Eukaryotic Cells Flashcards
(215 cards)
1
Q
Function of the nucleus?
A
contain and protect DNA, transcription, partial assembly of ribosomes
2
Q
Function of mitochondria?
A
produce ATP via the Krebs cycle and oxidative phophorylation
3
Q
Function of ribosomes?
A
synthesize proteins
4
Q
Function of rough ER?
A
location of synthesis/modification of secretory, membrane bound, and organelle proteins
5
Q
Function of smooth ER?
A
detoxification and glycogen breakdown in liver, steroid synthesis in gonads
6
Q
Function of golgi apparatus?
A
modification and sorting of protein, some synthesis
7
Q
Function of lysosomes?
A
contain acid hydrolases which digest various substances
responsible for degradation of biological macromolecules by hydrolysis
8
Q
Function of peroxisomes?
A
metabolize lipids and toxins using H2O
9
Q
The nucleus contains the genome surrounded by a ______ ______.
A
nuclear envelope (not accessible to the cytoplasm)
10
Q
In Eukaryotes, replication, transcription, and splicing occur in the ______. Translation occurs in the _______.
A
Nucleus
Cytoplasm
11
Q
Yeast have _____ chromosomes, humans have _____.
A
4
23
12
Q
Centromeres?
A
structure near the middle of eukaryotic chromosomes to which the fibers of the mitotic spindle attach during cell division
13
Q
Telomeres?
A
have large numbers of repeats of a specific DNA sequence that help maintain the ends of the linear chromosomes during replication (enzyme: telomerase)
14
Q
Locus?
A
specific location on the chromosome that a gene is located
15
Q
Heterochromatin?
A
regions of densely packed chromatin on a chromosome where genes are inaccessible and turned off
16
Q
Euchromatin?
A
loosely packed chromatin on a chromosome that allow genes to be activated
17
Q
If a retrovirus inserts is genome into regions of heterochromatin and nowhere else, how is this likely to affect the infection process?
A
the retroviral genes will not be expressed very frequently, the virus will remain as a provirus until a change happens
18
Q
Role of the nuclear matrix?
A
support and provide overall structure
regulating gene expression
19
Q
Nucleolus function?
A
functions as a ribosome factory, contains loops of DNA, RNA polymerases, rRNA, and protein components of the ribosome (no membrane separating it from the nucleus)
20
Q
The nucleolus is larger in cells that do what?
A
producing large amounts of proteins due to the increased synthesis of ribosomes
21
Q
What role do the loops of DNA in the nucleolus play?
A
the DNA serves as a template for rRNA production RNA pol
22
Q
Where do the protein components of the ribosome come from during rRNA production?
A
they are transported into the nucleus from the cytoplasm because proteins are translated outside the nucleus
23
Q
Does the ribosome finish assembly in the nucleus?
A
no it remains partially assembled and inactive until it gets to the cytoplasm, this is to prevent translation of hnRNA
24
Q
What is the nuclear membrane?
A
membrane that separates the nucleus from the cytoplasm composed of two lipid bilayers
25
What is the space between the inner and outer nuclear membranes contiguous with?
ER lumen, isolated from the cytoplasm
26
What size of molecule can diffuse through nuclear pores?
molecules smaller than 60 kilodaltons, including small proteins
27
How can larger proteins get inside the nucleus?
they need to contain a sequence called the nuclear localization sequence which are translated on cytoplasmic ribosomes and then imported into the nucleus by a specific transport mechanism
28
Where is the site of oxidative phosphorylation?
mitochondria
29
What is the interior of the mitochondria called?
matrix
30
What does the matrix contain that is important to cell respiration?
pyruvate dehydrogenase and enzymes for the Krebs cycle
31
The inner membrane of the mitochondria is the location for what?
electron transport chain and ATP synthase
site for the proton gradient used to drive ATP synthesis
32
The inner membrane of the mitochondria is folded into what?
cristae
33
The inner of the mitochondria is impermeable to what?
