Chap 3 Flashcards
1
Q
Cells
A
Structural units of all living things
2
Q
Amount of cells in the body
A
50-100 trillion
3
Q
Explain the principle of complementarity of cells
A
Activities of cells are dictated by their shapes and by the types and numbers of subcellular structures they contain
4
Q
Cells arise from
A
Other cells. Most body cells from mitosis,
Sex cells come from meiosis
5
Q
What underlies every disease?
A
The loss of homeostasis in cells
6
Q
Examples of the shape of cells
A
Disc shaped red blood cells, branching nerve cells, cube shaped cells of kidney tubules
7
Q
Which cells connect body parts, form linings to transport gases?
A
Epithelial cells,
Fibroblasts,
erythrocytes
8
Q
Which cells move organs and body parts?
A
Skeletal and smooth muscle cells
9
Q
Which cells stores nutrients
A
Fat cell
10
Q
Cells that fight disease
A
Macrophage
11
Q
Cell that gathers information and controls body function
A
Nerve cells
12
Q
Cell of reproduction
A
Sperm and eggs
13
Q
Three main parts of a generalized cell
A
Plasma membrane
Cytoplasm
Nucleus
14
Q
Plasma membrane
A
Outer boundary of a cell, acts as selectively permeable barrier
15
Q
Cytoplasm
A
Intracellular fluid packed with organelles,
16
Q
Organelles
A
Small structures that perform specific functions
17
Q
Nucleus
A
Organelle that controls cellular activities
18
Q
Extracellular materials
A
Substances contributing to body mass that are outside of the cells
19
Q
Types of extracellular materials
A
Extracellular fluid
Cellular secretions
Extracellular matrix
20
Q
Extracellular fluid includes
A
Interstitial fluid,
Blood plasma
Cerebrospinal fluid
21
Q
Interstitial fluid
A
Body fluid filling the space surrounding cells, lymphatic capillaries and vascular
22
Q
Function of ECF
A
Dissolves and transports substances in the body
Has amino acids, sugars, fatty acids, regulatory substances and wastes. Each cell extracts what it needs from the ECF
23
Q
Cellular secretions
A
Aid in digestion
(Intestinal and gastric fluids)
Some act as lubricants (saliva, mucus, serous fluids)
24
Q
Extracellular matrix
A
Most abundant extracellular material.
Jelly-like has proteins and polysaccharides.
25
Extracellular matrix function
Helps bind cells, most abundant in connective tissues
26
Plasma membrane
Phospholipids, cholesterol and proteins.. selectively permeable
27
What does the plasma membrane separate?
The extracellular fluid from the intracellular fluid
28
Fluid mosaic model thickness
7-10 nm
29
Fluid mosaic model
Proteins and cholesterol dispersed in the plasma membrane. Constantly changing.
30
Lipids in plasma membrane
Phospholipids
Cholesterol
31
Cholesterol functions in membrane
-Stiffens membrane
-decreases water solubility of membrane
-4 ring structure
32
Phospholipids functions
-Make basic structure of membrane
-Hydrophobic tails prevent water soluble elements from crossing
33
Proteins
-Determines which roles the membrane can do
-Transport, communication, receptors, attachment
different shapes have -different functions
34
Carbohydrates function in plasma membrane
-identify cells so they can sort themselves
-on outer surface of membrane. Like sugar covering a breakfast cereal
35
Glycocalyx
Covering of carbs on outer surface of cell membrane
36
Movement of phospholipids
Can move side to side but rarely flip over
37
Mobility of cholesterol
Can move easily to the other layer
38
Lipid anchor attaches to
Protein
39
Integral proteins
Embedded in lipid bilayer
40
Peripheral proteins
Anchored to membrane or to other proteins but not embedded in membrane
41
Glycoproteins
Carbs attached to proteins
42
Glycolypids
Carbs attached to lipids
43
Types of passive transport across plasma membrane
1. Simple diffusion
2.Facilitated diffusion
3. Osmosis
4. Filtration? Happens through capillary walls
44
Diffusion
Moving from high concentration to low concentration no energy. Try to make dispersion even
Depends on size and charge
45
Concentration gradient
Moving from high concentration to low concentration
46
Driving force for diffusion
Kinetic energy of molecules. Constant random high speed motion of molecules and ions. The molecules and ions clash into each other and push each other to help scatter particles
47
What affects speed of diffusion?
