Term
|
Definition
network of protein filaments extending throughout the cell
~eukaryotic cells only
~variety of functions |
|
|
Term
| 3 types of protein filaments from cytoskeleton: |
|
Definition
-intermediate fibers
-microtubules
-actin filaments (microfilaments) |
|
|
Term
|
Definition
-intermediate in size (>actin filaments, -heterogeneous family of proteins
-provides mechanical strength
-to animal cells during growth or movements
-can stretch a sheet of cells and they remain intact and together; cells rupture when stretched without intermediate filaments
-nuclear lamina strengthen nuclear envelope |
|
|
Term
|
Definition
-tubulin protein subunits
-long hollow tubes; rigid
-rapidly assembled/disassembled
-tracklike structures in interphase cell
-spindle fibers move chromosomes in dividing cell
-flagellum and cilium in ciliated cell
plus end – adding subunits
minus end – removing subunits
subunits bound to GTP assemble
if GTP GDP, microtubules disassemble
certain compounds block assembly/disassembly (e.g. colchicine, taxol)
GTP tubulin molecules add to end of microtubule
GDP tubulin is released to the cytosol
transport of vesicles, organelles, or other cargo along microtubules
inward transport of inside of microtubule, outward transport outside |
|
|
Term
|
Definition
- move molecular cargo in cells
ex. dynein and kinesin
-move along microtubules-ATP is the energy source
-different motor proteins transport different cellular cargo
-heavy chains at bottom attach to microtubule
-light chains extend above heavy chains intertwined with each other |
|
|
Term
| Microtubules also move organelles within the cell |
|
Definition
-some stable microtubule structures exist- cilium and flagellum
-microtubules in cilia and flagella arranged in characteristic 9 + 2 array |
|
|
Term
| Actin filaments (microfilaments) |
|
Definition
-actin protein subunits
-flexible helical filaments
-most abundant cytoskeletal proteins |
|
|
Term
| Actin filaments allow cells to perform a variety of functions |
|
Definition
|
|
Term
|
Definition
-formed by actin subunits
-has plus and minus end |
|
|
Term
| Assembly of actin monomers into polymers requires ATP |
|
Definition
| -ADP subunit disassembles, releasing subunit |
|
|
Term
| Actin can associate with myosin (family of motor proteins) |
|
Definition
| -muscles contract by actin and myosin sliding past each other |
|
|
Term
| Extracellular Matrix (ECM) |
|
Definition
-between cells in tissues
-made up of high amounts of polysaccharides and proteins
-secreted by cells outside of plasma membrane |
|
|
Term
| Cells may be organized into tissues |
|
Definition
collagen- important protein in animal ECM
most common protein in mammals
fibroblasts- cells of connective tissues (e.g. skin, tendons); produce ECM |
|
|
Term
| Examples of cell-cell junctions in animal tissues |
|
Definition
-tight junctions: seals neighboring cells together in an epithelial sheet to prevent leakage of molecules between them
-desmosomes: joins the intermediate filaments in one cell to those in a neighbor
-gap functions: allows the passage of small water soluble ions and molecules in the
cytosol, movement of ions and small molecules between adjacent animal cells (openings in plasma membranes in animal cells) |
|
|
Term
|
Definition
-connects adjacent plant cells and movement of materials between cells
Big difference between gap function: opening in cell wall as well as membrane) |
|
|
Term
|
Definition
- also known as cell communication
-Communication between:
1. Cell-cell
Molecule produced/released by one cell (signaling cell), and detected/received by another cell (target cell)
2. Cell-environment
-Transduction- Information can change from one form to another form |
|
|
Term
|
Definition
Cell signaling molecules may include
Proteins
Amino acids
Nucleotides
Steroids
Dissolved gases
Ex. ethalene: gas released from “bad” apple, cause all apples to rot |
|
|
Term
| In animal cells there are several forms of cell signaling |
|
Definition
1. Endocrine cell-releases hormone, hormone enters blood stream (long distance), exits blood stream and interacts with target cell containing the appropriate receptor (hormones are the cell signaling molecule)
2. Paracrine-signaling cell releases signaling molecule, interacts within a close region, target cells respond to signaling molecule (local mediator—nearby)
3. Neuronal-nerve cells; nerve cells release signal molecule (ex: neurotransmitter), can be over long distance, at the end of cell the signaling molecule is released to a very particular nervous cell
4. Contact-dependent: signaling cells are in contact with the target cell (signal molecule on surface of one cell) |
|
|
Term
| To respond to signal, target cell must have correct receptor |
|
Definition
-There is a specificity between signal molecule and acceptor)
-Cells may have many different receptors, and respond to many different signals
-Same signal molecule may cause different responses in different target cells
-Cells may respond to many kinds of signals, different combinations of signals can induce different responses
-Ex of responses: survive, division, differentiate, die |
|
|
Term
|
Definition
Extracellular signals can alter protein activity, thus altering behavior of cell.
