Exam #4 BIOTECH Flashcards
1
Q
What is forensic science?
A
The intersection of law and science used to investigate crimes and analyze evidence.
2
Q
What are some historic examples of forensic science methods?
A
1800s: Photography for documenting crime scenes.
Early 1900s: Fingerprinting for identifying individuals.
3
Q
What is molecular evidence in forensic science?
A
Analyzing DNA, which carries a unique set of alleles specific to each individual.
4
Q
How does DNA differ from person to person?
A
While the chemical structure of DNA is the same, the order of base pairs differs.
5
Q
Every cell contains a complete set of..
A
DNA that identifies the organism as a whole.
6
Q
How much of an individual’s DNA is unique compared to others?
A
Only one-tenth of 1% (0.1%) of DNA; equating to about 3.2 million nucleotide differences.
7
Q
When was DNA Fingerprinting/DNA Profiling introduced?
A
1985
8
Q
Who invented DNA fingerprinting
A
Sir Alec Jeffreys
9
Q
What technique did Sir Alec Jeffreys invent for DNA analysis?
A
Restriction Fragment Length Polymorphism (RFLP) technique.
10
Q
What are Variable Number of Tandem Repeats (VNTRs)?
A
Repetitive patterns of DNA present in all mammalian genomes; discovered by Alec while using RFLP.
11
Q
What is the unique signature found in each person’s genome?
A
A pattern of VNTRs and other DNA sequences that differ from individual to individual, forming their DNA fingerprint.
12
Q
How does RFLP work in DNA fingerprinting?
A
RFLP involves digesting DNA into fragments of different lengths using restriction enzymes, then analyzing the patterns of fragments to create a “fingerprint.”
13
Q
What type of genetic markers are most RFLP markers?
A
di-allelic and co-dominant, meaning both alleles in a heterozygote can be detected.
14
Q
Are RFLP markers specific to certain loci?
A
Yes, RFLP markers are highly locus-specific, meaning they target specific locations in the genome.
15
Q
RFLP inheritance
A
from mother and father.
16
Q
How is DNA used in rape investigations?
A
DNA from evidence, such as vaginal swabs, is compared to known samples from the victim and defendant to identify a match using techniques like RFLP or PCR.
17
Q
What does an autoradiograph show in DNA profiling?
A
It displays the patterns of DNA fragments from various samples, such as blood or swabs
18
Q
What samples are typically analyzed in a rape investigation using DNA profiling?
A
- Known blood sample of the victim.
- Known blood sample of the defendant.
- DNA size markers for reference.
- Female fraction from the victim’s vaginal swab.
- Male fraction from the victim’s vaginal swab.
19
Q
What are the two main types of forensic DNA testing?
A
RFLP (Restriction Fragment Length Polymorphism) and
PCR (Polymerase Chain Reaction) w VNTR
20
Q
What are the key features of RFLP in forensic DNA testing?
A
- Requires larger amounts of DNA.
- DNA cannot be degraded.
- No prior sequence information is needed.
21
Q
What are the key features of PCR in forensic DNA testing?
A
- Requires much less DNA.
- DNA can be partially degraded.
- Extremely sensitive to contaminating DNA.
- Requires prior sequence information.
22
Q
Why are DNA size markers important in DNA profiling?
A
They provide a reference to determine the sizes of DNA fragments in forensic samples.
23
Q
VNTRs are highly —, with a very large number of —.
A
polymorphic; alleles
24
Q
What are Microsatellites or Short Tandem Repeats (STRs)?
A
Repetitive DNA sequences:
2-6 base pairs long, repeated 5-50 times, and inherited from both mother and father.
25
What percentage of mammalian genomes is composed of STRs
3-5%
26
What is slippage during replication?
Slippage during replication is when DNA polymerase misaligns on the template strand, leading to errors in STR sequences.
27
How does slippage cause STR expansion?
When the newly synthesized strand loops out, leading to the addition of extra repeat units and STR expansion.
28
How does slippage cause STR contraction?
When the template strand loops out, resulting in the loss of repeat units and STR contraction.
29
How many STRs has the FBI chosen for DNA fingerprinting?
The FBI initially chose 13 unique STRs
30
What is CODIS?
CODIS stands for the Combined DNA Index System, the FBI’s database for storing and comparing DNA fingerprints.
31
When did CODIS become fully operational?
1998
32
What are the odds that 2 individuals will have the same 13 loci DNA profile
The odds are more than one in a billion, making the profile virtually unique
33
When did the FBI increase the number of required loci for DNA fingerprinting?
