Exam 1 Week 1 Flashcards
Mileu Interiuer:
Internal environment of multi-celled organisms that requires homeostatic mechanisms to be maintained
_______ is the study of homeostatic mechanisms.
Physiology
ECF makes up ______ of the total body water, and is composed of ______(1/4) and _____(3/4). ICF makes up _____ of the total body water.
- ECF = 1/3 total
- Plasma (1/4)
- Interstitial Fluid (3/4)
- ICF = 2/3 total
Movement from Plasma to ISF to ICF is primarily dependent on ______.
Na+ concentration
Normal plasma osmolarity is about ________.
290mEq/L
Differentiate between Equilibrium and Steady State:
Equilibrium is when there is no net flux of energy required for Compartment 1 = Compartment 2. Steady State may require energy input to maintain a SET POINT.
A shift in set point triggers ______, which act by 3 mechanisms: ____, _____, and ____.
- Effectors
- Neg. Feedback
Pos. Feedback
Feed Forward
Feed-Forward mechanisms amplify the initial disturbance in set point, but MUST have _________. An example of this is: ______.
- An Endpoint
2. FSH/LH release up until ovulation begins.
Set-Point deviations are caused by what 2 things?
Give 3 examples: _______.
- Circadian Rhythms
- Environmental Changes
Ex. 1: Moving to high altitude changes the set point for PCO2.
Ex. 2: Fevers increase temperature set point to reduce viral replication.
Ex. 3: Plaque dev. over time increases the set point for B.P. leading to heart failure.
Define Redundancy:
Give an example: ____.
Having an alternate mechanisms for control of a variable if the primary mech. should fail.
Ex: Blood Pressure Control:
- Primary = Baroreceptors
-Secondary = R.A.A.S.
Describe “Hierarchy” in terms of physiology:
Some variables are more important to control so set points of others will be altered to prevent a change in a more significant variable.
Deficient Homeostatic Mechanisms:
Give an example: ______.
When negative feedback loops become positive feedback loops and actually worsen symptoms of an illness.
Ex: Heart failure = Decreased C.O.
So we increase fluid retention which increases preload to the heart and causes further congestion.
Which of these is NOT a homeostatic controlled variable?
- Arterial PO2
- Blood Glucose
- pH
- B.P.
- Heart rate
Heart Rate. It is actually an effector used to control blood pressure.
Difference between Osmolality and Osmolarity:
Osmolality = mOsmoles/kg Osmolarity = mOsmoles/ L
Simple diffusion can be accomplished 2 ways:
- Readily crossing the membrane
2. Flowing through OPEN channels
The 2 types of Carrier-Mediated diffusion are:
- Facilitated Diffusion: Using channels/proteins
2. Active Transport: Primary uses energy directly (ATP), while secondary uses energy indirectly (Na+).
What law explains simple diffusion and how flux causes flow? (And also describes how equilibrium is reached)
Fick’s Law
What does a partition coefficient GREATER than 1 mean? Less than 1?
P>1 = Lipophilic, Passes through membrane EASILY P<1 = Hydrophilic, does not pass easily
What does a reflection coefficient close to 1 mean? Close to 0?
1 = DOESN'T pass through membrane 0 = Passes through membrane
When would Fick’s Law use the Partition Coefficient rather than the Diffusion Coefficient to calculate Flux?
When the thickness of the membrane is known
Differentiate between…
Pore: _______
Channel: ______
Transporter: ______
Pore: ALWAYS open (non-gated channel)
Channel: Open/Close (gated)
Transporter: Undergoes Conformational Change
What 4 factors determine the rate of ion transport?
- Saturation of Transporters
- # of transporters
- Time for Conformational Change
- Concentration Gradient
What is the most common example of secondary active transport?
Use of the Na/K-ATPase (or other exchangers/co-transporters) to utilize the electrochemical gradient.
Describe Receptor-Mediated Endocytosis: (4 steps)
- Ligand binds receptor
- Recruits adaptor proteins and Clathrin
- Forms lattice for invagination
- Dynamin/Other proteins assemble/disassemble to pinch off the vesicle.
Describe Paracellular Transport:
Movement between “leaky” tight junctions of adjacent EPITHELIAL cells lining hollow organs.
Describe the main channels involved in Absorption and Secretion respectively:
Absorption: eNaC channels: Na+ INTO cell, then plasma.
Secretion: CFTR channels: Cl- OUT to lumen.
The cell membrane is ___% lipids and ___% proteins.
50:50
Integral Membrane Proteins can be either _____ or _____. There are also 6 types: ______.
- Transmembrane or Anchored
- The 6 Types Are:
- Pumps/Carriers/Transporters
- Channels (Pores)
- Receptors
- Linkers
- Enzymes
- Structural Proteins
What is “asymmetry” and why is it important?
- Expression of certain phospholipids ONLY on the inner or outer leaflet of the membrane.
- It allows the cell to dynamically rearrange some if needed for signaling:
Ex: PhosphatidylSerine can move from inner to outer to signal macrophages of apoptosis.
Lipid Rafts are enriched with ______.
Cholesterol
The carbohydrate-rich region on the cell surface is called the _______. It contains: (3) _____.
- Glycocalyx
2. Glycolipids, Glycoproteins, Proteoglycans
What is the function of the glycocalyx?
Mainly protective, but also involved in binding.
Exocytosis can be either _______ or ______. (Describe Both)
- Regulated: SECRETORY cells store substances at the membrane and release them upon stimulation.
- Constitutive: Continuous delivery of a substance without stimulus being needed.
In receptor-mediated endocytosis, the ligand and receptor can either both de degraded, recycled, or one can be saved while the other is degraded. What is the 4th possible fate?
Transcytosis: Both are simply moved to the other side of the cell and released for other utilization.
Functions of Early and Late Endosomes respectively:
- Early: Recycle/Degrade the receptor and ligand.
2. Late: Trafficking of endocytotic materials.
Endocytotic substances move from the ____ to the _____ and finally to the ______. Along this pathway, these structures will exhibit what change?
- Early Endosome –> Late Endosome –> Lysosome
2. pH becoming more Acidic
Pinocytosis:
“Cell-Drinking”, specialized for small endocytotic events
A dynamic change in potential that occurs over time is called ______.
An Action Potential
Describe Charge Equivalence:
Any biological solution has an equal amounts of positive and negative charges.
Resting Membrane Potential:
Separation of charges across the membrane that allows development of an electrochemical gradient.
Conductance:
RECIPROCAL of resistance. Requires more/open/bigger channels to alter membrane potential.
Which ion will have the greatest influence on membrane potential in a cell?
The one with the highest conductance.
i.e. Most/Biggest channels to allow movement across the membrane.
List the 4 requirements of Resting Membrane Potentials:
- Concentration Gradient across membrane (set up by Na/K-ATPase)
- Channels (Path for charge flux)
- Channels must OPEN
- RMP is set by ion with highest conductance
What equation is used to calculate the equilibrium potential of an ion?
The Nernst Equation
Differentiate between membrane potential and equilibrium potential:
Vm = Can't be calculated, only measured. It is the net effect of ALL ion movement. Em = Calculated for a SINGLE ion species.
How is driving force calculated?
Em - Vm = Driving Force
_______ is essentially a term used to describe the fractional conductance of each ion across a membrane.
Permeability (represented as a value from 0-1)
What ion has the strongest inward driving force?
