Chapter 2: The Cell and Its Function Flashcards
2 major parts of the cell
Nucleus and Cytoplasm
What structure separates the nucleus from the cytoplasm?
Nuclear membrane
What structure separates the cytoplasm of the cell from the surrounding fluids?
cell membrane or plasma membrane
The different substances that make up the cell is called the:
protoplasm
5 basic substances that compose the protoplasm:
Water Electrolytes Proteins Lipids Carbohydrates
According to Guyton, most cells are comprised mainly of water. With the EXCEPTION of ______ cells
Fat cells (adipocytes)
**In fat cells (adipocytes), triglycerides often account for as much as 95% of the cell mass.
Average water concentration of the cell:
70-85%
Which of the following ions is found only in smaller quantities in the cell? A. Bicarbonate B. Calcium C. Phosphate D. Magnesium
B. Calcium
Important ions in the cell include potassium, magnesium,
phosphate, sulfate, bicarbonate, and smaller quantities
of sodium, chloride, and calcium.
After water, the most abundant substances in the cells are:
Proteins
Proteins constitute what percentage of the cell mass?
10-20%
Which type of proteins present in the cell are mainly in the form of long filaments that are polymers of many individual protein molecules?
Structural proteins
The other type is the functional protein
What structure provides the cytoskeletons of cellular organelles such as cilia, nerve axons, mitotic spindles, and tangled mass of thin filamentous tubules that that hold the parts of the cytoplasm and nucleoplasm together in their respective compartments?
Microtubules
These structural proteins are found outside the cell, especially in the collagen and elastin fibers of connective tissue, and elsewhere, such as in blood vessel walls, tendons, and ligaments.
Fibrillar proteins
- *Microtubules - structural proteins inside
- *Fibrillar proteins - structural proteins outside
These types of proteins are mainly the enzymes of the cell and, in contrast to the fibrillar proteins, are often mobile in the cell fluid.
Functional proteins
Which type of cellular protein is adherent to membranous structures inside the cell and catalyzes specific intracellular chemical reactions?
Functional proteins
**These proteins are mainly the enzymes of the cell and, in
contrast to the fibrillar proteins, are often mobile in the
cell fluid.
Phospholipids and cholesterol together constitute __% of the total cell mass?
2%
Phospholipids and cholesterol are mainly insoluble in water and therefore are used to form the cell membrane and intracellular
membrane barriers that separate the different cell compartments.
Lipid component of the cell that is known as “neutral fat”
Triglyceride
These cells store the body’s main storehouse of energy-giving nutrients that can later be used to provide energy wherever it is needed in the body.
Adipocytes
**In fat cells (adipocytes), triglycerides often account for as much as 95% of the cell mass. 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 it is needed in the body.
What is the maximum amount of carbohydrates stored in muscle and liver cells? (percentage)
3% in muscle cells and 6% in liver cells
**Most human cells do not maintain large stores of carbohydrates; the amount usually averages only about 1% of their total mass but increases to as much as 3% in muscle cells and, occasionally, to 6% in liver cells.
This is the insoluble polymer of glucose that can be depolymerized and used rapidly to supply the cell’s energy needs
Glycogen
**carbohydrate in the form of dissolved glucose is always present in the surrounding extracellular fluid so that it is readily available to the cell. Also, a small amount of carbohydrate is stored in cells as glycogen, an insoluble polymer of glucose that can be depolymerized and used rapidly to supply the cell’s energy needs.
The loss of which organelle will result to immediate cessation of 95% of the cell’s energy release from nutrients?
Mitochondria
In membranes of organelles, protein molecules often penetrate all the way through membranes, thus providing specialized pathways, often organized into actual ______, for passage of specific substances through membranes
Pores
The approximate percent composition of the cell membrane as to proteins:
55%
55% proteins 25% phospholipids 13% cholesterol 4% other lipids 3% carbohydrates
The approximate percent composition of the cell membrane as to phospholipids:
25%
55% proteins 25% phospholipids 13% cholesterol 4% other lipids 3% carbohydrates
The approximate percent composition of the cell membrane as to cholesterol
13%
55% proteins 25% phospholipids 13% cholesterol 4% other lipids 3% carbohydrates
The approximate percent composition of the cell membrane as to carbohydrates
3%
55% proteins 25% phospholipids 13% cholesterol 4% other lipids 3% carbohydrates
The thin, double-layered film of lipids that is continuous over the entire cell surface
Lipid bilayer
** The basic structure of the cell membrane is a lipid bilayer, which is a thin, double-layered film of lipids—each layer only one molecule thick—that is continuous over the entire cell surface. Interspersed in this lipid film are large globular proteins.
