Lesson 1 - chapter 2 - cell Flashcards
2 major parts of cell
nucleus
cytoplasm
nucleus is separated from the cytoplasm
by a
nuclear membrane
cytoplasm is separated
from the surrounding fluids by a
cell membrane, also
called the plasma membrane.
different substances that make up the cell
protoplasm
Protoplasm is composed
mainly of five basic substances
water 70-85%
electrolytes,
proteins 10-20%
lipids, and
carbohydrates.
principal fluid medium of the cell
present in most cells, except for fat cells,
70-85%
Many cellular chemicals are dissolved
water
ions/electrolytes:
K+ potassium,
MG+2 magnesium,
PO4 -3 phosphate,
SO4 -2 sulfate,
CHO3- bicarbonate
smaller quantities of sodium, chloride, and calcium
provide inorganic chemicals for cellular reactions and also are necessary for operation of some of the
cellular control mechanisms
IONS
2nd most abundant substances
in most cells are
proteins
present in the cell mainly in
the form of long filaments that are polymers of many
individual protein molecules.
A prominent use of such intracellular filaments is to form microtubules that provide
the “cytoskeletons” of such cellular organelles as cilia,
nerve axons, the mitotic spindles of cells undergoing
mitosis, and a tangled mass of thin filamentous tubules that hold the parts of the cytoplasm and nucleoplasm together in their respective compartments.
structural proteins
mainly the enzymes of the cell and, in contrast to the
fibrillar proteins, are often mobile in the cell fluid.
functional proteins
are found outside the cell, especially in the collagen and elastin fibers of connective tissue and in blood vessel walls, tendons, ligaments, and so forth.
Fibrillar proteins
soluble in fat solvents
lipids
Especially important lipids which together constitute only about 2% of the total cell mass
phospholipids and cholesterol
triglycerides, also called neutral fat
fat cells, triglycerides often account for
as much as ________ of the cell mass
95%
The fat stored in
these cells represents the body’s main storehouse of
energy-giving nutrients that can later be used to provide
energy wherever in the body it is needed
lipids
1% of total cell mass,
3% in muscles,
6% in liver): glycogen
carbohydrates
which is an insoluble polymer of glucose that can
be depolymerized and used rapidly to supply the cells’ energy needs.
glycogen
MEMBRANOUS STRUCTURES
OF THE CELL:
cell membrane,
nuclear membrane,
membrane of the endoplasmic reticulum,
membranes of the mitochondria, lysosomes, and Golgi apparatus
_________ in the membranes provide a barrier that
impedes movement of water and water-soluble substances from one cell compartment to another because water is not soluble in lipids
lipids
molecules providing specialized pathways, often organized into actual pores, for passage of specific substances through the membrane
protein
proteins that catalyze a multitude of
different chemical reactions, discussed here and in subsequent chapters
enzymes
cell membrane (also called the plasma membrane)
envelops the cell and is a thin, pliable, elastic structure
only 7.5 to 10 nanometers thick.
cell membrane (also called the plasma membrane)
approximate composition or cell membrane:
proteins, 55%
phospholipids, 25%
cholesterol, 13%
other lipids, 4% and
carbohydrates, 3%
basic lipid bilayer is composed of three main types
of lipids:
phospholipids,
sphingolipids, and
cholesterol
most abundant, has 2 sides
Phospholipids
(fatty acid portion) hydrophobic and
soluble only in fats (e.g. O2, CO2, alcohol);
faces each other
Outer side of phospholipid
(phosphate end) hydrophilic and
soluble in water (e.g. ions, glucose, urea);
faces interstitial fluid & cell cytoplasm
inner side of phospholipid
derived from the amino alcohol
sphingosine, functions to protect from harmful
factors, signal transmission, and adhesion sites for
extracellular proteins
Sphingolipids
Cholesterol - help determine the degree of
permeability of the bilayer to water- soluble
constituents of body fluids. Also controls much of the
fluidity of the membrane as well.
Cholesterol
2 Membrane proteins “glycoproteins”:
○ Integral proteins
○ Peripheral proteins
protrude all the way through the
membrane.
Provide structural channels “pores” that
allow preferential diffusion of some
substances over others
Carrier proteins for transporting substances
that otherwise could not penetrate the lipid
bilayer (e.g. through active transport
Receptors/ second messengers relaying the
signal from the extracellular part of the
receptor to the interior of the cell.