Ca2+
Cl- has a conc. of 50mM INSIDE the cell and about 120mM OUTSIDE the cell. Explain why the driving force for Cl- movement is still IN to the cell:
The ratio of 50/120 gives Chloride an Ecl = -22.8mV. Therefore, it wants to make the inside of the cell negative. Since Cl is a NEGATIVELY charged ion (anion), it must move inward to accomplish this.
What are the units for conductance?
Amps/Volts
Differentiate between Absolute and Fractional Conductance:
Absolute: Refers to a single ion’s conductance
Fractional: Refers to the % of the total conductance that a specific ion holds
*Only change in fractional conductance will determine action potentials and change in membrane potential.
When is flux following the CHEMICAL gradient?
When is flux following the ELECTRIC gradient?
- Chemical = Vm < Em
2. Electric = Vm > Em
Zellweger Syndrome:
Defective peroxisomes due to improper Golgi trafficking
Where is the Nuclear Lamina located?
Beneath the nuclear envelope layers, continuous with the inner layer.
The Nuclear Lamina is composed of ______, which are ______.
- Laminar Proteins
2. Intermediate Filaments
What results from an improperly formed nuclear lamina?
DNA will not be protected during division and this accelerates the aging process.
Nucleolus:
The site of ribosome production, located within the nucleus.
Differentiate between Euchromatin and Heterochromatin:
Euchromatin: Less condensed, more transcriptionally active (light staining)
Heterochromatin: Tightly condensed, not very transcriptionally active (dark staining)
Where is heterochromatin found?
Along the periphery of the nuclear envelope
During apoptosis, where is DNA cleaved?
At linker regions between nucleosome histone octets
When is heterochromatin the most condensed?
During the metaphase of mitosis
Centromere:
The center of heterochromatin
List the 4 destinations of proteins that are produced on FREE ribosomes:
- Nucleus
- Mitochondria
- Peroxisome
- Cytosol (Cytoplasm)
Compared to the R.E.R., the Smooth E.R. is more ______, and exhibits ______ on a microscopic image. The smooth E.R. possesses ______ for detoxification.
- Tubular
- Round/Oblong Tubes or bubbles
- Cytochrome P450’s
The Sarcoplasmic Reticulum is just the _____ of muscle cells.
Smooth E.R.
What cells would have a very LARGE Golgi?
Cells specialized in making proteins to be SECRETED.
How are proteins targeted for the lysosome?
They are tagged with Manose-6-Phosphate (M6P) which is recognized by an M6P-receptor to target them for the lysosome.
Tay-Sach’s Disease:
(Autosomal recessive) HEXA Deficiency: A lysosomal enzyme required for glycoside degradation. Accumulation leads to apoptosis and eventually tissue/organ death.
Autophagy:
Cell creates autophagosomes that engulf portions of cytoplasm to degrade old/impaired structures at the lysosome.
What types of proteins does the proteasome degrade?
What does the proteasome depend on?
- Those tagged with UBIQUITIN
2. ATP
Lipofucsin:
A pigment (brown appearance) seen in old/aging cells.
2 Functions of Peroxisomes:
- B-oxidation of F.A.’s
2. Detox of reactive O2 species
How cold the mitochondria signal apoptosis within a cell?
The could release Cytochrome C into the cytoplasm to signal its initiation.
Centriole:
9 triplets and 2 doublets of microtubules around a centrosome.
Centrosome:
Microtubule-organizing center
Microtubules are composed of ______ and have both a ______ and a ______ end.
- a/b-tubuiln dimers
- (+) Polymerizing end
- (-) Anchored end
Describe the 2 Mitotic Spindle Poisons:
- Colchicine: (Anti-cancer) Binds microtubules and prevents POLYMERIZATION.
- Taxol: (Anti-cancer) Binds microtubules and prevents DISASSEMBLY.
2 Types of Microtubule Motor Proteins:
- Dyneins
2. Kinesins
2 Types of Dyneins:
- In cytoskeleton
2. In flagella (AXONEMAL)
What is the difference between dyneins and kinesins?
Dyneins: Walk in (-) direction
Kinesins: Walk in (+) direction
What structures are dyneins and kinesins associated with?
Cilia and flagella: They walk along them and stretch/bind them to adjacent microtubules to cause movement.
i.e. Sperm Motility, Mucous Clearance, etc.
3 Components of Microtubules:
- 9 triplets of
- 2 doublets
- Dynein Arms
Intermediate Filaments are _________ structures made up of _______, and they are considered ________.
- Rope-like
- Staggered Tetramers
- Non-Polar/Structural
Where is actin located and why?
Near the Plasma Membrane in order to be used in actin polymerization for cell motility.
2 Fungi that Impair/Alter actin function:
Phalloidin/Amatoxins: Bind to f-actin and prevent its DEpolymerization.
Actin is associated with what structures? How is it associated with them?
- Microvilli and Stereocilia
2. It forms their core and they serve to increase S.A.
Differentiate between Filopodia and Lamellipodia:
Filopodia: Finger-like
Lamellipodia: Sheet-like
Describe what is meant by “actin treadmilling”:
While polymerization is occurring at the (+) end, depolymerization is occurring at the (-) end.
What is diapedesis and what cells use this process?
- Neutrophils
2. The extension of lamellipodia/pseudopodia to migrate from blood vessels into connective tissue.
Lipids have increased solubility in ________.
Organic Solvents
2 Functions of Lipids:
- Provide Energy (Stored as Triacylglycerol)
2. Form Steroids/Vitamin D
Differentiate between the 3 types of lipid classes:
- Simple: Triacylglycerols
- Complex: + a non-lipid component
- Derived: + F.A. (Mix of simple/complex)
Most F.A.’s are _______ chain fatty acids, and are named from ______ to _____.
- EVEN chain
2. Carboxyl group to Methyl Group
What is an Omega Carbon?
The terminal carbon of a fatty acid attached to the methyl group.
Short chain F.A.’s are mostly found in ______, while long chain are found in _____.
- Short = Milk
2. Long = Human Body
What 2 characteristics of F.A.’s give them more rigidity?
- Longer Chain
2. More saturated
What 2 structures primarily maintain the MOBILITY or fluidity of the membrane?
- Short chain fatty acids
2. Unsaturated fatty acids
What type of F.A. is Oleic Acid?
An Omega-9, monounsaturated F.A.
Describe the 2 Omega-6 F.A.’s found in the body:
- Linoleic Acid: O-6 with 2 double bonds, ESSENTIAL in diet (must eat).
- Arachodonic Acid: O-6 with 4 double bonds, formed from Linoleic Acid (NOT essential).
In our diet, we want HIGH amounts of ______ acids, and LOW amounts of ____ acids.
- HIGH = Omega-3
2. LOW = Omega-6
What type of F.A. is alpha-linolenic acid? What is it converted into?
- An Omega-3 ESSENTIAL fatty acid
2. EPA and DHA
What are EPA and DHA and what are their functions?
- Eicosanoids
- EPA–>Cardioprotective/Anti-Inflammatory
DHA–>Brain Dev./Vision
What is another name for a gylcerol esterified with 3 F.A.’s?
Triacylglycerol = Simple F.A.
Triacylglycerol is very _______, therefore it is never located _______, but rather it is ONLY _______.
- Hydrophobic
- In the plasma membrane
- Stored as energy
What are the 2 types of complex lipids?
- Phospholipids
- Glycolipids
* i.e. Have a non-lipid component*
What types of lipids are amphipathic and therefore found in the membrane?
Complex lipids
Although double bonds in unsaturated F.A.’s help maintain membrane fluidity, what is a potential problem they cause?
