Module 4 Flashcards
(246 cards)
1
Q
What molecule initiates signal transduction by binding to receptors on the cell membrane?
A
Growth factor
2
Q
Which part of the cell contains receptors that trigger internal signal cascades when activated?
A
Cell membrane
3
Q
What is the role of the cytoskeleton in intracellular signaling and movement?
A
Provides structure and enables transport
4
Q
What type of protein moves along cytoskeleton fibers to help cells move and reorganize?
A
Motor proteins
5
Q
Which organelle does the signal encounter that is responsible for generating the cell’s energy?
A
Mitochondria
6
Q
What does the endoplasmic reticulum (ER) do during protein synthesis in signal response?
A
Synthesizes and transports proteins
7
Q
How does a protein enter the nucleus to influence gene expression?
A
Through nuclear membrane pores
8
Q
What is the function of RNA polymerase in the transcription process?
A
Creates RNA from DNA
9
Q
What molecule carries genetic information from DNA to ribosomes for protein synthesis?
A
Messenger RNA (mRNA)
10
Q
Where does mRNA bind to begin protein assembly based on genetic instructions?
A
Ribosome
11
Q
What process occurs at the ribosome that assembles amino acids into proteins?
A
Translation
12
Q
How do ribosomes enhance efficiency of protein synthesis during translation?
A
Operate simultaneously on the same mRNA
13
Q
What is the function of the Golgi apparatus after proteins are synthesized in the ER?
A
Modifies and packages proteins
14
Q
What cellular structure encloses and transports proteins between organelles or outside the cell?
A
Vesicle
15
Q
How are proteins like growth factors exported from the cell?
A
Vesicle fuses with membrane and releases contents
16
Q
What is the biological role of secreted growth factors in tissue repair?
A
Signal other cells to aid healing and division
17
Q
What step ensures control over signal propagation inside the cytoplasm?
A
Regulated protein activation/deactivation
18
Q
What macromolecule is made by ribosomes using mRNA sequences?
A
Protein
19
Q
Which components act as the “tracks” for motor proteins in a cell?
A
Cytoskeletal fibers
20
Q
What structure wraps DNA and is modified to control gene activity in epigenetics?
A
Histone proteins
21
Q
What is a nucleosome and why is it important in gene regulation?
A
DNA wrapped around histones
22
Q
What do modifications on histone tails influence in the genome?
A
Gene expression (on/off state)
23
Q
What is the term for inheritable changes in gene function not due to DNA sequence?
A
Epigenetics
24
Q
How does DNA methylation affect gene expression?
A
Silences gene by preventing transcription
25
What genetic feature ensures dosage compensation in female mammals?
X chromosome inactivation
26
Why must one X chromosome be inactivated in each female cell?
Prevent overexpression of X-linked genes
27
What physical characteristic distinguishes an inactive X chromosome?
Condensed and transcriptionally silent
28
Which chromatin state allows transcription factors to bind and genes to be expressed?
Open chromatin
29
What enzyme transcribes open DNA into messenger RNA during gene activation?
RNA polymerase
30
When does X chromosome inactivation occur during human development?
At the 100-cell stage in embryo
31
What is passed on during cell division as a result of X inactivation?
Epigenetic memory of inactive X
32
What explains the tortoiseshell coat pattern in female cats at the molecular level?
Random X inactivation
33
What cellular process can go wrong to cause tumor suppressor gene silencing?
Aberrant epigenetic regulation
34
Why is epigenetics critical for cell type-specific gene expression?
Enables selective gene activation or silencing
35
What was the goal of the Genentech somatostatin project in 1977?
Express synthetic hormone gene in bacteria
36
Why was somatostatin chosen as a model for gene synthesis experiments?
Small, well-known sequence, bioactive
37
What organism was engineered to express somatostatin in the 1977 biotech study?
Escherichia coli (E. coli)
38
What genetic control system was used to regulate somatostatin expression in E. coli?
Lac operon
39
Why was cyanogen bromide used after protein expression in the Genentech study?
To cleave precursor at methionine
40
What was the purpose of fusing somatostatin with β-galactosidase in E. coli?
Increase protein stability
41
What type of assay was used to detect somatostatin activity in bacterial extracts?
Radioimmune assay (RIA)
42
What chemical was added to induce gene expression in E. coli under lac control?
IPTG
43
What DNA modification ensures proper fragment insertion into plasmids?
Cohesive ends (Eco RI and Bam HI)
44
What method joined overlapping synthetic DNA fragments into a complete gene?