Integral proteins
attached only to one surface and
do not penetrate all the way through; function almost
entirely as enzymes or as controllers of transport of
substances through cell membrane pores
Peripheral proteins
loose carbohydrate (proteoglycans) coat on the outside of the entire surface of the cell
Membrane carbohydrates “glycocalyx”
○ overall negative surface charge that repels other
negatively charged objects
○ attaching cells to one another through glycocalyx
○ act as receptors for binding hormones
○ Some moieties enter into immune reactions
Membrane carbohydrates “glycocalyx”
Cytosol - jelly like fluid portion of the cytoplasm and contains mainly dissolved proteins, electrolytes, and glucose
Cytosol
Dispersed in the cytoplasm are neutral fat globules, glycogen granules, ribosomes, secretory vesicles, and five especially important organelles:
○ Endoplasmic reticulum (ER)
○ Golgi apparatus
○ Mitochondria
○ Lysosomes
○ Peroxisomes
○ a network of tubular structures (cisternae) and flat
vesicular structures in the cytoplasm
○ Manufacture: proteins, carbohydrates, lipids
○ helps process molecules made by the cell and
transports them to their specific destinations
Endoplasmic Reticulum
Attached with minute granular particles
“ribosomes — composed of a mixture of
RNA and proteins; they function to
synthesize new protein molecules in the cell
Rough (Granular) ER + Ribosomes
functions for the synthesis of lipid
substances and for other processes of the
cells promoted by intrareticular enzymes
Smooth (Agranular) ER
○ composed of four or more stacked layers of thin, flat, enclosed vesicles lying near one side of the nucleus
Golgi Apparatus
Function in association with ER — small transport
vesicles/ ER vesicles continually pinch off from the ER
and shortly thereafter fuse with the Golgi apparatus
—> transported substances from ER are processed in
the here to form lysosomes, secretory
vesicles, and other cytoplasmic components
Golgi apparatus
vesicular organelles that form by breaking off from the
Golgi apparatus that provide an intracellular digestive
system to digest the following:
■ damaged celllar structures;
■ food particles ingested by the cell;
■ unwanted matter such (e.g. bacteria)
Lysosomes
lysosomes Uses _________ to splits organic compounds into two or more parts by combining hydrogen from a water molecule with one part of the compound and combining the hydroxyl portion of the water molecule with the other part of the compound — to become highly diffusible (e.g. protein hydrolyzed to form
amino acids)
hydrolytic enzymes
Formed by self-replication (or perhaps by budding off
from the smooth SR)
Peroxisomes
contain oxidases — combining oxygen with hydrogen
ions derived from different intracellular chemicals to
form hydrogen peroxide (H2O2) — which is a highly
oxidizing substance and is used in association with
catalase — to oxidize/ catabolize many substances
that might otherwise be poisonous to the cell
Peroxisomes
formed by the ER — which pinch off to be Golgi
apparatus — Golgi apparatus releases into the
cytoplasm in the form of storage vesicles named
“secretory vesicles/secretory granules”
“secretory vesicles/secretory granules”
store protein proenzymes (enzymes that are not yet
activated) — secreted later through the outer cell
membrane into the pancreatic duct and then into the
duodenum, where they become activated and
perform digestive functions on the food in the
intestinal trac
Secretory Vesicles
○ Powerhouse; self-replicative
○ Mainly for chemical reaction of O2 with 3 types of
foods: glucose (carbo), fatty acid (fats), amino acids
(proteins)
○ 2 Lipid Bilayer protein membranes
■ Outer membrane
■ Inner membrane
Mitochondria
infoldings of the inner
membrane form shelves or tubules
which oxidative enzymes are
attached;
Cristae
the inner cavity of the
mitochondrion is filled with a
_________ that contains large
quantities of dissolved enzymes
necessary for extracting energy
from nutrients
matrix
synthesizes a high-energy substance
called adenosine triphosphate (ATP) — which is then transported out of the mitochondrion and diffuses
throughout the cell to release its own energy — end
products are H2O & CO2
Citric Acid Cycle
○ Rigid and have large numbers of filamentous or
tubular structures, which are composed of fibrillar
proteins synthesized by ribosomes in the cytoplasm
○ Intermediate filaments
○ Microtubules
Cell Cytoskeleton — Filament & Tubular Structures
■ strong ropelike filaments that often work
together with microtubules, providing
strength and support for the fragile tubulin
structures
■ Types: desmin filaments in muscle cells,
neurofilaments in neurons, and keratins in
epithelial cells
Intermediate filaments
■ special type of stiff filament composed of
polymerized tubulin molecules used in all
cells to construct strong tubular structures
■ Makes up the centrioles & mitotic spindles
■ participate in cell division, allows cells to
move, and provides a tracklike system that
directs the movement of organelles in the
cells
Microtubules
○ Control center — sends messages to the cell to grow and mature, replicate, or die
○ Contains large quantities of DNA which comprise
genes — determine the characteristics of the cell’s
proteins, intracellular enzymes and nuclear activities;
also control and promote cell reproduction (mitosis)
Nucleus
● two separate bilayer membranes,
separates the nucleus from the
cytoplasm
● Penetrated with several thousand
nuclear pores
Nuclear membrane/ Nuclear envelope
● simply an accumulation of large
amounts of RNA and proteins of
the types found in ribosomes; not
surrounded by a membrane
● RNA is used in conjunction with
specific proteins to assemble
“mature” ribosomes that play an
essential role in forming proteins
Nucleoli
- involves simple movement through the membrane caused by the random motion of the molecules of the substance.
