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Cell Biology > Exam 4 > Flashcards

Exam 4 Flashcards

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1
Q

What kind of cells are involved in sexual reproduction?

A

diploid & haploid cells

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2
Q

How does a hydra reproduce?

A

budding

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3
Q

Are all offspring genetically identical to the parent?

A

yes

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4
Q

Is there any genetic variability in a changing environment? If so, what?

A

yes, mutations

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5
Q

If a hydra gets stressed in certain ways, what happens?

A

it goes into sexual reproduction

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6
Q

Does a hydra live a longer life or a shorter one when it goes into sexual reproduction?

A

shorter life

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7
Q

How are sperm and egg gametes produced?

A

by meiosis

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8
Q

Parent cells are ________, while germ cells are ________.

A

diploid; haploid

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9
Q

What does fertilization result in?

A

diploid embryo

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10
Q

Why is there an advantage in sexual reproduction?

A

because of the separation and recombination or genes

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11
Q

How many gametes are the parental pair split into?

A

4 gametes

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12
Q

What is the function of gametes?

A

propagate genetic information to next generation

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13
Q

What is the function of somatic cells?

A

form body of the organism but they leave no progeny

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14
Q

Germ cells (gametes) are responsible for?

A

genetic variability

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15
Q

What are the three rounds involved in meiosis?

A

one round of DNA replication followed by two rounds of nuclear division

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16
Q

When do duplicated homologous chromosomes pair?

A

meiotic prophase

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17
Q

What does “crossing over” occur between?

A

the duplicated maternal and paternal chromosomes in each bivalent

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18
Q

What ensures the proper segregation of homologs?

A

chromosome pairing and crossing-over

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19
Q

What does the second meiotic division produce?

A

haploid daughter nuclei

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20
Q

What is “crossing-over”?

A

DNA exchange from chromosome to chromosome

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21
Q

Fertilization constitutes a…

A

complete diploid genome

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22
Q

Does DNA replication occur in meiosis 1 & 2?

A

no, it only occurs in meiosis 1

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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

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24
Q

Meiosis generates…

A

four nonidentical haploid nuclei

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25
Q

Mitosis produces…

A

two identical diploid nuclei

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26
Q

What is a bivalent?

A

duplicated maternal and paternal chromosome pair

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27
Q

When does “crossing-over” occur?

A

during meiosis 1

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28
Q

What is exchanged between bivalent chromosomes during crossing-over?

A

pieces of chromosomes

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29
Q

Where and what do crossing-over points form?

A

form a chiasmata between non-sister chromatids in each bivalent

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30
Q

What occurs in meiosis 2?

A

chromatid separation that results in haploid gametes, also realignment and formation of new kinetochores

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31
Q

What is the result of meiosis 1?

A

primary oocyte and polar body 1 (diploid)

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32
Q

What is the result of meiosis 2?

A

secondary oocyte and polar body 2 (haploid)

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33
Q

What two aspects of genetic reassortment generate new chromosome combinations?

A

crossing-over during meiosis 1 and independent assortment of maternal/paternal chromosomes during meiosis 2

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34
Q

What is one example of infidelity in chromosome segregation?

A

nondisjunction

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35
Q

What is nondisjunction?

A

result of failure to separate duplicated chromosomes during meiosis

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36
Q

What is an example of nondisjunction?

A

trisomy 21

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37
Q

What is the result of nondisjunction?

A

aneuploid gametes

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38
Q

How are multicellular organisms built?

A

organized collections of cells

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39
Q

What gives a plant cell wall its tensile strength?

A

cellulose microfibrils

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40
Q

What do animal connective tissues consist largely of?

A

extracellular matrix

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41
Q

What provides tensile strength in animal connective tissues?

A

collagen

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42
Q

Do cells organize the collagen they secrete?

A

yes

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43
Q

What proteins couple the matrix outside of a cell to the cytoskeleton inside?

A

integrins

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44
Q

What fills spaces and resist compression?

A

gels of polysaccharides and proteins

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45
Q

What polysaccharides do cell walls contain?

A

cellulose and pectin

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46
Q

How is cellulose microfibril formed?

A

from a bundle of cellulose molecules

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47
Q

What helps direct the deposition of cellulose in the plant cell wall?

A

microtubules

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48
Q

What is cellulose synthetase?

