Chapter 5 Flashcards
1
Q
In what way do the membranes of eukaryotic cells vary?
A
certain proteins are unique of the membrane of each cell type
2
Q
Which of the following pairs correctly matches a membrane transport process to its primary function?
A
pinocytosis; the uptake of water and small solutes into the cell by formation of vesicles at the plasma membrane
3
Q
What event would activate a G protein?
A
replacement of GDP with GTP
4
Q
Which of the following correctly describes a general property of all electrogenic pumps?
A
they create a voltage difference across a membrane
5
Q
The fluid aspect of the membrane is due to the lateral and rotational movement of phospholipids, and embedded proteins account for the mosaic aspect
A
The plasma membrane is referred to as “fluid mosaic” structure. Which of the following statements about the model is true?
6
Q
Which of the following molecules is most likely to passively diffuse across the plasma membrane?
A
carbon dioxide
7
Q
Second messengers tend to be water-soluble and small. This accounts for their ability to
A
rapidly move throughout the cell by diffusion
8
Q
The concentration of solutes in a particular cell is about 2%, but the cell contains almost no sucrose or urea. Sucrose cannot pass through the membrane of its cell, but water and urea can. Osmosis would cause this cell to shrink the most when immersed in which of the following solutions?
A
a hypertonic sucrose solution
9
Q
Receptors for signal molecules
A
may be found embedded in the plasma membrane or found within the cytoplasm or nucleus
10
Q
Which of the following statements about passive transport is correct?
A
Passive transport involves movement of solute in both directions across a membrane, but the net movement of solute is DOWN its concentration gradient
11
Q
The general name for an enzyme that transfer phosphate groups from ATP to a protein is
A
protein kinase
12
Q
Testosterone, a lipid-soluble signaling molecule, crosses the membranes of cells throughout the body but affects only target cells because
A
intracellular receptors for testosterone are present only in target cells
13
Q
Nitric oxide is unusual among animal signal molecules in that it __________.
A
is a gas
14
Q
Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because __________.
A
they amplify the original signal
15
Q
Consider the currently accepted fluid mosaic model of the plasma membrane. Where in the plasma membrane would cholesterol most likely be found?
A
In the interior of the membrane
16
Q
Which of the following statements concerning carbohydrates associated with the plasma membrane is correct?
A
Membrane carbohydrates have a primary role in cell-cell recognition.
17
Q
Which of the following processes and organelle(s) account for the replacement of lipids and proteins lost from the plasma membrane?
A
Exocytosis and smooth and rough ER
18
Q
The molecule cAMP directly activates __________.
A
protein kinase A
19
Q
Which of the following would be least likely to pass through a plasma membrane without the help of a transport protein?
A
A large polar molecule
20
Q
Which of these statements describes some aspect of facilitated diffusion?
A
It may occur through transport proteins in the membrane.
21
Q
Which of the following would tend to increase membrane fluidity?
A
A greater proportion of phospholipids with unsaturated hydrocarbon tails
22
Q
the surface measurements of that cell membrane and cell membrane determines what goes on in and out of the cell
A
Surface Area Determines
23
Q
All living things have a…
A
cell membrane
24
Q
In phospholipids, the head is and the tail is
A
in phospholipids, the head is polar and the tail is nonpolar
25
Cholesterol can keep phospholipids from becoming...
too packed when temperatures drop or too fluid in warm temps
26
-can go through the cell membrane
-transport different materials
-make glucose from your food make it to cells to form ATP
Integral Proteins
27
-act as enzymes to speed up reactions
-attach to cytoskeleton structures to help with cell shape
Peripheral Proteins
28
Glycolipid
carbohydrates bonded to a lipid
29
Eukaryotes are...