-Ex of behavioral changes:
-altered metabolism
-altered gene expression
-altered cell shape or movement
-Extracellular signal is transduced, new intracellular signal is generated (second messenger). |
|
|
Term
|
Definition
-Signal cascades distribute and amplify intracellular signals
-The process that follows after receiving the signal molecule on the cell membrane |
|
|
Term
|
Definition
| Receptor proteins may be on cell surface (plasma membrane), or inside cell (intracellular) |
|
|
Term
|
Definition
-Most signal molecules are large, hydrophilic, and unable to cross membrane (cell surface receptors)
-Some signal molecules are small or hydrophobic, and able to diffuse across membrane (intracellular receptors) |
|
|
Term
| Nitric oxide (NO; a gas) acts locally; |
|
Definition
-can diffuse across membranes
-half-life of about 5-10 seconds
-NO can cause muscle cells to relax, increasing blood flow
-NO is an important signal molecule in many types of organisms, including plant cells.
-NO activates defense mechanisms following pathogen attack
-**NO is not N2O, nitrous oxide-laughing gas**
-Two examples of medical uses of NO:
1. Nitroglycerine, precursor of NO, causes dilation of blood vessels, increasing blood flow to heart, relieving angina
2. Viagra (and similar drugs) increases production of NO, results in dilation of blood vessels and increasing blood flow |
|
|
Term
| Cell surface receptors are typically proteins that span membrane |
|
Definition
-exposed outside the cell-binds signal molecule
-exposed inside the cell-relays signal intracellularly |
|
|
Term
| Three basic classes of cell surface receptors |
|
Definition
1. ion-channel-linked receptors
2. G-protein linked receptors (enzyme binds GTP)
3. Enzyme-linked receptors |
|
|
Term
| ion-channel-linked receptors |
|
Definition
- ligand-gated channel; converts chemical signal to electrical signal
(ligand is signal molecule) once signal attaches, membrane opens to allow ions to cross |
|
|
Term
| G-protein linked receptors (enzyme binds GTP) |
|
Definition
-release intracellular signals, second messengers
-G-protein-linked receptors are linked to g protein
-Largest family of cell-surface receptors
-Prokaryotic cells appear to lack G-proteins
-Polypeptide chain crosses membrane 7 times; binds signal molecule on extracellular side |
|
|
Term
| General structure and function of G-protein-linked receptor |
|
Definition
-G-protein inactive when bond to GDP
-Active when bond to GTP
-G-protein is activated after the receptor receives a signal
- Activated subunits of G-proteins activate target proteins
-Target proteins are typically either ion channels or membrane bound enzymes
-Example: activated subunits of G-protein bind to K+ channel in membrane
- Example: activated subunit of G-protein bind to enzyme in membrane (production of second messengers) |
|
|
Term
|
Definition
| release intracellular signals, second messengers |
|
|
Term
|
Definition
| cAMP and Calcium ions (Ca2+) |
|
|
Term
|
Definition
-Most common target for g-protein is membrane bound enzyme called adenylyl cyclase (adenylate cyclase)
-ATP-->cyclic AMP
-cAMP is a major second messenger molecule in cells
-cAMP can link extracellular signals to changes in gene expression
-cAMP-->protein-->into nucleus-->protein activated--> regulate gene expression |
|
|
Term
|
Definition
–important intracellular second messengers
-changes in Ca2+ concentration in egg cell following fertilization by sperm cell
-Calmodulin-Ca2+ binding protein (calcium modulator)
-changes conformation when bound to Ca2+
-calmodulin-Ca2+ complex alters activity of target enzymes |
|
|
Term
| Cell response to extracellular signals by second messengers may be fast of slow |
|
Definition
1. Rapid responses-modification of activity of existing proteins (Seconds to mins)
-activates or deactivates these already existing proteins)
2. Slow responses-altered gene expression (mins to hrs)
