Cell Biology Flashcards
hierarchy of life (in ascending order)
atoms
molecules
organelles
cells
tissues
organs
systems
organisms
population
community
ecosystem
biosphere
2 main categories of organisms
prokaryotes
eukaryotes
prokaryote
unicellular organism which lacks membrane-bound nucleus, mitochondria, or other membrane-bound organelles
literal definition of “prokaryote”
before nucleus
before nut
before kernel
eukaryote
multicellular organism which contains membrane-bound nucleus, mitochondria, and other membrane-bound organelle
literal definition of “eukaryote”
good nucleus
true nucleus
good nut
true nut
good kernel
true kernel
characteristics of life
functions of life
reproduction
nutrition
metabolism
growth
reaction to environment (response)
homeostasis
excretion
reproduction
creation of new but similar organisms
also known as “gettin’ down to business”
nutrition
procurement of food to provide energy and materials needed for growth
metabolism
chemical reactions inside cells to release energy
sum of all reactions that occur in an organism
metabolic rate
rate at which metabolism occurs
requirements for metabolism to occur
absorbance of reactants by cell (through plasma membrane)
removal of waste products from cell (through plasma membrane)
relationship between surface area and metabolic rate of cell
direct relationship
reaction to environment
response
reaction to stimuli and changes in environment
growth
physical enlargement of a living thing
homeostasis
steady state of bodily functions
excrement
process of getting rid of waste
3 principles of cell theory
all living things are made of cells
cells are smallest units of life
existing cells come from other cells
3 pieces of evidence to support cell theory
consistent appearance of all living things to be composed of cells when observed
requirement of cooperation of all organelles for life processes
lack of evidence that proves spontaneous generation or abiogenesis
discrepancy
exception to general trend
3 atypical examples in regards to cell theory
striated muscle tissue
giant algae
aseptate fungi
discrepancy between striated muscle tissue and cell theory
much larger than typical animal cell
able to have many (sometimes up to 100) nuclei
discrepancy between giant algae and cell theory
much larger than most unicellular organisms (able to grow up to 100nm long with only 1 nucleus)
discrepancy between aseptate fungi and cell theory
has no septa to divide cell (causes uninterrupted tube-like structure with many nuclei)
4 similarities between all cells
surrounded by membrane
contains genetic materials which store all instructions needed for cell’s activities
catalyzes chemical reactions by utilizing enzymes produced within cell
has unique energy release system that powers all activities
complexity of structure of prokaryotes (and why)
complex (in order to carry out every function of life within one cell)
number of cells in adult human body
10,000,000 cells
cooperative group
collection of cells which work together in multicellular organisms
has no cells which act as ‘leader’ or ‘supervisor’
emergent property
emergent property of a system
property of system as a whole (rather than components which make up system)
emergence
way that complex systems and patterns arise from many small and relatively simple interactions
reductionism
scientific practice of analyzing and describing a complex phenomenon by studying smaller parts of it
predictability of emergent properties through reductionism
unpredictable
cell differentiation
process by which acquires more specialized function and purpose
cell potency
ability of a eukaryotic cell to differentiate into other cells
totipotent cell
eukaryotic cell which has ability to differentiate into any other type of cell
specialized cell
eukaryotic cell which is modified to carry out particular function
benefits of cell specialization
efficiency
development of ideal structure (for assigned function)
creation of enzymes needed to carry out all chemical reactions associated with assigned function
tissue
group of cells which differentiate in same way to perform same function
gene expression
way in which a gene is used within a particular cell
dictates cell differentiation
stem cell
eukaryotic cell at early stages of embryonic development
capable of dividing many times to produce large amounts of tissue
able to differentiate into any type of cell (totipotent)
2 key properties of stem cells
ability to divide again and again to produce copious quantities of new cells
totipotency
3 main types of stem cells
embryonic stem cells
