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143 Cards in this Set
- Front
- Back
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SCID,Cystic Fibrosis, Hemophilia A and B,Gaucher Disease, Sickle Cell Disease, Thalassemia, Cancer therapy, Diabetes...what do they all have in common?
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Diseases Targeted for Gene Therapy Cures
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Describe in 4 steps the process of using engineered viruses to introduce alleles into human cells.
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1. virus has recombinant RNA which has both viral and human sequences.
2. Recombinant genes enter cell 3.Viral enzymes make double-stranded DNA version of introduced cells. 4.Recombinant genes are inserted into the host chromosome and transcribed. |
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Virus hereditary material can be...
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RNA/DNA and single/double-stranded.
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Does virus have plasma membrane present?
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no
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Why can't viruses carry out trascription independently
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Even if polymerase is present, it required ATP and nucleotides provided by the host's cell.
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Nonenveloped viruses have to recognize the cells they want to infect so they have...
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receptors on their protein coat
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__ viruses have very geometrical shapes
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Adenoviruses/nonenveloped
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____: Cause respiratory, intestinal, and eye infections in humans
Double-stranded DNA genome |
adenovirus
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____: The inserted DNA is not incorporated into the host genome. For gene therapy, express for a relatively short time and have to be reinserted when more cells divide
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adenovirus
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____: Used for treating individuals that suffer from disorders of the lung such as cystic fibrosis
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adenovirus
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Enveloped virus has ___ which is a ___ which typically comes from the host's membrane.
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enveloped, phospholipid bilayer.
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___ don't have geometric shape because of envelope
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enveloped viruses
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Example of enveloped virus...which is also an example of a what?
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HIV, retrovirus
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____: goes through reverse transcription using reverse transcriptase and RNA.The double stranded viral genome integrates into the human genome using integrase
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retrovirus
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___: integrase inserts the gene anywhere because it has no specific site.
May cause ____ where one gene disrupts another gene’s code (disrupted cell division causes cancer from uncontrolled cell division) |
-retrovirus
-insertional mutagenesis |
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The virus life-cycle involves ___(...) growth and sometimes _____ growth
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lytic (results in a new generation of viruses particles and death of cell), lysogenic
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5 steps of lytic replication in a virus
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1.viral genome enters host cell
2. it is replicated and trascribed 3.viral mRNAs are translated and proteins processed 4.particles assemble inside host 5.exit cell |
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Only some viruses are capable of lysogenic replication (...).
The ___ retrovirus is one example |
virus genes being trasnmitted to daughter cells of host.
HIV |
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Describe in 4 steps lysogenic replication:
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1.viral genome enter cell
2. it integrates into host cell genome 3.host-cell DNA polymerase copies chromosome 4.cell divides and virus genes trasnmitted to daughter cells. |
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Most retroviral vectors are based on ___ which is capable of infecting both ____ and human cells.
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-Moloney murine leukemia virus (Mo-MLV)
-mouse |
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retroviral vectors: The viral genes, __, ___ and ___ (...), are replaced with the transgene of interest and expressed on plasmids in the packaging cell line
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gag, pol, env
which are protein of viral replication and integration |
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Any genes that lack the “____” will not be replicated and thus will not included in the virion particle.
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packaging sequence
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Retrovirus genome:
pol: LTR: env: gag: These constitute the "packaging sequence." |
LTR: long terminal repeat (needed for integration into host genome)
pol:polymerase. Contains enzymatic activities not present in host env:envelope. Coat protein on surface of virus that interacts with cells the virus will infect gag:group specific antigen. Codes for core structural proteins of virus. |
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In the packaging cell (where we engineer the virus) the virus DNA segments can’t replicate themselves because they don’t have the ___.
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packaging sequence
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How do the envelope proteins assemble automotically?
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non-polar component
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SCID(....): Lack of function of B and T lymphocytes(...)
Which has two causes: |
-(Severe combined immunodeficiency)
-(the key cells in the immune system) -mutation in ADA gene= deficiency in adenosine deaminase(enzyme) and mutation in "gamma-c" receptor on X chromosome(SCID-X1) |
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In SCID, absence of adenosine deaminase...
In SCID-X1 (deficiency of "gamma c"... Therapy for 1st one uses somatic cells whereas 2nd one uses stem cells from bone marrow. |
metabolic intermediate builds up in cells that is particularly toxic to B and T cells
-deficiency in protein necessary for growth and differentiation of T cells so T cells never mature. |
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T-cell leukemia associated with trasngene insertion into ____
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1st intron of the LMO2 gene
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Knockout genes = prevent from being carried out. Not dealing with gene itself directly but ___
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mRNA
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sI (small interfering): targets ___ made from that gene. What then, needs to be donw with the trasngene
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-mRNA
-eliminate the sequence that sI recognizes. |
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In the gene therapy for mice with sickle cell...what was one problem they had to overcome?
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expression level
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DNA polymerase works under what specific arrangement of DNA?
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Single-strand as a template plus 3- end to start DNA synthesis
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Replication fork:
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Y-shaped region where the parent DNA double helix is split into two single strands, which are then copied.
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What are the fragments called on the lagging strand?
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Okazaki fragments
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Reiji Okazaki and Tsuneko Okazaki, working in collaboration, discovered the ____ nature of DNA replication in 1968.
