Chapter 4 Flashcards
Cytology is the
study of cells
The different types of microscopes are _(2)
1) Light microscope (what we use in class)
2) Electron microscope
a) Transmission electron miscroscope (TEM) (directs electrons through thin-cut sections)
b) Scanning electron microscope (SEM) (electons through surface of specimen…this is more powerful than TEM)
Cells vary greatly in ___ and _
Size (7-120 picometer?)
Shape (spherical, tubelike, column like, cylindrical, etc.)
The plasma membrane
1)forms outer limiting barrier (separates internal contents from external environment)
What are some modified extensions of the plasma membrane _(3)
Cilia
flagellum
microvilli
The nucleus is/has _(3)
1)largest strucure in the cell (enclosed by a nuclear envelope)
2)contains genetic material (DNA); also contains a nucleolus
3)nucleoplasm(inner fluid)
The cytoplasm is/has
1)the cellular contents between the plasma membrane and the nucleus
2)includes: cytosol, organelles, and inclusions
What is cytosol _(2)
1) The intracellular fluid that is viscous and has a high water content
2) It contains dissolved macromolecules and ions
Organelles are _
1)little complex organs within cells
2)Unique shapes and functions
The two types of organelles are _
1)membrane-bound organelles
2)non-membrane-bound organelles
Membrane-bound organelles are _(3)
1) enclosed by a membrane
2) Separates contents from cytosol
3) Includes endoplasmic reticulum, Golgi apparatus, lysosomes, peroxisomes, mitochondria
Non-membrane-bound organelles are _
1)not enclosed within a membrane
2)composed of protein
3) includes ribosomes, cytoskeleton, centrosome, proteasomes
Cells perform general functions _
1) Maintain integrity and shape of cell(dep. on plasma membrane and internal contents)
2)obtain nutrients and form chemical building blocks (harvest energy for survival)
3)Dispose of wastes (avoid accumulation that could disrupt cellular activities
Note: some are capable of cell division(make more cells of the same type)…help maintain tissue by providing cells for new growth and replacing dead cells
The Plasma membrane is a _(4)
1) fluid mixture composed of equal parts (lipid and protein by weight)
2)regulates movement of most substances in and out of cell
3)contains several different types of lipids like:
phospholipids, cholesterol, glycolipids
4)establishes and maintains electrochemical gradient
What are the different types of lipids within the plasma membrane _(3)
1)Phospholipids,
2)cholesterol
3)glycolipids
What are the two types of membrane proteins _
1) Integral
2)Peripheral(they don’t go all the way across)
Membrane proteins are/do _(3)
1) half of plasma membrane by weight
2)float and move in fluid bilayer
3) performs most of the membrane functions
What are the six categories of functional proteins _
1)transport proteins (regulate the movement of substances across the membrane)
2)Cell surface receptors (bind molecules called ligands
3) Identity markers (communicate to other cells that they belong to the body…they also distinguish healthy cells from cells to be destroyed
4)enzymes (may be attached to either internal or external surface of a cell…catalyze chemical reactions)
5)anchoring sites (secure cytoskeleton to plasma membrane
6)cell-adhesion proteins(perform cell-to-cell attachments
Membrane transport is _(1)
The process of obtaining and eliminating substance across the plasma membrane
The two types of membrane transport are _
1)Passive processes(don’t require energy…dependent on substances moving down concentration gradient)
2)Active processes(require energy…substances must be moved up its concentration gradient…membrane bound vesicle must be released(vesicular transport)
What are the two types of passive transport _
1)Diffusion
2)Osmosis
Diffusion is _(2)
1)the net movement of ions or molecules from area of greater concentration to area of lesser concentration (down the concentration. gradient)
2)its influenced by temperature(increase temp. and you increase the kinetic energy and rate of diffusion)
Simple diffusion _(4)
1) molecules that move unassisted between phospholipid molecules
2) small and nonpolar solutes
3)not regulated by plasma membrane
4)movement dependent on concentration gradient(moves as long as gradient exists
Facilitated diffusion _
1)transport process for small charged or polar solute(requires assistance from plasma membrane proteins
What are the two typees of facilitated diffusion _
1)Channel-mediated diffusion
2)Carrier-mediated diffusion
Channel-mediated diffusion is _
1)movement of small ions through water-filled protein channels
2)small polar molecules assisted across membrrane by carrier protein
3)releases substancese on other side of membrane(# of channels and carriers determine the max rate of substance transport )
4)move substances down their gradient
A uniporter is _
a carrier transporting only one substance
Osmosis is _
Movement of water, not solutes( Passive movement of water through semipermeable membrane)
two ways water crosses membrane _
1)Slips between molecules of phospholipid bilayer
2) Moves through integral protein water channels—aquaporins
Hypo means _
low
Hyper means _
high
Two types of solutes _
1)Permeable solutes
* Pass through bilayer
* For example, small and nonpolar solutes such as oxygen, carbon dioxide, urea
2)Nonpermeable solutes
* Prevented from passing through bilayer
* For example, charged, polar, or large solutes such as ions, glucose, protein
Osmotic pressure is _
1) Pressure exerted by movement of
water across semipermeable
membrane
2) Due to difference in solution
concentration
3) Steeper gradient, more water
moved by osmosis and greater
osmotic pressure
Hydrostatic pressure is _
pressure exerted by a fluid on the inside
wall of its container
Osmosis helps the cell _
gains or loses water with osmosis
along with a change in cell volume and
osmotic pressure
Tonicity is _
The ability of a solution to change
the volume or pressure of a cell by
osmosis
Terms that describe relative
concentration of solutions _(3)
Isotonic
Hypotonic
Hypertonic
Active transport _
1)Movement of a solute against its
concentration gradient (that is, from lower
to higher concentration)
2)Maintains gradient between cell and
interstitial fluid
3)Source of energy determines whether
Movement is primary or secondary
Primary active transport _
Uses energy directly from
breakdown of ATP
Phosphorylation of carrier occurs _
1) Breakdown of ATP results in phosphate
group added to transport protein
2) Changes protein’s shape and results in
movement of substance across the
membrane
Ion pumps
Cellular protein pumps that
move ions across membrane
* Maintain internal
concentrations of ions
Sodium potassium pump _
moves one type of ion into cell against gradient while moving another. type of ion out of cell against gradient
Secondary active transport _. Two subtypes _
moves substance against concentration gradient
symport
antiport
Vesicular transport(bulk transport) _.