T4 DNA ligase
45
How did trimer blocks improve the process of DNA synthesis in this experiment?
Increased speed and yield
46
Why were some bacterial clones inactive despite transformation?
Somatostatin gene inserted in wrong orientation
47
What lab technique confirmed insertion of the somatostatin gene into plasmids?
Nucleotide sequencing
48
How was unwanted plasmid self-ligation prevented during cloning?
Alkaline phosphatase treatment
49
Why was most of the somatostatin protein found in the pellet after centrifugation?
It was insoluble
50
What confirmed that bacterial somatostatin matched natural somatostatin in size?
Sephadex G-50 chromatography
51
What genetic feature ensured correct reading frame of the fusion protein?
Link to β-galactosidase gene's coding region
52
What condition was necessary for somatostatin detection in the RIA assay?
Free NH2-terminal alanine
53
What containment level were these experiments conducted under for safety?
P-3 containment
54
What does the success of chemically synthesized gene expression suggest for biotech?
Feasibility of custom gene design
55
How does the skin function as part of the immune system?
Acts as a physical barrier to pathogens
56
Why are mucous membranes part of the first line of immune defense?
They trap and prevent pathogen entry
57
What triggers mast cells to release histamine during inflammation?
Tissue damage
58
What is vasodilation and why does it occur during inflammation?
Widening of blood vessels to increase immune cell access
59
How does histamine increase immune cell access to damaged tissue?
By making blood vessels more permeable
60
How does a macrophage help eliminate pathogens?
Engulfs them through phagocytosis
61
What type of immune cell presents antigens to activate T-helper cells?
Macrophages
62
What do cytotoxic T cells recognize on infected cells to begin their attack?
Presented antigens
63
Why is apoptosis useful in immune defense?
Removes infected cells without spreading pathogens
64
How do helper T cells support both B cells and cytotoxic T cells?
By releasing chemical signals to activate them
65
What is the structural shape of an antibody and why is it important?
Y-shaped; allows specific antigen binding
66
What immune response uses antibodies to block pathogen movement?
Neutralization
67
What does it mean when antibodies "opsonize" a pathogen?
They mark it for phagocytosis
68
Why are memory cells critical to vaccine effectiveness?
They allow a faster, stronger immune response later
69
What is the difference between antibodies and antibiotics?
Antibodies are proteins made by immune cells; antibiotics are drugs
70
How do B cells recognize pathogens?
By binding free-floating antigens
71
What kind of immune cell transforms into a plasma cell to secrete antibodies?
Activated B cell
72
What is the function of a gene in cells?
Provides instructions to make functional molecules
73
What are the two major steps in gene expression?
Transcription and translation
74
What is a polypeptide chain?
A sequence of amino acids made during translation
75
Why do cells regulate gene expression?
To produce only necessary proteins
76
How does the structure of chromatin influence gene expression?
Tightly packed chromatin prevents transcription
77
What is the difference between a promoter and an enhancer?
Promoters initiate transcription; enhancers increase its rate
78
How does DNA methylation suppress gene expression?
It tightens chromatin, blocking transcription factors
79
How do histone acetylation and methylation affect gene accessibility?
Acetylation loosens DNA; methylation usually silences genes
80
What role does RNA polymerase play in gene regulation?
It transcribes DNA into RNA when permitted
81
Why are prokaryotic gene systems often organized into operons?
To regulate multiple related genes at once
82
What does the lac operon do when lactose is absent?
Stays off due to repressor binding
83
How does lactose "turn on" the lac operon?
Binds repressor, causing it to detach from operator
84
What is post-translational regulation in gene expression?
Protein modification after synthesis to affect function
85
Why might a cell degrade mRNA?
To control protein production levels
86
How does the addition of a poly-A tail impact mRNA?
Stabilizes it for translation
87
What is the function of the 5' cap on eukaryotic mRNA?
Protects mRNA and helps ribosome binding
88
What happens if eIF-2 is phosphorylated in translation initiation?
Translation is blocked
89
What is the centromere and what is its function during cell division?
Region linking chromatids; anchors spindle fibers
90
What does a telocentric chromosome look like?
Centromere at end; one long arm
91
What happens if a chromosome loses its telomere?
It degrades and becomes unstable
92
Why do human chromosomes have ~30,000 origins of replication?
To allow timely DNA replication
93
What are autonomously replicating sequences (ARSs)?
Yeast DNA sequences that can initiate replication
94
What structural feature defines a nucleosome?