-involves the synthesis of new proteins |
|
|
Term
|
Definition
-produced from the division of existing cells
-parent cell--> daughter cell, daughter cell
-the life cycle of a cell is called the cell cycle |
|
|
Term
| cell cycle has both growth phases and division phases |
|
Definition
1. cell growth and chromosome replication
2. chromosome segregation
3. cell division |
|
|
Term
| when cells reproduce, they must: |
|
Definition
-replicate certain cell contents:
1. DNA
2. New protein synthesis
3. New membrane synthesis
-distribute cell contents to two cells
*nucleus, mitochondria, and chloroplast divide during cell division |
|
|
Term
| Prokaryotic cell division |
|
Definition
-eukaryotic genome is larger than prokaryotic genome
-eukaryotic genome is divided in numerous chromosomes
-prokaryotic genome is a single molecule
-eukaryotic cells have organelles
-bacterial cells can divide every 20 minutes through binary fission similar to division of mitochondria and chloroplast |
|
|
Term
|
Definition
-four phases of cell cycle:
-Interphase (growth phases)
1. G1- Gap; new daughter cells begin life, cell grows, increases cytoplasmic contents
2. S- Synthesis; DNA replication
3. G2- Gap; cell growth, preparation for division
-Division phase
4. M
-mitosis- nuclear division
-cytokinesis- cytoplasmic division |
|
|
Term
| length of time required for completing eukaryotic cell cycle varies: |
|
Definition
-early frog embryo cells- 30 minutes
-human liver cells- 1 year
-intestinal epithelial cells- 12 hours |
|
|
Term
|
Definition
-cell cycle is highly regulated
-trigger points
-2 prominent checkpoints
-DNA damage stops cycle in G1
-two groups of proteins, cyclins and cyclin-dependent kinases (Cdk) regulate all cycle events
-components of cytoskeleton involved in various event so of cell cycle |
|
|
Term
|
Definition
-enter S- triggers DNA replication
-enter M- triggers mitosis machinery- assembles mitotic spindle
-exit M- triggers completion of mitosis and proceeds to cytokinesis |
|
|
Term
|
Definition
1. Enter M
-is DNA intact?
-is all DNA replicated?
2. Enter S
-is environment favorable?
-is DNA intact? |
|
|
Term
| DNA damage stops cycle in G1 |
|
Definition
| inhibitor protein developed to make complex inactive |
|
|
Term
| components of cytoskeleton involved in various event so of cell cycle: |
|
Definition
-microtubules of the mitotc spindles
-actin and myosin filaments of the contractile ring
-recall, microtubules may be rapidly assembled and disassembled from tubulin subunits |
|
|
Term
|
Definition
-during M-phase, the nucleus and cytoplasm divide
-although nuclear division is a major event of the cell cycle, other cell components must be distributed to new daughter cells
-ex: ER and Golgi fragment and are redistributed
-mitochondria and chloroplast are divided (binary fission) and distributed to new cells |
|
|
Term
|
Definition
[part of M-phase, the nucleus divides]
*occurs during formation of somatic cells
1. Prophase
2. Prometaphase
3. Metaphase
4. Anaphase
5. Telophase |
|
|
Term
|
Definition
-replicated chromosomes condense
-mitotic spindle assembles between two centrosomes in cytosols, which have begun to move apart
-mitotic spindles bind to centromeric kinetochore |
|
|
Term
|
Definition
-starts with breakdown of nuclear envelope
-chromosomes now attach to spindle microtubules via kinetochores
-chromosomes undergo active movement |
|
|
Term
|
Definition
-chromosomes align at equator of spindle, midway between spindle poles
-paired kinetochore microtubules on each chromosome attach to opposite poles |
|
|
Term
|
Definition
-paired chromatids synchronously separate to form two daughter chromosomes, each pulled slowly to pole
-microtubules get shorter, spindle poles move apart
-both contribute to separation |
|
|
Term
|
Definition
-two sets of daughter chromosomes arrive at the poles of the spindle
-new nuclear envelope reassembles around each set, completing the formation of two nuclei and marking the end of mitosis
