Final Exam Flashcards
(158 cards)
1
Q
The Cell Cycle
A
1 Cell growth and chromosome duplication
2 Chromosome segregation
3 Cell division
into daughter cells
2
Q
Eukaryotic Cell-Cycle Times
Cell Type
Early frog embryo cells
Yeast cells
Mammalian intestinal epithelial cells
Mammalian fibroblasts in culture
A
Cell-Cycle Times
30 minutes
1.5 hours
~12 hours
~20 hours
3
Q
Interphase
A
M Phase - mitosis (nuclear division), cytokinesis (cytoplasmic division)
G1 Phase
S Phase - DNA Replication
G2 Phase
4
Q
Cell Cycle Checkpoint: Enter Mitosis
A
Is all DNA replicated?
Is all DNA damage repaired?
5
Q
Cell Cycle Checkpoint: Pull Duplicated Chromosomes Apart
A
Are all chromosomes properly attached to the mitosis spindle?
6
Q
Cell Cycle Checkpoint: Enter S Phase
A
Is environment favorable?
7
Q
Progression through the cell cycle depends on
A
cyclic- dependent protein kinases
8
Q
The M-cyclin concentration and M-Cdk activity are at a ____ during mitosis and are ______ through interphase
A
high, rising
9
Q
Distinct Cdk’s associate with different cyclins to trigger specific events in the cell cycle
A
and have different concentration and activity graphs
10
Q
The Major Cyclins and Cdks of Vertebrates
Cyclin-Cdk Complex
G1-Cdk
G1\S-Cdk
S-Cdk
M-Cdk
A
Cyclin Cdk Partner
Cyclin D* Cdk4, Cdk6
Cyclin E Cdk2
Cyclin A Cdk2
Cyclin B Cdk1
*there are three D cyclins in mammals (cyclins D1, D2, and D3)
11
Q
Cyclin-dependent kinase activity is often regulated through
A
targeted degradation of cyclin
12
Q
Active cyclin-Cdk complex —1—> Ubiquitin Chain —2—> Inactive Cdk
A
1 Ubiquitylation of cyclin by APC
2 Destruction of cyclin in proteasome
13
Q
For m-Cdk to be active, __________ __________ must be removed
A
inhibitory phosphates
14
Q
Mitotic Cdk —1—> Inactive M-Cdk + Inhibitory Phosphate —2—> Active M-Cdk
A
1 M cyclin, Inhibitory kinase
2 Phosphate Ion, Activating Phosphatase
15
Q
The activity of a Cdk can be blocked by
A
the binding of a Cdk inhibitor
16
Q
Control of the cell cycle: Inhibition of activating phosphatase
A
Blocks entry to mitosis
17
Q
Control of the cell cycle: Inhibition of APC activation
A
Delays exit from mitosis
18
Q
Control of the cell cycle: Cdk inhibitors
A
Block entry to S phase
19
Q
___ ______ can arrest the cell cycle in G1 phase
A
DNA damage (from an X-ray for example)
20
Q
The initiation of DNA replication takes place in two steps
DNA, Cdc6, ORC (origin recognition complex sitting on origin) —1—> DNA helicase, pre-replicative complex (pre-RC) —2—> S-Cdk, Replication Fork, DNA polymerase —>
A
1 G1, Helicase binds, Cdc6 Dissociates, Orgin Loaded
2 S, Helicase activated, replication machine recruited, Origin Fired
Completion of DNA Replication
21
Q
At mitosis, activated M-Cdk indirectly activated more M-Cdk, creating a
A
positive feedback loop
22
Q
Mitosis is driven by
A
microtubules and associated proteins
23
Q
Sister chromatids separate at
A
anaphase
24
Q
The division of a cell into two daughters occurs in the _ _____ of the cell cycle
A
M phase
25
M phase consists of nuclear division, or _______, and cytoplasmic division, or ___________
mitosis, cytokinesis
26
Stages of the M Phase
Mitosis
1 prophase
2 prometaphase
3 metaphase
4 anaphase
5 telophase
Cytokinesis
27
During __________ , the cell increases in size. The ___ of the chromosomes is replicates, and the __________ is duplicated.
interphase, DNA, centrosome
28
Stages of Interphase
G1
S
G2
29
At ________, the duplicated chromosomes, each consisting of two closely associated ______ __________, condense. Outside the nucleus, the _______ _______ assembles between the two ___________, which have begun to move apart.
prophase, sister chromatids, mitotic spindle, centrosomes
30
____________ starts abruptly with the breakdown of the _______ ________. Chromosomes can now attach to _______ ____________ via their ____________ and undergo ______ ________.
