muscle cells? they are _
very long
_ muscle cells are short and rectangular, and branch into other cells
cardiac muscle cells
Differences between the muscle cells creates the different _
functions they perform
_ convert electrical signals into mechanical force and contract to generate movement
muscle tissue
_ cells are the only voluntary cells
skeletal muscle cells
T/R: smooth and cardia muscle cells are involuntary
true
Epithelial cells cover __
body surfaces
_ cells form lining of internal body surfaces and cavities
epithelial cells
Epithelial cells line hollow _ and ducts
organs
Epithelial cells’ major function is to provide a ___
protective barrier
The different forms of epithelial cells include:
_
subsequent layers (not a particular name)
lumen (specific to the lining of hollow organs
basement membrane (single and first layer
The different forms of epithelial cells include:
basement membrane (single, first layer)
___
lumen (specific to the lining of hollow organs
subsequent layers (not a particular name)
The different forms of epithelial cells include:
basement membrane (single, first layer)
subsequent layers (not a particular name)
lumen (specific to the lining of hollow organs
lumen (specific to the lining of hollow organs
Connect_ tissues are the most abundant and widely distributed onesive tissues
connective
Connective tissues serve to: _ supports strengthens protects and insulates internal organs major transport system within the body
binds tissues together
Connective tissues serve to: bind tissues together _ strengthens protects and insulates internal organs major transport system within the body
supports
Connective tissues serve to: bind tissues together supports _ protects and insulates internal organs major transport system within the body
strengthens
Connective tissues serve to: bind tissues together supports strengthens _ major transport system within the body
protects and insulates internal organs
Connective tissues serve to: bind tissues together supports strengthens protects and insulates internal organs _
major transport system within the body
The skin’s connective tissue is most easily seen by a sectional view of _ _ connective tissue
dense irregular
Skeletal muscle viewing is likely to see a sectional view of _ _ connective tissue
dense regular
Sectional view of adipose tissue would be found when looking at the connective tissue of _
the heart
Connective tissue forms _ to skeletal muscle to encourage its working
tendons
A sectional view of bone would see a ___, a type of connective tissue that surrounds an osteocyte (bone cell),
calcified extracellular matrix
_ is a connective tissue, with many different cells, like leukocytes, erythrocytes, and platelets
BLOOD
Leukocytes are…
white blood cells
Specialized comonents within the plasma membrane are considered _
cell junctions
_ hold cells together
cell junctions
Connective tissue can hold _ and _ together, but NOT _
tissues and organs, but NOT cells
There are different types of cell junctions, including: _ adherens desmosomes hemidesmosomes gap junctions
tight junctions
There are different types of cell junctions, including: tight junctions adherens _ hemidesmosomes gap junctions
desmosomes
There are different types of cell junctions, including: tight junctions adherens desmosomes hemidesmosomes _
gap junctions
Web-like strands of transmembrane proteins are called __
tight junctions
_ junctions’ role is to prevent the movement of substances between cells
tight junctions
Tight junctions fuse together the outer surfaces of adjacent ___
plasma membranes
T/F: Substances can pass alongside/between the edges of adjacent plasma membrane cells
false
Tight junctions disable substances from _____
passing alongside/between the edges of plasma membrane cells
How do substances pass when tight junctions exist?
they require permission through the cells themselves, rather than along the external walls
An example of an impenetrable barrier that uses tight junctions to prevent substances to get in is the…
blood brain barrier
_ move a bit, providing resistance to high mechanical stress to cells, and are a bit less impenetrable than tight junctions
desmosomes
The _ has some desmosomes that help protect cells in instances of high mechanical stress
heart
Organs that expand, such as the bladder, heart, lungs, skeletal muscle, are likely to have _ (cell junctions)
desmosomes
___ are little tunnels that form BETWEEN cells, allowing the exchange of cellular materials between cells
gap junctions
The exchange of cellular materials between cells through __ can include cytosol, ions, and signaling molecules
gap junctions
Gap junctions provide a way for cells to directly __
communicate with one another
There are _ main parts of a cell
three
Within the nucleus, each _, a single molecule of DNA associated withseveral proteins, contains thousands of hereditary units/genes that control most aspects of cellular structure and function
chromosome
The plasma membrane’s main function is to
separate the cell’s internal environment from the external environment
_ helps establish and maintain the appropriate internal environment for normal cellular activities
selectivity
What looks like a cut ham in a sectional view of a cell?
the nucleus
What composes the blue exterior of a sectional view of the cell?
the plasma membrane
What composes the brown and colourful elements of the middle of a cell?
the cytoplasm
T/F: does the cytosol include organelles?
No. The cytosol is separate
T/F: does the cytoplasm include organelles and the nucleus?
no, the cytoplasm is cytosol + organelle - nucleus
The fluid mosaic model is a structural model in the _
plasma membrane
A flexible yet sturdy barrier that surrounds and contains the cytoplasm of a cell is the
plasma membrane
T/F: the molecular arrangement of the plasma membrane resembles a solid set of lipids that contain a mosaic of many different proteins
false. The molecular arrangement resembles a CONTINUALLY MOVING SEA OF FLUID LIPIDS, within which contains a mosaic of many different proteins
Allowing the passage of several types of lipid-soluble molecules but act as a barrier for/from charged or polar substances suggests that the plasma membrane is…
flexible yet sturdy
The plasma membrane can serve as a barrier as well as a…
site of communication
Why is the plasma membrane a site of communication?
some proteins can act as signal RECEPTORS or as molecules that link it to intracellular or extracellular proteins
The plasma membrane has _ layers
2 = lipid bilayer
The lipid bilayer of the plasma membrane has lipids that have both polar and nonpolar parts. This suggests that the lipids are _ molecules
amphipathic
Amphipathic refers to the ___ of the plasma membrane
the water loving and fearing (hydrophilic and hydrophobic) phosphate containing heads of the lipid bilayer
The plasma membrane acts as:
a barrier separating the inside and outside of the cell
controls the flow of substances into and out of the cell
_
participates in intercellular signaling
helps identify the cell to other cells (e.g., immune cells)
Why are immune cells an example of the functions of the plasma membrane?
they help to identify the cell to other cells
The _ is a carbohydrate-enriched coating that covers the outside of many eukaryotic cells and prokaryotic cells, particularly bacteria
glycocalyx
Cholesterol molecules are weakly amphipathic, or are weak in their _. This is why they are interspersed among the other lipids in both layers of the plasma membrane
polarity
The tiny _OH group is the only polar region of _, and it forms hydrogen bonds with the polar heads of phospholipids and glycolipids
cholesterol
Integral proteins are typically _, with hydrophilic regions protruding into either the water extracellular fluid or the cytosol, and their hyrophobic regions extending among the fatty acid tails
amphipathic
A few integral proteins are tightly attached to one side of the plasma membrane bilayer by ___ to fatty acids
covalent bonding
Glycoproteins are often _ proteins, those with carobhydrate groups attached to the ends that protrude into the extracellular fluid
integral
The carbohydrates of glycoproteins are _, chains of 2 to 60 monosaccharides that may be straight or branched
oligosaccharides (oligo = few, saccharides = sugars)
The _ is formed by the carbohydrate portions of glycolipids and glycoproteins, forming an extensive sugary coat
glyocalyx
T/R: the pattern of carbohydrates in the glycocalyx is similar from one cell to another
false
The glycocalyx acts like a molecular “signature” that enables cells to _
recognize one another
A white blood cell’s ability to detect a “foreign” glycocalyx is one basis of the immune response that helps us destroy invading organisms. This receptor suggests that the pattern of carbohydrates in the glycocalyx…
varies from one cell to another
The glycocalyx enables:
cells to recognize one another
cells to adhere to one another in some tissues, and…
protects cells from being digested by enzymes in the extracellular fluid
Red blood cells are slippery as they flow through narrow blood vessels due to the _ properties of the glycocalyx which attract a film of fluid to many cells’ surface
hydrophilic
Other than making red blood cells slippery as they flow through narrow blood vessels, the glycocalyx protects cells found in the _ and the gastrointestinal tract from drying out
airways
T/F: whereas the types of lipids in cellular membranes vary considerably, the membranes of different cells and various intracelluar organelles have remarkably similar assortments of proteins that determine many of the membrane’s functions.
