summery Flashcards
1
Q
Basic structures of viruses:
A
1) a nucleic acid genome
2) a protein capsid that covers the genome.
2
Q
Cell Theory:
A
- All living organisms are composed of one or more cells.
- The cell is the most basic unit of life.
- All cells arise only from pre-existing cells.
3
Q
Basic properties of cells (9) (CGRECMSSE)
A
- Highly COMPLEX and ORGANIZED.
- Activity controlled by a GENETIC program.
- Can REPRODUCE—make copies of themselves.
- Assimilate and utilize ENERGY.
- Carry out many CHEMICAL reactions (enzymes).
- Engage in MECHANICAL activities.
- Respond to STIMULI.
- Capable of SELF-REGULATION.
- They EVOLVE.
4
Q
What Does it Take to Make a CELL ? (3)
A
- information
- chemistry
- compartments
5
Q
Two MAIN cell types:
A
Prokaryotic and
Eukaryotic Cells
6
Q
The _____ is a dynamic INFORMATION system
A
GENOME
7
Q
Cell function is dependent on ______ reactions occurring in _______
A
CHEMICAL, COMPARTMENTS
8
Q
what are viruses?
A
Viruses are macromolecular packages that can function and reproduce only within living cells.
9
Q
Outside of cells, viruses exist as
A
inanimate
particles called VIRIONS.
10
Q
Structure of viruses (3)
A
- Protein coat (capsid) that
surrounds nucleic acid - Enclosed in a protein-
containing membrane
(enveloped) or not (naked
or unenveloped) - Nucleic acid either RNA or DNA; encodes viral
proteins
– Thus, either RNA or
DNA viruses
11
Q
Two main types of viral life cycle:
A
NON-LYTIC (also known as LYSOGENIC)
LYTIC
12
Q
NON-LYTIC (also known as LYSOGENIC)
A
– Viral nucleic acid is replicated in the host; viral proteins produced
– Virus reproduces without destroying the host cell
13
Q
LYTIC
A
– Production of virus particles ruptures (and kills) host cell (e.g.,
bacteriophages; ebola virus)
14
Q
how do RNA Vaccines work?
A
tricking the body’s cells into producing a fragment of a virus, an antigen, from an RNA template
15
Q
Main factor that determines what cell type a virus can infect
A
surface expression of a specific surface protein
16
Q
Functions of Biological Membranes (6)
A
1) Define cell boundary
2) Define enclose compartments
3) Control movement of material into and out
of cell / organelles
4) Allow response to stimuli
5) Enable interactions between cells
6) Provide scaffold for biochemical activities
17
Q
Phospholipid Structure
A
- Phospholipids consist of a glycerol backbone bound by:
– Two non-polar fatty acyl
molecules (“fatty acid chains”)
– A polar head group linked by a phosphate residue
18
Q
Lipid molecules, like phospholipids, spontaneously aggregate to bury their _____ in the interior and expose their _____ to water
A
hydrophobic tails, hydrophilic heads
19
Q
Where does phospholipids of membranes come from?
A
- Synthesis occurs in a multistep process at the interface of the cytosol and outer endoplasmic reticulum membrane
20
Q
Membrane Proteins (3)
A
INTEGRAL, PERIPHERAL, LIPID-ANCHORED
21
Q
INTEGRAL membrane proteins…
A
span the lipid bilayer
22
Q
PERIPHERAL membrane
proteins associate with…
A
the surfaces of the lipid bilayer
23
Q
LIPID-ANCHORED proteins attach to…
A
a lipid in the bilayer
24
Q
Integral Protein Functions: (3)
A
1) Transport of nutrients and ions.
2) Cell-cell communication (gap junction)
3) Attachment
25
Biological Membranes are: (3)
* Stable
* Flexible
* Capable of self assembly
26
Membranes also have unique features: (2)
* Different membranes contain different types of lipids and proteins, giving them different functions.
* Differences between cells as well as within organelles
within a cell.