membrane bound organelles
30
Examples of molecules that can cross or enter the phospholipid bilayer
oxygen and carbon dioxide
31
Simple Diffusion
molecules that can cross or enter the phospholipid bilayer without the help of a transport protein
32
Passive Transport
takes no energy to move molecules in or out of the cell
33
Facilitated Diffusion
when molecules can't cross the cell membrane on their own or molecules that are polar and need help of transport protein
34
Active Transport
pushing of molecules to go against their concentration gradient
35
3 Types of Endocytosis
phagocytosis
receptor-mediated endocytosis
pinocytosis
36
Endocytosis
fusing of substances with the cell membrane to form vesicles
37
Plasma membrane in cells is
selectively permeable
38
Diffusion
form of passive transport that does not require energy from the cell
39
Osmosis
diffusion of water across a membrane
40
Sodium Potassium Pump
moves ions against their concentration gradient
41
Co-Transport
sodium ions and glucose move into the cell through a cotransporter protein
42
Non-steroid hormones
those derived from amino acids
43
Examples of non-steroid hormones
oxytocin
epinephrine
44
Anterior Pituitary Gland
produces six different kinds of hormones
45
Growth Hormone
lack of it results in dwarfism
excess of it results in gigantism
46
Adrenocorticotripic Hormone
targets the adrenal cortex
47
Tyroid Stimulating Hormone
raises T3 and T4 levels
48
Follicle Stimulating Hormone
development of eggs and sperm
49
Lutenizing Hormone
stimulates hormone production by ovaries and testes
50
Prolactin
stimulates milk production
51
Antidiuretic Hormone
promotes water retention by kidneys, stores and releases oxytocin
52
Oxytocin
stimulates contraction of uterus and mammary gland cells
53
Hypothalamus
controls the pituitary gland and produces/ releases inhibiting hormones
54
Pineal Gland
produces melatonin
55
Thyroid/ Parathyroid Gland
located at the base of neck and produces thyroxine (T4) and Calcitocin
56
Thyroxine
stimulates and maintains metabolic processes and plays a role in development
57
Calcitocin
opposes action of parathyroid hormone
58
Parathyroid
produces parathyroid hormone which raises blood calcium levels
59
Thymus
produces thymosin and stimulates the development of immune cells
60
Adrenal Medulla
creates epinephrine and nonepinephrine which triggers fight or flight
61
Adrenal Cortex
glucocorticoids, mineralocorticoids
62
Pancreas
produces insulin and glucagon which raise and lower blood glucose levels
63
Ovaries
produce estrogen and progesterone; helps to promote growth of the lining of the uterus
64
Estrogens
the hormones that promote the development of female secondary sex characteristics
65
Testes
produce androgens which are the main male hormones
66
Fluid bilayer is composed of
phospholipids
67
Amphipathic means
something is both hydrophobic and hydrophilic
68
Do phospholipids w/saturated fatty acids contain double bonds in their tails?
no
69
How do phospholipids w/saturated fatty acids in the plasma membrane effect membrane fluidity?
the saturated fats decrease fluidity in the plasma membrane
70
Do phospholipids w/unsaturated fatty acids contain double bonds in their tails?
yes
71
How do phospholipids w/unsaturated fatty acids in the plasma membrane effect membrane fluidity?
the unsaturated fats increase fluidity in the plasma membrane
72
How does the presence of cholesterol ( at moderate temp) affect membrane fluidity?
cholesterol decrease fluidity in the plasma membrane
73
How does the presence of cholesterol ( at low temp) affect membrane fluidity?
cholesterol increases fluidity in the plasma membrane
74
True or False: Thermophilic bacteria that live in hot springs have many phospholipids with unsaturated fatty acids in their plasma membrane, that help increase membrane fluidity
false
75
What does this image depict in its entirety?
Phospholipid Membrane
76
Phospholipid Membrane Description
hydrophobic tails that face each other ( sheltered from water) and hydrophilic heads exposed to water
77
What does this image depict?
glycoprotein
78
Glycoprotein Description
integral ( transmembrane) protein embedded in membrane with attached carbohydrate
79
Peripheral Protein Description
protein that is loosely bound to the surface of membrane
80
This image depicts...
a channel protein
81
Channel Protein Description
integral (transmembrane) protein embedded in membrane that can transport substances in/out of cell
82
Glycolipid Description
phospholipid with attached carbohydrate
83
Cholesterol Description
steroid found in plasma membrane of animal cells
84
Name Parts A-H
a: phospholipid
b:glycolipid
c:glycoprotein
d: carbohydrate
e: cholesterol
f: ?
g: channel protein
h: phospholipid membrane
85
True or False: Peripheral Proteins are composed of nonpolar amino acids
false
86
True or False: Transmembrane proteins are composed of nonpolar & polar amino acids
true
87
What type of molecule can easily cross the phospholipid bilayer?
small non-polar
88
Examples of molecules that can cross the phospholipid bilayer
O2, CO2, steroids
89
Only certain molecules can pass through the phospholipid bilayer, exhibiting
selective permeability
90
What type of molecule can slowly pass through the membrane?
