Chapter 3 : Cell Form & Function Flashcards
The Modern Cell Theory
1 - All living organisms are composed of cells.
#2 - The cell is the structural organization of all organisms
(unicellular and multicellular life forms).
#3 - All cells come from preexisting cells (not from nonliving matter)
All life can trace their ancestry to the
same original cells
There are about _ different types of cells in the human body with many different shapes
200
Human cell size
15 micrometers
Red blood cell (RBC) cell size
7.5 µm
There are an estimated ____ cells in human body
50 trillion
Cell volume increases faster than the cells’ surface area
Therefore,
it is the lack of surface area that limits the size
of a cell as it enlarges.
1 micron
1 x 10 (to the 6th power) meters = 0.000001 meters
Factors affecting diffusion rate include:
temperature, molecular weight, steepness of concentrated gradient, membrane surface area, membrane permeability.
Osmosis
the diffusion of water across a
“semi-permeable” membrane
Osmosis ___ require a semi-permeable membrane. Diffusion ____ require a semi-permeable membrane.
does; does not
osmotic pressure
The increase in hydrostatic pressure that stops osmosis
Osmolarity
number of osmoles of solute per liter of solution
osmole
One osmole equals a specific number of particles disolved in water
Osmolality
number of osmoles of solute per kilogram of water
blood plasma has how many milli-osmoles per liter?
300 mOsm/L
What is Tonicity? What does does it depend on?
the ability of the solution around the cell to affect the fluid
volume and pressure of a cell
depends on concentration and permeability of solute
Hypotonic solution
cells absorb water, swell and may burst (lyse)
Hypertonic solution
cells lose water + shrivel (crenate)
Isotonic solution
cause no changes in cell volume or cell shape
What is filtration and what is its nickname?
water molecules and extremely
small solutes are forced to move
through a selectively permeable
membrane
Reverse osmosis
Aquaporins
channels formed by proteins in plasma membrane specialized for passage of water
Cells can increase the rate of osmosis by?
installing more aquaporins
The Intracellular Fluid (ICF), which makes up __% of the bodies fluid, consist of what parts of the cell?
60%
Cytoplasm and Nucleoplasm
Cytoplasm
between plasma membrane and
nuclear membrane
Nucleoplasm
fluid inside nucleus
The Extracellular fluid (ECF), the fluid outside
of the cell, makes up __% of the bodies fluids and consists of what two compartments?
40%
Interstitial Fluid and Vascular Fluid
Interstitial Fluid
Fluid between cells
Vascular Fluid
Fluid inside blood vessels
plasma membrane
is an “active structure”
are selective permeability (know this ///
best description)
__% of molecules in plasma membrane are __. __% of these lipids are __
98% ; lipids ; 75% ; phospholipids
What are the components of the plasma membrane chemical structure?
Phospholipids, cholesterol, glycolipids, protein, and glycoproteins.
Cholesterol makes up how much percent of the membranes lipids? Does what to phospholipids and how? at normal temperatures make the membrane what? and form what in phospholipid bilayer?
– 20% of the membrane lipids
– holds phospholipids still // cholesterol’s -OH units link to fatty
acids
– at normal temperature makes membrane stronger and stiffen
membrane
– form “rafts” within phospholipid bilayer
Glycolipids make up how much percent of membrane lipids? Glycolipids are?
