Exam 1 Flashcards
What are the two components of phospholipids?
Hydrophilic head (charged and polar) Hydrophobic tail (nonpolar) that is made up of fatty acids and impermeable to water soluble molecules.
Describe the function of phospholipids.
Barrier with selective permeability. Makes up the phospholipid bilayer.
What are the three components of the nucleus?
Chromatin, nuclear envelope and the nucleolus.
What are the two kinds of chromatin and how do they structurally differ?
Euchromatin and heterochromatin. Euchromatin is a less coiled chromatin and heterochromatin is condensed.
What is the functional difference between euchromatin and heterochromatin?
Euchromatin is transcriptionally active, whereas heterochromatin is transcriptionally inactive.
Describe the components of the nuclear envelope and the structure of each.
There is an outer and inner membrane. The outer membrane is continuous with the membrane from the ER and thus, has ribosomes attached. The inner membrane is associated with lamin (intermediate filaments) which stabilize the envelope.
What stabilizes the nuclear envelope?
Lamins (intermediate filaments)
What chromatin is associated with RNA synthesis?
Euchromatin
Describe the function of the nucleolus.
It is the site of rRNA synthesis and assembles ribosomal subunits.
Describe how ribosomal subunits are imported to the nucleolus.
The ribosomal subunits are imported from the cytoplasm through the nuclear pore complex.
What is the function of the nuclear pore complex.
To create bidirectional communication between the inner and outer membranes of the nuclear envelope.
Describe how the nucleolus looks under an EM.
Nucleolus is very dark (basophilic) due to its concentrated rRNA.
When would the nucleolus be visible while looking under an EM.
When cells are active in protein synthesis.
Why is the nucleolus very dark when stained.
Is the nucleolus basophilic or acidophilic, and why?
It is basophilic because there are acidic components in the cell. The nucleolus is dense with concentrated ribonucleic acid that are active in protein synthesis, and have affinity towards basic stains (basophilic).
What are the phases in mitosis?
Prophase, Metaphase, Anaphase and Telephase.
Describe prophase.
Chromosomes condense and become visible.
Nuclear envelope disappears.
Describe metaphase.
Mitotic spindle becomes organized around the centrioles and chromosomes align along the equatorial/metaphase plate.
In what phase do chromosomes align to the equatorial plate?
Metaphase.
In what phase do centromeres split?
Anaphase
In what phase is cytokinesis visible?
Telephase
Describe anaphase.
Centromeres split and chromatids are separated due to the pull of kinetochore microtubules.
The pull comes from the mitotic spindle (microtubules) shortening.
Where is glycogen most abundant?
Skeletal muscle and liver cells
Where are lipids most abundant?
Adipocytes, adrenal cortex and liver cells
Where is melanin (pigment) most abundant?
The skin, hair and pigmented layer of the retina.
What is the cytoskeleton?
The network of proteins in the cytoplasm.
What are the functions of the cytoskeleton?
Support, strengthen, move, phagocytosis, cytokinesis.
What are the three different size groups of the cytoskeleton?
Microfilaments, intermediate filaments and microtubules.
Describe necrosis and how the cell dies.
Pathological in response to injury. The cell ruptures due to injury and releases digested and broken enzymes which triggers inflammations.
Describe apoptosis and how the cell dies.
Deliberate - not accidental, genetically programmed cell suicide.
Describe what pyknosis looks like under a light microscope.
Chromatin condensing
Describe what cytoplasmic budding looks like under a light microscope.
Membrane bound fragments begin to appear.
Describe what apoptotic bodies looks like under a light microscope.
Cell fragments that contain nuclear material.
How do the inflammatory response differ in necrosis versus apoptosis?
In necrosis, the cell pops and a very quick inflammatory response occurs. In apoptosis, the cell slower self-destructs and does not trigger an inflammatory response.
Describe the steps of the cell cycle.
G1
S
G2
Mitosis
Describe the First Growth Phase in the cell cycle.
Longest step; RNA synthesis and synthesis of proteins occur. Cell increases volume.
Describe the Synthesis phase of the cell cycle.
DNA synthesis and duplication occurs.
Describe the Second Growth Phase of the Cell Cycle.
More growth; proteins needed for mitosis synthesized; DNA checked for errors.
What controls the progression of the steps throughout the cell cycle?
Cyclins and protein kinases.
What is tissue?
Aggregation of cells that function together.
What are the four main types of tissue?
Epithelium and Glands
Connective Tissue
Muscle Tissue
Nervous Tissue
Describe the structure of cholesterol in the plasma membrane.
Cholesterol wedges itself between the phospholipid tails of the membrane.
Describe the function of cholesterol in the plasma membrane.
Cholesterol works to modulate fluidity. At high temperatures, the membrane has more fluidity and the cholesterol keeps the membrane rigid during those high temperatures by restricting movement of phospholipids.
Describe the structure of glycolipids.
Outer leaflet attached to the bilayer. It is a lipid with a carbohydrate covalently attached.