false. the types of lipids rarely change, whereas the membranes can easily differ
Some integral proteins form _, pore s or holes that specific ions, such as potassium ions (K+) can flow through to get into or out of the cell
ion channels
Most ion channels are _, allowing onlly a single type of ion to pass through
selective
Some integral proteins form ion channels, whereas others can be receptors and others _
carriers or transporters
Some integral proteins act as _, selectively moving a polar substance or ions from one side of the membrane to the other
carriers or transporters
Receptors that serve as cellular recognition sites are forms of
integral proteins
Each type of receptor recognizes and binds a specific type of _
molecular
Insulin _ bind the hormone insulin
receptors
A specific molecular that binds to a receptor, a type of integral protein, is called a _ of that receptor
ligand (liga = tied)
some integral proteins are _ that catalyze specific chemical reactions at the inside or outside surface of the cell
enzymes
Integral proteins may also serve as _ that anchor proteins in the plasma membranes of neighbouring cells to one another or to protein filaments inside and outside the cell. Peripheral proteins also serve as enzymes and _
linkers; linkers
_ proteins can serve as enzymes and linkers
peripheral
Membrane glycoproteins and glycolipids often serve as __
identity markers
The function of membrane glyocproteins and glycolipids as identity markers can enable a cell to:
recognize other cells of the same kind during tissue formation or…
recognize and respond to potentially dangerous foreign cells
A blood transfusion requires the blood type to be compatible with your own, or red blood cells may clump together. The ABO blood type _ are one example of cell-__
markers; cell-identity markers
Peripheral proteins help support the plasma membrane, anchor integral proteins and participate in ____
mechanical activities
Mechanical activities that peripheral proteins can take part in can include:
moving materials and organelles within cells
changing cell shape in dividing and muscle cells and…
attaching cells to one another
Membranes are _ structures
fluid
Neighbouring lipid molecules exchange places about _ times per second
10 million
Membrane fluidity depends both on the number of double bonds in the fatty acid tails of the lipids that make up the bilayer, and on …
the amount of cholesterol present
Each double bond puts a kink in the ____, which increases membrane fluidity by preventing lipid molecules from packing tightly in the membrane
fatty acid tail
_ allows the lipid bilayer to self-seal if torn or punctured
fluidity
An example of the self-sealing properties of bilipid layer membranes’ fluidity is the intracytoplasmic…
sperm injection to help infertile couples conceive
Because of the way it forms hydrogen bonds with neighbouring phospholipid and glycolipid heads and fills the space between bent fatty acid tails, _ makes the lipid bilayer stronger but less fluid at normal body temperature
cholesterol (higher temperatures, stronger and less fluid)
At low temperatures, _ makes the lipid bilayer less strong but more fluid at low temperatures
cholesterol (lower temperatures, less strong and more fluid)
An integral protein uses a ___ that forms a pore through which a specific ion can flow to get across a membrane
ion channel
T/F: most plasma membranes include specific channels for several common ions
true
Integral proteins use _ to transport a specific substance across a membrane by undergoing a change in shape
carrier/transporter
Amino acids, needed to synthesize new proteins, enter body cells via _
carriers/transporters
Integral proteins use _ which recognize specific ligands and alters cells’ function in some way
receptor
Antidiuretic hormone binds to _ in the kidneys, and changes the water permeability of certain plasma membranes
receptor
Integral and peripheral proteins use _ to catalyze reactions inside or outside a cell (depending on which direction the active site faces)
enzymes
Lactase, a type of _, protrudes from epithelial cells lining the small intestine, splitting the disaccharide lactose in milk as one drinks
enzyme
T/F: enzymes are a peripheral protein
false; they are an integral and peripheral protein
Integral and peripheral proteins use _ that anchor filaments inside and outside the plasma membrane, provide structural stability and shape for the cell
linkers
What proteins look siilar, and are both integral proteins?
ion channels and carriers/transporters
Receptor proteins recognize specific _
ligands
Enzymes __ inside or outside a cell
catalyze reactions
_ proteins, which are integral and peripheral, may also participate in movement of a cell or link two cells together
linker proteins
A type of glycoprotein that distinguishes your cells from anyone else’s (unless youa re an identical twin) are ____
cell identity markers
An important class of __ are the major histocompatibility (MHC) proteins
cell identity marker proteins
When stimulating a cell, the hormone insulin first binds to a protein in the plasma membrane. This action best represents which membrane protein function?
receptor proteins (integral)
T/F: The pattern of carbohydrates in the glycocalyx varies from one vell to cell to another
true
Since the pattern of carbohydrates in the glycocalyx varies from one cell to another, what can we assume that the glycocalyx enables?
the glycocalyx acts like a molecular “signature” that enables cells to recognize one another
A white blood cell’s ability to detect a “foreign” glycocalyx is one basis of the _ _ that helps us destroy invading organisms
immune response
The glycocalyx enables cells to ____ and protects cells from being digested by enzymes in the extracellular fluid
enables cells to adhere to one another
The hydrophilic properties of the eglycocalyx attract a ___ to the surface of many cells
film of fluid e.g., what makes red blood cells slippery as they flow through narrow blood vessels, and protects cells that line the airways and the gastrointestinal tract from drying out
What makes red blood cells slippery as they flow through narrow blood vessels, and protects cells that line the airways and the gastrointestinal tract from drying out, and how?
glycocalyx - attracts a film of fluid to the surface of cells due to its hydrophilic properties
T/F: the types of lipids in cellular membranes vary only slightly whereas the membranes of different cells and various intracellular organelles have remarkably different assortments of proteins that determine many of the membrane’s functions
True! There are 6 membrane proteins, either integral, peripheral, or both
Ion channels are _ proteins, pores or holes that specific ions, such as K+ can flow through to get into or out of the cell
integral
Most ion channels are _; they allow only a single type of ion to pass through
selective
Another type of integral protein are _, selectively moving a polar substance or ion from one side of the membrane to the other
carriers
Carriers are also knowns as _
transporters
Integral proteins called _serve as rcellular recognition sites. Each type of receptor recognizes and binds a specific type of molecular
receptors
Insulin receptors bind the hormone insulin. A specific molecular that binds to a receptor is called a _ of that receptor
ligand
Some integral proteins are _ that catalyze specific chemical reactions at the inside or outside surface of the cell
enzymes
Integral proteins may also serve as _ that anchor proteins in the plasma membranes of neighbouring cells to one another or to protein filaments inside and outside the cell.
