Final Exam Flashcards
Unregulated cell division leads to what?
Cancer
Abnormal cell growth is controlled by what genes?
Protooncogenes and tumor suppressor genes
Proteins form these genes control cell growth and differntiation. If mutated they become known as oncogenes.
Protooncogenes
These genes control unregulated progression through the cell cycle. Loss of function of these genes predisposes cells to cancer.
Tumor suppressor genes
What are the two theories of cancer?
Clonal evolution model and the stem cell theory
This theory of cancer believes that a tumor develops from a single mutated cell and that every mutated cell has the potential to develop another tumor.
Clonal evolution model
What is the stepwise process of cancer development?
Initiation, Promotion, Progression, and Metastasis
Self sufficient growth signals, ignoring of anti-growth signals, evasion of apoptosis, limitless replication potential, angiogenesis, reprogramming of energy metabolism, evasion of immune destruction, and metastasis are all considered to be what?
The Hallmarks of Cancer
This process is due to injury or disease. Cells increase in size and lyse. Intracellular contents are inflammatory.
Necrosis
During this process cells shrink in size, plasma membrane buds off (blebs), phosphatidylserine moves from the inner to outer leaflet, mitochondria release cytochrome c, chromatin in the nucleus condenses and cells are finally engulfed by the macrophages. Another name for this is programmed cell death
Apoptosis
This is a specialized white blood cell that engulfs foreign invaders and cells that are no longer needed.
Macrophages
Macrophages bind to ____ on the apoptotic cell, internalizing and degrading the cell, preventing ____
Phosphatidylserine, Inflammation
This state occurs when the number of cells is relatively constant due to cell replication and cell death.
Homeostasis
Apoptosis is internally initiated by the insertion of what protein into the mitochondrial membrane?
Bax
After binding of Bax to the mitochondrial membrane within the cell this molecule triggers apoptosome complex in the cytoplasm, which leads to a caspase cascade to destroy protein and DNA.
Cytochrome C
Apoptosis is externally initiated by what?
Death receptors
In the initiation of apoptosis by an external signal, ____ ligand binds to its respective death receptor, thereby recruiting ____. The recruiting of these domains activate procaspase ___ to caspase ___.
Fas, Fas-associated death domain (FADD), 8, 8.
These three components make up the death inducing signaling complex when apoptosis is initiated by an external signal?
Fas receptor, FADD, and caspase 8.
These are proteases that mainly function during apoptosis.
Caspases
Which caspases are initiator caspases?
Caspases 2, 8, 9, and 10
Which caspases are effector caspases?
Caspases 3, 6, and 7
What proteins compose the prosurvival (antiapoptotic) proteins?
Members of Bcl-2 family (the BAD proteins)
What proteins compose the prodeath (apoptotic) proteins?
Bak and Bax proteins
What are some neurodegenerative diseases in which apoptosis is no longer working?
- Schizophrenia (altered neuronal apoptosis)
- Dementia and Alzheimer’s (localized apoptosis)
What are some hallmarks of aging?
Genomic instability, telomere attrition, epigenetic alterations, loss of protein homeostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intracellular communication
This is a hallmark of aging and is characterized by an accumulation of DNA damage throughout life, loss of DNA repair mechanisms, and damage to the nuclear lamina.
Genomic instability
This is a hallmark of aging and is characterized by a lack of telomerase and special shelterin proteins hide telomere damage from repair mechanisms.
Telomere attrition
This is a hallmark of aging and is characterized by histone modifications (methylation), DNA modifications, Chromatin remodeling, and transcriptional alterations.
Epigenetic alterations
This is a hallmark of aging and is characterized by a decreased synthesis of chaperone proteins in aging and protein degradation.
Loss of protein homeostasis
This is a hallmark of aging and is characterized by anabolic pathways, slower replication, and sirtuins signal nutrient scarcity and promote cell survival and catabolism.
Deregulated nutrient sensing
This is a hallmark of aging and is characterized by the production of reactive oxygen species (ROS), a lower efficiency in ATP generation, and mitohormesis, which is the activation of defense mechanisms by toxins attacking mitochondria.
