exam 2 Flashcards
1
Q
light microscope
A
visible light is passed through the specimen and then through the glass lenses. the lenses refract/bend the light in such a way that the image of the specimen is magnified as it is projected into the eye or camera
2
Q
magnification
A
the ratio of an object’s image size to its real size
3
Q
resolution
A
is a measure of the clarity of the image
it is the minimum distance two points can be separated and stil be distinguished as separate points
4
Q
contrast
A
the difference in brightness between the light and dark areas of an image
5
Q
organelles
A
the membrane enclosed structures within eukaryotic cells
6
Q
electron microscope
A
focuses a beam of electrons through a specimen or onto its surface
7
Q
cytoplasm
A
to the region between the nucleus and plasma membrane, liquid
8
Q
plasma membrane
A
functions as a selective barrier that allows passage of enough oxygen, nutrients, and wastes to service the entire cell
9
Q
microvilli
A
thin projections from the cell’s surface that increase surface area without an appreciable increase in volume
10
Q
what increases faster
surface area or volume
A
volume
11
Q
nucleus
A
contains most f the genes in the eukaryotic cell
12
Q
nuclear envelope
A
encloses the nucleus separating its contents from the cytoplasm
double membrane
13
Q
nuclear lamina
A
netlike array of protein filaments that maintains the shape of the nucleus by mechanically supporting the nuclear envlopoe
14
Q
chromatin
A
the complex of dna and proteins making up chromosomes inside the nucleus
15
Q
nucleolus
A
prominent structure which appears through the electron microscope as a mass of densley stained granules and fibers adjoining part of the chromatin
ribsonomal rna is synthesized from instructions in the dna
proteins imported from the cytoplasm are assembled with rRNA into large and small subunits of ribosomes
16
Q
ribosomes
A
complexes made of ribosomal RNA and protein, are the cellular components that carry out protein synthesis
17
Q
free ribosomes
A
suspended in cytoplasm
18
Q
bound ribosomes
A
attached to the outside of the ER or nuclear envelope
19
Q
endomembrane system
A
includes: nuclear envelope, ER, golgi, lysosomes, and various kinds of vesicles and vacuoles, and the plasma membrane
this system carries out a variety of tasks in the cell, including synthesis of proteins, transport of proteins into membranes and organelles or out of the cell, metabolism
20
Q
vesicles
A
membrane sacs that transport things in the cell and out
21
Q
endoplasmic reticulum
A
extensive network of membranes that it accounts for more than half of the total membrane in many eukaryotes
the er consists of a network of membranous tubules and sacs called cisternae. the er membrane separates the internal compartment of the er, called the er lumen (cavity) or cisternal space, from the cytosol
22
Q
smooth er
A
no ribosomes
synthesis of lipids, metabolism of carbohydrates, detoxyfication of drugs and poisons, storage of calcium ions
23
Q
rough er
A
has ribosomes
secretes proteins produced by bound ribosomes (most are glycoproteins)
also produces membrane
24
Q
transport vesicles
A
vesicles in transit form one part of the cell to another
25
golgi apparatus
products of the ER are modified and stored and then sent to other destinations
consists of flattened membranous sacs-cisternae-looking like a stack of pita bread
26
cis and trans faces of golgi
cis face near the er where stuff comes in
| trans face gives rise to vesicles that pinch off and travel to other sides
27
lysosome
membranous sac of hydrolytic enzymes that an animal cell uses to digest (hydrolyze) macromolecules
28
phagocytosis
engulfing smaller organisms or food particles
29
autophagy
lysosomes use their hydrolytic enzymes to recycle the cell's own organic material
30
vacuoles
large vesicles derived from the er and golgi
integral part of cell's endomembrane system
vacuolar membrane is selective in transporting solutes and the solution inside a vacuole differs in composition from the cytosol
31
food vacuoles
formed by phagocytosis
| store food and break down food and things
32
contractile vacuoles
pump excess water out of the cell, thereby maintaining a suitable concentraton of ions and molecules inside the cell
33
central vacuole
plant cells
develops by the coalescence of smaller vacuoles
cell sap is the plant cell's main repository of inoranic ions, including potassium and chloride
major role in the growth of plant cells
34
endosymbiont theory
that an early ancestor off eukaryotic cells engulfed an oxygen-using non photosythetic prokaryotic cell. eventually, the engulfed cell formed a relationship with the host cell in which it was enclosed, becoming an edosymbiont. over the course of evolution this merged into a eukaryotic cell with a mitochondria and later the same happened with a chloroplast, creating plant cell
35
mitochondria
sites of cellular respiration, the metabolic process that uses oxygen to generate atp by extracting energy from sugars, fats and other fuels
36
cristae
infoldings of the inner membrane
37
intermembrane space (mitochondria)
narrow region between hthe inner and outer membranes in mitochondria
38
mitochondrial matrix
enclosed by the inner membrane
contains many different enzymes as well as the mitochondrial dna and ribosomes
enzymes in the matrix catalyze some of the steps of cellular respiration
39
chloroplasts
found in plants and algae, sites of photosynthesis. these organelles convert solar energy to chemical energy by absorbing sunlight nd using it to drive the synthesis of organic compounds such as sugars from co2 and water
40
chlorophyll
green pigment in chloroplasts
41
thylakoids
flattened interconnected sacs
42
granum
each stack of thylakoids
43
stroma
fluid outside the thylakoids
| containes chloroplast DNA and ribosomes as well as many enzymes
44
plastids
specialized family of closely related plant organelles
| contains chloroplast
45
peroxisome
specialized metabolic compartment bounded by a single membrane
contain enzymes that remove H2 atoms from certain molecules and transfer them to oxygen (o2) producing hydrogen peroxide (H2O2)
detoxify alcohol and other harmful compounds by transferring h2 from the poisons to o2
also contains an enzyme tha converts h2o2 to water
46
cytoskeleton
network of fibers extending throughout the cytoplasm
| major role in organizing the structures and activities of cell
47
motor proteins
interacts with the cytoskeleton, work together with plasma membrane molecules to allow whole cells to move along fibers outside the cell
cell motility
48
microtubules
hollow rods constructed from a globular protein called tubulin
a-tubulin and B-tubulin.