Their double bonds increase the chance of them being damaged and creating reactive oxygen species.
Components of a Glycerophospholipid:
- Glycerol with:
- ->Saturated F.A.
- ->Unsaturated F.A.
- ->Phosphate (Head Group)
List the 4 main glycerophospholipids:
Also, which is most abundant?
- -PhosphatidylSerine
- PhosphatidylInositol
- PhosphatidylCholine
- PhosphatidylEthanolamine
- Most Abundant = Phosphatidylcholine (Lecithin)
Where are each of the 4 main glycerophospholipids found?
- Lecithin: Mostly in the OUTER leaflet of the plasma membrane
- All other 3: INNER leaflet of the p.m.
Where is Cardiolipin found?
ONLY in the inner mitochondrial membrane (NOT in the heart)
Give the 2 types of phospholipids with ETHER linkages instead of Ester linkages at C-1:
- Plasmalogens
2. PAF: Platelet-Activating Factors
Name and give the structure of DPPC:
- DiPalmitoyl PhosphatidylCholine
- Glycerol with:
- ->Saturated F.A.
- ->Saturated F.A.
- ->Phosphate (Head Group) - Choline
How does DPPC differ from Lecithin?
It has 2 saturated F.A.’s instead of one sat. and one unsat.
Function of DPPC:
Pulmonary Surfactant production: Protects alveoli from collapsing.
What value can you test for to determine if there is proper development of the fetal lung? Describe what values indicate:
- Lecithin-Sphingomyelin Ratio
- Values>2 = Mature, good development
- ->Values<1.5 = Risk of alveoli collapse
If the Lecithin-Sphingomyelin ratio is too low, how can we accomodate the fetus?
Artificial surfactant containing DPPC
What is the only important sphingophospholipid?
Give its components:
- Sphingomyelin
- Sphingosene with:
- ->(branch of same sphingosene)
- ->F.A.
- ->Phosphate (Head Group)
What is another name for glycolipids and why?
- Sphingoglycolipids
2. They ALL have sphingosene as the alcohol component
List the 4 types of Sphingoglycolipids:
- Cerebroside
- Sulfatide
- Globoside
- Ganglioside
Where are sphingoglycolipids found? Why is this important?
- ALL in the OUTER leaflet only
2. They form the glycocalyx
What is the glycocalyx?
A carbohydrate sheath around the cell
What is the difference between Sphingomyelin and Sphingoglycolipids?
Sphingomyelin is a sphingophospholipid, so it has a phosphate group where sphingoglycolipids would have a carbohydrate (sugar) group.
Structure of Ceramide:
Sphingosene + F.A.
i.e. Backbone of sphingophospholipids and sphingoglycolipids
Give the components of each of the 4 types of sphingoglycolipids:
- Cerebroside: Ceramide + Monosach.
- Sulfatide: Ceramide + Monosach. + Sulfate
- Globoside: Ceramide + Oligosach.
- Ganglioside: Ceramide + Oligosach. containing NANA
Give the 2 main components of the Myelin Sheath:
- Sphingoglycolipids
2. Sphingophospholipid (Sphingomyelin)
2 Components of Cholesterol:
- Steroid Ring
2. Hydrophobic Chain
Cholesterol is a precursor for steroids, vitamin D, AND _____.
Bile Acid/Bile Salts
What is Dalton’s Law?
The total pressure of a gas mixture is equal to the sum of the partial pressures of each gas involved.
Describe how the fractional concentration of a gas and the barometric pressure are associated with increasing/decreasing the partial pressure of that gas:
- Fractional Concentration NEVER changes
i. e. O2 is ALWAYS 21% of atm. - Higher altitude = DECREASED Barometric Pressure, which means DECREASED PO2.
What is Henry’s Law? What conditions does it assume?
- Amount of Gas Dissolved = Ks x Pp
Ks: Solubility Constant
Pp: Partial Pressure - It is used for gases dissolved IN LIQUID
Water wants to move from ______ solute conc. to ______ solute conc. This can be sped up by ______.
- LOW–> HIGH
* To bring down the high solute conc.* - Aquaporins
2 Major Forces that drive water movement:
- Osmosis
2. Hydrostatic driving force
What is the Vant Hoff Equation:
Osmotic Pressure = nRTC
- ->Pi = Osm. Press.
- ->n = # of particles
- ->R = Gas Constant
- ->T = Temp
- ->C = Concentration
Give the equation for WATER flux:
Jw = K1 x A [ r(C1-C2)]
- ->K1 = Diffusion coeff. of water
- ->A = Surface Area
- ->r = Reflection coeff.
Difference between osmolarity and tonicity:
Osmolarity: TOTAL CONC. of all particles in a solution
Tonicity: Conc. of IMPERMEABLE ions only
What do the osmolarity and tonicity describe respectively?
Osmolarity describes water movement up until equilibrium, tonicity describes water movement AFTER equilibrium is reached.
In what direction will water move in a hypo-/hyper-tonic solution.
- Hypo: Water IN
- Hyper: Water OUT
i. e. Water goes to HIGH tonicity
Give 3 Examples of substances that WILL penetrate the membrane:
- Glucose
- Urea
- Glycerol
What solutions of Saline and Dextrose are Hypo-, Iso-, and Hyper-tonic respectively?
- ->Hypo:
- 0.45% Saline
- 5% dext. in H2O
- ->Iso:
- Ringer’s Sol.
- 0.90% Saline
- 5% dext. in 0.225% Saline
- ->Hyper:
- 3.0% Saline
- 5% dext. in 0.45% Saline
- 10% dext. in H2O
What is an Omega F.A.?
An F.A. that is named from the METHYL end because it’s first double bond is closest to that end
What kind of lipids are saturated lipids? What does this mean?
- DERIVED lipids
2. They are made biologically, non-essential
What are the 2 types of Eicosanoids? What precursor are they formed from?
- Prostaglandins
- Leukotrienes
Formed from ARACHADONIC ACID
Why are trans-fats bad?
In the trans- conformation, they DON’T have kinks in their structure, so they LIMIT membrane fluidity and stiffen the membrane. In this way, they increase the risk of HEART DISEASE.
How can sphingoglycolipids be used to trigger apoptosis?
PhosphatidylSerine can move from the inner leaflet to the outer leaflet and be recognized as an apoptosis signal.
Why is PhosphatidylInositol important?
It is cleaved to form PIP2, which is utilized in the IP3/DAG pathway.
Function of Lipid Rafts:
Signal transduction: They move freely in the membrane, but also allows viruses into the cell.
What is the MAIN determinant of membrane fluidity?
FREE cholesterol
Where are each of the 5 Glut-transporters found?
Glut 1: RBC's, B.B.B., Kidneys Glut-2: "PIKL" Pancreas, Intestines, Kidney, Liver Glut-3: Brain and Neurons Glut-4: "HAM" Heart, Adipose, Muscle Glut-5: Intestinal Lumen
Which Glut-transporters are HIGH and LOW affinity?
High: Glut-1, 3, and 4
Low: Glut-2 and 5
Describe the role of Glut-5:
Uptake of dietary FRUCTOSE, and release of its into the seminal vesicles for seminal energy.
What MUST an ion have to maintain driving force?
CONDUCTANCE: Must have OPEN channels or the gradients don’t matter.
What do points “4” and “5” on an A.P. diagram represents in terms of K+ conductance?
“4” = Highest ABSOLUTE conductance
since it has even more channels open
“5” = Highest FRACTIONAL conductance
since it has the ONLY channels still open
What are the alternative names for the 2 gates of a voltage-gated sodium channel?