Describe the function of glycolipids.
Cellular recognition.
Describe the two kinds of membrane proteins.
Peripheral proteins which are linked to the membrane indirectly by protein-protein interactions.
Integral proteins which are inserted directly into the bilayer.
Describe the function of membrane proteins.
Aid with diffusion of molecules across bilayer (glucose, charged molecules and small ions),
Describe the difference between carrier transporter proteins and channel transporter proteins.
Carrier transport proteins bind to molecules that need to be transported.
Channel transport proteins form and open gates; rapid ion transport.
What is the primary function of the Rough ER?
Protein synthesis.
What is the primary function of the Smooth ER?
Detoxification (converts lipid-soluble and water insoluble materials into water-soluble compounds that can be excreted).
Involved with synthesis of steroids, cholesterols and triglycerides.
What is the primary function of ribosomes?
Protein synthesis
What is the difference between smooth and rough ER?
Smooth ER lacks ribosomes.
What is the primary function of the golgi apparatus?
Sort proteins, glycosylation, synthesis of sphingomyelin and glycosphingolipids, sorts “cargo”
What is the primary function of lysosomes?
Break down materials (“inner cell trash”)
What is the functional difference between primary and secondary lysosomes?
Primary is inactive and acts as storage for lysosomal hydrolases.
Secondary is active and involves phagolysosomes and autolysosomes.
At what pH does the degradation process occur?
pH of about 5
What is the primary function of endosomes?
Ingestion and sequestering. Helps to prepare for degradation by fusing with lysosomes
What is the primary function of proteasomes?
Degrades old or damaged proteins that have been tagged with ubiquitin.
What is the primary function of the mitochondria?
ATP synthase, steroidogenesis, thermogenesis (ATP -> brown fat), apoptosis
What is the primary function of peroxisomes?
Contains oxidase which produces hydrogen peroxides. Contains catalase which breaks down hydrogen peroxide. Synthesizes bile acids, cholesterol and lipids
Where are peroxisomes found and not found?
Peroxisomes are found in all mammalian cells EXCEPT erythrocytes.
Describe the main Component of microfilaments.
Actin
Describe the function of microfilaments.
Cytoplasmic extensions, contraction of myosin in skeletal muscle, division of mitotic cells
Endo/exo-cytosis
Where are microfilaments found?
Microvilli -in the intestinal and renal epithelial cells
Stereocilia in hair and inner ear
Myosin in skeletal muscle
What are the 5 major types of intermediate filaments?
I and II Keratin III Vimentin III Desmin IV Neurofilaments V Lamins
Describe the structure of intermediate filaments
Rod-like proteins; they have 2 antiparallel dimers which form a tetramer. They form 8 tetramers which then form a unit length filament.
Describe the function of intermediate filaments
Provide strength and resistance to stretching, compression, twisting and bending; scaffolding of other structures.
Describe where keratin can be found.
Epithelial cells
Describe where vimentin can be found.
Fibroblast, chondroblast, macrophages, endothelial cells and vascular smooth muscles
Describe where desmin can be found.
Skeletal and smooth muscle; z-discs
Describe where neurofilaments can be found.
Dendrites and axons of neurons
Describe where lamins can be found.
Nuclei of most cells; associated with the inner membrane of the nuclear envelope - provides strength and stability to the nucleus. Also binds to the chromatin.
Describe the function of lamins.
Mechanical support, binds chromatin
Describe the function of keratin.
strength and protection against abrasion and water loss
List the elements of the cytoskeleton from smallest to largest.
Microfilaments, intermediate filaments and microtubules.
Describe the function of microtubules.
Maintains cell shape, intracellular transport, provides a basis for centriole basal bodies, cilia and flagella.
Describe the structure of centrioles.
Cylindrical structure composed of 9 microtubule triplets
Describe the structure of cilia and flagella.
Cylindrical structure composed of 9 microtubule doublets that surround 2 central microtubules.
Describe the structure of basal bodies.
9 microtubule triples that make the origin of cilia and flagella.
What is bulk flow?
All of the solvents and solutes moving because of a driving force or pressure.
What is diffusion?
Solutes can travel in either direction but net diffusion will occur when a solute travels from an area of HIGH to LOW concentration using the inherent energy of molecules that drive the transport.
What is osmosis?
Net diffusion of solvent water from high to low concentration
What is mediated transfer?
Large or polar molecules that cannot diffuse through the membrane must be carried through by a protein molecule : distinguishable from diffusion because the kinetics are different.
Describe the proportionality of rate and distance.
1/distance^2
Describe if bulk flow would be better than diffusion when regarding distance.
Bulk flow is better over longer distance than diffusion because diffusion is only useful across a distance of about the diameter of a few cells.
Describe facilitated diffusion.
Gradient is present, and the solute travels from high to low diffusion. Kinetics are similar to mediated transport.
Describe simple diffusion.
No carriers, material can just cross the membrane down the concentration gradient as necessary
Describe carrier-mediated transport.
