Chapter 3: Cell Biology

AP1 Chapter 3 1 I. Fxns of a cell • Cell – the basic unit of all living things (the smallest part of a living organism in our case humans) • Shared Characteristics – Plasma • Outer boundary of the cell though which the cell interacts with its external environment – Nucleus • Directs activities of the cell – Cytoplasm • Most cell activities occur here – Organelles • Perform specific fxns in cell

AP1 Chapter 3 2 4 major fxns of cells I. Fxns of a cell A. Cell metabolism & e+ use: – Metabolic rxns in the cell  e+ is released to accomplish cell activities & maintain Body Temp. B. Synthesis of Molecules – Can prod proteins, nucleic acids, lipids – Cell’s fxn & characteristics are determined by the molecules they prod C. Communication – Cells prod & respond to chemical & e+ signals wh/ allows them to communicate w/each other – * Neuron to a muscle = contraction or relaxation D. Reproduction & inheritance – Cell holds the genome. It determines structure & fxnl characteristics of that cell. – Cells can prod new cells – Gametes transmit genetic info. AP1 Chapter 3 3 III. Plasma Membrane

AP1 Chapter 3 4 III. Plasma Membrane

• Outer most component of the Make-up: cell • 45-50% Lipids • Fxns as a boundary to • 45-50% Proteins separate inside from outside of • 4-8% Carbohydrates the cell (intra vs extra cellular) • Encloses and supports the cell’s contents • Attaches the cell to the extracellular environment or to other cells • Cell’s ability to recognize & communicate with each other occurs via the plasma membrane • Determines what moves into ot • Membrane potential: electrical out of the cell (therefore the charge difference across the contents inside the cell can be PM resulting from the cell’s different from what is outside). regulation of movement into and out of the cell

AP1 Chapter 3 5 III. Plasma Membrane • • Glycocalyx Terminology – – – – – – – cell ofthe the outside the inside verses Membrane Potential Glycolipids Glycoproteins Intercellular Extracellular Intracellular the outeron surfacethe plasma of membrane glycoproteins,Collection of glycolipids, and :

: : (Inter : (Intra- Carb’s : (Extra: : carb’s -

+ Lipids Between) from 1 cell 1 cell to another fromBetween) inside Inside) the cell - : result of uneven distribution of ions ofions on distribution ofuneven: result

Outside) outside ofthecell Outside) outside + proteins

carb’s

that lies 6

IV. Membrane Lipids

AP1 Chapter 3 7 IV. Membrane Lipids AP1 ChapterAP1 3 • • Phospholipids (PL’s): Cholesterol – – – – – Predominant lipid in membrane in lipid Predominant ring is embedded in thetails in embeddedring is headwhile the in embedded “tail” is andthe It is bipolar also providing stability for the PM tolimit PL’sHelps mvmt btwnand lie PL’s membraneup 1/3ofthe Makes Bipolar: • • together between the heads between together and non- hating Hydrophobic surfaces (inner & outer) loving andpolar and faces both Hydrophilic

“head” is water “head”

“tail” is“tail” water polar and crowd polar

8

IV. Membrane Lipids

• *Fluid Mosaic Model* – The lipid bilayer is mobile with things floating w/in it – Consequences of this: a) Important for molecule distribution in the membrane b) Slight damage can be repaired because the PL’s will move to cover it c) It enables two different to fuse with each other

AP1 Chapter 3 9 V. Membrane Proteins A. Marker Molecules B. Attachment Proteins C. Transport Proteins D. Receptor Proteins E. Enzymes

AP1 Chapter 3 10 V. Membrane Proteins (MP)

• Many fxns of the plasma membrane are determined by the combination of membrane proteins present. • The ability of these proteins to fxn properly is determined by their 3-D shape • There are 2 major types: 1. Integral/Intrinsic • (Transmembrane) contain hydrophobic and hydrophilic regions to match the phospholipids characteristics & location 2. Peripheral/Extrinsic • Surface proteins on inner or outer surface. • Can be bound to an integral protein or the phospholipids head • There are 5 major classes of MP’s

AP1 Chapter 3 11 5 major classes of Membrane proteins

I. Marker II. Attachment III. Transport IV. Receptor V. Enzymes molecules Proteins Proteins Proteins

B A B ATP powered Proteins A Channel C Proteins Carrier Carrier Receptors linked to to linked Receptors to linked Receptors channel proteins pump G - proteins

Channel a Non b G

Channel ated

aUniporter bSymporter c - gated

Ligand - i Voltage - ii channel channel gated gated

AP1 Chapter 3 12 Membrane Proteins: I. Marker Molecules

• Glycoproteins or glycolipids that allow for cells to identify other cells or other molecules • Important because cells aren’t isolated and must function as a whole for normal body function. • May be integral or peripheral proteins • Ex/ immune cells

AP1 Chapter 3 13 Membrane Proteins: II. Attachment Proteins

• Integral proteins that may attach to intracellular molecules. • Integrins can also function in cellular communication.

