DAT: 3.1-3.8 Cells & Organelles

• 2 layers

• makes up majority of cell membrane

• composition:

  • 2 fatty acids & phosphate head attached to glycerol backbone

  • phosphate head hydrophillic

  • fatty acid hydrophobic

  • made by smooth ER

  • amphipathic

Phospholipid bilayer

• CAN cross membrane

• ex) O₂, CO₂, N₂, Steroid Hormones

Small, Hydrophobic Molecules

• CANNOT cross membrane

• ex)H⁺, Na⁺, HCO₃^-, K⁺, Ca²⁺, Cl^-, Mg²⁺

Ions

• CANNOT cross membrane

• ex) Glucose, Sucrose

Large, Uncharged, Polar Molecules

• CAN cross membrane

• ex) H₂O, Urea, Glycerol, NH₃

Small, Uncharged, Polar Molecules

• Embedded in the cellular membrane

• transmembrane protein is a type of _

Integral membrane protein

Loose attachment to the cellular membrane

Peripheral membrane protein

describes the cellular membrane as a _ of different parts (phospholipids, membrane proteins, etc.)

Fluid Mosaic Model

Movement down concentration gradient; NO energy required

Passive transport

• Movement of small, uncharged, nonpolar molecules directly through the membrane (e.g., O₂, CO₂).

• slip through

Simple diffusion

• passive movement of water down its concentration gradient, across the cellular membrane

• ex) in solution of water & salter, WATER will move in order to reach equilibrium

Osmosis

• Movement of large, polar, or charged molecules via membrane proteins

• ion passing through an ion channel in the cellular membrane to move from an area of higher concentration to an area of lower concentration

Facilitated diffusion

One molecule, one way

Uniport

Several molecules, one way

Symport

Several molecules, opposite ways

Antiport

• hollow tubes substances move through

• ex) aquaporin allow movment H2O across

Channel protein

• binds to specific molecules so it can pass across membrane

• changes physical shape after binding to a specific molecule

• transports POLAR molecules

• requires ATP to function

Carrier protein

• Nonspecific channel protein for hydrophilic molecules

• used to transport water quickly across a cell membrane

Porin

Channel protein allowing rapid water transport.

Aquaporin

Uses energy to move particles against their concentration gradient

Active transport

• Use of ATP to directly move particles against concentration gradients

• e.g., sodium-potassium pump

Primary active transport

• Uses energy of a molecule moving down its concentration gradient

• Use of indirect energy to move particles against concentration gradients

Secondary active transport

Bulk transport using vesicles; energy required.

Cytosis

• Cell engulfs material into VESICLES, requires ATP

• extracellular substances are incorporated into the cell by being enfolded and surrounded by a vesicle

• Types: phagocytosis, pinocytosis, and receptor-mediated _

Endocytosis

• substances in vesicles are released from the cell by the vesicle fusing with the plasma membrane

• commonly triggered by an increased Ca²⁺ concentration within the cell

• (e.g. occurs before neurons releasing neurotransmitters)

Exocytosis

• “Cell eating”; takes in solids.

• use to internalize pathogens

Phagocytosis

• “Cell drinking”; takes in dissolved solutes

• invagination of the plasma membrane around liquid or dissolved material is called

Pinocytosis

• Specific molecule binds receptor to trigger vesicle formation.

• process which requires energy to occur

Receptor-mediated endocytosis

• Membrane bound organelles

• nucleus & organelles

Eukaryotes

• NO membrane-bound organelles

• ribosomes appear in all _

Prokaryotes

All contents inside cell membrane.

Cytoplasm

Intracellular fluid portion of cytoplasm.

Cytosol

• used to store and protect the DNA in the eukaryotic cell

• contains:

  • cells genetic material

  • nuclear envelope

  • nucleolus & nuclear lamina

  • not all cells have _

Nucleus

When DNA is wrapped into a bundle with eight histone proteins

Nucleosome

• double membrane with two phospholipid bilayers that have pores to allow molecules to enter and exit the nucleus

• eukaryotic nucleus is contained within _

Nuclear envelope

provides mechanical support to maintain the shape of the nucleus

Nuclear lamina

site of ribosome synthesis in an animal cell

Nucleolus

• movement of substances through the nuclear membrane is facilitated by _

• transport mRNA and some proteins out of the nucleus

Nuclear pores

• Site of protein synthesis

• NOT membrane-bound

• found in BOTH eukaryotes & prokaryotes

• made up of ribosomal subunits, which are comprised of rRNA (ribosomal RNA) and proteins

• NOT surrounded by a membrane

Ribosome

Eukaryotic ribosome (60S + 40S).

80S ribosome

Prokaryotic ribosome (50S + 30S).

70S ribosome

• ER with ribosomes; modifies and exports proteins

• synthesizes proteins

• assembles glycoprotein

Rough ER

Synthesizes lipids/steroids, detoxifies, and stores ions.

Smooth ER

• Stack of cisternae

• packaging and transporting substances in vesicles

• does NOT create proteins

Gogli apparatus

Receives vesicles from ER.

Cis face

Sends vesicles away.

Trans face

• Organelle with acidic enzymes for digestion and recycling.

• made by Golgi

• functions

  • apoptosis

  • autophagy

  • break down nutrients, pathogens & cell debris

Lysosome

Breakdown of cell’s own components.

Autophagy

Programmed cell death.

Apoptosis

Storage organelle (transport, food, central, contractile).

