cell unit test

a group of organelles and molecules working together; fundamental unit of life

cell

two categories of cell

prokaryotes, eukaryotes

maintains water balance; allows organisms to control their internal solute composition/water potential

osmoregulation

diffusion of water across a semipermeable membrane from high to low water concentration

osmosis

water moving into the cell means the solution is ___

hypotonic

no net water movement means the solution is ___

isotonic

water moving out of the cell means the solution is ___

hypertonic

describe how much solute is dissolved in the solvent

tonicity

animal cells are ___ and plant cells are ___ in hypertonic tonicity

shriveled, plasmolyzed

animal cells are ___ and plant cells are ___ in hypotonic tonicity

lysed, turgid

why is turgid good for plants

plant cells have turgor pressure; even if water continues to flow in, the cell membrane pushes against the cell wall, causing turgor pressure; this makes the cell stay firm and stable, and plant cells love to be firm

best tonicity for plant cells

hypotonic

best tonicity for animal cells

isotonic

animal cells are ___ and plant cells are ___ in isotonic tonicity

normal, flaccid

water moves from ___ to ___ water potential

high, low

water moves from ___ to ___ concentration of water

high, low

water moves from ___ to ___ concentration of solute

low, high

water moves from ___ to ___ osmolarity

low, high

water is stored in ___ in plants

large vacuole

the pressure the water exerts back on the cell wall

turgor pressure

(plant cells) water has to move through

cell wall and cell membrane

cells take in molecules into the intracellular space; require ATP energy

endocytosis

the state in which net movement is zero by matching rates of water moving in and out of the cell

dynamic equilibrium

measures the tendency of water to leave one place in favor of another

water potential

net movement of molecules that require a channel protein to occur

facilitated diffusion

two forms of active transport

endocytosis, exocytosis

cells take in molecules into the extracellular space; require ATP energy

exocytosis

water potential is affected by the addition of

solutes and physical pressure

equation of water potential

water potential = pressure potential (0) + solute potential

equation of solute potential

solute potential = -iCRT

net movement of molecules with the concentration gradient; does not require ATP energy

passive transport

net movement of molecules against the concentration gradient; requires ATP energy

active transport

net movement of small, nonpolar molecules without aid of protein

diffusion

high surface area

more places for materials to enter/exit

why do cells need a large surface area to volume ratio?

to be efficient at transport

projections (like villi) will ___ the surface area to volume ratio

increase

cells with projections will be ___ efficient at transporting materials compared to other cell shapes

more

cells have to be big enough to ___

fit all the dna and molecules

cells have to be small enough to ___

efficiently exchange nutrients, oxygen, and waste with extracellular environments to maintain homeostasis

requires formation of a vesicle for bulk export of substances (endocytosis/exocytosis)

exocytosis

requires formation for bulk import of substances (endocytosis/exocytosis)

endocytosis

separation of charge across the membrane

membrane potential

examples of facilitated transport

facilitated diffusion, active transport

___ molecules require the facilitation of channel proteins

large, polar, and charged

examples of passive transport

diffusion, facilitated diffusion, osmosis

The difference in concentration of molecules across a space

concentration gradient

importance of cell transport

transport waste out, absorption of nutrients, oxygen in for respiration, maintain homeostasis

membrane only lets small, non-polar molecules diffuse freely through the spaces between the phospholipids

selective permeability

how do integral proteins stay embedded within membrane?

nonpolar amino acids; anchors protein into membrane

how do integral proteins stay embedded on outer surfaces of membrane?

polar amino acids; extend into extracellular fluid and cytosol

transmembrane proteins with a channel through the middle; used for transport of large, polar, or charged molecules

channel proteins

transmembrane or peripheral proteins that do not have a channel through the middle; used for cell-signaling (ligands bind to the receptor and cause cell to respond)

receptor proteins

functions of cell membrane proteins

transporter, enzyme activity, cell surface receptor, cell surface identity marker, cell adhesion, attachment to cytoskeleton

regulates membrane fluidity in response to temperature changes

cholesterol

carbohydrates attached to phospholipids; facilitate cell-to-cell adhesion and recognition

glycolipids

carbohydrates attached to phospholipid proteins; allow cross linking of cells, which give tissues strength

glycoproteins

membrane without cholesterol

(cold-no flexibility, may break) (hot-too flexible, won’t hold shape)

responsible for controlling what enters and exits the cell; lipid membrane; mainly composed of phospholipids

cell membrane

site of ribosome synthesis in the cell

nucleolus

entire region between the nucleus and the cell membrane; consists of cytosol

cytoskeleton

contains nucleolus and chromatin; site of transcription (DNA transcribed into mRNA)

nucleus

consists of DNA and protein; condenses to form chromosomes

chromatin

double membrane that forms boundary between nuclear contents and cytoplasm; perforated with pores; surrounds nucleus

nuclear envelope

site of protein synthesis (suspended in the cytosol; produces protein for use within cell)

ribosomes (free)

site of protein synthesis (attached to the outside surface of ER; produces proteins for use outside cell or for cell membrane)

ribosomes (bound)

synthesizes lipids/hormones; detoxification of cell waste; doesn’t have attached ribosomes

smooth er

flattened membranous sacs; receives transport vesicles from ER; modifies ER products;

produces lysosomes and secretory vesicles

golgi apparatus

channels proteins to transport vesicles; attaches carbohydrate to some proteins;

involved in membrane production through production of vesicles; has attached ribosomes

rough er

carries ER products to golgi apparatus

transport vesicle

carries golgi apparatus products to cell membrane; fuses with cell membrane releasing contents outside the cell

secretory vesicle

membrane found sac of hydrolytic enzymes; enzymes used to digest food

lysosomes

membrane bound sacs; larger than vesicles; stores materials

vacuole

site of cellular respiration; produces ATP from sugars, fats, etc.

mitochondria

site of photosynthesis; produce food using light energy, CO2 and H2O

choloroplast

contains enzymes that transfer H from substrates to oxygen producing H2O2; detoxifies alcohol

peroxisome

paired structures found in animal cells; involved in cell division

centrioles

maintain the shape of animal cells; help vesicles get transported

cytoskeleton

as cells get bigger, its volume increases ___ than its surface area

faster

smaller objects have a ___ ratio of surface area to volume

greater

cell theory

all living things are made up, fundamental unit, comes from preexisting cells

endosymbiotic theory

eukaryotes evolved from prokaryotes

usually folded to increase surface area

organelle membranes

more specialization =

more complex life

organelles that do not have their own membrane inside of cell

non-membrane bound organelles (ribosomes, cell membrane, cell wall, cytoplasm)

organelles that have their own membrane inside of cell

membrane bound organelles (nucleus, vacuole, mitochondria, choloplast, golgi apparatus, er)

bacteria/archaea; single celled; no nucleus; no membrane bound organelles; older; smaller/simpler

prokaryotes

plants/animals/fungi/protists; single or multi cell; nucleus; membrane bound organelles; larger/complex; evolved;

eukaryotes

in ___, cell takes in macromolecules and particulate matter by forming new vesicles derived from the plasma membrane

endocytosis

cell engulfs solid material; fuses with lysosome for digestion

phagocytosis

cell engulfs dissolved particles; non-specific process

pinocytosis

triggered by molecular signal

receptor-mediated endocytosis

three types of endocytosis

phagocytosis, pinocytosis, receptor-mediated endocytosis