Mitochondrial dysfunction
This is a hallmark of aging and is characterized by a decrease in hematopoiesis and a decrease in the cell cycle due to more DNA damage and overexpression of INK4A (cyclin inhibitor)
Stem cell exhaustion
This is a hallmark of aging and is characterized by an increase in inflammation. Enhanced activation of NF-kB, senescent cells produce more inflammatory cytokines, less SIRT1.
Altered intracellular communication
This is a cell state characterized by a lack of replication. These cells do not re-enter the growth cycle, but are still metabolically active.
Senescence
Where is senescence beneficial? Detrimental?
It is beneficial for tumor suppression, but detrimental during aging
What are some causes of cellular senescence?
Telomere shortening, reactive oxygen species (ROS), and oncogene/tumor suppressor genes
What are some traits of cells in senescence?
Growth arrest, apoptotic resistance, change in gene expression, chromatin modifications, and senescence-associated beta-galactosidase
A decreased expression of cyclins and transcription factors and active cyclin-dependent kinase inhibitors p21 and p16 result in what type of cell cycle for senescent cells?
A irreversible cell cycle
Chromatin modifications in senescent cells result in more of this type of chromatin?
Heterochromatin
Sirtuins can both induce and inhibit what process?
Senescence
This is mainly produced in mitochondria from oxidative phosphorylation, can damage DNA in mitochondria, and the most common one is superoxide.
Reactive oxygen species
Senescent cells produce high levels of what two things?
Inflammatory cytokines and matrix metalloproteinases (MMPs)
This ion creates conditions of electropositivity outside of the cell and electronegativity inside the cell. It is primarily concentrated inside of nerves.
Potassium
This ion is concentrated outside of the nerve. Diffusion of it inside of the cell creates a membrane potential of +61mV.
Sodium
The membrane of a nerve is 100 times more permeable to what ion?
Potassium
A nerve in the resting state is known as what?
Polarized
This process is characterized by a nerve’s membrane becoming permeable to Na+. There is a large influx of Na into the cell.
Depolarization
This process is characterized by a nerve’s sodium channels closing and potassium channels opening. There is an efflux of K+.
Repolarization
The nerve action potential utilizes what type of channels?
Voltage-gated sodium and potassium channels.
Voltage-gated channels have three components what are they?
- Activation gate: opens when the membrane potential changes
- Selectivity filter: selects for a particular ion
- Inactivation gate: found on sodium channels (located on the interior of the cell)
When do the sodium channels open?
When the membrane potential of a nerve is less negative (-70 to -50mV)
When do the sodium channels close?
Close due to the membrane potential becoming less negative
When do the potassium channels open?
They open as the membrane becomes less negative and when the sodium channels close
When do the potassium channels close?
When resting membrane potential is reached
What type of channels are calcium channels in terms of an action potential?
They are slow channels that provide a sustained depolarization
What type of channels are sodium channels in terms of an action potential?
They are fast channels that initiate an action potential
What is the process of an action potential?
- An event causes the membrane of a nerve to depolarize
- Na influx
- Positive feedback to further increase the membrane potential and sodium influx
- Sodium channels begin to close and potassium channels begin to open
- Repolarization
- Hyperpolarization (Refractory period)
- Return to resting potential
What are some factors that can cause excitation?
Anything that causes Na+ to diffuse inside the cell in high enough concentrations due to:
- Mechanical
- Chemical
- Electrical
What are some inhibitors of excitation?
- High extracellular fluid of Ca2+ concentration
- Local anesthetics inhibit Na channels from opening.
Action potential are what type of response?
All or nothing
What is the all or nothing principle?
- Depolarization down the nerve only occurs if the conditions are right
- If some point on the membrane is not able to generate enough voltage, the spread of depolarization stops
What is necessary for reestablishing ionic concentration gradients?
Na+/K+ pumps (3 Na out 2 K in)
What is the Na+/K+ pump dependent on to function?
ATPase and a sodium concentration
In some action potentials, particularly the heart, there can be a plateau. What is this caused by?
A delay in repolarization
Where can repetitive self-induced discharge of action potentials occur in the body?
Heart, smooth muscle, and neurons of the CNS
What is repetitive discharge of action potentials required for?
- Rhythmic heart beat
- Peristalsis of intestines
- Rhythmic control of breathing
How does repetitive discharge of action potentials occur?
It occurs due to membranes becoming more permeable to K+
What are the two types of synapses?
