3- Cell Biology Review

Cell

basic structural & functional unit of life

Components of the Cell

• plasma membrane

• nucleus

• cytoplasm

Plasma Membrane

separates internal & external environment, outer boundary, area of connection to other cells, facilitates communication, outside PM = another cell/ECF

• functions

  • boundary (ICF & ECF)

  • encloses & supports

  • attaches to nearby cells

  • communication & recognition

• phospholipid bulayer containing cholesterol, proetins attached/embedded

  • polar/hydrophilic heads (out) & nonpolar/hydrophhobic tails (in)

• fluid mosaic model

• contains cholesterol

• molecules need help to pass through membrane

  • nonpolar = easy pass, polar & large = help

• diffusion possible w/ gases (CO2, O, He), steroids (lipophilic), H2O

• everything channel or transporter to get through, large, polar

• selectively permeable, allow some things throug & not others

Nucleus Overview

in center of cell, controls cellular activity, brain of cell, has genetic material & guidelines for proteins to make

Cytoplasm

area between PM & nucleus, contain organelles performing specific roles

What are some cellular functions?

• synthesize molecules (proteins, nucleic acids, lipids)

• communicate

• reproduce

Membrane Lipids

• phospholipids, bilayer, polar heads face externally & internally (hydrophilic), nonpolar tails meet in the middle of the membrane (hydrophobic)

• cholesterol, more = less rigid

Membrane Protein Types

• integral - deep in lipid bilayer, some extend full thickness, transmembrane proteins, act as transporters, ions are specialized

• peripheral - attach to inner/outer surface of lipid bilayer, not part of membrane (glycoprotein)

Glycoproteins/Glycolipids

• identification & communication, distinguish between self & foreign

• sperm needs to recognize oocyte

• membrane protein - marker

Channel Protein

• membrane protein - transport

• hydrophobic to hydrophobic, outward facing, hydrophilic liner)

Carrier Proteins

• membrane proteins - transport

• specificity - single type of molecule/shape

• compete for similar shapes

• saturation - transport rate depends on number

ATP Powered Pumps

• have binding sites for specific ions/mols & ATP

• hydrolysis of ATP → ADP = E release to change shape of carrier to move substance across the membrane

• ion & P released, pump back to OG shape

What are the cell transport mechanisms?

• passive- no E input (diffusion, osmosis, facilitated)

• active- needs E input (low → high conc)

• vesicular- use vesicles to move things in/out, needs E input (endo/exocytosis)

Diffusion

• net movement from areas of high → low conc

• PASSIVE, DOWN conc gradient, release E

• transports lipid-soluble mols

• ex → O2, CO2, lipids, O2/CO2 diffuse across alveoli in lung

Osmosis

• PASSIVE

• water diffuses across selectively permeable membrane, down conc gradient

• NOT SOLUTE MOVING

• transports water

• ex → water movement from intestines into blood

• hypotonic → right solute concentration is greater

• hypertonic → left solute concentration lower

• equilibrium → solutes evenly distributed across compartments.

Facilitated Diffusion

• PASSIVE

• carrier proteins move substances across PM w/o ATP, has specificity, sautration, competition, down conc gradient

• E released

• transports large substances w/ membrane channels, ion & small mol w/ membrane channels

• ex → glucose movement into muscle cells & adipocytes

Active Transport

• ACTIVE

• ATP powered pumps bind to substances, move across PM, use ATP/input

• move up concentration gradient, low → high

• use transsport protein carrier,a ct as pump

• transports substances accumulated in concentrations higher on 1 side of memb than other

• ex → ions (Na, K, Ca)

Secondary Active Transport

• ions moved across PM by active transport = ion conc gradient

• USE ATP

• ions move back down gradient w/o ATP, facilitated diffusion

  • symport → another ion/mol moves w/ diffusion ion

  • antiport → another ion/mol moves in opposite direction

• transports sugars, aa, ions

• ex → glucose into intestinal epithelial cell w/ Na conc gradient

Endocytosis

• vesicular transport, vesicle taken into cell, use ATP

  • receptor mediated → specific substances

  • phagocytosis takes in cells & solid particles, cell eating

  • pinocytosis takes in mol dissolved in liquid, cell drinking

• ex → immune system cells ingest bacteria & cellular debris, most cells take in substances w/ pino