As of January 2007, the FBI required 20 loci for DNA fingerprinting.
34
Why did the FBI increase the number of loci analyzed in DNA fingerprinting?
Increasing the number of loci enhances the accuracy and discriminatory power of DNA profiling.
35
What is the role of PCR primers in STR analysis?
PCR primers anneal to unique sequences flanking the variable STR repeat region, allowing amplification of the repeat region for analysis.
36
What does "12 GATA repeats" represent in STR analysis?
It indicates that the individual has 12 repeats of the GATA sequence at a specific STR locus. Only the number of repeats is reported.
37
How are STR repeat numbers like "12 GATA repeats" determined?
The repeat number is determined by analyzing the length of the amplified DNA fragments using capillary electrophoresis or gel electrophoresis.
38
What are two methods to purify DNA for fingerprinting?
- Chemically: Using detergents to break down cell membranes.
- Mechanically: Applying pressure to force DNA out of cells.
39
What precautions should be taken during DNA collection to avoid contamination?
- Wear disposable gloves and change them frequently.
- Use disposable sample-collecting instruments.
- Avoid talking, sneezing, coughing, or touching your face, nose, or mouth.
- Air-dry evidence before packaging to prevent mold growth.
40
What are the main enemies of DNA evidence?
1. Sunlight and high temperatures: Can degrade DNA.
2. Bacteria: Can contaminate or break down DNA.
3. Moisture: Encourages mold growth, which can damage samples.
41
What is the best sample from a suspect's DNA
fresh, whole blood; Leukocytes (white blood cells).
42
How old can a DNA sample be and still be analyzed successfully?
DNA can be retrieved and analyzed from samples that are over a decade old using PCR.
43
What role does PCR play in analyzing degraded DNA samples?
Amplifies DNA found at crime scenes into an amount that can be analyzed.
44
How are specific STR sites amplified during PCR?
DNA primers are designed for the flanking regions of CODIS sites, enabling targeted amplification of specific STR regions.
45
What special feature must one of the PCR primers have in DNA fingerprinting?
One of the 2 primers must be fluorescently labeled.
46
What information can be determined from STR analysis?
The number of repeats in each allele on homologous chromosomes at specific STR loci.
47
What is the basis of DNA testing in forensic science?
DNA testing is based on exclusion, continuing only until a difference is found.
48
What happens if no differences are found during DNA testing?
If no differences are found after statistically sufficient testing, the probability of a match is considered high.
49
Is eyewitness testimony more reliable than DNA testing in forensic cases?
No, DNA testing is considered more reliable as eyewitness accounts can be influenced by biases and errors.
50
What happened in the Forest Hills Rapist case in Queens, NY (1987)?
Victor Lopez was tried for the sexual assault of three women, despite eyewitnesses describing the assailant as a black man. Lopez, who was not black, was linked to the crimes through DNA evidence.
51
How was DNA used after the World Trade Center attack on September 11, 2001?
DNA techniques were used to identify the remains of victims amidst tremendous debris, heat, and microbial decomposition.
52
What challenges did forensic scientists face when using DNA to identify victims of the World Trade Center attack?
Challenges included processing hundreds of thousands of tissue samples from nearly 30,000 individuals, dealing with heat damage, microbial decomposition, and massive debris.
53
What types of samples were used for DNA isolation after the World Trade Center attack?
cheek swabs from relatives and personal items from the missing.
54
What DNA analysis techniques were used to identify victims of the World Trade Center attack?
Short Tandem Repeat (STR) analysis, mitochondrial DNA (mtDNA) analysis, and Single Nucleotide Polymorphism (SNP) analysis.
55
What major natural disaster occurred in December 2004, and what was the death toll?
The South Asian Tsunami occurred in December 2004, resulting in the loss of over 225,000 lives.
56
How many tsunami victims were identified within three months of the disaster?
800.
57
What DNA techniques were used to identify victims of the South Asian Tsunami?
mtDNA and Y-STR's
58
Why were mtDNA and Y-STR analysis used in identifying tsunami victims?
These methods are effective in analyzing degraded samples; mtDNA is maternally inherited, and Y-STR analysis can trace paternal lineages.
59
How many DNA samples were collected in the Simpson/Goldman murder case
45 samples
60
What was announced in the pre trial hearings (1995)
DNA collected matched O.J's
61
Why was DNA evidence not effective in the Simpson/Goldman murder case?
The DNA evidence was challenged due to concerns about potential contamination and mishandling of the evidence during collection and testing.
62
Why is the chain of custody important in DNA analysis?
