Unit 2 Flashcards
1
Q
What are the 4 molecules in cell membranes?
A
phospholipids, proteins, carbohydrates, cholesterol
2
Q
What are the characteristics of membranes?
A
dynamic and fluid
3
Q
In an aqueous solution, what do phospholipids do?
A
arrange themselves with polar heads facing outward and hydrophobic tails facing inward
4
Q
Are phospholipids amphipathic?
A
yes
5
Q
What are integral membrane proteins?
A
Embedded in the membrane
May have one or more alpha-helices that span the membrane or beta-pleated sheets that span the membrane
6
Q
What is a peripheral membrane protein?
A
attached to lipid bilayer but doesn’t pass all the way through it
7
Q
Where are carbohydrates found in the cell membrane?
A
Always found on the exterior surface of cellular membranes
8
Q
What is a glycoprotein?
A
Protein that has a carbohydrate attached to it
9
Q
What is a glycolipid?
A
Lipids with carbohydrates attached
10
Q
What is the purpose of cholesterol?
A
Essential for membrane function and structure
11
Q
Does the membrane have selective permeability?
A
Yes
Has to pass through the hydrophobic core of the membrane
12
Q
Can large molecules fit through the phospholipid bilayer?
A
no
13
Q
Do large, uncharged polar molecules pass through the phospholipid bilayer?
A
no
Glucose and sucrose
14
Q
Do Small uncharged polar molecules pass through the phospholipid bilayer?
A
no
Glycerol can’t, but water can pass through
15
Q
Can small nonpolar molecules pass through the phospholipid bilayer?
A
yes
Oxygen gas, carbon dioxide, nitrogen gas
16
Q
Can small ions pass through the phospholipid bilayer?
A
no
Chlorine, potassium, sodium
Charges prevent them from crossing the hydrophobic core
17
Q
Does hydrocarbon saturation affect the permeability of membranes?
A
yes
18
Q
What are the characteristics of Lipid bilayer with short and unsaturated hydrocarbon tails?
A
higher permeability and fluidity
Still excludes anything with a charge
19
Q
What are the characteristics of Lipid bilayer with long and saturated hydrocarbon tails?
A
Lower permeability and fluidity
20
Q
What is the fluid mosaic model?
A
membranes are always moving, but the components of the membrane shift around
membrane behaves almost like water
21
Q
What is the most significant molecule present in the cell membrane?
A
phospholipid bilayer
22
Q
What are the functions of proteins in the membrane?
A
Transport (Different things get through the membrane through the protein channel)
23
Q
What do glycolipids do and where are they on the membrane?
A
identifies different cell types
outside (extracellular) side
24
Q
What are the functions of glycoproteins and where are they on the membrane?
A
identifies different types of cells, receptors on the cell surface, cell-to-cell signaling, viruses use glycoproteins to get into the cell
outside (extracellular) side
25
What are the characteristics of R-groups that make up alpha-helices and beta-pleated sheets? What kinds of bonds are formed between the backbone of nonadjacent amino acids?
nonpolar and hydrophobic amino acids
hydrogen bonds
26
What are the characteristics of cholesterol and what are the functions of cholesterol?
hydrocarbon rings, hydrophobic, hydroxyl group on the end of the ring structure
can get into the hydrophobic interior of the membranes, helps keep saturated fatty acid chains separated, creates space in the membrane, is important for membrane fluidity and permeability, helps prevent membranes from freezing at cold temperatures, helps keep unsaturated fatty acid phospholipid molecules stuck together
27
What does selective permeability do?
controls what is allowed in and out of the cell
28
Do organisms need to maintain homeostasis?
yes
Need a certain water and salt balance
Need a pH balance
29
How does selective permeability maintain homeostasis?
by regulating what gets across the membrane
30
How does water get through the cell membrane?
through aquaporin channel
31
What is passive transport?
when substances move from an area of higher concentration to an area of lower concentration
32
Does passive transport require the input of energy?
no
33
Is diffusion passive or active transport?
passive
34
Do different substances have different diffusion rates?
yes
35
What affects rate of diffusion?
mass of the molecules (higher mass moves slower)
temperature (increased temp=increased motion, decreased temp=decreased motion)
36
What is facilitated transport?