-contractile ring begins to assemple |
|
|
Term
|
Definition
[part of M-phase, the cytoplasm divides]
-cytoplasm is divided in two by a contractile ring of actin and myosin filaments (proteins)
-cleavage- contractile ring pinches in the cell to create two daughter cells
-cells with a cell wall cannot divide by cleavage
-new cell walls form at equatorial plate from the center of the cell to the edge
-water pressure allows cell wall to expand and allows cells to get larger in size |
|
|
Term
| Mechanisms of nuclear division |
|
Definition
(both in M-phase of cell cycle)
1. Mitosis
2. Meiosis |
|
|
Term
|
Definition
| any cell other than a gamete |
|
|
Term
|
Definition
| has two sets of chromosomes (2n) |
|
|
Term
|
Definition
reductional division, occurs during formation of gametes, not division of
gametes. If they were FORMED by mitosis, then fertilization would be 4n. |
|
|
Term
|
Definition
| sex cells (sperm and egg) |
|
|
Term
|
Definition
| has one set of chromosomes (1n) |
|
|
Term
| fertilization results in the formation of a zygote that is diploid |
|
Definition
-occurs only in sexually reproducing organisms
-go through two cell divisions |
|
|
Term
|
Definition
-1 round of division
-2 daughter cells/cycle
-Somatic cells produced
-Chromosome # of daughter cells same as parent cell |
|
|
Term
|
Definition
-2 rounds of division
-4 daughter cells/cycle
-Gametes produced
-Chromosome # of daughter cells one-half of parent cell |
|
|
Term
| Why doesn't mitosis or meiosis occur in bacteria cells? |
|
Definition
|
|
Term
|
Definition
| -a variety of cell defense mechanisms exist; different types of cells may utilize different mechanisms |
|
|
Term
| Plant cells must defend against: |
|
Definition
-bacteria
-viruses
-nematodes- infect plant cells and feed on contents
-fungi- feeds on cells without killing them
-herbivores |
|
|
Term
| Two types of plant defenses: |
|
Definition
1. Physical defense
2. Chemical defense |
|
|
Term
| Physical defense of plants |
|
Definition
*attempt to keep organism out of cell
-cell wall- provides support and protection for cell
-some produce secondary cell walls (s1, s2, s3)
-cuticle- cover many plant cell wall surfaces
-composed of fatty acids, waxes, etc.
-resist pathogens
-reduce water loss
-leaf hairs- specialized cells on some plant surfaces, protect plants from herbivores, etc. |
|
|
Term
| Chemical defense of plants |
|
Definition
| *aimed at killing off the organism |
|
|
Term
| 3 classes of secondary products |
|
Definition
1. Alkaloid compounds
-caffeine, nicotine, cocaine, morphine, also cyanogenic compounds
2. Terpenes
3. Phenolic compounds
-used to add flavors/taste to food
-cinnamon, ginger, green tea, peppers, nutmeg, vanilla |
|
|
Term
| used for communication- plant cell signaling |
|
Definition
1. Oligosaccharides
2. Plant hormones
3. Electrical signals |
|
|
Term
|
Definition
| -small units of polysaccharides (carbohydrates)when herbivore is eating through cell wall, the polysaccharides are broken down into oligosaccharides, these oligosaccharides signal to the cell “Hey! We’re under attack!”; can also be signaled by oligosaccharides in pathogen cell wall |
|
|
Term
| Plant cell-fungal cell interactions |
|
Definition
-Compounds released by fungal cell wall, plant uses fungal cell’s compound for transcription of defense cells to help defend against fungi. Then fungal cell releases toxin that
blocks transcription of defense cells, then plant releases enzymes that break down the toxins that are blocking the
transcription! |
|
|
Term
|
Definition
-following attack, plant cell accumulates toxic compounds
-plant cell dies; zone of dead plant cells containing toxins
-Ex: hypersensitive response in tobacco |
|
|
Term
|
Definition
*proteins produced by vertebrate immune system
~also referred to as immunoglobulins (highest concentration in blood plasma)also in tears, saliva, mother’s milk, etc. |