A

transmembrane enzyme protein complex

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49
Q

What does cellulose synthetase do?

A
  1. assembles glucose into cellulose polymers to form microfibrils
  2. connected to linear arrays of sub membrane microtubules by connector proteins
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50
Q

How is the plant plasma membrane extended?

A

as glucose is supplied it is added to the membrane

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51
Q

What matrix protein provide strength and deformability?

A

collagen

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52
Q

Is collagen soluble?

A

no, it is very insoluble

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53
Q

How is collagen assembled?

A
  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
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54
Q

Can collagen be formed by pro collagen?

A

no

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55
Q

Does the original pro collagen polymerize past the triplet?

A

no

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56
Q

What can incorrect collagen assembly cause?

A

skin to be hyperextensible

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57
Q

Fibronectin proteins do what?

A

bind collagen fibrils outside cells and also bind to integral proteins on plasma membranes

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58
Q

How do integrins transmit tension across the plasma membrane?

A

by anchoring to actin filaments in the cell cytoplasm

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59
Q

Some integrins bind to _______, but most bind to ________.

A

intermediate filaments; actin filaments

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60
Q

What happens if there is a fibronectin defect?

A

cells won’t attach and will migrate for forever waiting for the fibronectin signal

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61
Q

Epithelial sheets are polarized and rest on what?

A

the basal lamina

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62
Q

What are the two surfaces of epithelial cells?

A

apical and basal

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63
Q

Which of the two surface of an epithelial cell is free?

A

apical surface

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64
Q

What is the basal lamina composed of?

A

collagen, elastin, fibronectin, etc.

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65
Q

What polarized cell types make up the epithelial lining of the intestine?

A

absorptive cells and goblet cells

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66
Q

Describe absorptive cells.

A

take up nutrients
contain microvilli which increases surface area of plasma membrane for transport of molecules

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67
Q

Describe goblet cells.

A

secrete mucus
contain secretory vesicles loaded with mucus

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68
Q

What kind of tissue type is the basal lamina?

A

connective tissue

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69
Q

What makes the epithelium leak proof and separates its apical and basolateral surfaces?

A

tight junctions

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70
Q

Tight junctions in the epithelium only allow for what?

A

the selective transport of desirable molecules

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71
Q

Epithelial cell tight junctions allow what to serve as barriers to molecular diffusion?

A

cell sheets

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72
Q

What are claudin and occludin proteins?

A

plasma membrane proteins that span the membranes of interacting cells and seal tight junctions

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73
Q

Where are claudins and occuldins synthesized?

A

rough ER

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74
Q

Are claudins and occludins glycoproteins?

A

no because they form really tight junctions and are very exclusionary

75
Q

Cytoskeleton-linked junctions bind epithelial cells to what?

A

robustly to one another and to the basal lamina

76
Q

Describe tight junctions.

A

seals neighboring cells together in epithelial sheet to prevent leakage of molecules between them and helps polarize cells

77
Q

Describe adherens junctions.

A

joins actin bundle in one cell to a similar bundle in a neighboring cell

78
Q

Describe desmosomes.

A

joins intermediate filaments in one cell to those in a neighbor

79
Q

Describe gap junctions.

A

form channels that allow small, intracellular, water-soluble molecules to pass from cell to cell

80
Q

Describe hemidesmosomes.

A

anchors intermediate filaments in a cell to the basal lamina

81
Q

What is the result of adherens junctions?

A

have actin filaments that go across cells like a band

82
Q

How do hemidesmosomes bind?

A

through receptors

83
Q

What is formed around epithelial cells in the small intestines?

A

adhesion belts

84
Q

How are contractile bundles of actin filaments linked to adjacent cells?

A

by transmembrane cadherins

85
Q

Where do contractile bundles of actin filaments run?

A

along cytoplasmic surface of plasma membrane near cell apex

86
Q

What are signals for cell cell contact sites?

A

cadherins

87
Q

What kind of proteins are cadherin proteins?

A

plasma membrane proteins

88
Q

What happens when a cadherin mutates?

A

lowers the chances of forming bundles drastically

89
Q

What do cadherin proteins attach to?

A

actin or keratin intermediate filaments via linker proteins

90
Q

Cadherins concentrate at points of cell cell attachment to form…

A

adherens junctions

91
Q

How do cadherins recruit linker proteins that dictate actin formation?