27
The inner membrane of mitochondria contains a ______ concentration of protein necessary for electron transport chain and ATP synthesis.
very high
28
Myelin sheath simply consists of layers of
_____ wrapped around the a neuron’s axon.
plasma membrane
29
Myelin sheaths have ____ of protein.
low amounts
30
Biological membranes are symmetrical or asymmetrical?
asymmetrical
31
Two leaflets have distinct lipid composition in many plasma membranes, the
outer leaflet contains...
glycolipids and glycoproteins
32
Temperature is an important variable affecting the fluidity
of biological membranes:
* Warming _____ fluidity
* Cooling ___ fluidity
increases, decreases
33
Membrane fluidity is determined by the nature of ____ in membrane
lipids
34
- Unsaturated lipids ___ fluidity
- Saturated lipids ___ fluidity
increase, decrease
35
In response to changes in temperature, lipid composition of membranes can be changed by:
1) desaturation of lipids
2) exchange of lipid chains
36
BALANCE between ordered (rigid) structure and disordered structure
allows: (3)
* Mechanical support and
flexibility.
* Membrane assembly and
modification.
* Dynamic interactions between
membrane components
37
Cholesterol acts as a _____ regulator of membrane fluidity
bidirectional
38
* At high temperatures, cholesterol _____ the membrane and _____ its melting point
* At low temperatures, it ____ and prevents them from ______
stabilizes, raises, intercalates between the phospholipids, clustering together and stiffening.
39
If cholesterol is added to a crystalline gel membrane, fluidity will...
increase
40
If cholesterol is added to a liquid crystal membrane, fluidity will...
decrease
41
Membranes are composed of
LIPID BILAYERS
42
Amphipathic
having both hydrophilic and hydrophobic parts
43
______ are main structural components of biological membranes
PHOSPHOLIPIDS
44
Cells with different functions have...
membranes with different protein compositions
45
The transmembrane domain (TMD): (3)
* Is an α helical peptide sequence that is largely hydrophobic (uncharged) and spans the membrane; consists of amino acids with hydrophobic side chains
* Is permanently attaches the protein to the PM.
* Can facilitate protein-protein interactions
α helices
46
_____ molecules cross membranes relatively easily
Small, uncharged
47
Four basic mechanisms for moving molecules across membranes
1) Simple diffusion
2) Diffusion through a channel
3) Facilitated diffusion
4) Active transport
48
Passive movement
- Moves from a HIGH to a LOW concentration
- DOES NOT require energy
49
____ are specific water channels
AQUAPORINS
50
Channels are formed by
____ that line an aqueous
pore
integral membrane proteins
51
Channels are particularly effective for...
small,
charged molecules (ions)
52
Ion channels are often...
gated
53
Two types of Gated Ion Channels
1) Voltage-gated channels
2) Ligand-gated channels
54
Voltage-gated channels respond to...
changes in charge across membrane
55
Ligand-gated channels respond to...
binding of specific molecule on its surface
56
Binding of a ligand produce ____ in the structure of the receptor/channel
conformational change
57
Compound binds specifically to integral
membrane protein called a...
facilitative transporter
58
Most animal cells import glucose from the
blood into cells via a...
facilitative transporter
59
steps of glucose transporter (4)
1) Transporter ready to accept glucose molecule
2) Glucose is accepted by transporter
3) Intracellular side of transporter opens
4) Glucose is released and cycle repeats
60
The concentration gradient of one molecule is used to transfer a second molecule in opposite directions
Antiporter
61
Active transport:
* Compound binds specifically to integral
membrane protein called an ACTIVE TRANSPORTER.
* Change in the conformation of the
transporter caused by the hydrolysis of an ATP molecule allows molecules to be released on other side of the membrane.
