Chapter 3 Flashcards
(46 cards)
How many types of cells are there in the human body?
About 200 types of cells
What type of cell is thin and flat with the nucleus creating bulge?
Squamous
What type of cell is irregularly angular shaped with 4 or more sides?
Polygonal
What type of cell is starlike shape?
Stellate
What type of cell is squarish and about as tall as they are wide?
Cuboidal
What type of cell is taller than wide?
Columnar
What type of cell is round to oval shaped?
Spheroid to Ovoid
What type of cell is disc-shaped?
Discoid
What type of cell is thick in middle, tapered toward the ends?
Fusiform
What type of cell is threadlike shaped?
Fibrous
What part of the phospholipids in the plasma membrane are hydrophilic, hydrophobic? How do the phospholipids behave in the plasma membrane? Why is this behavior important?
Hydrophilic heads
Hydrophobic tails
- drift laterally from place to place
– movement keeps membrane fluid
What percent of membrane lipids are phospholipids, cholesterol, and glycolipids? What percent of the plasma membrane is lipids? What is the rest made of?
Phospholipids - 75%
Cholesterol - 20%
Glycolipids - 5%
Total Lipids - 98% (Protein is 2%, but accounts for 50% of the weight)
What happens when a cell is placed in a hypotonic solution?
A hypotonic has a lower concentration of nonpermeating solutes than intracellular fluid (ICF)
Hypotonic solution has a high water concentration
cells absorb water, swell and may burst (lyse)
What happens when a cell is placed in a hypertonic solution?
- the ECF (extracellular fluid) has a higher concentration of nonpermeating solutes (i.e., low water concentration) than the ICF (intracellular fluid).
- cells lose water + shrivel (crenate)
What is the purpose of cholesterol in the plasma membrane?
holds phospholipids still and can stiffen membrane
What are glycolipids and what is the purpose of glycolipids in the plasma membrane?
- phospholipids with short carbohydrate chains on extracellular face
– contributes to glycocalyx – carbohydrate coating on the
cells surface, fuzzy coating
What is Glycocalyx? What is its functions?
Unique fuzzy coat external to the plasma membrane
– carbohydrate moieties of membrane glycoproteins and glycolipids
– unique in everyone, but identical twins
• Functions (see Table 3.2)
– protection - cell adhesion
– immunity to infection - fertilization
– defense against cancer - embryonic development
– transplant compatibility
In chemistry, a moiety refers to a distinct portion or part of a molecule.
What is the function of the plasma membrane?
Prevents escape of cell contents; regulates exchange of materials between cytoplasm and extracellular fluid; involved in intercellular communication
What is the function of the Microvilli?
Increase absorptive surface area; widespread sensory roles
(hearing, equilibrium, taste)
What are the two types of membrane proteins? Locations? Characteristics?
Transmembrane 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
– some anchored to cytoskeleton
• Peripheral proteins
– adhere to one face of the membrane
– usually tethered to the cytoskeleton
What are the six membrane protein functions?
receptors, second-messenger systems,
enzymes, ion channels, carriers, cell-identity markers, cell-adhesion molecules
(a) Receptor
A receptor that
binds to chemical
messengers such
as hormones sent
by other cells
(b) Enzyme
An enzyme that
breaks down
a chemical
messenger and
terminates its
effect
(c) Ion Channel
A channel protein
that is constantly
open and allows
ions to pass
into and out of
the cell
(d) Gated ion channel
A gated channel
that opens and
closes to allow
ions through
only at certain
times
(e) Cell-identity marker
A glycoprotein
acting as a cell-
identity marker
distinguishing the
body’s own cells
from foreign cells
(f) Cell-adhesion
molecule (CAM)
A cell-adhesion
molecule (CAM)
that binds one
cell to another
Tell me what you know of mitochondrial DNA?
mitochondrial ribosomes more like bacterial ribosomes
– has its own mtDNA
• small circular molecule resembling bacterial DNA
• replicates independently of nuclear DNA
– when a sperm fertilizes the egg, any mitochondria introduced by the
sperm are usually destroyed, and only those provided by the egg are
passed on to the developing embryo
• mitochondrial DNA is almost exclusively inherited through the mother
– mutates more readily than nuclear DNA
• no mechanism for DNA repair
• produces rare hereditary diseases
• mitochondrial myopathy , mitochondrial encephalomyopathy,
and others
How does the Sodium-Potassium pump work?
SOPIA-3,2,1
3 Sodium Out
2 Potassium In
1 ATP
Active Transport
keeps the K+ concentration higher in the ICF and the Na+ concentration higher in the ECF
• necessary because Na+ and K+
constantly leak through membrane
– half of daily calories utilized for
Na+ - K+ pump
What factors affect diffusion rates through a membrane?
– temperature - higher temp., higher motion of particles
– molecular weight - larger molecules move slower
– steepness of concentrated gradient - greater difference, greater rate
– membrane surface area - higher area, higher rate
– membrane permeability - high permeability, high rate
