exam 2 (lecture slides) Flashcards
unfinished- only went up to the 3rd chapter of the unit (cell membrane)
what are transport vesicles
helps move materials, especially proteins from one organelle to another
- distributed by the rough er
what is the endoplasmic reticulum + the 2 types
- cell’s “highway”
- membrane of interconnected tubules that carry stuff around the cell
two types:
rough ER: synthesis and packaging of proteins
- bumpy because ribosomes are attached to it
smooth ER: has enzymes that help create and package lipids and also detoxifying substances
what are centrosomes + centrioles
kinda look like pasta, organize microtubules out of proteins
- in animal cells, centrosome has a pair of centrioles, each with 9 triplets of microtubules arranged in a ring
plants don’t have centrioles, only centrosomes
selective permeability in the cell membrane
chooses what goes in and out
what is the cytoplasm
solution of water and nutrients that fills the cell
what is the cytoskeleton
inside the cytoplasm- bunch of protein strands that reinforce the cell
what is nucleoplasm
nucleus has its own cytoplasm (premium luxury environment)
cis and trans Golgi apparatus
cis: means same
- part of the Golgi apparatus nearest to ER (endoplasmic reticulum), functions primarily in receiving and sorting molecules
trans: means opposite
- part of Golgi farthest from ER, functions in final modifications of proteins before they’re shipped out`
what is the function of the Golgi apparatus?
“post office of cell city”
- processes proteins + packages them before sending them where they need to go
what are Golgi bodies and how is their function different from the Golgi apparatus?
- stacks of membranous layers within the Golgi apparatus (Golgi apparatus layers)
- often used interchangeably though
cut up large proteins into smaller hormones and combine proteins and carbs to make various molecules
what are lysosomes?
sacs of enzymes that break down cellular waste and debris from outside cell to turn into simpler components for inside cell
what are vesicles
sacs that little goodies are packaged into
- used to ship stuff within cell or outside cell
what is autophagy?
lysosomes use enzymes to recycle the cell’s own organelles and macromolecules
what are vacuoles and the 3 different types of them
“diverse maintenance compartments” - storage cells that perform variety of functions
food vacuoles: formed by phagocytosis (when cell engulfs another cell), help digest and break down ingested food
contractile vacuoles: found in freshwater protists, help maintain internal water balance by pumping excess water out of cell
central vacuoles: large ones found in many mature plant cells, store water and nutrients, provide structural support + other functions
what is the function of the mitochondria?
cellular respiration!
- use oxygen to generate ATP
- cells that need more power (such as muscle cells) have more mitochondria in them
what is the inheritance pattern for mitochondria?
maternal b/c mitochondria self replicates so DNA never mixes with the father’s
what is unique about mitochondria compared to other organelles?
acts like its own cell, does its own replication and even has some DNA
function of the chloroplasts
also energy!!
- sites of photosynthesis
- found in plants and algae
3 similarities between mitochondria and chloroplasts
- enveloped by a double membrane
- contain free ribosomes and circular DNA molecules
- grow and reproduce somewhat independently in cells
endosymbiont theory
idea that some organelles inside eukaryotic cells (like mitochondria and chloroplasts) were once independent, free-living bacteria
- bacteria engulfed by larger cells, instead of being digested, formed mutually beneficial relationship with the host cell
what are cristae
folds in the inner membrane of a mitochondria
- present a large surface area for enzymes to synthesize ATP
what are chloroplasts known for
site of photosynthesis
- contain green pigment chlorophyll
3 things plants contain that animal cells don’t
- cell wall
- plastids
- large vacuole
purpose of the large vacuole in plant cells
used for storage but also:
pushes water to create turgor pressure so cell stays nice and rigid
what are plastids? (difference from chloroplasts)
group of plant organelles (such as chloroplasts) in cytoplasm of plant cell that contain pigment or food
most important type of plastid: chloroplast
2 main parts of a chloroplast
thylakoids: membranous sacs that capture light to turn into ATP solar panels of the cell
- stack to form granum
stroma: internal fluid that contains enzymes to use chemical energy to produce sugar kitchen of the cell, uses products to assemble
do plant cells have mitochondria?
yes, they have both mitochondria and chloroplast (chloroplasts are used for photosynthesis only)
how are mitochondria and chloroplasts similar?
