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
What are extracellular messengers?
Extracellular messengers aka first messenger a substance outside the plasma membrane that bind receptors, which open or close specific channels and transfers a signal to intracellular messengers aka 2nd messengers.
What is a Second Messenger?
An intracellular enzyme that triggers a cascade of intracellular events (i.e. cAMP)
2 examples of Neurotransmitters that are 2nd messengers?
1) Epinephrine (adrenergic receptors)
2) Acetylcholine (muscarinic receptors)
Examples of Hormones that are 2nd messengers?
ACTH, ANP, CRH, Hcg, FSH, Glucagon, LH, MSH, PTH, TSH
6 steps of the cAMP 2nd messenger system?
1) First messenger binds receptor
2) Activation of G-protein intermediary
3) Activation of adenylyl cyclase
4) ATP converted to cAMP
5) cAM-dependent protein kinase phosphorylates proteins.
6) Altered protein shape bring about cellular response
6 steps of Calcium 2nd messenger System
1) Extracellular messenger binds to receptor
2) Activation of G–protein intermediary
3) PIP2 (plasma membrane component) converted to DAG and IP3 by phospholipase C
4) Release of calcium from organelles
5) Activation of calmodulin induces proteins to change shape
6) Altered proteins bring about cellular response
(T/F?) Cellular metabolism provides the cell with energy?
True - Metabolism = Anabolism + Catabolism
Define Anabolism and Catabolism
1) Anabolism is “building” and uses energy
2) Catabolism is breaking down and releases energy
What can readily diffuse through the lipid bilayer?
1) Small uncharged molecules like H2O, urea, and glycerol
2) Hydrophobic molecules such as CO2, O2, and steroids.
How do proteins move molecules through the lipid bilayer?
Via facilitated diffusion or active transport
What kind of molecules are transported across a membrane via proteins?
Large molecules such as glucose and sucrose, and Ions such as Na+, HCO3-, K+, and Mg++
Difference between Uniport, Symport and Antiport?
Uniport - one molecule at a time in one direction only.
Symport - More than one molecule at a time but all in the same direction
Antiport - More than one molecule at a time and in both directions
Characteristics of Active transport?
1) Moves molecules against a concentration gradient
2) Requires energy
3) Is protein mediated
4) Sodium-Potassium pumps
Characteristics of Sodium-Potassium Pumps?
1) Moves 3 Na+ out for every 2 K+ in
2) Antiporter (Moves 2 different ions in different directions at the same time).
3) ATPase structure (requires ATP to function)
4) Helps maintain resting membrane potential
Define Vesicular Transport?
To transport using membrane-enclosed vesicles
Endocytosis vs. Exocytosis
1) Endocytosis - Taking in (i.e. phagocytes like macrophages and neutrophils bring bacteria in).
2) Exocytosis - Expelling or releasing of contents of a vesicle.
What is Pinocytosis?
A type of Endocytosis that involves ingestion of the ECF and its contents.
What are the four phases of the cell cycle?
1) G1 (Gap) phase - Period between the M-phase and DNA synthesis.
2) S (synthesis) Phase - DNA is synthesized in the nucleus
3) G2 Phase - RNA and protein synthesis occurs
4) M phase - Mitosis (includes both nuclear and cytoplasmic division.
In which Phase of the cell cycle are errors detected?
In the G1 and G2 phase. Also, in the G1 phase the cell cycle can be arrested if errors are detected.
In which cell cycle is the spindle assembly checkpoint? What happens at this checkpoint?
M phase - Chromosome attachment to spindle is check and arrested if necessary.
What are the Phases of Mitosis?
1) Prophase
2) Prometaphase
3) Metaphase
4) Anaphase
5) Telophase
6) Cytokinesis
What are the 4 types of tissues?
1) Epithelial
2) Connective
3) Muscular
4) Nervous
General features of Epithelial Tissue?
1) Arranged in sheets
2) Densely packed
3) Has many cell junctions
4) Are attached to a basement membrane
5) Is avascular but does have a nerve supply
6) Mitosis occurs frequently
What are the 3 types of arrangement of layers of Epithelial cells?
1) Simple
2) Pseudostratified
3) Stratified
What are the 3 cell shapes of Epithelial cells?
1) Squamous
2) Cuboidal
3) Columnar
How are the covering and lining of epithelial tissue named?
They are named based on the specific shape of the cells and their arrangement.
Define a gland?
A gland is a single cell or a mass of epithelial cells adapted for secretion.
Endocrine vs. Exocrine gland?
1) Endocrine - secretes its products, for example hormones, directly into the blood.
2) Exocrine - gland secretes its products for example enzymes, into ducts that lead to the target tissue.
3 examples of multicellular glandular epithelium?
1) Sweat glands
2) Oil glands
3) Salivary glands
3 functional classifications of glandular epithelium?
1) Merocrine - secretes product
2) Apocrine - secretes part of cell
3) Holocrine - secretes whole cell
Give examples of the locations of Simple Squamous Epithelium and its function?
Location - Lining of the heart, blood vessels, and lymphatic system. Also found in the sacs of the lungs and in Bowman’s capsule.
Function - Filtration of kidneys, diffusion of oxygen into blood vessels and lungs.
Give examples of the location of Simple Cuboidal Epithelium?
