Cell Biology Flashcards
Briefly explain some of the differences between a Eukaryotic and a Prokaryotic cell.
1) Eukaryotic cells are found in higher animal and plants, has a true nucleus, membrane enclosed organelles, no cell walls, has a plasma membrane with sterols and carbohydrates that serve as receptors, has ribosomes that are large (80S) and small (70S in organelles).
2) Prokaryotic cells are found in bacteria, has no organelles, no true nucleus, have a chemically complex cell wall, no plasma membrane, has ribosomes of smaller size (70S).
Why is PCN effective at killing bacterial cells but doesn’t harm human cells?
PCN breakdown cell walls, which human cells lack.
What are some examples of membrane-enclosed organelles present in Eukaryotic cells but not Prokaryotic cells?
Lysosomes, Golgi complex, Endoplasmic Reticulum, Mitochondria, and Chloroplasts.
Which bacteria causes walking pneumonia and why doesn’t PCN work on it?
Mycoplasm bacteria - PCN doesn’t work because it doesn’t have cell walls.
A “typical” Eukaryotic cell consists of which 3 components?
1) Plasma membrane
2) Cytoplasm
3) Organelles
Give a brief description of the functions of the following cell structures:
1) Nucleus
2) Nucleolus
3) Lysosome
4) Mitichondria
1) Nucleus Serves as repository for genetic information
2) Nucleolus - Synthesizes ribosomes
3) Lysosome - Contains digestive enzymes
4) Mitichondria - Generates ATP by oxidative phosphorylation
Give a brief description of the functions of the following cell structures:
1) Golgi Apparatus
2) Vesicle
3) Endoplasmic Reticulum
4) Ribosome
1) Golgi Apparatus - Processes and packages proteins for delivery
2) Vesicle - Delivers synthesized proteins to their destinations
3) Endoplasmic Reticulum - Synthesizes steroid hormones
4) Ribosome - Synthesizes proteins
What’ s the difference between the Nucleus and the Nucleolus?
1) Nucleus is a large membrane bound organelle in the middle of the cell that serves as a repository for genetic information.
2) Nucleolus is located inside the nucleus and is composed of RNA, it synthesizes ribosomes.
What’s the difference between a Lysosome and a Peroxisome?
1) Lysosomes functions as the intracellular digestive system to breakdown most cellular components to their constituents such as amino acids, carbs, and nucleotides.
2) Peroxisomes are larger than lysosomes and specifically use oxygen to remove hydrogen atoms from specific substrates which produce H2O2. Catalase then uses the H202 to oxidize substances such as phenols, formic aid, formaldehyde, and alcohols.
Function of the Smooth ER vs. Rough ER
1) Smooth ER - Detoxification/Lipid metabolism; Steroid hormone synthesis
2) Rough ER - Synthesis of proteins (mRNA –> Proteins and lipid components of the cells and organelles, folding of proteins, sensing cellular stress.
In regards to Endoplasmic Reticulum Stress, protein folding amount and rate can be decreased by which 3 things?
1) Cell stress
2) Mutations
3) Random errors during protein synthesis
The normal Endoplasmic Reticulum environment can be disturbed by which 3 things?
1) Viral infections
2) Environmental toxins
3) Mutant protein expression
What are some of the protective pathways used to facilitate protein folding and prevent formation of “off-pathway types” in the Endoplasmic Reticulum?
1) Initiation of apoptosis (cell death) when misfolded proteins not repaired by the ER are seen in some diseases.
2) ER collective mediation by signaling pathways in response to accumulation of misfolded proteins (aka the unfolded protein response (UPR).
(T/F?) Unfolded Protein Response leads to diseases.
True
UPR-associated inflammation is associated to which specific diseases?
1) Alzheimer’s
2) Parkinson’s
3) Prion diseases
4) ALS
5) Diabetes
6) Age-related cell dysfunction
7) Sepsis
Important functions of Lysosomes noted on our PPs?
1) Intracellular digestion using acidic hydrolyses
2) Used by phagocytes to destroy pathogens
3) Play central role in cellular adaptation.
Describe some of the diseases associated with errors in the lysosomal process?
1) Alterations in this signal pathway = lysosomal storage disease, neurodegenerative disease, and cancer.
2) Lysosomal storage disease occur from genetic defects
3) Tay Sachs Disease - Lack of lysosomal hexosaminidase
4) Gout - undigested uric acid accumulates in lysosomes
(T/F?) Peroxisomes also play an important role in the synthesis of specialized phospholipids?
True
What is the chemical equation for how Peroxisomes use peroxide to oxidize other substrates to yield water and oxygen.
H2O2 + R’H2 –> R’ + 2H2O2
Which cell structure contains secretory vessels and cisternae?
Golgi Apparatus
Which cell structure is also know as the “Refining Plant”?
Golgi apparatus
Which cell structure has a double membrane, with an increased surface area of the inner membrane because of folding called crystae?
Mitochondria
What’s the function of the cytoskeleton?
1) Cell shape and internal organization
2) Allows movement of substances in the cell and movement of external projections (i.e. cilia and flagella).
Define Mechanotransduction?
The cellular processes that translate mechanical stimuli into biochemical signals, allowing cells to adapt to their surroundings.
Microtubules vs. Microfilaments (Actin)?