microtubules grow in length by adding tubulin dimers
shape and support cell and serve as tracks along which organelles equipped with motor proteins can move
49
centrosomes
region that is located near the nucleus and is considered a microtubule organizing center
these microtubules function as comporession resisting girders of the cytoskeleton
50
centrioles
inside the centrosome is a pair of these
each are composed of 9 sets of triplet microtubules arranged in a ring
before an animal cell divides, the centrioles replicate
51
flagella
limited to just one or a few per cell and are longer than cilia
has an undulating motion like the tail of a fish
52
cillia
occur in large numbers on the cell surface
work like oars, alternating power and recovery strokes
a single cillium may also act as a signal recieving atenna
53
basal body
9+0 pattern
microtubule assembly of a cillium or flagellum is anchored in the cell by one of these which is structurally like a centriole
54
dyneins
large motor proteins are attached along each outer microtubule doublet
55
microfilaments
thin solid rods
also called actin filaments because they are built from molecules of actin, a globular protien
twisted double chain of actin subunits
56
myosin
thousands of actin filaments and thicker filaments of a motor protein that interact to cause contraction of muscle cells
57
intermediate filaments
named for their diameter, which is larger than the diameter of microfilaments but smaller than that of microtubules
each type is constructed from a particular molecular subumit belonging to a family of proteins whose members include the keratins in hair and nails
58
cell wall
extracellular structure of plant cells that distinguishes them from animal cells
protects the plant cell
maintains its shape
prevents excessive uptake of water
59
primary cell wall
relatively thin and flexible wall
60
middle lamella
between primary walls of adjacent cells, a thin layer rich in sticky polysaccharides called pectins
61
secondary cell wall
not required
between plasma membrane and primary wall
strong and durable matrix that affords the cell protection and support
62
extracellular matrix
| ecm
everything outside the cell and between cells
| most ingredients are glycoproteins and other carb-containing molecules secreted by the cells
63
collagen
most abundant glycoprotein in the ecm of animal cells
forms strong fibers outside the cells
40% of protein in human body
64
proteoglycans
consists of a small protein with many carb chains covalently attached
proteoglycan complex consists of hundreds of proteoglycan molecules attached non-covalently to a single long polysaccharide molecule
65
fibronectin
attached cell to ecm
| bind to cell receptor proteins
66
integrins
proteins bult into cell membrane
67
pasmodesmata
membrane lined channels filled with cytosol
| unify most of a plant into one living continuum
68
tight junctions
plasma membranes very tightly pressed against each other, bound together by specific proteins
in skin cells make us water tight
69
desmosomes
fasten cells together into strong sheets
| muscle cells
70
gap junctions
similar in their function to plasmodesmata in plants
| necessary for communication between cells in many types of tissues
71
selective permeability
it allows some substances to cross it more easily than others (plama membrane)
72
amphipathic molecule
it has both a hydrophobic and hydrohilic region
| ex) phospholipid
73
fluid mosaic model
membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids
74
unsaturated membrane fluidity
unsaturated hydrocarbon tails (kinked) prevent packing, enhancing membrane fluidity at all temperatures
75
saturated membrane fluidity
saturated hydrocarbon tails pack together, lowering membrane fluidity making it easier to freeze
76
cholesterol in membrane and fluidity
reduces membrane fluidity at moderate temperatures by reducing phospholipid movement
but at low temperatures it hinders solidification by disrupting the regular packing of phospholipids
77
integral proteins
penetrate the hydrophobic interior of the lipid bilayer
the majority are transmembrane proteins, which span the membrane; other integral proteins extend only partway into hydrophobic interior
78
peripheral proteins
not embedded in lipid bilayer at all
appendages loosely bound to the surface of the membrane
often exposed parts of integral proteins
79
glycolipids
carbs bound to the plasma membrane directly
80
glycoproteins
carbs bound to the integrins or peripheral proteins
81
transport proteins
hydrophillic substances avoid contact with the lipid bilayer with transport proteins
82
channel proteins
hydrophillic channel that certain molecules or atomic ions use as a tunnel through membrane
this is protein
83
aquaporins
channel proteins for water
84
carrier proteins
transport proteins that hold onto their passengers and change shape in a way that shuttles them across the membrane
85
diffusion
the movement of particles of any substance so that they tend to spread out in the available space
