Flashcards in cell test Deck (34):
What is an organelle?
specialized subunits of cells that have a particular function
prokaryotes have a few
eukaryotes have many, usually surrounded by a membrane
this where we get the term "membrane-bound organelles"
WHAT is the function of the ell membrane?
also called plasma membrane
protects and supports the cell
controls what enters and leaves the cell
it is a lipid bilayer (2 LAYERS OF FAT CELLS)
found in all types of cells- prokaryotes and eukaryotes
What is the function of the cell wall? (plants)
found in eukaryotic plant and protist cells; also in prokaryotes
main function is protection, rigidity, and support
outside of cell membrane
made of cellulose (A CARB)
allows water and dissolved substances to pass through
What is the function of the nucleus?
controls most activities in the cell
usually one per cell
contains DNA the coded instructions for making proteins and other molecules for the cell
the nuclear envelope has nuclear pores,, where things can enter or leave
What is the function of the nucleolus?
small, dense region in the middle of the nucleus
this is where ribosomes are formed
What is the function of the cytoplasm?
clear fluid within cell that contains all organelles
moves materials throughout the cell
What is the function of the ribosomes?
makes proteins in the cell
may be free in cytoplasm or attached to ER
proteins are vital to life-all cells must produce them
What is the function of the Golgi apparatus (body)?
stacks of membranes used for storing, modifying, or packaging chemicals
packaged chemicals can be stored inside the cell or secreted outside the cell
cells that make saliva or mucus have many Golgi bodies
What is the function of the endoplasmic reticulum? (ER)?
series of folded membranes that form sacs or tubes
two types- smooth and rough
What is the difference between the rough and smooth endoplasmic reticulum?
ribosomes make it look rough or bumpy
ribosomes synthesize ( make ) proteins, so the rough ER is where this happens
smooth- no ribosomes
synthesizes (makes) lipids
What is the function of lysosomes?
made by the Golgi apparatus
full of digestive enzymes to digest unwanted particles
help white blood cells to destroy bacteria
What is the function of peroxisomes?
filled with enzymes to digest toxic substances
numerous in the liver
do not form at Golgi body
what is the function of vacuoles?
store food, water, or waste materials
in plant cells they are very large
What is the function of chloroplasts?
found in eukaryotic plant cells and some protist cells
capture light energy and convert it into chemical energy during photosynthesis
What is the function of the mitochondria?
energy producers- the "powerhouse" of the cell
convert chemical energy into useable energy
found in animal and plant cells
What is the function of the cytoskeleton?
overlapping network of filaments and fibers that support the cell and help it maintain its shape
can also help cells move microfilaments and microtubules
What is the function of centrioles?
help to organize the cell during cell division
they migrate to either side of the cell and help to pull it apart
only found in animal cells
What is the function of the flagellum?
extension of the cytoskeleton- allows movement, main source of transportation for cells
only some animals and some prokaryotes have these
What is the function of cilia and pili?
extension of the cytoskeleton- allows things to move around the cell.
propels mucus in your throat, helps with hearing in your ears, and helps move food particles in your stomach
only some animal cells and some prokaryotes
Which organelles have their own set of DNA?
only two organelles have their own DNA- mitochondria and chloroplasts
among multicellular animals, nearly all of the mtDNA in a fertilized egg is inherited from only the mother
one mechanism for this is simple dilution: an egg contains 100,000 to 1,000,000 mitochondria , whereas a sperm contains only 10 to 100
What is the evolutionary origin of mitochondria and chloroplasts?
mitochondria and chloroplasts descended] from ancient prokaryotes that developed symbiotic relationships with ancient cells
in other words... mitochondria and chloroplasts are former prokaryotes that now "live" inside eukaryotes
WHat is the fluid mosaic model?
the cell membrane is NOt a rigid structure with immovable components!
the cell membrane is fluid-like and flexible
within the membrane, molecules can move around
What is the Phospholipid bilayer?
LIPIDS: Phospholipids made up the majority of the cell membrane
hydrophilic head made of phosphates (phospho)
hydrophobic tail made out of fatty acids (lipid)
to protect the hydrophobic tails from water,they form a bilayer which keeps the tails huddled inside and the water loving heads outside
What is a solution?
molecules dissolved in a liquid= SOLUTES
Liquid/fluid dissolving them= SOLVENT
There two together make a SOLUTION
What are concentration and equilibrium?
solutions will spread out their dissolved molecules until they are equal throughout
EQUILIBRIUM = molecules are spread equally
CONCENTRATION= number of molecules in an area per unit volume
HIGH CONCENTRATION: more solutes per unit volume
LOW CONCENTRATION: less solutes per unit volume
What happens with a barrier?
if the solutions on either side of the barrier have the same concentration we call thatbeing at equillibrium
at equilibrium, both the solvent and solute move bak and forth acros the barrier: there is ALWAYS MOVEMENT
transport of materials across the cell barrier
materials move across the plasma
membrane in two ways:
passive transport- movement cross the membrane without using energy
active transport- movement across membrane that requires energy
solutes move across a membrane from areas of high concentration (crowded) to low concentration
because diffusion depends upon random particle movements, diffusion across cell membranes does not require the celll to use energy
diffusion of water
water molecules (fast and small) pass through the cell's selectively permeable membrane
the solute molecule is too large to pass- only the water diffuses until equilibrium is reched
large molecules or those with a charge need the help of a protein to pass across a cell membrane
proteins form a channel and molecules move through the " doorway"
each channel is specific to a particular type of molecule
doesn't require energy
some movement across a cell membrane requires energy because it is AGainst the concentration ( it moves solutes from low to high concentration- where it's already crowded)
when there is a difference in solution concentrations we say that there is a concentration gradient
a special type of protein is used to PUSH molecules to across the membrane
a pocket (vacuole) forms around a large molecule outside the cell and buds inward to release the material inside the cell