– 5% of the membrane lipids
– phospholipids with short carbohydrate chains on extracellular
face
– contributes to glycocalyx
Proteins and Glycoproteins
Membrane proteins
– 2% of the molecules in plasma membrane
– 50% of its weight
Transmembrane proteins (Integral proteins)
– pass through membrane
– have hydrophilic regions in contact with
cytoplasm and extracellular fluid
– have hydrophobic regions that pass back and
forth through the lipid of the membrane
– most are glycoproteins
– can drift about freely in phospholipid film
– Other transmembrane protein anchored to
cytoskeleton
Most transmembrane proteins are ____
glycoproteins
Peripheral proteins are what kind of molecules? adhere to what? are usually tethered to what? what may bind to peripheral proteins?ww
– actin molecules
– adhere to the intracellar face of the membrane
– usually tethered to the cytoskeleton
– Integral proteins may bond to peripheral
proteins
Receptor membrane proteins
A receptor that binds to chemical messengers such as hormones sent by other cells
Enzyme membrane protein
An enzyme that breaks down a chemical messenger and terminates its effect
Ion Channel membrane protein
A channel protein that is constantly open and allows ions to pass into and out of the cell
Gated ion channel
A gated channel that opens and closes to allow ions through only at certain times
Cell-identity marker membrane protein
A glycoprotein acting as a cell identity marker distinguishing the body’s own cells from foreign cells
Cell-adhesion molecule (CAM) membrane protein
A cell-adhesion molecule (CAM) that binds one cell to another
Uniport
carries only one solute at a time
Symport
carries 2 or more solutes simultaneously in same
direction (cotransport)
Antiport
carries 2 or more solutes in opposite directions
(counter transport)
What is the most important antiport in human physiology?
the sodium-potassium ATP-ase pump
Sodium-potassium ATP-ase pump
brings in two K+ and removes three Na+ from cell’s cytoplasm
active – uses ATP – pumps both ions against their concentration gradient
every cell in your body has this pump!
Glycoproteins and glycolipids contribute to the
formation of the
glycocalyx
glycocalyx
carbohydrates on outer surface of the cell
carbohydrate coating on the cells surface
acts like a cell’s ‘identification tag’
“sugar” coating on cells
Glycocalyx are sugars that enable our immune system to do what?
identify our cells (“self”) from foreign cells
(non-self cells)
What are the two forms of
movement across the plasma membrane?
Passive process and active process
Does passive process move solutes up or down concentration gradient? Does passive process require energy? In passive process, which molecules diffuse across the membrane and which use channels, hydrophobic or hydrophilic molecules?
Down ; no energy required ; Hydrophobic molecules diffuse. Hydrophillic molecules must use a channel
Does active process move solutes up or down concentration gradient? Does passive process require energy? Does active process require a carrier?
up ; requires energy in the form of ATP ; require a carrier
carrier-mediated transport
solute through a membranedown its concentration gradient (diffusion!)
does not consume ATP
Regulated Facilitated Diffusion
“Gates” are opened and closed by using one of these three
stimuli: Ligands, Voltage, or Mechanical
What kind of energy is used in secondary active transport?
Energy stored in the form of an ionic concentration gradient
Pumps
Carrier proteins
the most important one being the sodium and potassium pump
Sodium-potassium “ATP-ase” Pump
each pump cycle consumes one ATP
which is used to moves three Na+
ions out of the cell while moving two
K+ ions into the cell
half of our daily calories are
consumed each day to power the
Na+ - K+ ATP pump
70% of the energy consumed by
brain // due to high level of action
potentials created by neurons!!
Functions of Na+ - K+ ATP Pump
Secondary active transport system // glucose co-transport
Transport Maximum (Tm)
As the solute concentration rises, the rate of
transport rises until carriers are saturated!
(Tina’s note: These transporters can only move so many things at a time
Transport Vesicles
Cells Use Transport Vesicles to Move Large Particles or globs of
liquids (too large to pass through a channel) Across the Plasma Membrane
Endocytosis
enter cell
exocytosis
exit cell
What are the three types of endocytosis?
receptor mediated endocytosis, phagocytosis, bulk-phase endocytosis
Phagocytosis
is an example of endocytosis used by WBC
Bulk-phase Endocytosis
AKA: pinocytosis
What are the three cytoplasm components:
Cytosol, Cytoskeleton, Organelles
Cytosol (intracellualr fluid)
75 – 90% fluid // site of
many of the chemical reactions of the cell
Cytoskeleton
Collection of protein filaments and cylinders constructed from
protein subunits
Organelles
specialized structures / some organelles surrounded by unit membranes so as to isolates cellular chemical reactions // other organelles are not surrounded by unit membranes
What is the function of a cytoskeleton?