The chain of custody ensures that evidence is systematically recorded and access is controlled, preventing compromise or contamination of samples.
63
What challenges arise when presenting DNA evidence to juries?
DNA evidence must be clearly explained, as statistics like "1 chance in 50 billion" can confuse juries and lead to disproportionate focus on the improbable outcome.
64
What is the purpose of paternity testing using DNA profiles?
To analyze DNA samples from a child and adults involved to determine if a specific man is the father of the child.
65
How can paternity be tested before a child is born?
Fetal cells can be drawn from the amniotic fluid and tested for paternity.
66
Why is mitochondrial DNA (mtDNA) used in some DNA analyses?
Examines older samples like hair, bones, and teeth that lack nucleated cellular material and cannot be analyzed by RFLP or STR.
67
How is mitochondrial DNA inherited?
mtDNA is inherited almost exclusively from the mother.
68
What is a notable feature of mitochondrial DNA compared to the nuclear genome?
mtDNA has a 100-fold higher mutation rate than the nuclear genome.
69
What is the Ginseng (herbal products) market worth in the US
$3 million
70
What are the two types of ginseng commonly referred to in the U.S. market?
The two types are Asian ginseng, which boosts energy, and American ginseng, which calms nerves.
71
Why is American ginseng more valuable than Asian ginseng?
American ginseng is rarer, making it more valuable despite its calming effects compared to Asian ginseng's energy-boosting properties.
72
How was DNA evidence used to prove a hunter killed a bear illegally in Pennsylvania?
Blood samples collected from a den were compared to DNA from the bear's premolars, confirming a match.
73
Why are models of human disease important in research?
Because human genetics cannot be manipulated for experimental purposes, allowing scientists to study diseases using other organisms.
74
What percent of human genes are similar in structure and function to other species?
Mice: 92%
Zebrafish: 70%
Fruit fly: 44%
Nematode: 35%
75
What are homologs?
Important genes that are highly conserved across species based on their DNA sequence, enabling comparative genetic studies.
76
Why is studying apoptosis in C. elegans important?
It helps scientists understand the process of apoptosis in human neurodegenerative diseases.
77
What makes fruit flies valuable for studying human genetics?
Many genes determining body plans, organ development, aging, and death in humans are identical to those in fruit flies.
78
What percentage of genes mutated in 289 human diseases are also found in fruit flies?
61%
79
What can researchers achieve by using model organisms for human disease research?
- Identify disease genes.
- Test gene therapies.
- Develop drug-based therapeutic approaches.
- Determine gene therapy effectiveness.
- Check safety in preclinical studies.
80
What does the Ob gene code for in mice and humans?
The protein leptin; which travels to the brains and regulates hunger.
81
Which cells produce leptin?
Adipocytes (fat cells).
82
What happens if the Ob gene is nonfunctional?
Leptin is not produced, and mice/humans become obese.
83
How did the Human Genome Project (HGP) impact genetic disease testing?
Before the HGP, only 100 genetic diseases could be tested for; after the HGP, over 2000 genetic diseases could be tested.
84
What is a biomarker?
A measurable indicator of a biological state or condition, often proteins produced by diseased tissue or upregulated in disease.
85
Give an example of a biomarker and its associated disease.
PSA (prostate-specific antigen) is a biomarker for prostate cancer.
86
What are two common methods for detecting chromosome abnormalities in a fetus?
Chorionic villus sampling (CVS) and amniocentesis.
87
At what stage of pregnancy is chorionic villus sampling (CVS) performed?
At 8-10 weeks of pregnancy.
88
What is removed during chorionic villus sampling (CVS), and why?
A small portion of the chorionic villus, a layer of cells that helps form the placenta, to create a karyotype.
89
At what stage of pregnancy is amniocentesis performed?
At 14-16 weeks of pregnancy.
90
What sample is taken during amniocentesis, and what is it used for?
A sample of amniotic fluid, used to create a karyotype for detecting chromosome abnormalities.
91
What is fluorescence in situ hybridization (FISH)?
An updated technique for karyotyping that uses fluorescent probes to identify and analyze chromosomes.
92
What types of chromosome abnormalities can fluorescence in situ hybridization (FISH) detect?
Missing chromosomes, extra chromosomes, and defective chromosomes.
93
What does RFLP detect?
It detects variations in DNA fragment lengths, which can indicate the presence of mutations in specific genes.
94
What is allele-specific oligonucleotide analysis (ASO)?
A method used to detect specific mutations at the level of a single nucleotide, even if the mutation does not affect a restriction enzyme recognition site.
