Unit 2 - Cell Structure and Function Flashcards
types of cells
- prokaryotes
- eukaryotes
prokaryotes
- made up of bacteria
- archaea extremophile (an organism that thrives under extreme conditions)
eukaryotes
- mammals
- plants
- fungi
- protists
prokaryote’s organelles
- no membrane bound organelles
prokaryote’s DNA
- free floating DNA
- DNA is circular shaped
- DNA is found in nucleoid
- contains plasmids (extra circular pieces of DNA)
prokaryote’s cell wall
- cell wall is made up of peptidoglycan
eukaryote’s organelles
- has membrane bound organelles
- contains mitochondria
eukaryote’s DNA
- DNA found in nucleus
- DNA is linear shaped
eukaryote’s cell wall
- plant cell wall -> cellulose
- fungi cell wall -> chitin
common structures between eukaryotes and prokaryotes
- ribosomes - rRNA
- cell (plasma) membrane
- cytoplasm - cytosol
cytosol
the actual liquid portion of the cell
nucleus
- DNA is found inside here
- surrounded by a nuclear membrane
- “pores” to allow things in and out
endoplasmic reticulum
- function: intracellular transport
- rough ER
- smooth ER
rough endoplasmic reticulum
- ribosomes are found here
- ribosomes produce proteins for cell membrane / for outside cell
- intracellular transport
smooth endoplasmic reticulum
- intracellular transport
- synthesis of lipids
- steroids (estrogen & testosterone)
- detoxification
- abundant in liver to breakdown toxins and drugs
ribosomes
- synthesize proteins
- found free floating / attached to rough ER
- made up of rRNA (make proteins for membrane/outside cell)
- free floating: makes proteins for inside the cell
golgi apparatus
- finalize proteins to be exported to the cell membrane or out of the cell
- “tertiary structure”
- produces vesicles for transport **
- produces lysosomes
- cisternae
endomembrane system
- nucleus produces mRNA to go to the ribosomes on the ER
- the rough ER makes proteins then sends them to golgi to be exocytose (leave cell)
lysosome
- hydrolysis: digesting using enzymes and water
- apoptosis: programmed cell death (recycling of cellular material)
- autophagy: digestion of worn out cell parts
- immune cells (like a giant lysosome)
mitochondria
- cell respiration: makes ATP
- endosymbiotic theory: a cell engulfed a mitochondria
-> it was not digested
-> it made energy and received glucose - have their own ribosomes, DNA, self replicating
chloroplast
- absorbs sunlight -> makes sugar
- have their own ribosomes, DNA, self replicating
vacuole
- storage: water, food, waste
- tonoplast: membrane around the vacuole
endosymbiotic theory
- the beginning of eukaryotic cells
cytoskeleton
- microtubules
- intermediate filaments
- microfilaments
- cilia
- flagella (whip like tail)
- structural support
peroxisome
- break H2O2 -> H2O + O
centrioles
- involved in cell reproduction
- in animals
advantages of organelles
- eukaryotic cells can grow larger than prokaryotes
- able to compartmentalize
- allows us to carry out lots of metabolic reactions
- more complex organisms
what does the ability to compartmentalize mean
- lots of reactions in separate places
surface area to volume ratio
- the amount of surface area in a given volume
** larger ratio is better
surface area
- sum of the area of all faces of an object
formula for surface area of a cube
6a^2
why is a large surface area to volume a good thing for cells
- most efficient diffusion of nutrients/wastes
ex: CO2, O2
how do cells increase surface area?