- Substances move through cell membrane pores or, in the case of lipid-soluble substances, through the lipid matrix of the membrane.
Diffusion
involves actually carrying a substance through the membrane by a physical protein structure that penetrates all the way through the membrane
Active transport
Specialized function of the cell membrane that allows large particles enter the cell:
A. Pinocytosis
B. Phagocytosis
ingestion of small globules of extracellular fluid, forming minute vesicles in the cell cytoplasm
only means whereby most large
macromolecules, such as most proteins, can
enter cells; process also requires the
presence of calcium ions in the extracellular
fluid
Pinocytosis
Uses specialized protein receptors on the
small pits (COATED PICS) on the outer surface
of the cell of the membrane, that are
specific for the type of protein that is to be
absorbed
Pinocytosis
On the inside of the cell membrane beneath
these pits is a latticework of fibrillar protein
called CLATHRIN— which invaginates inward,
and fibrillar proteins surrounding the
invaginating pit cause its borders to close
over the attached proteins, as well as over a
small amount of extracellular fluid
Pinocytosis
invaginated portion of the membrane breaks
away from the surface of the cell, forming a
pinocytotic vesicle inside the cytoplasm of
the cell
Pinocytosis
ingestion of large particles, such as
bacteria, whole cells, or portions of degenerating
tissue
Phagocytosis
Only certain cells have the capability of
phagocytosis—notably, ________ & _____________
tissue macrophages
and some white blood cells
initiated when a particle such as a
bacterium, dead cell, or tissue debris binds
with receptors on the surface of the
phagocyte.
In the case of bacteria, each
bacterium is usually already
attached to a specific antibody
which attaches to the phagocyte
receptors —dragging the
bacterium along with it.
opsonization
Phagocytosis occurs in the following steps:
- The cell membrane receptors attach to the
surface ligands of the particle. - The edges of the membrane around the
points of attachment evaginates outward to
surround the entire particle; then, - Actin and other contractile fibrils in the
cytoplasm surround the phagocytic vesicle
and - The contractile proteins then pinch the stem
of the vesicle so completely that the vesicle
separates from the cell membrane,
digests the Pinocytic and Phagocytic foreign
substances in the cell. These are produced by the Endoplasmic Reticulum, and often globular and enzymatic in function.
Lysosomes
As soon as Pinocytic or Phagocytic vesicles are formed, Lysosomes are attached to vesicles and empty the Digestive Enzymes.
This is now referred to as the _____________, and they have hydrolyzing properties. It will destroy proteins, carbohydrates, lipids, and other substances in the vesicle.
Digestive Vesicle
The products of digestion are often small molecules. ________________ This can diffuse from the membrane of the vesicle and go to the cytoplasm.
Proteins end up being Carbohydrate, Carbohydrates end up being Glucose.
Any undigested substances are left behind in the form of residual body that is excreted through the cell membrane by a reverse endocytosis (___ ), which is basically the opposite
of endocytosis.
exocytosis
responsible for Cytoprotein formation. The
ribosomes synthesize the protein and exclude them to the wall of the ER to Endoplasmic vesicles and tubules, which is now an Endoplasmic Matrix.
Granular ER
processes the substances formed in the ER
(there is post-processing).
performs the compaction and processing of the products of the endoplasmic reticulum, and small and large vesicles would break out from the
golgi apparatus and carry them to secretory substances.
Golgi apparatus
The principal substances from which cells extract energy are:
- Oxygen
- Carbohydrates, fats, and amino acids, which react with oxygen
substances are processed in the golgi complex and form
lysosomes,
secretory vesicles, and other
cytoplasmic components.
Small spherical vesicles surrounded by a membrane that contains digestive enzymes
provide an Intracellular Digestive
System
Lysosomes
is a nucleotide composed of nitrogenous base adenine, the pentose sugar ribose, and three phosphate radicals.
ATP or the adenosine triphosphate
The last 2 phosphate radicals are connected with the remainder through high energy phosphate bonds.
These bonds contain ____________of energy per molecule of ATP under usual conditions the high
energy phosphate bonds are labile so they can be split instantly whenever energy is required.