What are the 3 main types of lipids that compose the basic lipid bilayer?
Phospholipids
Sphingolipids
Cholesterol
What is the amino alcohol component of the lipid, found mostly in nerve cell membranes, which serves several functions, including protection from harmful environmental factors, signal transmission, and adhesion sites for extracellular proteins?
Sphingosine
**Sphingolipids, derived from the amino alcohol sphingosine, also have hydrophobic and hydrophilic groups and are present in small amounts in the cell membranes, especially nerve cells. Complex sphingolipids in cell membranes are thought to serve several functions, including
protection from harmful environmental factors, signal
transmission, and adhesion sites for extracellular proteins.
Which lipid component of the cell membrane determines the degree of permeability (or impermeability) of the bilayer to water-soluble constituents of body fluids?
Cholesterol
**Cholesterol controls much of the fluidity of the membrane as well.
These protein structures on the cell membrane have selective properties that allow preferential diffusion of some substances over others.
Channels or pores (integral proteins)
**Many of the integral proteins provide structural channels (or pores) through which water molecules and water-soluble substances, especially ions, can diffuse between extracellular and intracellular fluids. These protein channels also have selective properties that allow preferential
diffusion of some substances over others.
Which of the following is unable to penetrate the lipid layer of the cell membrane? A. Oxygen B. CO2 C. Urea D. Alcohol
C. Urea
**The lipid layer in the middle of the membrane is
impermeable to the usual water-soluble substances, such as ions, glucose, and urea. Conversely, fat-soluble
substances, such as oxygen, carbon dioxide, and alcohol, can penetrate this portion of the membrane with ease.
Which integral proteins of the cell membrane allow transport of substances that otherwise could not penetrate the lipid bilayer?
Carrier proteins
The process by which carrier proteins transport substances in the direction opposite to their electrochemical gradients for diffusion
Active transport
These molecules bind and interact with cell membrane receptors causing conformational changes in the receptor protein, which in turn enzymatically activates the intracellular part of the part of the protein or induces interactions with second messengers.
Ligands
These are proteins in the cytoplasm that relay signal from the extracellular art of the receptor to the interior of the cell
Second messengers
Which types of cell membrane protein provides a means of conveying information
about the environment to the cell interior?
Integral proteins
This type of cell membrane protein functions almost entirely as enzymes or as controllers of transport of substances through cell membrane pores.
Peripheral proteins
These molecules comprise most of the integral proteins of the cell membrane
glycoproteins
About one-tenth of the cell membrane lipid molecules are:
glycolipids
These compounds, attached loosely to the outer surface of the cell, are carbohydrates bound to small protein cores.
proteoglycans
The loose carbohydrate coat of the entire outside surface of the cell
Glycocalyx
Which of the main molecular compositions of the cell membrane gives it a negative electrical charge?
Carbohydrates
- *The carbohydrate moieties attached to the outer surface of the cell have several important functions:
1. Many of them have a negative electrical charge, which gives most cells an overall negative surface charge that repels other negatively charged objects.
Which of the following is an important function of the carbohydrate moieties of the outer surface of the cell?
A. Allow repulsion to other negatively changes objects
B. Provide a mechanism of attachment to other cells
C. Act as receptors
D. For immune reactions
E. All of the above
Function of carbs of the outer cell membrane:
“NARI”
- Negative charge for repulsion
- Attachment to other cells via the glycocalyx
- Receptors (e.g. insulin)
- Immune reactions
14ed20
This is the jelly-like fluid portion of the cytoplasm in which the particles are dispersed, containing mainly dissolved proteins, electrolytes, and glucose
Cytosol
This is a network of tubular structures in the endoplasmic reticulum
Cisternae
What is the watery medium in the space inside the tubules and vesicles of the ER that is different from the fluid in the cytosol?
Endoplasmic matrix
Electron micrographs show that the space inside the endoplasmic reticulum is connected with the space between the two membrane surfaces which organelle?
Nucleus
“Electron micrographs show that the space inside the endoplasmic reticulum is connected with the space between the two membrane surfaces of the nuclear membrane.”
There are minute granular particles attached to the outer surfaces of many parts of the endoplasmic reticulum
Ribosomes
**The ribosomes are composed of a mixture of RNA and proteins; they function to synthesize new protein molecules in the cell
This organelle functions for the synthesis of lipid substances
Smooth (Agranular) Endoplasmic Reticulum
This organelle is usually composed of four or more stacked layers of thin, flat, enclosed vesicles lying near one side of the nucleus.
Golgi apparatus
The Golgi apparatus is prominent in which type of cells?
