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BIOL 201
Unit 3
149
Biology
Undergraduate 2
03/28/2017

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Term
lipid bilayer
Definition
The structure of a cellular membrane, in which two layers of phospholipids spontaneously align so that the hydrophilic head groups are exposed to water, while the hydrophobic fatty acid tails are pointed toward the center of the membrane
Term
cell membrane/plasma membrane
Definition
The membrane surrounding the cytoplasm of a cell; consists of a single phospholipid bilayer with embedded proteins
Term
hydrophilic
Definition
Literally translates as “water-loving” and describes substances that are soluble in water. These must be either polar or charged (ions)
Term
hydrophobic
Definition
Literally translates as “water-fearing” and describes nonpolar substances that are not soluble in water. Nonpolar molecules in water associate with each other and form droplets
Term
amphibilic
Definition
having both hydrophobic and hydrophilic regions
Term
fluid mosaic model
Definition
membrane is a fluid structure consisting of a mosaic of different lipids, proteins, and carbohydrates
Term
cholesterol
Definition
affects membrane fluidity by acting as a temperature buffer (decreasing fluidity at high temps and increasing fluidity at low temps) and as a "wedge" to force apart phospholipids at low temperatures
Term
integral protein
Definition
a membrane protein that is permanently attached to the plasma membrane; all transmembrane proteins are integral proteins, but not all integral proteins and transmembrane proteins
Term
peripheral protein
Definition
membrane proteins that adhere only temporarily to the biological membrane with which they are associated
Term
selective permeability
Definition
some substances can cross the membrane more easily than others; allows for compartmentalization
Term
passive transport
Definition
The movement of substances across a cell's membrane without the expenditure of energy
Term
Brownian motion
Definition
random motion of molecules
Term
diffusion
Definition
movement of molecules from an area of high concentration to an area of low concentration; no energy input
Term
concentration gradient
Definition
difference in concentration between a region with a high density of molecules and a region with a low density of molecules
Term
osmosis
Definition
diffusion of water across a selectively permeable membrane; no energy required
Term
tonicity
Definition
the ability of a solution to cause a cell to either gain or lose water
Term
isotonic
Definition
solution inside the cell has the same solute concentration as the solution outside the cell; no net movement
Term
hypotonic
Definition
solution inside cell has a greater solute concentration than solution outside the cell; net movement of water into the cell
Term
hypertonic
Definition
solution inside the cell has a lower solute concentration than solution outside the cell; net movement of water out of the cell
Term
osmoregulation
Definition
ability to control the water balance within a cell
Term
contractile vacuole
Definition
a vacuole in some protozoans that expels excess liquid on contraction
Term
facilitated diffusion
Definition
passive diffusion of molecules, from an area of greater concentration to an area of lower concentration, across a membrane via transport proteins; allows for diffusion of large and/or charged molecules
Term
transport proteins
Definition
involved in the movement of ions, small molecules, or macromolecules, such as another protein, across a biological membrane
Term
channel proteins
Definition
A transmembrane protein with a hydrophilic interior that provides an aqueous channel allowing diffusion of species that cannot cross the membrane
Term
aquaporins
Definition
channel proteins in some types of cells that allow water to move through more quickly than osmosis alone
Term
active transport
Definition
movement of a solute from an area of low concentration to an area of high concentration; requires energy and protein pumps
Term
protein pumps
Definition
"engine" that can utilize energy to move a solute up its concentration gradient
Term
proton pump
Definition
actively transports H+ against their concentration gradient
Term
bulk transport
Definition
transport of large molecules and other objects that require specialized modes of transport; requires huge amounts of energy
Term
exocytosis
Definition
export from the cell; secretion of molecules by fusion of a vesicle with the plasma membrane; secretion is a controlled process
Term
endocytosis
Definition
uptake of molecules and particulates by formation of a new vesicle from the plasma membrane; can be specific or non-specific
Term
phagocytosis
Definition
engulfment of a particle via extensions of pseudopods, resulting in food vacuole formation
Term
secretion
Definition
when a vesicle membrane physically touches the cell membrane and the membranes fuse, releasing vesicle contents to the exterior of the cell
Term
vesicle
Definition
membrane-bound structures inside the cell cytoplasm filled with "stuff"
Term
pseudopods
Definition
A nonpermanent cytoplasmic extension of the cell body
Term
paracrine
Definition
A type of chemical signaling between cells in which the effects are local and short-lived
Term
endocrine
Definition
long-lived chemical signaling that travels through the blood to reach specific target cells
Term
hormone
Definition
A molecule, usually a peptide or steroid, that is produced in one part of an organism and triggers a specific cellular reaction in target tissues and organs some distance away
Term
signal reception
Definition
the target cell detects a signalling molecule present in the exogenous environment
Term
signal transduction
Definition
the conversion of the signal to a form that can bring about a specific cellular response
Term
signal response
Definition
the specific cellular effect brought about by the signalling molecule
Term
ligand
Definition
A signaling molecule that binds to a specific receptor protein, initiating signal transduction in cells
Term
receptor
Definition
A specialized cell or group of nerve endings that responds to sensory stimuli
Term
Describe the importance of phospholipids to the structure of a biological membrane.