95
How does allele-specific oligonucleotide analysis (ASO) work?
ASO uses short DNA probes that bind specifically to a mutated allele, allowing for the detection of single nucleotide changes in a gene.
96
What is preimplantation genetic testing?
A process using ASO, PCR, and FISH to screen for gene defects in single cells from 8- to 32-cell-stage embryos created by in vitro fertilization (IVF).
97
What are SNPs (single nucleotide polymorphisms)?
The most common form of genetic variation among humans, making up 90% of human genetic variation.
98
How can SNPs in a gene sequence affect protein structure?
An SNP can cause a change in protein structure that produces disease or influences traits in various ways.
99
What diseases can SNPs be used to predict susceptibility to?
Stroke, diabetes, cancer, heart disease, and behavioral and emotional illnesses.
100
What are DNA microarrays?
DNA microarrays are glass microscope slides spotted with DNA "probes" representing genes.
101
What are DNA microarrays used for?
To screen a patient for patterns of alleles that might be expressed in specific disease conditions.
102
What do RNA microarrays analyze?
RNA microarrays analyze a patient’s transcriptome, which includes all mRNA in a population of cells.
103
How do DNA and RNA microarrays differ?
DNA microarrays use DNA probes to screen for allele patterns, while RNA microarrays analyze the transcriptome to identify gene expression levels in disease conditions
104
What is the function of oncogenes?
Genes that are involved in the growth of cancer cells.
105
What do tumor suppressor genes do?
They produce proteins that keep cancer formation in check.
106
What is pharmacogenomics?
Pharmacogenomics is the study of how a person's genetic profile affects their response to drugs.
107
What was one of the first successful examples of pharmacogenomics?
The drug Gleevec, introduced by Novartis in 2001.
108
What does Gleevec target in treating Chronic Myelogenous Leukemia (CML)?
Gleevec targets the BCR-ABL fusion protein
109
What is the BCR-ABL fusion protein a result of?
Results from the exchange of DNA between chromosomes 9 and 22 and causes CML.
110
Why do individuals react differently to the same drugs?
Differences in drug response and side effects occur due to genetic polymorphisms.
111
Why does chemotherapy have side effects?
It targets rapidly dividing cells, affecting both cancer cells and normal cells like hair, skin, and bone marrow cells.
112
What is the goal of 'magic bullet' drugs in cancer treatment?
To destroy only cancer cells without harming normal cells.
113
What are the genes involved in breast cancer?
BRCA1 and BRCA2.
114
How can RNA or DNA from breast tumor tissue be used in personalized medicine?
It can be analyzed using SNP and microarray techniques to identify the genes involved in a specific form of breast cancer, allowing for tailored drug treatment strategies.
115
What is the purpose of cancer vaccines?
Inject cancer cell antigens to stimulate the immune system to attack cancer cells:
a therapeutic, not preventative, treatment.
116
What are monoclonal antibodies (Mabs)?
Purified antibodies that are highly specific for certain molecules.
117
What can Mabs treat?
- Lymphoma
- Breast cancer
- Alzheimer’s
- Drug addiction.
- Heart Disease
- Transplant rejection
118
What are the steps to produce monoclonal antibodies?
1. A mouse or rat is inoculated with the desired antigen to elicit an immune response.
2. The spleen is harvested to obtain antibody-producing cells.
3. Spleen cells are fused with myeloma cells (tumor cells) that no longer produce their own antibodies.
119
What is Myeloma?
An antibody-secreting tumor; they accumulate and contribute to multiple health issues.
120
What is the result of fusing B cells with a myeloma cell in the production of Mabs?
A hybridoma grows continuously and rapidly, producing the antibody specified by the spleen cells.
121
What is gene therapy?
The delivery of therapeutic genes into the body to correct conditions created by faulty genes.
122
What are the two primary strategies for gene therapy?
Ex vivo and In vivo gene therapy.
123
What is ex vivo gene therapy?
Removing cells from the patient, treating them with techniques similar to transformation, and then reintroducing the cells back into the patient's body.
124
What is in vivo gene therapy?
In vivo gene therapy involves directly introducing genes into tissues and organs in the body
125
What is the challenge with in vivo gene therapy?
Delivering genes only to the intended tissues and not to other tissues throughout the body.
126
How do viral vectors work in gene therapy?
Viral vectors use genetically engineered viral genomes to carry therapeutic genes, infecting human cells to introduce the genes into the body.
