Final Exam Flashcards
1
Q
Who invented the microscope
A
Hans Lippershey / Hans and Zachairas Janssen
2
Q
Who is credited for the term “cell”
A
Robert Hooke
3
Q
Who is considered the father of biology
A
Antonie Van Leeuwenhoek
4
Q
Rank the following in order of size, smallest to largest
1. Organelles
2. Molecules
3. Cells
4. Atoms
A
4, 2, 1, 3
5
Q
Who discovered the nucleus
A
Robert Brown
6
Q
Who discovered that all plant tissues are composed of cells
A
Matthias Schleiden
7
Q
Who discovered that all animal tissues are composed of cells, respectively to Schleiden’s work
A
Theodor Schwann
8
Q
Who is most responsible for cell theory
A
Theodor Schwann
9
Q
What are the three components of cell theory
A
- all organisms consist of one or more cells
- the cell is the basic unit of structure for all living things
- cells only come from pre-existing cells
10
Q
What is the difference between a fact and the scientific method
A
facts are concrete, non negotiable, and do not evolve
the scientific method uses what is believed to be true, but can evolve over time with further observations
11
Q
What is the scientific method
A
- make observations
- create a hypothesis
- make predictions based on the hypothesis
- make further observations to test the hypothesis using controlled experiments
- interpret results
12
Q
What is a theory
A
A critically tested hypothesis under many conditions that becomes widely accepted by science
- the “solid ground” of science
13
Q
What is more solid than theory
A
Laws (ie. gas laws, gravity, etc.)
14
Q
What are the three strands of cell biology
A
biochemistry, genetics, and cytology
15
Q
All of the discoveries previously mentioned by scientists are considered in which branch of cell biology
A
cytology
16
Q
What is histology
A
the study of cells under microscope
17
Q
What is SEM vs TEM in electron microscopy
A
S=surface (images of the surface of cells)
T=through (scans through the middle of cells)
18
Q
What are the basic properties of all cells
A
atoms, molecules, macromolecules, organelles
19
Q
Where are the components of the cell enclosed
A
in the plasma membrane
20
Q
What is the central ‘genetic program’ used
A
The central dogma
21
Q
What is it called when cells acquire/use energy
A
bioenergetics
22
Q
What is it called when cells carry out chemical reactions
A
cellular metabolism
23
Q
What are the mechanical activities within cells
A
- transport of materials in/out
- assembly/disassembly of structures
- motility/movement
24
Q
What are examples of signal responses in cells
A
move away/toward stimuli, respond to hormones, growth signals, etc.
25
What is the order of the central dogma
DNA synthesis (replication), RNA synthesis (transcription), and protein synthesis (translation)
26
What are the two classes of cells
Prokaryotes - no nucleus
Eukaryotes - nucleus
27
What are the two domains of prokaryotes
bacteria and archaebacteria
28
What is the only bacteria without a cell wall
mycoplasma
29
Are most bacteria capable of carbon fixation
Yes, most can conduct photosynthesis
30
What is the most diverse cell group
prokaryotes - their most common shape being rod-shaped ("generic" bacterial cell)
31
Instead of a nucleus, what do prokaryotic cells have
1 long strand of DNA clustered together in the middle of the cell
32
What do prokaryotes and plants have in addition to the plasma membrane
a cell wall
33
Which type of cell has one large vacuole
plant cells
34
What are the four groups of eukaryotes
protists, fungi, plants, and animals
35
How are protists and fungi different from plants and animals
protists and fungi are mainly unicellular, plants and animals are multicellular
36
Which type of eukaryote are heterotrophs
plants
37
What is the difference between heterotrophs and autotrophs
hetero - self feeding