Definition
allows for selective permeability and formation of cellular compartments
Term
Why does a membrane need to be fluid?
Definition
to allow for passage of molecules and spontaneous repairs of ruptures or breakage; in case of animal cells, allows for a wide variety of shapes
Term
What are some factors that can influence how fluid a membrane is?
Definition
temperature, ratio of unsaturated:saturated fatty acids, amount of cholesterol
Term
Describe the types of proteins you might find associated with a cellular membrane. Where are they located?
Definition
transporter, enzyme, cell-surface receptor, cell-surface identity marker, cell-to-cell adhesion, cytoskeleton marker; can be found across cell membrane or attached peripherally
Term
Where on a cell membrane would you find carbohydrates? What is one function they serve?
Definition
found only on the extracellular leaflet; function in cell-to-cell recognition
Term
Explain how the structure of a cell membrane functions to selectively inhibit the passage of some molecules while allowing the passage of others.
Definition
only small and hydrophobic molecules can diffuse freely across the cell membrane; larger and/or charged molecules must pass through channel or transport proteins, which may only allow for the passage of certain molecules
Term
Explain the relationship between Brownian motion, diffusion & osmosis.
Definition
diffusion and osmosis are a result of Brownian motion
Term
How does a concentration gradient relate to diffusion and osmosis?
Definition
both diffusion and osmosis only occur DOWN a concentration gradient
Term
How might different tonicities affect an animal cell? A plant cell?
Definition
hypotonic: plant cells become turgid; animal cells lyse
isotonic: plant cells become flaccid; ideal for animal cells
hypertonic: plant cells plasmolyze (wilt); animal cells shrivel
Term
How do different types of cells regulate their internal water concentrations?
Definition
animal cells pump ions out of the cell to create an isotonic environment; protozoan cells pump water out via contractile vacuoles
Term
What is the difference between diffusion & facilitated diffusion?
Definition
diffusion is passive movement across the cell membrane; facilitated diffusion makes use of transport proteins in the cell membrane
Term
What is the difference between passive transport & active transport?
Definition
active transport expends energy while passive transport does not
Term
Provide at least one example each of diffusion, facilitated diffusion and active transport.
Definition
diffusion: oxygen in the lungs diffuses from the alveolar air space into the blood circulating around the lungs
facilitated diffusion: sodium-potassium pump
active transport: proton pump transports H+ against its concentration gradient
Term
How is bulk transport different than diffusion, facilitated diffusion or active transport?
Definition
it requires huge amounts of energy, and utilizes vacuoles and the plasma membrane to move large quantities out of, in to, or within the cell
Term
What types of bulk transport are there? What is the function of each type?
Definition
exocytosis: exports from the cell
endocytosis:uptake of molecules into the cell
phagocytosis: engulfment of a particle
Term
Describe the relationship between bulk transport & membrane fluidity.