Inactivation Gate: “H”-gate
Activation Gate: “M” gate
Describe the movement of the H and M gates during each step of an A.P.:
- Only H-Open
- H-Open, M-Open
- Only M-Open
- Only H-Open
Describe how Hypo- and Hyper-kalemia make A.P.’s less possible in the cell:
- Hypo: Too far from threshold for A.P.’s to occur easily
2. Hyper: Can’t HYPERpolarize (won’t fire again)
Define Resolution:
What 2 things is it dependent on?
Resolution: Ability to distinguish between 2 objects
- Wavelength
- Energy source
Does light microscopy or electron microscopy have higher resolution?
Electron Microscopy
What form of microscopy is H&E a common stain for?
Light Microscopy
List the 5 steps of Tissue Preparation:
- Fixation
- Dehydration
- Embedding
- Sectioning
- Staining
Give the 2 most common fixatives for light and electron microscopy respectively:
- -> Light:
1. Formaldehyde
2. Formalin - -> Electron:
1. Glutaraldehyde
2. Osmium Tetroxide (Lipid fixation)
Differentiate between osmium tetroxide and sudan black:
Osmium Tetroxide is a FIXATIVE for lipids, while Sudan Black is a DYE for staining lipids.
How is dehydration accomplished?
Via a series of alcohol solutions with increasing acidity.
Give the most common embedding agents for light and electron microscopy respectively:
- -> Light:
1. Paraffin - -> Electron:
1. Epoxy Resin
What is Silver Stain used for?
Staining Reticular Fibers in CONNECTIVE tissue
What is PAS? What is it used for?
Periodic Acid -Schiff: Stains 4 CARBOHYDRATE things…
- Glycogen
- Mucous
- Basement Membranes (proteoglycans)
- Reticular Fibers (proteoglycans)
Differentiate between the 2 types of Trichrome Staining:
- Mallory (Blue) Trichrome: Stains connective tissue blue
2. Masson (Green) Trichrome: Differentiates smooth muscle from connective tissue (teal/green stain).
Differentiate between the 2 types of electron microscopy:
- (TEM) Transmission E. Mic: Beam passes THROUGH the sample on slide. (Shows organelles)
- (SEM) Scanning E. Mic: Beam is REFLECTED off surface of sample on slide. (Shows surface structures)
Differentiate between the 2 types of Immunohistochemistry:
- Polyclonic: Mix of antibodies targeted against multiple antigens.
- Monoclonic: Mix of antibodies targeted against a single antigen.
Antibodies are considered _______, and there are 5 classes: _______.
- Immunoglobins
2. Ig..”G.A.M.E.D.”
What do “H” and “E” dyes stain for respectively?
- H stains for: DNA/RNA (phosphate of nucleic acid)
2. E stains for: Proteins (amino group)
What structure on the outside of the cell causes the outer region of the membrane to stain PINK in an H&E stain, compared to the intracellular region staining purple?
Collagen Fibers
What stain do we use on Lipids and why?
- PAS
- Since lipids don’t fix/stain well with water.
We use:
Fixative: Osmium Tetroxide
Dye: Sudan Black
Differentiate between the 2 types of Trichrome staining:
Mallory stains connective tissue BLUE, while Masson stains connective tissue GREEN/TEAL and differentiates it from smooth muscle.
What is the primary limitation of electron microscopy?
Can’t stain samples, images are only black and white
How can size of a cell be used as an indication of its level of activity?
Taller cells are more active
What does the modified fluid mosaic model take into account that the original model doesn’t?
Lipid Rafts
Composition of Lipid Rafts: (3)
What is their function?
- Cholesterol
- Glycosphingolipids
- Sphingomyelin
Function: Signal Transduction
Main components of the OUTER leaflet of the bilayer:
- Phosphatidyl Choline
- Sphingomyelin
- Phosphatidyl Ethanolamine
- Glycosphingolipids (GLYCOCALYX)
Main components of the INNER leaflet of the bilayer:
Which are also found in the inner leaflet?
- Phosphatidyl Ethanolamine
- Phosphatidyl Serine
- Phosphatidyl Inositol and PIP2
- Phosphatidyl Choline
* ONLY ethanolamine and choline are also in the INNER*
What forms the glycocalyx?
Glycolipids and glycoproteins, NOT glycosphingolipids (those are in the inner membrane)
2 Main factors determining membrane fluidity:
- F.A. composition
2. Cholesterol amount
Describe where cholesterol is found and how it influences membrane fluidity:
- Found in BOTH layers (binds near space created by CIS-double bonds)
- DECREASES fluidity at polar head
INCREASES fluidity at F.A. component
How does cholesterol prevent drastic changes in fluidity caused by temperature?
- COLD TEMP: Cholesterol intercalates between F.A.’s to give more fluidity
- HOT TEMP: Cholesterol steroid ring system slows down movement of F.A.’s to lower fluidity
How is regulation of fluidity maintained in other membranes WITHIN the cell?
They DON’T possess cholesterol, so the main determinant is F.A. composition.
What is the function of cardiolipin and where is it found?
- Inner Mitochondrial Membrane
2. Makes it less permeable
Describe the structure and function of Lipoproteins:
- Structure: Phospholipid MONOLAYER that contains FREE cholesterol.
- Function: Transport of Non-polar Lipids
What are the 2 Non-Polar Lipids transported by Lipoproteins?
- Triacylglycerols
2. Cholesteryl Esters
How does F.A. chain length affect membrane fluidity? Give 2 main examples: ______.
- Longer Chains = More RIGIDITY
2. Arachidonic Acid and DHA are short chain F.A.’s that INCREASE fluidity very well.
How would the rate of transport of the 2 different types of Passive Diffusion appear different on a graph?
- Simple: Linear, because there is no Vmax.
2. Carrier-Mediated: (Facilitated Diff.) Hyperbolic, because channels can become saturated and reach Vmax.
Why is GLUT-1 abundant in RBC’s?
Because they lack mitochondria and always need to conduct glycolysis for energy.
Where is GLUT-4 stored and how is it mobilized?
- Stored in ENDOSOME
- Mobilized by:
a. ) Insulin (all targets)
b. ) Exercise (muscle)
What condition can insulin injection cause?
HYPOglycemia: Due to rapid uptake of glucose into muscle and fat.
How do the B-cells of the pancreas know when to release insulin?
Glut-2 in the liver releases glucose through the blood to them and they detect blood glucose increase.
What does GLUT-1 deficiency cause? What 4 conditions will those affected develop?
- Metabolic Encephalopathy (Microcephaly and Seizures)
- Symptoms:
- ->Ataxia
- ->Delayed psychomotor dev.
- ->Movement disorders
- ->Impaired speech
What type of transport allows the uptake of dietary glucose/galactose and how is it accomplished?
- Secondary Active transport
- SGLT-1: Symporter that moves Na+ and Glucose into INTESTINAL MUCOSAL cells. Accomplished via the NA/K-ATPase activity.
How might a drug be designed to inhibit the uptake of dietary glucose/galactose?
Inhibit the SGLT-1 Na/K-ATPase activity
What do all ABC transporters do and what are they? Give an example: _________.
- ATP-Binding Cassete Transporters
- Move molecules from CYTOSOL to ECF using ACTIVE transport (ATP hydrolysis)
- Liver: Moves bile salts and bilirubin into bile ducts
How is the CFTR different from other ABC transporters?