free diffusion of polar substances like protons
34
The outer membrane of the mitochondria is smooth and allows diffusion of what?
has large pores that allow diffusion of small molecules
35
ATP produced in the mitochondria goes where?
transported into the cytoplasm to drive a great variety of cell processes
36
Why is the inner membrane folded into cristae?
to increase surface area of the inner membrane in order to increase electron transport and ATP synthesis
37
Are the enzymes of glycolysis found in the matrix?
no in the cytoplasm
38
How does pyruvate get into the matrix where pyruvate dehydrogenase is located?
transported through the membrane by a specific protein in the membrane
39
Mitochondria possesses their own _____.
genome
40
What is the mitochondria genome like?
smaller than the cell genome and consists of single circular DNA molecule
41
What does the mitochondria genome code for?
rRNA, tRNA, and several proteins including some components of the electron transport chain and parts of the ATP synthase complex (most are coded by nuclear genes)
42
T/F
| Mitochondria use the same system of transcription and translation as the nucleus does.
False
| they have their own
43
What is the mitochondria endosymbiotic theory?
originated as independent unicellular organisms living within larger cells
44
What bacteria do mitochondria resemble?
Gram negative bacteria
45
What difficulty may be encountered in translation of a mitochondrial gene moved to the nucleus?
coding system of cellular genome is different from that of the mitochondrial genome
46
Mitochondria are inherited _______.
maternally
47
Why is the mitochondria inherited maternally?
the cytoplasm of the egg becomes the cytoplasm of the zygote, sperm only contributes nuclear genes
48
If a woman has a disease caused by an abnormality in her mitochondrial genome, what are the chances her children will have the disease?
100%
49
Why is the rough ER called rough?
large number of ribosomes bound to its surface
50
The rough ER is the site for what?
protein synthesis for proteins targeted to enter the secretory pathway, directs protein traffic to different parts of the cell
51
The smooth ER can contain enzymes for what?
involved in steroid hormone biosynthesis (gonads) or in the degradation of environmental toxins (liver)
52
What are the two sites of protein synthesis in Euk cells?
ribosomes free in cytoplasm
ribosomes in rough ER
53
Where do proteins translated by ribosomes in the cytoplasm end up?
peroxisomes, mitochondria, nucleus, cytoplasm
54
Where do proteins translated by ribosomes on the rough ER end up?
1. secreted into extracellular environment
2. integral plasma membrane proteins
3. membrane or interior of the ER, Golgi, or lysosomes
55
The ER, Golgi, lysosomes, and the extracellular environment are essentially _______.
contiguous
56
When a protein ends up in the ER lumen, does it ever touch the cytoplasm before leaving the cell?
no, it is transported on vessicles through the golgi and is let outside the cell by exocytosis
57
What determines whether a protein will be translated on the rough ER?
the sequence of the protein itself, signal sequence at the N-terminus
58
What recognizes the signal sequence in proteins?
signal recognition particle (SRP), which binds to the ribosome
59
The mRNA for a secreted protein encodes a longer protein than is actually observed in the cell exterior. why?
the signal sequence of the protein was removed in the rough ER
the only way a protein can be smaller from its mRNA would be if some post translational modification happened
60
What are transmembrane domains?
sections of integral membrane proteins of hydrophobic amino acid residues that pass through lipid bilayer membranes
61
T/F
| Transmembrane domains are translated and transported the same way as secreted protein.
true
| from ER to golgi to plasma membrane but they are used in the membrane, not secreted
62
For a protein in the plasma membrane, does the portion of the protein in the ER lumen end up facing the cytoplasm or the cell exterior?
cell exterior
63
Glycosylation? where does it occur?
addition of saccharides to proteins
usually occurs in the golgi, but some occurs in the rough ER
64
What is the default target for proteins that go through secretory paths?
plasma membrane
65
What is needed if a protein going through the secretory path needs to end up somewhere other than the plasma membrane?
targeting signal
66
What is needed if a protein that is made in the cytoplasm needs to be sent to an organelle that is not part of the secretory path?
localization signal
67
for more info check out page 146
MCAT bio book
68
Disulfide bridges are found in extracellular proteins because the cytoplasm is a reducing environment that changes cysteine to two cysteines, would it make sense that disulfide bridges are formed in the ER lumen?
yes because the ER lumen is contiguous with the extracellular environment
69
Three functions of the Golgi Apparatus?