auto - have to digest plants to gain nutrients and organic compounds
38
What is the difference between the terms cytoplasm and cytosol
cytoplasm = everything within the plasma membrane, including organells
cytosol = just the fluid component
39
What is the endomembrane system
internal membranes that are either in direct contact or connected via transfer of vesicles
40
What are the components of the endomembrane system
nuclear envelope/membrane, ER, Golgi, lysosomes, vacuoles
41
Which organelles have their own genomes
mitochondria and chloroplasts
42
What does the cytoskeleton do
regulate cell shape and movement of materials within the cell
43
Where are the different locations of transcription and translation in the cell
transcription - in the nucleus
translation - at the ribosomes in the nucleus
44
What is the secretory pathway
proteins from the ER are transported out to the Golgi, and transported out from the Golgi as vesicles to be secreted from the cell
45
What is the endocytic pathway
molecules brought into the cell via phagocytosis that joins together with vesicles to create lysosomes
46
Based on the previous question, in what pathway are lysosomes produced
endocytic pathway
47
What is endosymbiont theory
eukaryotes are believed to have evolved gradually, and early organelles originated from prokaryotes and were engulfed by the cell (mitochondria and chloroplasts)
48
Ancient eukaryotic cells were anaerobic, why is that
Without the presence of the mitochondria, the cell could not use oxygen, therefore survived anaerobically
49
Ancient eukaryotes were autotrophs, why is that
Without the presence of chloroplasts, the cells could not fix their own carbon atmospheres, and could not complete photosynthesis
50
What evidence supports this endosymbiont theory
- mitochondria/chloroplasts are similar in size to bacteria
- have double membranes
- have their own ribosomes
- have their own genomes
- are genetically similar to the proposed "parent" bacteria
51
Is the organization of eukaryotic cells random
NO - this is ensured by the role of the cytoskeleton
52
Compare and contrast prokaryotes vs eukaryotes
prokaryotes: no nucleus, one naked strand of DNA, no membrane-bound organelles, cell wall, very small
eukaryotes: nucleus, membrane-bound organelles, multiple linear strands of DNA packed with histones, cytoskeleton, much larger
53
What is the model organism for transcription/translation
E. coli
54
What is the model organism for the cell cycle
yeast
55
What is the model organism for mammals
mice
56
What was the first genome to be sequenced
C. elegans (the worm)
57
What is the difference between ribose and deoxyribose sugars
ribose has a hydroxyl group on carbon 2, deoxyribose (think de-oxy), have only a hydrogen on carbon 2
58
What carbon connects to the base
carbon 1
59
What carbon connects to the phosphate group
carbon 3
60
DNA is found in helix and pleated sheet shapes, what are the shapes of RNA strands
RNA strands not confined to the continual helix shape, they are found in many winding shapes (still maintain base pairing, just in a less concrete fashion)
61
How does the shape of RNA matter
relates to the proteins and enzymes catalytic activities
62
Which DNA strand is the resulting mRNA strand identical to (minus T and U swaps)
the coding, non-template strand
63
Which direction is mRNA read vs built
read 3'-5', but only built 5'-3'
64
What type of bond is found between base pairs
hydrogen bond
65
What kind of bond is found in the sugar backbone
phosphodiester bonds
66
[The following is prokaryotic transcription]
this is important because it differs from eukaryotic transcription
67
At the active site of the transcription, what type of activity is required
catalytic activity
68
Can all types of cells produce various strands of mRNA simultaneously on the same template?