A

through interaction

92
Q

How do epithelial sheets form epithelial tubes?

A

they bend

93
Q

What are examples of epithelial sheets forming epithelial tubes?

A

neural tube formation during development
formation of eye cup and pinched off lens vesicle

94
Q

Desmosomes link what of one epithelial cell to those of another?

A

keratin intermediate filaments

95
Q

What anchors keratin filaments in an epithelial cell to the basal lamina?

A

hemidesmosomes

96
Q

Is linkage in hemidesmosomes mediate by integrin or cadherin proteins?

A

integrin

97
Q

What binds keratin filaments to integrin proteins?

A

plaques of linker proteins

98
Q

Where do plaques form in hemidesmosomes?

A

at the touch points

99
Q

Do hemidesmosomes interact with extracellular matrix?

A

yes

100
Q

What do gap junctions allow to pass from cell to cell?

A

inorganic and small molecules

101
Q

What do gap junctions provide for neighboring cells?

A

with a direct channel of intercystolic communication

102
Q

interacting plasma membranes are penetrated by what complexes that make up gap junctions?

A

connexon protein complexes

103
Q

What dictates the size of a gap junction?

A

by formation and structure of the portals

104
Q

Connexon form portals through what?

A

interactions

105
Q

What regulates the permeability of gap junctions?

A

extracellular signals

106
Q

Treatment of the retina with what decreases permeability of gap junctions?

A

dopamine

107
Q

Can many cell types go into making different types of tissues?

A

yes

108
Q

What is an example of many cell types going into tissues?

A

the retina

109
Q

Are different tissues renewed at different rates?

A

yes

110
Q

What generates a continuous supply of terminally differentiated cells?

A

stem cells and proliferating precursor cells

111
Q

What maintains stem cell populations?

A

specific signals

112
Q

What can stem cells be used for?

A

repair lost of damaged tissues

113
Q

What type of stem cells provide a convenient source of human embryonic cells?

A

induced pluripotent stem cells

114
Q

What can mouse and human pluripotent stems cells form?

A

organdies in a culture

115
Q

What is the epidermis?

A

epithelial cells

116
Q

What is the dermis?

A

connective tissue, loose layer, and dense layer

117
Q

What is the hypodermis?

A

fatty connective tissue

118
Q

What two layers of skin are casularized and innervated?

A

dermis and hypodermis

119
Q

What is keratins intermediate filament?

A

keratocytes

120
Q

What generates the collagen matrix?

A

fibroblasts

121
Q

What happens when a stem cell divides?

A

the daughter cells can either remain a stem cell or become terminally differentiated into a defined function

122
Q

Precursor cells slide upward and terminally differentiate into what cells in the process of cell replacement in the epithelial lining of the intestine?

A

secretory and absorptive cells

123
Q

Where are secretory and absorptive cells shed?

A

from the tip of the villus

124
Q

Are microvilli and villi the same thing?

A

no

125
Q

Collagen is a major protein of what?

A

the basal lamina

126
Q

Cells attach to what by integrin in cell replacement in the epithelial lining of the intestine.

A

fibronectin

127
Q

What kind of epithelium is renewed from stem cells in the basal layer?

A

stratified

128
Q

Cells undergo programmed cell death leaving what packed with keratin intermediate filaments that are ultimately shed?

A

flattened scales

129
Q

Does blood contain many circulating cell types?

A

yes

130
Q

Blood is derived from what?

A

a single type of stem cell in the bone marrow

131
Q

Hemopoietic stem cells divide to do what?

A

generate more stem cells and various types of precursor cells

132
Q

Precursor cells divide and differentiate into what found in the circulation?

A

mature blood cell types

133
Q

What does the Wnt signal pathway do in the intestinal crypt?

A

maintains proliferation of the stem cells and precursor cells

134
Q

What happens in the absence of Wnt?

A

cells stop mitosis and proliferation and differentiate to final cell types

135
Q

What do you have to stop in order to go into differentiation in the intestinal crypt?

A

mitosis

136
Q

When there is no Wnt what happens?

A

they go down the pathways of their differentiations

137
Q

Wnt signaling pathways controls the degradation of what?

A

beta catenin

138
Q

What does beta catenin control?