cord blood stem cells
adult stem cells
embryonic stem cell
stem cell which originates from a fertilized human egg (approximately 4 to 5 days post-fertilization)
totipotent
therapeutic uses of embryonic stem cells
tissue regeneration
treatment and healing of diseases
(possibly in future) growth of replacement organs
non-therapeutic uses of embryonic stem cells
large-scale production of striated muscle fibers (or meat) for human consumption
cord blood stem cell
stem cell which originates from blood that remains in placenta and attached umbilical cord following childbirth
easily obtainable and stored
has limited capacity to differentiate into different types of cells (pluripotent)
adult stem cell
somatic stem cell
stem cell which originates from some adult tissues
extremely difficult to obtain (located in only 3 known locations extremely deep in tissues)
in vitro fertilization
process of fertilization where an egg is combined with sperm outside the body
cell division
process by which parent cell divides into 2 or more daughter cells
products from cell division of specialized cells
2 or more daughter cells of same specialization
products from cell division of stem cells
2 or more daughter stem cells
importance of surface area of cell for metabolism
substances cannot enter as quickly as required and waste would accumulate in cell (because waste would be produced faster than it could be expelled) if surface area were too small
importance of surface area of cell on production and loss of heat
cell may overheat (because metabolism produces heat faster than lost over cell’s surface) if surface area were too small
microscopy
technical field of using microscopes to view objects and areas of objects that cannot be seen with the naked eye
microscope
instrument used to see objects that are too small to be seen by naked eye
important parameters of microscopy
magnification
resolution
contrast
(microscopy)
magnification
ratio of image size to real size
(microscopy)
resolution
clarity of image
minimum distance of 2 distinguishable points
(microscopy)
contrast
visible differences in parts of a sample
2 main types of microscopes
light microscope
electron microscope
light microscope
optical microscope
microscope that commonly uses visible light and a system of lenses to magnify images of small objects
maximum magnification of most light microscopes
maximum magnification of most optical microscopes
approximately 1,000 times the actual size of sample
electron microscope
microscope that uses beam of accelerated electrons as source of illumination
2 types of electron microscopes
scanning electron microscope
transmission electron microscope
scanning electron microscope
electron microscope which focuses beam of electrons onto surface of specimen
transmission electron microscope
electron microscope which focuses beam of electrons through specimen
(cell structure)
plasma membrane
biological membrane that separates interior of all cells from extracellular matrix
composed of phospholipid bilayers, membrane proteins, and cholesterol
found in every type of cell
(cell structure)
cytosol
cytoplasmic matrix
everything inside of cell except for nucleus
found in every type of cell
(cell structure)
cytoplasm
all the liquidy stuff inside cell
found in every type of cell
(cell structure)
mitochondrion
double-membrane-bound organelle which produces most of cell’s supply of energy (in form of ATP)
found in eukaryotes
2 parts within mitochondrion
intermembrane space
mitochondrial matrix
(cell structure)
cytoskeleton
complex and dynamic network of interlinking protein filaments that extends from cell nucleus to cell membrane
provide structure and support to shape of cytoplasm
found in eukaryotes
(cell structure)
3 components of cytoskeleton
microtubules
intermediate filaments
actin filaments (microfilaments)
(cell structure)
microtubule
cytoskeletal structural components composed of polymers of tubulin
found in eukaryotic cells
(cell structure)
intermediate filament
cytoskeletal structural component composed of family of related proteins sharing common structural and sequence features
found in eukaryotes
(cell structure)
microfilament
actin filament
cytoskeletal structural component that is primarily composed of polymers of actin
found in eukaryotes
(cell structure)
motor protein
protein which moves throughout cytoplasm of cell
converts energy into mechanical work through hydrolysis of ATP
responsible for most active transport of proteins and vescicles in cell
found in animal cells
(cell structure)
nucleus