DNA wrapped around a histone octamer
95
What are the names of the four core histones in nucleosomes?
H2A, H2B, H3, H4
96
What is the function of linker histone H1?
Stabilizes DNA between nucleosomes
97
What is the function of nucleosome tail domains?
Help compact DNA and enable regulation
98
What does the 30 nm chromatin fiber represent?
A compacted form of nucleosome-bound DNA
99
Why is histone H3 so evolutionarily conserved?
Its function is essential and unchanged across species
100
What does DNA looping achieve in transcription regulation?
Brings enhancers near promoters for activation
101
How do nonhistone proteins help regulate chromatin?
They organize loops and assist replication/transcription
102
What is the difference between chromatin and a chromosome?
Chromosome is highly condensed chromatin
103
Why do all cells in a body have the same DNA but different functions?
They express different sets of genes
104
What gene is expressed by liver cells but not neurons?
Alcohol dehydrogenase
105
How does glucagon affect liver gene expression?
Activates transcription of glucose-producing enzymes
106
What prevents PEPCK gene transcription when blood glucose is high?
Insulin represses it
107
Why do neurons express neurexin proteins?
To enable synaptic communication
108
How does chromatin modification control gene access?
Looser chromatin allows transcription; tighter prevents it
109
What is differential gene expression?
Different cells expressing different genes from the same genome
110
What type of regulation ensures only red blood cells express hemoglobin genes?
Tissue-specific transcription factor control
111
What are general transcription factors needed for?
Assembling transcription machinery at promoters
112
What does TFIID bind to during transcription initiation?
TATA box
113
How do enhancer sites affect gene transcription?
They increase it when bound by activators
114
What allows enhancer-bound factors to interact with promoter regions?
DNA looping and mediator proteins
115
What is combinatorial gene regulation?
Multiple transcription factors control one gene
116
Why is transcriptional regulation efficient for the cell?
Prevents unnecessary mRNA synthesis
117
How do environmental factors influence gene expression?
By altering transcription factor activity or epigenetic marks
118
What happens to effective antibody-producing cells after an immune response?
Some become memory cells
119
How do monoclonal antibodies differ from typical immune responses?
They come from a single cell clone; typical responses are polyclonal
120
What was the cloning method used to create Dolly the sheep?
Somatic cell nuclear transfer
121
What is somatic cell nuclear transfer?
Transferring a nucleus from a donor cell into an enucleated egg
122
What is a molecular clone in genetics?
A copy of a specific DNA sequence
123
Before PCR, how was DNA cloning primarily performed?
In vivo, within cells
124
What traditional method was used to genetically alter corn?
Selective breeding over thousands of years
125
What is the purpose of irradiating seeds in traditional genetic modification?
To induce random mutations
126
What does CRISPR allow scientists to do?
Precisely edit DNA sequences
127
Why is DNA referred to as a "universal language" in biology?
Genetic code is the same across all organisms
128
What do restriction enzymes do in genetic engineering?
Cut DNA at specific sequences
129
What are "sticky ends" in DNA cloning?
Overhanging DNA sequences that can pair with complementary ends
130
What is the function of plasmids in recombinant DNA technology?
Carry and replicate inserted genes in bacteria
131
What are the roles of promoters and terminators in a gene construct?
Promoters initiate and terminators stop transcription
132
How does heat shock enable bacterial transformation?
Temporarily increases membrane permeability to DNA
133
What is the purpose of antibiotic resistance genes in plasmid vectors?
To select for successfully transformed cells
134
What role did Cohen and Boyer play in biotech history?
Pioneered recombinant DNA technology using plasmids
135
What is electroporation in genetic transformation?
Using electric shock to allow DNA entry into cells
136
What does a gene gun do in plant genetic engineering?
Shoots DNA-coated particles into cells
137
Why are retroviruses useful in gene therapy?
They integrate genetic material into host DNA
138
What protein was the first successful recombinant product from Genentech?
Somatostatin
139
Why was somatostatin chosen over insulin for Genentech’s first project?
Smaller and simpler to synthesize
140
How was somatostatin released from the fusion protein in experiments?
By cleavage at methionine using cyanogen bromide
141
What bacterial system was used to control gene expression in Genentech's early experiments?
Lac operon
142
What molecule induces the lac operon to allow transcription?
IPTG (a lactose analog)
143
What is a fusion protein in genetic engineering?
A protein formed by linking two genes together
144
What is the significance of pSom2-3 in Genentech history?