Diffusion across the membrane but with the assistance of another protein
37
What are the 3 types of proteins in facilitated transport?
channel proteins
gated channel proteins
carrier proteins
38
What are channel proteins?
Protein that passes entirely through the plasma membrane
39
What kind of protein is a channel protein?
transmembrane
40
What is the interior of the channel protein lined by?
hydrophilic amino acids
41
What is the exterior of the channel protein lined by?
hydrophobic amino acids
42
What do channel proteins do?
Allows charged, polar, large molecules a way to get through the membrane to move down their concentration gradient
43
Is the channel protein always open?
yes
44
How many types of molecules do channel proteins let through?
1
45
What are the characteristics of gated channel proteins?
Closed and some other substance needs to interact with the channel to open
46
Where are carrier proteins on the cell membrane?
embedded inside
47
What do carrier proteins do to transport molecules across the membrane?
change shape
48
Where do molecules bind to on the carrier protein and what does the carrier protein do in response?
extracellular part
causes carrier to allow that molecule inside and changes shape to deliver the molecule to the interior of the cell
49
Do carrier proteins transport slower or faster than channel proteins?
slower
50
What is osmosis?
Diffusion of water across a semipermeable membrane
51
What is the only thing osmosis transports?
water
52
What is the concentration gradient of water in osmosis?
The concentration gradient of water moves from a high concentration of water molecules to a low concentration of free water molecules
53
What is osmolarity?
Total solute concentration
54
What are characteristics of a solution with low osmolarity?
has a greater number of water molecules relative to the number of solute molecules
55
What are the characteristics of a solution with high osmolarity?
has fewer number of water molecules relative to the number of solute molecules
56
What is an isotonic solution?
The osmolarity of the solution in the petri dish has an equal solute concentration to the interior of the red blood cell
57
Do red blood cells have a net zero loss/gain of water in an isotonic solution?
yes, so cells maintain shape and size
58
What is a hypertonic solution?
increased concentration of solute outside of the cell, water wants to diffuse down its concentration gradient
59
What do cells want to do in hypertonic solutions to equilibrate?
Cells want to drive water out of the cell
60
Is there a net loss or gain of water in a hypertonic solution?
net loss, cells shrink
61
What is a hypotonic solution?
distilled water in solution decreasing concentration outside of the cell
62
Does water want to move in or out of the cell in a hypotonic solution?
water wants to move inside of the cell causing cells to expand or burst
63
What are electrochemical gradients?
electrical gradient and concentration gradient
64
What kinds of proteins and ions are in electrochemical gradients?
charged
65
How do ions move across the cell membrane?
through facilitated transport mechanisms
66
What are proteins labeled as in electrochemical gradients?
A
67
Do proteins move in and out of the cell easily?
no
68
What kind of charge do proteins carry?
overall negative charge
69
What kind of charge does the interior of the membrane have?
net negative charge
70
What kind of charge does the exterior of the membrane have?
net positive charge
71
Do cells have a higher concentration of potassium or sodium ions inside of the cell?
Potassium
72
Do cells have a higher concentration of potassium or sodium ions outside of the cell?
sodium
73
What is required to move substances across an electrochemical gradients?
an input of energy
74
What kind of energy is needed to move substances across an electrochemical gradient?
ATP generated through cell's metabolism
75
What is primary active transport?
moves ions across the membrane resulting in a difference of charge across the membrane
76
What is the charge dependent on in primary active transport?
ATP
77
What are the 3 kinds of transporter proteins?
uniports
symports
antiports
78
What are uniports?
carries one molecule or ion
79
What are symports?
carries 2 different molecules or ions, both in the same direction
80
What are antiports?
carries 2 different molecules or ions, but in different directions
81
What is the sodium potassium pump?
moves potassium into the cell, moves sodium outside of the cell
82
What is the ratio of movement for the sodium potassium pump?
3 sodium ions out of the cell
2 potassium ions into the cell
83
What side of the cell is the sodium potassium pump open to?
cytoplasmic side allowing sodium ions to enter
84
What does ATP hydrolysis do when the ATP molecule attaches to a protein? What does this do to the carrier?
takes off one phosphate group of ATP
causes carrier to change shape and release sodium ions to extracellular fluid
85
What happens with the sodium potassium pump when it binds to potassium ions? What does this result in?
attached phosphate releases
changes the pump shape
releases potassium ions into the cytoplasm
86
What is the concentration of sodium and potassium ions after ATP hydrolisis?