– determines shape of cell
– lends structural support
– organizes its contents
– directs movement of substances through the cell // cytoskeleton functions like a highway for transporting vesicles
– contributes to the movements of cell as a whole
Three types of cytoskeletons:
microfilaments, intermediate filaments, and
microtubules (Be able to identify them by a photo. Slide 65)
Integrin (transmembrane proteins)
Allows Cytoskeleton to Connected to Extracellular Structures
A microtubule is a cylinder of __ parallel strands called ________
13 : protofilaments
protofilaments are long chains of globular proteins called
tubulin
Microtubules radiate from where and hold what in place?
microtubules radiate from centrosome and hold organelles in place
motor proteins
‘walk’ along microtubules carrying organelles and other
macromolecules to specific locations in the cell
Are microtubules permanent structures?
no
tubulin ___and ____
assembles ; disassembles
Moment by moment microtubules may change. This action also allows some cells to ____
“move”
Nucleus
the “hard drive” of your computer
How large is the nucleus? What is the percentage of the nucleus volume in the cell?
5 um (micrometer) in diameter ; 40%
most cells have ___ nucleus. Some cell types are ____
one ; multinucleated
Nuclear envelope
two unit membranes surround nucleus
nuclear pores
Perforate nuclear envelope and are formed by rings of protein
- regulate molecular traffic through envelope
- hold two unit membranes together
- provides points of attachment and organization for
chromatin - plays role in regulation of the “cell cycle”
Nucleoplasm
the cytoplasm of the nucleus
supports nuclear envelope and pores // provides points
of attachment and organization for chromatin
Nucleoplasm is a web of ______ _______ and ___
protein filaments ; DNA
chromatin
(thread-like matter) composed of DNA and
protein
nucleoli
one or more dark masses inside nucleus
where ribosomes are produced
centriole
are the “birthing station” for microtubules
a short cylindrical assembly of microtubules arranged in nine groups of three microtubules each
centresome
in most cells two centrioles are located at one pole
on the exterior surface of the nucleus in a region
called the centresome
two centrioles lie _____ to each other // one
funtion is to play key role in ___ another
funtion is to produce _____ _____
perpendicular to each other ; cell division ; cytoskeleton’s microtubules
What forms the basal body of cilia and flagella?
centrioles! YAY!
Single centriole play role in structure
and function of both cilia and flagella
basal bodies originate in ___ ____ ____ and migrates to
plasma membrane
centriolar organizing center
___ microtubules of each triplet elongate to form the nine pairs of peripheral microtubules of the ____
two ; axoneme
cilium reaches full length in less than ______
one hour
Cilia
Hairlike processes
Single non-motile cilia are also called? Are found on? function as? Sensory?
A single cilia is called a “primary cilium”.
They are found on all cells in the body.
Function as an “antenna’ for monitoring extracellular conditions. Sensory in inner ear, retina, nasal cavity, and kidney
Multiple motile cilia function
sweep substances across surface in same
direction
Axoneme
core of cilia that is the structural basis for ciliary movement
The axoneme has a 9+2 structure of microtubules
– 9 pairs form basal body inside the cell
membrane // anchors cilium
– dynein arms “crawls” up adjacent
microtubule bending the cilia // uses
energy from ATP
Saline Layer
____ pumps pump __ into ECF
____ and ___ follows
Layer above plasma membrane that cilia “whip” in
chloride ; Cl-
Na+ ; H20
Cystic fibrosis
hereditary disease in which cells make chloride pumps, but fail to install them in the plasma membrane
chloride pumps fail to create adequate
saline layer on cell surface
thick mucus plugs pancreatic ducts and
respiratory tract
– inadequate digestion of nutrients and
absorption of oxygen
– chronic respiratory infections
– life expectancy of 30
Flagella
whiplike structure with axoneme identical to cilium
movement is more undulating, snakelike
The only functional flagellum is
the tail of the male’s sperm
Microvilli size
1-2 um (micrometers)
Microvilli function
increase cell’s surface area
specialized in absorption
gives 15 – 40 times more absorptive surface area
Microvilli “act like a sponge”
on some cells, microvilli are very dense and appear as a
fringe ______
“brush border”
What is “milking action of actin”
actin filaments shorten microvilli, pushing absorbed contents down into cell
Ribosomes
“protein factories”
complex of small granules of protein and RNA
they ‘read’ coded genetic messages (messenger RNA) and
assemble amino acids into proteins specified by the code
Where are ribosomes found?