Larger fusion protein that successfully expressed somatostatin
145
What are synthetic enzymes designed to do?
Catalyze specific reactions not performed by natural enzymes
146
What is the potential of enzyme design in synthetic biology?
Create new pathways and improve chemical synthesis
147
What ethical question does the film "Gattaca" explore?
The societal impact of human genetic engineering
148
What does newborn screening test for?
Treatable genetic and metabolic disorders
149
What is the difference between somatic and germline mutations?
Somatic affects body cells; germline is inherited
150
What is the purpose of pre-implantation genetic diagnosis (PGD)?
To screen IVF embryos for genetic conditions
151
What does chorionic villus sampling test?
Placental tissue for prenatal genetic disorders
152
What personal medical decision did Angelina Jolie make due to genetic risk?
Preventive double mastectomy for BRCA1 mutation
153
What is ex vivo gene therapy?
Modifying cells outside the body and reintroducing them into the patient
154
How does CAR T-cell therapy work?
Genetically modified T-cells target and kill cancer cells
155
Why are blood disorders good candidates for ex vivo gene therapy?
Blood cells are easily removed, modified, and returned
156
What does CRISPR-Cas9 do in gene editing?
Cuts DNA at targeted locations using guide RNA
157
What was Casgevy designed to treat?
Sickle cell disease and beta-thalassemia
158
How does Casgevy therapy reintroduce fetal hemoglobin?
Edits genes to reactivate fetal hemoglobin expression
159
Why is CRISPR more specific than restriction enzymes?
Uses a longer (20-nt) guide RNA for targeting
160
What is a potential risk of CRISPR gene editing?
Off-target effects causing unintended DNA changes
161
What is the main ethical concern of germline gene editing?
Changes are heritable and affect future generations
162
What was controversial about the CRISPR-edited babies in China?
They were modified to be resistant to HIV without medical necessity
163
What is mosaicism in the context of gene editing?
Presence of multiple genetically distinct cell populations in one individual
164
What does epigenetics demonstrate about gene expression?
Lifestyle/environment can affect gene activity without DNA changes
165
What are three-parent babies?
Babies with mitochondrial DNA from a donor to avoid inherited disease
166
How can mitochondrial DNA and Y chromosomes be used in ancestry?
Mitochondrial DNA traces maternal lineage; Y chromosome traces paternal
167
Why is personalized medicine based on genetic testing still challenging?
Many diseases are multigenic and influenced by environment
168
What does the "23" in 23andMe stand for?
The 23 pairs of human chromosomes
169
Why did 23andMe face public concern?
Potential misuse and privacy risks of genetic data
170
What is the central concept behind CRISPR’s precision?
Guide RNA targets a specific DNA sequence for editing
171
What triggers the adaptive immune response to begin during infection?
Pathogen level surpasses threshold antigen dose
172
How many days after infection do adaptive effector cells begin clearing pathogens?
4–5 days
173
What persists after infection that provides long-term protection?
Memory cells and antibodies
174
Which immune cells mediate humoral responses?
B cells
175
Which immune cells mediate cellular responses?
T cells
176
What kind of molecules do B cells produce to neutralize pathogens?
Antibodies (Immunoglobulins)
177
How do cytotoxic T cells recognize infected cells?
Via MHC I presenting foreign peptides
178
Which type of MHC do helper T cells recognize?
MHC class II
179
What do helper T cells do after recognizing MHC II-peptide complexes?
Activate B cells, macrophages, and cytotoxic T cells
180
What is the key principle behind immune recognition diversity?
Variation and selection
181
What immune cells present antigens to T cells in lymph nodes?
Dendritic cells
182
How do MHC I molecules present peptides?
Bind cytosolic pathogen fragments for CD8 T cells
183
Which pathogens are typically processed by MHC class II?
Extracellular or vesicular pathogens
184
What co-receptor aids CD8 T cells in binding to MHC I?
CD8
185
What co-receptor aids helper T cells in binding to MHC II?
CD4
186
What type of cell displays MHC II and activates helper T cells?
Antigen-presenting cells (APCs)
187
What structure in MHC I forms the peptide-binding groove?
α1 and α2 domains
188
What are the two protein components of MHC class I?
Heavy α chain and β2-microglobulin
189
Why can MHC class II bind longer peptides than MHC I?
Open groove at both ends
190
Where is polymorphism concentrated in MHC genes?
Peptide-binding cleft domains (α1/β1)
191
How is MHC expressed in individuals?