It ISN’T a real ABC transporters. It has an ABC, but is really a channel that only needs 2 ATP initially to open it, then millions of Cl- ions can flow through freely.
i.e. Not REAL active transport
In what type of cells and where are CFTR’s present?
- Epithelial Cells
- “PAIRS”
- Pancreatic Ducts
- Airway Ducts
- Intestinal Lumen
- Reproductive Ducts
- Sweat Glands (Skin)
What does failure of CFTR function cause?
It prevents the movement of WATER with those chloride ions, so bacteria can cause infection
(Stool = hard, skin = salty, etc.)
What does CFTR stand for?
Cystic Fibrosis Transmembrane-conductance Regulator
How do CFTR’s attract water?
Cl- passes through duct, BINDS with Na+ from the interstitial fluid on the way, and forms NaCl which attracts water outward with it.
How are CFTR’s different in the sweat glands? Why is this important?
- They direct Cl- ions INTO the epithelial cells, since NaCl conc. is higher outside. Thereby making the sweat/skin less salty.
- Importance: Sweat tests for conc. can be conducted to diagnose CF.
Define Sarcoma and Carcinoma:
- Carcinoma: Epithelial malignant tumor
2. Sarcoma: Connective Tissue malignant tumor
What types of tissue do sarcomas affect?
- Muscle
- Adipose
- Cartilage
- Bone
- Tendons
What is the most common type of cancer? Give 2 reasons why: __________.
- Carcinoma = 90% of all cases
- Two Reason:
- ->Rapidly Renewing (mutations in division)
- -> Exposed frequently to damage
Describe the 2 possible ways that tumors form initially:
- Clonal Evolution: Dev. through repeated rounds of proliferation with mutations. Cells gain growth advantage over normal cells.
- Stem Cell Evolution: Tumors contain cancerous stem cells, divide indefinitely, and are linked to LEUKEMIAS.
What 2 things do malignant tumors cause that increase genetic instability long term?
- Aneuploidy
2. Chromosome Translocations
Define Aneuploidy:
Abnormal number of chromosomes
What are the 2 major mechanisms of cell death?
- Necrosis
2. Apoptosis
Characteristics of Necrosis: (5)
Caused By: ______.
- Pathological
- Cell unable to maintain homeostasis
- CELL SWELLING
- Loss of membrane integrity
- Surrounding tissue damage/Inflammation
Cause: Acute Cell Injury
Characteristics of Apoptosis: (5)
Caused By: _______.
- Physiological
- Programed cell death
- CELL SHRINKING
- Membrane remains intact
- No surrounding damage/no inflammation
Cause: Genetic
What does cell shrinking eventually lead to in apoptosis?
Formation of blebs of cell membrane that pinch off and are degraded.
Differentiate between Normal and Abnormal Tissue Homeostasis:
- Normal: Intended for cells that undergo renewal regularly and are replaceable.
- Abnormal: Loss of non-renewing cells
Describe Extrinsic Apoptosis: (4)
- Ligand binds to Death receptor (on SURFACE of cell)
- Recruits death domain adaptor proteins
- Forms death-inducing signal complex
- Caspase cascade
Describe Intrinsic Apoptosis: (5)
- Death Signal occurs (ex: DNA damage)
- Pro-apoptotic proteins UPREGULATED
- Release of Cyt. C from mitochondria
- Cyt. C helps form APOPTOSOME
- Caspase Cascade
Caspases:
A family of proteases that target both nuclear and cytoplasmic proteins
Give the events of each of the 2 Phases of the Cell Cycle:
- Interphase
- G1
- S (DNA synthesis)
- G2 - Mitosis
- Karyokinesis (Nucleus Division
- Cytokinesis (Cytoplasm Division)
What is the most important checkpoint in the cell cycle?
G1: Causes major DNA damage if skipped
What happens during the G1 Phase?
Cell growth, synthesizing RNA and proteins, gathering nutrients
What 2 things does the G1 checkpoint search for in dividing cells?
- DNA Damage
- Replication Potential
i. e. Is cell big enough, environment favorable?
What structures regulate the G1 restriction checkpoint?
Rb Proteins: Retinoblastoma Proteins
What happens during the S Phase?
- Sister Chromatids are formed
i. e. DNA Replication
What does the S checkpoint search for in dividing cells?
Checks for DNA damage again
What happens at the G2 Phase?
More cell growth and organization of organelles
What 2 things does the G2 checkpoint search for in dividing cells?
- DNA Damage
- Un-replicated DNA
i. e. DNA synthesis MUST be completed
What 2 things does the Mitosis checkpoint search for in dividing cells?
- M1 = Spindle-Assembly (before Anaphase)
2. M2 = Chromosome Segregation (before Cytokinesis)
Define Mitosis:
List the 5 stages:
- Somatic Cell Reproduction
- Five Stages:
- Prophase
- Prometaphase
- Metaphase
- Anaphase
- Telophase
Centromere: (2)
- Centric heterochromatin that holds sister chromatids together.
- Kinetochore site of formation.
Kinetochore:
Attaches chromosome to mitotic spindle
How are centrosomes involved in mitotic spindle formation?
Centrosomes are microtubule-organizing centers. The position of their centrioles will determine the location of mitotic spindle poles.
3 Components of the Mitotic Spindle:
- Centrosomes
- Microtubules
- Motor Proteins (Dyneins/Kinesins)
What 2 things happen during S phase?
- Replication of DNA
2. Replication of centrosome
What happens during the G2 to M transition?
Centrosomes Separate and move to opposite poles
What comes after the Interphase?
The prophase of Mitosis
What happens during the Prophase? (4)
1. Chromosomes condense (chromatids are connected at the centromeres) 2. Kinetochores form near centromeres 3. Mitotic Spindle assembly 4. Nucleolus Disassembles
What happens during the Prometaphase? (2)
- Breakdown of nuclear envelope (lamin proteins)
2. Mitotic Spindle binds to Kinetochore
What happens during the Metaphase? (2)
- Chromosomes bind to Kinetochore
2. Line up along metaphase plate (via Motor proteins)
What happens during the Anaphase? (1)
- Sister Chromatids Separate
What happens during the Telophase? (3)
- Sister chromatids de-condense at opposite poles
- Nuclear envelope re-assembly
- Contractile ring assembly
What happens during Cytokinesis? (1)
- Actin/Myosin contraction pinches contractile ring to DIVIDE CYTOPLASM
How is the cell cycle regulated?
- Cyclin-CDK Complexes
- Cyclin-CDK Complex Inhibitors
* CDK = Cyclin-dependent Kinase*
List the regulators of the G1, S, G2, and M checkpoints respectively:
- —->G1 Checkpoint:
- Cyclin D
- CDK 4/6
- Rb Proteins
- p53
- —–>S Checkpoint:
- Cyclin E and A
- CDK 2
- —–>G2 Checkpoint:
- Cyclin A
- CDK 1
- —–>M Checkpoint
- Cyclin B
- CDK 1
- APC (Anaphase Promoting Complex)
Define Rb Protein: When are they active?
Tumor suppresor proteins that are active when HYPO-PHOSPHORYLATED.
What causes Rb proteins to become inactive? What is the result of this inactivation?
- Increased Cyclin D/CDK-4/6 activity causes their hyper-phosphorylation
- Unregulated proliferation leading to cancer and gene mutation
How is the CyclinB/CDK1 complex formed that is required to initiate Mitosis at the G2-checkpoint?
