Exam 4 Flashcards
(184 cards)
1
Q
What kind of cells are involved in sexual reproduction?
A
diploid & haploid cells
2
Q
How does a hydra reproduce?
A
budding
3
Q
Are all offspring genetically identical to the parent?
A
yes
4
Q
Is there any genetic variability in a changing environment? If so, what?
A
yes, mutations
5
Q
If a hydra gets stressed in certain ways, what happens?
A
it goes into sexual reproduction
6
Q
Does a hydra live a longer life or a shorter one when it goes into sexual reproduction?
A
shorter life
7
Q
How are sperm and egg gametes produced?
A
by meiosis
8
Q
Parent cells are ________, while germ cells are ________.
A
diploid; haploid
9
Q
What does fertilization result in?
A
diploid embryo
10
Q
Why is there an advantage in sexual reproduction?
A
because of the separation and recombination or genes
11
Q
How many gametes are the parental pair split into?
A
4 gametes
12
Q
What is the function of gametes?
A
propagate genetic information to next generation
13
Q
What is the function of somatic cells?
A
form body of the organism but they leave no progeny
14
Q
Germ cells (gametes) are responsible for?
A
genetic variability
15
Q
What are the three rounds involved in meiosis?
A
one round of DNA replication followed by two rounds of nuclear division
16
Q
When do duplicated homologous chromosomes pair?
A
meiotic prophase
17
Q
What does “crossing over” occur between?
A
the duplicated maternal and paternal chromosomes in each bivalent
18
Q
What ensures the proper segregation of homologs?
A
chromosome pairing and crossing-over
19
Q
What does the second meiotic division produce?
A
haploid daughter nuclei
20
Q
What is “crossing-over”?
A
DNA exchange from chromosome to chromosome
21
Q
Fertilization constitutes a…
A
complete diploid genome
22
Q
Does DNA replication occur in meiosis 1 & 2?
A
no, it only occurs in meiosis 1
23
Q
What is the difference, in stages, of mitosis and meiosis?
A
mitosis has replication followed by one round of division, meiosis has replication followed by two rounds of division
24
Q
Meiosis generates…
A
four nonidentical haploid nuclei
25
Mitosis produces...
two identical diploid nuclei
26
What is a bivalent?
duplicated maternal and paternal chromosome pair
27
When does "crossing-over" occur?
during meiosis 1
28
What is exchanged between bivalent chromosomes during crossing-over?
pieces of chromosomes
29
Where and what do crossing-over points form?
form a chiasmata between non-sister chromatids in each bivalent
30
What occurs in meiosis 2?
chromatid separation that results in haploid gametes, also realignment and formation of new kinetochores
31
What is the result of meiosis 1?
primary oocyte and polar body 1 (diploid)
32
What is the result of meiosis 2?
secondary oocyte and polar body 2 (haploid)
33
What two aspects of genetic reassortment generate new chromosome combinations?
crossing-over during meiosis 1 and independent assortment of maternal/paternal chromosomes during meiosis 2
34
What is one example of infidelity in chromosome segregation?
nondisjunction
35
What is nondisjunction?
result of failure to separate duplicated chromosomes during meiosis
36
What is an example of nondisjunction?
trisomy 21
37
What is the result of nondisjunction?
aneuploid gametes
38
How are multicellular organisms built?
organized collections of cells
39
What gives a plant cell wall its tensile strength?
cellulose microfibrils
40
What do animal connective tissues consist largely of?
extracellular matrix
41
What provides tensile strength in animal connective tissues?
collagen
42
Do cells organize the collagen they secrete?
yes
43
What proteins couple the matrix outside of a cell to the cytoskeleton inside?
integrins
44
What fills spaces and resist compression?
gels of polysaccharides and proteins
45
What polysaccharides do cell walls contain?
cellulose and pectin
46
How is cellulose microfibril formed?
from a bundle of cellulose molecules
47
What helps direct the deposition of cellulose in the plant cell wall?
microtubules
48
What is cellulose synthetase?
transmembrane enzyme protein complex
49
What does cellulose synthetase do?