Concentration
Molecular size
Temperature
48
Explain how Concentration affects diffusion
When there's a large concentration of molecules in one area, those in the concentrated area are more likely to collide. The collisions push them away
49
How does molecular size affect the rate of diffusion?
Smaller molecules diffuse more rapidly
50
Temperature
Higher temperature increases kinetic energy and causes the molecules to interact more rapidly, causing more diffusion to happen
51
When has a container reached equilibrium?
When the molecules are spread evenly throughout. No net movement molecules move evenly in all directions
52
Distance molecules travel during diffusion?
1/1000 of a page's width
53
Examples of diffusion
Ions across cell membranes
Neurotransmitters between 2 nerve cells
54
What feature of the plasma membrane lets it be selectively permeable?
The hydrophobic core
55
Why is the selective permeability of a cell membrane important?
Let's nutrients go in but keeps bad substances out.
Keeps important proteins in but let's wastes go out
56
Facilitated diffusion
Moving with the help of transport proteins down the concentration gradient
57
Example of facilitated diffusion?
Water passing through aquaporins
58
Na K moves through or against concentration gradient?
Against
59
Active transport
Move using energy through membrane
60
Explain how NaK pump works?
Energy from ATP is used to move 3 Na ions out of cell and 2 K ions into cell.
61
Primary active transport
Uses ATP directly
62
Secondary active transport
Move chemicals against gradients using energy but doesn't use ATP. I stead it uses downhill gradient from ion or molecule . Uses downhill gradient from one ion or molecule to drive uphill movement of another substance
63
Example of secondary active transport
Na & glucose into cell using cotransport ir symport.
Na ions move down gradient, glucose moves against concentration gradient
64
Exocytosis
Cells move substances from the intracellular fluid to the extracellular fluid using vesicles
65
Endocytosis
Membrane pinches in to create a vesicle
66
Ways to move materials across membranes
Active transport
Passive transport
Exocytosis
Endocytosis
67
Active process
Cell uses energy to move solutes across membranes
68
When are active processes used?
Substances too large, insoluble in lipids,
Move against concentration gradient
69
Types of active membrane transport
Active transport and vesicular transport
70
Difference between active transport and facilitated diffusion
Active transport Transports specific substances in reverse direction, needs energy
Facilitated diffusion always follows concentration gradients because it uses kinetic energy
71
Where does the energy in primary active transport come from?
Hydrolysis of ATP which powers pumps (transport proteins)
72
Secondary active transport energy source
Concentration gradients of ions made by primary active transport pumps. Always move more than one substance and use cotransport protein
73
Similarities between types of active transport
Primary and secondary active transport both transport specific substances
No transporter no transport
74
Explain primary active transport
1. ATP gets hydrolysed and a Phosphate comes off
2. Phosphate binds to the transport protein and gives it energy
3. Transport protein changes shape and pumps bound solute across membrane
75
Examples of primary active transport systems
Calcium and hydrogen pumps
NaK pump
76
What is the pump protein for the sodium potassium pump?
Na+ -K+ ATPase
77
Explain the movement that happens thanks to the Na K pump
For every one ATP broken
Three Na+ go out of cell and two K+ go back in
78
Concentration of K+ in the cell is....
10x higher than outside, reverse is true of Na
79
Why is the difference in concentration in Na K important?
Let muscle cells and nerve cells function normally.
Let cells maintain fluid volume.
80
How does the Na K pump almost function continuously?
Na+ and K+ leak slowly but continuously through leakage channels down their concentration gradient, the Na+ -K+ pump operates almost continuously
81
Electrochemical gradients
Affect the way ions diffuse
82
Explain secondary active transport
The pump stores energy by moving Na against it's concentration gradient. Then like water held back by a dam, it can do work as it flows down. A substance moved across a membrane can do work as it leaks back. It drags substances back down
83
Symport system
2 substances move in same direction
84
Antiport system
2 substances move in opposite directions.
85
Example of antiport system
Cotransporter used to regulate pH of cells
86
Vesicular transport
Fluids containing large particles are transported via membranous sacs
87
Transcytosis
Moves substances into, across then out of the cell.
88
Where does transcytosis happen?
Endothelial cells lining blood vessels. Gets substances from blood into interstitial fluid
89
Vesicular trafficking
Moves substances from one area or organelle to another part of the cell.
90
What gives energy for vesicular transport?
ATP of Guanosine triphosphate
91
How do receptors help endocytosis?