- both have double-membrane
- have their own DNA and manufacture ribosomes
- grow and divide independently of cell division
- energy producing organelles
photosynthesis (chloroplasts) vs. cellular respiration (mitochondria)
- photosynthesis builds glucose by capturing energy from the sun and stores the glucose for later use
- cellular respiration breaks down glucose to ATP and for use within the cell
peroxisomes
“clean-up crew”
- responsible for breaking down toxic substances, primarily hydrogen peroxide
- destroys alcohol by removing hydrogen atoms
cytoskeleton
network of fibers that organizes structures & activities in the cell
- cell mobility usually requires interaction with of the cytoskeleton w/ motor proteins
3 components:
- microtubules
- microfilaments
- intermediate filaments
motor proteins
specialized proteins that move along the cytoskeleton, carrying cellular cargo, such as organelles, molecules, or other components, to specific locations within the cell
THEY MOVERSSS
microtubules
“highways of the cell”
- thickest of the 3
- long, tube-like structures made of protein that serve as tracks or roads for motor proteins to move along (organelle movements)
- maintain cell shape, help with cell motility (like in cilia and flagella)
- aid in chromosome movements in cell division
found in all eukaryotic cells
cilia and flagella
microtubule containing extensions that project from some cells
cilia: present in lung + throat cells to push up mucus
flagella: present in sperm cells
protozoans move around using cilia and flagella
dynein
motor protein which drives the bending movements of a cilium or flagella
- known for moving cellular structures and cargo along microtubules
HAS THEM 2 FEET AND IT WALKS
microfilaments
- thinnest of the 3, thin solid rods built from molecules of actin (also a globular protein)
- helps support shape, cell motility, cell shape, and cell division, muscle contractions and changes in cell shape
found in all eukaryotic cells
intermediate filaments
- size is between microtubules and microfilaments
- tension-bearing elements, can take mechanical stress, important for tissues that need to be strong and resilient
- *not found in ALL eukaryotic cells,
myosin
protein that plays crucial role in muscle contraction
- microfilaments that function in cellular motility contain the protein myosin in addition to actin
pseudopodia
“cellular arms” or “temporary extensions” that some cells use to move and capture prey
- usually in single-celled organisms like amoeba
cytoplasmic streaming
“cellular traffic flow”
- movement of cell’s cytoplasm and the materials within it in a coordinated manner to distribute essential substances within the cell
- driven by actin protein interactions
3 layers of plant cell walls
primary cell wall: relatively thin and flexible, secreted first
middle lamella: thin layer b/w primary walls, containing polysaccharides called pectins
secondary cell wall: (in some cells), added b/w plasma membrane and primary cell wall
ECM of animal cells
- animal cells lack cell walls but are covered in extracellular matrix
- made of glycoproteins such as collagen, proteoglycans, and fibronectin
integrins
“cellular velcro”
- proteins on the surface of cells that help stick to and interact with environment
tight junctions, gap junctions, and desmosomes (anchoring junctions)
tight junctions: “cellular zippers,” connect neighboring tissues tightly to make sure there are no leaks
- ex. present in digestive tract
gap junctions: “communication tunnels,” allow quick communication through openings that allow molecules and ions to pass directly
- ex. present in heart cells
desmosomes: fasten cells together into strong sheets, important in tissues subjected to mechanical stress, like skin and heart muscles
meaning of amphipathic molecule and its relation to membrane structure
amphipathic: containing hydrophobic and hydrophilic regions
- cell membrane is composed of lipids and proteins, specifically phospholipids which keep the structure intact
fluid mosaic model
used to refer to the membrane structure as it is a mosaic of proteins molecules bobbing in the fluid bilayer of phospholipids
- proteins are not randomly distributed, they are in groups that carry out common functions
- not rigid in the way you would think a cell wall is, can move laterally, packed less and more tightly in some cases
factors that affect membrane fluidity (3 factors + give reasons for why)
- membranes with more unsaturated fatty acids are more fluid (because of the kinks, they cannot pack together as closely)
- as temperature cools, becomes less fluid and more solid
- cholesterol molecules embedded in membrane - reduce fluidity but prevent total tight packing (helps because when you reduce temperature, membrane won’t solidify as quickly)
membranes must be fluid to work properly
membranes are held together by ___________________ bonds
weak hydrophobic
phospholipids form main fabric of membrane, but ________ determine most of membrane’s functions
proteins
- protein composition of membranes varies among cells within an organism, and among intracellular membranes within a cell
2 types of membrane proteins
integral proteins: penetrate hydrophobic interior of phospholipid bilayer, some extend partway some completely
- majority are transmembrane proteins: span the entire membrane
peripheral proteins: not embedded in the bilayer at all, but loosely bounded to the top, often exposed partially
what are the 6 major functions of membrane proteins?