Exocytosis

• secretory vesicles fuse w/ PM, release contents to outside cell, use ATP

• move mol OUT of cell

• transport proteins & other water soluble mol

• membrane of vescile becomes part of PM

• ex → digestive enzymes, hormones, neurotransmitters, (exocrine, outside cell body), (endocrine , into blood)

Cytoplasm

• liquid content inside cell, organelles float, cytosol = fluid

• made of water, electrolytes (Na, K, Cl), glucose, aa

• remove waste products, aid in cell resp, holds cell shape

Cytoskeleton

structural support, generates movement

• microtubules → made of tubulin, intracellular movement, make centrosome for cell division, flagella, cilia, dynamic instability, hollow center

• microfilaments → actin, movement & support, muscle contraction

• intermediate filaments → strength & stability

Nucleus

• surrounded by nuclear envelope w/ nuclear pores, allow mols to go from nuc to cytoplasm (selectively permeable), contain DNA, chromatin

  • chromatin → dispersed, thin strands of DNA & proteins, condenses to become visible mitotic chromosome, 1+ nucleoli, dense bodies consiting of ribosoma; RNA & proteins

• control center of cell, DNA w/in nuc regulates protein synthesis & chem rxns of ecll

Ribosomes

• sites of protein synthesis, found on rough ER or free floating

• ribosomal RNA & proteins form large & small subunits

• soem on rough ER, others are free in cyto

Endoplasmic Reticulum

• close to nuc

  • rough → studded w/ ribos, protein synthesis, membranous tubules & flattened sacs w/ attached ribosomes

  • smooth → steroid hormone synthesis, cell detox, Ca store, membranous tubules & flattened sacs w/ NO attached ribosomes

Golgi Apparatus

• sites of protein synthesis & mod, flattened sacs, pack proteins, secretory vesicles bleb off to move mol (distribution center)

• flattened embrane sacs stacked on e/o

Mitochondria

• powerhouse of cell, cell resp (provides ATP), cristae infolfings, enzyme of ETC kreb’s citric acid, stress causes increases in process

• spherical rod shaped, threadlike structures, enclosed by double membrane, inner membrane makes cristae

Secretory Vesicles

• pinch off golgi to cell membrane & exocytosis occurs, ATP needed

Lysosomes

• suicide sacs, have hydrolytic enzymes, digest phagocytized material

• autophagy → digest dysfunctional organelles

• membrane bound vesicle pinched off golgi

Peroxisomes

• have enzymes that break down fatty acids & aa to H2O2, then broken down by catalase into H2O & O2, found in liver & kidney cells (high filtration areas)

Proteasomes

• tubelike protein complexes in cyto

• break down proteins in cyto

Centrioles

• pair of cylindrical organelles, triplets of parallel microtubules

• in centrosome, area of cyto where MT formation occurs

• serve as centers for MT form, determine cell polarity during cell division

• form basal bodies of cilia & flagella

Cilia

• hair seen on surface of cells, able to move, mucus in area to trap microbes

• extensions of PM, w/ doublets of parallel MT

• ex → bronchioles, trachea, female reproductive tracts

Flagella

• long projection, seen on sperm cells, allow movement for fertilization

• extensions of PM, w/ doublets of parallel MT

Microvilli

• projection on apical/top surface of cells

• surface looks fuzzy/tiny

• increase SA in areas of absorption

• seen in intestine, kidneys, other absorption areas

• extensions of PM containing microfilaments

Intracellular Fluid

• fluid in the cyto, largest fluid compartment

• 2/3 of body fluid, 25L

Extracellular Fluid

fluid outside cells, 1/3 bodily fluid/15L

• 80% of ECF is interstitial fluid, includes lymphatic vessels collect IF & bring to heart to reenter bloodstream, fluid not inside cell just hanging out, leak out of capillaries to remove extra

• 20% of ECF makes up plasma volume in bloodstream (3L in blood)

• also have CSF & synovial fluid in joints