- cell membrane has folds
- in blood cells, the dent increases surface area so more O2 diffusion
what are structural adaptations that increase surface area to volume ratio
- plants have root hairs
- increase surface area to absorb nutrients
desert hare structural adaptations
- large ears -> cool rabbit down (thermoregulation)
- long legs -> cool down rabbit
snow shoe hare
- small ears -> less exposure so cold air keeps heat in
- shorter legs -> keeps heat in
cell membrane
- regulates what goes into and out of the cell
- AKA phospholipid bilayer, plasma membrane
- semipermeable
semipermeable
- allows somethings to pass, but not all
how does a cell membrane regulate what goes in and out
- polarity
- head = polar -> hydrophilic
- tails = nonpolar -> hydrophobic
why is the cell membrane called a bilayer
- orientation of the phospholipids
- hydrophobic tails do not want to be near water
fluid mosaic model
- molecules in cell membrane move laterally (side to side) like a fluid
- many molecules in the membrane (mosaic)
what kind of molecules can pass through a nonpolar region with no resistance
- sterols/steroids
- CO2, O2
what kind of molecules cannot pass through a nonpolar region with no resistance
- polar molecules
- charged molecules
- large molecules
cell membrane: cholesterol
- maintains fluidity of cell membrane
cell membrane: integral protein
- transport protein
ex: aquaporin - transport of water
cell membrane: peripheral proteins
- cell signaling
cell membrane: glycoprotein or glycolipid
- cell recognition –> “immune system”
the smaller the cell, the ______ the SA:V ratio
larger
why are all cells pretty much the same size?
- small cells achieve a large surface area to volume ratio so that nutrients and wastes can diffuse efficiently
- there is also less distance for molecules to travel within a small cell so that cellular functions occur more quickly
what are three characteristics that increase SA:V ratio
- small size of the cell
- infoldings of membranes
- organelles
endosymbiosis
- symbiotic relationships within the cell
- theory of how eukaryotes formed
proof of the theory of endosymbiosis
- double membranes of organelles
- mitochondria and chloroplasts have their own DNA
- mitochondria and chloroplasts self replicate
- the ribosomes in mitochondria and chloroplasts are more similar to the ribosomes of prok than euk
in prokaryotic cells, almost all reactions occur on the cell membrane
- which does NOT allow for specialization
- unlike eukaryotic, which has organelles
mitochondria and chloroplasts are no longer self sufficient; they need..
enzymes provided in the cell’s cytoplasm
does DNA leave the nucleus
- no, it sends a copy via RNA
nucleolus/nucleoli
- rRNA is synthesized here
- this RNA makes up ribosomes
bound ribosomes
- bonded to organelles
- synthesize proteins for export (secretion) from the cell or for use in lysosomes
free ribosomes
- floating in the cytoplasms
- synthesize proteins mostly for use within the cell
are ribosomes membrane bound
- no, they are NOT membrane bounded; therefore, they are found in both eukaryotes and prokaryotes
ribosomes carry out
translation (protein synthesis)
purpose of the endomembrane system
- to transport, package, and export proteins destined for use outside that particular cell
autophagy and apoptosis
- involved in the destruction of worn out or unneeded structures
ex:
- destruction of worn out red cells or mitochondria
- disappearance of a tadpole’s tail
contractile vacuoles
- in protists to pump out excess water
central vacuoles
for storage of starch in plant cells
peroxisome
- single membrane
- breaks down fatty acids
- detoxes alcohol in liver
- as the break down compounds, they produce H2O2
membrane fluidity
- as fluid as salad oil
- the only thing holding the cell membrane together is the fact that the interior and exterior are exposed to water
how does the membrane remain fluid and resist freezing?
- amount of unsaturated fatty acids (these have kinks that prevent molecules from packing together)
- amount of cholesterol
simple diffusion
- the passive movement of particles from higher to lower concentration
- when a hydrophobic (nonpolar) molecule passes between the molecules of the lipid bilayer
- no energy is needed
how does water get across the cell membrane
facilitated diffusion (no energy)
- protein channels allow for the exchange of polar molecules
aquaporin
- the protein channel that allows water to pass across the cell membrane via facilitated diffusion
larger molecules (proteins, carbs) are carried across membrane how
by transport proteins via active transport which includes carrier proteins
passive transport
- movement down a concentration gradient
- no ATP needed
- diffusion of small, nonpolar molecules via simple diffusion
- diffusion of polar substances through channels via facilitated diffusion
transportation of large molecules
- exocytosis
- endocytosis
- protein pumps
what do all cells need to live?