small, uncharged and polar molecules
91
What type of molecule cannot pass through the membrane
large, polar molecules
92
Examples of molecules that can slowly pass through the membrane
H2O, ethanol
93
Examples of molecules that can't pass through the membrane
sugars, ATP, ions
94
True or False: Transport proteins must be used by molecules that cannot pass the phospholipid bilayer on their own
true
95
True or False: although water can pass through the membrane on its own, large amounts of water cross the membrane using aquaporin transport proteins
true
96
Simple Diffusion:
1) because these are Co2 molecules
2) because the molecules are able to cross the bilayer without the help of a transport protein
97
Facilitated Diffusion:
the molecules are using the help of transport proteins to get them across the cell membrane
98
Two types of facilitated diffusion proteins
carrier proteins
channel proteins
99
Carrier proteins
bind specific molecules to be transported one one side of the membrane
100
Carrier Protein
101
Channel Protein
102
Osmosis
facilitated diffusion of water across a membrane
103
Process of Osmosis
the solvent ( water) follows the solute, moving in the direction of higher solute concentration
104
Tonicity
the ability of a solution to cause a cell to gain or lose water
105
Hypotonic
amount of solute in the solution is LESS than the amount of solute in the cell
106
Isotonic
amount of solute in the solution is EQUAL TO the amount of solute in the cell
107
Hypertonic
amount of solute in the solution is GREATER than the amount of solute in the cell
108
In Hypotonic solutions, water has a net movement .....
in
109
In Isotonic solutions, water has a net movement
neither in nor out
110
In hypertonic solutions, water has a net movement
out
111
True or False: Plant and animal cells prefer an environment that is isotonic
false
112
True or False: a hypotonic solution is ideal for a plant cells because of rigidity of the plant cell wall which prevents bursting
true
113
In active transport, ions move from
low concentration to high concentration
114
Electrochemical gradient
drives ion diffusion across membrane-effect of membrane potential + ion's concentration gradient
115
Electrogenic Pumps
transport protein that generates volatage across the membrane
116
Cell Signaling
an event when one cells sends a chemical signal to which another cell responds
117
True or False: mechanisms of signaling are often very different across different groups of unicellular and multicellular organisms
false
118
True or False: in some multicellular organisms, communication allows trillions of cells of body to coordinate their activities
true
119
Types of Cell Junctions
animal cells: gap junctions
plant cells: plasmodesmata
120
gap junction found in ANIMAL CELLS
121
plasmodesmata
122
Cell Recognition
membrane bound cell-surface molecules
123
Paracrine
a cell produces a signal molecules that only influences cells near it in the same tissue
124
Synaptic Signaling
-electrical signal triggers release of nuerotransmitter
-neurotransmitter diffuses across synpase
125
Reception
First messenger epinephrine binds to GPCR, activating it
126
Transduction step 1
GPCR binds to G-protein
GDP is converted to GTP, activating it
127
Transduction step 2
activated G protein binds to adenyl cyclase
128
Transduction step 3
activated adenylyl cyclase converts to ATP to the second messenger Cyclic AMP
129
Transduction step 4
cAMP activates protein kinase and other molecules in a phosphorylation cascade
130
Response
breakdown of glycogen and rise of blood sugar molecules
131
Which of the following molecules can cross the lipid bilayer of a membrane directly, without a transport protein or other mechanism? Select all that apply.
lipids
carbon dioxide
water
oxygen
132
Only Channels
-provide a continuous path across the membrane
-allow water molecules and small ions to flow quickly across the membrane
-are integral membrane proteins
133
Only Carriers
-undergo a change in shape to transport solutes across the membrane
-transport primarily small polar organic molecules
134
Both Channels and Carriers
-transport solutes down a concentration or electrochemical gradient
-provide a hydrophilic path across the membrane
135
Which of the following statements about the conditions shown in the U-shaped tube are true?
-water is tightly clustered around the hydrophilic solute molecules on both sides of the membrane
-there is less free water in the right arm of the tube than in the left arm of the tube
136
During osmosis, water diffuses across a selectively permeable membrane from the region of higher ( blank) concentration and lower ( blank) concentration to the side with lower ( blank) concentration and higher ( blank) concentration
During osmosis, water diffuses across a selectively permeable membrane from the region of higher free water concentration and lower solute concentration to the side with lower free water concentration and higher solute concentration
137
If more water were added to the solution on the left side of the tube, what would happen to the water level on the right side of the tube?
the water level would go down
138
If the pores in the selectively permeable membrane became larger, but still not large enough to let the sugar pass through, what would happen during osmosis in the U-shaped tube compared to what is shown in the figure?