Prometaphase, nuclear envelope, spindle microtubules, kinetochores, active movement
31
At _________, the ___________ are aligned at the equator of the spindle, midway between the spindle poles. The ___________ ____________ on each sister chromatid attach to opposite poles
metaphase, chromosomes, kinetochore microtubules
32
At ________, the ______ __________ synchronously separate and are pulled slowly towards the spindle pole to which they are attached. The ___________ ____________ get shorter, and the _______ _____ also move apart, both contributing to chromosome segregation.
anaphase, sister chromatids, kinetochore microtubules, spindle poles
33
During _________, the two sets of chromosomes arrive at the _____ of the spindle. A new _______ ________ reassembles around each set, completing the formation of two ______ and marking the end of _______. The division of the _________ begins with the assembly of the ___________ ____.
telophase, poles, nuclear envelope, nuclei, mitosis, cytoplasm, contractile ring
34
During ___________ of an animal cell, the cytoplasm is divided in two by a contractile ring of _____ and ______ _________, which pinches the cell into ___ _________, each with ___ _______
cytokinesis, actin and myosin filaments, two daughters, one nucleus
35
At metaphase, daughter chromosomes line up at the _______ of the dividing cell.
equator
36
__________ and ________ work together in chromosome condensation
Condensins and cohesins
37
The ____________ plays an essential role in mitosis
cytoskeleton
38
____________ of the mitotic spindle
microtubules
39
_____ and ______ _________ of the contractile ring
actin and myosin filaments
40
___________ are the origin of the microtubule network the comprises the _______ _________
Centrosomes, mitotic apparatus
41
Centrosome
G1
42
Replicated centrosome
G2
43
Aster
Forming mitotic spindle
Duplicated chromosome
Nuclear envelope
Metaphase spindle
M phase
44
Centrioles are replicated during the cell cycle in _ and __ phases
S and G2
45
____________ rearrange and move during chromosome segregation
Microtubules
46
Microtubules attach to chromosomes at the ___________
kinetochore
47
Three classes of microtubules are found in the mitotic apparatus
Aster microtubules
Kinetochore microtubules
Interpolar microtubules
48
___ triggers the separation of sister chromatids by promoting the destruction of ________
APC, cohesins
49
___________ is the last step in cell division
Cytokinesis
50
Multicellular organisms are made up of
organized collections of cells
51
Cells are organized into
tissues
52
In bone and order connective tissue, _____________ ______ is abundant
extracellular matrix
53
In skin and other tissues ________ _______ are organized into bundles
collagen fibrils
54
Procollagen precursors are cleaved to form
mature collagen outside the cell
55
procollagen & secretory vesicle —> secreted procollagen molecule —1—> collagen molecule —2—> collagen fibril
1 proteinase cleaves terminal procollagen extensions
2 self-assembly into fibril
56
Collagen fibrils in skin are arranged in a
plywood-like pattern
57
_______ _______ that result in incorrect collagen assembly in skin can have buzzard consequences
Genetic defects
58
__________ and ________ proteins help attach a cell to the extracellular matrix
Fibronectin and integrin
59
An integrin becomes activated when
it binds to molecules outside of the cell
60
Inactive integrin —1—> strong binding to … —> active integrin
1 binding to extracellular matrix or binding to cytoskeleton
61
Proteoglycans and glycosaminoglycans can form
huge extracellular aggregates
62
Cells can be packed together in different ways to form
epithelial tissues
63
Epithelial tissues
Simple, stratified, columnar, cuboidal, squamous
64
A sheet of epithelial cells has an
apical and a basal surface
65
Apical surface
Free surface
66
Basal surface
Basal lamina
Connective tissue
67
Functionally-polarized cell types line the
intestine
68
________ molecules function to attach one cell to another
Cadherin
69
Adherens junctions form adhesion belts around
epithelial cells in the small intestine
70
Below tight junction
Bundle of actin filaments
Cadherins
Adherens junction
71
___________ ______ can bend to form a tube
Epithelial sheets
72
sheet of epithelial cells —1—> adhesion belt with associated actin filaments —2—> epithelial tube or vesicle
1 invagination of epithelial sheet caused by an organized tightening along adhesion belts in selected regions of cell sheet
2 epithelial tube pinches off from overlying sheet of cells
73
Desmosomes link the
keratin intermediate filaments of one epithelial cell to another
74
Gap junctions provide neighboring cells with a
direct channel of communication
75
seals neighboring cells together in an epithelial sheet to prevent leakage of extracellular molecules between them; helps polarize cells
tight junction
76
Joins an actin bundle in one cell to a similar bundle in a neighboring cell
Adherens junction
77
Joins the intermediate filaments in one cell to those in a neighbor
Desmosome
78
