AP Bio Unit 2.1 & 2.4

eukaryotes

• have internal membranes that create specialized organelles

  • compartmentalization → increases efficiency

Prokaryotes

• no membrane-bound organelles

• have regions with specialized structures & functions

  • ribosomes, DNA, cell membrane, cell wall

compartmentalization increasing efficiency

• minimizes competing enzymatic reactions

• increased membrane surface area for reactions that utilize a membrane

ribosomes

• found in all cells

  • evidence for common ancestry of life

ribosomes function

synthesize protein

ribosomes structure

• ribosomal RNA (rRNA)

• protein

• non-membrane

endomembrane system parts

• nuc env

• ER

• golgi

• lysosomes

• transport vesicles

• plasma membrane

endomembrane system

a group of membrane-bound organelles that work together to modify, package and transport polysaccharides lipids & proteins within the cell

ER function

makes proteins & helps the cell maintain shape

ER structure

a network of tubes extending from the nuclear envelope through the cytoplasm

rough ER

helps transport proteins synthesized at tits membrane - bound ribosomes

smooth ER

detoxes cells & synthesizes lipids

golgi complex functions

• correctly folding & modifying new proteins

• packing proteins for export

golgi complex structure

series of flattened membrane sacs

lysosome functions

• break down waste & other materials

• assist in apoptosis

  • programmed cell death

lysosome structure

membrane-enclosed sac that contains hydrolytic enzymes

vacuole function

• animals → store cellular materials

• plants → store h2o & nutrients & helps maintain turgor pressure

vacuole structure

membrane bound sac

• animals → many small

• plants → 1 large

phospholipids

modified lipids with a polar phosphate head & nonpolar fatty acid tails

phospholipid bilayer

hydrophobic tails on inside of bilayer to avoid extracellular/intracellular environment

what is in the phospholipid bilayer

• proteins

• steroids

• glycoproteins

• glycolipids

they can move around within the bilayer

integral proteins

span across the membrane

peripheral proteins

only on one side

steroids

small lipids imbedded in the interior of the membrane effecting its fluidity

cholesterol

steroid found in vertebrates acts as buffer helps membrane maintain constant fluidity at various temps

glycolipids & glycoproteins

• linked to sugars

• typically found only on extracellular surface

• involved in cell 2 cell interactions

cell wall

• structural boundary

• permeability barrier for some substances

• protection from osmotic lysis (cell bursting from 2 much pressure)

• in plants made of cellulose (fiber)

selective permeability

hydrophobic interior of the membrane stops certain molecules from passing through

molecules that can freely pass

small nonpolar

• N₂

• O₂

• CO₂

mols that can pass in small amounts

small polar

• H₂O

• NH₃

cells can use membrane channels to increase mvmt

cannot pass freely

large polar molecules

• glucose

• sucrose

*require channels

Ions

• K⁺

• Cl^-

• Na⁺

• H⁺

*blocked by tails need transport proteins