Yes - this is possible for prokaryotes and eukaryotes
69
What is holoenzyme comprised of
sigma factor and core enzyme
70
Where is the active site on holoenzyme
at the intersection of the channels running through it
71
What is core enzyme
core RNA polymerase
72
What happens when RNA poly binds to sigma factor
holoenzyme is formed and the DNA strand can be transcribed into mRNA
73
How does transcription start
start of a gene is recognized and bound by RNA poly; this is called the promoter sequence (immediately upstream of the gene)
74
Which strand is the promoter sequence located on
the coding, non-template strand
75
What are the components of the promoter sequence
-35 box and -10 box are base sequences located upstream on the DNA strand that make up the promoter sequence
76
Where on the strand does transcription begin
the +1 site
77
How long are promoter regions
40-50 bps long
78
Can a strand have more than one complementary sigma protein
Yes - for example, many bacteria have multiple sigma proteins for slightly variant sequences on the strand
79
What is the role of sigma factor once it has bound to the promoter
unwind helix and begin transcription - this process is called initiation
80
What happens in the elongation period of transcription
sigma factor releases and transcription continues
81
What happens in the termination period of transcription
RNA poly reaches a termination signal in the DNA template strand
82
What does the termination sequence do to the mRNA strand
codes for RNA that folds back on itself and forms a hairpin structure, disrupting the transcription progress
83
How is RNA released from the DNA strand and accompanying enzymes
RNA poly releases it
84
Once transcription is done and the mRNA strand has released, what happens to the accompanying enzymes
they also release, sigma factor rebinds to RNA poly to reform holoenzyme, and it moves to repeat the process with a new strand
85
How is the template strand determined
Promoters are asymmetrical and bind to polymerase in only one direction, it depends on the gene
86
Which strands promoter does the enzyme bind to
the promoter will end up being on the non-template strand - it depends on the gene for which strand that will be, but the promoter is always the non-template
87
[The following is eukaryotic transcription]
this is important because it differs from the previous prokaryotic transcription
88
What is different about DNA in eukaryotes
deal with DNA packaging (not just 1 long strand)
89
What are the types of RNA poly in eukaryotes
RNA poly I, II and III
90
What is different about eukaryotic promoters
they are more diverse and complex: many include a sequence called a TATA box (recognized by RNA poly II), while RNA poly I & III interact with completely different sets of promoters
91
What is required by eukaryotic RNA polys
accessory proteins - eg. general transcription factors that assemble at the promoter alongside RNA poly
92
What must happen to mRNA AFTER transcription in eukaryotes, that doesn't happen in prokaryotes
mRNA must undergo processing before leaving the nucleus
93
What are the three processing things that need to occur
addition of 5' cap
addition of poly-A tail
removal of introns
94
How are eukaryotic genes "spread out" in comparison to prokaryotic genes
include introns and exons, making them much longer than just one solid sequence of coding DNA - the introns in eukaryotic mRNA has to be removed for it to be efficient
95
How are introns removed
via "splicing" at the expense of spliceosomes
96
What is the final outcome of DNA protein packing
chromatin
97
What are the proteins involved in DNA packaging
histones
98
Why is DNA wrapped around histones, what is the purpose?
allows for compact packaging and more strict regulation of gene expression
99
How is transcription initiated in eukaryotic cells
TATA box is recognized by a TATA-binding protein (TBP)
100
What is TBP
TATA-binding protein, which is a subunit of TFIID (transcription factor II D)
101
How are transcription factors classified
Here, we are only seeing transcription factor II's, and they are classified by letter (in reality they are classified by both number and letter and perform a variety of tasks, were just only focused on one here)
102
What does the binding of TFIID allow for
distorts the helix (since it is part of initiation), and allows for more transcription factors (A, B, C, etc.) to be added on
103
When the transcription factors come together on the strand, what is formed
The transcription factor complex - this allows transcription to occur
104
What is the only constant TFII to be concerned about in this case
TFIID - recognizes the promoter region (TATA box)
- the rest of the TFII's vary by promoter
105
What does the TBP do to the helix itself
creates bends in the structure to partially unwind the helix and begin transcription
106
Once the complex is formed and transcription can be initiated, what happens
The enzymes break off, a phosphorylated tail is added, and TFIID stays on the strand - mRNA is transcribed
107
When is the processing factors completed on mRNA
during transcription
108
What enzymes carry out the processing
enzymes that ride on RNA poly II
109
What are the processes?
capping, splicing, and polyadenylation
110
What is polyadenylation in simpler terms
addition of poly-A tail to the sequence
111
Why is the 5' cap important
it is the recognition signal for translational machinery - the mRNA won't be converted into protein without it
112
Why is the poly-A tail important
it protects the protein from degradation once translation begins
113
Why is splicing important
removes non-coding portions of the mRNA sequence, making the sequence entirely coding for a specific gene
114
What is the primary transcript of mRNA
the mRNA BEFORE the introns are removed
115
When does splicing occur
AFTER capping, but still during transcription
116
How are introns cued to be removed
each intron has a short sequence at the beginning and end of its sequence that code for removal
117
What happens when introns are removed
it folds up into a structure similar to a hairpin, and branch point A attacks the splice site on the opposing end of the intron, cutting the splice site and creating a loop. the hydroxyl group on the end of the exon that has just been cut is now exposed, coming together with the splice site on the other side of the intron, removing the intron entirely and fusing the two exons together.