1. modification of proteins made in the Rough ER, especially the modification of oligosaccharide chains
2. sorting and sending proteins to their correct destinations
3. synthesizes certain macromolecules (polysaccharides) to be secreted
70
The vesicle traffic to and from the Golgi is mostly ________. (direction?)
unidirectional
71
Retrograde traffic?
proteins that are supposed to be in the ER escape and must be returned to ER from the Golgi (example of traffic not being unidirectional in Golgi)
72
Part of the Golgi nearest the rough ER is the ____ stack, the part farthest from the rough ER is the ___ stack.
cis
Medial is in the middle
trans
73
If vesicle fusion with the Cis Golgi was inhibited, could plasma membrane proteins reach the surface?
no, it must follow a track (ER to Cis to Medial to Trans to cell surface)
74
Constitutive secretory pathway in golgi?
proteins sent in vesicles from the golgi immediately to the cell surface continuously and unregulated
75
Regulated secretory pathway in golgi?
specialized secretory cells store proteins in vesicles and release them only at certain times usually in response to a change (ex. pancreatic cells, B cells)
76
Where are lysosome proteins made, modified, and released?
made- rough ER
modified- Golgi
released- trans Golgi
77
Autophagy?
organelles such as mitochondria that have been damaged or are no longer functional are degraded in lysosomes (self eating)
78
Phagocytosis?
large matter merge with lysosomes which degrade it (ex. macrophages engulf bacteria or viruses)
79
Crinophagy?
lysosomal digestion of unneeded (excess) secretory products
80
What is the enzyme responsible for degradation in lysosomes?
acid hydrolases
81
What is the pH of the cytoplasm and lysosomes?
cyto- 7.4
lyso- 5
82
Can the cell be destroyed in one lysosome ruptures?
no because the acid can be diluted by the cytoplasm, but if many rupture the cell can be destroyed
83
What is the byproduct of enzymes in the peroxisomes? what is it used for?
H2O2
- essential for lipid breakdown
- in liver, essential for detox of drugs and chemicals
84
Even though H2O2 is a dangerous chemical, how do peroxisomes make it not harm the body?
contain an enzyme called catalase which converts it to H2O + O2 which protects against peroxides or free radicals
85
What are the three most common lipids in Euk membranes?
phospholipids (most)
glycolipids
cholesterol
86
What is a distinct feature about phospholipids and glycolipids?
they are hydrophobic and hydrophilic
87
What happens when phospholipids are mixed with water?
they arrange themselves so the hydrophobic tails are facing the interior away from the water and hydrophilic regions are facing outward to interact with water (lipid membranes)
88
What happens when fatty acids are mixed with water?
micelles form (circle)
89
Does the formation of lipid bilayer when phospholipids are mixed with water have a positive or negative delta G?
negative because it forms spontaneously, as the lowest energy state, without external energy input
90
Why cant hydophilic molecules such as ions, carbs, and amino acids barred from passage into the cell?
the inside is hydrophobic, water is excluded, so these molecules are not soluble in this environment
91
What molecules can pass the lipid bilayer easily?
nonpolar molecules such as CO2, O2, and steroid hormones, water passes through specialized channels
92
Another component of the lipid bilayer is ______.
proteins
93
What do proteins do in the lipid bilayer?
- mediate interactions between cells
- cell surface receptors bind extracellular signaling molecules such as hormones and relay signals into the cell
- channel proteins selectively allow ions or molecules to cross the membrane
94
Integral vs peripheral proteins?