Kidney tubules and ducts of many glands
Give an example of the location of Noncilliated Simple Columnar Epithelium?
GI tract
Give an example of locations Stratified Squamous Epithelium?
Skin and many wet surface such as lining of mouth and esophagus.
Where are Connective Tissue Extracellular Matrix located and what are they composed of?
Located in the spaces between connective tissue and are made of fibers and ground substance.
3 Types of Connective Tissue Fibers?
1) Collagen - strong
2) Elastic - stretchy
3) Reticular - medium stron and medium stretchy
What is the Extracellular Matrix Ground Substance?
It is a meshwork of fibrous proteins in watery, gel-like substance of complex carbohydrates. I.e. collagen, elastin, fibronectin.
What are the classifications of connective mature tissue?
1) Loose
2) Dense
3) Cartilage
4) Bone
5) Blood
What are Membranes?
Membranes are flat sheets of pliable tissue that cover or line a part of the body. i.e.:
What are some examples of Membranes?
1) Epithelial Membranes - Mucous membranes, serous membranes, and cutaneous membranes
2) Synovial Membranes
Examples of locations of Elastic Connective Tissue?
Lungs (recoils in exhaling) and arteries (recoil between heartbeat)
Example of Reticular Connective Tissue Function?
Filters and removes microbes in lymph nodes
Example of location of Hyaline Cartilage?
Trachea, bronchi, and bronchial tubes. Also, at the end of bones and joints.
Examples of Mature Connective Tissue?
Bone and blood
General characteristics of Muscular Tissue?
Consists of fibers that provide motion, maintain posture, and produce heat.
3 types of Muscular Tissue
1) Skeletal
2) Cardiac
3) Smooth
Examples of location of Smooth Muscular Tissue
In the walls of hollow internal structures such as blood vessels, airway to lungs, stomach, intestines, gallbladder, urinary bladder and uterus.
2 kinds of Nervous tissue?
Neurons and Neuroglia (protect and support neurons)
Characteristics of Nervous Tissue?
1) Consists of a cell body, dendrites, and axons
2) Carry sensory and motor information
3) Perform integrative functions
What are Histones?
Proteins in the nucleus that bind DNA and help regulate its activity.
Some cells such as Neutrophils synthesize Hydrogen Peroxide and use it as a defensive weapon. Where is this Hydrogen Peroxide synthesis
In their Peroxisomes
What is s Lipid Raft?
A section of a membrane that is rich in cholesterol and helps to organize membrane proteins.
Define Fibroblasts?
Cells that secrete extracellular matrix.
What is Hydrostatic Pressure?
The mechanical force of water pushing against cellular membranes
A _________ solution, has the same osmolality as normal body fluids.
Isotonic
In a simple epithelium, the cells are in contact with a _________ membrane that provides support.
Basement
What kind of tissue is characterized by only a few cells surrounded by a lot of extracellular matrix?
Connective Tissue
What is a myocyte?
A kind of muscle cell
What are the sequence of actions that occur in a neuronal muscle cell?
1) Sodium permeability increases
2) Sodium ions move into the cell
3) Potassium permeability increases
4) Potassium ions leave the cell
5) Resting membrane potential is re-established.
What is the main difference between cells that divide rapidly and those that divide slowly?
The amount of time spent in the G1 Phase
Cells develop specialized function via which process?
Differentiation
Difference between a solute and a solvent?
1) Solute - A particle that is dissolved
2) Solvent - A medium in which a solute is dissolved in.
The Mitochondria need a lot of _____ to function?
Oxygen
What are Paracrine signals?
Signals that act on nearby cells via diffusion through interstitial fluid.
Cell that has insufficient oxygen supply will not be able to perform the chemistry of which cycle?
Krebs Cycle
What is a Ligand?
A substance that binds to a receptor
What is a Caveolae?
Tiny flask-shaped pits in the outer surface of the plasma membrane that may be important locations for receptors or for entry into the cell.
If the ECF becomes hypotonic, in which direction will water move?
From ECF into the cell
If the concentration of substance X in the ECF is higher than its concentration inside the cell, in which direction will active transport move substance X.
From the cell to ECF
If the glucose concentration in the ECF is higher than its concentration inside its cell, in which direction will facilitated diffusion move glucose?
From ECF into the cell
In which direction does Na+ K+ ATPase move SODIUM ions
From the cell to the ECF
In which direction does Na+ K+ ATPase move POTASSIUM ions
From ECF into the cell
A mutation affecting what function would cause a lysosomal storage disease?
One that affects lysosomal enzymes will allow items that cannot be digested to accumulate inside lysosomes, creating a lysosomal storage disease.
How does the presence of gap junctions in cardiac muscle facilitate cardiac function?
Gap junctions synchronize contractions of heart muscle cells through ionic coupling.
Explain why intracellular receptors do not use 2nd messengers, but many cell surface receptors do.
Cell surface receptors use 2nd messengers because the ligand (1st messenger) cannot enter the cell. Intracellular receptors do not need 2nd messengers because the ligand enters the cell.
What happens during the interphase portion of the cell cycle? Why are those events important?
During interphase (G1, S, and G2 phases), the cell increases its mass by producing DNA, RNA, protein, lipids, and other substances, and duplicates its chromosomes. These processes are necessary to prepare the cell for mitosis and cytokinesis.