Selective, helps bring in ions and small molecules but keeps the two sides of the membrane separated.
Describe receptor-mediated endocytosis.
Membrane receptors bind specific ligands only and eventually are pinched off into a vesicle on the inside by proteins.
For molecules that are too big or oddly shaped.
NOTE: Gout
What is the dilution principle?
V = Q/C
Describe isotonic influx.
ECF is larger volume, but cell bodies are unchanged. Kidneys excrete salt and water to bring volume back to normal.
Ex. Drinking a lot of water
Describe isotonic efflux.
ECF volume decreases but cell bodies are unchanged. Kidneys conserve salt and water.
Ex. hemorrhage, burns, diarrhea, etc.
Describe hypotonic influx.
ECF volume increases, ECF osmolarity decreases by dilution. ICF swells. Kidneys excrete dilute urine.
Describe hypotonic efflux.
ECF volume is lost, ECF osmolarity rises because more water is lost than salts. Kidney conserves water and excretes salt.
Ex. Exercise
Describe hypertonic influx.
ECF volume increases, ECF osmolarity increases.
Cell bodies are dehydrated and kidneys excrete concentrated urine.
Describe hypertonic efflux.
Rare
Ex. Hormonal imbalance
Describe distribution of water amongst body fluid compartments.
ICF - 40% of body weight
ECF - 20% of body weight (interstitial fluid - 16% and plasma is 4%)
Name types of connective tissue.
Embryonic (Mesenchyme and Mucous) and Adult (Connective tissue proper and
Specialized)
What are the osmotic concentrations in a healthy person?
-290mOsm
Where is connective tissue derived?
Mesoderm
List specialized connective tissues.
Adipose, cartilage, bone, blood
Describe the different kinds of muscle and the location of each.
Skeletal muscle - attached to skeleton
Cardiac muscle - heart and major blood vessels coming into and out of the heart
Smooth muscle - all other blood vessels and hollow organs
Describe the apical domains of epithelia.
Top layer, exposed to air, fluid and ingested substances (glycocalyx, microvilli, stereocilia, or cilia); may attach to epithelium if stratified
Describe the lateral domains of epithelia.
Specialized junctions that facilitate adhesion
Describe the basal domains of epithelia.
Can be attached to basement membrane or to epithelium if stratified
Describe the different layering types of epithelia.
Simple, which is one layer thick and stratified which is two layers thick
Describe the different shape types of epithelia.
Squamous, cuboidal, and columnar
Describe the different types and function of epithelia.
Intestinal - absorption Glandular - secretion Skin - protection Respiratory - transport Lung alveoli - gas exchange Kidney - excretion Neuroepithelium - sensory reception
Describe where in the body, simple squamous epithelium is found.
Lining the body cavities and organs (mesothelium)
Lining blood and lymphatic vessels (endothelium)
Loop of Henle
Alveoli in lung
Bowman’s capsule in renal corpuscles
Describe where in the body, simple cuboidal epithelium is found.
Small ducts of exocrine glands, thyroid glands, germinal epithelium of the ovary, kidney tubules
Describe where in the body, simple columnar epithelium is found.
Stomach, small intestine, large intestine, gallbladder, uterus
Describe the two types of stratified squamous epithelium.
Keratinized (skin, palms of hand) - dead cells at surface - and nonkeratinized (esophagus, vagina,etc) - surface cells still have living nuclei.
Describe where in the body, stratified cuboidal epithelium is found.
Sweat glands, larger ducts of exocrine glands
Describe where in the body, stratified columnar epithelium is found.
Largest ducts of exocrine, portion of male urethra
Describe where in the body, pseudostratified epithelium is found.
Trachea, bronchi of respiratory system, efferent ductules, epididymis and vas deferens
Describe where in the body, transitional epithelium is found.
Urinary system only! Can distend (squamous) and contract (cuboidal) in shape (bladder, etc.)
Describe types of specialized epithelia and where in the body it is found.
Neuroepithelium (olfactory), pigmented (retina), Germinal (seminiferous tubules of testes), Myoepithelium (contractile cells of glands that push secretion out)
Describe the function of simple squamous epithelium.
Allows materials to pass through by diffusion and filtrtion and secretes lubricating substance
Describe the function of simple cuboidal epithelium.
Secretes and absorbes
Describe the function of simple columnar epithelium.
Absorbs; secretes mucous and enzymes
Describe the function of pseudostratified columnar epithelium.
Secretes mucus; ciliated tissue moves mucus
Describe the function of stratified squamous epithelium.
Protects against abrasion
Describe the function of stratified cuboidal epithelium.
Protective tissue
Describe the function of stratified columnar epithelium.
Secretes and protects
Describe the function of transitional epithelium.
Allows urinary organs to expand and stretch
What is glycocalyx?
Fuzzy coating of carb residue attached to transmembrane proteins, protects surface cell
What are the two components of the basement membrane?