Vacuole

Membrane surrounding central vacuole in plants.

Tonoplast

Network for protein/lipid modification & transport (includes nucleus, ER, Golgi, lysosomes, vacuoles, and membrane).

Endomembrane system

• Breaks down fatty acids and toxins;

• forms hydrogen peroxide neutralized by catalase

• common in liver and kidney cells

Peroxisome

Enzyme converting H₂O₂ → H₂O + O₂.

Catalase

• site of ATP production

• Fatty acid catabolism

Mitochondria

• Site of photosynthesis in plants/protists.

• double membraned

• contain their own DNA that is separate from the rest of the cell

• divide by BINARY FISSION

Chloroplast

Two perpendicularly arranged centrioles are known as

Centrosome

• Network providing structure, movement, and transport.

• move components w/in cell

• cell motility

• maintains cell shape

• anchors membrane proteins

• components:

  • microfilaments

  • intermediate filaments

  • microtubules

Cytoskeleton

• class of cytoskeletal filaments, smallest in diameter

• Actin is the protein that makes up _

• important for muscle contraction, cellular motility, vesicle transport, cell junctions, and cytokinesis

• responsible for the cleavage furrow of mitosis

Microfilaments

Medium thickness; mainly keratin; provide durable support and form nuclear lamina.

Intermediate filaments

• Thickest fibers; hollow tubes of tubulin for shape, transport, and chromosome movement.

• makes up the railroad-like network that allows motor proteins to transport cellular components within the cell

• Cilia and flagella are made up of

• ex) centrosomes, MTOCs

Microtubules

motor protein that transports organelles and vesicles from the periphery to center of a cell

Dynein

center to periphery

Kinesin

• form spindle apparatus during cell division

• include centrosome & basal body

• found @ base of each flagellum & cillium

• NO bacterial cells

MTOC (Microtubule Organizing Center)

• Microtubule organizing centers that form the spindle fibers during cell division

• are the MTOCs found in animal cells

• non-membrane bound organelle

Centrioles

• can be found at the base of a cell’s flagellum

• Derived from centriole; anchors cilia/flagella.

• 9×3 microtubule arrangement

• 9 triplet w/ no central pair of microtubules

Basal body

short hair like extensions from cell for movement

Cilia

Protein matrix around centrioles where microtubules form.

Pericentriolar material

• Network outside cell for structural and biochemical support.

• found in BTWN animal cells that hold them tgt & helps them communicate

• made up of: collagen, glycoproteins, integrin, fibronectin

Extracellular matrix (ECM)

cushioning, hydration

Proteoglycan (ECM)

• strength

• MOST abundant proteins in the extracellular matrix

• strong bc triple helix structure

Collagen

• directly anchors components of the extracellular matrix to the plasma membrane

• membrane proteins that connect cell → ECM

Integrin (ECM)

link cells to ECM

Fibronectin (ECM)

ECM protein in basal lamina similar to fibronectin.

Laminin

Rigid support layer in plants, fungi, bacteria, and archaea.

Cell wall

• dense outer coating made up of a slime layer of capsule (carbohydrates)

• shield that protects, sticks & alerts immune system

• Maintenance of blood vessels walls

• present outside of some animal cell membranes and bacterial cell walls

Glycocalyx

• Connect ECM to cytoskeleton

• 2 main types

Cell-maxtrix Junctions

Junction connecting ECM to keratin filaments.

Hemidesmosome Junction

• produces a seal to prevent the movement of molecules between neighboring cells

• kind of junction is found in places such as the digestive/urogenital tracts

• protect the body from toxins, foreign invaders like bacteria, and the breakdown of concertation gradients

Tight Junction

• Anchoring junction using keratin; strong mechanical support.

• Stronger than Adheren Junction

Desmosome Junction

Attaches cells to adjacent cells, forming thick bands that allow for organization into tissues

Adherens Junction

• provides tunnels that allow the movement of small molecules or ions

• used to conduct electrical signals in cardiac muscle cells

Gap Junction

Relative solute concentration across membranes affecting water movement.

Tonicity

• Equal solute concentration inside and outside; no net water movement.

• plants: flaccid

Isotonic

• solute concentration outside of the cell is higher than the concentration inside of the cell

• water exits cell (shrinks).

• plants: Plasmolysis

Hypertonic

• lower solute concentration than the solute concentration in the cell

• water enters cell (swells).

• plants: turgid

• lysis

Hypotonic

circular movement of the cytoplasm around cell transport molecule

Cyclosis

• life’s fundamental units of structure & function

• smallest unit or organization that can perform all activities required for life

cell

• organism composed of 1 or more cells

• cell is basic unit of structure & organization in organisms

• all cells come from preexisting cells

tenets of cell theory

• activity of organism depends on tot. activity of independent cells

• energy flow occurs w/in cells

• cells carry & pass on hereditary info

• all cells have similar basic chem composition among similar species

modern interpretation cell theory

• animal cell membrane

• Regulates membrane fluidity

cholesterol

• functional analogues of cholesterol

• plant

sterol

cell membrane components constantly shifting around

fluid

highly condensed chromatin in the eukaryotic cell

chromosome

general packaging of DNA & proteins

chromatin

aids in organizing DNA into chromatin

histone

60S+40S=80S

eukaryotes

50S+30S=70S

prokaryotes

move material btwn organelles

transport (vacuole)

transports food & fuses w/ lysosomes

food (vacuole)