I- embedded in the membrane, held by hydrophobic interactions
P- not embedded but are stuck to integral proteins, held by H-bonds and and electrostatic interactions
95
Transmembrane proteins?
cross the whole lipid bilayer
96
At which point in the secretory pathway would the insertion of transmembrane domains into the membrane occur?
in the rough ER as the protein is translated and threaded across the ER membrane
97
Fluid mosaic model?
current understanding of membrane dynamics, membrane is seen as a mosaic of lipids and proteins which are free to move back and forth fluidly, two dimensions
98
Why does the cell membrane have polarity?
lipids and proteins are not free to flip flop
hydrophilic proteins cannot enter the hydrophobic interior
99
What is the exception to the fluid mosaic model?
some proteins are anchored to the cytoskeleton and cannot move
100
What is a major determinant of membrane fluidity?
hydrophobic van der waals interactions between the fatty acid side chains
101
What is the difference between saturated and unsaturated fatty acids in the membrane?
sat- lack double bonds, have a very straight structure and pack tightly in the membrane, strong van der waals
unsat- one or more double bonds, kinked structure and pack in the membrane interior more loosely
102
How does cholesterol play a role in membrane fluidity?
maintains optimal membrane fluidity by fitting into the membrane interior
103
If the % of unsaturated fatty acids in a membrane is increased, will membrane fluidity increase or decrease at body temp?
increase because of kinked structure and weaker van der waals
104
Which proteins transport materials through membranes that cannot diffuse on their own?
integral membrane proteins
105
Diffusion?
solute moves from high to low concentration
106
Osmosis?
solvent diffuses instead of solute
107
What will happen to the cell if it is placed in a hypotonic solution?
swell and burst
108
What will happen to the cell if it is placed in a hypertonic solution?
shrink
109
Isotonic?
solute concentration is the same inside and outside the cell
110
Osmotic pressure?
force required to resist the movement of water by osmosis
if a solution is highly concentrated, it has a strong tendency to draw water into itself, so the pressure required to resist it would be high
111
The greater the difference in tonicity across a semipermeable membrane, _______.
the greater the osmotic pressure
112
What is transport that is any thermodynamically favorable movement of solute across a membrane (down a gradient)?
passive transport (no energy required)
113
What are the two types of passive transport?
simple diffusion
facilitated diffusion
114
Why are steroid hormones free to move back and forth across the membrane?
simple diffusion as pushed by their concentration gradients because of their hydrophobicity
115
Facilitated diffusion?
movement of a solute across a membrane, down a gradient (integral proteins), when the membrane is impermeable to that solute (ex. glucose crossing the membrane into red blood cells)
116
What are the two types of proteins (selective) used in facilitated diffusion?
channel proteins
| carrier proteins
117
What do channel proteins allow passage of?
each channel can only let in one type of ion down the concentration gradient, they are gated, form a tunnel for ions to pass
118
Voltage gated ion channel?
channel that opens in response to a change in the electrical potential across the membrane
119
Ligand gated channel?
opens in response to binding of a specific molecule like a neurotransmitter
120
Can ion channels move ions against an electrochemical gradient?
no, only down due to facilitated diffusion
121
How do carrier proteins move molecules across the membrane?
bind the molecules to be transported at one side of the membrane and undergo conformational change to move the molecule to the other side
122
Uniports? symports? antiports?
uni- transport only one molecule at a time
symp- carry two substances in the same direction
anti- carry two substances in opposite directions
123
Pores in the membrane?
tube through membrane so large that it is not selective and all molecules below a certain size may pass unless they are just small enough and have the wrong charge on its surface
124
What forms pores?
polypeptides called porins
125
What membranes have pores?
nuclear membrane, outer mitochondrial membrane, gram negative bacteria outer membrane
Euk plasma membrane does not have pores
126
Are porins and ion channels found in the same membrane?
no because there would be no use for ion channels if porins were present because they are big enough to let ions in
127
Saturation kinetics?