118
What happens to the lariat-shaped introns that have been removed
they degrade
119
What are spliceosomes made of
5 snRNPS (small nuclear ribonucleic particles) + RNA + 100 proteins
120
Where does the catalytic activity in snRNPs come from
the RNA
121
Are spliceosomes ribozymes?
Yes - they are made up of both ribosomal and protein components, making them ribozymes
122
What happens if introns are not removed
splice mutations occur and genetic malfunctions happen
123
What is the advantage of RNA splicing
can create different proteins from the same gene/strand with the removal of different pieces
124
What are the disadvantages of RNA splicing
more steps = more work
more steps = more opportunity for error (this creates greater opportunity for mutations or mistakes to occur)
125
Only _______ mRNA is exported from the nucleus
mature
126
What happens directly before mRNA can be exported
cap and poly-A tail are marked by proteins, a group of proteins called exon junction complex (EJC) binds to the mRNAs, and the mRNAs are finally able to be exported from nuclear pores into the cytosol
127
What is the genetic code
considers all 64 possible codons and matches them with their according amino acids (only 20 amino acids)
128
What is the most variable base in a codon
the third base
129
What is the exception of stop codons in the mitochondria
mitochondria in animal cells use the UGA stop codon to encode tryptophan, therefore it is not used as a stop codon in animal cells
130
Is the exception of mitochondria also applicable to plants
NO
131
What are examples of frame shift mutations
insertions & deletions
132
Who discovered tRNA molecules
Francis Crick (from the double helix invention of Waston and Crick)
133
The ____ end of the tRNA is the binding site for amino acids, while the loop opposite is the location of the ___________
3' end, anticodon
134
What is the wobble hypothesis
the third base in the sequence may not match the anticodon, but are still connectable based on variability
135
What is the purpose of the active site on tRNA synthetase
binds the ATP to the amino acid - this makes the amino acid now "active"
136
Once active, what happens with the tRNA synthetase
complementary tRNA is bound to the enzyme
137
Once the tRNA is bound to the enzyme containing its amino acid, what occurs
the amino acid and the tRNA bind together and are released from the enzyme as a now effective aminoacyl tRNA molecule
138
What are the components of a ribosome and where are they found in the cell
a large subunit and small subunit make up the ribosome, and these subunits are found dissociated from one another in the cytosol prior to activation
139
What is the function of the large subunit
catalyzes formation of peptide bonds
140
What is the function of the small subunit
matches tRNAs to the codons
141
Where does mRNA lie when the subunits are connected to form a ribosome
on the connective plane between the two subunits
142
When does translation begin
When the anticodon of a charged tRNA binds to a codon in mRNA
143
When does translation end
when that amino acid forms a peptide bond with growing chain
144
What are the three sites on the ribosome
A site - acceptor site for the aminoacyl tRNA
P site - peptide bond forms between adjacent amino acids
E site - the exit site of empty tRNA molecules
145
What initiates translation in eukaryotic cells
the AUG codon on the strand reached the MET amino acid with the help of a translational initiation factor and the small ribosomal subunit
146
What terminates translation in eukaryotic cells
presence of a stop codon, which is read and does not have a complementary tRNA molecule, instead it binds to a release factor molecule, which releases the amino acid chain (and the subunits then detach from the mRNA transcript and go back to their original state)
147
Is the ribosome and enzyme or a ribozyme
it is a ribozyme; it is an RNA molecule with a well-defined tertiary structure that enables catalytic activity (actions of both an enzyme and a ribosome)
148
In relation to the ribozyme classification, what is the large subunit completely made up of
RNA
149
Where are proteins found in ribosomes
mostly just on the surface, helping to maintain shape of the RNA core
150
What are polyribosomes
Multiple ribosome units come together on a strand to create multiples of the amino acid chain
151
Are polysomes big or small
they are significant in size due to the binding of various ribosomes at the same time
152
How is the process of transcription and translation different in prokaryotic cells
Everything happens simultaneously, since there is no nucleus, no processing occurs, and the strands do not have to undergo a transition of any sort between transcription and translation