membrane-bound organelle which contains all of cell’s genome (except for small fraction of mitochondrial DNA)
found in most eukaryotes
(cell structure)
nucleolus
largest structure in nucleus of cell
found in eukaryotes
examples of cells without nuclei (enucleated cells)
prokaryotes
mammalian red blood cells
(cell structure)
nuclear envelope
double-membrane-bound organelle which surrounds nucleus
protects nucleus of cell
has many nuclear pores that allow materials to move between cytosol and nucleus
found in eukaryotes
(cell structure)
nuclear pore
part of large complex of proteins (nuclear pore complex) which spans across nuclear envelope
allows transport of molecules across nuclear envelope (including RNA and ribosomal proteins)
found in eukaryotes
(cell structure)
chromatin
complex of DNA and protein located in nucleus of cells
found in eukaryotic cells
(cell structure)
endoplasmic reticulum
type of organelle that forms interconnected network of cisternae
adjacent to nucleus in most cells
found in eukaryotes
cisternae
flattened membrane disk or sac of endoplasmic reticulum and Golgi apparatus
(cell structure)
smooth endoplasmic reticulum
membrane-bound organelle responsible for synthesis of lipids and steroid hormones, detoxification of harmful metabolic byproducts, and storage and metabolism of calcium ions within cell
composed of cisternae
scarce in most cells
found in eukaryotes
(cell structure)
rough endoplasmic reticulum
membrane-bound organelle responsible for production of proteins
composed of cisternae
covered by ribosomes
found in eukaryotes
structural difference between smooth endoplasmic reticulum and rough endoplasmic reticulum
surface of smooth endoplasmic reticulum does not contain ribosomes
surface rough endoplasmic reticulum contains ribosomes
(cell structure)
Golgi apparatus
Golgi complex
membrane-bound organelle responsible for secretion and intracellular transport
composed of cisternae
attached to vesicles and folded membranes within cytoplasm
found in eukaryotes
2 main networks of Golgi apparatus
cis Golgi network
trans Golgi network
cis Golgi network
“receiving” side of Golgi apparatus
trans Golgi network
“shipping” side of Golgi apparatus
structural difference between endoplasmic reticulum and Golgi apparatus
endoplasmic reticulum has elongated cisternae (sometimes) with attached ribosomes
Golgi apparatus has curved cisternae with no attached ribosomes and many vescicles nearby
(cell structure)
lysosome
single-membrane-bound organelle formed from vesicles near Golgi apparatus
contain digestive enzymes which can be used to break down ingested food (found in vesicles), organelles, or even entire cells
found in eukaryotes
autophagy
process by which cell eats itself
(cell structure)
peroxisome
double-membrane-bound organelle responsible for catabolism of particular fatty acids, amino acids, and polyamines
produces hydrogen peroxide
found in eukaryotes
(cell structure)
centrosome
membrane-bound organelle that serves as the main microtubule-organizing center of the animal cell and regulator of cell-cycle progression
composed of two centrioles arranged at right angles to each other
found in animal cells
(cell structure)
centriole
cylindrical organelle responsible for helping with development of spindle fibers (used in cell division)
composed mainly of a protein called tubulin
located near nucleus of cell
found in eukaryotes
(cell structure)
cell wall
tough structural layer surrounding cell membrane
found in prokaryotes and plant cells
(cell structure)
vacuole
membrane-bound organelle which are filled with water containing inorganic and organic molecules
may contain solids which have been engulfed
derived from endoplasmic reticulum and Golgi apparatus
found in every type of cell
(cell structure)
central vacuole
membrane-bound organelles which hold organic compounds and water
found in plant cells
(cell structure)
contractile vacuole
membrane-bound organelle which pumps excess water out of cell
found in freshwater plants
(cell structure)
plastid
type of organelle in cytoplasm of cell which contains pigment or food
found in plant cells
(cell structure)
chloroplast
plastid that conducts photosynthesis
contains chlorophyll
found in plant cells
photosynthesis
conversion of light into energy
(cell structure)
granum
stack of thylakoids within chloroplast
found in plant cells
(cell structure)
thylakoid
membranous sac within chloroplast
located in granum within chloroplast
found in plant cells
(cell structure)
stroma
internal fluid of chloroplast
(cell structure)
capsule
polysaccharide layer that lies outside cell wall