Definition
bulk transport relies on the fluidity of the cell membrane either by vesicles fusing with it to release particulates to the extracellular environment, or to form new vesicles from the cell membrane for uptake of particulates into the cell
Term
Provide at least one example of each exocytosis, endocytosis & phagocytosis.
Definition
exocytosis: secretion of insulin from pancreatic cells
endocytosis: uptake of neurotransmitters by post-synaptic neuron
phagocytosis: ingestion of bacteria by white blood cells
Term
Discuss the role/influence of the membrane in regulating signaling events?
Definition
proteins and signaling molecules found on the surface of the cell membrane receive and transmit signals
Term
What must occur to/with signaling molecules in order for a signal to be sent from one cell to another?
Definition
the signal must leave the signaling cell, travel to the target cell, be received by the target cell, and ultimately produce a cellular response
Term
Describe some common cellular responses to signaling events.
Definition
altering the activity of an enzyme(s), rearranging the cytoskeleton, altering transcription of particular genes in a genome
Term
What do animal, plant, and prokaryotic cells have in common?
Definition
DNA, cell membrane, cytoplasm, ribosomes
Term
What are some differences between animal, plant, and prokaryotic cells?
Definition
prokaryotes have small ribosomes and round DNA; eukaryotes have large ribosomes (except on the ER) and linear DNA (except in the mitochondria & chloroplasts)
Term
What do plant & animal cells have in common?
Definition
SER, RER, golgi body, mitochondria, vesicles, cytoskeleton
Term
What are some differences between plant & animal cells?
Definition
plant cells have: cell wall, central vacuole, chloroplasts
animal cells have: flagellua, cilia, centriole
Term
Why is it critical that cells are small?
Definition
the larger the ratio of surface area to volume, the harder it is to move stuff around (diffusion, osmosis)
Term
Where in a cell might you find ribosomes?
Definition
cytoplasm, mitochondria, chloroplasts, rough endoplasmic reticulum
Term
What are the endomembrane system's major functions within a cell?
Definition
modify, package, and transport lipids and proteins
Term
Trace the path a protein might take through the endomembrane system, beginning with protein synthesis and ending with exocytosis from the cell.
Definition
synthesized in rough ER -> transport vesicle -> cis face of the golgi -> through the golgi -> sorted and packaged into vesicles sprouting from trans face of golgi -> other parts of the cell or secretion (exocytosis) from the cell
Term
What role do vesicles play within the endomembrane system?
Definition
transportation and storage
Term
Can all organelles produce vesicles? If not, which organelles can?
Definition
no; the golgi apparatus, endoplasmic reticulum, and cell membrane can produce vesicles
Term
What role do vacuoles play within cells?
Definition
storage and digestion
Term
Are vacuoles found in all cells? If not, which types of cells are they found in?
Definition
no, vacuoles are only found in plant cells
Term
What role to lysosomes play within cells?
Definition
vesicle that contains digestive enzymes
Term
Are lysosomes found in all cells? If not, which types of cells are they found in?
Definition
no, just eukaryotic cells
Term
What is the endosymbiotic theory? Describe the pieces of evidence that support endosymbiotic theory.
Definition
Theory that proposes that eukaryotic cells evolved from a symbiosis between different species of prokaryotes. Evidence includes small ribosomes and circular DNA in mitochondria and chloroplasts
Term
What are they three major components of the cytoskeleton? Compare and contrast the 3 components.
Definition
microtubules, microfilaments, & intermediate filaments; microtubules are everchanging and anchor organelles, microfilaments rearrange to allow for cell movement, and intermediate filaments are strong and rope-like and provide strength and support for the fragile tubuline structures
Term
What is the difference between a stable structure & a dynamic structure?
Definition
stable structure (intermediate filaments) provide support for ever-changing dynamic structures (microtubules & microfilaments)
Term
How is a centriole related to the cytoskeleton?
Definition
centrioles make up centrisomes, which are responsible for organizing microtubules in animal cells (& some protists)
Term
Cell Theory
Definition
1. all organisms are made of cell(s)
2. all cells arise from preexisting cells by division
3. cells are the smallest living things
Term
Surface area:volume
Definition
the larger the ratio of surface area to volume, the harder it is to move stuff around
Term
prokaryote
Definition
a cell lacking a membrane-bounded nucleus or membrane-bounded organelles.