- Cdc-25 Phosphatase: (a proto-oncogene) Removes an inhibitory phosphate from CDK-1
* Note: Cdc not Cdk*
Are CDK’s active when phosphorylated or de-phosphorylated?
Active = De-phosphorylated
When does Cdc-25 become activated (to then, in turn, activate CDK-1)?
Not until DNA replication is completed
What is p53? Give its 2 roles: _______.
- It is a TRANSCRIPTION FACTOR that is a tumor suppressor.
- Two Roles:
a. ) Reg. of cell cycle by stimulating transcription of CDK-inhibitory proteins
b. ) Initiation of Apoptosis if needed
What 2 things does the Anaphase Promoting complex do?
- Separation of Sister Chromatids
2. Degradation of Cyclin B from M phase
How does the APC separate sister chromatids? (3)
- Tags SECURIN with ubuquitin, so it’s degraded by the proteasome.
- REMOVAL of this securin activates SEPARASE
- Separase cleaves the Cohesin Complexes
Besides p53, what other tumor suppressor acts at the G1 checkpoint and how does it function?
p21 = Inhibits CDK’s
If DNA is not prepared for the S phase, what acts to compensate for this?
BRCA1 = Repairs double stranded breaks in DNA
What is the function of ATM/ATR?
Inactivation of Cdc25 at the G2 checkpoint if DNA is damaged. This prevents activation of CDK-1 needed for M phase.
Differentiate between Proto-oncogenes and Oncogenes:
- Proto-Oncogenes: Genes whose products control normal proliferation/differentiation
- Oncogenes: Mutated Proto-Oncogenes
Telomerase Function:
Elongates telomeres so that cells can keep dividing longer
What happens if telomerase is over-expressed?
Cells will proliferate abnormally
i.e. Cancer progression
Define Meiosis:
Reproductive cell division
Describe Meiosis ONE: (2)
- Separation of homologous chromosomes
- DNA content reduced from 4d to 2d
i. e. Chromosomes from 2n to 1n
Describe Meiosis TWO: (2)
- Separation of sister chromatids
- DNA content reduced from 2d to 1d
i. e. Chromatids from 2 to 1 each
How many chromosome does each daughter cell receive from meiosis?
1 haploid set = 23 chromosomes
Describe the 5 steps of Prophase 1 in Meiosis:
- Leptotene: Sister chromatids condense and connect, parental chromosomes BEGIN to pair.
- Zygotene: Parental chromosomes come in close contact, formation of Synaptonemal Complex that WILL soon bind them together.
- Pachytene: Completion of synaptonemal complex, CROSSOVER- i.e. double helices break, ends join opposite partners, helices re-form, and recombinant chromatids are created.
- Diplotene: Synaptonemal complex breaks down, parental chromosomes being separation. Chiasmata, junctions between chromosomes, are formed.
- Diakinesis: Parental chromosomes condense, nucleolus and nuclear envelope disappear.
What is an indicator that cross-over may have occurred in reproductive cell meiosis?
Presence of Chiasmata (the junctions between parental chromosomes)
What happens in Metaphase 1 of Meiosis? (2)
- Parental chromosomes line up on plate
(still connected via chiasmata) - Meiotic Spindle attaches to kinetochores of the sister chromatids
What happens in Anaphase 1 of Meiosis? (1)
- Parental chromosomes pulled to opposite poles
What happens in Meiosis 2?
Essentially same as Mitosis. No DNA replication, no cross-over, just separation of sister chromatids.
How is Aneuploidy caused in Meiosis Or Mitosis?
Nondisjunction: Chromosomes fail to separate during Anaphase. Leads To: -Trisomy (gain of 1 chromosome) -Monosomy (loss of 1 chromosome) -Nullisomy (loss of both chromosomes)
How is Polyploidy different from Aneuploidy?
Polyploidy is a gain of one or more WHOLE SETS of chromosomes.
i.e. Triploid, tetraploid, etc.
Describe the 4 types of chromosome damage/fragmentation:
- Deletion: Fragment Lost
- Translocation: Fragment attaches to another chromosome
- Inversion: Fragment re-attaches to same chromosome. but orientation is reversed
- Duplication: Fragment is treated as a separate chromosome and produces double genes
What is unique about Ca2+ dependent K Channels?
They are sensitive to both:
- Ca2+ conc.
- Voltage
Which gate of the Voltage-gated Na+ channel is the quickest acting? How do each of the gates respond to depolarization?
- The M gate, aka the Activation Gate.
- Depolarization Leads To:
- ->M Gate: OPEN FAST
- ->H Gate: CLOSE SLOWLY
Describe the Repolarization phase of the Voltage-Gated Na+ channel:
The ABSOLUTE REFRACTORY period, in which the channel cannot be activated again because the M gate is still open, but the H gated has closed.
What two things are delayed rectifier channels dependent on? What triggers them?
- Voltage
- Time
- Triggered By: Depolarization, but opening is delayed.
What determines the likelihood of action potential firing and how?
Rate of depolarization: Long and slow = REDUCED excitability due to:
- Locking of Na+ channels closed
- Increased K+ delayed rectifiers open
Compare the effects of Hypo- and Hyperkalemia on action potentials:
- Hypokalemia: Too HYPERPOLARIZED cells, too far from threshold to fire as fast.
- Hyperkalemia: The Ek ITSELF is reduced/depolarized, so H-gates stay closed and Vm stabilizes near the new Ek.
* Can lead to weakness/paralysis*
How do Hypo- and Hypercalcemia affect the rate of action potential firing?
- Hypocalcemia: Threshold is hyperpolarized, leads to INCREASED firing rate.
* Can lead to Tetany in muscle tone* - Hypercalcemia: Threshold is depolarized, leads to DECREASED firing rate.
* Can lead to Weakness*
6 Characteristics of Epithelial Cells:
- Avascular (relies on vasc. of conn. tissue)
- Sits on a Basement Membrane
- Continuous
- Little/No Space Between Them
- Joined by Junctional Complexes
- Lines cavities, surfaces, lumens, etc.
3 Components of Nucleotides:
- Base
- Pentose Sugar (Ribose/Deoxyribose)
- Phosphate Ester @ C-5
Identify Purines and Pyrimidines:
Purines: A and G
Pyrimidines: T and C
Differentiate between Ribose and Deoxyribose:
Ribose has a C-2 -OH group
Deoxyribose has a C-2 “H” molecule
Difference between a nucleoSIDE and a nucleoTIDE:
- ->Nucleoside:
- Base and Sugar (ONLY)
- ->Nucleotide:
- Base
- Sugar
- Phosphate
What is the energy source for the formation of Phosphodiester Bonds by DNA/RNA Polymerase?
Cleavage of Pyrophosphate (PPi) from the new dNTP being added to the chain
What is the energy source for the formation of Phosphodiester Bonds by DNA Ligase?
- Ligase uses dNMP’s
2. Energy Source = ATP
How are the 2 strands of DNA in the double helix held together?
By H-bonds between complimentary base pairs
Differentiate between A-T and G-C bonding:
What does this tell us about the DNA structure as a whole?
- A-T: Forms only 2 H-bonds (WEAKER)
G-C: Forms 3 H-bonds (STRONGER) - HIGHER amounts of G-C bonding give the DNA a higher MELTING POINT
Define Melting Point:
The point at which 50% of the H-bonds between base pairs are broken
Where do proteins interact with DNA during transcription?