* Using this mechanism, compounds can move
against a concentration gradient
62
Tetrodotoxin (TTX) and curare are toxins that interfere with...
movement through ion channels
63
Proteoglycans
proteins with chains of polysaccharides
64
Functions of the ECM (4)
(CCCB)
* Cell adherence
* Communication between cells
* Cell shape
* Serves as barrier
65
Anchor membrane proteins (e.g., integrins) assists in: (2)
- Tissue formation and coordinated cell function
- Communication between cells
66
Membrane proteins play a major role in signal
transduction by converting an ____ signal into ____ signal
extracellular, intracellular
67
Signal transduction allows cells to rapidly
respond to events happening in their
environment: (5)
* Grow
* Divide
* Survive (or not)
* Move
* Differentiate (i.e., time to change
68
Three stages to signal transduction
1) Binding of ligand to receptor
2) Signal transduction via second messengers like cAMP, calcium, or G-protein
3) Cellular response: cellular growth, cell division, store glucose
molecules as glycogen
69
____ is an enzyme that will release glucose units
Phosphorylase-P
70
Aerobic respiration:
converts in presence of oxygen energy stored in food molecules (e.g., glucose) into chemical energy stored in ATP.
71
Photosynthesis:
building carbohydrates using energy from sunlight
and CO2
72
Outer Mitochondrial Membrane (OMM) contains:
(2)
* many enzymes with diverse metabolic functions
* porins, which are large channels permeable (passive diffusion) to many molecules when opened (e.g. ATP, sucrose)
73
Inner Mitochondrial Membrane (IMM):
* High protein: lipid ratio (3:1)
* Double-layered folds are called cristae
* Rich in a phospholipid called cardiolipin
74
The mitochondria also has two aqueous compartments:
* Intermembrane space separates OMM and IMM
* Matrix
75
Matrix:
a high protein content, gel-like consistency space containing mitochondrial ribosomes and mitochondrial genome
76
Cellular respiration involves a series of ____ reactions.
catabolic
77
Substrate-level phosphorylation:
Hydrolysis reaction releases enough energy to drive phosphorylation of ADP to ATP
78
Oxidative phosphorylation:
Chemical energy of organic molecules is transferred to electron carriers that is used to create an electrochemical gradient that can power ATP synthesis
79
which phosphorylation produces more ATP
Oxidative phosphorylation (88%)
80
Coenzymes acting as electron carriers can exist
either as:
1) Oxidized—can accept electrons
2) Reduced—can donate electrons when
returning to their oxidized state
81
Mitochondria Oxidative Phosphorylation steps (2)
1) Generate an electrochemical gradient
2) Proton movement down electrochemical gradient to power ATP synthesis
82
Photosynthesis can be divided into...
light-dependent reactions and light- independent reaction
83
Light-Dependent Reactions occur in
thylakoid membrane
84
Light-Independent Reactions occur in
stroma of chloroplasts
85
Apoptosis is Initiated by
intracellular stimuli like genetic damage, hypoxia, or virus infection
86
“Killer” proteins like ____ causes change in mitochondria membrane
potential and to the leak of ____
Bax, Cytochrome c
87
Key elements of vesicle trafficking to a compartment:(4)
1. Movement of vesicle.
2. Tethering vesicle to target compartment.
3. Docking of vesicle to target compartment.
4. Fusion of vesicle and target membrane
88
Docking of vesicle to target compartment uses proteins called...
SNAREs.
89
Photophosphorylation creates ____ necessary for
carbohydrate synthesis through ____
ATP and NADPH, Calvin cycle
90
_____ are ENZYMES (proteases) that activate proteins that
are involved in dismantling the cell
CASPASES
91
Functions of Smooth ER (SER) (4)
1. Lipid synthesis
2. Production of steroid and hormones
3. Detoxification
4. Sequestration (storage) of Ca2+
92
Functions of Rough ER (RER) (4)
1. Synthesis of membrane phospholipids.
2. Glycosylation of proteins
3. Protein folding — quality control
4. Protein synthesis, modification, and transport
93
where and how does Protein Synthesis occur?
In the cytoplasm, ribosomes synthesize polypeptides from mRNA
94
Translation is completed in 1 of 2 ways:
FREE or ER BOUND ribosomes.