Term
eukaryote
Definition
A cell characterized by membrane-bounded organelles, most notably the nucleus
Term
cytoplasm
Definition
The material within a cell, excluding the nucleus
Term
cytosol
Definition
The fluid portion of the cytoplasm; it contains dissolved organic molecules and ions
Term
cell wall
Definition
The rigid, outermost layer of the cells of plants, some protists, and most bacteria
Term
plasma membrane
Definition
The membrane surrounding the cytoplasm of a cell; consists of a single phospholipid bilayer with embedded proteins
Term
ribosome
Definition
The molecular machine that carries out protein synthesis; prokaryotes have small ribosomes, eukaryotes have large ribosomes (except for mitochondria, chloroplasts, and RER)
Term
organelle
Definition
Specialized part of a cell; literally, a small cytoplasmic organ
Term
nucleus
Definition
holds DNA; surrounded by double layer membrane with pores
Term
nuclear envelope
Definition
The bounding structure of the eukaryotic nucleus. Composed of two phospholipid bilayers with the outer one connected to the endoplasmic reticulum
Term
chromatin
Definition
The complex of DNA and proteins of which eukaryotic chromosomes are composed
Term
nucleolus
Definition
In eukaryotes, the site of rRNA synthesis
Term
endomembrane system
Definition
A system of connected membranous compartments found in eukaryotic cells
Term
rough endoplasmic reticulum
Definition
attached directly to nucleus; covered in ribosomes; makes proteins
Term
smooth endoplasmic reticulum
Definition
further from nucleus; doesn't make proteins; lots of different functions (making lipids, filtering toxins, etc.)
Term
vesicles
Definition
A small intracellular, membrane-bounded sac in which various substances are transported or stored
Term
golgi complex
Definition
not attached to nucleus or cell membrane; "sac" enclosed in its own membrane; "packaging & processing center" of the cell; receives vesicles from RER & sorts contents, then sends contents into cell
Term
lysosome
Definition
produced by golgi; pumps in protons to lower pH & activate enzymes; acts like a "stomach"
Term
vacuole
Definition
A membrane-bounded sac in the cytoplasm of some cells, used for storage or digestion purposes in different kinds of cells; plant cells often contain a large central vacuole that stores water, proteins, and waste materials
Term
mitochondria
Definition
found throughout cell; double membrane; processes sugars & makes ATP; have their own ribosomes & their own circular DNA
Term
chloroplast
Definition
A cell-like organelle present in algae and plants that contains chlorophyll (and usually other pigments) and carries out photosynthesis
Term
leucoplast
Definition
colorless plastids found in endosperm, tubers, roots and other non-photosynthetic tissues of plants; serve various functions such as storage of starch, lipids, or proteins
Term
amyloplast
Definition
A plant organelle called a plastid that specializes in storing starch
Term
cytoskeleton
Definition
A network of protein microfilaments and microtubules within the cytoplasm of a eukaryotic cell that maintains the shape of the cell, anchors its organelles, and is involved in animal cell motility
Term
intermediate filaments
Definition
provides mechanical support for the plasma membrane where it comes into contact with other cells or with the extracellular matrix
Term
actin filaments
Definition
Smallest diameter of the three cytoskeletal elements; involved in cell motility and with myosin part of myofilaments
Term
actin monomer
Definition
G-actin or F-actin; both of which are essential for such important cellular functions as the mobility and contraction of cells during cell division
Term
microtubules
Definition
a long, hollow protein cylinder, composed of the protein tubulin; these influence cell shape, move the chromosomes in cell division, and provide the functional internal structure of cilia and flagella
Term
tubulin
Definition
a long, hollow protein cylinder, composed of the protein tubulin; these influence cell shape, move the chromosomes in cell division, and provide the functional internal structure of cilia and flagella
Term
centriole
Definition
divides and organizes spindle fibers during mitosis and meiosis
Term
centrisome
Definition
microtubule organizing center
Term
What is the first law of thermodynamics?