Chemical and electrical
These synapses transmit a signal in one direction from the presynaptic neuron to the postsynaptic neuron
Chemical synapses
What are the two types of neurotransmitters that can be released from the presynaptic terminal?
Excitatory and inhibitory
What are the two types of receptors that can be found on the postsynaptic membranes?
Excitatory and inhibitory
What are the two types of domains that the postsynaptic membrane contains?
Binding domain and the ionophore
What are the two types of ionophores?
Ion channel and the second messenger activator
What cations are involved in ion channels?
Mostly sodium, but some potassium and calcium. They are excitatory
What anions are involved in ion channels?
Chloride. It is inhibitory
Are ion channels fast or slow?
Fast
Second messenger signaling in neurons uses what type of proteins? What does the neurotransmitter bind to?
Heterotrimeric G proteins. The neurotransmitter binds to Galpha
What are the four classes of small molecule, fast-acting neurotransmiters?
- Class I (Ach)
- Class II (amines: NE, epinephrine, dopamine, serotonin, histamine)
- Class III (amino acids: GABA, glycine, glutamate, aspartate)
- Class IV (nitric oxide)
How are small molecules, fast acting neurotransmitters absorbed?
Active transport into vesicles
This small molecule neurotransmitter is secreted from the motor cortex, basal ganglia, motor neurons that innervate skeletal muscle, and postganglionic neurons in the sympathetic nervous system. It is mostly excitatory.
Acetylcholine
This small molecule neurotransmitter is secreted by terminals of neurons in the brain, hypothalamus, and postganglionic neurons of the sympathetic nervous system. It is mostly excitatory.
Norepinephrine
This small molecule neurotransmitter is secreted by neurons in the substantia nigra and are inhibitory.
Dopamine
This small molecule neurotransmitter is secreted in the spinal cord and is inhibitory.
Glycine
This small molecule neurotransmitter is secreted in the spinal cord, cerebellum, basal ganglia, and cortex. It is inhibitory.
GABA
This small molecule neurotransmitter is secreted in sensory pathways and the cerebral cortex. It is excitatroy.
Glutamate
This small molecule neurotransmitter is secreted in the brain stem and spinal cord. It is an inhibitor of pain.
Serotonin
This small molecule neurotransmitter is secreted in areas of the brain responsible for long term memory and behavior. It is not stored in vesicles, modifies metabolic functions in postsynaptic neurons, and is excitatory.
Nitric oxide
What are the types of neuropeptides, slow acting transmitters or growth factors?
Hypothalamic-releasing hormones, pituitary peptides, peptides that act on the gut and brain
Where are neuropeptides, slow acting transmitters, or growth factors synthesized?
Ribosomes
Where do post-translational modifications of neuropeptides occur?
Golgi complex
What is the membrane potential of a resting neuron? Excitatory? Inhibitory?
- Resting: -65mV in spinal motor neurons -80mV in peripheral nerves
- Excitatory: -45mV
- Inhibitory: -70mV
What is summation?
40-80 presynaptic terminals discharging at the same time to generate and action potential.
What neurotransmitter is primarily involved with presynaptic inhibition?
GABA, which causes the opening of anion channels (Cl-)
What amount of voltage is required to reach threshold for the firing of an action potential?
10-20mV
What is temporal summation?
Rapidly successive discharges of 1 presynaptic terminal
Neurons are often excited, but not to the extent that threshold is reached. This is known as what?
Facilitated
This is a special characteristic of dendrites that is characterized by a decrease in membrane potential as it moves from dendrite to soma.
Decremental conduction
This is a special characteristic of synaptic transmission, which is when overexcited neurons lose their excitability after a while. It is protective against excess neuronal activity and occurs mainly due to exhaustion of stores of transmitters.
Fatigue
Does alkalosis increase or decrease the excitability of a neuron?
Increase
Does acidosis increase or decrease the excitability of a neuron?
Decrease
Lack of oxygen or this condition for a few seconds causes inexcitability of some neurons?
Hypoxia
What do excitatory drugs, such as caffeine do to the neurons?
They reduce threshold for excitation
What do inhibitory drugs, such as anesthetics do to the neurons?
They increase threshold for excitation.
What is the minimum amount of time for synaptic delay?
0.5 milliseconds
Where do motor neurons originate from?