153
Which is faster, prokaryotic or eukaryotic transcription and translation
prokaryotic - much less complicated and everything is simultaneous
154
When does protein folding begin
during translation
155
Although it requires no energy, what molecules often assist protein folding
molecular chaperones
156
What are post-translational modifications
chemical modifications of protein structure that generally involves addition of functional groups or small molecules
157
What are some types of post-translational modification (PTMs)
many types, including;
- glycosylation *
- addition of lipids
- phosphorylation *
- ubiquitination
158
What is the purpose of PTMs
effect shape, charge, and activity of the protein
159
What is the function of the plasma membrane
compartmentalization, selective permeability, transport, energy transduction, and respond to external signals
160
What are the 4 types of membrane phospholipid
PS, PE, PC, PI
161
Where are the 4 membrane lipids found
in the plasma membrane
162
Flashback: what are lipids made up of
polar head group, phosphate, glycerol, fatty acid chains
163
All membrane lipids are _______________
amphipathic
164
What does amphipathic mean
has hydrophilic and hydrophobic parts
165
In what way do lipid bilayers form
spontaneously
166
How do lipid bilayers physically form themselves
hydrophobic molecules exclude water and cluster together, drawing the hydrophilic components inwards and exposing the hydrophobic heads to the exterior
167
How are the conflicting forces of amphipathic molecules resolved
by the formation of a bilayer
168
What are the characteristics of lipid bilayers
closed, self-sealing (important for budding and cell fusion)
169
What is the "fluid mosaic model"
the organization of the lipid bilayer - with hydrophobic heads outward and hydrophilic tails inward, creating a fluid inner portion
170
How do phospholipids move within the bilayer
rotation of individual phospholipids in place and lateral diffusion WITHIN a leaflet
171
What movement does not occur in the lipid bilayer
movement BETWEEN leaflets rarely occurs because that would involve the hydrophobic head travelling through the hydrophilic tails
172
What impacts membrane fluidity
temperature and lipid composition
- tightly packed tails = less fluid, loosely packed tails = more fluid
173
In what circumstances will lipid fluidity change
if temp changes at a constant composition, or if composition changes at constant temp
174
What is Tm
transition temp; the temp at which a membrane transitions between the fluid phase and the gel phase
175
What happens above Tm? and what happens below Tm?
above = increased fluidity, the membrane "melts" - this is good
below = decreased fluidity, the membrane "gels" - this is bad
176
What is Tm affected by
altered length of fatty acid chains: longer tails mean more tightly packed and less fluid, takes more to melt
altered amount of saturated fatty acids: more double bonds means less packing and more fluid, takes less to melt
altered amount of sterol (cholesterol): higher cholesterol at cool temps, membrane more fluid, and higher cholesterol at low temps, membrane less fluid
177
What is the typical lipid composition in the tails of membrane phospholipids
Usually, one tail is saturated and done contains one or more double bonds
178
How to organisms adapt to temps and maintain membrane fluidity
dealing with low temps: shorter fatty acid chains & increase double bonds
179
What are desaturate enzymes
triggered in organisms at low temps, enable the phospholipids to be desaturated
180
How are extremophiles different from other organisms in the sense of lipid composition
extremophile archaebacteria have branched isoprene chains in place of the fatty acid chains
- this results in L-glycerol instead of D-glycerol and ether linkages instead of ester
181
What are the classifications of lipid proteins
transmembrane, monolayer-associated, lipid-linked, and protein linked
182
Hydrophilic channels are formed from several __ __________
a-helices
183
Proteins folded into ________ ________ can create pores
pleated sheets
184
What is an example of how cells can constrict movement of membrane proteins
tight junctions - prevent apical and basolateral proteins from moving to opposing sides of the cell
185
Where are sugars found on eukaryotic cells
on the exterior (in the extracellular space)
186
Why is the bilayer asymmetrical
due to the sugars on the extracellular side but not on the cytosolic side
187
What is the most extensive part of the cell
the ER
188
Why does the ER synthesize proteins
secretion, insertion into membranes, and lysosome formation
189