Basal lamina and Reticular lamina
What are the two components of the basal lamina?
Lamina lucida (lucent layer) and lamina densa (dense layer)
What type of collagen is in the basal lamina?
Type 4
What type of collagen is in the reticular lamina?
Type 3
What type of epithelia are in the exocrine glands?
Simple alveolar
Simple tubular
Simple coiled tubular
Simple branched tubular
Describe the difference between secretion in the exocrine and endocrine glands.
Exocrine secretes to the surface of the epithelia. Endocrine secretes into connective tissue to enter the blood stream to further reach target
Describe merocrine secretion.
Secretory product formed and enclosed by membrane which fuses to the cell membrane during discharge - salivary and pancreatic glands
Describe apocrine secretion.
Secretory product accumulates in the apical portion of the cell and is pinched off
-lactating mammary gland
Describe holocrine secretion.
Entire secretory cell is discharged - sebaceous gland
Describe intralobular secretion.
Ducts are located within a lobule
Describe interlobular secretion.
Ducts are between lobules
Describe the difference between unicellular and multicellular.
Unicellular is single cells (goblet cells)
Multicellular have acinar/alveolar shaped secretory units
Describe mucous cells.
Has mucins, hydrophilic glycoproteins that are slimy
Describe serous secretion.
Watery with lots of proteins and enzymes, abundant in RER, stained with hematoxylin and eosin
Describe mixed secretion.
Contains both mucous and serous secretory units
What surrounds the parenchyma and why?
Stroma, the connective tissue, surrounds the parenchyma, provides support
What forms the parenchyma?
Secretory units and ducts form the parenchyma
What is the function of the basement membrane?
Attach to underlying connective tissue
Compartmentalization of epithelium
Filtration of substances to and from connective tissue
Scaffolding for regenerating epithelial cells
What epithelium would you expect to find in the male urethra?
Stratified columnar epithelium
What are the three components of connective tissue?
Cells, Fibers and Ground Substance (fibers and ground substance are part of the ECM)
What are the components of the Extracellular Matrix (ECM)
Collagen fibers, Ground Substance, Reticular fibers, elastic fibers
What are the components of fibers?
Collagen (1-7) and elastic
What are the components of the ground substance?
Proteoglycan aggregates and adhesive glycoproteins
Describe the ratios of loose connective tissue, dense connective tissue, reticular connective tissue and elastic connective tissue in regards to cell and fibers.
Loose: high cell-to-fiber
Dense: low cell-to-fiber
Reticular: low cell-to-fiber
Elastic: low cell-to-fiber
Describe some specialized connective tissue
Adipose, cartilage, bone and blood
Name some embryonic connective tissues?
Mesenchymal connective
Mucous connective tissue
Where is all connective tissue derived?
Mesoderm
Describe the structure of collagen and elastic fibers
Collagen is thick and wavy and elastic is thin, straight branching
Where is loose connective tissue found?
Around muscles, blood vessels, nerves, organs, subcutaneous regions, in the digestive and respiratory tracts
What is the structure of loose connective tissue?
Composed of cells (fibroblasts, mast cells, adipose cells, etc) and ECM (collagen and elastic)
What is the structure of dense regular connective tissue?
Mainly fibers with some ground substance and cells. Fibers are densely packed in parallel bundles of collagen to provide strength in ONE direction
Where is dense regular connective tissue found?
Tendons (muscle to bones), ligaments (bone to bone) and aponeuroses (tendon-like structures that attach muscle to bone)
Describe how dense irregular connective tissue is arranged.
Collagen fibers are arranged in large bundles in DIFFERENT directions. Fibroblasts weave between collagen fibers. Some elastic and reticular fibers are present.
Where is irregular connective tissue found?
Fibrous capsules of organs, deep fascia, dermis, periosteum of bone, perichondrium of cartilage
Describe the structure of dense regular elastic connective tissue
Branching of elastic fibers with sparse collagen fibers. Arranged PARALLEL.
Where is dense regular elastic connective tissue located?
Sheets of elastic tissue such as ligamentum flava and fenestrated membranes like vocal ligaments or large arteries
Describe the structure of reticular connective tissue.
Fibroblasts, type III collagen - thin, branching structure.
What kind of connective tissue requires silver salts/argyrophilic stain?
Reticular connective to see reticular fibers.
What kind of stain would be used to identify reticular fibers?
salts/argyrophilic stain
Describe type I collagen and where it is found in the body.
Most common (gelatin). Found in the dermis, bone, tendons, ligaments, fibrocartilage and capsules of organs
Describe type II collagen and where it is found in the body.
Consists of fibrils dispersed in ground substance. Found in hyaline cartilage and elastic cartilage
Describe the function of type III collagen and where it is found in the body.
Also called reticular fibers. Glycosylated to form fine branching fibers. Found in reticular connective tissue and reticular lamina of basement membrane
Describe type IV collagen and where it is found in the body.
Binds to laminin (adhesive glycoprotein)
Found in basal lamina of the basement membrane
Describe the function of type VII collagen.