AP1 Chapter 3 14 Membrane Proteins: III. Transport Proteins All exhibit 3 characteristics 1. Specificity – Each binds to & transports only 1 types of molecule/ion 2. Competition – Closely related substances may bind to the same binding site & the one w/ greater [ ] or higher affinity is more readily moved across the PM 3. Saturation – Movement is limited by the # of transport proteins rate will eventually plateau because the # of proteins are going at

AP1 Chapter 3 their maximum rate 15 Membrane Proteins: III. Transport Proteins A. Channel Proteins • Form passageways through the plasma membranes that have both hydrophobic and hydrophilic regions. B. Carrier Proteins • Move larger ions or molecules across the membrane, when bound it changes shape to allow it to move from one side of the membrane to the other then return to its original shape to work again. C. ATP-powered pumps • Moves ions or molecules across the membrane using ATP.

AP1 Chapter 3 16 Membrane Proteins: III. Transport Proteins A. Channel Proteins a. Non -gated Channels • Always open responsible for the permeability of the plasma membrane when the at rest. b. Gated Channels • Can be opened or closed i. Ligand Gated – Small molecules must bind in order to open or close the channel ii. Voltage Gated – Change in voltage across the plasma membrane causes the gate to open AP1 Chapter 3 17 Membrane Proteins: III. Transport Proteins B. Carrier Proteins a. Uniporter • Movement of 1 ion or molecule across the plasma membrane. b. • Movement of 2 ions or molecules in the same direction (into the cell or out of the cell). c. Antiporter • Movement of 2 ions or molecules in opposite directions (one in and one out or vise versa).

AP1 Chapter 3 18 Membrane Proteins: III. Transport Proteins C. Sodium-Potassium Pump

• These have 2 binding sites. One is for the molecule to be moved the other is for ATP • Breakdown of ATP releases e+ ∆ing shape of the “pump” protein which moves the molecule across the membrane

AP1 Chapter 3 19 Membrane Proteins: IV. Receptor Proteins

• Proteins or glycoproteins in the plasma membrane that have an exposed receptor site on the outer cell surface which can attach to specific chemical signals. • Many are part of an intercellular communication system that coordinates cell activities.

AP1 Chapter 3 20 Membrane Proteins: IV. Receptor Proteins A. Receptor linked to channel proteins – These help form ligand- gated channels & when bound it changes the channels shape to move ions B. Receptors linked to G- protein complexes – Uses a second messenger system, binding of the receptor externally causes to the cell internally • 3 ways α can stimulate a cellular response 1. Intracellular chemical signals 2. Opening channels in the plasma membrane 3. Activation of enzymes AP1 Chapter 3 associated with the plasma membrane 21

Membrane Proteins: V. Enzymes

• These may work on the inner or outer surface of the plasma membrane. • Some are always active but others are activated by things like GPCR’s

AP1 Chapter 3 22 VI. Movement through the plasma membrane

AP1 Chapter 3 23 V. Mvmt thru the PM • Inside of the cell: – Enzymes other proteins, glycogen, high potassium concentration • Outside of the cell: – High concentration of sodium, calcium, & chloride • The cell has to be able to bring in nutrients inside and get waste products out without changing the cell’s volume, because too much can cause the cell the rupture (causing cell death) or to shrivel (also causing cell death).

• Movement 1. Molecules that are lipid soluble or very small water soluble molecules will freely go across the plasma membrane. 2. Large lipid soluble molecules and water soluble molecules can’t pass through the plasma membrane and may need to use transport proteins. 3. Larger water soluble molecules or whole cells may be moved by vesicles. AP1 Chapter 3 24 mechanisms

A. Mechanisms B. Mechanisms • No energy required to • Energy required to move move molecules from one molecules from one side side of the membrane to of the membrane to another another

AP1 Chapter 3 25 Membrane transport mechanisms

Passive Transport Mechanisms Active Transport Mechanisms A. Diffusion A. Active Transport B. Osmosis B. Secondary Active C. Transport C. Vesicular Transport a. b.