1. assembles glucose into cellulose polymers to form microfibrils
2. connected to linear arrays of sub membrane microtubules by connector proteins
50
How is the plant plasma membrane extended?
as glucose is supplied it is added to the membrane
51
What matrix protein provide strength and deformability?
collagen
52
Is collagen soluble?
no, it is very insoluble
53
How is collagen assembled?
1. procollagen precursor protein is synthesized and secreted by the cell
2. protease cleavage outside of cells release collagen molecule
3. collagen molecules self-assemble to form collagen fibrils
54
Can collagen be formed by pro collagen?
no
55
Does the original pro collagen polymerize past the triplet?
no
56
What can incorrect collagen assembly cause?
skin to be hyperextensible
57
Fibronectin proteins do what?
bind collagen fibrils outside cells and also bind to integral proteins on plasma membranes
58
How do integrins transmit tension across the plasma membrane?
by anchoring to actin filaments in the cell cytoplasm
59
Some integrins bind to _______, but most bind to ________.
intermediate filaments; actin filaments
60
What happens if there is a fibronectin defect?
cells won't attach and will migrate for forever waiting for the fibronectin signal
61
Epithelial sheets are polarized and rest on what?
the basal lamina
62
What are the two surfaces of epithelial cells?
apical and basal
63
Which of the two surface of an epithelial cell is free?
apical surface
64
What is the basal lamina composed of?
collagen, elastin, fibronectin, etc.
65
What polarized cell types make up the epithelial lining of the intestine?
absorptive cells and goblet cells
66
Describe absorptive cells.
take up nutrients
contain microvilli which increases surface area of plasma membrane for transport of molecules
67
Describe goblet cells.
secrete mucus
contain secretory vesicles loaded with mucus
68
What kind of tissue type is the basal lamina?
connective tissue
69
What makes the epithelium leak proof and separates its apical and basolateral surfaces?
tight junctions
70
Tight junctions in the epithelium only allow for what?
the selective transport of desirable molecules
71
Epithelial cell tight junctions allow what to serve as barriers to molecular diffusion?
cell sheets
72
What are claudin and occludin proteins?
plasma membrane proteins that span the membranes of interacting cells and seal tight junctions
73
Where are claudins and occuldins synthesized?
rough ER
74
Are claudins and occludins glycoproteins?
no because they form really tight junctions and are very exclusionary
75
Cytoskeleton-linked junctions bind epithelial cells to what?
robustly to one another and to the basal lamina
76
Describe tight junctions.
seals neighboring cells together in epithelial sheet to prevent leakage of molecules between them and helps polarize cells
77
Describe adherens junctions.
joins actin bundle in one cell to a similar bundle in a neighboring cell
78
Describe desmosomes.
joins intermediate filaments in one cell to those in a neighbor
79
Describe gap junctions.
form channels that allow small, intracellular, water-soluble molecules to pass from cell to cell
80
Describe hemidesmosomes.
anchors intermediate filaments in a cell to the basal lamina
81
What is the result of adherens junctions?
have actin filaments that go across cells like a band
82
How do hemidesmosomes bind?
through receptors
83
What is formed around epithelial cells in the small intestines?
adhesion belts
84
How are contractile bundles of actin filaments linked to adjacent cells?
by transmembrane cadherins
85
Where do contractile bundles of actin filaments run?
along cytoplasmic surface of plasma membrane near cell apex
86
What are signals for cell cell contact sites?
cadherins
87
What kind of proteins are cadherin proteins?
plasma membrane proteins
88
What happens when a cadherin mutates?
lowers the chances of forming bundles drastically
89
What do cadherin proteins attach to?
actin or keratin intermediate filaments via linker proteins
90
Cadherins concentrate at points of cell cell attachment to form...