linkers
Peripheral proteins also serve as enzymes and _
linkers
Membrane glycoproteins and glycolipids often serve as ___ .
cell-identity markers
Cell-identity markers may enable a cell to (1) recognize other cells of the same kind during ___
tissue formation
Cell-identity markers may recognize and respond to potentially dangerous ____
dangerous foreign cells
The _ blood type markers are one example of cell-identity markers
ABO
When you receive a blood transfusion, the blood type must be compatible with your own, or ____ may clump together
red blood cells
Neighbouring lipid molecules exchange places about ___ times per second, and may wander completely around a cell in only a few minutes
10 million times per second
Membrane fluidity depends both on the number of ___ in the fatty acid tails of the lipids that make up the bilayer, and on the amount of cholesterol present
number of double bonds in the fatty acid tails of the lipid bilayer
Each double bond in the fatty acid tail of the lipid bilayer puts _ in the tail
kink
A kink in the fatty acid tail increases membrane _ by preventing lipid molecules from packing _ in the membrane
fluid; tightly
Membrane fluidity enables the movement of the membrane components responsible for cellular process such as: cell movement growth division _ formation of cellular junctions self-sealing if torn or punctured
secretion
An important class of cell identity marker (glycoprotein) are the _ proteins
MHC proteins = major histocompatibility complex
_ are a group of genes that code for proteins found on the surfaces of cells that help the immune system recognize foreign substances. _ proteins are found in all higher vertebrates. In human beings, the complex is also called the human leukocyte antigen (HLA) system
major histocompatibility complex (MHC) group
The term _ means tahat a structure permits the passage of substances through it
permeable
Plasma membranes permit some substances to pass more readily than others; this property is termed ___
selective permeability
The lipid bilayer portion of the plasma membrane is highly permeable to nonpolar molecules such as _, carbon dioxide, and steroids
oxygen
The lipid bilayer portion of the plasma membrane is moderably permeable to small, uncharged polar molecules, such as water and urea, and impermeable to _ and large, uncharged polar molecules, such as _
impermeable to ions, and large, uncharged polar molecules, such as glucose
The lipid bilayer has a non/polar hydrophobic/hydrophilic interior
The lipid bilayer has a nonpolar, hydrophobic interior (pushes away water,
The more hydrophoboc or lipid-soluble a substance is, the _ the membrane’s permeability to that substance
greater
the ______ of the plasma membrane allows nonpolar molecules to rapidly pass through, but prevents passage of ions and large, uncharged polar molecules
hydrophobic interior
What benefit is there for polar molecules to not freely diffuse through a plasma membrane’s lipid bilayer?
it would easily throw off the intra- and extra-cellular balance. The ion channels selectively allow certain ions (e.g., K+ and Na+ in the potassium-sodium channels in the nervous system), as well as protect against the imbalance of waste, etc
Channels and carriers can be roles taken on by _ proteins
transmembrane proteins
_, such as proteins, are so large that they are unable to pass across the plasma membrane except by endocytosis and exocytosis
Macromolecules
A ___ is a difference in the concentration of a chemical from one place to another, such as from the inside to the outside of the plasma membrane
concentration gradient
Many ions and molecules are more concentrated in either the _ or the extracellular fluid, such as oxygen and sodium ions
cytosol
Carbon dioxide molecules and potassium ions are more concentrated in the _ than in the extracellular fluid
cytosol
typically the inner surface of the plasma membrane is more _ charged, and the outer surface is more _ charged
inner is negatively charged, outer surface is more positively charged
A difference in electrical charges between two regions constitutes an _
electrical gradient
Because it occurs across the gplasma membrane, the electrical gradient’s charge difference is termed the membrane _
potential (like a neuron’s action potential)
A substance will move across a plasma membrane downhill, or down its ____
concentration gradient
A _ charged substance will tend to move toward a _ charged area, and vice-versa
positively-charged substance to a negatively-charged area (i.e., potassium ions moving into a neuron to begin an action potential)
The combined influence of the concentration gradient and the electrical gradient on movement of a particular ion is referred to as its __
electrochemical gradient
In _ processes, a substance moves down its concentration or electrical gradient to cross tehe membrane using only its own kinetic energy (energy of motion)
passive
Kinetic energy is _ to the particles that are moving in passive processes across the membrane
intrinsic
An example of a passive process that has a substance move down its concentration or electrical gradient to cross the plasma membrane using only its own kinetic energy is ___
simple diffusion
In active processes, _____ is used to drive the substance “uphill” against its concentration or electrical gradient; it is usually in the form of ___
cellular energy; adenosine triphosphate (ATP)
An example of aan active process is ___
active transport
Other than an active transport, another way that some substances may enter and leave cells is in an active process in which tiny, spherical membrane sacs, referred to as _, are used
vesicles
Endocytosis, in which _ detach from the plasma membrane while bringing materials into a _
vesicles detach from the plasma membrane while bringing materials into a cell
_ is the merging of vesicles with the plasma membrane to release materials from the cell
exocytosis
_ is a passive process in which the random mixing of particles in a solution occurs because of the particles ‘ kinetic energy
diffusion
The _, the dissolved substances, and the _, the liquid that does the dissolving, under diffusion
solute;
solvents
e.g., sodium bicarbonate (solutes), and water (solvent)
IF a particular solute is present in high concentration in one area of a solution and in low concentration in an other area, solute molecules will diffuse toward the area of _ concentration
lower
When solute molecules diffuse toward the area of lower concentration, they are said to move ________
down their concentration gradient
When particles become evenly distributed through a solution (across membranes), the solution is said to be ____
at equilibrium
Several factors influence the diffusion rate of substances across plasma membranes:
_ of the concentration gradient
steepness; the greater the difference in concentration between the two sides of the membrane, the higher is the rate of diffusion
When _ _ are diffusing, the steepness of the electrochemical gradient determines the diffusion rate across the membrane
charged particles
T/F: At equilibrium, a solution’s concentration is uniform through, and therefore movement does not occur
false: random movement continues
Several factors influence the diffusion rate of substances across plasma membranes:
the higher the _, the faster the rate of diffusion. All of the body’s diffusion processes occur more _ in a person with a fever
temperature;
Several factors influence the diffusion rate of substances across plasma membranes:
the larger the _ of the diffusing particle, the _ its diffusion rate. _ molecules diffuse more rapidly than _ ones
mass of the diffusing particle;
the larger the particle, the SLOWER its diffusion rate. Smaller ones diffusion more quickly than larger ones
Several factors influence the diffusion rate of substances across plasma membranes:
_____
e.g., air sacs of the lungs have a larger ___, available for diffusion from the air into the blood. Some lung diseases, such as emphysema, reduce the __, slowing the rate of oxygen diffusion and making breathing more difficult
air sacs of the lungs have a larger SURFACE AREA, available for diffusion from the air into the blood. Some lung diseases, such as emphysema, reduce the SURFACE AREA, slowing the rate of oxygen diffusion and making breathing more difficult
Several factors influence the diffusion rate of substances across plasma membranes:
diffusion across a plasma membrane takes only a fraction of a second because the membrane is so _. In pneumonia, fluid collects in the lungs; the additional fluid increases the diffusion _ because oxygen must move through the built-up fluid and the membrane to reach the bloodstream
diffusion across a plasma membrane takes only a fraction of a second because the membrane is so thin (not distant). In pneumonia, fluid collects in the lungs; the additional fluid increases the diffusion DISTANCE because oxygen must move through the built-up fluid and the membrane to reach the bloodstream
Several factors influence the diffusion rate of substances across plasma membranes: temperature mass of the diffusing substance surface area diffusion distance \_\_\_\_ of the concentration gradient