AP1 Chapter 3 26 Passive Transport Mechanisms A. Diffusion: – Movement of solutes from an area of high concentration to an area of low concentration – Concentration gradient: concentration difference between 2 points divided by the distance between the 2 points, – Rate of Diffusion 1. Magnitude of the concentration gradient 2. Temperature of the solution 3. Size of the diffusion molecules 4. Viscosity of the solvent

27 AP1 Chapter 3 Passive Transport Mechanisms B. Osmosis – Diffusion of water across a selectively permeable membrane – Will allow water but not all solutes with in the water – Important because it can influence a cell’s function when water moves. – Osmotic Pressure: • Force required to prevent water movement across a selectively permeable barrier via osmosis 1) Isosmotic 2) Hyperosmotic Concentration 3) Hyposmotic of solutions

AP1 Chapter 3 28 Passive Transport Mechanisms B. Osmosis

• Tonicity : refers to the cell’s shape remaining constant b/c it maintains it’s internal pressure 1. Isotonic sol’n: no net mvmt of H2O, cell doesn’t ∆ shape 2. Hypertonic sol’n: mvmt out of cell b/c sol’n has a greater [ ] of solute thus a higher osmotic pressure (crenation) 3. Hypotonic sol’n: mvmt into cell b/c sol’n has a lower [ ] of solute thus a lower osmotic pressure (Lysis)

AP1 Chapter 3 29 Passive Transport Mechanisms C. Facilitated Diffusion – Amino acids & glucose go into the cell and area going out of the cell can’t occur via direct diffusion because they are too big. Thus there is – Mediated transport (facilitated diffusion): • Process by which transport proteins assist the movement of water soluble molecules or electrically charged molecules or ions across the plasma membrane.

30 AP1 Chapter 3 Active Transport Mechanisms

A. Active Transport • also a type of mediated transport. Requires energy provided by ATP movement dependent on the number of pumps and availability of ATP. • Important because it can move things against their concentration gradients.

AP1 Chapter 3 31 Active Transport Mechanisms

B. Secondary Active Transport • Passive transport of 1 molecule with its concentration gradient helps to energize the carrier so that it can transport the second molecule against its concentration gradient.

AP1 Chapter 3 32 Active Transport Mechanisms

C. Vesicular Transport • Movement of larger volumes of substances across the plasma membrane through the formation and release of vesicles requiring ATP. • BUT…the specificity seen in others doesn’t occur in this process. a. Endocytosis i. ii. iii. Receptor mediated endocytosis b. Exocytosis

AP1 Chapter 3 33 Active transport mechanisms

a) Endocytosis: uptake of material into the cell.

Pinocytosis • 3 types:

i. Pinocytosis • Molecules dissolved in liquid

ii. Phagocytosis Phagocytosis • Cells and solid particles iii. Receptor mediated

endocytosis - mediated • Specificity for substances Receptor AP1 Chapter 3 34 Active Transport Mechanisms b. Exocytosis – Materials manufactured by the cell are packaged in secretory vesicles that fuse w/the PM & release their contents outside of the cell – ATP req’d – Proteins & other water soluble substances

AP1 Chapter 3 35 VII. Cytoplasm

The material outside the nucleus and inside of the plasma membrane

AP1 Chapter 3 36 http://www.animalcute.net/wp-content/uploads/2012/01/Animal-Cell-Cytoplasm5.jpg VII. Cytoplasm (1/2 cytosol/1/2 organelles) 3 parts to cytoplasm 1. Fluid Portion 2. Cytoskeleton 3. Cytoplasmic • Anatomy: • Supports cell & Inclusions – H2O w/dissolved holds nucleus & • Anatomy: ions & – Collections of molecules; organelles in place molecules colloid w/many • Responsible for manufactured or suspended mvmt in & of the ingested by cell molecules and may be espicially cell membrane bound proteins • Made up of 3 • Physiology • Physiology: groups of proteins: – Fxn is dependent – Contains enz’s a) Microtubules on the molecules that catalyze – Ex: energy storage decomposition & b) Microfilaments  lipids&glycogen synthesis rxns, ATP is also c) Intermediate prod’d in filaments glycolysis rxns AP1 Chapter 3 37 VII. Cytoplasm • 2. Cytoskeleton • Made up of 3 groups of proteins: a) Microtubules • Provide support & structure to cytoplasm • Involved in cell division & transport of intracellular materials • Form essential components of organelles (centrioles, spindle fibers, cilia, & flagellum) b) Actin Filaments • Provide structure to cytoplasm & mechanical support for microvilli • Responsible for cell mvmts c) Intermediate filaments • Protein Fibers • Provide strength to cells 38 VIII. The Nucleus & Cytoplasmic Organelles A. Nucleus G. Peroxisomes B. Cytoplasmic H. Proteosomes Organelles: I. Mitochondria A. Ribosomes J. Centrioles & Spindle Fibers B. Endoplasmic Reticulum K. Cilia & Flagella C. Golgi Apparatus L. Microvilli D. Secretory Vesicles E. Lysosome • Organelles: structures w/in cells that are specialized for a particular fxn. • Number & types within each cell are related to the specific structure & function of the cell • Largest organelle  Nucleus • (all others are considered cytoplasmic organelles)