More sodium ions outside of the cell than inside
More potassium ions inside of the cell than outside
87
What are the charges of the sides of the cell after ATP hydrolisis?
Inside is slightly more negative than outside, which creates conditions needed for secondary transport
88
What is secondary active transport?
substances are taking advantage of the electrochemical gradient set up by primary active transport
89
Does secondary active transport require additional energy input to transport molecules across the membrane?
no
90
As sodium ion concentration build up outside membrane during secondary active transport, what do the ions do?
want to move down the gradient, other substances tag along and move across the membrane with sodium
91
What is glycocalyx?
the highly hydrophobic surface of carbohydrates that attracts water to the cell's surface
92
What is glycocalyx important for?
cell identification, self/non-self determination, embryonic development
93
What is the electrogenic pump?
a pump that creates a charge imbalance (a sodium-potassium pump)
94
What is phagocytosis?
condition of "cell eating"
cell takes in large particles
95
What is clathrin?
a protein that plays a crucial role in intracellular transport and endocytosis
96
What is pinocytosis?
cell drinking
takes in molecules the cell needs from extracellular fluid
97
What is potocytosis?
brings small molecules into the cell and transports them through the cell for their release on the other side
98
What is receptor-mediated endocytosis?
brings specific substances that are normally in the extracellular fluid into the cell
99
Is diffusion active/passive? What kind of material is transported?
passive
Small-molecular weight material
100
Is osmosis active/passive? What kind of material is transported?
passive
water
101
Is facilitated diffusion active/passive? What kind of material is transported?
passive
Sodium, potassium, calcium, glucose
102
Is primary active transport active/passive? What kind of material is transported?
active
Sodium, potassium, calcium
103
Is secondary active transport active/passive? What kind of material is transported?
active
Amino acids, lactose
104
Is phagocytosis active/passive? What kind of material is transported?
active
Large macromolecules, whole cells, or cellular structures
105
Is pinocytosis and potocytosis active/passive? What kind of material is transported?
active
Small molecules (liquids/water)
106
Is receptor-mediated endocytosis active/passive? What kind of material is transported?
active
Large quantities of macromolecules
107
How does cholesterol affect membrane permeability and fluidity?
cholesterol’s rings are inserted in the hydrophobic interior of the cell membrane and the polar group sticks out into the cytoplasm. Increases permeability and fluidity at low temperatures (keeps molecules spaces apart and when there is a high percentage of saturated fatty acids), decreases permeability and fluidity at high temperatures because phospholipid molecules are going to be spread apart (cholesterol will fill in gaps between phospholipid molecules and when there is a high percentage of unsaturated fatty acids)
108
How does aspirin increase lipid bilayer fluidity and permeability?
The hydrophobic part inserts itself into the membrane, and the polar parts extend out of the membrane and increase the space between phospholipids
109
Are proteins required to move substances across the membrane in facilitated diffusion?
yes
110
What are the kinds of prokaryote morphologies?
cocci (spherical)
bacilli (rod-shaped)
spirilli (spiral-shaped)
111
What are gram-positive bacteria?
Plasma membrane internal to peptidoglycan cell wall
When exposed to gram staining, they take up the stain
112
What are gram-negative bacteria?
outer membrane with peptidoglycan cell wall sandwiched between two membranes
When exposed to gram staining, the exclude the stain because of the outer membrane
113
What is gram staining used for?
to characterize bacteria to determine what kind of antibiotic can be used to treat a bacterial infection
114
How do prokaryotic cells reproduce?
through binary fission
115
What does binary fission do?
produces genetic clones
116
What are the steps of binary fission?
Genome is copied
Two copies of cellular chromosome
Cell synthesis new cell wall
Cell grows and copies are separated to opposite sides of cytoplasm
Cell forms two new cells
117
What are the gene transfer mechanisms in prokaryotes?
transformation
transduction
conjugation
118
What is transformation?