Receptors in membrane help determine substances to be transported
92
Coated pit
Infolding of membrane. How vesicle starts to form. Coated with proteins
93
Explain the steps of vesicular transport
1. Coated pit ingests substance
2. Protein coated vesicle detaches
3. Coat proteins are recycled to plasma membrane
4. Uncoated vesicle fuses with a sorting vesicle called an endosome
5. Transport vesicle containing membrane components moves to the plasma membrane for recycling.
6. Fused vesicle may fuse with a lysosome to destroy contents or deliver it's contents to the plasma membrane on the opposite side of the cell
94
Three types of endocytosis
1.Phagocytosis
2.Pinocytosis
3. Receptor mediated endocytosis
95
Phagocytosis process
Cell eating
1. Cell engulfs large or solid material
2. Particle binds to surface receptors, pseudopods form around the particle (phagosome)
3. Phagosome fuses with lysosome and contents are digested
96
Phagocytes
WBCs that "eat" substances and destroy harmful materials
97
Phagocytes move using _____ motion
Amoeboid
98
Amoeboid motion
Changing shape
Flowing movement of cytoplasm to move across a surface
99
Pinocytosis explain
"cell drinking"
Membranes folds around ECF with dissolved molecules
100
Does pinocytosis happen in most cells?
Yes, nonselective way of sampling ECF
101
In which cells is pinocytosis most important?
In cells that absorb substances like those in the intestines
102
Explain why the area of the cell membrane remains constant?
Parts of membrane that make vesicles are recycled immediately using exocytosis after use
103
Receptor mediated endocytosis
Lets specific things go in through endocytosis and transcytosis
1. Receptors bind to substances and are taken in then dealt with
104
Which substances are taken in through receptor mediated endocytosis
Enzymes, insulin, low density lipoproteins and iron
105
What can hijack receptor mediated endocytosis?
Diphtheria
Flu viruses
Cholera
106
Phagosome
Membranous sac made by plasma membrane
107
Exocytosis caused by
Cell surface signals (a hormone binds)
Change in membrane voltage
108
Uses of exocytosis
Hormone secretion
Neurotransmitter release
Mucus secretion
Ejection of wastes
109
Secretory vesicle
Membranous sac that is protein coated, moves to cell membrane, fuses the ruptures
110
Explain the process of exocytosis
1. Membrane bound vesicle migrates to plasma membrane
2.proteins at vesicle's (v and t snares) surface bind
3. Vesicle and plasma membrane fuse and a pore opens up
4. Vesicle contents are released to the cell's exterior
111
Explain docking of exocytosis
V-snares for vesicle recognize t-snares for target. Membranes corkscrew and fuse together, rearrange the lipid monolayers without fusing them
112
Example of receptor mediated endocytosis
Intake or hormones, cholesterol, iron, most macromolecules
113
Example of vesicular trafficking
Intracellular trafficking between certain organelles, endoplasmic reticulum, golgi apparatus
114
Exocytosis examples
Secretion of neurotransmitters, hormones, mucus
115
Permeability
The ability of molecules and ions to pass through a membrane
116
Membrane potential
Voltage across a plasma membrane
117
In which cells is membrane potential most important?
Nerve and muscle cells
118
Voltage
Electrical potential energy resulting from the separation of oppositely charged particles. In cells oppositely charged particles are ions and what separates them is the plasma membrane
119
Resting membrane potential + range
Voltage that exists across membrane during resting state of excitable cell
-50 to -90 mV
120
Why are cells considered electrically polarized?
because even at resting state all cells have a charge that ranges from -50mV to -90mV
121
The minus sign of a cell's voltage indicates what?
inside of cell is negative compared to its outside
122
voltage
charge separation
123
where does differences of charges only occur?
At the membrane
124
Describe the charges in the cytoplasm?
Charges in the cytoplasm are electrically neutral . they add up and cancel eachother out. Same with the ECF
125
permeability
ability of ions and molecules to pass through a membrane
126
Osmosis
diffusion through selectively permeable membrane by a solvent
127
Why does the resting membrane potential exist?
diffusion causes ionic imbalances that polarize the membrane. active transport maintains the membrane potential.
128
which concentration gradient mostly determines membrane potential?
concentration of K+ and the permeability of K+ to the membrane
129
which anions predominate inside of body cells?
K+ and protein anions
130
Extracellular fluid contains more of which ion?
Na+ balanced by Cl-
131
The plasma membrane is somewhat permeable to K + but impearmeable to
protein anions.
132
why is the cytoplasmic side of the membrane more negative?
k+ can diffuse out following its concentration gradient but the protein anions can't and so their negative charges stay inside.