The Major and Minor Groove
Describe Primary to Quaternary structure of DNA/RNA:
1’ : Nucleotide Sequence
2’: Double Helix (3D structure)
3’: Supercoiling of Helix (of 2’ structure)
4’: Interaction with histones/proteins
Function of Small Nuclear RNA (snRNA):
Involved in SPLICING to remove introns
i.e. DNA maturation
Function of MicroRNA (miRNA):
How do they accomplish this function?
- SILENCING of gene expression
- a.) They combine with RNA-induced Silencing Complex and deliver it to specific mRNA.
b. ) That downregulates the mRNA’s translation by:
- Blocking the Ribosome
- Degrading the mRNA itself
What is an example of Facilitated Diffusion?
Fructose crossing intestinal epithelial cells
Differentiate between the two types of Glucose transporters:
- GLUT-2 = Basolateral Membrane
i. e. Movement into/out of BLOOD - SGLT-2 = Apical Membrane
i. e. Movement into/out of Lumens (Abs./Sec.)
What activates CFTR’s:
cAMP
How does knocking out the Na/K-ATPase affect the Vm of the cell?
The Na/K-ATPase sets up the K+ gradient OUT of the cell, so without it the cell will REpolarize until the Vm = 0.
i.e. INCREASED (+) charge Outside the cell
Differentiate between the effects of Hypo- and Hyperkalemia on action potentials:
- HYPOkalemia: Hyperpolarized membrane
i. e. Too far from threshold - HYPERkalemia: Longer refractory period
i. e. Won’t fire again
How could one differentiate between necrosis and apoptosis of a cell by observing the DNA?
- Necrosis: DNA will be smeared, random cleavages
2. Apoptosis: DNA will be sharp and defined
Why wouldn’t Cholesteryl Esters be found in the bilayer?
They are HIGHLY polar structures
How can you determine if RNA/DNA is single stranded or double stranded by observing the content of each base?
If it is double stranded, the G% = C%. Otherwise it must be single stranded DNA/RNA.
What can you assume if DNA fragments are observed to be normally sized in a sample?
DNA Ligase is functioning properly
What 2 structures do PROKARYOTES use for supercoiling their DNA?
- Topoisomerases (Supercoiling)
2. HU Proteins (LOCK in supercoiled form)
How is prokaryotic DNA termed when it is bound by Topoisomerase 1, Gyrase, and HU proteins?
Called a Nucleoid
i.e. Loops of supercoiled DNA around a protein core
Although both (+) and (-) supercoiling condense the DNA, what is the primary functional difference between the two?
- (+) supercoiling: Makes it DIFFICULT to separate DNA during replication–>Must be fixed by Topoisomerase 2 or Gyrase
- (-) supercoiling: Makes it EASIER to separate DNA
What does Ciprofloxacin do?
- Inhibits DNA Gyrase
2. (+) Supercoils build up and prevent DNA replication because the DNA can’t be unwound
Differentiate between the function of Topoisomerases 1 and 2:
- Topoisomerase 1: Breaks 1 strands backbone and temporarily “holds it’s backbone” while it unwinds aroun. This “holding” is a transient COVALENT bond.
- Topoisomerase 2: Breaks BOTH backbones
What are 2 unique features of Topoisomerase 2/Gyrase that are not true of Topoisomerase 1?
- REQUIRES ATP
2. Also has de-tangling function
Why is DNA attracted to histones (wants to wrap around them)?
Their Amino Acids give them a (+) charge and DNA has a (-) charge
What are the 1st and 2nd levels of DNA packaging?
1st: Nucleosome (10nm Fiber)
2nd: Multi-nucleosome (30nm Fiber)
* requires H1 proteins*
How does Histone Acetylation affect DNA packaging?
It FAVORS euchromatin formation
i.e. PREVENTS DNA from wrapping tightly
5 Requirements for DNA Replication:
- All 4 bases (a,c,t,g,)
- A template fragment
- DNA Polymerase
- Mg2+ ions (COFACTORS for DNA Polymerase)
- A Primer providing a 3’-OH
How does Azidothymidine (AZT) work?
Anti-HIV drug that prevents phosphodiester bond formation (and therefore DNA replication) by adding an Azido group where the 3’-OH needs to go.
What is required for AZT to work? How does it target HIV cells and not our own?
- It is a nucleoSIDE (no PO4-), so it must be phosphorylated 3 times.
- It has a high affinity for viral DNA
What specifically in viral DNA does AZT have a high affinity for?
Reverse Transcriptase is favored over the human analogue (DNA Polymerase).
Name another drug that has a mechanism similar to AZT:
Didanosine
What nucleoside analogue treats herpes and how is it different from AZT and Didanoside?
Acyclovir: Relies on the Herpes Kinase to add the 1st phosphate, so ONLY herpes cells can activate it.
What is the 4th nucleoside analogue discussed (besides AZT, Didanoside, and Acyclovir) and how does it work? Also what does it treat?
- Cytosine Arabinoside (araC): Has a 3’-OH, but ALSO has a 2’-OH which repels it and makes it unable to form phosphodiester bonds.
- Treats Leukemia
What is the only NucleoTIDE analogue discussed and how does it work? Also what does it treat?
- Tenofovir: Has one phosphate already (nucleoTIDE), so it only needs 2 more to be active.
- Treats HIV
List the 5 analogues (nucleoside/nucleotide) and what they treat:
- AZT: HIV
- Didanoside: HIV
- Acyclovir: Herpes
- Cytosine Arabinoside (araC): Leukemia
- Tenofovir: HIV
How are mis-paired bases corrected in DNA replication?
By the Proof-reading Exonuclease activity of the same DNA Polymerase that joins them together.
Theta Replication:
DNA Replication of Prokaryotes whose DNA has only ONE origin of replication (OriC).
Describe the “rolling circle” model of theta replication:
The leading Strand is replicated circularly while the lagging strand is “peeled off” of the circle.
Linear Replication:
Eukaryotic DNA replication involving many origins of replication
Differentiate between the Leading and Lagging Strands:
- –>Leading:
- Continuous replication
- TOWARD replication fork
- –>Lagging:
- Discontinuous replication
- AWAY FROM replication fork
7 Structures Involved in Prokaryote DNA Replication and their functions:
- DnaA: Binds OriC and breaks H-bonds btwn bases
- DnaB: Helicase at rep. forks
- DnaC: (Helicase Inhibitor) Delivers helicase to forks
- DNA Primase: An RNA polymerase that makes an RNA Primer on the lagging strand
- DNA Pol. 1: Removes RNA primer, replace with DNA
- DNA Pol. 3: Synthesis of both strands
- ssBP’s: Bind at rep. fork and prevent it’s re-annealing
Describe the 3 activities of DNA Polymerase 1 and their directionality:
- Removal of RNA Primer: 5’-3’
- Replacement with DNA: 5’-3’
- Proof-reading base pairs: 3’-5’
Describe the base content of the OriC:
Very A-T rich, therefore easily separated for replication
Where do DnaA proteins bind and where does strand separation begin?
- DnaA binds at 9-nucleotide sequences
2. Separation begins at the 13-mer sequences
Primosome:
Helicase + DNA Primase
DNA Ligase:
Uses ATP to form phosphodiester bonds that join Okazaki fragments
What do Eukaryotes use instead of DNA Polymerase 1?
RnaseH and FEN-1 Protein: Remove RNA primer and replace with DNA
Function of the Clamp Protein:
Holds DNA Polymerase 3 in place so long strands can be synthesized
What is the function of telomerase and how is it accomplished?
Telomerase: Fills in the gaps at the 5’ ends of DNA that DNA polymerase couldn’t fill because it only adds bases from 5’-3’. Telomerase has REVERSE TRANSCRIPTASE activity, so it can use an RNA template to fill the gaps.