facilitated diffusion depends on a finite number of integral proteins so increasing the driving force increases the rate of diffusion (flux) but only to a certain point, then all transport proteins become saturated and no further increase is possible (this doesnt happen in simple diffusion)
128
Active transport?
movement of molecules through plasma memrbane against a gradient, requires energy, involves a protein (delta G is negative)
129
What type of energy input is needed for primary active transport?
transport is coupled with ATP hydrolysis
130
What type of energy input is needed for secondary active transport?
transport is not coupled with ATP hydrolysis
ATP is first used to create a gradient, then the potential energy in that gradient is used to drive the actual transport of other molecules across the membrane, ATP is used indirectly, commonly coupled with the flow of sodium ions
131
If a protein moves sodium ions across the plasma membrane down an electrochemical gradient, what form of transport is this?
facilitated diffusion
132
The Na+/K+ ATPase is a ______ protein.
transmembrane
133
The activity provided by the Na+/K+ ATPase is to pump ___ Na+ out of the cell and ____ K+ into the cell, and to hydrolyze ____ ATP to drive the pumping of these ions against their gradients.
3
2
1
134
The pumping of Na and K by the Na+/K+ ATPase is an example of what form of transport?
primary active
135
How do some of the K+ ions pumped into the cell make it back out?
leak out down its gradient by potassium leak channels
136
What is the purpose of potassium leak channels?
maintain osmotic balance with its surroundings
137
As K+ leaves the cell, what happens to the electrical charge on the inside of the cell?
positive charged K+ ions leave, the interior is left with a net negative charge
138
Resting membrane potential?
-70 mV
the potential created by the Na+/K+ ATPase
139
What are the three ways the Na+/K+ ATPase pump is important?
1. maintain osmotic balance between cell interior and exterior
2. establish the resting membrane potential
3. provide the sodium concentration gradient used to drive secondary active transport
140
If an inhibitor of the Na+/K+ ATPase is added to cells, what might occur?
the interior of the cell will become less negatively charged because the job of the pump is to pump out one net positive ion
141
Why is chloride so concentrated outside the cell?
the cell interior has millions of negative charges so the chloride serves to balance the inside and outside of the cell
142
Which are high outside the cell? which are high inside?
| Na+, K+, Cl-, Ca2+
inside- K+
outside- Na+, Cl-, Ca2+
143
Exocytosis? Products released?
process to transport material outside the cell in which a vesicle in the cytoplasm fuses with the plasma membrane, and the contents are expelled to the extracellular space
products released are secreted by the cell, such as hormones and digestive enzymes
144
What are the three type of endocytosis?
1. phagocytosis
2. pinocytosis
3. receptor mediated
145
Pinocytosis (cell drinking)?
uptake of small molecules and extracellular fluid via invagination
146
Receptor mediated endocytosis?
a highly specific cellular uptake mechanism where the molecule must bind to a cell surface receptor found in clathrin coated pit (ex. cells take up cholesterol out of the blood so they dont stick to the walls of arteries)
147
Atherosclerosis?
build up of plaque on the walls of arteries
148
Does clathrin recognize and bind to lipoproteins?
no, clathrin is fibrous protein inside the cell that associates with the receptors that do bind to it
149
Compare and contrast receptor mediated endocytosis and active transport?
both import a particular substance
endocytosis- the substance ends up sealed in an endosome
150
What acts as the key for a given receptor?
specific ligand
151
Signal transduction?
the intracellular process triggered by the binding of ligand to its receptor on the cell surface, which activates a second messenger
152
What are the three main types of cell surface receptors?
