Unit 2: Cell Structure and Function Flashcards
prokaryotic cell
a type of cell that has no organelles
eukaryotic cell
has organelles
cell wall
rigid sturcture outside plasma membrane in plants
plasma membrane
membrane enclosing the cytoplasm
bacterial chromosome
single stand of DNA enclosed by cell membrane
nucleoid
region where prokaryotic cell’s DNA is located
cytoplasm
fluid interior of cell
Why are cells so small?
To maximize their surface area to volume ratio. SA proportional to a^2 and V proportianal to a^3, so SA/V proportianal to 1/a. Smaller cells have a smaller a so a larger SA/V ratio. This allows more diffusion of substances through cell membranes
Nuclear envelope
double membrane that encloses the nucleus and seperates it from the cytoplasm
nuclear lamina
protein filaments that maintain the shape of the nuclear envelope and connects the two layers of the nuclear envelope
nuclear matrix
fibers in the nucleus that keeps its shape
Chromosomes
single structure of a long DNA strand and associated proteins
chromatin
complex of histone proteins and DNA
nucleoli
condensed regions of the nucleus where ribosomes are made
ribosomes
structures of large and small subunits that build and assemble proteins from mRNA
free ribosomes
ribosomes in the cytosol that make proteins that function in the cytoplasm
bound ribosomes
ribosomes in the endoplasmic reticulum or the nuclear envelope that makes proteins for membranes or secretion
What structures make up the endomembrane system?
Nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vesicles, vacuoles, and plasma membrane
endoplasmic reticulum (ER)
membrane network emerging from the nuclear membrane
lumen
space inside cisterna of the rough ER
cisterna
“sac” of the rough ER
transport vesicles
membrane sacs that transport contents to other places in the cell
rough ER
has bound ribosomes; folds proteins for secretion and is a membrane factory for the cell
smooth ER
does not have bound ribosomes on it; synthesizes lipids, metabolized carbohydrates, and detoxifies drugs and poisons
Golgi apparatus
“post-office” for proteins; modifies incoming proteins and sends them out for final functioning
lysosome
membrane sac that has enzymes to break down macromolecules; breaks down particles from phagocytosis and autophagy
phagocytosis
cells “eating” or engulfing outside molecules
autophagy
breaking down damaged cell parts to be recycled later
vacuole
stores stuff like food or water for later use
food vacuole
store macromolecules from phagocytosis to later be used by the cell
contractile vacuole
pumps excess water out of the cell
central vacuole (plants)
stores nutrients like potassium and chloride, absorbs water to keep the shape of the plant cell, and helps with the growth of plant cell
endosymbiont theory
states that an early ancestor of mitochondria or chloroplast was engulfed by a larger cell, and both the smaller and larger cells became symbionts and benefitted. The smaller cell became mitochondria and chloroplast today
mitochondria
energy-producing organelle in the cell that makes ATP from cellular respiration
What are the parts of the mitochondria?
outer membrane intermembrane space inner membrane mitochondrial matrix cristae
chloroplast
energy-producing organelle in plants that makes glucose from sunlight via photosynthesis
What are the parts of the chloroplast?
outer membrane inner membrane space inner membrane stroma granum thylakoids
peroxisomes
remove H atoms from certain substances like alcohol to O2 to make H2O2 which is converted to H2O. This is useful in the liver to detoxify alcohol
cytoskeleton
network of fibers throughout the cytoplasm
What does the cytoplasm do?
Supports and maintains the shape of the cell
Helps move the cell
Manipulates plasma membrane to form vesicles and vacuoles
What are the three main types of fibers in the cytoskeleton?
Microtubules
Intermediate filaments
Microfilaments
microtubules
long hollow rods made of the protein tubulin;
role in cell shape and motility of structures
intermediate filaments
fibers bigger than microfilaments but smaller than microtubules;
they make up the nuclear lamina and help structure the cell and fix position of organelles
microfilaments
fibers made of a double chain of actin filaments;
involved in movement
centrosome
region containing two centrioles involved in assembling microtubules in the cell and in cell division
cilia
structures made of mucrotubules and occur in large numbers and have beating patterns
flagella
“tail” allowing some prokaryotes to move made of microtubules and are limited to only a few. Have wave-like patterns
motor proteins
proteins that “walk” in the cilia or flagella to bend it to cause movement or beating patterns; include dynein and myosin
What is th cell wall made of?
microfibrils made of cellulose as well as other polysaccharides and proteins
primary cell wall
thin and flexible wall secreted first by the plant cell in early life
middle lamella
a layer of sticky polysaccharides called pectins between primary cell walls of adjacent cells
secondary cell wall
extra layer of protection that is hard and durable and is built once the plant cell is fully grown
extracellular matrix (ECM)
fibers outside animal cells for protection and structure
What are the intercellular junctions between plant cells?
plasmodesmata; water and small solutes can pass through them
What are the intercellular junctions in animal cells?
tight junctions: prevent fluid from moving between two cells
desmosomes: fasten cells together into sheets
gap junctions: channels between cells that allow solutes to pass between them
amphipathic
one side of the phospholipid is hydrophilic while the other is hydrophobic
fluid mosaic model
the cell membrane is a mosaic of proteins moving through a dynamic bilayer of phospholipids
membrane fluidity
the cell membrane and the proteins in it are constantly moving
How does decreasing temperature affect membrane fluidity
phospholipids pack together tightly
How does cholesterol control membrane fluidity?
at high temperatures, it keeps phospholipids together
at low temperatures, it keeps phospholipids apart
integral proteins
penetrates completely or partially hydrophobic interior of membrane
peripheral proteins
loosely bound to surface of membrane
What are the functions of membrane proteins?
Transport: protein channels allow certain substances through
Enzymatic activity: can metabolize reactants at the cell membrane
Attachment to cytoskeleton and ECM: maintains the structure of the cell and allows intra and extracellular communication
Cell-cell recognition: glycoproteins are “Tags” to be recognized by other cells
Intercellular joining: proteins of different cells and hookup to communicate
Signal transduction: can relay signals to the cell
glycolipids
carbohydrates bonded to lipids
glycoproteins
carbohydrates bonded to proteins
channel proteins
hydrophilic channel that lets ions pas through
carrier proteins
change shape and shuttle particles through the membrane
aquaporins
channel proteins that allow water through the cell membrane
diffusion
movement of particles from high to low density regions
concentration gradient
a region where the concentration of a substance varies
passive transport
transport not requiring energy
osmosis
diffusion of water across an selectively permeable membrane
isotonic
the environment has the same solute:water concentration as the cell
hypertonic
the environment has a greater solute to water concentration that the cell
hypotonic
the environment has a less solute to water concentration than the cell
turgid
healthy, fully expanded state of plant cell that limits uptake of water
flaccid
wilted state of plant cell
plasmolysis
plant’s plasma membrane wilts so much that cell will die
facilitated diffusion
passive transport of particles vis help of transport proteins
active transport
diffusion of particles against the concentration gradient via transport proteins that require ATP
Sodium Potassium pump
3 Na+ ions out, 2 K+ ions in
membrane potential
voltage (separation of opposite charges) across a membrane
cotransport
when a cotransporter protein shuttles a substance down its concentration gradient, but at the same time shuttles another substance against its concentration gradient