steepness of the concentration gradient (greater the difference in concentration between the two sides of the membrane, the higher the rate of diffusion)
_ is a passive process in which substances move freely through the lipid bilayer of the plasma membranes of cells without the help of membrane transport proteins
simple diffusion
, hydro molecules move across the lipid bilayer through the process of simple diffusion
Polar, hydrophobic molecules move across the lipid bilayer through the process of sof simple diffusion
Molecules such as oxygen, carbon dioxide, and nitrogen gases; fatty acids; steroids; and fat-soluble vitamins are move across membranes by ____
simple diffusion
Fat-soluble = hydro_
hydrophobic
Small, uncharged polar molecules such as water, urea and small alcohols also pass through the lipid bilayer by ___, in addition to nonpolar, hydrophobic molecules
simple diffusion
_ through the lipid bilayer is important in the movement of oxygen and carbion dioxide between blood and body cells, and between blood and air within the lungs during breathing
simple diffusion
_ is the route for absorption of some nutrients and excretion of some wastes by body cells
Simple diffusion
Solutes that are too polar or highly charged to move through the lipid bilayer can cross the plasma membrane by a passive process called ___
facilitated diffusion
In facilitated diffusion, a _____ membrane protein assists a specific substance across the membrane. The __ can be either a membrane channel, or a carrier
integral member protein that is a channel or carrier can assist facilitated diffusion
In ______ diffusion, a solute moves down its concentration gradient across the liid bilayer through a membrane channel
channel-mediated facilitated diffusion (CMFD)
Most membrane channels are _ channels, integral transmembrane proteins that allow passage of small, inorganic ions that are too hydrophilic to penetrate the nonpolar interior of the lipid bilayer
ion channels allow passage of small, inorganic ions that are too hydrophilic to penetrate the nonpolar interior of the lipid bilayer
T/F: Ions can diffuse across the membrane only at certain sites
true. in typical plasma membranes the only numerous ion channels are selective for K+ or cl-
A channel is said to be _ when part of the channel protein acts as a plug or a gate, changing shape in one way to open the pore and in another way to close it
gates
T/F: gated channels randomly alternate between open and closed positions; others are regulated by chemical or electrical changes inside and outside the cell
true
T/F: cellular energy is used for carrier-mediated facilitated diffusion (i.e., a carrier/transporter moves a solute down its concentration gradient across the plasma membrane
false. It is a passive process, so no cellular energy is required
What has to happen to the carrier/transporter in carrier-mediated facilitated diffusion in order to facilitate the distribution of a solute along a plasma membrane?
the solute binds to a specific carrier on one side of the membrane, and is released on the other side AFTER THE CARRIER UNDERGOES A CHANGE IN SHAPE
The solute binds more often to the carrier/transporter on the side of the membrane with a _ concentration of solute (i.e., carrier-mediated facilitated diffusion)
higher concentration of solute, as it is more likely to move to the lower concentration
Gated channels distribute _, which explains why the sodium-potassium channel is gated
ions
Channels are _ membrane proteins that allow specific, small, inorganic ions to pass across the membrane by facilitated diffusion
integral
An upper limit on the rate at which facilitated diffusion can occur with carriers availability in a plasma membrane is called the _ _
transport maximum
Substances that move across the plasma membrane by carrier-mediated facilitated diffusion include glucose, fructose, galactose, and some _
vitamins
_, the body’s preferred energy source for making ATP, enters many body cells by carrier-mediated facilitated diffusion as follows
glucose
Glucose binds to a specific type of carrier protein called the ___, on the outside surface of the membrane
glucose transporter
GluT is… _, a type of carrier protein
glucose transporter, a type of carrier protein, on the outside surface of the membrane
Glucose binds to a the glucose transporter on the _ surface of the membrane
outside
Glucose transporters are carrier proteins that are on the outside of membrane, since glucose is likely to be on the _ of cell in the _cellular fluid, from where energy could be accessed to the body after having gone through the digestive system
outside; extracellular
Theh hormone _, via the action of its receptor, promotes the insertion of many copies of glucose transporters into the plasma membranes of certain cells. Thus, the effect of _ is to elevate the transport maximum for facilitated diffusion of glucose into cells
insulin!
With more glucose transporters available, body cells can pick up glucose from the blood more rapidly thanks to insulin. An inability to produce or utilize insulin is called _ _
diabetes mellitus
In layman’s terms, what does insulin do?
it enables the body’s membranes to facilitate the diffusion of glucose into cells. If not, one’s blood gets too high in sugar levels, reducing the ability for the body get appropriate energy, and…something else for which I’ll figure out later
_ is a type of diffusion in which there is net movement of a solvent through a selectively permeable membrane; typically water is what moves across the membrane
osmosis
Water moves through a selectively permeable membrane from an area of _ solute concentration to an area of _ solute concentration
lower to higher. Why? because there would actually be less water in the higher solute concentrate, so it is still going to an area with relatively less water, much like other diffusion
During osmosis, water molecules pass through a plasma membrane in two ways:
by moving between neighbouring phospholipid molecules in the lipid bilayer via simple diffusion, and by moving through _
aquaporins
During osmosis, water molecules can pass through a plasma membrane through _, integral membrane proteins that function as water CHANNELS
aquaporins (not aqua channels, but aquaporins)
Osmosis is the movement of water molecules through a ___ membrane
SELECTIVELY permeable membrane
The restoring element that ensures water levels are in the appropriate volumes during osmosis is the addition of ___; it is applied to the solution in the side with a HIGHER volume to ensure equal volume across membranes
osmotic pressure, a typic of applied pressure
Pressure exerted on the side of a membrane with rising water volume, reducing the solute concentration along a gradient is known as _ pressure
hydrostatic
The movement of water into one side of a membrane to not completely remove water from its side is called _ pressure
hydrostatic pressure
T/F: osmotic pressure of a solution does not produce the movement of water during osmosis
True. It is hydrostatic pressure
T/F: Osmotic pressure prevents water moving from a solution on one impermeable membrane to another (i.e., NOT producing movement of water during osmosis)
true. It is hydrostatic pressure that moves the water from one side to the next
A solution’s _ is a measure of the solution’s ability to change the volume of cells by altering their water content
tonicity (tonic - tension)
Any solution in which a cell-_for example, a red blood cell–maintains its normal shape and volume is __ solution
isotonic solution (iso-same, tonic-tenson)
The concentration of solutes that cannot cross the plasma membrane are ____ on the sides of the membrane in this solution
similar; what is normal enables constant water movement in cells such as red blood cells, but it behaves as though it is impermeable to Na+ and Cl- in the solutes which are sent back from where they came if moving along it; the cells maintain their normal shape and volume
If RBC (red blood cells) are placed in a hypotonic solution, water molecules enter the cells faster than they leave, causing the RBCs to swell and eventually to burst since the solutation that has a _ concentration of solutes than the cytosol in side the RBCs
lower
A solution that has a LOWER concentration of solutes than the cytosol inside the cell would be a _ solution; in this case, water molecules enter the cells faster than they leave, causing the cells to swell and eventually to burst
hypotonic (hypo-less than, tonic-tension); lower concentration of solutions means higher degree of water outside, suggesting water rushes INTO the cell
The rupture of red blood cells from being in a hypotonic environment is called _,
hemolysis (hemo-blood, -lysis- to loosen or split apart)
The rupture of cells OTHER THAN RED BLOOD CELLS, due to placement in a hypotonic solution is referred to as _. Pure water is very hypotonic, and causes rapid hemolysis
lysis
A _ solution has a higher concentration of solutes than does the cytosol inside red blood cells
hypertonic (hyper-greater than, tonic-tension), with lower degree of water outside the cells, causing water to leach out of the cells
One example of a _ solution is a 2% NaCl solution. In such a solution, water molecules move out of the cells faster than they enter, causing the cells to shrink.