1. ligand gated ion channels
2. catalytic receptors
3. G protein linked receptors
153
What is an example of ligand gated ion channel? describe process.
sodium channel on the surface of a muscle cell at the neuromuscular junction
when acetylcholine binds to this receptor, the receptor undergoes a conformational change and becomes an open Na+ channel, this causes a massive influx of sodium down its gradient, depolarizes the cell and muscle contracts
154
What is the role of catalytic receptors?
its like a protein kinase, to covalently attach phosphate groups to proteins which regulates protein activity (ex. insulin receptor-tyrosine kinase)
155
Does a G protein linked receptor directly transduce its signal?
no it needs the aid of a second messenger
156
What is a second messenger?
chemical signal that relays instructions from the cell surface to enzymes in the cytoplasm
157
What is the most important second messenger?
cyclic AMP (cAMP)
158
What does cAMP do?
it is the second messenger of epinephrine and glucagon which causes energy mobilization (glycogen and fat breakdown)
159
What are the 6 steps in G protein mediated signal transduction stimulated by epinephrine?
1. Epinephrine arrives at the cell surface and binds to specific G protein linked receptor
2. cytoplasmic portion of the receptor activates G proteins, causing GDP to dissociate and GTP to bind in its place
3. the activated G proteins diffuse through the membrane and activate adenylyl cyclase
4. Adenylyl cyclase makes cAMP from ATP
5. cAMP activates cAMP dependent protein kinases (cAMP-dPK) in cytoplasm
6. cAMP-dPK phosphorylates certain enzymes, mobilizing energy (enzymes necessary for glycogen breakdown activated)
G here is a stimulatory protein
160
What do inhibitory G proteins do?
inactivate adenylyl cyclase
161
What happens when G protein activate phospholipase C?
increases cytoplasmic Ca2+ levels
162
What provides the animal cell with structural support?
cytoskeleton- also allows movement and transport
163
What types of proteins is the internal cytoskeleton composed of?
microtubules- thickest
intermediate filaments
microfilaments- thinnest
they have quaternary structure
164
The microtubule is a hollow rod composed of what two globular proteins?
alpha tubulin
beta tubulin
(polymerized noncovalently)
they form a alphabeta tubulin dimer, many dimers can stick to form a sheet which rolls into a tube
they can get longer or shorter by adding or removing tubulin monomers
165
Microtubule Organizing Center (MTOC)?
side that cannot elongate because it is anchored
166
Centrioles?
structure composed of a ring of nine microtubule triplets, found in pairs at the MTOC of a cell, they duplicate during cell division and serve as the organizing center for the mitotic spindle
167
Aster?
microtubules that radiate out from the centrioles during mitosis, star shaped
168
Polar fibers?
microtubules connecting the chromosomes to the aster
169
Mitotic Spindle?
the whole assembly of centrioles, aster, and polar fibers
170
Two pieces of evidence that centrioles arent essential in mitosis?
1. plants lack centrioles but still undergo mitosis
| 2. experimenters have removed centrioles from animal cells and mitosis still proceeded
171
Cilia in Euk?
small hairs on the surface which move fluids past the cell surface (ex. mucociliary elevator- respiratory tract cilia sweep mucus)
172
The only human cell which has a flagellum is the _____.
sperm
173
What is the structure of cilia and flagella?
9 + 2 arrangement of microtubules
174
Dynein?
microtubules are bound to their neighbors by this protein which causes movement of filaments past one another
175
Basal body?
cilium and flagellum are anchored to plasma membrane by this protein and it has the same structure of a centriole
176
How are microfilaments formed?
in the cytoplasm form polymerization of the globular protein actin
177
What are microfilaments responsible for?
for gross movements of the entire cell, such as pinching parent cell into two daughter cells and amoeboid movement
178
Amoeboid movement?
changes in the cytoplasmic structure cause cytoplasm and the rest of the cell to flow in one direction
179
What makes intermediate filaments different from micro tubules and microfilaments?
heterogeneous, composed of a wide range of polypeptides, more permanent, resists mechanical stress
180
Epithelium?
layer of cells that form a tight seal, preventing items from freely moving between lumen and body
181
Tight junctions?
occluding, seal the prevents movement of substances across the cell layer, found between epithelial cells lining the intestine and the blood brain barrier
182
Desmosomes?
epithelial cells held tightly together but do not form a complete seal (ex. skin)
183
Gap junctions?