AP1 Chapter 3 39 VIII. The Nucleus & Cytoplasmic Organelles A. Nucleus • Large membrane bound structure usually centrally located – Shape & # of lobules vary dependent on cell type (may be multiple or spit out of cell) – 3 Major structures of the nucleus:

AP1 Chapter 3 40 IX. The Nucleus & Cytoplasmic Organelles

A. Nucleus 41 that

templates,&

rRNA

proteins that serve serve asthe that proteins ribosomal for site assembly subunits contain the the contain 1 densebodies ormore , of consisting ribosomal RNA called DNA of stretches 10 nuclear organizerregions Thin strands of DNA wound DNA of strands Thin that around (proteins) histones thus synthesis protein regulate chemical the regulating also cell the in rxns Double Double enclosing membrane the separates that nucleus the the cytoplasm, nucleusfrom also to usesnuclearpores of the in/out mvmt regulate nucleus

Nucleolus

Chromatin Nuclear Envelope

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– nucleus 3 Major structuresof the

3.

2.

1. • IX. The Nucleus & Cytoplasmic Organelles B. Ribosomes C. Endoplasmic Reticulum • rRNA & proteins make-up both • Series of membranes the large & small subunits of continuous w/ the nuclear ribosomes envelope distributed throughout the cell • Site of protein synthesis • 2 major types: • 2 categories: – Rough ER: ribosomes attached 1. Free: mainly prod proteins that fxns in protein synthesis & will be used inside the cell transport of those to the golgi – Smooth: no ribosomes fxns in 2. Bound: mainly prod proteins manufacture of lipids & carb’s; that will be excreted from the detoxifies harmful chemicals; can 2+ cell store Ca

AP1 Chapter 3 42 IX. The Nucleus & Cytoplasmic Organelles D. Transport Vesicle F. Secretory Vesicle • membrane bound sack from • Membrane bound sac that the ER that goes to the GA pinches off of the GA that for processing carries the finalized proteins & lipids to the cell surface for secretion • These can accumulate in the cell until proper signal is received to initiate its E. Golgi Apparatus (GA) release • Flattened membrane sacs stacked on each other modifies, packages, & distributes proteins & lipids prod’d by RER & SER for secretion or internal use • Can concentrate, or chemically modifies by adding carbs or lipids making glycoproteins or glycolipids AP1 Chapter 3 43 IX. The Nucleus & Cytoplasmic Organelles

F. Lysosome G. Peroxisome • Membrane bound sac • Membrane bound vesicle pinched off of GA carries 1 site of fatty acid & AA digestive enz’s that can degradation byproduct

break down NA, is H2O2  using catalase polysaccharides, lipids, brksdwn to H2O + O2 thus old cell parts & • High # in liver & kidney phagocytized bacteria cells

AP1 Chapter 3 44 IX. The Nucleus & Cytoplasmic Organelles H. Proteasome I. Mitochondria • Tube-like protein in the • Dynamic structure cytoplasm as proteins enclosed by a double enter the cell they are membrane. Inner enzymatically degraded projections are called cristae. Major site of in the cytoplasm ATP-synthesis when O2 is available. • #/cell  based on cell fxn

AP1 Chapter 3 45 IX. The Nucleus & Cytoplasmic Organelles

J. Centrioles K. Cilia • Pair of cylindrical • Short hair-like Extensions of organelles in centrosome the PM using microtubules made-up of microtubules to hold their shape • Center for microtubule • Fxnally in humans it moves formation materials over cell surface • Determine polarity of the cell during division • Basal Body: located at base • For basal bodies of cilia & of cilia flagellum

AP1 Chapter 3 46 IX. The Nucleus & Cytoplasmic Organelles L. Flagellum • Long Hair-like extensions M. Microvilli of the PM using • Short extension of the PM microtubules to hold their containing microfilaments shape. • Increase surface area of the PM for absorption or • Responsible for the mvmt secretion. of sperm • May fxn as a modified sensory receptor (hair cells in ear)

AP1 Chapter 3 47