|
|
Term
|
Definition
| molecular ligands that bind tightly to antibodies |
|
|
Term
|
Definition
| anything that binds to a protein |
|
|
Term
|
Definition
type of white blood cell, produces antibodies
-the antibodies function as receptors on B cell; antigen attaches sending signal to B cell to make more of these antibodies |
|
|
Term
|
Definition
-two identical large polypeptides (heavy chains)
-two identical smaller polypeptides (light chains)
-joined by disulfide bonds
-each antibody has two antigen binding sites at tips of “Y” where light and heavy chains cross |
|
|
Term
|
Definition
| an individual animal can make billions of different antibody molecules, each with a distinct antigen-binding site |
|
|
Term
| Five classes of antibodies |
|
Definition
Class Concentration in serum
Most common class:
IgG 8-16 mg/ml
IgA 1-4 mg/ml
IgM 0.5-2 mg/ml
IgE 10-400 ng/ml
IgD |
|
|
Term
|
Definition
-antimicrobial peptides
-all animals’ and deaths
-broad spectrum of activities |
|
|
Term
|
Definition
|
|
Term
|
Definition
death from damage or injury
-cell swells and bursts
-occurs slowly |
|
|
Term
|
Definition
*programmed cell death
-cell shrinks
-DNA fragments
-Cytoplasm contracts
-occurs rapidly (cell suicide)
-Cellular components broken down (basically disassembled from within)
-Sequestered in vesicles (avoids inflammatory response) |
|
|
Term
| Mitochondria contain proteins that initiate programmed cell death |
|
Definition
caspases (type of protesases)—protein that breaks down specific proteins (degradative proteins)
-called caspase cascade |
|
|
Term
| functions of programmed cell death |
|
Definition
kills cells that:
-generated in excess
-developed improperly
-completed their function
-are harmful |
|
|
Term
| functions of programmed cell death |
|
Definition
kills cells that:
-generated in excess
-developed improperly
-completed their function
-are harmful |
|
|
Term
| programmed cell death in plants |
|
Definition
-hypersensitive response
-formation of xylem vascular tissue
-formation of aerenchyma tissue
-plant senescence |
|
|
Term
| formation of xylem vascular tissue |
|
Definition
| xylem tissue transports primarily water |
|
|
Term
| formation of aerenchyma tissue |
|
Definition
| gas transport to plant parts requiring O2 |
|
|
Term
| senescence in soybean plants |
|
Definition
-programmed breakdown of tissues/cells
-“resources” directed to developing seeds |
|
|
Term
|
Definition
-All life forms comprised of cells
-Simplest organisms are single-celled
-More complex organisms are multicellular
-Properties of life emerge at level of cell
-Proteins and DNA are biologically important and necessary for life, but they are not sufficient for life. |
|
|
Term
| because of role as catalyst and information coding molecule, RNA has emerged as key molecule in origin of life on Earth |
|
Definition
-it is likely that living systems began with evolution of catalytic RNA molecules
-autocatalytic molecules generate more of themselves
-catalytic RNAs also catalyze replication of other RNA types |
|
|
Term
|
Definition
-discovered in early 1980’s
-Thomas Cech’s lab at University of Colorado
-Cech awarded Nobel Prize in 1989
-***SO, NOT ALL ENZYMS ARE PROTIENS*** |
|
|
Term
| advantage of DNA based systems |
|
Definition
-double helical structure of DNA is more stable
-double stranded DNA supports repair systems |
|
|
Term
| Formation of membrane to surround “first Cell” |
|
Definition
| Recall-phospholipids spontaneously form bilayers in water |
|
|
Term
| Simplest cell that has been identified |
|
Definition
-Mycoplasma genitalium
-Bacterium with 482 genes
-Smallest known genome of any living organism |
|
|
Term
|
Definition
-First cells to evolve were prokaryotic cells
-Perhaps similar to a bacterial cell
-A broad diversity of life has evolved form common ancestral cell
-First cells were prokaryotic-like and lacked organelles
-Where did organelles come from?