- transport: transmembrane proteins can help facilitate movement of molecules
- enzymatic activity: membrane proteins can serve as enzymes where they would attach to the active site
- signal transduction: membrane protein might have the specific shape needed to bind and relay the message to inside the cell
- cell-cell recognition: some glycoproteins serve as identification tags that are recognized by membrane proteins of that cell
- intercellular joining: can hook together to form many types of junctions, like gap or tight junctions
- attach to cytoskeleton or ECM: microfilaments can be noncovalently bonded to membrane proteins to help maintain cell shape and stabilize location of certain cells
how does the polarity of a molecule affect its crossing of the cell membrane?
- nonpolar molecules are hydrophobic and have easy time passing through
- polar molecules are hydrophilic and have difficulty passing (get stuck) or pass really slowly (including water)
proteins that are built into the membrane can help certain things pass
transport proteins + the 2 types
help move various substances such as ions and molecules across the membrane
channel proteins: have a hydrophilic channel that certain molecules or ions can use as a tunnel
- ex. aquaporins: little channels that allow water to enter
carrier proteins: bind to molecules and change shape to shuttle them across membrane
- transport proteins are specific to the substance they move (so glucose carrier proteins only move glucose)
passive transport vs. active transport
passive transport: diffusion of substance across membrane with no energy required, goes down concentration gradient (high to low)
active transport: requires energy to move substances, movement against concentration gradient (low to high)
- if 2 substances in a solute, moves down its OWN concentration gradient, not the overall concentration gradient
2 things that the selective permeability of a membrane is dependent on
- natural permeability of a lipid bilayer (i.e. polar and nonpolar)
- specific transport proteins built into the membrane
osmosis
diffusion but basically only for water
- high to low water concentration
- low to high solute concentration
tonicity
ability of a solution surrounding a cell to cause that cell to gain or lose water
- hypo, hyper, and iso (but you already know this)
what is plasmolysis
when plants are placed in a hypertonic environment, they lose water and cell shrivels
- membrane pulls away from cell wall = plant wilts and dies
preferrable condition: turgid
what is osmoregulation
control of solute concentration and water balance
- important for organisms that live in very hypo or hypertonic environments
facilitated diffusion
speeds transport of solute by providing efficient passageway to go through
still passive bc doesn’t go against the concentration gradient
- ex. channel proteins
sodium-potassium pump
- example of active transport
- exchanges sodium for potassium against the electrochemical gradient
- pumps sodium ions out and potassium ions in
membrane potential
- all cells have voltages (electric potential energy, separation of opposite charges)
- inside cell is more negative compared to the outside of the cell
- pumps regulate this by pumping ions using energy
affects the movement of ions
electrogenic pump
active transport proteins that generate voltage across membrane while pumping ions
- in animals: Na/K pump
- in plants, fungi, bacteria: proton pump (actively transports hydrogen ions (H+) out of cell
bulk transport + 2 types + 3 types of endocytosis
- large molecules, like polysaccharides and proteins, need to cross inside vesicles CAUSE THEY FAT
exocytosis: vesicles transport materials outside of the cell
- ex. nerve cells releasing neurotransmitters
endocytosis: vesicles transport into the cell
- two types: phagocytosis and pinocytosis
phagocytosis: devouring action, engulfs invader and then destroys
pinocytosis: drinking action, cell membrane folds and creates little pocket to bring things in (for fluids and other small substances)
receptor-mediated endocytosis: vesicle formation is triggered by solute binding to receptors, allows cell to acquire bulk quantities of specific substances
first and second law of thermodynamics
first law of thermodynamics: conservation of energy, energy of the universe is constant, energy can be transferred and transformed, but cannot be created or destroyed
second law of thermodynamics: during every energy transfer, some energy is converted to thermal energy and lost as heat
- every energy transfer or transformation increases entropy (molecular disorder, randomness) of the universe
catabolic vs. anabolic pathways
catabolic pathways: release energy by breaking down complex molecules into simpler ones
- ex. cellular respiration (break down of glucose in the presence of oxygen)
anabolic pathways: consume energy to build complex molecules from simpler ones
- ex. synthesis of proteins from amino acids
what is bioenergetics
study of how energy flows through living organisms
what is metabolism
totality of an organism’s chemical reactions, consisting of anabolic and catabolic pathways
energy definition
capacity to cause change
what does metabolic pathway mean
series of chemical steps that occur inside cell to transform one molecule into another
- each step is catalyzed by a specific enzyme, a macromolecule that speeds up a specific reaction
kinetic energy, potential energy, thermal energy, and chemical energy
kinetic energy: energy associated with motion
- ex. water gushing through a dam turns turbines
potential energy: energy stored ready for action, has to do with position or structure
- ex. book on shelf can fall and do work or stretched rubber band
- molecules possess energy due to the arrangement of electrons in bonds between their atoms
thermal energy: associated with heat, the more heat something has = more thermal energy
chemical energy: energy stored in bonds b/w molecules
- ex. potential energy stored in food
what is thermodynamics
study of energy transformations in a collection of matter
isolated vs. open system
isolated: doesn’t exchange energy or matter with surroundings, “closed box” - ex. liquid in a thermos bottle
open: able to exchange both energy and matter with surroundings
- organisms are open systems, exchange light or food and release heat
how to tell if a reaction occurs spontaneously or not?