found in nucleoli, in cytosol, on outer surfaces of rough
ER, and in nuclear envelope
“Two type of ribosomes // make protein either for _____ or ____”
internal use ; export outside cell
endoplasmic reticulum
system of interconnected channels called cisternae enclosed by unit membrane
cisternae
system of interconnected channels on ER enclosed by unit membrane
Rough endoplasmic reticulum
-produces the phospholipids and proteins of the
plasma membrane
-synthesizes proteins that are packaged in other
-organelles or secreted from cell
have cisternae connected by perpendicular bridges
Smooth endoplasmic reticulum
lack ribosomes
cisternae more tubular and branching
synthesizes steroids and other lipids
detoxifies alcohol and other drugs
manufactures all membranes of the cell
Golgi Complex is a small system of cisternae that synthesize
______ and put the finishing touches on ____ and
_______ _______
carbohydrates ; protein ; glycoprotein synthesis
Golgi Complex receives newly synthesized proteins from ___
rough ER
sorts them, cuts and splices some of them, adds
carbohydrate moieties to some, and packages the protein
into membrane-bound Golgi vesicles
Think of it as the post office of the cell!
Lysosomes
package of enzymes bound by a single unit membrane //
extremely variable in shape
They destroy cells that are considered waste
intracellular hydrolytic digestion of proteins, nucleic acids, complex carbohydrates, phospholipids, and other substances
Lysosomes fuse with vesicles from ____ to form ____ . They
___ content of phagosomes
endocytosis ; phagosome ; digest
Membrane pumps move ___ into lysosomes because enzymes work best in ___ environment
protons ; acid
autophagy
digest and dispose of worn out mitochondria and other
organelles
autolysis
‘cell suicide’ – some cells are meant to do a certain job and
then destroy themselves
Pertaining to lysosomes, digested content in ___ may also fuse with ___ and release digested content into ______.
phagosome ; plasma membrane ; interstitial space
Peroxisomes
resemble lysosomes but contain different
enzymes /// used to destroy toxic molecules
How do peroxisomes oxidize organic molecules?
Use molecular oxygen to oxidize organic molecules – take
hydrogen off molecules (creates free radicals like hydrogen
peroxide)
Peroxisomes neutralize and detoxify what?
neutralize free radicals, detoxify alcohol, other drugs, and a
variety of blood-borne toxins
Peroxisomes are present in all cells, but abundant in
liver and kidney
Proteasomes
Digest old or no longer needed cytoplasmic proteins
Tubular structure with no unit membranes
Proteasomes turn protein into _____
amino acids which are reused to make new protein
Proteins to be digested by proteasome must be “tagged” by
______
ubiquitin
Proteasomes are extremely ____ organelles
small
Proteins enter interior of the tubular proteasome and ____ are broken
peptide bonds
Proteasomes are also found in ____
nucleoplasm
Mitochondrion
“Powerhouses” of the cell
organelles specialized for synthesizing ATP
energy is extracted from organic molecules
and transferred to ATP
Mitochondria come in a variety of shapes and are surrounded by a double unit membrane. What are the parts of this double unit membrane?
– inner membrane has folds called cristae
– spaces between cristae are called matrix
Mitochondria have their “own”
genetic information.
All mitochondria are “maternal”
meaning they come from the
egg. (sperm do not contribute
any mitochondria to the zygote)
Mitochondria’s DNA is a
“circular” chromosome” //
prokaryote architecture.
At one time in history
mitochondria lived as an
independent self sustaining
organism. Much like the bacteria
of today.