-Nucleus
-Mitochondria
-Chloroplast |
|
|
Term
|
Definition
-Formation of nucleus and ER may have resulted form invagination of plasma membrane
-With nucleus, cell is considered to be eukaryotic |
|
|
Term
|
Definition
| thought to have originated when aerobic prokaryotic cell engulfed by early eukaryotic cell. |
|
|
Term
|
Definition
| thought to have originated in manner similar to mitochondria but photosynthetic bacterium engulfed by early eukaryotic cell |
|
|
Term
| Evidence supporting endosymbiotic origin of mitochondria and chloroplasts |
|
Definition
-both surround by double membrane (envelope)
-both have own genome (albeit a small genome)
-ribosomes more similar to bacterial than eukaryotic cytosolic ribosomes
-mitochondria and chloroplasts divide by process of fission, similar to bacterial division. |
|
|
Term
| Early photosynthetic organisms used H2S (ect) s source of e- and H+ (protons). |
|
Definition
-H2S -> 2H+ + 2e- + S
-2H2O -> 4H+ + 4e- + O2 |
|
|
Term
| Use of H2O as an e- and H+ donor came later |
|
Definition
|
|
Term
| present day atmospheric oxygen concentration is about: |
|
Definition
|
|
Term
| Evolution of new metabolic systems |
|
Definition
-aerobic respiration
-advantages of oxygen-rich atmosphere include more efficient respiration (aerobic vs. anaerobic).
-Anerobic-2 ATP/glucose
-Aerobic-36 ATP/glucose
-mitochondria takes up about 95% of oxygen, reduces to water
-4e- + 4H+ + O2 -> 2H2O |
|
|
Term
| Formation of atmospheric Ozone (O3) |
|
Definition
-O3 absorbs incoming UV radiation
-solar radiation:
-O2 -> 2 O
-O + O2 -> O3 |
|
|
Term
| Oxygenic toxicity problems |
|
Definition
-toxic forms of oxygen cause cell damage
-reduced, highly reactive forms of O2 produce ROS |
|
|
Term
| reactive oxygen species are often short-lived, but dangerous |
|
Definition
| -damage includes: lipids (membrane fluidity, leakage), proteins (receptors), DNA (bases, enzymes, sugars) |
|
|
Term
|
Definition
-superoxide radical
-hydrogen peroxide
-hydroxyl radical |
|
|
Term
| aerobic cells survive only bc of antioxidant defenses |
|
Definition
| cell anti-oxidant defenses are not 100% effective...some damage to lipids, proteins, and DNA does occur |
|
|
Term
| evidence exists for ROS involvement in |
|
Definition
-defense against microbial infections
-plays role in cell signaling |
|
|
Term
|
Definition
| a common ancestral prokaryotic cell |
|
|
Term
| upper cell size is determined by... |
|
Definition
| ability of material to enter and exit the cell by diffusion |
|
|
Term
|
Definition
| uses light as source of energy |
|
|
Term
|
Definition
| uses chemicals as energy source |
|
|
Term
|
Definition
| capable of living on CO2 as sole carbon source |
|
|
Term
|
Definition
| uses only organic carbon as carbon source |
|
|
Term
| greater than 99% of energy in biosphere comes from... |
|
Definition
|
|
Term
| estimated total number of prokaryotic cells on earth |
|
Definition
|
|
Term
| prokaryotic cells have been found in range of extreme environments: |
|
Definition
“extremophiles”
-low/high temperatures (<0°C to >100°C)
-low/high pH (2-12)
-high pressures (deep ocean) |
|
|
Term
|
Definition
-prokaryotic cell
-no membrane-bound organelles still functions in some ways that eukaryotic cells do but without organelles; ex., photosynthesis occurs without chloroplast in cytosol
-unicellular organism
-cell wall (no cellulose)
-conduct cellular activity without organelles
-has DNA, but not in nucleus (does not even have a nucleus)
-diverse metabolisms
ex., nitrogen fixation: bacteria (nitrogen fixers) infects the roots of plants forming nodules (if sliced open, would be red – similarly to hemoglobin); the bacteria takes up gaseous nitrogen from the atmosphere, breaks triple bonds, and changes it into amino acids, which then changes into proteins