Forms anchoring fibrils between lamina densa and lamina reticularis
Describe how tropocollagen becomes muscle.
3 polypeptide chains in a helical configuration become tropocollagen. Tropocollagen overlaps and staggers to become fibrils. Fibrils cross-link side-by-side to form collagen fibers and collagen fibers orient on the same axis to become a bundle. Lots of bundles become tendons and tendons become muscle
What is Marfan’s syndrome?
Autosomal dominant disorder. Tall, long arms, legs, fingers and toes. Dissection of aorta (cause of death) due to proteoglycans between elastic lamellae weakening the aortic wall.
What is the function of adhesive glycoproteins?
Responsible for fastening various components of ECM to one another and to integrins of the cell membrane
Name some proteoglycan aggregates.
GAGs and proteoglycans.
Describe the structure and function of proteoglycans.
Sulfated GAGs form covalent bonds with a core protein to form a proteoglycan. Proteoglycan attaches to hyaluronic acid via link proteins to form aggrecan molecules
Describe the structure and function of GAGs
Linear polymers of repeating disaccharides with sulfate residues (negative charge which attracts cations, etc sodium). High sodium [] increases hydration and resists compression.
Where does the communication of the nuclear pore complex occur?
Where the inner and outer membrane of the nuclear envelope fuse.
Describe telephase.
Cytokinesis (pinching, contractile ring). The nuclear envelope reappears around chromatids.
What is the duration of mitosis dependent on?
The length of the cell.
Describe hypertrophy of cells.
Increase in size of cells in an organ or tissue.
Describe hyperplasia for cells.
Increase in number of cells in an organ or tissue.
Describe characteristics of apoptosis that can be seen visibly on a light microscope.
Pyknosis (chromatin condensing), cell shrinks, cytoplasmic budding (fragments start to appear) and apoptotic bodies (cell fragments with nuclear material appear).
Name some molecules that utilize carrier proteins during diffusion.
Sugars, amino acids, nucleosides.
What kinds of molecules need to be carried across the membrane with a protein molecule?
Large or polar solute molecules.
Why do cells need to use active transport?
Active transport is needed to keep differently charged molecules on different sides of the membrane for cellular volume regulation.
Name the two kinds of passive transport and the two kinds of active transport.
Passive : Simple diffusion and mediated transport.
Active : Primary and Secondary.
Describe the direction of passive transport and active transport.
Passive transport : With the gradient
Active transport : Against the gradient
Describe the energy source of passive transport and active transport.
Passive transport : Uses its own electrochemical gradient.
Active transport : Primary uses ATP and Secondary uses the electrochemical gradient of other molecules.
Describe the kind of membrane proteins in simple diffusion, mediated transport, and primary and secondary active transport.
Simple diffusion does not use membrane proteins. Mediated transport uses pore, channel and carrier proteins. Primary active transport uses ATP, and secondary active transport uses cotransporters or exchangers.
Describe saturability in simple diffusion, mediated transport, and primary and secondary active transport.
Simple diffusion is NOT saturable. Mediated transport and both kinds of active transport are saturable.
What is vesicular transport?
List examples of vesicular transport.
Allows transport across cell membrane of larger particles, requires ATP and multiple organs.
Ex. Nutrient absorption, capillary exchange, immune system.
When fluid is gained in a hypotonic solution, what happens to the ICF and ECF?
ICF: Volume increases, osmolality decreases.
ECF: Volume increases, osmolality decreases
When fluid is gained in a hypertonic solution, what happens to the ICF and ECF?
ICF: Volume decreases, osmolality increases.
ECF: Volume increases, osmolality increases
When fluid is gained in a isotonic solution, what happens to the ICF and ECF?
ICF: Volume and osmolality stay the same.
ECF: Volume increases, osmolality stays the same
When fluid is lost in a hypotonic solution, what happens to the ICF and ECF?
ICF: Volume decreases, osmolality increases.
ECF: Volume decreases, osmolality increases
When fluid is lost in a hypertonic solution, what happens to the ICF and ECF?
ICF: Volume increases, osmolality decreases.
ECF: Volume decreases, osmolality decreases
When fluid is lost in a isotonic solution, what happens to the ICF and ECF?
ICF: Volume and osmolality stay the same.
ECF: Volume decreases, osmolality does not change.
What is a cell?
The basic structural and function unit of a living organism.
What are the components of a cell?
Cell membrane and organelles.
How does oxygen and carbon dioxide get into the plasma membrane.
Passively diffuse.
When a protein is tagged with ubiquitin, what happens to it?
Ubiquitin is a signal for degradation, which means that it is damaged and will be degraded by proteasomes.
What is steroidogenesis?
Production of steroid hormones.
What is thermogenesis and where is this found?
The energy from oxidation is dissipated as heat and converted to ATP. Found in brown fat.
How is f-actin composed?
G-actin, which is the main component of actin, polymerizes to form double-stranded helical filaments (f-actin).