Forms channels that allow small, intracellular, water-soluble molecules, including inorganic ions and metabolites, to pass from cell to cell
Gap junction
79
Anchors intermediate filaments in a cell to the basal lamina
Hemidesmosome
80
___ _____ provide replacement cells for damage repair or renewal of tissues
Stem cells
81
Normally undividing, stem cells can divide and differentiate into specialized cells within the tissue, a process referred to as
Terminal differentiation
82
A terminally differentiated cell normally does not
divide any further
83
The process of recruitment of dormant stem cells into differentiation is controlled by
inter-, intra-, and extra-, cellular signaling pathways
84
Stem cells show promise as investigational tools and as a potential means for
combating genetic disorders
85
Epithelium of
Epidermis
86
Loose connective tissue of
Dermis
87
Dense connective tissue of
Dermis
88
Fatty connective tissue of
Hypodermis
89
Langerhans cell (involved in immune responses)
Pigment cell (melanocyte)
Keratinocytes
Epidermis
90
Macrophage
Collagen fiber
Fibroblast
Endothelial cell forming capillary
Lymphocyte
Loose connective tissue of dermis
91
Fibroblasts
Elastic fiber
Collagen fiber
Dense connective tissue of dermis
92
Stem cells divide to either produce
additional stem cells or terminally differentiated cells
93
In the gut, epithelial stem cells arise in crypts and migrate apically to
repopulate dying epithelial cells
94
The ___ __________ ________ controls the production of differentiated cells in the intestinal crypt
Wnt signaling pathway
95
Wnt pathway active:
Wnt pathway inactive:
Cell proliferation
No cell proliferation
96
In the skin, epithelial cells in the epidermis are renewed from
epithelial stem cells in the basal layer
97
_____ ____ _______________ begins with hematopoietic stem cells located in the bone marrow
Blood cell differentiation
98
T lymphocyte
B lymphocyte
Eosinophil
Basophil
Neutrophil
Monocyte —> osteoclast, macrophage
Megakaryocyte —> platelets
Red blood cells
Hemopoietic stem cell
99
Embryonic stem cells are derived from an embryo and can give rise to
all of the tissues and cell types in the body
100
Induced pluripotent stem cells can be generated by
transformation of cultured cells isolated from adult tissues
101
Culture of fibroblasts from adult skin biopsy —1—> induced pluripotent stem cell —>
1 introduction of DNA encoding three key transcription regulators
Fat cell, neuron, macrophage, heart muscle cell, etc.
102
Cancer is characterized by a loss of normal regulation of cell proliferation, and subsequent invasion of
cancer cells into normal tissues, thus disrupting their function
103
____________ _____________ are common in cancer
Chromosomal abnormalities
104
Genetic changes associated with alterations in cell survival or proliferation can lead to
cancer
105
Gain of function mutation
Dominant mutation
106
Loss of function mutation
Recessive mutation
107
Dominant mutation
Normal cell —1—> activating mutation enables oncogene to stimulate cell survival, proliferation, or both —> excessive cell survival and proliferation
1 mutation in proto-oncogene creates oncogene
108
Recessive mutation
Normal cell —1—> no effect of mutation in one gene copy —2—> two inactivating mutations functionally eliminate the tumor suppressor gene, promoting cell survival and proliferation —> excessive cell survival and proliferation
1 mutation inactivates one copy of tumor suppressor gene
2 second mutation inactivates second gene copy
109
____________ __ _____ __________ _____ can result in the elevated incidence of some cancers
Inactivation of tumor suppressor genes
110
Loss of function mutation in tumor suppressor gene in maternal chromosome + normal tumor suppressor gene in paternal chromosome =
Whole paternal chromosome lost
Region containing normal gene deleted
Loss of function mutation in paternal gene
Gene activity silenced by epigenetic changes
111
(Epithelial cells growing on basal lamina)
A mutation gives one cell an advantage —1—> a second mutation increases the advantage —2—> a third mutation increases the advantage further and makes the cell invasive —3—>
1 cell survival and proliferation
2 cell survival and proliferation
3 dangerous cell survival, proliferation, and invasion
112
Three pathways are altered in almost all human cancers
Alterations in cell proliferation
Alterations in DNA damage response
Alterations in cell growth
113
Six properties required for cells to produce cancer
Loss of regulation of cell proliferation
Loss of susceptibility to programmed cell death
Avoid signaling pathways leading to differentiation
Genetically unstable
Invasiveness
Survival and proliferation in foreign sites
114
Cancer incidence increases with
age
115
All cells require a constant production of
chemical potential energy
116
ATP serves as an energy carrier in cells, as well as a
monomer in cellular DNA
117
Input of energy from sunlight or food —>
Released energy available for intracellular work and for chemical synthesis
118
Subunits —1—> macromolecules —2—> macromolecular assembly