adherens junctions
91
How do cadherins recruit linker proteins that dictate actin formation?
through interaction
92
How do epithelial sheets form epithelial tubes?
they bend
93
What are examples of epithelial sheets forming epithelial tubes?
neural tube formation during development
formation of eye cup and pinched off lens vesicle
94
Desmosomes link what of one epithelial cell to those of another?
keratin intermediate filaments
95
What anchors keratin filaments in an epithelial cell to the basal lamina?
hemidesmosomes
96
Is linkage in hemidesmosomes mediate by integrin or cadherin proteins?
integrin
97
What binds keratin filaments to integrin proteins?
plaques of linker proteins
98
Where do plaques form in hemidesmosomes?
at the touch points
99
Do hemidesmosomes interact with extracellular matrix?
yes
100
What do gap junctions allow to pass from cell to cell?
inorganic and small molecules
101
What do gap junctions provide for neighboring cells?
with a direct channel of intercystolic communication
102
interacting plasma membranes are penetrated by what complexes that make up gap junctions?
connexon protein complexes
103
What dictates the size of a gap junction?
by formation and structure of the portals
104
Connexon form portals through what?
interactions
105
What regulates the permeability of gap junctions?
extracellular signals
106
Treatment of the retina with what decreases permeability of gap junctions?
dopamine
107
Can many cell types go into making different types of tissues?
yes
108
What is an example of many cell types going into tissues?
the retina
109
Are different tissues renewed at different rates?
yes
110
What generates a continuous supply of terminally differentiated cells?
stem cells and proliferating precursor cells
111
What maintains stem cell populations?
specific signals
112
What can stem cells be used for?
repair lost of damaged tissues
113
What type of stem cells provide a convenient source of human embryonic cells?
induced pluripotent stem cells
114
What can mouse and human pluripotent stems cells form?
organdies in a culture
115
What is the epidermis?
epithelial cells
116
What is the dermis?
connective tissue, loose layer, and dense layer
117
What is the hypodermis?
fatty connective tissue
118
What two layers of skin are casularized and innervated?
dermis and hypodermis
119
What is keratins intermediate filament?
keratocytes
120
What generates the collagen matrix?
fibroblasts
121
What happens when a stem cell divides?
the daughter cells can either remain a stem cell or become terminally differentiated into a defined function
122
Precursor cells slide upward and terminally differentiate into what cells in the process of cell replacement in the epithelial lining of the intestine?
secretory and absorptive cells
123
Where are secretory and absorptive cells shed?
from the tip of the villus
124
Are microvilli and villi the same thing?
no
125
Collagen is a major protein of what?
the basal lamina
126
Cells attach to what by integrin in cell replacement in the epithelial lining of the intestine.
fibronectin
127
What kind of epithelium is renewed from stem cells in the basal layer?
stratified
128
Cells undergo programmed cell death leaving what packed with keratin intermediate filaments that are ultimately shed?
flattened scales
129
Does blood contain many circulating cell types?
yes
130
Blood is derived from what?
a single type of stem cell in the bone marrow
131
Hemopoietic stem cells divide to do what?
generate more stem cells and various types of precursor cells
132
Precursor cells divide and differentiate into what found in the circulation?
mature blood cell types
133
What does the Wnt signal pathway do in the intestinal crypt?
maintains proliferation of the stem cells and precursor cells
134
What happens in the absence of Wnt?
cells stop mitosis and proliferation and differentiate to final cell types
135
What do you have to stop in order to go into differentiation in the intestinal crypt?
mitosis
136
When there is no Wnt what happens?
they go down the pathways of their differentiations
137
Wnt signaling pathways controls the degradation of what?
beta catenin
138
What does beta catenin control?
transcription
139
What protein keeps the Wnt signaling pathway inactive in the absence of Wnt?