connected by holes that allow ions, amino acids, and carbs but not polypeptides or organelles to flow back and forth between them, allow cytoplasms to mix(ex. heart muscle cells- allow action potentials to pass from one to the other)
184
Apical surface?
surface of the plasma membrane facing the intestinal lumen
185
Basolateral surface?
other side of the cell facing the tissues
186
Will a transmembrane protein inserted into the apical surface of an intestinal epithelial cell diffuse in the plane of the plasma membrane to reach the basolateral surface?
no because tight junctions prevent it from diffusing to the other side
187
How are desmosomes anchored to the plasma membrane?
by a plaque formed by the protein keratin, intermediate filaments attach
188
What happens in the S (synthesis) phase?
cell actively replicates its genome
189
What is the M phase?
includes mitosis and cytokinesis
mitosis- divide cellular components in half
cyto- physical dividing
190
What is between the M and S phases?
G1 and G2 phases
191
What are the gap phases plus the S phase known as?
Interphase
192
The cell spends most of its time in what phase?
interphase
193
What is a cell that is permanently stuck in interphase?
Go
194
The more specialized a cell is, the ____ likely it is to be able to reproduce.
less
must be replenished by stem cells
195
Oncogenes?
mutated genes that induce cancer
196
What would happen if Mitosis began during the S phase before the entire genome is replicated?
the genome would be fragmented and incomplete in each daughter cell
197
What are the 4 phases of Mitosis?
Prophase
Metaphase
Anaphase
Telophase
198
What is the first sign of prophase?
the genome becomes visible after not being visible in interphase
199
At the beginning of prophase, what can be seen?
46 chromosomes
23 pairs
200
Two copies of the chromosome separated by a centromere is a ____ ______.
sister chromatid
201
What are homologous chromosomes?
equivalent but nonidentical and do not come anywhere near each other during mitosis
202
What are other important events that take place during prophase?
nucleolus disappears
spindle and kinetochore appear
centrioles move to opposite ends of the cell (cell has two MTOCs called asters)
203
What is the last step in prophase?
prometaphase- nuclear envelope converts itself into many tiny vesicles
204
What happens in metaphase?
all chromosomes line up at the center forming the metaphase plate, this happens because the kinetochore of each sister chromatid is attached to spindle fibers that attach to the MTOC
205
What happens during Anaphase?
spindle fibers shorten and the centromeres of each sister chromatid pair are pulled apart, the cell elongates and cytokinesis begins with the formation of a cleavage furrow accomplished by a ring of microfilaments encircling the cell and contracting
206
What happens in telophase?
nuclear membrane forms around the bunch of chromosomes at each end of the cell, chromosomes decondense and a nucleolus becomes visible within each new cell, each daughter nucleus has 2n chromosomes
207
What is karyotype?
display of an organism's genome
208
```
Euk chromosomes generally only have one of which of the following?
A. reading frame
B. origins of replication
C. promoter
D. centromere
```
D
if it had more than one centromere, it could be pulled apart at different ends and be torn
209
Retrograde? Anterograde?
Retro- moving backwards
Antero- moving forwards
210
Where are steroid hormones stored in the cell?
they are not stored because they can diffuse through the lipid bilayers at any time
211
What is the order of signals leading to the formation of cAMP?
Epinephrine -> GPCR -> G proteins -> adenylyl cyclase -> cAMP
212
The nuclear membrane is absent in which of the following phases of mitosis?
Anaphase
Telophase
Metaphase
Anaphase
| Metaphase
213
Both the Golgi complex and rough ER contribute to protein modification through all except:
phophorylation
creation of disulfide bridges
glycosylation
creation of peptide bonds
creation of peptide bonds
this occurs during translation, prior to any modification
214
T/F
| Phospholipase C and adenylyl cyclase are examples of enzymes found in lysosomes.
False
215
T/F
| Cytochrome C is located in the inner mitochondrial membrane and undergoes redox reactions.
True