- all cells need nutrients
ex: O2, Na+, K+ - need to remove wastes
ex: CO2
permeable
allows substances to enter or exit the cell
concentration gradient
amount of molecules on one side of a membrane vs the other
osmosis
diffusion of H2O
- passive transport
what are proteins used for in facilitated diffusion
to move larger or charged molecules across a membrane
- ex: integral protein
is facilitated diffusion passive or active transport
passive transport
active transport
- energy is used
- ATP or electron gradient
- moving from low [ ] to high [ ]
ex: “pump”, permeases
Na+/K+ pump
3 Na+ leave and 2 K+ enter the cell
- active transport
endocytosis
bringing in larger molecules
- 2 Types: pinocytosis, phagocytosis
pinocytosis
cell drinking
(type of endocytosis)
phagocytosis
cell eating
(type of endocytosis)
exocytosis
releasing larger molecules
tonicity
- waters ability to move to solutions with higher solute concentration
isotonic
- the solute concentration is equal in and out of the cell
- no NET movement of water
hypotonic
- more water in solution, less solute
- causes cell to burst/lyse
plant cells in hypotonic solution
- they will not burst due to cell wall
- they will become turgid: H2O pushing on the wall
animal cells in hypotonic solution
- cytolysis
water flows towards what type of solution
hypertonic solution
hypertonic
- more solute, less H2O in solution
hypertonic solution: plant cells
- cell membrane gets plasmolyzed (shrinks)
hypertonic solution: animal cells
- crenation (shrivels up)
water flow in terms of concentration of solute
water flows from areas of low concentration of solutes to high concentration of solute
osmoregulation
- management of the body’s water and solute concentration
- conformer vs regulator
paramecium
- freshwater invertebrate
- contractile vacuoles
- uses ATP
- H+ pumped into vacuole
- results in hypertonic cell
- H2O flows in
- H2O gets pumped out
most marine (salt) invertebrates are
isotonic to their environment - conformers
freshwater organisms must be
regulators
freshwater fish osmoregulation
- actively transport ions (Na+) into their gills
- urine: dilute + a lot
saltwater fish osmoregulation
- actively transport ions (Na+) out of them through gills
- urine: concentrated, little
humans osmoregulation
- ADH
- creates aquaporins in the kidneys
- allows for water to be reabsorbed by body
water potential
- a measure of how likely water will move from one solution to another
what are two variables that affect osmosis and the movement of water?
- pressure
- amount of solute (NaCl, sugar)
pressure potential
- a physical force
** in an open container, pressure = 0 (no added pressure)
solute potential
- amount of solute in a solution
- reason H2O moves to high solute concentration because it is attracted to it
what is the solute potential of distilled water
- 0
- this is the highest value bc it contains NO SOLUTE
- adding solutes decreases solute potential
total water potential in a plant cell
- plant cells have a cell wall that exerts pressure
solute potential formula
-iCRT
solute potential: i
ionization constant
- how many molecules does it dissociate into in water
solute potential: C
- molar concentration
- usually given to you
solute potential: R
- pressure constant
- 0.0831 bars
solute potential: T
- temperature in kelvin
what type of water potential does water flow towards
- water flows towards the hypertonic, which means towards the more negative water potential
transpiration: water potential
- the decrease in water potential as you move up has more to do with the pressure than the solute concentration
- water will flow from higher water potential to lower water potential, and therefore move up from the roots to the leaves to the atmosphere
prokaryotes
- single celled organisms that lack a nucleus and other membrane bound organelles
prokaryotes reproduce how
asexually through binary fission, simpler process than eukaryotic cell division
what is meant by membrane bound organelles
- each of these organelles is enclosed by its own membrane
- this allows the organelles to maintain a controlled internal environment that is distinct from the rest of the cell
- membrane regulates what enters and exits the organelle
nucleoid in prokaryotes
a region in the cytoplasm where the cell’s genetic material (DNA) is located, DNA is free floating in the cell
nucleus is enclosed by
nuclear envelope: double membrane
- outer membrane is continuous with ER which allows for communication and material exchange between these structures
nucleus: chromatin
- DNA combines with proteins to form this; then, it’s shaped into chromosomes
nucleolus
dense, spherical structure; site of rRNA rsynthesis and assembly of ribosomes
rRNA
ribosomal RNA
how does the nucleus control cellular activities
by directing protein synthesis
nucleus: transcription
- DNA is transcribed into mRNA which then exits through the nuclear pores and travels to ribosomes to become proteins
endoplasmic reticulum
a network of membranes that plays a key role in the transport, production, and processing of proteins and lipids
what is continuous with the nuclear envelope
rough endoplasmic reticulum
what proteins do rough ER ribosomes synthesize
- those that will be secreted from the cell or incorporated into the cell membrane
rough ER: post protein synthesis
- proteins are packaged into vesicles and sent to golgi for further processing and distribution
smooth ER: lipid synthesis
- includes phospholipids and steroids (ex: cholesterol)
smooth ER: detoxification
- in liver cells, smooth ER contains enzymes that detox harmful substances
smooth ER: calcium storage
- in muscle cells, smooth ER stores Ca+2 ions that are essential for muscle contraction
ribosomes: function
- site of protein synthesis
- translate genetic info into mRNA into proteins
are ribosomes found in prokaryotic or eukaryotic cells?