2 Eukaryotic DNA Polymerases:
- DNA Polymerase Alpha: Synthesizes RNA primer (essentially a DNA Primase)
- DNA Polymerase Delta: Synthesizes DNA (main replicative enzyme) and has 3’-5’ proof-reading exonuclease activity
Describe the 3 drugs discussed that inhibit EUKARYOTIC DNA replication:
- Camptothecin: (Anticancer) Inhibits Topoisomerase 1, causing DNA breakage
- Etoposide: (Anticancer) Inhibits Topoisomerase 2
- Actinomycin D: (Anticancer) Intercalates between G-C pairs and prevents unwinding of DNA
i. e. No REPLICATION or TRANSCRIPTION
Protamines:
(+) Charged molecules that package DNA in sperm because Histones are too large to do so
4 Basic Types of Tissue:
- Epithelial
- Connective
- Nerve
- Muscle
3 Characteristics of Epithelial Cells:
- Form specialized junctions
- Exhibit polarity:
- Apical, Basal, and Lateral Membranes - Basal Surface attached to basement membrane
5 Main Functions of Epithelial Cells:
- Absorption
- Secretion
- Transportation: Cilia (motile)
- Protection: (Skin) Strat. Squam.
- Receptor: Receive/Transduce EXTERNAL Stimuli
How are stratified epithelial cells identified?
Based on the OUTERMOST layer appearance/structure
3 Locations of Simple Squamous Epithelium:
Overall Function =
- Bowman’s Capsule
- Alveoli
- Blood vessels/Lymph Vessels (endothelium)
Overall Function = Exchange/Lubrication
5 Locations of Simple Cuboidal Epithelium:
Overall Function =
"TOP-LP" 1. Thyroid Follicle 2. Ovary 3. Pancreatic Duct 4. Liver Hepatocyte 5. Prox./Dist. Tubule Overall Function = Absorption/Secretion
5 Locations of Simple Columnar Epithelium:
Overall Function =
"SLUGS" 1. Small Intestine (Abs./Goblet Cells) 2. Large Intestine (Abs./Goblet Cells) 3. Uterine Tube 4. Galbladder 5. Stomach (Gastric Pits) Overall Function = Absorption/Secretion
2 Locations of Pseudo-stratified Epithelium:
Overall Function =
“Male Reproductive Tract–> Throat”
1. Trachea /bronchial tree (Goblet/Cilia/Basal Bodies)
2. Male reproductive tract (Ductus Epididymis/Ductus Deferens)
Overall Function = Conduit (Abs./Sec.)
3 Locations of Stratified Squamous Epithelium:
Overall Function =
"Needs to be tough/thick for a reason" 1. Vagina 2. Esophagus 3. Skin Overall Function = Barrier/Protection
ONLY Location of Stratified Cuboidal Epithelium:
Overall Function =
- Sweat Gland DUCTS
Overall Function = Conduit
2 Locations of Stratified Columnar Epithelium:
Overall Function =
- Largest Ducts
- Anorectal Junction
Overall Function = Conduit
What is the main difference between function of Stratified Cuboidal and Stratified Columnar Epithelium?
Stratified Columnar serve the same function(act as a conduit for transport) but for LARGER ducts
ONLY location of Transitional epithelium:
Overall Function =
- Urinary System
i.e. “RUBU”
—Renal Calyces
—Ureter
—Bladder
—Urethra
Overall Function = Distension
3 Types of Apical Specializations:
- Cilia
- Stereo-cilia
- Microvilli
3 Types of Lateral Specializations:
- Adhering Junctions
- Occluding Junctions
- Communicating Junctions
ONLY type of basal specialization:
Anchoring junctional complexes
Function of stereo-cilia:
Increase S.A.
Differentiate between the Paracellular and Trans-cellular pathways:
- Paracellular: Movement between cells from apical to basal that only passes through the tight junction itself (i.e. alongside the cells)
- Trans-cellular Pathway: Movement THROUGH the cell itself, avoiding the tight junction from apical to basal
Give the Transmembrane Proteins that make up each of the Lateral Junctions of Epithelial Cells:
- Zonula Occludens–> Clauden and Occludin
- Zonula Adherens–> E-Cadherin
- Macula Adherens–> Desmocolli and Desmoglein
(and Plakoglobins/Desmoplakins BTWN cells) - Gap Junctions–> Connexons/Connexins
What is another name for a Desmosome?
Macula Adherens Junction
What are Plicae?
Where are they found?
- LATERAL folds of processes that increase surface area of the lateral aspect of the cell
- Found in cells specialized for fluid transport
Differentiate between the 2 types of Basal Specializations:
- Focal Adhesions: (Cell to Extracellular Matrix) Made up of ACTIN filaments.
- Hemi-desmosomes: (Cell to Extracellular Matrix) Made up of INTERMEDIATE filaments.
What results from a desmosome or a hemi-desmosome breaking respectively?
- Desmosome: Cells break off from other cells
i. e. INTRA-epidermal blister - Hemi-desmosome: Cells break off from basement membrane
i. e. SUB-epidermal blister
Why would BASAL plicae be found in different cells than lateral plicae?
Basal infoldings increase basal surface area so that more TRANSPORT protens and CHANNELS can be inserted. Therefore they are present in cells performing lots of ACTIVE TRANSPORT.
i.e. Kidney tubule/Striated Ducts
What type of microscopy appreciates visualization of the basement membrane?
LIGHT microscopy
What 2 substances compose the basement membrane?
- Glycoproteins
2. Proteoglycans
Describe the Basal Lamina:
1. It is the OUTER layer OF the basement membrane (also called the external lamina) 2. It has 2 layers itself: -->Lamina Lucida -->Lamina Densa
Differentiate between the 2 major types of Glands:
- Exocrine: Secrete onto a surface directly OR through ducts connected right to the surface.
- Endocrine: Secrete hormones into connective tissue that then go into the bloodstream.
3 Major Exocrine Gland types and their mechanism of secretion:
- Merocrine: Exocytosis of membrane-bound vesicle
- Apocrine: BLEB of plasma membrane forms vesicle
- Holocrine: NO VESICLE. Entire cell lyses and IS the secretion.
Give exmaples of Apocrine and Holocrine glands respectively:
- Apocrine: Mammary Glands for lactation
2. Holocrine: Sebaceous Glands lyse onto hair follicles
Describe the 2 types of endocrine signaling that don’t act on distant targets:
- Paracrine: Secreting to nearby cells
2. Autocrine: Releasing into same cell
Give an example of a unicellular gland:
What do they secrete?
- Goblet Cells
2. Mucous
Describe the 2 ways of classifying multicellular glands based on structure:
- By Shape of Secretory Cells:
- -a.) Tubular: Tube
- -b.) Acinar: Flask
- -c.)TubuloAcinar: Tube ends in a dilation - By Branching of Glands:
- -a.) Unbranched: Simple
- -b.) Branched: Compound
Describe the 3 gland classifications based on type of secretion:
- —->1. Serous:
- Watery Secretion
- Round/Oval Nuclei
- Granular Apex (stain with Eosin)
- —->2. Mucous:
- Slimy
- Flattened Nuclei at Base
- Store Oligosaccharides in mucous (stain with PAS)
- Appear Empty with H&E stain*
- —->3. Mixed:
- Mucous and Serous Components
- Compound Tubuloacinar Glands
- Ex: Submandibular gland