Bacterial cells take up DNA from the external environment
119
What is transduction?
Bacteriophage injects DNA into the host bacterial cell
120
What is conjugation?
DNA is transferred from one prokayote to another through pilus
121
What are pili?
short protrusions that allow bacteria to adhere to surfaces
122
What are sexual pili used for in conjugation?
used to exchange genetic material
123
What are extremophiles?
archaebacteria that grow in extreme conditions
Can grow at very high and low pHs, very high and low-temperature extremes, and very high salt and sugar concentrations
124
Describe the electrochemical gradient inside of the cell
more negative charge
negatively charged proteins and nucleic acids
higher concentration of potassium ions inside of the cell
125
Does the sodium-potassium pump allow ions to go against their concentration gradient?
yes
126
Describe the movement of sodium ions
Sodium ions flow back into the cell along their concentration gradient
Flowing into the cell flowing down their concentration gradient and charge gradient
127
Describe the movement of potassium ions
Potassium ions flow back out of the cell against their charge gradient
Concentration gradient favours potassium ions moving out
Potassium concentration is higher in the cell, so they want to move down their gradient by going to a lower concentration of potassium ions outside of the cell
Moving against their charge gradient
128
What is an enterocyte and how does secondary active transport occur in it?
potassium moves into the intestinal lumin (generates high concentration of potassium ions)
Sodium moves out of the intestinal lumen (generates high concentration of sodium ions)
Sodium flows down concentration gradient in a sodium-glucose transporter
Glucose tags along and flows against its gradient
Sodium-glucose transporter is a symporter
There is another transporter that transports glucose into blood vessels
129
What are the components of a typical prokaryotic cell?
capsule
flagella
cell wall
plasmid DNA
cytoplasm
ribosomes
doubles-stranded DNA
130
What is the capsule?
provides protection for immune recognition and allows cells to adhere to surfaces (bacteria in human mouth adhere to teeth)
made of polysaccharides
131
What is flagella made of and what does it do?
amade from microtubules and flagellin and moves cell
Spans from plasma membrane to outside of the cell
132
What is the cell membrane?
phospholipids
transport and energy transduction
133
What does the cell wall do?
provides protection and structure
eubacteria cell wall is made of peptidoglycan
134
What is plasmid DNA?
extragenomic DNA
small, circular double-stranded DNA
exchanged between bacterial cells
carries genes that resist antibiotics
135
What is the cytoplasm?
gel-like matrix
contains water, enzymes, ions, nutrients, wastes, and gases
136
What do ribosomes do?
synthesize proteins
137
What is double-stranded DNA genome contained in for prokaryotes?
the nucleoid (gram-negative)
138
What are halophiles? How are halophiles used in the energy industry?
bacteria that survive in high salt concentrations
produce biofuels with their unique enzymes and ability to ferment matter in saline conditions and can form salt-tolerant bacterial mats
139
Describe the features of Deinococcosu radiodurans and why are scientists so interested in this organism?
polextremophile
tolerates high doses of ionizing radiation
reconstructs its genome through DNA mechanisms
survives in dust
140
Do prokaryotes lack internal membranes?
yes
141
What is the genome for prokaryotes?
Double-stranded DNA with a single, circular chromosome
142
What are the 2 domains of prokaryotes?
eubacteria and archaebacteria
143
What is unique about eubacteria?
cell wall made of peptidoglycan
gram positive or gram negative
144
How do eukaryotic cells divide?
through mitosis or meiosis
145
What are the characteristics of archaebacteria cell walls?
carbohydrates
more rigid (extremophiles in cold environments)
less rigid (warm environments)
146
What is unique about the eubacteria cell wall?
peptidoglycan
147
What are characteristics of eubacteria cell membranes?
lipid bilayers with unbranched fatty acids
148
What are the characteristics of archaebacteria cell membranes?
