CH 2: Cells

cells

the smallest living units in our bodies

basic cellular functions

obtain and use nutrients

dispose waste

replicate/regenerate/repair

plasma membrane, cytoplasm, nucleus

main structural components of cells

functions of plasma membrane

protective barrier

cellular communications

regulates movement of substances in and out

fluid mosaic model

plasma membrane structure

not a fixed structure; lots of small components

phospholipids

amphipathic

dynamic arrangement

primary type of lipid

cholesterol

somewhat polar/nonpolar

mostly with tail portion

glycolipid

least prevalent

exterior bilayer with attached sugar chain

for attachment + cellular recognition

integral proteins

embedded in 1 or more layers

peripheral proteins

not embedded in membrane

more easily detached (mobile)

more common on intracellular side

selective permeable

oxygen + CO2 can move across easily

glucose cannot go across

integral proteins

act as transporters and channel to assist in the entrance of impermeant molecules

carrier integral proteins

passive mover (doesn’t require energy)

pump integral proteins

active move (requires energy)

simple diffusion

move directly through bilayer down concentration gradient

lipid soluble + small enough to bypass lipid tails

osmosis

diffuse through aquapore (protein)

facilitated diffusion

integral protein spans membrane and enables passage of solute across membrane down concentration gradient

active transport

use ATP to pump substances across membrane in a preferred direction

vesicle membrane transport

wrapping up in plasma membrane to make a vesicle

active process

phagocytosis, pinocytosis, receptor-mediated

types of endocytosis

phagocytosis

cellular eating

large substances reach out for individual vesicle

pinocytosis

cellular drinking

form pool on cell with extracellular fluid

receptor-mediated endocytosis

triggered by extracellular molecule binding to membrane receptors

signals vesicle forming

cytosol, organelles, inclusions

3 components of cytoplasm

cytosol

jelly-like fluid where all intracellular elements are suspended

made of water, ions, enzymes

site of many chemical reactions

organelles

specialized structures within a cell that have characteristic shapes and perform specific functions

membrane or non-membrane bound

inclusions

temporary structures (for storage)

pigments, crystals of proteins, food stores

ribosomes

functions in protein synthesis

made of proteins + ribosomal RNA

have small + large subunit

endoplasmic reticulum

network of membrane-enclosed cavities (flattened sacs or tubules)

rough er

protein synthesis

has protein ports

cisterns/cisternae

smooth er

making or breaking down fats

calcium storage

no protein ports

golgi apparatus

package, further process proteins

cis face = same side of rough ER (receiving)

trans face = opposite side of ER (shipping)

lysosome

degradation of substances

cellular digestion

peroxisomes

small in size for detoxification

break down free radicals

mitochondria

create cellular energy

double membrane

outer = bilayer

inner = many folds (cristae and matrix = intermembrane space)

cytoskeleton

elaborate network of rods running through cytoplasm

supports cell shape and produces movements

microfilaments

smallest in diameter

highest concentration

in periphery of cytoplasm

easily + regularly broken down

core structure of microvilli

intermediate filaments

2nd smallest in diameter

strongest cytoskeleton

not easily broken down

ex. keratin, myosin

microtubules

largest in diameter

easily + regularly broken down

tube-shaped

form structure of cilia + flagella

nucleus

double membrane nuclear envelope

cell control center

DNA directs activity by providing protein synthesis instructions

nuceolus

dense mass of specialized protein

produces ribosomes

nuclear envelope

2 parallel membranes

outer- continuous with rough ER + has ribosomes

inner- lined by protein filaments to maintain shape

nuclear pores

to get things into nucleus (mRNA)