95
Ribosomes are targeted to the ER membrane by a specific...
signal sequence
96
The signal sequence is: (3)
* Located in the amino-terminus (N-terminus)
* Contains several consecutive hydrophobic amino acids
* Directs synthesis to the ER compartmen
97
Protein moves through channel into ER for...
cotranslational
import
98
Cotranslational Protein Import steps (4)
1. After translation of SIGNAL SEQUENCE, a Signal Recognition Particle (SRP) binds to signal sequence and STOPS the translation
2. SRP binds SRP receptor to target the whole translation complex to ER
3. SRP is released and ribosome binds to translocon. Once this is done, protein synthesis resumes
4. Polypeptide enters the ER (through the translocon) as it is translated. In the end, the signal peptide is cleaved off and chaperone folds the protein
99
To the plasma membrane via biosynthetic/secretory pathway =
exocytosis
100
From the plasma membrane → organelle within cell via endocytic pathway =
endocytosis
101
A protein targeted to the ER lumen, after it is fully synthesized and properly folded, has 1 of 2 options:
Option 1. It is retained in the ER lumen, if that is where it functions.
Option 2. It is transported from the ER to the Golgi complex for further modification and delivered to distal parts of the biosynthetic/secretory pathway
102
Material moves from ER to Golgi and then to other compartments and the plasma membrane in a
_____ direction.
proximal to distal
103
_____ acts as a sorting station (i.e., sorts whether proteins should continue on to the next Golgi station or be shipped back to the ER)
cis Golgi network
104
_____ sorts protein into different types of vesicles—vesicles go to plasma membrane or other intracellular destinations (e.g. lysosomes)
trans Golgi network
105
In addition to sorting, the Golgi is also involved in synthesis of _____ and specific modification of _____
polysaccharides, proteins and lipids
106
The transfer of vesicles from ER to Golgi, and between the Golgi sub- compartments, is achieved by ____
coat
proteins
107
Coat proteins have 2 functions:
1. Helps form the vesicle.
2. Helps select ‘cargo’
108
COPI and COPII are _____ that assemble on the
______ of donor compartment membranes at sites where budding takes place
protein complexes, cytosolic surface
109
COPI-coated vesicles move in____ direction
retrograde
110
COPII-coated vesicles move in ____ direction.
anterograde
111
Two-layered coat consists of:
* Clathrin - coat protein
(outer layer)
* AP complex = Clathrin
Adaptor Protein complex
(inner layer)
112
AP/Clathrin-coated vesicles move from ____ to other compartments
trans Golgi network
113
Lysosomal membrane is
composed of ____ that act as a protective lining next to acidic lumen
glycosylated proteins
114
Lysosomes Function (2)
1. Autophagy
2. Degradation of internalized materials
115
Autophagy:
Normal disassembly of unnecessary or dysfunctional cellular components
116
Tonoplast:
Vacuolar membrane that contains active transport systems that allows ion and molecule transport
117
Function of Plant Vacuoles (3)
1. Intracellular digestion
2. Mechanical support
3. storage
118
Cytoskeleton
Dynamic network of interconnected filaments and tubes that extends throughout the cytosol (and some organelles) of eukaryotes
119
Functions of the cytoskeleton:
1) structural support
2) spatial organization within cell
3) intracellular transport
4) contractility and motility.
120
Axonemal microtubules
* Highly organized, stable
* Part of structures involved in cell movement
121
Cytoplasmic microtubules
* Loosely organized, very dynamic
* Located in cytosol
122
Microtubules Structure
13 protofilaments form longitudinal array creating an hollow cylinder
123
Heterodimers are aligned in the ___ direction creating ____
same, structural
polarity
124
The Microtubule-Organizing Center is only found in...
eukaryotic cells.