Secretory cells
**This apparatus is prominent in secretory cells, where it is located on the side of the cell from which secretory substances are extruded
These are small cellular structures that are pinched off from the ER and shortly thereafter fuse with the Golgi apparatus.
Transport vesicles
also called ER vesicles
What intracellular materials are typically digested by lysosomes?
- damaged cellular structures
- food particles that have been ingested by the cell
- unwanted matter such as bacteria
What is the usual diameter of a lysosome?
250-750 nanometers in diameter
What does the lipid bilayer membrane of the lysosomes contain?
hydrolase (digestive) enzymes
**Lysosomes are surrounded by typical lipid bilayer membranes and are filled with large numbers of small granules, 5 to 8 nanometers in diameter, which are protein aggregates of as many as 40 different hydrolase (digestive) enzymes
This type of enzyme is capable of splitting an organic compound into 2 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.
Hydrolytic enzymes
What are the products of the hydrolysis of protein, glycogen, and lipid?
Protein = amino acids Glycogen = glucose Lipid = fatty acids and glycerol
How are peroxisomes believed to be formed?
By self-replication or by budding off from the sER
What enzymes do peroxisomes contain?
oxidases
What highly oxidizing substance is formed by the action of oxidases as these combine O2 with H+?
Hydrogen peroxide (H2O2)
**Several of the oxidases are capable of combining oxygen with hydrogen ions derived from different intracellular chemicals to form hydrogen peroxide (H2O2).
Hydrogen peroxide associates with which oxidase enzyme to oxidize many substances that may otherwise be poisonous to the cell?
Catalase
Which fatty acids are hydrolyzed by peroxisomes?
Long-chain fatty acids
About half the alcohol that a person drink is detoxified into _________ by the peroxisomes of the liver cells
acetaldehyde
Which system forms almost all of the secretory substances of a cell?
Endoplasmic Reticulum–Golgi Apparatus System
These are infoldings of the inner membrane of the mitochondria that form shelves or tubules onto which OXIDATIVE ENZYMES ATTACH
cristae
Which portion of the mitochondria contains large quantities of dissolved enzymes necessary for extracting energy from nutrients?
Matrix within the inner cavity
Which organelles of the cell are self-replicative
Mitochondria and Peroxisomes
This refers to the outer zone of the cytoplasm
Ectoplasm
Which cellular filaments are found in large quantities in the ectoplasm, and form an elastic support for the cell membrane?
actin microfilaments
These cellular filaments are generally strong ropelike filaments that often work together with microtubules, providing strength and support for the fragile tubulin structures.
Intermediate filaments
What is the main function of intermediate filaments?
mechanical
less dynamic than actin microofilaments or microtubules
in which cells do you find the following intermediate filaments:
- Desmin
- Neurofilaments
- Keratins
- Desmin = muscle cells
- Neurofilaments = neurons
- Keratins = epithelial cells
This is a special type of stiff filament that is composed of polymerized TUBULIN molecules that is used in all cells
Microtubules
These are 2 structures composed of stiff microtubules and are important for mitosis
Centrioles and Mitotic Spindles
These structures serve as the conveyor belts for the intracellular transport of vesicles, granules, and organelles such as mitochondria.
Microtubules
The special process by which a cell splits to form two daughter cells, each of which receiving one of the two sets of DNA genes.
Mitosis
This is the period between mitoses
Interphase
The maximum molecular weight that a nuclear pore allows to pass through with reasonable ease
44,000
** each pore is only about 9 nanometers in diameter
These are highly staining structures contained within the nuclei of most ceells
nucleoli
These are the accumulation of large amounts of RNA and proteins of the types found in ribosomes.
nucleolus
What is the size of the smallest known virus?
15 nm
This is the essential life-giving constituent of the small virus, embedded in a coat of protein.
nuclei acid
This involves simple movement through the membrane caused by the random motion of the molecules of the substance.
diffusion
This involves the actual carrying of a substance through the membrane by a physical protein structure that penetrates all the way through the membrane
Active transport
This means the ingestion of minute particles that form vesicles of extracellular fluid and particulate constituents inside the cell cytoplasm
Pinocytosis
This means the ingestion of large particles, such as bacteria, whole cells, or portions of degenerating tissue.
Phagocytosis
This is the only means whereby most large macromolecules, such as most proteins, can enter the cell.
Pinocytosis
This is a latticework of fibrillar protein found on the inside of the cell membrane, beneath of the coated pits.
Clathrin
The process by which antibodies intermediate in phagocytosis as they bind onto to the phagocyte receptors, dragging the bacterium along with it.