What is actin composed of?
Globular monomers (g-actin)
What are protofilaments?
Longitudinal columns of tubulin subunits.
What are microtubules composed of?
Tubular dimers
What is a centrosome?
A pair of centrioles.
Where is heterochromatin typically found?
Periphery of the nucleus.
Describe how euchromatin and heterochromatin look under an electron microscope.
Heterochromatin appears as course dark granules (basophilic clumps) and euchromatin appears as dispersed granular material and is lightly stained basophilic.
Describe how basic and acidic dyes work in histology and name an example of each.
Hematoxylin (basic dye) is positively charged and bonds with acidic groups.
Eosin (acidic dye) is negatively charged and bonds with basic groups.
What dye would be used to stain phosphate groups in nucleic acid of RNA and DNA?
Basic dyes like hematoxylin.
What dye would be used to stain basic proteins?
Acidic dyes like Eosin.
Why is the nucleolus basophilic?
Basophilia is due to densely concentrated rRNA
What are the steps in interphase?
G1, S and G2
What is mitosis?
Cell division process that results in two daughter cells with the same chromosome number and DNA content as the original cell.
What is karyokinesis?
Division of the nucleus.
What are the three germ layers?
Ectoderm, mesoderm and endoderm.
How is a zygote formed?
When a secondary oocyte unites with sperm.
What is the bilaminar disc composed of?
Epiblast and hypoblast
What is the trilaminar disc?
Composed of ectoderm, mesoderm and endoderm which make up epithelium and glands, connective tissue, muscle tissue and nervous tissue.
Name types of connective tissue proper.
Loose, dense and reticular
Describe the different surfaces that cells have.
Apical, lateral and basal.
Describe apical surface.
Upper free surface exposed to the body exterior or cavity of the internal organ; surface modification (cilia, etc).
Describe lateral surface.
Where adjacent cells interconnect, forming contiguous cells. Has junctions that facilitate adhesion.
Describe basal surfaces.
In contact with underlying basement membrane.
Why do we not bleed when we receive a surface-level laceration?
Epithelia is avascular, meaning that there are no blood vessels.
Describe mesothelium.
Epithelium that lines the body cavities and organs.
Describe endothelium.
Epithelium that lines blood and lymphatic vessels.
What are cell adhesion molecules (CAM’S)?
Responsible for cell-to-cell attachment and cell-to-ECM attachment.
What are the two types of cell adhesion molecules and examples of each.
Calcium dependent molecules: Cadherins and selectins
Calcium independent molecules: Integrins
What is the difference between the two sub-layers of the basal lamina?
There is the lamina lucida which is an electron lucent layer and the lamina densa which is an electron dense layer.
What is the difference between the two sub-layers of the basal lamina?
There is the lamina lucida which is an electron lucent layer and the lamina densa which is an electron dense layer.
What are three kinds of cell junctions?
Tight junctions, anchoring junctions and gap/communication junctions.
What is a tight junction, what is it composed of and where is it located?
Located at apical region. Consists claudins and occludins. Controls the passage of substance between adjacent cells.
Name two kinds of desmosomes that have anchoring junctions.
Belt desmosomes and spot desmosomes (strongest anchoring junction)
What is a gap/communicating junction, what is it composed of and where is it located?
Allows direct passage of signaling molecules from one cell to another. Present where activity of adjacent cells must be coordinated (cardiac muscle, etc).
What is the strongest anchoring junction?
Spot desmosome (maculae adherens)
What is a hemidesmosome?
Anchoring junction found at the basal surface where abrasion may separate epithelium from the basement membrane.
Describe the turnover rate of epithelial tissues.
High turnover rate but depends on location.
What are the two types of glands?
Exocrine and endocine.
What are the two components of exocrine glands?
Secretory and excretory
What are the different kinds of secretory cells in exocrine glands?
Unicellular and multicellular.
Where are simple alveolar excretory ducts found?
Sebaceous glands
Where are simple tubular excretory ducts found?
Intestinal glands
Where are simple coiled tubular excretory ducts found?
Sweat glands
Where are simple branches tubular excretory ducts found?
Gastric and uterine glands
Where are compound tubular excretory ducts found?
Testis
Where are compound alveolar excretory ducts found?
Active mammary gland
Where are compound tubulo-alveolar excretory ducts found?
Parotid gland
What is the function of connective tissue?
Provides the stroma or supportive framework for all the other tissues of the body. Storage of fat. Inflammatory response/tissue repair.
What is mesenchymal connective tissue?
Embryonic connective tissue that consists of mesenchymal cells and ECM. Differentiates into mucous connective tissue and adult connective tissue.
What type of collagen is mucous connective tissue and where is it found?
Type I and III. Forms substance in the umbilical cord.
Describe collagen synthesis.
Cells release procollagen into extracellular space and polymerizes to form tropocollagen. Bundles of tropocollagen form collagen fibrils and the side-by-side cross linking forms collagen fibers.