-exist in “extreme” environments (extremophiles)
-temperature, pH, pressure, with or without O2 |
|
|
Term
|
Definition
-has a cell wall (cellulose)
-plastids/chloroplasts (used to carry out photosynthesis)
-vacuoles may be large (pushes chloroplasts to end of cell to optimize light energy uptake)
-complete photosynthesis
-light energy -> chemical energy
-inorganic carbon -> organic carbon |
|
|
Term
| Liver cell (mammalian) hepatocyte |
|
Definition
-metabolically versatile (do lots of different things)
-liver requires up to 30% of total body energy expenditures
-role in detoxification
-takes-up, processes, produces, releases more compounds than most other cells
-rapidly switch between opposing metabolic pathways
{ from X > > > Y, to Y > > > X} shows flexibility
-help maintain level oxidizable fuel levels in blood (carbohydrates, lipids)
-urea cycle enzymes; proteins and nitrogen compound metabolisms |
|
|
Term
| Red blood cell (mammalian) |
|
Definition
-terminally differentiated (cannot divide)
-functions to deliver O2 to tissues
-mature red blood cells lack nucleus and other organelles
-nucleus and internal membranes around organelles disassembled (during RBC maturation)
-ribosomes are broken down
-very high levels of hemoglobin (hemoglobin is a protein)
-“all cytosol” cell
-remains functional about 100-120 days (3 months) |
|
|
Term
| red blood cell retains ability for: |
|
Definition
~glycolysis (but no aerobic respiration)
~pentose phosphate pathway |
|
|
Term
| glycolysis (but no aerobic respiration) |
|
Definition
-glucose -> 2 pyruvate -> 2 lactate
(ATP produced, NAD+ regenerated)
-net yield 2 ATP
-ATP needed for Na+/K+ pump |
|
|
Term
| pentose phosphate pathway |
|
Definition
-generates NADPH
-NADPH needed for antioxidant maintenance
Recall that too much oxygen is toxic therefore aerobic cells have to have some kind of way to keep from being poisoned… antioxidant mechanisms protect the cell from toxic levels of oxygen, and NADPH is needed for antioxidant maintenance) |
|
|
Term
| Cell signaling molecules may include: |
|
Definition
Proteins
Amino acids
Nucleotides
Steroids
Dissolved gases |
|
|
Term
| In animal cells several forms of cell signaling: |
|
Definition
Endocrine
Paracrine
Neuronal
Contact dependent |
|
|
Term
|
Definition
| releases hormone, hormone enters blood stream (long distance), exist blood stream and interacts with target cell containing the appropriate receptor |
|
|
Term
|
Definition
| signaling cell releases signaling molecule, interacts within a close region, target cells respond to signaling molecule |
|
|
Term
|
Definition
| nerve cells; nerve cells release signal molecule (ex: neurotransmitter), can be over long distance, at the end of cell the signaling molecule is released to a very particular nervous cell |
|
|
Term
|
Definition
| signaling cells are in contact with the target cell |
|
|
Term
|
Definition
~acts locally
-can diffuse across membranes
-half-life of about 5-10 seconds
-can cause muscle cells to relax
-is an important signal molecule in many types of organisms, including plant cells
**NO is not N2O, nitrous oxide-laughing gas** |
|
|
Term
| Two examples of medical uses of NO |
|
Definition
Nitroglycerine, precursor of NO, causes dilation of blood vessels, increasing blood flow to heart, relieving angina
Viagra (and similar drugs) increases production of NO, results in dilation of blood vessels and increasing blood flow |
|
|
Term
| Three basic classes of cell surface receptors |
|
Definition
a. ion-channel-linked receptors
b. G-protein linked receptors (enzyme binds GTP)
c. Enzyme-linked receptors
(a) ligand-gated channel; converts chemical signal to electrical signal
(b) and (c) release intracellular signals, second messengers |
|
|