Definition
energy can be transferred or transformed, but it cannot be created or destroyed
Term
What is the second law of thermodynamics and how does it affect living organisms?
Definition
every energy transfer or transformation increases the disorder of the universe; it takes work (energy) for living things to stay organized
Term
Where is potential energy stored inside cells?
Definition
inside chemical bonds
Term
Why is energy required within cells? What is it used for?
Definition
energy is needed to do work; ATP synthesis, movement, cell division, phagocytosis, any cellular process that needs energy input
Term
Why do some reactions require energy input and others (spontaneous) do not?
Definition
reactions that release energy & decrease order do not need energy input
Term
What’s ATP and what do cells use it for?
Definition
adenosine triphosphate; used for most energy-dependent cellular processes due to its enormous potential energy
Term
[image]
Definition
ATP molecule
Term
What is the relationship between ATP and enzymes?
Definition
ATP powers cellular work, and most cellular work is performed by enzymes
Term
What is an enzyme? Why do cells have so many enzymes?
Definition
an enzyme is a catalytic protein; each enzyme carries out only one specific reaction
Term
How does an enzyme work/how does it do what it does?
Definition
an enzyme speeds up the rate of a chemical reaction; each enzyme has an active site that fits a very specific reactant
Term
What is the relationship between structure and function for an enzyme? How is that related to its active site?
Definition
the structure of the active site determines what reactant can interact with the enzyme
Term
How do changes in temperature affect enzyme function?
Definition
as temperature increases, the rate of the reaction increases, until it reaches its optimum condition and any further heat input denatures the enzyme
Term
How do changes in pH affect enzyme function?
Definition
Changes in pH may not only affect the shape of an enzyme but it may also change the shape or charge properties of the substrate so that either the substrate connot bind to the active site or it cannot undergo catalysis
Term
What is an enzyme inhibitor?
Definition
a molecule that bonds to either the active site or the inhibition site; binding the the active site blocks access for reactants; binding to the inhibition site changes the shape of the enzyme, making it so that reactants cannot bond to the active site
Term
What happens to a cell/organism if its enzyme function is compromised?
Definition
chemical reactions wouldn't happen fast enough and a cell could not maintain homeostasis
Term
catabolic pathway
Definition
break down molecules into smaller molecules & release energy
Term
anabolic pathway
Definition
consume energy to build big molecules from smaller ones
Term
metabolism
Definition
all of the catabolic & anabolic reactions that occur within a cell (or organism)
Term
catabolism
Definition
those metabolic reactions that result in the breakdown of complex molecules into simpler compounds, often with the release of energy
Term
anabolism
Definition
The biosynthetic or constructive part of metabolism; those chemical reactions involved in biosynthesis
Term
potential energy
Definition
could do work or stored energy; not currently moving
Term
kinetic energy
Definition
energy of motion
Term
energy
Definition
capacity to do work
Term
1st law of thermodynamics
Definition
energy cannot be created nor destroyed, it can only be transferred or transformed
Term
2nd law of thermodynamics
Definition
every energy transfer or transformation increases the disorder of the universe
Term
spontaneous reaction
Definition
reaction that doesn't need energy input
Term
adenosine triphosphate
Definition
ATP; responsible for most of the energy available to cells; nucleotide with 3 phosphate groups
Term
enzyme
Definition
catalytic protein
Term
catalyst
Definition
a chemical agent that speeds up a chemical reaction without being consumed or permanently altered by that reaction
Term
activation energy
Definition
the amount of energy reactants must absorb to begin a chemical reaction; prevents many molecules from breaking down spontaneously
Term
substrate
Definition
the reactant acted upon by an enzyme
Term
active site
Definition
region of the enzyme that binds to the substrate
Term
enzyme specificity
Definition
enzymes only act on certain substrates; due to a good fit between the shapes of active site & the substrate(s)
Term
optimum conditions
Definition
environmental conditions at which an enzyme functions its best; will be different for different enzymes, even within the same cell or organism
Term
enzyme inhibitor
Definition
substance that binds to an enzyme and decreases its activity
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