125
Microtubule-Associated Proteins (MAPs)
Several different proteins that bind MT
126
Microtubule-Associated Proteins function
* Modulate assembly, function
* Mediate interactions with other cellular structures
127
Two major classes of
MAPs
Non-Motor and motor Proteins
128
MT-Associated Non-Motor Protein function
Control MT organization in cytosol
129
two types of MT-Associated Motor Proteins
kinesin and dynein
130
MT-Associated Motor Proteins function (3)
* Use ATP to generate force.
* Can move material along MT track.
* Can generate sliding force between MTs.
131
Kinesin = ___ end-directed
plus
132
Dynein= ___ end-directed
minus
133
Microfiliments have several important functions: (5)
* Maintenance of cell shape
* Cell movement
* Vesicle transport
* Muscle contraction
* Cytokinesis
134
Actin is the...
central component of MFs
135
Actin exists in cells either as a ____ or as a ____
monomer, polymer
136
F-actin microfilaments can be arranged in a loose array network
(meshwork) or tight bundles/cables/fibers. The organization of these
structures is regulated by:
actin-binding proteins
137
Myosins:
a superfamily of motor proteins associated with microfilaments.
138
Most myosin molecules move toward the ___ end of microfilaments.
‘plus’
139
myosin are Divided into 2 broad groups:
1) Conventional myosins
2) Unconventional myosins
140
Conventional myosins
* Type II
* Primary motors for muscle contraction
141
Unconventional myosins
* Type I and types III-XVIII
* Organelle / vesicle movement
142
_____ generate force and contribute to motility in non- muscle cells
Unconventional myosins
143
Microtubule-based and microfilament-based motors can cooperate in...
intracellular transport
144
Intermediate Filaments (IF) function
Provide structural support and mechanical strength.
145
Intermediate filaments
composed of ___ in the cytoplasm are stained red
keratins
146
ntermediate filaments
composed of ___ in the nucleus are stained blue
lamins
147
Intermediate filaments are especially abundant in the...
axons of neurons
148
Nucleus Function (3)
1. Storage, replication, and repair of genetic material.
2. Expression of genetic material
3. Ribosome biosynthesis
149
Nucleus Structure
Nuclear envelope
* Nuclear membrane
* Nuclear pores
* Nuclear lamina
Nuclear content
* Chromatin
* Nucleoplasm
* Nucleolus
150
The Nuclear Envelope Structure
2 parallel phospholipid bilayers separated by 10-50nm space
151
Outer nuclear membrane (ONM)
binds ribosomes and is continuous with rough endoplasmic reticulum
152
Inner nuclear membrane (INM)
has integral proteins and connects to nuclear lamina
153
Importance of the Nuclear Envelope (3)
* Separates nuclear content from cytoplasm
* Separates transcription and translation processes
* Selective barrier that allows limited movement of molecules between nucleus and cytoplasm
154
The Nuclear Lamina
Provides structural support for nuclear envelop
155
Lamins (intermediate filaments) are found in...
animal cells only
156
Nuclear lamina is bound to ____ of the nuclear
envelop (NE) by _____
inner membrane, integral membrane proteins
157
Nuclear Pore
Gateways between cytoplasm and nucleus
158
The Nuclear Pore Complex (NPC) is:
Composed of nucleoporins (NUPs)—a large family of different proteins
159
Nuclear Import
Regulated movement of proteins into the nucleus
160
Nuclear Import requires an:
intrinsic amino acid targeting sequence - Nuclear Localization Signal (NLS)
161
NLS =
several positively charged amino acids within the protein sequence.
162
Nuclear Import steps
1. Protein with NLS (cargo) interacts with Importin protein in cytoplasm
2. Cargo/Importin complex interacts with FG-NUPs at the NPC and enters the nucleoplasm
3. Ran-GTP (G-protein) interacts with Importin; cargo dissociates and stays in nucleoplasm
4. Ran-GTP/Importin complex exits nucleus through NPC
5. GTP hydrolysed to GDP. Importin released in cytoplasm to find new cargo
163
Nucleolus
Largest structure inside the nucleus of eukaryotic cells.
164
Primary function of the nucleolus is
biosynthesis of ribosomes.