133
Explain the steps of generating the resting membrane potential
K+ diffuses down the steep concentration gradient (out of the cell) via leakage channels, causing a negative charge on the inner face of the plasma membrane.
2. K+ also moves back into cell because its attracted to the negative charge on the inner plasma membrane.
3. A negative membrane potential (voltage) is created when the amount of K+ going out of cell equals the amount of K+ going into the cell. exiting K+ gradient directly opposes the gradient for K+ entry
134
Why is membrane potantial largely determined by K+?
At rest, the membrane is much more permeable to K+ than Na+. The active transport of Na and K ions by the Na+ K+ pump maintains the concentration gradients
135
In many cells, Na+ also contributes to resting membrane potential. Its resting membrane potential usually is -70 mV , but why is K more influential?
K+ diffuses through the membrane much more easier.
136
Do you need a lot of ions to generate membrane potential?
no. the number of ions is small and does not change the concentrations in any way.
137
In cells at rest, how many ions cross plasma membrane?
Very few. There is some net movement of K+ out of the cell and Na+ into the cell. Na+ is very strongly pulled in because of the concentration gradient and interior negative charge.
138
How does active transport help maintain the membrane potential?
rate of active transport must be equal to the rate of diffusion of Na+ diffusion into the cell. If more Na+enters, more is pumped out. The pump maintains the membrane potential and the osmotic gradient. If too much Na+ stayed in the cell and wasn't removed, the water would go in and the cells would burst.
139
electrochemical gradient
The diffusion of particles happens because of differences in concentrations and because of electrical charges.
140
Give an example of how the electrochemical gradient works?
the diffusion of K+ is helped by the concentration gradient but it is opposed by the electrical charges. the electrical charges pull it in but the concentration pushes it out.
The negative charges on the inner part of the cell membrane pull Na in but the impermeability limits Na diffusion
141
What activates cells to carry out homeostatic functions
respond to extracellular chemicals, hormones, neurotransmitters, some cells interact with others
Extracellular molecules
142
What percentage of membrane lipid is cholesterol?
20%
143
144
Polar region of cholesterol
Hydroxyl group
145
Non polar region of cholesterol
Fused ring system
146
Makes up halo the plasma membrane by mass and preforms most functions
Proteins
147
Types of proteins on cell membrane
1.Transport
2.Receptors
3.Enzymes
4.cell-cell recognition (glycoproteins act as identity tags)
5. Attachment to cytoskeleton and ECM(extracellular matrix)
6. Cell to cell joining
148
Transmembrane proteins
Go through membrane and peek out on both sides
149
Types of transmembrane proteins
Channels, pores
Carriers,
Enzymes,
Receptors
150
Protein pores
Opening of duct or sweat gland
151
Glycocalyx and cancer
A cancerous cell's glycocalyx might change almost continuously which lets it avoid the immune system
152
Tight junctions
Impermeable
Form seals around cell
Prevent molecules from passing between cells
153
Desmosomes
1. Anchoring junctions
2.bind adjacent cells like Velcro
3.helps keep cells from tearing apart
154
Gap junctions
1. Communicating junctions
2.lets ions and small molecules pass from cell to cell
3.important for heart and embryonic cells
155
Give an example where tight junctions are used
The epithelial cells in the digestive tract are joined by tight junctions. Prevent digestive enzymes and microorganisms from going into bloodstream. Some ions can sometimes pass through
156
"binding bodies"
Desmosomes
157
Plaque
Buttonlike thickening on inner surface of plasma membrane
158
Most important molecules cells use to interact with their environment
Cell adhesion molecules
Plasma membrane receptors
159
CAMS
1.Cell adhesion molecules
2. Almost on every cell in body
160
Function of CAMs
Embryonic development and wound repair
(Important where cell mobility is important)
161
Sticky glycoproteins
Cadherins integrins
Types of CAMs
162
Explain how CAMs work
1.Molecular Velcro that cells use to anchor themselves to other molecules in extra cellular space
2. Act as arms that help cells move against one another
3. Rally wbcs to infected or injured area
4. Transmit info about changes in extracellular matrix to cell. Bring a variety of responses like cell migration, proliferation, specialization
163
Membrane receptors
Large and diverse group of integral proteins that serve as binding sites . Some do contact signaling, others chemical signaling, glycoproteins
164
Contact signaling
Cells recognize each other. Important for immunity and development. Can be used by bacteria and others to identify target tissues
165
Chemical signaling
Usually comes from outside of the cell
Happens when a ligand binds to a receptor and starts a response
166
Ligands
Signaling chemicals that bind to membrane receptors
167
Types of ligands
neurotransmitters, paracrines, hormones
168
Paracrines
Chemicals that act locally and are rapidly destroyed
169
How do different cells respond to the same ligand?