The final water levels would be the same as shown in the figure, but the solutions would reach near equal concentrations faster.
139
because membranes are fluid, membrane proteins and phospholipids can drift about in the membrane
the diverse proteins found in and attached to membranes perform many important functions
The framework of a membrane is a bilayer of phospholipids with their hydrophilic heads facing the aqueous environment inside and outside of the cell and their hydrophobic tails clustered in the center.
Which statements about the fluid mosaic structure of a membrane are correct? Select the three correct statements.
140
In this diagram of the plasma membranes of two adjoining cells, identify the protein indicated by the white arrow, including its function.
a receptor protein that binds with a signaling molecule and relays the message into the cell by activating other molecules inside the cell
141
You are working on a team that is designing a new drug. For this drug to work, it must enter the cytoplasm of specific target cells.
Which of the following would be a factor that determines whether the molecule selectively enters the target cells?
the similarity of the drug molecule to other molecules that are transported into the target cells
142
Which of these glands secretes releasing hormones?
hypothalamus
143
Which of these hormones are responsible for the "fight or flight" response to danger?
epinephrine and norepinephrine
144
Adrenocorticotropic hormone (ACTH) triggers the release of _____ in response to stress.
glucocorticoids
145
_____ are the main male hormones.
androgens
146
What hormone promotes water retention by the kidneys?
antidiuretic hormone (ADH)
147
Which hormone opposes the action of parathyroid hormone?
calcitonin
148
Which hormone stimulates hormone production by the ovaries and testes?
luteinizing hormone (LH)
149
Which hormone stimulates milk production?
prolactin
150
Receptors for nonsteroid hormones are located in _____.
association with a cell's plasma membrane
151
Which of these is a nonsteroid hormone?
epinephrine and oxytocin
152
How do nonsteroid hormones differ from steroid hormones?
nonsteroid hormones act via signal transduction pathways; steroid hormones do not act via signal transduction pathways
153
Select all of the correct statements about transcription factors.
Transcription factors can switch genes off.
Transcription factors can switch genes on
154
A human cell placed into a hypertonic solution is likely to
lose water by osmosis
155
Phospholipids vary in the small molecules attached to the phosphate group. The phospholipid shown in the figure has a ( blank) attached to phosphate
Choline group
156
Because the phosphate group and its attachments are either charged or polar, the phospholipid head is ( blank) which means it has an affinity for water
Hydrophilic
157
A phospholipid also has two “tails” made up of two (blank) molecules, which consist of a carbonyl group with a long hydrocarbon chain attached
Fatty acid
158
Because the c-h bonds in the fatty acid tails are relatively nonpolar, the phospholipid tails are (blank) which means they are excluded from water
Hydrophobic
159
When a person is dehydrated, his or her IV fluids
should be isotonic, because either a hypertonic or hypotonic IV would damage red blood cells.
160
If you are going to bake potatoes, and your potatoes are soft and dehydrated, they can be soaked in __________ to make them more firm before baking.
a hypotonic solution such as tap water
161
A human cell placed in a hypotonic environment would
take up water through osmosis.
162
A cell that neither gains nor loses water while sitting in a solution is probably sitting in
an isotonic environment.
163
Paramecium is a genus of protists that lives in water. It has organelles called contractile vacuoles that continually eliminate the excess water gained through osmosis. Knowing that Paramecia gain water through osmosis, we can deduce that they normally live in
freshwater lakes and ponds
164
Many bacteria and fungi have a difficult time surviving on our food if the food is very salty. The best explanation for this is
that the salt in the food creates a hypertonic environment for the bacteria and fungi.
165
A signal transduction pathway is initiated when a _____ binds to a receptor.
signal molecule
166
A signal molecule is also known as a(n) _____.
ligand
167
Which of these is the second of the three stages of cell signaling?
transduction
168
Which of the following statements correctly describe(s) the driving forces for diffusion of Na+ and K+ ions through their respective channels? Select all that apply.
-The diffusion of Na+ ions into the cell is facilitated by the Na+ concentration gradient across the plasma membrane.
-The diffusion of K+ ions out of the cell is impeded by the electrical gradient across the plasma membrane.
-The electrochemical gradient is larger for Na+ than for K+.
169
Which of these extracellular signal molecules could diffuse through a plasma membrane and bind to an intracellular receptor?
oxytocin
170
The primary reason steroid hormones usually act slowly is that _____.
they turn genes on or off and it takes time for gene products to build up or become depleted
171
Steroid hormone-receptor complexes act in _____.
the nucleus