hypertonic (lower degree of water, higher degree of solutes outside of the cells)
The shrinkage of cells due to lysis (or hemolysis in red blood cells) is called _
crenation
We generally prefer cells to be surrounded by _ solutions, whereas _ ones would create water-logged cells, and _ ones would create water-depleted/crenated ones
isotonic preferred;
hypotonic causing water to rush in;
hypertonic causing water to rush out
_ solutions have a higher concentartion of solutes than the cytosol, encouraging water to move out of cells faster than they enter, causing cells to shrink, called crenation
hypertonic
Intravenous (IV) solutions are liquids infused into teh blood of a vein are _.
isotonic
Sometimes infusion of a _ solution such as mannitol (sugar alcohol) is useful to treat patients who have excess interstitial fluid in the brain, or cerebral edema
HYPERTONIC
Infusion of mannitol in an IV solutionrelieves fluid overload by causing osmosis of _ water from _ fluid into the _
interstitial fluid into the blood
_ excrete excess water from the blood into waste, or urine
kidneys
_ solutions, given either orally or through an IV, can be used to treat people who are dehydrated
hypotonic
The water in the _ solution moves from the blood into interstitial fluid and then into body cells to rehydrate them. Water and most sports drinks that you consume to rehydrate after a workout are _ relative to your body cells
hypotonic
Why would a 2% NaCl be a hypertonic solution?
because it would leach the water out of one’s body cells into the interstitial fluid, likely causes crenation, or the shrinkage of cells
Water and most sports drinks have less solutes than one’s cells, therefore it would incline the body to rehydrate. Too much water or sports drinks, or _ solutions, could create so much water into the fluid as to…In red blood cells, this process is called hemolysis
hypotonic;
cause the cells to swell and eventually rupture
Active transport requires energy for carrier proteins to move solutes across the membrane against a…
concentration gradient
Two sources of celular energy can be used to drive active transport:
energy obtained from hydrolysis of adenosine triphosphate (ATP), the source of primary active transport; and
energy stored in ____ concentration gfradient, the source of secondary active transport
ionic (remember: it is easier to release transport by creating energy than conjuring ionic changes along the membrane
Like carrier-mediated facilitated diffusion, active transport processes exhibit a transport maximum and _
saturation. it would be beneficial to have limits on the number and types of solute ions and acids to cross, limiting the possibility of complications in the body
T/F: some of the substances that are transported across the plasma membrane by active transport also cross the membrane via facilitated diffusion when the proper channel proteins or carriers are present
true
Solutes actively transported across the plasma membrane incude:
several ions, such as Na+, K+, _, Ca2+, I-, and Cl-
H+
Solutes actively transported across the plasma membrane include several ions, amino acids, and _
monosaccharadies
Hydrolysis of ATP changes the shape of a carrier protein, which “pumps” a substance across a plasma membrane against its concentration gradient. This is referred to as ____
primary active transport
Primary active transport moves _ its concentration gradient
against
Carrier proteins that mediate primary ACTIVE transport are often called _
pumps e.g., sodium-potassium pump
A typical body cell expends about _ of the ATP it generates on primary active transport
40%
Chemicals that turn off ATP production, such as _, are lethal because they shut down active transport in cells throughout the body
the poison cyanide
The most prevalent primary active transport mechanism expels _ ions from cells, and brings _ ions in, referred to as the - pump
sodium out (we want less salt in our bodies), and bring potassium in (eat bananas!), referred to as the sodium-potassium pump
the sodium-potassium pump is also called the _____ because a part of it acts as an _ase, an enzyme that hydrolyzes ATP
Na+ K- ATPase
All cells have _ of sodium-potassium pumps in their plasma membranes
thousands
Low concentration of Na+ in the _ exists by pumping these ions into the _ against the Na+ gradient
less sodium in cytosol, higher in the extracellular fluid for when it’s needed (sodium then rushes into the cells in order to begin active potentials. They wouldn’t have much potential if they weren’t inclined to go against the curve)
How are Na+ and K+ ions leaked back across the plasma membrane down their electrochemical gradients?
through passive transport or SECONDARY active transport
How often does the sodium-potassium pumps of cells work?
constantly, otherwise it would be less likely that Na+ would be in low concentration, and K+ in high concentration in the cytosol
How many Na+ ions are needed to be expelled from the cytosol triggering ATP?
3 IONS
3 sodium ions from the cytosol ibind to the inside surface of the sodium-potassium pump. What does this binding trigger to bind to the pump, and what is it split into?
ATP is triggered to bind to the sodium-potassium pump and split into ADP and P (phosphate)
The energy from ATP splitting causes the channel PROTEIN to change shape, which serves to…
move the Na+ ions (3 ) to the outside of the cell, into the extracellular fluid
The expulsion of 3 Na+ ions coincides with 2 potassium ions landing to the outside surface of the pump, and cause the _ to be released
the phosphate split from ADP (adenosine DIphosphate) bound to the interior wall of the plasma membrane (phosphate = P)
The release of the phosphate (P) back into the cytosol causes the sodium-potassium pump to…which moves the K+ into the cell
return to its original shape (imagine the potassium ions being stuck in the middle of the plasma membrane in the transporter protein, finally being allowed to move in because of the phosphate release)
How many actions occur in the sodium-potassium pump?
4
What are the ions involved in the sodium-potassium pump?
sodium (extracellular; 3), potassium (intracellular; 2), and phosphate (intracellular; 1); the molecules of adenosine diphosphate (1) are also involved from which phosphate is split from to become adenosine triphosphate
Are the sodium ions in the cytosol when the potassium ions return to it also?
