AP Bio: Unit 2: Cell Structure and Function

Eukaryotic & Prokaryotic

• Contain membrane-bound organelles and are more complex than prokaryotic cells

• Animals, plants, fungi, protists

• DNA is in linear chromosomes contained in nucleus

• Simpler Structure

• Bacteria: sometimes contains extra genetic material in circular pieces called plasmids

• Genetic material is a circular chromosome located in the center of the cell: Nucleoid region

• Function: Protein synthesis

• Animal and Plant Cells

• Made of proteins and rRNA

• Subunits of prokaryotic ribosomes are slightly smaller than eukaryotic

Found in cytosol of eukaryotes and prokaryotes

Only in eukaryotes on Rough ER

• Series of membrane challenges

Ribosomes bound to membrane and function in protein synthesis

Function in synthesis of lipids and detoxification of harmful substances

• Stack of flattened membrane sacs (cisternae)

• Function: Controls modification and packaging of proteins for transport

• Proteins created by rough ER sent to GB which modifies and packages them for transport

• Membrane-bound sacs containing hydrolytic enzymes

• Function: Digest macromolecules, break down worn-out parts, apoptosis, destroy viruses, bacteria

Function: Food/water storage, water regulation, waste storage

Takes up lot of space, helps in plant cell turgor, structure, and support

Only in plant cells

Function: Carry out photosynthesis

Structure: Double-membrane, contains own DNA

Pancake-shaped membranous sacs stacked

Function in light reactions

Stacks of thylakoid membranes

Liquid in which Grana is surrounded by; functions in light reactions

• Excess glucose from photosynthesis stored as starch here

• Location: roots of starchy vegetables

Function: produce energy

Structure: Double membrane: smooth outer, folded inner (creates proton gradient for ATP production and increase SA for energy production in CR)

Contains own DNA

Center filled with fluid with enzymes

Krebs Cycle occurs here

Function: Helps microtubules assemble into spindle fibers in cell division

Defects: associated with dysregulation of cell cycle in some cancers

Oxidize molecules and break down toxins

Region in nucleus where ribosomes assemble

Fibers that help give shape and move items

How membrane bound organelles originated?

Hypothesis: MB-organelles were free-living prokaryotes that absorbed into larger prokaryotes to become MB-organelles

• Mitochondria and chloroplasts: Each have own circular DNA and ribosomes (both in similar structure to prokaryotic enzymes)

  • Reproduce by binary fission

• MB organelles in eukaryotic cells form specialized compartments that separate enzymes in metabolic processes

  • Minimizes risk of different process enzymes cross-reacting

  • Prok. cells don’t have MB organelles, but fold their plasma membranes to increase surface area

• Allows cells to maintain favorable internal environments

• Selectively permeable

• Fluid mosaic model

• Made of a bilayer of phospholipids

Glycoproteins, modified lipids called glycoproteins, and steroids

Can flow through surface of plasma membrane to change due to environmental changes

cell recognition, cell signaling, chemical reaction catalysis, cell anchoring

cell recognition

Change membrane fluidity to environmental changes

• Oxygen, Nitrogen, and CO2

• Larger molecules need assistance to cross

  • Polar and charged molecules use embedded membrane channels or transport proteins

• Small polar molecules can cross in small quantities

  • Aquaporins: Usually do most of the water passage

• Also called diffusion

• Higher concentration to lower concentration

• Down concentration gradient

• Requires no energy

• Uses membrane proteins to assist moving polar or charge molecules

• Specialized channel proteins: Transport ion like Ca+ or Cl-

• Rate of facilitated diffusion is limited by # of membrane proteins

Diffusion of water

• Requires energy

• Low concentration to High concentration

• Against concentration gradient

Na+ pumped in from lower concentration to higher

K+ pumped out from lower concentrations to higher

Used by cell to take in H2O and macromolecules by enfolding them into the plasma membrane

Used by cell to get rid of waste. Vesicles that contain molecules that need to be expelled fuse with the plasma membrane to allow molecules to be expelled from the cell

• Lower concentration of solute

• Higher water potential

• Higher concentration of solute

• Lower water potential

Same concentration of a solution than another solution

• Potential energy of water in a solution

• Flows from high potential to low potential

Solute potential + pressure potential

Most cases pressure potential=0

i=ionization constant

• how many particles or ions a solute will form in a solution

c=concentration of solute

• as concentration increases, solute potential decreases

R=pressure constant

T= temperature of solution in kelvins (C+273)

Total concentration of solutes in a solution

• In paramecium- excess water entering cell is stored and pumped out the cell