How does the ER assemble the membrane
adds free fatty acids in the cytosol to the cytosolic side of the membrane, and scrambles scramble the phospholipids around to ensure equal amounts on both sides
190
How does the Golgi assemble the membrane
via flipases, the PS and PE heads are moved to the cytosolic side (so non-cytosolic side consists only of PI and PC, while the cytosolic side consists of PS and PE along with leftover PI and PC
- this creates membrane asymmetry from this point forward
191
What are the components of the cytosolic side of the bilayer
PS & PE (with leftover PC/PI)
192
What are the components on the non-cytosolic side
Only PC and PI, with sugar components
193
What remains equal amongst both sides of the bilayer
cholesterol
194
What are the model organisms for the plasma membrane
RBCs
195
When a solute is added to solution, what happens to achieve no NET flux
the solutes spread out evenly throughout the solution to create equal concentration
196
What is another term for solutes in relation to osmosis
osmotically active particles
197
When concentrations are equal on both sides of a membrane, the cell is ________
isotonic
198
When the concentration is greater on the exterior of the membrane, the cell is ________
hypertonic (loses water to exterior)
199
When the concentration is greater on the inside of the membrane, the cell is ________
hypotonic (gains water)
200
What is the normal state for an animal cell vs a plant cell
animal = isotonic
plant = hypotonic (turgid)
201
What are the three terms for plant cell state based on osmosis
turgid (ideal), flaccid, and plasmolyzed
202
What is turgor pressure
pressure of the cell contents against the cell wall in plant/bacterial cells
203
What are osmoconformers
ex. marine animals; adjust internal salt concentrations to match seawater
204
What are osmoregulators
single-celled eukaryotes have contractile vacuoles that pump out water (they don't have a cell wall)
205
List in order, the permeability of the following from most permeable to least permeable...
1. ions
2. small nonpolar molecules
3. small uncharged polar molecules
4. large uncharged polar molecules
2, 3, 4, 1
206
How are carriers and channels different
Carriers: specific to substrates, remain in a "closed" position until bound to the proper molecule
Channels: open, free flow
207
How are carriers and channels similar
Both passageways for particular classes of molecule, and most are multi-pass, move things down their concentration gradient
208
What makes channels selective
focuses on charge and size of the molecules
209
What is chemical vs concentration gradient
chemical: how much of a specific solute resides on either side of the membrane
electrical: whether it is being attracted by its opposite charge, or repelled by like charges
210
Who gained a Nobel prize for the selectivity of the potassium channels
Roderick MacKinnon
211
What are the 4 types of channels talked about
voltage-gated, ligand-gated (inner vs outer), and mechanically-gated
212
Carriers mediate which type of transport
passive, facilitates diffusion
213
What is an example of a solute moved by carrier proteins
GLUT1
214
Transporting against a gradient is which type of transport
active transport - uses energy to move solutes "up hill"
215
What was the first pump to be discovered
sodium potassium pump
216
How does the sodium potassium pump work
moves Na+ in and K+ out in a 3:2 ratio respectively
217
Why is sodium potassium pump electrogenic
creates a charge due to the imbalanced transfer ratio
218
What is the enzyme that regulates the sodium-potassium pump, and what is its significance
Na/K ATPase: both a membrane protein and an enzyme, its present in ALL animal cells (contributes to basal metabolic rate), maintains Na+ gradient and uses it to transport other molecules
219
How does activation of pumps occur
phosphorylation of the membrane protein to activate the function
220
How are pumps and carriers different
Carriers are passive, pumps are active
Carriers move down a gradient, pumps move against a gradient
221
What is coupled transport
when more than one molecule is being transported across the membrane at once (opposite of uniport)
222
What is symport vs anti port
symport: moving 2 molecules in the same direction
antiport: moving 1 molecule one direction and 1 the other
223
Coupled-mediated transport is also known as ________ _____________ ____________
indirect/secondary active transport (eg. glucose into the bloodstream via the action of the Na/K pump)
224
What type of pump is common in plant cells
proton pumps
225
What determines the transporters located on a specific membrane
the genes present in the protein
226