No. The Na+ ions move along a gradient into the cytosol as the K+ move out of it. Then 3 Na+ ions bind to the inside surface of the pump, triggering the reaction that moves the Na+ ions back out again, after which the K+ ions return
The different concentrations of Na+ and K+ in cytosol and extracellular fluid are crucial for maintaining normal __ and for the ability of some cells to generate electrical signals such as action potentials
normal cell volume (remember, hypertonic solutions leach water out of the cell causing crenation [lysis], whereas hypotonic add too much water into cells, causing them to swell and burst)
Because a Na+ or H+ gradient is established by primary active transport, secondary active transport _ uses energy obtained from the hydrolysis of ATP
indirectly
As Na+ is leaked into the cell, some of the stored energy can be converted to _ energy, and used to transport other substances against their concentration gradients
kinetic
Secondary active transport proteins harness the energy in the Na+ concentration gradient by providing routes for Na+ to leak into cells. If this carrier protein binds Na+ to another ion moving in the same direction, the protein is called a _
symporter (sym=same)
Secondary active transport proteins harness the energy in the Na+ concentration gradient by providing routes for Na+ to leak into cells. If this carrier protein binds Na+ to another ion, but that ion moves in an opposite direction, the protein is called a _
antiporter (anti- against)
T/F: Plasma membranes contain several antiporters and symporters that are powered by the Na+ gradient, such as the Na+-Ca2+ antiporters’ role that expel calcium ions as sodium ions are introduced to the cell
True. Calcium is expelled as sodium ions are introduced to the cell. This is because calcium is in low quantities inside the cell, and wants to go where less of it exists
T/F: Plasma membranes contain several antiporters and symporters that are powered by the Na+ gradient. A carrier protein that regulates the cytosol’s pH concentration (i.e., H+), is a symporters, helping to regulate the cytosol by expelling excess H+
False. By expelling H+, the carrier protein is moving the ions in a different from the incoming Na+ ions. Therefore, the carrier protein is an antiporter, not a symporter
T/F: Dietary glucose and amino acids are absorbed into cells that line the small intestine by Na_ -glucose and Na+-amino acid symporters
True. Sodium ions moving down their concentration gradient while the other solutes move “uphill”, against their concentration gradients (that’s why this takes so much energy, because low numbers of glucose is going to where it is higher, requiring greater amounts of energy than if left to its own devices - moving from high to low concentrations along a membrane)
Active transport requires energy for carrier proteins to move solutes across the membrane AGAINST a concentration gradient, whereas passive transport…
uses kinetic energy, and is likely to go down its concentration gradient (i.e., from high concentration to low)
_ often is given to patients with heart failure, increasing CA2+ in heart muscle cells, weakening pumping action by the heart. It exerts its effect by slowing the action of sodium-potassium pumps which lets more Na+ accumulate inside heart muscle cells, decreasing the Na+ concentration across the membrane, causing Na+Ca2+ antiporters to slow down, keeping mroe Ca2+ in the heart muscle cells. This forces greater contracts and the force of the heartbeat
Digitalis screws up the Na+Ca2+ antiporters, keeping the Na+ inside, keeping Ca2+ inside too
Na+ bound with H+ or Ca2+ ions use _ carrier proteins, whereas Na+ bound with glucose or amino acids use _ carrier proteins
antiporters for Ca2+ and H+ (these two exiting while Na+ enters), and symporters for glucose and amino acids (going into the cell along with Na+)
Vesicles transport substances between cell structures, and…
import materials from, and release materials into, extracellular fluid
Vesicles use _ to move materials into a cell
endocytosis (endo- within)
Vesicles use _ to move materials out of a cell by the their fusion with the plasma membrane formed inside the cell
exocytosis (exo-out)
Both endocytosis and exocytosis require energy supplied by _, making transport in vesicles ___ process
energy supplied is ATP, making vesicle transport an active process (primary, whereas a secondary one would use carrier proteins combined with the movement of Na+ ions)
What does endocytosis look like?
lava lamps, with its movement forming from a flat top and then plopping down into a ball that eventually settles elsewhere
Receptor-mediated endocytosis is the first of _ types of endocytosis
three
Receptor-mediated endocytosis is a highly selective type by which cells take up specific _
ligands; remember, ligands are molecules that bind to specific receptors
A vesicle forms after a receptor protein in the plasma membrane recognizes and binds to a particular particle in the ___
extracellular fluid (it is a transporter, so the vesicle transports a particle along the membrane into the cell’s cytoplasm
Receptor-mediated endocytosis enables cells take up cholesterol-containing low-density lipoproteins (LDLs), transferrin (iron-transporting protein in blood), vitamins, antibodies, and certain _
hormones
Receptor-mediated endocytosis moves like a lava lamp into and along the cell, using _ steps
6
The 6 steps of receptor-mediated endocytosis are:
1) binding
2) vesicle formation
3) uncoating
4) fusion with endosome)
5) _
6) degradation in lysosomes
recycling of receptors to plasma membrane
So what happens is that LDL outside the cell contains cholesterol that binds to a receptor…which leads to the vesicle’s formation, and once formed leads to an exterior uncoating, and later fusion with an endosome. Once its role has been fulfilled, it is recycled into the plasma membrane and breaks down in lysosomes
The receptors of receptor-mediated endocytosis are integral membrane proteins that are concentrated in regions of the plasma membrane called _-coated pits
clathrin-coated pits; a type of protein with its molecules creating a basket (clathrin holds a basket of molecules, picking up the LDLs; They’re “heavy”, so they cause the cell to fold inward, bringing them in, much like how a lava lamp moves
The vesicles are formed by the fusing of the clathrin-coating, creating a _ vesicle, containing the receptor-LDL complexes. This happens by the membrane forming around the coating, and a small piece of the membrane pinches off
clathrin-coated vesicle
T/F: does the clathrin-coated vesicle keep its clathrin coat for a while?
hell no. almost immediately after it is formed it becomes uncoated, an uncoated vesicle
Clathrin molecules, no longer coating a vesicle, return to the inner surface of the plasma membrane, or help _
form coats on other vesicles inside the cell
What happens to the uncoated vesicle shortly after uncoating?
the uncoated vesicle quickly fuses with an endosome, another vesicle, within which the LDL particles separate from their receptors
What happens to the LDL when an uncoated vesicle fuses with an endosome?
the LDLs separate from their receptors
What happens once the LDL particles separate from their receptors within an endosome (vesicle)?
receptors are recycled to the plasma membrane
they accumulate in the endosome. Their elongated protrusions pinch off, and forming transport vesicles that return the receptors to the plasma membrane
What accumulates in the elongated protrusions of the endosome, which are then pinched off, and form transport vesicles that return it to the plasma membrane?
receptors
What is the process called that is the accumulation of receptors in the elongated protrusions of the endosome, whichare then pinched off, and form transport vesicles that return it to the plasma membrane?
recycling of receptors to the plasma membrane
What is the last step of receptor-mediated endocytosis?
degradation of LDL particles in lysosomes
What is it about lysosomes that cause the degradation of some transport vesicles?
