Cell organelles and membranes - AP BIO

Prokaryotic cells

• simpler (no membrane-bound organelles)

• smaller BACTERIAL CELLS

• NO nucleus but a nucleoid region

• plasmids → extra material in small circular DNA pieces

Eukaryotic cells

• more complex (lots of membrane-bound organelles)

• larger and HAVE a nuclues

• plant-like (photoautotrophic) and animal-like (chemoheterotrophic)

• animals, plants, fingis, and protists are composed of eukaryotic

all cells

• contain genetic material, ribosomes, cytosol, and a plasma membrane

Ribosomes

• function in protein synthesis

• are found in pro and euk aryotic cells

• made of proteins and ribosomal RNA (rRNA)

• during translation → assemble amino acids into polypeptide chains

Free ribosomes

• floating in cytoplasm

• make proteins that stay in the cytoplasm

Bound ribosomes

• attached to endoplasmic recticulum

• make proteins that go into membranes or are exported from the cell

Endoplasmic recticulum

• membrane channels in eukaryotic cells

• rough: ribosomes bound to its membrane and function in protein synthesis (close to nucleus)

• smooth: has no ribosomes and functions in synthesis of lipids and detoxification of harmful substances to the cell (far from nucleus)

Golgi complex

• found in eukaryotic

• series of flattened membrane sacs (cisterna) that function in synthesis, modification, and packaging of molecules

• cis face= receiving side that accepts transport vessicles

• trans face= shipping side that sends molecules to final place

• proteins made on free ribosomes/rough ER are sent to the golgi which modifies them into final state and packages them into vesicles for transport through the cell

Lysosomes

• found in eukaryotic

• membrane-bound sacs that function in many cell processes

• can help digest macromolecules, break down worn-out cell parts, function in apoptosis, or destroy bacterial viruses that enter the cell

vacuole

• membrane-bound sac in eukaryotic cells that function in food/water storage, water regulation in a cell, or waste storage

• occupy majority volume in plants, providing turgor pressure and support

mitochondria

• eukaryotic

• produce energy for the cell, double membrane allows ATP production

• have double membranes

• smooth outer membrane, folded inner membrane (increase surface area)

• center: the matrix (enzyme containing fluid)

• contain their own mitochondrial DNA (mtDNA) and own ribosomes

chloroplasts

• eukaryotic

• found in plants/algae that carry out photosynthesis

• double membrane, smooth outer and pancake-shaped membranous sacs called thylakoids that are stacked into structures called grana

• liquid in chloroplast surrounding grana is called stroma

• contian own cholorplast DNA and own ribosomes

centrosome

• found in animal cells and helps microtubules assemble into fibres needed or cell division

amyloplasts

• excess glucose produced by photosynthesis stores as starch molecules in amyloplasts

peroxisome

• oxidize molecules and break down toxins in cells

nucleolus

• not membrane-bound, the region in the nucleus where ribosomes produces RNA are assembled

cytoskeleton

• gives cells shape and moves items into cell

endomembrane system

• together, the nuclear membrane, endoplasmic reticulum, golgi, lysosomes, vacuoles, transport vesicles, and plasma membrane are part of the EMS

• functions: modify, package, and transport polysaccharides, lipids, an dproteins to their final destinations within the cell or prepare them for transport out of the cell

transport vessicles

• small, membrane-bound sacs that move molecules, such as proteins and lipids, between different locations inside a cell

endosymbiosis hypothesis

• membrane-bound organelles (mitochondria and chloroplasts) were once free living prokaryotes that were absorbed into larger prokaryotes

• smaller ones that were engulfed evolved to become membrane-bound organelles

• why? → they both have their own circular DNA (similar to prokaryotic DNA), they have their own ribosomes (similar to pro structure), and are similar to how bacteria reproduce (pro).

simple diffusion

• movement of molecules from an area of high concentration to low concentration

• tiny molecules

• no ATP required, moves through phospholipid bilayer

• O2, CO2, lipids, nonpolar

facilitated diffusion

• high concentration to low concentration

• small/medium molecules

• no ATP but requires proteins to help move through bilayer

• glucose, amino acids, sodium

osmosis

• movement of water through a semipermeable membrane (allows some molecules to pass through but not others) from a place with lots of water to a place with less water

• low solute to high solute

• no ATP required

plasma membrane

• a flexible, protective barrier that surrounds every living cell and separates its inside contents from the outside environment

active transport

• move against gradient

• area of low concentration to high concentration

• requires ATP

exocytosis

• movement of huge macromolecules by wrapping them in vesicles that fuse with the plasma membrane

• proteins, insulin, starch

phospholipid bilayer

• a double layer of lipid molecules that forms a protective barrier for all cell membranes

• hydrophilic heads (face outward)

• hydrophobic tails (face inward)

• selective permeability: lets small, nonpolar molecules pass through easily while blocking large or charged ions