What would happen if a mutation occurred in a transmembrane protein
channelopathies (ion channel diseases) where things either cannot be transported as they should or things are being transported that should not be passed through
227
How is the evolution of the nucleus and ER similar to that of the mitochondria
thought to have been absorbed by a bigger cell, and implemented in the make up of a cell at some point in time
228
What are the three ways to transport proteins into organelles
nuclear transport, transport across membranes, and transport by vesicles
229
What would happen as a result of the deletion of a signal sequence
the protein would reside in the cytosol, because it no longer contains its "address"
230
Describe the nuclear pore complex
highly selective gates, nuclear pores contain a nuclear basket that only allows for the passing of specific solutes
231
How are proteins imported into the nucleus
contain a nuclear localization signal, that binds to a nuclear import receptor, and passes through the pore accordingly
232
All except proteins are small enough to be _______ transported into the nucleus through the pores
uniport
233
do proteins fold as they pass through nuclear pores while bound to the receptor signal?
NO
234
What are examples of things moving OUT of the nucleus
mRNA and rRNA
235
What are examples of things moving INTO the nucleus
histones (DNA packing), proteins required for transcription, dNTPs and rNTPS
236
What is important to remember about the mitochondria membrane
it is double layered - there are two membranes
237
What part of the protein initiates the transfer into the mitochondria
the signal sequence
238
What does the signal sequence on the protein bind to on the ER outer membrane
an import receptor protein
239
Once attached to the import receptor protein, what happens next
a protein translator on the inner membrane matches the import receptor on the outer membrane and binds to form a transmembrane path for the protein
240
Once inside the mitochondria, what is the last step of the protein transport
the signal sequence is cleaved off, to reveal the functional protein
241
What terminus is the signal sequence located at on the protein
the N terminus
242
What is important to consider about protein shape in relation to transport
the protein must unfold to be transported across the mitochondrial membrane
243
Transport within an organelle happens how?
a new signal sequence is revealed when the original one is cleaved off, allowing for the same process to be repeated within the organelles
244
What is the most extensive membrane system
the ER
245
How is the ER vital for transport
serves as an entry point for itself and the rest of the endomembrane system,, including Golgi, lysosomes, endosomes, etc.
246
Once in the ER, can proteins go back into the cytosol?
NO
247
What are the two types of ribosome cycles
free in cytosol, and membrane-bound to ER
248
When does mRNA translate into the ER
When the strand presents a signal sequence targeting the ER and binds to protein translocators
249
Explain the process of ribosomal function on the ER membrane
The peptide strand displays a signal sequence that binds to a signal recognition particle (SRP). The SRP binds to an SRP receptor on the surface of the ER membrane, which connects with a translocation channel. Once all connected, the peptide chain can pass down into the ER lumen
250
What are the two types of proteins transferred into the ER
water-soluble proteins destined for the lumen, and transmembrane proteins only partially tranlocated across, destined for plasma membrane, ER membrane, or membrane of another organelle
251
What is a single pass protein
a protein that partially passes the membrane only once, so one side is in the organelle, and the other is out in the cytosol
252
What is a multi pass protein
a protein that partially passes the membrane various times, so parts of the protein are inside the organelle, and some parts are not (ie. GPCR)
253
Are vesicles permanent or temporary
temporary
254
Describe the pathway of a vesicle moving OUT of the cell
ER, Golgi, (other organelles), plasma membrane
255
Describe the pathway of a vesicle moving INTO the cell
plasma membrane, endosomes, lysosomes
256
What is the most common protein coat discussed
clathrin
257
How are coat proteins applied to a vesicle
cargo molecules match with cargo receptors within the extracellular space and bind to adaptin and a protein coat on the cytosolic side. the protein coats pull the receptors, which eventually bud off as vesicles, entirely surrounded by the protein coats
258
What cuts the vesicle away from the plasma membrane
dynamin
259
Once the coated vesicle has been cut from the membrane, what happens?