Anterior horns of the spinal cord
This is a highly branched nerve fiber outside of the muscle fiber plasma membrane.
Motor end plate
How is Ach secreted?
- Nerve impulse reaches neuromuscular junction
- Ca channels open and flux into the presynaptic terminal
- Ca attracts Ach vesicles to the membrane next to dense bars
- Vesicles fuse with the membrane and Ach is released
The end plate potential can be weakened and therefore not reach threshold due to medications and toxins. What is the end result in muscle?
Paralysis
Each impulse at a neuromuscular junction is 3x stronger than the end plate potential necessary to stimulate contraction. This is known as what?
Safety factor
Repetitive discharge in muscles can lead to what?
Fatigue
This enzyme is found within the synaptic space and degrades Ach to acetyl-CoA and choline.
Acetylcholinesterase
This is an autoimmune disease where antibodies attack Ach receptors at the neuromuscular junction. Results in paralysis and death if severe enough.
Myasthenia gravis
Which action potential is faster, a muscle or a nerve?
Nerve (~50-60m/sec) while a muscle is (3-5m/sec)
Do muscle action potentials penetrate the muscle fiber?
No, it is transmitted along the T-tubules
These structures run from the cell membrane all the way through the muscle fiber. They branch, interlace myofibrils, and have one end open to extracellular fluid.
Transverse (T) tubules
During this event, the T-tubules are stimulated and the release of Ca occurs. The Ca concentration increases 500x and this event lasts ~1/20 second.
Calcium ‘pulse’
Compare eukaryotes and prokaryotes.
- Eukaryotes: have a nucleus, linear DNA, and internal membrane bound organelles
- Prokaryotes: lack a nucleus, have circular DNA, and lack internal membrane bound organelles
What are the two types of glycocalyx in prokaryotes? What are their functions?
- Capsule: firmly attached to the cell surface and may prevent bacteria from being recognized by the host
- Slime layer: loosely attached to cell surface and allows prokaryotes to attach to surfaces
This external structure of bacteria is responsible for movement, are composed of three parts (filament, hook, and basal body), and are not present in all bacteria.
Flagella
This is a sticky bristle-like projection used by bacteria to adhere to one another, to hosts, and to substances in the environment. They are shorter than flagella and play an important role in biofilms.
Fimbrae
These are tubules composed of pilin. They are longer than fimbrae, but shorter than flagella. They mediate the transfer of DNA from one cell to another (conjugation)
Pili
This bacterial structure provides structure and shape to the cell as well as protecting it from osmotic forces. They are composed of peptidoglycan.
Cell walls
What are the two basic types of bacterial cell walls?
Gram (+) and Gram (-)
This bacterial cell wall has a relatively thick layer of peptidoglycan, contains teichoic acids, and appears purple following the Gram staining procedure.
Gram (+) bacterial cell walls
This bacterial cell wall has a thin layer of peptidoglycan. Has a bilayer membrane outside the peptidoglycan composed of phospholipids, proteins, and lipopolysaccharides. They appear red following the Gram staining procedure.
Gram (-) bacterial cell walls
This is a potent endotoxin that dead cells release. This release may trigger fever, vasodilation, inflammation, shock, and blood clotting.
Lipid A
Bacterial cytoplasmic membranes maintain what?
Concentration and electrical gradients
The ribosomes of prokaryotes have their sized in Svedbergs (S). How big are they?
70S. They are composed of 2 subunits (30S and 50S)
These are unique structures produced by some bacteria that are used as a defensive strategy of unfavorable conditions.
Endospores
These are miniscule, acellular, infectious agents that have either DNA or RNA.
Viruses
What is the extracellular state of a virus called?
Virion
What are the components of the majority of viruses?
Nucleic acid and a capsid
Viral replication is dependent on what?
The host’s organelles and enzymes to produce new virions
What type of replication do viruses typically undergo?
Lytic replication: the cell most often dies
Term refers to cells being replaced at the same rate as they are lost
Homeostasis
What process occurs between your fingers and toes to “sculpt your digits
Apoptosis
What is the resting potential of a nerve?
-70 to -80mV
Where does plateauing of an action potential typically occur?
In heart tissue
This is a type of active transport in which the contents are modified before entering the prokaryote.
Group translocation