found in prokaryotes
(cell structure)
pili
long hair-like appendage found on surface of cell
found in prokaryotes
(cell structure)
fimbriae
short hair-like appendage on surface of cell
found in prokaryotes
(cell structure)
flagellum
lash-like appendage that protrudes from cell body
assists with locomotion and sensory
found in every type of cell (mainly prokaryotes)
(cell structure)
cilium
slender organelle which protrudes from surface of cell
assists with sensory
found in eukaryotes
(cell structure)
nucleoid
nucleoid region
irregularly shaped region within cell that contains all or most genetic material (genophore)
found in prokaryotes
(cell structure)
vescicle
structure within or outside a cell used to transport particles
consists of liquid or cytoplasm enclosed in phospholipid bilayer
found in every type of cell
(cell structure)
ribosome
organelle which serves as site of biological protein synthesis
links together amino acids in order specified by messenger RNA (mRNA) molecules
located on surface of rough endoplasmic reticulum within eukaryotes
found in every type of cell
(cell structure)
nuclear lamina
fibrillar network inside nucleus of most cells
maintains shape of nucleus
found in eukaryotes
(cell structure)
extracellular matrix
three-dimensional network of extracellular glycoproteins (such as collagen, proteoglycans, and fibronectin)
binds to receptor proteins in plasma membrane (integrin)
found around every type of cell (mainly animal cells)
functions of extracellular matrix
support
adhesion
movement
regulation
(cell structure)
endomembrane system
components which are continuous with or connected to plasma membrane (via transfer by vescicles)
components of endomembrane system
nuclear envelope
endoplasmic reticulum
Golgi apparatus
lysosomes
vacuoles
plasma membranes
(cell structure)
phospholipid bilayer
main component of polar cell membrane
made of two layers of amphipathic phospholipid molecules
semi-permeable
found in every type of cell
hydrophilic substance
substance which is attracted to water
hydrophobic substance
substance which is not attracted to water
amphipathic substance
substance with hydrophilic portion and hydrophobic portion
phospholipid
amphipathic lipid which contains 2 hydrocarbon chains attached to 1 phosphate group by a glycerol molecule
structure of phospholipid
1 polar phosphate group (hydrophilic “head”)
2 nonpolar hydrocarbon chains (hydrophobic “tails”)
phosphate group
hydrophilic “head”
polar ends of phospholipid molecules
face outwards on both sides of plasma membrane
attached to 2 hydrocarbon chains
hydrocarbon chain
hydrophobic “tail”
nonpolar end of phospholipid molecules
face inwards on both sides of plasma membrane
attached to phosphate group
effect of double bonds in hydrocarbon chains of phospholipids
makes phospholipids to sit further away from each other (causes semi-fluid state of plasma membranes)
(cell structure)
membrane protein
proteins found in or on surface of plasma membrane
found in every type of cell
functions of membrane protein
transport channels for passive transport of materials into or out of cell
enzymatic activity
cell-to-cell communication (signal transduction)
cell-to-cell recognition
cell-to-cell adhesions (tight junctions)
attachment to cytoskeleton and extracellular matrix
types of membrane proteins
integral membrane protein
peripheral membrane protein
integral membrane protein
integral protein
protein embedded in between hydrocarbon tails of plasma membrane
hydrophobic on exterior
sometimes hydrophilic on interior (depending on function)
has specific orientation (positioned specifically for needs of cell)
peripheral membrane protein
peripheral protein
protein which sits on surface of plasma membrane
hydrophilic exterior (prevents it from embedding in plasma membrane)
has specific orientation (positioned specifically for needs of cell)
deciding factor of protein content of plasma membrane
function of plasma membrane (more active membranes require higher protein content)
(cell structure)
cholesterol
lipid (neither fat nor oil)
steroid (gives it 4-ring structure)
mostly hydrophobic (except for hydroxyl group at one end of molecule)
found in animal cell membranes
location of cholesterol in plasma membrane
between phospholipids
functions of cholesterol in plasma membrane
stabilize fluidity of plasma membrane (regardless of temperature or other factors)
help plasma membrane curve to form vesicles
3 plasma membrane models
Gorter and Grendel model
Davson and Danielli model (sandwich model)
Singer and Nicolson model (fluid mosaic model)