Lipid monolayer
(Phospholipid tails are connected)
Branched fatty acid tails coming off of the tails
(Makes for a stronger membrane)
149
What are the limits of small cell?
more surface area per volume
150
What are the limits to large cell?
less surface area per volume
151
Why must cells have enough surface area?
to be able to obtain oxygen and nutrients and get rid of carbon dioxide and other waste products
152
Are eukaryotic cells compartmentalized?
yes
153
What does compartmentalization allow for in cells?
greater regulation over time and more efficient chemical reactions
154
Do plants have cholesterol?
no
155
What are the functions of cytoplasm?
cellular architecture, metabolic reactions
156
What are characteristics of the nucleus?
stores and organizes genetic information
Highly organized and compartmentalized
Membrane-bound organelle
157
What is nuclear lamina in the nucleus?
meshwork of filaments that regulate nuclear structure and gene expression
Helps nucleus have its proper architecture and regulating what goes on in and out of the nucleus
158
What does the nuclear pore complex allow for in the nucleus?
allows regulated exchange between the nucleus and cytoplasm
159
What is the nucleolus?
region within the nucleus where ribosomal RNAs are synthesized
160
What is chromatin?
DNA complexed with histone proteins
161
What is the nucleosome?
wrapped around core proteins, forming chromatin
162
What are ribosomes and their function?
complex of rRNA and protein
Cellular machinery used to synthesize proteins
163
What are mitochondrion?
membrane-bound organelles
Generates most of the chemical energy needed by all of the cellular biochemical reactions
Location of the synthesis of chemical energy in the cell
164
What is the peroxisome and its function?
contain enzymes used in oxidation reactions
Membrane-bound organelle
Break down fatty acids and amino acids
Location for detoxification
Not part of the endomembrane system
165
What is the vacuole?
structural support, storage, waste disposal, protection
A single vacuole in a plant cell can take up most of the space in the cell
166
What do all eukaryotic cells have?
Plasma membrane, cytoplasm, nucleus, ribosomes, mitochondria, peroxisomes, vacuoles
167
What do all animal cells have?
Centrosome (MTOC with centrioles), lysosomes
168
What do all plant cells have?
cell wall chloroplast, large central vacuole, some plant cells may contain centrosome and lysosomes
169
What do centrosomes form?
a microtubule organizing center (MTOC)
170
How many centrosomes do cells have?
2
171
Does a centrosome divide every time a cell divides?
yes
172
What is a lysosome?
contain hydrolytic enzymes
Recycles center of the cell because it breaks down nucleic acids, proteins, carbohydrates
Part of the endomembrane system
173
What kind of pumps do lysosomes contain?
proton pumps
Pumps H+s into the lysosome and lowers its pH
174
What is the plant cell wall?
rigid protective covering composed of cellulose (polysaccharide made of glucose)
Maintains turgor pressure developed by water in the vacuole
175
What are chloroplast?
membrane-bound organelle in plant cells
Site of photosynthesis
Synthesis glucose
176
What does the endomembrane system consist of?
endoplasmic reticulum, golgi apparatus, lysosomes, vacuoles and transport vesicles
177
What are cilia and what do they do?
numerous and smaller projections off of the cell
Prevents debris from entering the respiratory tract
178
What is the endomembrane system and what does it do?
group of membranes and organelles
Modify, package, and transport specific macromolecules
179
What are the 2 endoplasmic reticulums?
smooth and rough
180
What is in the endomembrane system?
smooth and rough endoplasmic reticulum, golgi apparatus, lysosomes
181
What are the characteristics of the smooth endoplasmic reticulum?
Lacks ribosomes
Carbohydrates, lipids, and steroid hormones are synthesized
Detoxification of medicines and poisons
Calcium ions are stored
182
What does the smooth endoplasmic reticulum specialize in and what does that do?
Specialized in muscle cells: sarcoplasmic reticulum
Stores large concentrations of calcium ions to allow coordinated muscle contraction
183
What are the characteristics of the rough endoplasmic reticulum?