APC
140
When Wnt is active, APC is inactive which releases what?
active beta catenin
141
Mutations in APC initiate what?
tumors
142
Does beta catenin ever reach a threshold?
no
143
Mouse Es are harvested from the inner cell mass of the embryo during what stage of development in the culture?
blastocyst stage
144
Treatment with what of the Mouse ES induced differentiation into specific cell types?
different signaling
145
What are pluripotent stem cells?
cells that have the ability to undergo self renewal and give rise to all cells of the tissues of the body
146
Can pluripotent cells be deprogrammed and made into embryonic stem cells?
yes
147
Can embryonic stem cells be differentiated into any cell of the body?
yes
148
What happens to human pluripotent cells in a culture?
proliferate, differentiate, and self assemble into tissues
149
What is the eye cup and example of?
3D, multilayered, retina with similar organization to normal eye during development
150
What do cancer cells do?
proliferate excessively and migrate inappropriately
151
Do cancer cells exhibit contact inhibition?
no
152
How does cancer develop?
by accumulation of somatic mutations
153
What are the two main classes of genes that are critical for cancer?
oncogenes and tumor suppressor genes
154
Do cancer critical mutations cluster in one or a few fundamental pathways?
a few
155
Oncogenes are what in the genes which can cause cancer?
single mutations
156
What do tumor suppressors do?
suppress cell growth
157
Are cadherins distributed throughout the cells?
yes
158
What are cadherins important for?
the formation of cell junctions
159
What are cell cell contact issues due to?
cadherins
160
What is Wnt?
a ligand for GPCR receptor
161
Wnt controls beta catenin levels through...
APC proteolysis
162
Cadherins form cell cell adhesions and bind beta catenin which controls what?
free beta catenin levels
163
What are the multiple steps in processing encompassing of metastasis?
1. infiltration of tumor cells into the adjacent tissue (intravascular system)
2. migration of cancer cells into vessels known as intravasation
3. survival into circulatory system
4. extravasation, entry into receptive organs
5. proliferation to competent organs
164
Where can cancer cell migrate?
through the basal lamina, blood, or lymphatic vessels
165
What do cancer cells secrete?
matrix metalloproteinases (MMPs) invlved in digesting connective tissues
166
What has a lot to do with the specificity of targeted secondary sites?
integrin expression and mutations
167
What are the common sites of lung cancer metastases?
bones, liver, brain, lymph nodes, adrenal glands
168
What is colon cancer a function of?
aging
169
What are the factors that can contribute to genetic instability?
1. defects in DNA replication
2. defects in DNA repair
3. defects in cell cycle checkpoints
4. mistakes in mitosis
5. abnormal chromsome numbers
170
What is genetic instability the result of?
failed cell cycled regulatory checkpoints and mitosis
171
Breast cancer karyotypes show what?
multiple chromosome translocations
172
What happens to cancer cells over time due to mutations?
become more aggressive and less responsive
173
How do tumors evolve?
repeated rounds o mutation, proliferation, and natural selection
174
What becomes a dominant clone in the tumor?
daughter cell progeny
175
Mutations in what are dominant?
proto-oncogenes
176
Mutations in single gene copy induces what?
cell proliferation and cancer
177
Are mutations in tumor suppressor genes dominant or recessive?
recessive
178
What in a single copy of the proto-oncogene can drive a cell towards cancer?
gain of function mutation
179
In a tumor suppressor gene both copies of the gene must what in order to drive the cell towards cancer?
lose function
180
What converts proto-oncogenes to oncogenes?
gain of function mutations
181
Both copies of a tumor suppressor gene must be lost in order to...
eliminate tumor suppressor function
182
What are the key regulatory pathways perturbed in most human cancers?
1. alterations in cell proliferation
2. alterations in DNA damage response
3. alterations in cell growth
4. alterations in cell survival
183
Can years pass before tumors become noticeable>
yes
184
Typical treat tumor doubles cell number how often?
about every 100 days