lysosomes contain digestive enzymes that break down the lipid molecules of LDL particles
The steps of receptor-mediated endocytosis involves:
binding of the vesicle to clathrin
formation of the vesicle as clathrin-coated
vesicle fusion with endosome
recycling of receptors
_
degradation in lysosomes
The three forms of endocytosis are:
receptor-mediated endocytosis
phagocytosis and…
bulk-phase endocytosis
Phagocytosis is a form of endocytosis in which the cell ___, such as worn-out cells, whole bacteria or viruses, using phagocytes
engulfs whole particles (phagocytosis = phago-eat)
Macrophages and neutrophils are the two main types of _
phagocytes
Neutrophils are a type of _, also a phagocyte
white blood cell
_, contained in many tissues, is a type of phagocyte
macrophages
Phagocytosis begins when the article binds to a plasma membrane receptor on the phagocyte, causing it to extend ____, projections of its plasma membrane and cytoplasm
extend pseudopods (pseudo-false, pods-feet)
Pseudoods surround the particle outside the cell in phagocytosis, and the membranes fuse to form a vesicle called a _
phagosome
What happens to the phagosome once membranes fuse to form it after pseudopods surround the particle outside the cell?
the phagosome enters the cytoplasm (what happens once something surrounds something? it moves, and then it changes location [into the cytoplasm])
the phagosome fuses with one or more _ once it enters the cytoplasm, and _ enzymes break down the ingested material
lysosomes (lysosomes fuse with phagosomes, which contain enzymes that break down the particle that’s in it. It’s not too complicated)
In most cases, any undigested materials in the phagosome remain indefinitely in a vesical called a _; they are then either secreted by the cell via exocytosis or they remain stored in the cell as lipofuscin granules
residual body (what remains of phagosome’s disintegration, that which is the residue of the phagosome’s body, or the residual body)
Bulk-phase endocytosis, or _, is a form of endocytosis in which tiny droplets of extracellular fluid are taken up
pinocytosis (pino-drink); (you drink pinot noir, and those tiny droplets of wine are taken up into the cell without receptor proteins - you don’t need anyone to help you enjoy it now, do you? Also, damn right you are going to have a bulk-phase when you have too much pinot)
T/F: All solutes dissolved in the extracellular fluid during pinocytosis (bulk-phase endocytosis) are brought into the cell
true. Damn right that if I drink a glass of wine, I’m going to enjoy the whole damn thing
During bulk-phase endocytosis/pinocytosis, the plasma membrane folds inward and forms a vesicle containing ____. The vesicle detaches or “pinches off” fromt he plasma membrane and enters the cytosol.
The vesicle in pinocytosis contains a droplet of extracellular fluid (there is one drop of fluid per vesicle in pinocytosis? damn. No wonder pinot costs so much)
Once a vesicle during pinocytosis enters the cytosol, the vesicle fuses with a __, where enzymes degrade the engulfed solutes
lysosomes, lysosomes, lysosomes. They contain those damn enzymes that break everything up. It’s like Lysol for your vesicles and what contain them
Bulk-phase endocytosis occurs in most cells, especially absorpitive cells in the intestines and _
kidneys - they are charged with absorbing liquid for which the waste is later extracted into urine. Gotta have that pinocytosis
In contrast with endocytosis, exocytosis ___ materials _ a cell
releases materials from a cell (you absorb pinot in pinotcytosis, but stuff takes an exit in exocytosis
T/F: only some cells carry out exocytosis
False. Hello no! every cell needs to get rid of things whether it’s microbes fluid, ions, enzymes, mucus, hormones, what have you. EVERY cell needs to get rid of items using exocytosis (it’s like everybody needs to go to the toilet to urinate, eventually)
Although all cells use exocytosis, the most important ones are:
secretory cells that liberate digestive enzymes, hormones, mucus, or other secretions, and
___ that release…
neurons that release neurotransmitters (imagine holding onto neurotransmitters and never releasing them. They wouldn’t move through neurons! That’s why neurons use exocytosis from the brain to the other regions of the body, through the spinal cord
Are wastes released by exocytosis? If so, what kind of vesicles would form to release them?
sometimes; secretory vesicles (let’s phase it: secretary’s sometimes have to get rid of evidence when bosses are trying to make a quick exit)
Enlarged 450x, a white blood cell engulfs a microbe with pseudopods. This takes roughly _ sec.
20 seconds (it takes 2 sets of hands or 2 tries of 10 fingers to bring them in - pseudopods)
Enlarged 450x, a white blood cell destroys a microbe roughly within _ sec
60 seconds (sometimes it takes a whole minute before you release a microbe of a guy is your date before he can be destroyed)
T/F: Exocytosis is a vital defense mechanism hat helps protect the body from disease. Macrophages dispose of invading microbes and billions of aged, worn-out red blood cells every day; neutrophils also help rid the body of invading microbes.
false. Phagocytosis!
_ is a mixture of dead neutrophils, macrophages, and tissue cells and fluid in an infected wound
pus (phagocytosis can elicit pus from a wound)
The _/intracellular fluid ids the fluid portion of the cytoplasm that surrounds organelles
cytosol
Cytosol constitutes about _% of total cell volume
55
Cytosol is 75-90% water plus various dissolved and suspended components. Among thesea re different types of ions, glucose, amino acids, fatty acids, proteins, lipids, ATP, and ___
waste products
Organic molecules can aggregate into masses for storage in the cytosol. these aggregations may appear and disapppear at different times in the life of a cell. examples include lipid droplets that contain triglycerides, and clusters of glycogen molecules called ___
glycogen granules
Enzymes in cytosol catalyze _, a series of 10 chemical reactions that produce 2 molecules of ATP from one molecule of glucose
glycolysis
The _ is a network of protein filaments that extends throughout the cytosol
cytoskeleton
Microfilaments are composed of actin and _, and are most prevalent at the edge of a cell
myosin
Microfilaments are involved with ____, cell division, locomotion, invasion of tissues by white blood cells to fight infection, or the migration of skin cells during wound healing
muscle contraction
Are microvilli motile?
no
Because they greatly increase the surface area of the cell, _ are abundant on cells involved in absorption, such as the epithelial cells that line the small intestine
microvilli are abundant in epithelial tissue, in the small intestine
Microtubules form around the centrosome like…
legs of a spider
Cilia move fluids along a _
cell’s surface
Flagella move _
cells
What is an example of a flagellum?
the tail of a sperm cell, which moves it towards the ovum
A cilium contains a core of _ with one pair in the center, surrounded by nine clussters of doublet _
microtubules
What is the ciliary movement?
the movement of liquid according to the movement of the cilium along the cell’s surface; it has a “come hither” feel
What is the flagellar movement?
like a tail, it moves in the opposite movement of the cell, propelling it forward
The movement of cilia is paralyzed by _, which predicts that _ cought often to remove foreign particles from their airways
nicotine; smokers cough
Cilia sweep _ toward the uterus, and females who smoke have an increased risk of _
oocytes (egg cells); ectopic pregnancy
Each cilium contains a core of 20 _ surrounded byplasma membrane
microtubules
Microtubules in a cilium are arranged such that one pair in the centre is surrounded by _ of two fused microtubules (doublets
nine clusters around a single pair (although the clusters are each two fused microtubules)
Although I consider it a “come hither” movement, the cilium is said to display ___ pattern of beating
oarlike
Each cilium is anchored to a __ just below the surface of the plasma membrane
basal body
A basal body is similar in structure to a _, and functions in initiating the assembly of cilia and flagella
centriole
Ribosomes associated with endoplasmic reticulum synthesize proteins destined for ___, or secretion from the cell
insertion in the plasma membrane
Free ribosomes synthesize proteins used in ___
the cytosol
Ribosomes are the site of protein synthesis. Their name reflects their high content of ___, although each one includes more than 50 others
ribonucleic acid, RNA
Ribosomes consist of two subunits, one twice the size of the other, made separately in the _
nucleolus
Ribosomes are concerned with the synthesis of proteins, whether it’s for the plasma membrane, specific organelles, or to ___
export from the cell
Free ribosomes are used to synthesize
proteins used in the cytosol
Do mitochondria contain ribosomes?