Surface is studded with ribosomes
Location of protein synthesis for any protein that is secreted from the cell or embedded in the membrane
Proteins fold into 3d conformation
Modified by addition of carbohydrates
Phospholipids are synthesized here
Delivers proteins to golgi in membrane-bound vesicles
184
Is the golgi apparatus a part of the rough endoplasmic reticulum?
yes
185
What is the golgi apparatus?
series of flattened membranes
186
What are the 2 faces the golgi apparatus has?
cis and trans
187
What does the cis face of the golgi apparatus do?
receive proteins from RER
Faces nucleus
Sorts proteins based on function
Modifications: attaching carbohydrate chains, phosphate groups, other chemical groups
Modifications or specific amino acid sequences of the protein
Proteins will be sent out in membrane-bound vesicles on the trans face and directed to the proper cellular location
188
What does the trans face of the Golgi apparatus face?
faces the plasma membrane
189
What are the 3 types of cytoskeletal elements?
microtubule, microfilament, intermediate filament
190
What are microtubules and their function?
hollow tube formed from tubulin dimers
Job is to help chromosomes move through the cell
Attach to chromosomes
Resists compressive forces in the cell
191
What are microfilaments and what are their functions?
double helix of monomers made from actin
Structural role
Actin meshwork forms underneath membrane
192
What are intermediate filaments and what are their functions?
strong fiber of IF protein subunits like keratin
Structural role
Tapers nucleus in place in the cell
193
What do mitochondria, chloroplasts, and prokaryotes have in common?
size, shape, divide through binary fission, circular DNA, operons, antibiotic sensitive ribosomes, lipids
194
What is the endosymbiotic theory?
like mitochondria and chloroplasts within eukaryotic cells originated from free-living prokaryotic organisms that were engulfed by a host cell, eventually becoming integrated as organelles within the larger cell, essentially forming a symbiotic relationship where both organisms benefited from the arrangement
195
What organelles do animal cells have that plant cells don't have?
centrosomes and lysosomes
196
What organelles do plant cells have that animal cells don't have?
cell wall, chloroplasts, and a large central vacuole
197
What is a centrosome?
a cellular structure involved in the process of cell division
198
What is the extracellular matrix?
meshwork of proteins and carbohydrates that surrounds animal cells and provides structural support
199
What makes up the extracellular matrix?
Glycoproteins
Glycolipids
Cell membrane
Fibers of the ECM that attach to the components on the cell membrane
200
What is a major protein in the ECM?
collagen
201
What are collagen proteins modified with and what do they form?
carbohydrates
processed and secreted from the cell to form long fibers
202
What are the functions of collagen and what are they interwoven with?
The fibers give tissues strength and structural integrity
Interwoven with other proteins and carbohydrates
203
What do proteins in the ECM connect with and what are the functions of the proteins?
integral membrane proteins
help cells sense their environment and respond to the environment, detect chemical and mechanical signals coming through the ECM, trigger signalling pathways in response to the signals
204
What do ligands bind to and what does this cause?
cellular receptors to cause a cellular response
205
Do cells require constant intercellular communication?
yes
206
What makes up ligands? What is a cell surface receptor? What domain is on the extracellular side and what one is on the cytoplasmic side?
Transmembrane protein with an extracellular component and cytoplasmic component
Cell surface receptor: part of the protein is expressed at the surface of the cell
Has a ligand binding domain on extracellular side and an effector domain on the cytoplasmic side
207
What is a ligand? What does it secrete into? What does it bind to? What does it cause a change in when it binds to a receptor? What does this trigger?
any kind of signal that is sent between cells
Secretes into the extracellular matrix
Binds to the ligand binding domain
It causes a change in the effector domain
Conformational change that triggers signalling downstream
208
What are the 4 types of chemical signaling in multicellular organisms?
Autocrine (cell signals to itself)
-Cell synthesizes signal and responds to signal
Direct signaling across gap junctions
-Direct in between two cells in gap junctions
Paracrine (cell signals other nearby cells)
Endocrine (cell signals over long distances)
209
What is an example of an autocrine?
nucleus contains the genome of the cell and makes an mRNA molecule, a ligand is secreted and is synthesized in ER, processed in the golgi, packed into vesicles, and the ligand is secreted from the cell in the vesicle, the ligand binds to a cell surface receptor on the same cell and triggers some kind of change in the cell
210
What do adjacent cells communicate directly through?
plasma membrane junctions
211
What are tight junctions and what is their function?
seals cells together
Has proteins that hold them closed
Created a water-tight seal in between two cells
Prevent the passage of fluids or other types of substances from crossing the cells
Particularly high in concentration and high in density in tissues that need to contain fluids (bladder, kidneys, intestines)
212
What are desmosomes and what are their functions?
connects the cytoskeletons of cells
doesn't allow the for passage of materials between two cells but is important for structural support
Serve as mechanical stress signals
213
What are gap junctions and what are their functions?
channels between cells
Allow for transport of ions, water, and other substances
Can transmit electrochemical signals between cells
Important in cardiac muscle
Electric signal for the heart to contract spreads rapidly
214
What is direct signaling?