Opsonization
This refers to the indigestible substances that is left of the digestive vesicles
residual body
**The products of digestion are small molecules of substances such as amino acids, glucose, and phosphates that can diffuse through the membrane of the vesicle into the cytoplasm.
What make up the digestive organs of the cells?
pinocytotic and phagocytotic vesicles containing lysosomes
Which organelle is responsible for the regress of tissues into smaller size?
lysosome
This the process by which the entire cell is digested by hydrolases due to severe damage
Autolysis
What is the bactericidal agent contained by lysosomes that dissolves bacterial cell wall?
lysozyme
What is the bactericidal agent contained by lysosomes which binds iron and other substance before they can promote bacterial growth?
lysoferrin
What is the pH of the acid contained within lysosomes which activates the hydrolases and inactivate bacterial metabolic systems?
5.0
This is a housekeeping process whereby obsolete organelles and large protein aggregates are degraded and recycled
Autophagy
Worn-out organelles are transferred to lysosomes by which double-membrane structures?
autophagosomes
*formed in the cytosol
This process contributes to the routine turnover of cytoplasmic components, and it is a key mechanism for tissue development, cell survival when nutrients are scarce, and maintenance of homeostasis.
Autophagy
The approximate lifespan of a mitochondrion of a liver cell
10 days
How does the cell keep the endoplasmic reticulum from growing beyond the needs of the cell?
By continuous breaking away of the ER vesicles or transport vesicles, most migrating rapidly to the Golgi apparatus
Which organelle is responsible in producing the enzymes that control glycogen breakdown for energy?
endoplasmic reticulum
Which organelle functions for the detoxification of substances such as drugs?
Endoplasmic Reticulum (smooth)
Which organelle forms large saccharide polymers bound with small amounts of protein, such as hyaluronic acid and chondroitin sulfate?
Golgi Apparatus
**Although a major function of the Golgi apparatus is to provide additional processing of substances already formed in the endoplasmic reticulum, it can also synthesize certain carbohydrates that cannot be formed in the endoplasmic reticulum.
These substances are the major components of proteoglycans secreted in mucus and other glandular secretions; the major components of the ground substance, or nonfibrous components of the extracellular matrix, outside the cells in the interstitial spaces, which act as fillers between collagen fibers and cells; the are principal components of the organic matrix in both cartilage and bone; and are important in many cell activities, including migration and proliferation.
Hyaluronic acid and Chondroitin sulfate
What are the types of vesicles formed by the Golgi Apparatus?
Secretory vesicles and Lysosomes
Upon bathing with amino acids, how much time does it take for a glandular cell to secrete proteins from the surface of the cells?
within 1-2 hours
Which ions enter the cell and stimulate opening of the cell membrane’s outer surface and extrusion of its contents outside the cell?
Calcium ions
**Calcium ions interact with the vesicular membrane and cause its fusion with the cell membrane, followed by exocytosis—opening of the membrane’s outer surface and extrusion of its contents outside the cell. Some vesicles, however, are destined for intracellular use.
Which organs essentially convert all carbohydrates into glucose before they reach the other cells of the body?
Digestive tract and Liver
Inside the cell, foodstuffs chemically react with which molecule to channel the release of energy in the proper direction?
oxygen
Which phosphate group of ATP is the primary phosphate group that is hydrolyzed when the energy is needed to drive anabolic reactions?
Gamma phosphate
What connects the last 2 phosphate radical to the rest of the ATP molecule?
high-energy phosphate bonds
Under the ‘physical and chemical conditions of the body’, each of the high-energy bonds of ATP contains about ________ calories of energy per mole of ATP.
12,000 calories
This is the energy currency of the cell
adenosine triphosphate
In which compartment of the cell does glycolysis occur?
cytoplasm
This substance, derived from pyruvic acid is dissolved in the mitochondrion matrix through a sequence of chemical reactions for the purpose of extracting its energy.
Acetyl-coenzyme A
In the citric acid cycle, acetyl-CoA is split into its component parts: __________ and _________.
Hydrogen atoms and Carbon dioxide
**CO2 diffuses out of the cell to the lungs
Hydrogen atoms react with oxygen
The tremendous amount of energy used by the mitochondria to convert large amounts of ADP and ATP comes from the which reaction?
Combination of hydrogen atoms (component of acetyl-coA) with oxygen
What is the initial event in the conversion of large amounts of ADP to ATP in the mitochondrion?
Removal of an electron from the hydrogen atom, converting it to a hydrogen ion
What is the terminal event in the conversion of ADP to ATP?
Combination of hydrogen ions with oxygen to form water (Cytochrome c oxidase/ Complex IV) and release of large amounts of energy to ATP synthetase.
This mitochondrial enzyme uses the energy from the hydrogen ions to convert ADP to ATP.