1 covalent bonds
2 noncovalent bonds
119
Most covalent bonds in cells are single, and thus allow
free rotation around the bond
120
Noncovalent interactions (hydrogen bonds and hydrophobic interactions) limit the
possible conformations of macromolecules in the cellular milieu
121
Catabolic and anabolic pathways in metabolism play key roles in
cell metabolism
122
Food molecules —> useful forms of energy + heat lost + the many building blocks for biosynthesis
Catabolic pathways
123
Useful forms of energy + the many building blocks for biosynthesis —> the many molecules that form the cell
Anabolic pathways
124
enzyme, active site + molecule A (substrate) —> enzyme-substrate complex —1—> enzyme-product complex —> enzyme + molecule B (product)
1 catalysis
125
Food molecule, energy —> energetically favorable reaction + inactive carrier —> oxidized food molecule + energy
Catabolism
126
Molecule available in cell —> energetically unfavorable reaction + activated carrier w/ energy —> new molecule needed by cell, energy
Anabolism
127
Activated carrier molecules couple
Catabolism and anabolism
128
Multi-protein complexes act as _________ within cells
factories
129
DNA polymerase synthesizes DNA by adding a
deoxynucleotide to its 3’ end
130
At a replication fork the two DNA strands being replicated are of
opposite polarities
131
Transcription of a eukaryotic gene is initiated by
RNA polymerase II
132
Initiation of transcription —> 5’ RNA capping, elongation, and splicing —> 3’ RNA cleavage, polyadenylation, and termination of transcription —> export —> mRNA degradation —> initiation of protein synthesis (translation) —> completion of protein synthesis and protein folding —> protein degradation
Protein production in eukaryotes
133
______________ __________ can work in a cooperative manner to control gene expression
Transcriptional regulators
134
Stage 1: breakdown of foods to simple subunits
Stage 2: breakdown of simple subunits to acetyl CoA; limited amounts of ATP and NADH produced
Stage 3: complete oxidation of acetyl CoA to H2O and CO2; large amounts of ATP produced in mitochondrion
Stages of cellular metabolism
135
Stage 2 of cellular metabolism
Glycolysis
136
Stage 3 of cellular metabolism
Citric acid cycle
Oxidative phosphorylation
137
Net result of cellular metabolism
ATP, NADH, CO2, H2O
138
This space contains a highly concentrated mixture of hundred of enzymes, including those required for the oxidation of pyruvate and fatty acids and for the citric acid cycle
Mitochondrial matrix
139
Folded into numerous cristae, this proteins that carry out oxidative phosphorylation, including the electron-transport chain and the ATP synthase that makes ATP
Mitochondrial inner membrane
140
This is permeable to all molecules 5000 daltons or less because it contains large channel-forming proteins (called porins)
Mitochondrial outer membrane
141
This space contains several enzymes that use the ATP passing out of the matrix to phosphorylate other nucleotides. It also contains proteins that are released during apoptosis
Mitochondrial intermembrane space
142
High energy electrons are transferred through three protein complexes in the inner mitochondrial membrane
NADH dehydrogenase complex
Cytochrome c reductase complex
Cytochrome c oxidase complex
143
Inside cells many compartments are contained within
membranes
144
Membrane-enclosed organelles import proteins by one of three mechanisms
Transport through nuclear pores
Transport across membranes
Transport by vesicles
145
Extracellular signal molecule —> receptor protein —> intracellular signaling molecules —> effector proteins —> target cell responses
Intracellular signaling pathways can be activated by an extracellular signal molecule
146
Metabolic enzyme, cytoskeletal protein, transcription regulator
Effector proteins
147
Altered metabolism, altered cell shape or movement, altered gene expression
Target cell responses
148
Extracellular signals
Survive, divide, differentiate, die
149
Ion-channel-coupled receptors, G-protein-coupled receptors, enzyme-coupled receptors
Intracellular signaling complexes
150
Intermediate filaments
Ropelike fibers made of fibrous intermediate filament proteins. Give cells mechanical strength and distributes mechanical stress. Very flexible and have great tensile strength. Deform under stress but do not rupture.
151
Microtubules
Hollow cylinders made of the protein tubulin. Long and straight and have one end attached to a centrosome. More rigid, rupture when stretched.
152
Actin filaments
Helical polymers of the protein actin. Flexible. Most highly concentrated in the cortex.
153
Microtubules grow out from an
organizing center
154
Different motor proteins transport different
types of cargo along microtubules
155
Actin filaments allow animal cells to
take on many shapes and have many functions
156
Forces generated by actin filaments in the cortex of the cell drives
cell forward motion
157
___ __________ drives myosin-II filaments along an actin filament
ATP hydrolysis
158
Attached, released, cocked, force-generating, attached
Power stroke