Differently. Acetylcholine stimulates skeletal muscle to contract but inhibits heart muscle.
170
Why do target cells respond differently to the same ligand?
The reaction depends on the cell's internal machinery.
171
Explain how ligands work?
When a ligand binds to a receptor, the structure of the cell changes and proteins are altered in some way. For example the membrane proteins can become enzymes or they can open and close channels
172
G protein coupled receptors
Exert effect through a G protein
173
G protein
Relays signals between first (hormones or neurotransmitters)and second messengers (cAMP)
Helps activate or inactive a membrane-bound enzyme or ion channel
174
The activation of G proteins leads to
Second messengers. Intracellular chemical signals that mediate cellular response
175
cAMP and ionic calcium both activate
Protein kinase enzymes. Transfer phosphate groups from ATP to other proteins, activating a series of enzymes that cause the desired cellular activity
176
Explain how G proteins work
1. Ligand binds to receptor. Receptor changes shape and activates
2. Activated receptor binds to G protein and activates it. Causes the release of GDP and bind GTP
3. Activated G protein activates or inactives an effector protein by causing a shape change
4. Activated effector enzymes catalyze reactions that produce second messengers in the cell
5. Second messengers activate other enzymes or ion channels
7. Kinase enzymes activate other enzymes. Transfer P from ATP to specific proteins. Activate a series of enzymes that trigger metabolic and structural changes in the cell
177
Cytoplasm
Cellular material between plasma membrane and nucleus. Site of most cellular activities.
178
Part of cytoplasm
Cytosol
Organelles
Inclusions
179
Cytosol
Viscous,
Semitransparent fluid in which the other cytoplasmic elements are suspended.
Properties of both a colloid and a true solution
180
Which things are dissolved in the cytosol
Water, proteins, salts, sugars, others
181
Inclusions
Chemical substances that may or may not be present. Include stored nutrients, glycogen granules, lipid droplets in fat cells , pigment granules in skin and hair
182
Organelles
Metabolic machinery of cells
183
Which organelles lack a membrane
Ribosomes and centrioles
184
Why do membranous organelles need a membrane
To maintain a different internal environment than the surrounding cytosol
185
Threadlike or lozenge shaped organelles
Mitochondria
186
Active cells have more clusters of
Mitochondria
187
Mitochondria
ATP generation for cellular activities
188
Describe the structure of a mitochondrion?
Two membranes. Inner membrane folds and makes cristae. Folds make contact with matrix. Gel-like substance within the mitochondrion.
Enzymes within matrix break down intermediate products of food fuels (Glucose and others) to water and CO2
189
Important components of of mitochondria that let them reproduce themselves?
DNA, RNA, ribosomes.
190
What directs the synthesis of proteins needed for mitochondrial function?
Mitochondrial genes 37 make 1%
Cell's nucleus makes 99%
191
Fission
Mitochondria synthesize more cristae or pinch in half to increase their number and then grow their size
192
Ribosomes
Sites of protein synthesis. Has two subunits. Made of proteins and RNAs
193
Free ribosomes
Float freely in cytosol.
Make soluble proteins that work in cytosol, as well as those imported into mitochondria and other organelles
194
Membrane bound ribosomes
Attached to membranes. Form rough ER. Make proteins that are going to be incorporated into membrane or lysosomes or exported out of cell
195
Crenation
Water goes out of cell because it's in a hypertonic solution
196
Endoplasmic reticulum
System of interconnected tubes and parallel sacs called cisterns. Cisterns are filled with fluid
197
Continuous with outer membrane and accounts for half of the cell's membranes
ER
198
Rough endoplasmic reticulum
Studded with ribosomes
Makes proteins that go to golgi apparatus
199
Functions of rough ER
1. Makes secretory proteins. Abundant in antibody producing cells, liver cells. Make blood proteins
2. Membrane factory. Integral proteins and phospholipids are manufactured. Makes glycoproteins
200
Enzymes that catalyse lipid synthesis have their active sites on
External (cytosolic) face of ER membrane where needed substrates are available.
201
RAS
Most frequently mutated genes in human cancer.
family of genes that regulate cell growth and division. mutations can cause cancer
202
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