Co-dominantly, both parental alleles expressed
192
Why are siblings likely to differ in MHC profiles?
Different combinations of parental haplotypes
193
What part of the TCR binds to the MHC-peptide complex?
Hypervariable CDR loops
194
What generates diversity in T cell receptors?
V(D)J recombination
195
Where does T cell receptor gene rearrangement occur?
In the thymus
196
What is positive selection in T cell development?
Retention of TCRs that weakly bind self-MHC
197
What is negative selection in T cell development?
Elimination of TCRs that strongly bind self-antigen
198
What do B cells use to recognize antigens?
Membrane-bound immunoglobulins
199
What happens when a B cell internalizes an antigen?
Presents it on MHC II and gets activated by helper T cell
200
Into what type of cell does an activated B cell differentiate?
Plasma cell
201
What is the function of plasma cells?
Secrete antibodies
202
What determines the antigen specificity of an antibody?
Variable regions of light and heavy chains
203
What do we call an immune response involving many B cell clones?
Polyclonal
204
What is a monoclonal antibody?
Identical antibodies from a single B cell clone
205
What process increases antibody affinity over time?
Affinity maturation
206
What genetic process allows antibodies to evolve during an immune response?
Somatic hypermutation
207
How does somatic recombination contribute to immune diversity?
Randomly assembles V, D, and J segments
208
Why don’t all B cells in one person have identical genomes?
Somatic recombination and mutation
209
What ensures that each lymphocyte expresses only one receptor type?
Allelic exclusion
210
What is ELISA used for in labs?
Detect or quantify antibodies or antigens
211
What does an indirect ELISA detect?
Presence of antibodies
212
What does a sandwich ELISA detect?
Presence of antigens
213
Why do researchers use polyclonal antibodies?
They bind multiple epitopes on the same antigen
214
What is the immune function of CDR loops in antibodies?
Form antigen-binding sites
215
How are TCRs and antibodies structurally similar?
Both use Ig-fold domains with hypervariable loops
216
What is the function of restriction enzymes in cloning?
Cut DNA at specific sequences
217
What is the function of DNA ligase in cloning?
Join DNA fragments
218
What was the first human protein synthesized using recombinant DNA?
Somatostatin
219
Why was somatostatin chosen over insulin for Genentech’s first project?
Smaller and simpler to synthesize
220
What genetic feature allows bacteria to express foreign genes?
Plasmids with promoters and ribosome binding sites
221
How does CRISPR allow precise gene editing?
Uses guide RNA to target DNA for Cas9 cutting
222
What is gene amplification?
Increase in the number of gene copies
223
How is HER2 gene amplification detected in cancer profiling?
Using FISH and HER2/CEN17 ratio
224
What biological effect does HER2 amplification have?
Increased cell proliferation
225
What allows transcription factors to activate distant genes?
Binding to enhancers
226
What are epigenetic modifications?
Changes to gene expression without altering DNA sequence
227
What does acetylation of histones typically do to chromatin?
Opens chromatin, allowing transcription
228
What does methylation of DNA often result in?
Transcriptional repression
229
Why is gene expression described as a volume dial rather than a switch?
Genes can be regulated incrementally
230
What are the five levels of gene regulation?
Epigenetic, transcriptional, post-transcriptional, translational, post-translational
231
What is a bacterial operon?
Cluster of genes controlled by one promoter
232
What genes are found in the lac operon?
lacZ, lacY, lacA
233
What happens to the lac operon when glucose is low and lactose is present?
It is activated
234
Why do prokaryotes have coupled transcription and translation?
No nucleus separates processes
235
What separates transcription from translation in eukaryotes?
Presence of a nucleus
236
What is the role of steroid hormone receptors in gene expression?
Act as transcription factors
237
What are enhancers in gene regulation?
DNA regions that boost transcription when bound by proteins
238
What does the promoter of a gene do?
Initiates transcription
239
What genetic region signals the end of transcription?
Terminator
240
What modifications make pre-mRNA into mature mRNA?
5’ cap, poly-A tail, splicing
241
What is an example of a transcription factor "reading" DNA?
Binding specific sequences like Braille
242
Why is the major groove of DNA important?
Binding site for regulatory proteins
243
What does the central dogma describe?
DNA → RNA → Protein
244
What can influence gene expression besides DNA sequence?
Environment, epigenetics, chromatin structure
245
What is lactase persistence an example of?
Gene regulation allowing enzyme activity in adults
246
What does "DNA is not destiny" mean?
Gene expression depends on regulatory factors, not just sequence