- by the free energy change
spontaneous: reaction will proceed without an input of energy
*negative ∆G = reaction will be spontaneous
positive ∆G = reaction is NOT spontaneous*
enthalpy
∆H
- measure of the total heat content of a system
- positive = heat is absorbed
- negative = heat is released
entropy
∆S
- measure of disorder in a system (represents dispersion of energy)
- disordered state = high entropy state
Gibbs free energy + equation
describes the amount of work that can be done in a system given the thermodynamic environment
∆G = ∆H - T∆S
*temperature in Kelvin
when G is positive = endergonic reaction
when G is negative = exergonic reaction
exergonic vs endergonic reactions
- exergonic: energy out, more energy released than absorbed (∆G is negative)
- endergonic: energy in, more energy absorbed than released (∆G is positive)
what is equilibrium
point at which forward and reverse reactions occur at the same rate
- state of maximum stability
what is energy coupling
energy released by one reaction is used to drive another reaction
- mostly mediated by ATP in cells
structure and hydrolysis of ATP
composed of: ribose (a sugar), adenine (nitrogenous base), and 3 phosphate groups
- ATP stores a lot of energy in it and is broken down by hydrolysis
- the water and ATP molecule combine releasing a lot of energy, turning ATP into ADP
- cell “unzipping” ATP when it needs the energy
phosphorylation and phosphorylated intermediate
phosphorylation: transfer of a phosphate group from ATP to another molecule, this transfer is used to modify or activate the target molecule
- common way for cells to control and regulate various processes, such as signaling and enzymatic reactions
phosphorylated intermediate: the molecule with the phosphate tag
ATP cycle
- ATP can regenerate (turns into ADP but can be turned back into ATP)
- energy from catabolism (exergonic, energy-releasing processes) is used to synthesize ATP
- energy released by ATP hydrolysis is used for cellular work (endergonic, energy-consuming processes)
enzyme, catalyst, & substrate
enzyme: macromolecule (protein) that acts as a catalyst to speed up a specific reaction (limited to biological reactions and are specific to the one reaction that they carry out)
catalyst: chemical agent that speeds up a reaction without being consumed by the reaction (are not usually specific to a certain reaction, also not limited to biological reactions)
substrate: reactant that an enzyme acts on
activation energy
free energy of activation
“energy hurdle” that a chemical reaction must overcome to get started
- initial energy needed to break the bonds of reactants
- acts like a barrier that determines the rate of spontaneous reactions
catalysis
process by which a catalyst selectively speeds up a reaction without being consumed itself by lowering the activation energy
enzyme-substrate complex & active site
“lock and key”
when enzyme binds to its substrate, allowing enzyme to carry out its work
active site: region on enzyme that binds to substrate
induced fit (in regards to enzyme-substrate)
enzyme changes shape slightly to fit the substrate
- kinda like how you change grip on hand to shake someone else’s hand
rate of an enzyme-catalyzed reaction is increased by increasing ____________
substrate concentration
- at some point substrate concentration is high enough that all enzyme molecules have their active sites engaged = substrate concentration is saturated
noncompetitive (allosteric) vs. competitive inhibitors
competitive inhibitors: “molecular rivals” that are competing with the substrate to bind to the active site
- increasing substrate concentration can overcome inhibition
- blocks substrate = reduces enzyme productivity
noncompetitive inhibitors: “molecular blockers” that bind to a different site on the enzyme, changing its shape to make it less effective at catalyzing reaction
- ex. toxins, antibiotics, pesticides
allosteric regulation (activator and inhibitor)
- “remote control” - controls from a distance, molecule binds elsewhere and changes function and shape of protein
allosteric activator: “protein cheerleader,” encourages the protein’s activity
allosteric inhibitor: when binds, slows down or blocks protein activity
cooperatively in enzyme-substrate complexes
one substrate molecule binds to an enzyme, and this binding makes it easier for additional substrate molecules to bind to other active sites on the same enzyme
feedback inhibition
“brake system” for controlling a process
- when product accumulates to a specific level, “feeds back” to inhibit or slow down earlier step in the process
fermentation
partial degradation of sugars that occurs without oxygen
- used when cells need energy but theres not enough oxygen available