yes, for synthesizing mitochondrial proteins
In latin, -plasmic refers to _, and reticulum to network. Hence, the __ is a network of membranes in the form of flattened saces or tubules, from the nuclear envelop to the cytoplasm
endoplasmic reticulum
Rough endoplasmic reticulum is often studded on its exterior with ribosomes, and sometimes with enzymes to form glycoproteins with carbohydrates, otherwise with ____
phospholipids and enzymes
Ribosomes synthesize items, which create an entirely new item from two products, whereas rough endoplasmic reticulum ___
produces, or creates an initial product
Smooth ER is good for synthesizing ____ and __, whereas rough ER synthesizes ____
Smooth ER = steroids and fatty acids, enzymes; rough ER = glycoproteins, secretory, and membrane (with the addition or ribosomes)
smooth ER help synthesize hormones and fatty acids, as well as inactivates or detoxifies fat-soluble drugs or potentially harmful substances, such as alcohol, pesticides, and __
carcinogens
In liver, kidney, and intestinal cells, a ___ removes the phosphate group from glucose-6-phosphate, which allows the “free glucose to enter the bloodstream
smooth ER enzyme
In _ cells, the calcium ions that trigger contraction are released from the sarcoplasmic reticulum, a form of smooth ER
muscle cells
Individuals who take drugs repeatedly, such as sedative phenobarbital develop changes in the ___ in their liver cells
smooth ER
Prolonged administration of phenobarbital results in increased tolerance to the drug. with repeated exposure to the drug, the amount of ____ and its enzymes increases to protect the cell from its toxic effects
smooth ER
Golgi complex have small, flattened membranous sacs with bulging edges that resemble a stack of pita bread, likely because they aid in…
cells that secrete proteins, likely gathering them as they are produced
Golgi complex consist of 3 to 20 _, or cavities, used to gather proteins
cisternae
In a _ section, one is likely to see smooth ER, ribosomes, and rough ER of a cell
transverse (along its middle, like a slice)
___ modifies, sorts, packages, and transports proteins received from the rough ER
Golgi complex - it is a convex-medial-concave structure that can deal with proteins that are synthesized by the rough ER and meant for various parts of the cell
Golgi complex forms ___ that discharge processed proteins via exocytosis into extracellular fluid
secretory vesicles
Golgi complex form __ that ferry new molecules to the plasma membrane
membrane vesicles
Golgi complex forms ___ that carry molecules to other organelles, such as lysosomes
transport molecules
Exit cisternae are more _ than medial, which are more than entry
mature
Proteins arriving at, passing through, and exiting the Golgi complex do so through maturation of the cisternae and exchanges that occur via ___ vesicles
transfer
Proteins synthesized by ribosomes on the rough ER are surrounded by a piece of the ER membrane, which eventually buds from the membrane surface to form ___ vesicles
transport
Transport vesicles move toward the entry face of the __
Golgi complex
Fusion of several transport vesicles creates the entry face of the Golgi complex, and releases proteins into its ___
space (lumen)
Proteins move from the entry face into one or more _ cisternae
medial
Enzymes in the medial cisternae modify the proteins to form glycoproteins, glycolipids, and ___
lipoproteins
Transfer vesicles that bud from the edges of the cisternae move specific enzymes back toward the entry face of the Golgi complex, and move partially modified proteins toward the ___
exit face
Within the exit face cisterna, the protein products are further ___, and are sorted and packaged
modified
Some of the processed proteins leaving the exit face of the Golgi complex are stored in ___
secretory vesicles
Certain pancreatic cells release insulin by delivering proteins to the plasma membrane from _____, where they are discharged by exocytosis into the extracellular fluid
secretory vesicles
Lysosomes are vesicles that form from the Golgi complex that contain _ when fusing during endocytosis
enzymes
Enzymes work best at a/n _ pH, due to its imported hydrogen ions
acidic
The process by which entire worn-out organelles are digested is called _
autophagy (= self-eating)
The lysosomal interior has a pH of 5, which is 100 times more acidic than the pH of the cytosol (ph _)
7
Acrosomal reaction is used when the head of a sperm cell ____ that aid its penetration of the oocyte by dissolving its protective coating
releases lysosomal enzymes
Similar to strucgture to lysosomes are _, called microbodies, containe several oxidases, enzymes that can oxidize various organic substances
peroxisomes
Peroxisomes oxidize various organic substances such as _, which is why peroxisomes are very abundant in the liver
alcohol
_ provide continuous destruction of unneeded, damaged, or faulty proteins
proteasomes
_, Tiny barrel-shaped structures consisting of four stacked rings of proteins around a central core, serve to provide continuous destruction of unneeded, damaged, or faulty proteins
proteasome
Proteasomes breakdown proteins into small peptides, by its enzymes (proteases), and other ones break down the peptides into _, which can be recycled into new proteins
amino acids
Clumps of misfolded proteins accumulate in brain cells of people with Parkinson’s disease and Alzheimer’s disease. This is like the failure of _ to degrade ABNORMAL proteins
proteasomes
_ serve to:
- digest substances that enter a cell via endocytosis and transport final products of digestion into cytosol;
- carry out autophagy, the digestion of worn-out organelles
- implement autolysis, the digestion of an entire cell, and
- accomplish extracellular digestion
lysosomes
An example of a disorder caused by faulty or absent lysosomal enzymes is _____disease
Tay-Sachs disease
Tay-Sachs Disease is an inherited condition characterized by the absence of a single _ enzyme called Hex A, which typically breaks down a glycolipid that is prevalent in nerve cells, an excess of which causes nerve cells to function less efficiently
lysosomal
They provide structure for the body, take in nutrients from food, convert those nutrients into energy, and carry out specialized functions. Cells also contain the body’s hereditary material and can make copies of themselves. Cells have many parts, each with a different function.
What are the functions of a cell?
How do cells know what to do?
In many ways, the fate of cells mimics the fate of humans. As infants, we all have the potential to become firefighters, teachers, ballerinas or CEOs. But somewhere along the line, life events begin limiting our options. As adults, few of us could backtrack to become art historians after a life spent in computer science classes.
Cells suffer a similar fate. The earliest cells of the human embryo – the so-called stem cells – can go on to form any cell type in the body. But as the cell develops, its DNA accumulates molecular changes that educate the cell about its eventual role. A chunk of adult muscle, no matter how healthy, simply can’t fill in for an ailing liver.
This sealing of fates has long stymied researchers trying to clone new embryos from adult animal cells. Rudolph Jaenisch, MD, biology professor at MIT and faculty member at the Whitehead Institute for Biomedical Research in Cambridge, Mass., has led efforts to understand how the cloning process sporadically lures adult cells to backtrack into their earlier, less-educated state..