12,000 calories
_______ combine to form new ATP, which, in this case the entire process actually continues over and over again for the body
ATP and phosphoric acid
So most of the ATP produced in the cell is through mitochondria.
After entering the cell, the glucose is subjected to glycolysis to form by ______________
pyruvic acid
Pyruvic acid as a product of glycolysis also comes from the degradation of carbohydrates, fatty acids, and amino acids, which are eventually all converted to ___________________
Acetyl-CoA
Acetyl-CoA as a compound is formed in the mitochondrial matrix. Now this substance is then acted on by another enzyme or series of enzymes in the process called _____________
citric acid cycle
In the Citric Acid Cycle, Acetyl-CoA are split into _________ & ___________
The hydrogen ions are highly reactive and eventually combine with oxygen that has diffused into the mitochondria.
hydrogen ions and carbon dioxide
This reaction releases a tremendous amount of energy that is used to convert large amounts of ADP to ATP.
This requires large numbers of ______________ that are actually part of the mitochondria.
protein enzymes
The initial event in ATP formation is the removal of the electrons, the hydrogen atom, thereby converting it to __________
hydrogen ion
The terminal event of the hydrogen ion is moving through large globular proteins called ___________, which protrudes
to the membranes of the mitochondria, which presents in the mitochondrial matrix.
ATP synthetase
The enzyme ATP synthetase uses the energy and movement of the hydrogen ions to effect the conversion of ADP to ATP, and
hydrogen ions combined with oxygen to form the by-product ________
water
The newly formed ATP is transported out of the mitochondrion to all parts of the cell, where it synergizes the function of the cell.
Chemosmotic mechanism of ATP formation.
ATP is mainly used in many cellular processes such as:
- membrane transport as it occurs in the sodium potassium pump which transports sodium out of the cell and potassium into the cell
- the synthesis of chemical compounds throughout the cell;
- mechanical work, as occurs with the contraction of muscle fibers or with ciliary and ameboid motion.
The _________ movement is typically seen in white
BLOOD cells. This amoeboid movement is related to the surroundings.
EX: white blood cells through tissues to form tissue macrophages
Amoeboid
Typically, amoeboid motion begins with the protrusion of ___________from one end of the cell.
This results in a continuous exocytosis, which informs a new cell membrane at the leading edge of the pseudopodium and continual endocytosis of the membrane in the rear portions of the cell. The white blood cells reacts to the substances produced by other tissues
pseudopodium
The most important initiator of ameboid locomotion is the process called ______________, which results from the appearance of certain chemical substances in the tissues
chemotaxis
Any chemical substance that causes chemotaxis to occur is called a ___
chemotactic substance
from an area of lower concentration toward an area of higher concentration
ameboid locomotion move toward the source of a chemotactic substance
positive chemotaxis
Some cells move away from
the source, which is called
negative chemotaxis
A whip-like movement of the cilia on the surface of
the cells. It occurs in two places of the body:
a. The respiratory airways
b. The uterine tubes
CILIARY MOVEMENT
e nasal cavity and lower
respiratory airways, the whiplike motion of cilia causes a layer of mucus to move at a rate of about____________ toward the pharynx
1 cm/min
In the uterine tubes, the cilia cause
slow movement of fluid from the ostium of the uterine tube toward the uterus cavity; this movement of fluid transports the ovum from the _________
ovary to the uterus.
______cilia on the surface of each epithelial cell inside the respiratory passageways
200
The cilium is covered by an outcropping of the cell membrane, and it is supported by 11
microtubules
____ double tubules located around the
periphery of the cilium and ____single tubules down the
center
9
2
Each cilium is an outgrowth of a structure
that lies immediately beneath the cell membrane, called the ________ of the cilium.
basal body
____________of a sperm is similar to a cilium; in fact,
it has much the same type of structure and the same type of contractile mechanism.
is much longer and moves in quasi-sinusoidal waves instead of whiplike movements
flagellum
9 double tubules a
2 single tubules - are all linked to one another by a complex of protein cross-linkages;
this total complex of
tubules and cross-linkages is called the ______________
axoneme
Third, two conditions are necessary for continued beating of the axoneme after removal of the other structures of the cilium:
(1) the availability of ATP and
(2) appropriate ionic conditions, especially appropriate concentrations of
magnesium and calcium.
during forward motion of the cilium, the double tubules on the front edge of the cilium slide ____toward the tip of the cilium, while those on the back edge remain in place
outward
multiple protein arms composed of the protein dynein, which has adenosine triphosphatase (ATPase) enzymatic activity, project from each_____________ toward an adjacent double tubule
double tubule
the release of energy from ATP in contact with the
ATPase dynein arms causes the heads of these arms to “crawl” rapidly along the surface of the adjacent ________________
double tubule