A

transcription

139
Q

What protein keeps the Wnt signaling pathway inactive in the absence of Wnt?

A

APC

140
Q

When Wnt is active, APC is inactive which releases what?

A

active beta catenin

141
Q

Mutations in APC initiate what?

A

tumors

142
Q

Does beta catenin ever reach a threshold?

A

no

143
Q

Mouse Es are harvested from the inner cell mass of the embryo during what stage of development in the culture?

A

blastocyst stage

144
Q

Treatment with what of the Mouse ES induced differentiation into specific cell types?

A

different signaling

145
Q

What are pluripotent stem cells?

A

cells that have the ability to undergo self renewal and give rise to all cells of the tissues of the body

146
Q

Can pluripotent cells be deprogrammed and made into embryonic stem cells?

A

yes

147
Q

Can embryonic stem cells be differentiated into any cell of the body?

A

yes

148
Q

What happens to human pluripotent cells in a culture?

A

proliferate, differentiate, and self assemble into tissues

149
Q

What is the eye cup and example of?

A

3D, multilayered, retina with similar organization to normal eye during development

150
Q

What do cancer cells do?

A

proliferate excessively and migrate inappropriately

151
Q

Do cancer cells exhibit contact inhibition?

A

no

152
Q

How does cancer develop?

A

by accumulation of somatic mutations

153
Q

What are the two main classes of genes that are critical for cancer?

A

oncogenes and tumor suppressor genes

154
Q

Do cancer critical mutations cluster in one or a few fundamental pathways?

A

a few

155
Q

Oncogenes are what in the genes which can cause cancer?

A

single mutations

156
Q

What do tumor suppressors do?

A

suppress cell growth

157
Q

Are cadherins distributed throughout the cells?

A

yes

158
Q

What are cadherins important for?

A

the formation of cell junctions

159
Q

What are cell cell contact issues due to?

A

cadherins

160
Q

What is Wnt?

A

a ligand for GPCR receptor

161
Q

Wnt controls beta catenin levels through…

A

APC proteolysis

162
Q

Cadherins form cell cell adhesions and bind beta catenin which controls what?

A

free beta catenin levels

163
Q

What are the multiple steps in processing encompassing of metastasis?

A
  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
Q

Where can cancer cell migrate?

A

through the basal lamina, blood, or lymphatic vessels

165
Q

What do cancer cells secrete?

A

matrix metalloproteinases (MMPs) invlved in digesting connective tissues

166
Q

What has a lot to do with the specificity of targeted secondary sites?

A

integrin expression and mutations

167
Q

What are the common sites of lung cancer metastases?

A

bones, liver, brain, lymph nodes, adrenal glands

168
Q

What is colon cancer a function of?

A

aging

169
Q

What are the factors that can contribute to genetic instability?

A
  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
Q

What is genetic instability the result of?

A

failed cell cycled regulatory checkpoints and mitosis

171
Q

Breast cancer karyotypes show what?

A

multiple chromosome translocations

172
Q

What happens to cancer cells over time due to mutations?

A

become more aggressive and less responsive

173
Q

How do tumors evolve?

A

repeated rounds o mutation, proliferation, and natural selection

174
Q

What becomes a dominant clone in the tumor?

A

daughter cell progeny

175
Q

Mutations in what are dominant?

A

proto-oncogenes

176
Q

Mutations in single gene copy induces what?

A

cell proliferation and cancer

177
Q

Are mutations in tumor suppressor genes dominant or recessive?

A

recessive

178
Q

What in a single copy of the proto-oncogene can drive a cell towards cancer?

A

gain of function mutation

179
Q

In a tumor suppressor gene both copies of the gene must what in order to drive the cell towards cancer?

A

lose function

180
Q

What converts proto-oncogenes to oncogenes?

A

gain of function mutations

181
Q

Both copies of a tumor suppressor gene must be lost in order to…

A

eliminate tumor suppressor function

182
Q

What are the key regulatory pathways perturbed in most human cancers?

A
  1. alterations in cell proliferation
  2. alterations in DNA damage response
  3. alterations in cell growth
  4. alterations in cell survival
183
Q

Can years pass before tumors become noticeable>

A

yes

184
Q

Typical treat tumor doubles cell number how often?

A

about every 100 days

Cell Biology (4 decks)

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