both!
ribosomes: protein synthesis
ribosomes do the translation; ribosomes read mRNA sequence and translate into chain of amino acids
free floating ribosomes
- float freely in the cytoplasm
- synthesizes proteins for function within the cytoplasm / nucleus / mitochondria
prokaryotic + eukaryotic ribosomes: antibiotics
- antibiotics fighting bacterial infections often work by interfering with the prokaryotic ribosomes, which differ enough from eukaryotic ribosomes that the drugs don’t harm human cells
golgi apparatus consists of
series of folded membrane bound sacs called cisternae
cisternae
folded membrane bound sacs
golgi apparatus: cis face
- side closest to the rough ER; receives the newly synthesized proteins and lipids from the ER
golgi apparatus: trans face
- side oriented towards plasma membrane; responsible for exporting processed materials to their final destination
golgi apparatus: functions
- synthesizes lysosomes
- as proteins pass through, several modifications occur that can affect tertiary structure (adding carbohydrate or phosphate groups can affect folding and function)
golgi apparatus: folding assistance
- chaperone proteins ensure that proteins achieve their correct tertiary structures
golgi apparatus: vesicle formation
- when the membrane bends inwards and pinches off to create small sacs that carry proteins and lipids
- these isolate substances without interfering with other cellular activities
endomembrane system
complex system of membranes within eukaryotic cells that carries out synthesis, transport, modification and degradation of proteins and lipids
what does the endomembrane system include
nucleus, ER, golgi apparatus, vesicles, lysosomes
endomembrane system: nucleus
- holds DNA and controls cellular activities; mRNA
endomembrane system: E.R.
rough -> protein synthesis
smooth -> lipid synthesis
endomembrane system: golgi apparatus
- modifies and packages proteins and lipids for transport
endomembrane system: vesicles
small sacs that carry materials between organelles or to the cell membrane for secretion
endomembrane system: lysosomes
- break down waste and recycle materials
endomembrane system: exocytosed
vesicles fuse with the cell membrane and expel contents to outside the cell
lysosomes
specialized organelles that break down wastes or cellular debris
lysosomes: structure
- surrounded by a membrane that isolates its contents from the rest of the cell
- contains hydrolytic enzymes, powerful proteins, that can break down different types of macromolecules
what do lysosomes digest
they digest both incoming substances (bacteria) & worn out organelles (autophagy)
lysosomes: immune cells
in immune cells, lysosomes help destroy pathogens that are engulfed by the cell
apoptosis
programmed cell death
mitochondria: structure
- double membrane; inner is folded into structures called cristae which increase surface area for energy production
cristae
the inner membrane folds of mitochondria
- increases surface area
mitochondrial matrix
the space inside the inner membrane where metabolic reactions occur
mitochondria: endosymbiotic theory
- they have their own ribosomes and DNA
- allows them to produce some proteins they need without the help of nucleus
- proof for endosymbiotic theory
advantages of organelles: compartmentalize
allows functions to happen in separate places without interference
advantages of organelles: growth
eukaryotic cells can grow larger than prokaryotic cells
cytoskeleton
structural support
endosymbiotic theory suggests
- that the first eukaryotic cell emerged from a prokaryote
endosymbiotic theory
prokaryote (bacteria) swallowed smaller bacteria that were capable of making energy (mitochondria/chloroplasts)
- instead of digesting, they formed a partnership as the bacteria provided energy for the cell
- overtime, the bacteria became a permanent part of the cell and transformed into first eukaryotic cell
benefits of high surface area to volume ratio
- faster diffusion: more efficient exchange of gases
- less distance for transport
- cell signaling: high surface area allows for more receptors on the cell membrane
how do plants increase surface area
they have root hairs