ATP synthetase (Complex V of the respiratory chain)
This refers to the crawling-like movement of an entire cell in relation to its surroundings, such as movement of WBC through tissues.
Ameboid movement
To provide locomotion for a cell this structure projects away from the cell body and partially secures itself in a new tissue area; the remainder of the cell is pulled towards the said structure
pseudopodium
In the general principle of ameboid motion, the formation of new cell membrane occurs in which part of the cell?
leading part of the pseudopodium
In the general principle of ameboid motion, the continual absorption of the membrane occurs in which part of the cell?
mid and rear portions of the cell
The attachment of the pseudopodium to the surrounding tissues is caused by which structures?
This is caused by RECEPTOR PROTEINS that line the inside of exocytotic vesicles.
** When the vesicles become part of the pseudopodial membrane, they open so that their insides evert to the outside, and the receptors now protrude to the outside and attach to ligand in the surrounding tissues
What type of movement does
Tissue macrophages
What type of movement do fibroblasts use to move into a damaged area to help repair the damage
ameboid locomotion
Which type of cellular movement partially accounts for the rapid spread of sarcomas from one part of the body to another?
Some types of cancer cells, such as sarcomas, which arise from connective tissue cells, are especially proficient at ameboid movement. This partially accounts for their relatively rapid spreading from one part of the body to another, known as metastasis.
This refers to the important control or initiator of ameboid locomotion which results from the appearance of certain chemical substances in the tissues
Chemotaxis
This refers to any chemical substance that causes chemotaxis to occur.
Chemotactic substance
What specific process occurs when a chemotactic cell moves away from the sources of a chemotactic substance, from an area of higher concentration to an area of lower concentration?
negative chemotaxis
**Most cells that exhibit ameboid locomotion move toward the source of a chemotactic substance—that is, from an area of lower concentration toward an area of higher concentration. This is called positive chemotaxis. Some cells move away from the source, which is called negative chemotaxis.
This is the rate of movement of mucus toward the pharynx made possible by the whiplike motion of motile cilia
1 cm/ min
How many double tubules around the periphery support a motile cilium?
9 double tubules (doublets)
The cilium is covered by an outcropping of the cell membrane, and it is supported by 11 microtubules—nine double tubules located around the periphery of the cilium and two single tubules down the center
How many singlets support the center of the motile cilium?
2 single tubules (singlets)
How many microtubules support a motile cilium in total?
11 microtubules (9 doublets and 2 singlets)
How many microtubules support a non-motile cilium?
9 (9 doublets in the periphery but 0 singlets in the center)
This is the structure that lies immediately beneath the cell membrane from which the cilium grows.
basal body or kinetosome
How does a flagellum move in comparison to a motile cilium?
it moves in quasisinusoidal waves
instead of whiplike movements in a motile cilium
In ciliary movement, to which direction of stroke is the fluid propelled towards?
fast-forward stroke
This refers to the total complex of tubules and cross-linkages that forms the core of the cilium or flagellum
axoneme
What are the two conditions that are necessary for the continued beating of the axoneme after the removal of the other structures of the cilium?
- the availability of ATP
2. appropriate ionic condition, especially appropriate concentrations of Ca++ and Mg++
Which axonemal protein form cross-links between adjacent doublets and function to restrict the sliding motion brought by the activation of dynein arms, causing the axoneme to bend?
nexin
Which ionic concentrations are important for the continuous beating of an axoneme despite of the removal of the other structures of the cilium?
Calcium and Magnesium ions
This protein, which has an ATPase activity, forms the protein arms that project from each double tubule toward an adjacent double tubule
Dynein
What paired structures of the axoneme, when activated by ATP, bind the neighboring microtubule causing the doublets to slide past each other?
dynein arms
Which tubules of the cilia are believed to transmit electrochemical signals to activate the dynein arms?
2 central single tubules
Which type of cilia serve as the sensory “antennae” as they coordinate cellular signaling pathways involved in chemical and mechanical sensation, signal transduction and cell growth?
Primary cilia (nonmotile cilia)
e.g., flow sensors of epithelial cells of the renal tubules
What is the condition manifesting with large fluid-filled cysts may develop with defects in signaling by primary cilia in renal tubular epithelial cells?
polycystic kidney disease
Both neutrophils and macrophages contain an abundance of lysosomes filled with _______ enzymes especially geared for digesting bacteria and other foreign protein matter.
proteolytic enzymes
The lysosomes of macrophages (but not of
neutrophils) also contain large amounts of _________, which digest the thick lipid membranes possessed by some bacteria, such as the tuberculosis bacillus.
lipases