(plasma membrane model)
Gorter and Grendel model
proposed in 1920
described plasma membrane as a bilayer
claimed that membranes also contained proteins (without specifying their location)
succeeded by Davson and Danielli model (sandwich model)
(plasma membrane models)
Davson and Danielli model
sandwich model
proposed in 1935
described phospholipid bilayer that lies between 2 layers of globular proteins (like sandwich)
had many discrepancies
succeeded by Singer and Nicholson model (fluid mosaic model)
problems with Davson and Danielli model
freeze-etched electron micrographs (caused fractures along lines of weakness through membrane)
structure of membrane proteins (variance in shape and size)
(plasma membrane models)
Singer and Nicholson model
fluid mosaic model
proposed in 1972
described plasma membrane as 2-dimensional liquid that restricts lateral diffusion of membrane components
explained concept of integral and peripheral proteins
most-accepted model of plasma membrane to date
shape of vesicles
spherical
function of vesicles
facilitation of exocytosis or endocytosis
causes of vesicle movement
transportation of contents of vesicle
transportation of proteins in vesicle membrane
endocytosis
process by which a cell uses its plasma membrane to engulf substances
2 types of endocytosis
phagocytosis
pinocytosis
phagocytosis
process by which a cell uses its plasma membrane to engulf large particles (≥ 0.5 μm)
type of endocytosis
pinocytosis
process by which a cell uses its plasma membrane to engulf small particles suspended in extracellular fluid
type of endocytosis
exocytosis
process by which a cell uses its plasma membrane to remove substances
2 types of exocytosis
secretion
expulsion
secretion
process by which a cell uses its plasma membrane to remove useful substances (not waste products)
type of exocytosis
expulsion
process by which a cell uses its plasma membrane to remove waste products (not useful substances)
type of exocytosis
2 methods of particle movement across plasma membrane
passive transport
active transport
passive transport
movement of ions and other atomic or molecular substances across plasma membrane without need of energy input
3 types of passive transport
simple diffusion
facilitated diffusion
osmosis
diffusion
net movement of anything from region of higher concentration to region of lower concentration
simple diffusion
spreading out of particles from region of higher concentration to a region of lower concentration across plasma membrane
involves particles passing between phospholipids
type of passive transport
particles which are able to undergo simple diffusion
small, nonpolar, uncharged, and hydrophobic molecules
facilitated diffusion
spreading out of particles from region of higher concentration to a region of lower concentration across plasma membrane
involves particles passing through protein channels
type of passive transport
particles which are able to undergo facilitated diffusion
polar and hydrophilic molecules
large ions
protein channel
protein that allows transport of specific substances across plasma membrane
osmosis
diffusion of water from region of higher concentration to a region of lower concentration across plasma membrane
involves water molecules passing between phospholipids
type of passive transport
tonicity
ability of surrounding solution to cause cell to gain or lose water
isotonic solution
solution in which concentration is same inside and outside of cell
involves no net water movement across plasma membrane
hypertonic solution
solution in which concentration is less inside than outside of cell
involves cell losing water
hypotonic solution
solution in which concentration is greater inside than outside of cell
involves cell gaining water
natural tonicity of animal cells
isotonic
state of hypertonic animal cell
shriveled
state of hypotonic animal cell
lysed
natural tonicity of walled cells
hypotonic
state of isotonic walled cell
flaccid
limp
state of hypertonic walled cell
plasmolyzed
aquaporin
integral membrane proteins that serve as channels in transfer of water and small solutes across plasma membrane
cells with aquaporins
cells which need to move large amounts of water
active transport
spreading out of particles from region of lower concentration to a region of higher concentration across plasma membrane
involves particles passing through globular pump proteins
requires energy (in form of ATP)
endosymbiotic theory
evolutionary theory which states that an early ancestor of eukaryotic cells engulfed a nonphotosynthetic prokaryotic cell