Cells that are directly next to each other can communicate through surface proteins
215
What is cadherin and what does it do?
protein that helps cells stick together
Between cells of the same tissue
Can help cells stick to surface
Keeps everything in place
216
What is synaptic signaling?
specialized kind of paracrine signaling between presynaptic cell and postsynaptic cell (neurosynapsis) through a short distance
217
What happens when a neuron releases a neurotransmitter? What does the neurotransmitter do and what does it bind to? What destroys the neurotransmitter?
The end of the neuron releases a neurotransmitter, the neuron gets a signal that causes the neurotransmitter to be released into the neurosynapsis
Neurotransmitter carries the signal and binds to receptors on the postsynaptic cell and causes a change
There is an enzyme that can destroy the neurotransmitter because the pulses of information needs to be rapid and recover for the next signal to come along
218
Where are hormones synthesized?
Hormones are synthesized and secreted into the circulatory system
219
Where does thyroid signaling start and where does it secrete a signal to? What does the thyroid gland do to the hormone?
starts in the hypothalamus, secretes a signal to the pituitary gland, signals to the thyroid gland, the thyroid gland releases the hormone
220
What are thyroid hormones involved in?
metabolism and growth
221
What is a g protein-coupled receptor?
One of the most common types of cellular receptors receiving extracellular signals
Transmembrane protein
222
What do g proteins bind to?
binds to receptors and works together to receive and communicate signals
223
What happens when a ligand binds to a g protein-coupled receptor?
triggers changes in the g protein and leads to signal transduction
The signal is getting passed into the cell to cause certain changes
224
What is an example of a g protein-coupled receptor?
epinephrine
225
What happens to the receptor when epinephrine binds to it?
receptor changes shape and triggers the g protein to trade its gdp for gtp
226
Is the receptor on or off when it is bound to gdp?
off
227
Is the receptor on or off when it is bound to gtp?
on
228
What does the g protein do when it is activated?
it separates into different components
229
What are the subunits of the g protein?
Alpha, beta, and gamma subunits
230
What does the alpha subunit of the g protein do and what does it interact with?
moves down the membrane away from the epinephrine receptor and interacts with an enzyme called adenylyl cyclase
231
What happens to the adenylyl cyclase when the alpha subunit interacts with it?
converts ATP to cyclic AMP
232
What is cyclic AMP and what does it bind to and what does this do? What enzyme does it bind to?
Second messenger
Binds to protein kinase A and activates it
Activates phosphorylase kinase and leads to activation of an enzyme called glycogen phosphorylase (allows for glycogen to break up into glucose monomers and release into the bloodstream)
233
What does cell signaling trigger?
cell growth, division, and cell migration
234
What does the bladder have to prevent fluids from leaking out?
tight junctions
235
What are glycoproteins and glycolipids involved in?
cell-to-cell adhesion
236
What are the proteins involved in adjacent cell communication through surface proteins?
cadherin: maintains the structural integrity of tissues and organs
selectin: proteins that help white blood cells attach to other cells
integrin: proteins that help cells attach to other cells and to the extracellular matrix (ECM)
237
What is an example of an endocrine?
frog metamorphosis, development of the tail and lungs is driven through thyroid signaling
238
What is the structure of thyroid hormones and what does this allow?
Thyroid hormones have a hydrocarbon ring structure that allows them to be stable as they travel through the bloodstream to their target cell
239
What does it mean when a g protein is heterotrimeric?
the g protein is made of 3 different subunits
240
What does it mean when the subunits of a g protein are molecule-switched?
because they can bind to gtp to turn on, remove a phosphate group, and get released as gdp to turn off
241
How does adenylyl circularize ATP?
Cuts off the phosphate group and forms a bond with the sugar to make it circularized
242
What kind of signaling molecule is cAMP?
internal
