Unit 2: Cell Structure and Function Flashcards
Cell Theory and “Fitness”
- all living organisms are composed of one or more cells
- the cell is the basic unit of structure + function in an organism
- all cells come from preexisting cells
“Fitness” organisms’ ability to survive and reproduce
Prokaryotes vs Eukaryotes
PROKARYOTE:
-no membrane bound organelles
- simpler (building block to more complex organisms)
- free floating DNA and ribosomes
EUKARYOTES:
- MEBRANE BOUND ORGANELLES
- typically multicellular organisms but not always
- DNA in nucleus
Nucleus
command center of the cell, turns DNA into mRNA to be used in the cell
Endoplasmic reticulum
largest part of the endomembrane system
Ribosome
made of rRNA and proteins
the site of protein synthesis (translation)
free floating: makes proteins for internal use
bound (rough ER): makes proteins for external use aka secretory proteins
Golgi Body/Apparatus
the shipping center of the cell and site of post translation protein modifications
- also produces vesicles
structure: series of membrane bound sacs + layers that process and transport form the RER
Chloroplasts
site of photosynthesis (light into chemical energy)
- follows endosymbiotic theory b/c of the double membrane, chloroplast DNA, and ribosomes
only in autotrophic eukaryotes
structure:
thylakoids - internal structures + membrane (where light reaction happens)
stroma: outside of thylakoids
lumen: inside of thylakoids
concentration gradient = high in lumen low in stroma
mitochondria
site of cellular respiration in ALL eukaryotes (produces the ATP for the cell)
follows endosymbiotic theory b/c of double membrane, ribosomes, and mitochondrial DNA
structure:
matrix - inner structure made by crista (the inner membrane folds and layers)
cell res happens in cytoplasm, matric, and inner membrane
Concentration gradient = low in matrix high in intermembrane space
lysosomes
used for breaking down waste, pathogens, cell debris, and recycling materials
- has hydrolytic (digestive) enzymes inside that break this stuff down
- used for apoptosis (cell suicide)
vacuole
- used as storage for food, water, and waste
- large in plants but small in animals
-also contains hydrolytic enzymes to digest certain materials
cell membrane
made of a phospholipid bilayer (polar heads + nonpolar tails) so anything large, charged, or polar can’t enter without help
- only small non-polar molecules can enter without help (steroids, oxygen, and CO2)
- has other molecules (proteins and carbs) embedded into it that are always moving = FLUID MOSIAC MODEL
Functions:
1. boundary of cell b/t environment + other cells
2. site of communications with universe through receptors
3. SELECTIVE PERMIABILITY - control what enters and exits the cell
Cell Wall
rigid + tough structure outside cell membrane
- provides shape + supports for plants and fungi (made of cellulose)
cytoskeleton
network of proteins that provide support and structure to cell
- also transport route (cell highway) for vesicles + materials
made of actin, microtubules, and intermediate filaments
centriole
ONLY IN ANIMALS
- major player in mitosis + meiosis b/c they organize microtubules + spindle fibers for cell division
- their location dictates other organelle location
Flagella/ Cillia
Flagella: whiplike structure that helps some prokaryotes swim (like a tail)
Cillia: hairlike structure in prokaryotes and eukaryotes that allows swimming and movement of materials along external surface of cell (ex. removing dust from respiratory tract)
Path of secretary proteins
- DNA translated to mRNA in nucleus
- mRNA goes to ribosome in RER and is translated to a protein
- protein taken to golgi body to be modified and packaged
- protein is taken to the cell membrane
- protein is secreted out through the membrane
Concentration Gradient
difference in concentration of a solute on different sides of the membrane
*Moves down concertation gradient = moving to dynamic equilibrium
Passive Transport
when molecules move across membrane WITHOUT using energy (simple diffusion)
- using channels + proteins can still be passive transport if they don’t use energy (facilitated diffusion)
Simple versus Facilitated diffusion
BOTH are passive transport, but simple diffusion goes straight through membrane and facilitated uses protein channels and carriers
Rate of diffusion + its factors
factors:
1. steepness of concentration gradient (high gradient = faster movement)
2. higher temp = faster movement
3. size (smaller molecules = faster movement)
Simple diffusion:
liner relationship, rate increases as time increases b/c infinite amount of solute can pass through membrane
Facilitated diffusion:
logarithmic relationship, rate increases fast as start but reaches max b/c limited number of carriers + channels so limited amount of solute can go through in a period of time
Dynamic Equilibrium
when a solute is at equal concentration on both sides on mem but continues to move back and forth in equal amounts
*Each solute reaches equilibrium on their own
Cell membrane proteins
Peripheral + integral: peripheral are only on one side while integral are on both
transport: always integral, move materials in out of the cell
receptor: sense changes + send signal (signal transduction)
enzymes: allows chemical reactions to occur + lower activation energy (lock + key interactions)
integrins: anchoes that hold the cell in place (connect extracellular region to cytoskeleton)
glycoproteins: sugar attached (tags to know what cells are ours(
cholesterol: stabilizing molecule +maintain flexibility
Aquaporins
specific proteins that ONLY allow movement of water (transport proteins + water channels)
Osmosis
the movement of WATER from high to low concentration