127
What is an example of a virus used as a vector for gene therapy?
adenovirus (common cold), influenza virus (flu), and herpes virus (cold sores, some cause STDs).
128
What vaccines used adenovirus vectors?
Johnson & Johnson and AstraZeneca vaccines
129
What is the primary concern when using viruses as vectors for gene therapy?
Ensuring the virus has been genetically engineered so that it cannot produce disease or spread throughout the body.
130
How do viruses infect human cells?
They bind to and enter human cells, release their genetic material into the nucleus or cytoplasm, where the host cell reproduces the viral genome.
131
Why are viruses good vectors for gene therapy?
- Efficient at infecting many types of cells
- Some viruses, like retroviruses (HIV), permanently insert their DNA into the host cell genome.
- Some viruses can also infect specific cells.
132
What is "naked DNA" in gene therapy?
Naked DNA refers to DNA that is injected directly into body tissues without any viral or nanoparticle carrier. Only a small number of cells take up the injected DNA.
133
What are liposomes used for in gene therapy?
Liposomes are small, hollow nanoparticles made of lipid molecules that can carry genes and can be injected or sprayed into tissues to deliver DNA.
134
Examples of Liposome delivery
Pfizer/BioNTech and Moderna
135
What was the first human gene therapy?
The first human gene therapy was performed in 1990 on a patient with Severe Combined Immunodeficiency (SCID).
136
What is Severe Combined Immunodeficiency (SCID)?
genetic disorder caused by a defect in the gene called adenosine deaminase (ADA).
137
What is the role of the ADA enzyme?
The ADA enzyme is involved in the metabolism of nucleotide dATP, helping to regulate the immune system.
138
How does the ADA defect affect the immune system in SCID patients?
The accumulation of dATP in SCID patients leads to the destruction of T cells. Without helper T cells, B cells cannot recognize antigens/produce antibodies.
139
What is regenerative medicine?
Regenerative medicine involves growing cells and tissues that can be used to replace or repair defective tissues and organs.
140
What are stem cells?
Stem cells are undifferentiated cells that have the ability to divide and differentiate into specialized cell types.
141
What are the two layers of the blastocyst?
Trophoblast (outer layer, forms the placenta) and the inner cell mass (source of human embryonic stem cells).
142
What can human embryonic stem cells (hESCs) differentiate into?
They can differentiate into all of the more than 200 cell types in the human body, making them pluripotent.
143
Source of hESCs
hESCs are derived from embryos left over from in vitro fertilization (IVF) or embryos specifically created for research purposes from donated sperm and egg cells.
144
What is the ability of human embryonic stem cells (hESCs) to self-renew?
can self-renew indefinitely, producing more stem cells.
145
What are cell lines in stem cell culture?
Cell lines are cultured cells that can be maintained and grown successively, allowing for ongoing research and experimentation.
146
What can hESCs be stimulated to do?
To differentiate (directed differentiation) into specific types of differentiated cells. "key interest" to create tissues for regenerative medicine.
147
What is a major focus of stem cell research?
determining what factors bring about pluripotency and identifying the factors that stimulate differentiation into specific cell types.
148
What are totipotent stem cells?
cells capable of giving rise to any cell type or even a complete embryo.
149
What are pluripotent stem cells?
cells capable of developing into any cell type or tissue except those that form the placenta or embryo.
150
What are multipotent stem cells?
can give rise to many, but limited, types of cells. They are found in adult tissues and have the ability to self-renew.
151
Why is research on hESCs controversial?
They come from early human embryos.
152
Potential sources of hESCs
- adult stem cells (ASCs)
- amniotic fluid-derived stem cells (AFSs)
- cancer stem cells (CSCs)
153
Adult Stem Cells
- Reside in mature adult tissue and can be cultured and differentiated
- small in number, not discovered in all adult tissues yet
- can be direct differentiated but not as pluripotent as hESCSs.
154
Amniotic fluid-derived stem cells
- isolated from human amniotic fluid
- can be coaxed to become neurons, muscles cells, adipocytes, bone, blood vessels, and liver cells.
155
Cancer stem cells (CSCs)
- involved in development of cancers, tumor progress, metastasis.
- can self-renew and differentiate to form into tissues they were derived from
- focuses on intense research and potential for cancer treatment.
156
What is another method of deriving stem cells?
Creating them by nuclear reprogramming of adult skin cells. INDUCED PLURIPOTENT STEM CELLS (iPSCs)
157
What was the first success of iPSCs
2005 with mice and then humans in 2007
158
Who is behind iPSCs
Dr. Shinya Yamanaka; Kyoto University