the protein coats release from the vesicle, and the naked vesicle can now be transported effectively
260
What does vesicle docking depend on
tethers and snares
261
What are Rab proteins
monomeric GTPases displayed on the vesicle surface
262
What are tethering proteins
proteins that extend from the outer surface of the membrane, and bind to the Rab protein on the vesicle
263
What are snares
v-snare = v for vesicle, snare located on the outer surface of the vesicle
t-snare = snare located on the membrane
- snares intertwine together and pull the vesicle towards the membrane to fuse
264
Upon fusion, where is the cargo protein
successfully implanted in the membrane
265
How are proteins covalently modified in the ER
- disulphide bonds are added in between proteins and within protein folding
- glycosylation (addition of sugar groups) to protect protein degradation, direct to proper organelle, and allow for cell-cell recognition
266
Explain N-linked glycosylation in the ER
as the protein enters the ER membrane via the transmembrane pathway, N-acetylglucosamine in a lipid-linked oligosaccharide breaks away from the phosphate group and attaches itself to the asparagine (Asn) amino acid
267
Only properly __________ proteins are allowed to leave the ER
folded
268
What assists in refolding misfolded proteins
chaperone proteins
269
How does the ER detect misfolded proteins
hydrophobic residues that should be tucked away are recognized by the ER
270
What is the UPR
unfolded protein response: various proteins on the outer surface of the ER membrane set off a series of events in the cytosol that activate chaperone genes
271
What happens if there are too many misfolded proteins that cannot be fixed
accumulate together and kill the cell
272
Cis and trans ends of the Golgi network
Cis end = close to ER
Trans end = close to plasma membrane
273
What is the name for the series of flattened sacs that make up the Golgi
cisternae
274
What are the functions if the Golgi
- modify proteins arriving from the ER: peptide chains shortened by proteases, amino acids modified, CHO groups added in ER modified or removed, glycosylation
- most complex polysaccharides synthesized in the Golgi
275
What is O-linked glycosylation
Different CHO groups added to different AAs (set, thr)
276
What is the difference between constitutive vs regulated secretion
constitutive: unregulated, involves plasma membrane proteins, happens at all times
regulated: regulated, involves signal transduction, happens upon signalling
277
What is the endocytic pathway
taking substances into the cell by surrounding them with a membrane
278
What are the 2 main types of endocytic pathway
pinocytosis = cell drinking
phagocytosis = cell eating
279
What is the difference between pinocytosis and phagocytosis
pino = 'drinking' because it involves much smaller vesicles formed called endosomes
phago = 'eating' because it involves much larger vesicles formed called phagosomes
280
What is the third type of endocytosis in animal cells
receptor-mediated endocytosis
281
How does receptor-mediated endocytosis work
particular molecules called ligands match receptors on the membrane called coated pits, and bind/fuse
282
What are the sites of cellular digestion
lysosomes
283
What are the three digestive processes in lysosomes
endocytosis, phagocytosis, autotrophy
284
What are the three components that come together to form a lysosome
phagosome, autophagosome, and late endoscope
285
What are the two types of short-range communication
paracrine and contact-dependant
286
What are the two types of long-range communication
endocrine and neuronal
287
What's another term for signalling molecule
ligand
288
Explain the steps of a signalling pathway
ligand synthesized and released by signalling cell
signal molecule travels to the target cell
signal binds to a receptor protein
change in protein activity results in a change in gene expression
change in cell shape, movement, metabolism, secretion, etc.
289
What is the basis of signal receptors
ligand binds and alters a function
290
What are the two types of signal receptors
cell-surface and intracellular
291
What is an example of small hydrophobic signal molecules that can cross the membrane into the cell
steroids