Involves energy input to
transport large substances
across the plasma membrane
by a vesicle
* Membrane-bounded sac filled with
materials
The two types of veesicular transport are _
exocytosis
endocytosis
Exocytosis _
Large substances secreted from cell
* Macromolecules too large to be moved
across membrane
* Material packed within intracellular
transport vehicles
* Vesicle and plasma membrane fusion
* Requires ATP
* Contents released to outside of cell
following fusion
Endocytosis _
Cellular uptake of large substances
from external environment
* Steps of endocytosis are similar to
exocytosis, but in reverse
* Pocket (invagination) forms, pinches off
to form vesicle
* Used for
* Uptake of materials for digestion
* Retrieval of membrane regions from
exocytosis
* Regulation of membrane protein
composition to alter cellular processes
Three types of endocytosis:
phagocytosis (cellular eating)
pinocytosis (cellular drinking)
receptor-mediated endocytosis(Uses receptors on plasma membrane to bind molecules within interstitial fluid and bring the molecules into cell
* Enables the cell to obtain bulk quantities of
substance)
The role of K+
Most important determinant in specific value of RMP
* K+ moves down steep concentration gradient through leak
channels from cytosol to interstitial fluid
* Negatively charged proteins remain inside cell
* Electrochemical gradient
* Positive charge outside repels movement of K+ out
* Negative charge on inside attracts K+ inward
* K+ moves until equilibrium is reached
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The role of Na+
Na+ diffuses into cells from interstitial fluid to cytosol
simultaneous to the loss of K+
* Enters through Na+ leak channels
* Down concentration gradient
* Pulled by electrical gradient
* Leak channels prevent as much Na into the neuron a K+
out
* Inside becomes more positive
Maintaining an RMP
Na/K pumps significant
* Maintains K+ and Na+ gradients following their diffusion
* Na+ pumped out
* K+ pumped in
* Opposite directions
* Against concentration gradient
Most cell communication occurs through ligands
Molecules that bind with macromolecules
* Neurotransmitters from nerve cells and hormones from
endocrine cells
* Important for controlling growth, reproduction, and other
cellular processes
3 types of receptors that bind ligands:
Channel-linked receptors
* Enzymatic receptors
* G protein-coupled receptors
Enzymatic Receptors
Protein kinase
enzymes
* Activated to
phosphorylate other
enzymes within the cell
* Provides mechanism
for altering enzymatic
activity
Endoplasmic Reticulum (ER)
Extensive interconnected membrane network
* Varies in shape, but one continuous lumen
* Extends from nuclear envelope to plasma
membrane
* Composes about half of membrane within cell
* Point of attachment for ribosomes
* With ribosomes—rough ER
* Without ribosomes—smooth ER
Rough ER _
Protein production by ribosomes, inserted
into ER
* Original structure of protein changed
* Transported out in enclosed membrane
sacs
* Transport vesicles shuttle proteins from rough
ER lumen to Golgi apparatus
Smooth ER _(4)
Diverse metabolic processes vary by cell
* Functions
* Synthesis, transport, and storage of lipids
* Carbohydrate metabolism
* Detoxification of drugs and poisons
Golgi apparatus
Composed of cisternae, elongated saclike
membranous structures
* Exhibits polarity
* Cis-face
* Proximal to ER
* Trans-face
* Distal from ER
* Functions: modification, packaging, and sorting
of proteins
* Formation of secretory vesicles
* Some vesicles become part of plasma membrane
* Others release contents outside cell
Lysosomes
Small, membranous
sacs
* Contain digestive
enzymes formed by
Golgi
* Participate in digestion
of unneeded
substances
* Digest contents of
endocytosed vesicles
Peroxisomes
Membrane-enclosed sacs,
smaller than lysosomes
Pinched off vesicles from
rough ER
Proteins are incorporated to
serve as their enzymes
Metabolic functions include
* Role in chemical
digestion
* Beta oxidation
* Lipid synthesis
Endomembrane System _
Extensive array of membrane-bound structures
* Includes ER, Golgi apparatus, vesicles, lysosomes,
peroxisomes
* Includes plasma membrane and nuclear envelope
* Connected directly or through vesicles moving between
them
* Provides means of transporting substances within cells
Mitochondria
Oblong shaped
organelles with double
membrane
* Aerobic cellular
respiration
* Complete digestion of
fuel molecules to
synthesize ATP
* “Powerhouses” of cell