1) Microtubules - have an asymmetric morphology and forms centrioles during division.
2) Microfilaments (Actin) - Motility and cell/tissue shape
Which drugs affect microtubules and microfilaments?
1) Paclitaxil (Taxol) - Stabalizes microtubules and causes mitotic arrest.
2) Colchicine, Vinblastine - Disassembles microtubules (prevents motility and or mitosis).
(T/F?) Some anesthetic drugs bind to tubular proteins?
True
What are the functions of the cell’s plasma membrane?
1) To separate intracellular and extracellular environments
2) To provide cellular motility and shape
3) To provide the selective transport system
4) To provide cell to cell communication via protein receptors.
5) To provide cell to cell recognition via carbohydrates
Define Amphipathic
A molecule with one part of it being hydrophobic and the other part being hydrophilic.
Hydrophobic vs. Hydrophilic
1) Hydrophobic - Uncharged or water-fearing/fat soluble. i.e. the tail of a phospholipid.
2) Hydrophilic - Charged or water-loving/water soluble . i.e. the head of a phospholipid.
Characteristics of GABA receptors?
1) Most important inhibitory neurotransmitter in the CNS
2) Ligand-gated ion channel receptors in the cell membrane of neurons in CNS
3) GABA binds, allow Cl- ions into the cell = hyper polarization of neuron inhibits electrical nerve signals.
(T/F?) Propofol directly stimulates the GABA receptor.
True
5 drugs that regulate receptor?
1) Barbituates
2) Benodiazepines
3) Propofol
4) Etomidate
5) Volatiles
What are the 3 kinds of effects that Anesthetic drugs have on GABA receptors?
1) Potentiation - Enhances existence GABA inhibitory effect
2) Direct Gating - Activates receptor by binding directly (no GABA)
3) Inhibition - Paradoxically inhibits GABA
What is the effect of Barbiturates, propofol and volatiles on the GABA receptors?
They increase the frequency of the channel opening and average length of time it opens.
(T/F?) Barbiturates, propofol, and volatiles, do NOT alter conductance (the rate at which ions cross the open channel).
True
Different anesthetics act on distinct subtypes of GABA receptor? Which receptors do the following drugs act on:
1) Propofol
2) Etomidiate
3) Benzos
1) Propofol - B2
2) Etomidiate - B2 and B3
3) Benzos - G2
(T/F?) Mutations in subunits affect binding sites and sensitivity to anesthetics?
True
Characteristics of Glycine receptors?
1) Inhibits Cl- ion channel
2) Glycine acts as an inhibitory neurotransmitter in the spinal cord and brainstem.
3) Propofol and Pentobarbital potentiates glycine activated currents by increasing affinity of the receptor for glycine.
Characteristics of Hyperpolarization-Activated Cyclic Nucleotide Gated channels (HCN)?
1) They are leak channels permeable to Na+ or K+
2) Pacemaker or “funny” channels - active in cardiac tissue and CNS.
3) Produce Ih current - regulates resting membrane potential.
4) It is modulated by cyclic nucleotides (i.e. cAMP)
5) Affected by binding of propofol, ketamine, and volatiles.
Characteristics of NMDA receptors?
1) Stimulated by the excitatory neurotransmitter glutamate, which opens the ion channel allowing N+, K+, AND Ca++ ions to enter the cell.
2) influx of positive ions stimulates an action potential and the transmission of an electrical nerve impulse.
How does Ketamine work?
Ketamine is a noncompetitive NMDA receptor antagonist. By blocking the receptor, afferent neural impulses are transmitted, but not interpreted by the cortex.
Where are 5HT receptors found?
CNS, PNS, SM, BV, GI and Platelets.
What kind of receptor is the 5HT3? Which ions flow through once the receptors bind and which mechanism of action is used?
5HT3 is a ligand-gated receptor allowing Na+ and K+ ions to flow through when its receptors are bonded. It set an excitatory action potential.
What is the most common side effect of the 5HT3 receptor agonist drugs? what is most commonly used to combat those side effects?
5HT3 agonist drugs such as volatile anesthetics usually cause N and V. 5HT3 antagonist drugs such as ondansetron and metoclopramide are usually used to combat the N and V.
Characteristics of Nicotinic Receptors?
1) Activated by ACh and allows passage of Na+ ions
2) Inhibited by volitiles
3) Neuronal type acts at CNS ganglia (plays role in amnesia w/volatiles)
4) Neuromuscular type act at NMJ (affected by muscle relaxants).
Types of cell junctions?
1) Desmosomes - Holds cells together by continuous bands.
2) Tight Junctions - Barriers to diffusion
3) Gap Junctions - Communicating channels (requires cells to be in physical contact with each other.
Where are Gap Junctions located?
In the heart
What are the 3 ways cells communicate with each other?
1) Contact signaling by plasma membrane-bound receptors using a hydrophilic signaling molecule.
2) Remote signaling by scripted molecules using a small hydrophobic signal molecule.
3) Contact signaling via gap junctions.
6 Ways in which cells receive chemical signals?
1) Contact dependent
2) Paracrine - (i.e. interleukins and histamines).
3) Autocrine - Secreting cell targets itself
4) Hormonal
5) Neurohormone Secretion - (i.e. ADH)
6) Neurotransmitter