Why does the skin in older people bounce back slower than that of younger people?
Older people have less elastin which explains why their skin doesn’t bounce back as quickly.
What are the types of Glycosaminoglycans?
Sulfated and non-sulfated GAGS
Describe the difference between Sulfated and non-sulfated GAGS
Sulfated: keratan sulfate, heparan sulfate, heparin.
Non-sulfated: hyaluronic acid
What are the types of adhesive glycoproteins?
Lamin and entactin (derived from epithelial cells), fibronectin, chondronecin and osteonectin (derived from fibroblast, osteoblast, and chondroblast); Tenascinv(derived from glial cells)
Describe fibroblasts, where it is located, etc.
Most common cell in connective tissue proper. Produces collagen and other fibers (ground substance).
Describe mast cells, where it is located, etc.
Found in connective tissue near small blood vessels. Filled with granules. Capable of mitosis.
Describe white or unilocular adipose tissue.
Large spherical cells. Stores fat. Mature fat cell and does NOT undergo mitsosis.
Describe brown or multilocular adipose tissue.
Ready source of fat - oxidation produces heat. Cells are smaller and fat is multilocular.
Describe hyaline cartilage and where it is located.
Most prevalent types of cartilage. Located in articular cartilage of synovial joint, tracheal ring, bronchi, nasal septum, laryngeal and costal cartilage.
Describe elastic cartilage and where it is located.
Found in structures that must withstand repeated bending such as external eat, auditory tube and epiglottis.
Describe fibrocartilage and where it is located.
Located where dense connective tissue bends into hyaline cartilage such as intervertebral discs, articular discs and pubic symphysis.
What are the components of hyaline cartilage.
ECM, chrondrocytes and perichondrium
Where are mast cells derived from?
Derived from stem cells in the bone marrow.
What do the granules within mast cells contain?
Histamine, heparin, and chemotactic mediators (cytokines).
What kinds of molecules are released from the mast cell membrane.
Leukotrienes and prostaglandins.
What is the extracellular matrix?
non-cellular component present in all tissues.
What are glycoproteins?
Proteins conjugated with variable amounts of covalently linked oligosaccharides. 90% protein, 10% carbs
What are leukrotriens and where are they released?
Released from the mast cell membrane and cause vascular permeability and smooth muscle contraction.
What are prostaglandins and where are they released?
Released from the mast cell membrane and causes bronchospams and mucous secretion
What are histamines and where are they located?
Within granules in mast cells. Cause vasodilation, increase capillary permeability, brnchospasm and mucous secretion.
What is heparin and where is it located?
Within granules in mast cells. Heparin is an anticoagulant.
What is the function of chemotactic mediators?
Attract monocytes, neutrophils, basophils and eosinophils.
How are new adipose cells derived?
From mesenchyme cells or fibroblasts.
Describe the function of adipose tissue.
Efficient form of calorie storage, shock absorber, provides mobility and prevents heat loss. Is also a source of water in extreme conditions.
What are the components of elastic cartilage.
Same as hyaline cartilage (ECM, chrondrocytes and perichondrium) but with elastic fibers.
What are the components of fibrocartilage?
Same as hyaline cartilage (ECM, chrondrocytes and perichondrium).
What type of cartilage is fibrocartilage?
Type I
What type of cartilage is repair cartilage?
Type I and II
What is the function of the ECM?
Provides essential physical scaffolding and initiates important biochemicanl and biomechanical cues that are required to maintain homeostatisis.
What is the function of glycoproteins?
Cell surface recognition, cell surface antigenicity.
How are carbohydrates linked in glycoprotein oligosaccharides?
Covalently linked by N-or O-glycosyl bonds.
How are N-glycosyl and O-glycosyl bonds formed?
N-glycosyl bonds (nitrogen bond) are formed between sugar and asparagine. O-glycosyl (hydroxyl bond) bonds are formed between sugar and serine or theonine.
What are the two broad classes of N-linked carbohydrates?
Complex oligosaccharides and high mannose oligosaccharides.
Describe the synthesis of O-linked glycoproteins and proteoglycans.
- Glycosylation via addition of N-acetylglucosamine to specific seryl or threonyl group (occurs in the lumen of the ER)
- Sugars linked to each other through glycosidic bonds formed by glycosyltransferases (membrane bound enzymes of ER and golgi)
What does o-linked synthesis rely on?
Specificity of glycosyltransferases (NOT coded by DNA),
Where is the energy for o-linked synthesis reaction derived from?
Nucleotide sugars.
Describe the synthesis of N-linked glycoproteins and proteoglycans.
- An oligosaccharide containing N-acetylglucosamine, mannose, and glucose is linked to dolicol pyrophosphate through pyrophosphate linkage
- That oligosaccharide is transferred to the protein via a protein-oligosaccharide transferase
- Mannosyl and glycosyl residues are removed as it passes through the ER
- Oligosaccharide chain is completed in the Golgi (addition of carbs for complex class, nothing for high mannose class)
What is the structure of GAGs?