each molecule moves randomly but ends up reaching equilibrium
86
concentration gradient
region along which the density of a substance increases or decreases
87
passive transport
diffusion is passive because the cell does not have to expend energy to make it happen
88
osmosis
diffusion of free water across a selectively permeable membrane
89
tonocity
the ability of a surrounging solution to cause a cell to gain or lose water
the tonocity of a solution depends in part on its concentration of solutes that cannot cross the membrane relative to that inside the cell
90
isotonic
same environment
| no net movement of water across plasma membrane
91
hypertonic
more non penetrating solutes
| cell will lose water, shrivel and probably die in a hypertonic solution
92
hypotonic
less solute and more water the cell will swell and lyse
93
osmoregulation
controlling solute concentrations and water balance
94
turgid
very firm
| healthy for plant cells
95
flaccid
isotonic
| limp
96
plasmolysis
plant wilt and can lead to plant death
| hypertonic
97
facilitated diffusion
many polar molecules and ions impeded by the lipid bilayer of the membrane diffuse passively with the help of transport proteins that span the membrane
no energy used
98
ion channels
chanells that transport ions
99
gated channels
open or close in response to a stimulus
| most ion channels
100
active transport
cell uses energy to transport against electrochemical gradient
101
sodium-potassium pump
active transport
exchanges Na+ for K+ across the plasma membrane for animal cells
page 5.14
102
membrane potential
voltage across memebrane
103
electrochemical gradient
combination of forces acting on an ion
| ie. voltage and concentration
104
electrogenic pump
a transport protein that generates voltage across a membrane
105
proton pump
actively transports protons outside cell to encourage other molcules in
106
cotransport
a single atp powered pump that transports a specific solution can inderectly drive the active transport of several other solutes
107
exocytosis
the cell secretes certain biological molecules by the fusion of vesicles with the plasma membrane
108
endocyosis
cell takes in molecules and particulate matter by forming new vesicles from the plasma membrane
109
phagocytosis
cell engulfs a particle by wrapping pseudopodia around it and packaging it within a membranous sac called a food vacuole
110
pinocytosis
cell continually gulps droplets of extracellular fluid into tiny vesicles
nonspecific for substances it transports
111
receptor mediated endocytosis
specialized type of pinocytosis that enables the cell to acquire bulk quantities of specific substance, even though those substance may not be ver concentrated in the extracellular fluid
112
local regulators
travel only short distances
113
paracrine signaling
a secreting cell acts on nearby target cells by discharging molecules of a local regulator (a growth factor, for example) into the extracellular fluid
114
synaptic signaling
a nerve cell releases neurotransmitter molecules, into a synapse, stimulating the target cell
can be local and long distance depending on length of synapse
115
hormones for long distance signalling
specialized cells release hormone molecules, which travel via the circulatory system to other parts of the body, where they reach target cells that can recognize and respond to the hormones
116
reception
target cell's detection of a signaling molecule coming from outside cell
117
transduction
step or series of steps that converts the signal to a form that can bring about a specific cellular response
usually requires a sequence of changes in a series of different molecules- a signal transduction pathway
118
response
transduced signal triggers cellular response
| may be almost any imaginable cellular activity
119
ligand
=signalling molecule
| =first messenger
120
g-protein coupled receptor
cell surface transmembrane receptor that works with the help of a g protein
121
g protein
a protein that binds the energy rich molecule GTP, similar to ATP but with guanine
122
ligand-gated ion channel
membrane receptor that has a region that can act as a gate for ions when the receptor assumes a certain shape triggered by a ligand
123
intracellular receptors
these ligands have to be hydrophobic to pass through the plasma membrane to reach receptors in cytoplasm or nucleus
124
transcription fators
control which genes are transcribed into mRNA in a particular cell at a particular time
125
protein kinase
enzyme that transfers phosphate groups from ATP to a protein
| such enzymes are widely involved in signalling pathways in animals, plants and fungi
126
protein phosphatases
(PP)
| enzymes that can rapidly remove phosphate groups from proteins, a process called dephosphorylation
127
second messengers
small non protein water soluble molecules or ions
can readily spread throughout the cell by dffusion
-cyclic AMP
-Ca2+
128
cyclic AMP
cyclic adenosine monophosphate
| each molecule of adenylyl cyclase can catalyze the synthesis of many molecules of cAMP