Located on cell surface or in ECM. Glycosaminoglycans (GAGs) are negatively charged, long, unbranched heteropolysaccharide chains generally composed of a repeating disaccharide unit (acidic sugar-amino sugar)
What is the function of GAGs?
Shock absorber due to large number of negative charges surrounded by a shell of water molecules (water goes in and out with external force).
Slippery consistency of mucous secretions and synovial fluid produced by the negative charges slipping past each other like magnets with the same charge.
Describe the structure of proteglycans.
GAG covalently attached to proteins (much more carb than protein). Many can carry 2 types of GAG chains
Describe the function of proteglycans.
Lubricants and support elements of connective tissue which allows stabilization and support while maintaining water and salt balance. When in close proximity to each other, they slip past each other like 2 magnets w/ same polarity (large number of negative charges), produces slippery consistency.
Where do proteoglycans synsthesize?
RER, protein is glycoslyated as it passes through the Er. Carb chain begins with the synthesis of linkage region followed by the addition of 2 galactose residues.
When does sulfation occur?
After target carb has been incorporated to growing chain.
Define scruvy and its etiology.
Vitamin C deficiency.
Collagen fiber strength degraded.
Can show bruises on limbs as a result of subcutaneous extravasation of blood (capillary fragility).
Can lead to things like gum disease and loose teeth.
What are some collagen disorders.
Osteogenesis Imperfecta.
Ehlers-Danlos IV-VII
Describe Osteogenesis Imperfecta
Brittle bone disease. Disorder of Type I collagen.
Describe Ehlers-Danlos VI.
Lysyl hydroxylase is deficient.
Type I and III collagen are synthesized with decreased hydroxylysine and cross linking is less stable (lysine and allysine occurs but not as stable).
Hyperextensibility of the skin and joints (pull skin far away), poor wound healing, musculoskeletal deformities.
Describe Ehlers-Danlos VII.
Skin bruises very easily and is hyperextensible.
Dislocations of major joints like knees and hips.
Laxity of ligaments is caused by incomplete removal of the amino-terminal propeptide of procollagen chains.
Describe Ehlers-Danlos IV.
Defects in Type-III collagen (important in skin, arteries, hollow organs).
Translucent skin, easy to see veins, marked bruising, sometimes appearance of aging in hands and skin.
Problems can arise from arterial ruptures, intestinal perforation, rupture of uterus during labor or pregnancy. Repair is hard b/c of tissue fragility.
Describe the differences between type I and type II osteogenesis imperfecta.
Type I: Early childhood fractures,
Modified Alpha-I chain deletions,
Cannot make normal collagen triple helix, and protein cannot leave the cell,
Leads to protein suicide
Type II: More severe, death in utero;
Glycine is substituted for another AA;
Glycine normally fits in the interior of the collagen triple helix, so these substitutions destabilize the helix
Describe the primary structure of the unique amino acid in collagen.
Distinctive repeated sequence (Gly-X-Y): X is proline and y is 5-hydroxyproline.
Describe the sequence for left and right handed helix in the amino acid composition of collagen.
Left: The sequence produces conformation of a LEFT HANDED HELIX with 3.3 residues per turn (10Å/turn)
Right:Gly at every third position allows for 3-member superhelix (right handed)
What is one of the first events of the biosynthetic pathway for collagen?
One of the first events is the hydroxylation of proline and lysine found in the Y-position of Gly-X-Y
Where are the precursors of the collagen molecule formed?
formed in fibroblasts (or in the related osteoblasts of bone and chondroblasts of cartilage) and are secreted into the ECM
What are the requirements of hydroxylation of collagen?
Hydroxylation requires Oxygen and Ascorbic Acid (Vitamin C):
Prolyl hydroxylase,
Lysyl hydroxylase,
Vit C needed for hydroxylation for cross linking of collagen
What is needed for hydroxylation for the cross-linking of collagen?
Vitamin C
Why is hydroxylation needed for the synthesis of collagen?
Without hydroxylation, collagen fibers cannot cross-link. The tensile strength of the assembled fiber will be reduced.
Describe the synthesis of GAGs and Proteoglycans.
Proteoglycansynthesis in RER, core protein is glycosylated as it goes through ER, carb chain synthesizes, and sulfation occurs after target carb is incorporated into growing chain.
Detail the biosynthetic pathway for collagen.
Hydroxylation. Procollagen formation, translocation to golgi. Vesicles release procollagen to ECM and cleaves N and C terminals (tropocollagen). Tropocollagen becomes fibrils and arrange to form collagen.
What is the role of lysyl oxidase in collagen synthesis.
Copper containing enzyme - oxidatively deaminates some lysyl and hydroxylysyl residues in collagen.
Forms covalent bonds and achieves tensile strength.
Why is copper needed in lysyl oxidase?
to do reactions that create covalent bonds instead of H-bonding by lysyl and hydroxylysyl residues