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-discontinuous
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DNAn + dNTP --->
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DNAn+1 + PPi
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Helicase
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enzyme that open up DNA
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What does DNA polymerase I do?
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removes and replaces the primers on the lagging strand
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What does ligase do?
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after DNA polymerase I replaces primer, ligase comes in and fills the gap (binds the two fragments).
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What is the main difference between replication of circular chromosome and linear chromosome (besides points of origin)
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incomplete ends
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Telomeres do not contain ____. They consist of short stretches of bases of ____ repeated sequence: (____ on the complimentary strand).
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-genes
-TTAGGG -CCCTAA |
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Something other than DNA polymerase is thus required to replicate the DNA under the special conditions that exist at the ends (telomeres) of replicating chromosomes.
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telomerase
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telomerase is a ribonucleoprotein (...)
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a molecule composed of both RNA and protein
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Telomerase contains one RNA molecule called ___
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TERC (telomere RNA component)
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In telomerase, different organisms contain different TERC sequences, and ____
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hence have different telomere sequences
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The protein component of telomerase, which also is the catalytic component, is called
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TERT
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Telomerase is a what type of enzyme?
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reverse transcriptase
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In humans, the telomeres are about ____ nucleotides long, repeating units of AATCCC
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10,000
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Tetrahymena have what telomere
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GGGTTG
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Biologists convinced that ____ involved in the normal aging process.
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telomere shortening
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Telomerase IS found, however, in: (4)
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cancer cells, embryonic stem cells, adult stem cells, unicellular eukaryotes
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Metastasis:
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spreading and establishing of secondary tumors elsewhere in the body
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Recent data reveal
an increase in survival rate from breast cancer, due in part to two developments: |
1. Better methods of early detection
2. New and better combinations of drugs for treatment (e. g.tamoxifen and taxol) |
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In general, six properties
are altered in cancer cells. |
self-suffciency in growth signals, insensitivity to anti-growth signals, evasion of apoptosis, limitless replicative material, tissue invasion and metastasis, sustained angiogenesis.
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Angiogenesis
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growth of blood vessel. If the tumor can’t undergo it then it can’t grow.
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comes in D form and ? Form. Not superimposable. One causes birth defects. Couldn’t undergo angiogenesis to take blood vessels to the limbs thus they had short limbs. So scientists working with this in cancer research.
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Thalidomine
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APC
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protein from APC gene...tumor supressor
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These genes occur and function normally, but when mutated, become oncogenes, which then contribute to uncontrolled cell growth.
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Proto-oncogenes
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responsible for normal progression of cells through the cell cycle, for example, during growth and/or early development. When mutated to become an oncogene, they no longer respond to normal control mechanisms and instead promote cell cycle progression continuously
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Proto-oncogenes
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This class of genes normally block the action of transcription factors that induce the expression of genes that promote cell cycle progression. Thus, they act like ‘brakes’ on the cell cycle, hence their name. When mutated or lost, they no longer function and thus cell cycle progression is allowed when it should not occur
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Tumor suppressor genes
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different patients
have differing expression levels of the groups of genes being analyzed. As a result.. |
cancers are so difficult
to treat, let alone cure. |
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classification of Good signature =
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tumor is less aggressive.
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Lympth node negative patients means =
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tumor hasn't left lympth nodes
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What are Benzo(a)pyrene (component of ____) and
Aflatoxin (found in __). |
carcinogens
-cigarette smoke -peanut butter |
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The tumor suppressor protein ___ is particularly sensitive to various mutagens, in a
surprisingly confined region of the primary sequence: |
-p53
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5 ways to cause mutation in p53 protein
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smoking(Benzo(a)pyrene), deamination (take off amine group), food contamination(Aflatoxin),engenous process (liver metabolism), UV light.
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What might be the consequences of expressing telomerase in somatic cells? But recall, the development of cancer...
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1.cancer
...is a multi-step process that involves several changes. |
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a genetic disease characterized by premature aging, in which afflicted individuals die of ‘old age’ at around 12 years of age. It is extremely rare.In which the defective genes codes ___, which ___. What else has been linked to shorter telomered?
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Progeria
Lamin A, helps form nuclear envelope stress |
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Besides reducing stress, another way to increase longevity...
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eat less (caloric restriction)
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is that of a population, and is a function of living conditions, diet, air and water quality, disease, etc.
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average life span
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caloric restriction has led to the discovery of a gene called ___ (in mammals it is called ___). The gene encodes a protein called ____.
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Sir2, SIRT1, sirtuin (enzyme)which has the same structure as a carcinogen
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___ is a plant product sold as a health supplement where in experiments with mice, increases the level of sirtuin (i. e. it enhances the expression of SIRT1)!
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Resveratrol
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Approaches to longevity (4)
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1.RNAi
2.Stem cells 3.Gene chip analysis (to find what genes are expressed in aging and prevent them from being expressed). 4.Suicide genes (ex: have tumor and target it with vector that carries the suicide gene and hopefully induce apoptosis). |
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Jan Swammerdam (1637-80)
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-Demonstrates that nerve stimulation causes contraction of frog muscle.
-Showed that the ability to control muscle contraction not require a brain. |
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Luigi Galvani (1737-1798)
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1786. Muscular contractions caused by the flow of electricity from nerve to muscle. Considered “animal electricity” as a fluid, produced in and secreted by the brain, which flowed along the nerves to activate the muscles.
-Experiments that inspired Shelley. |
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Dentrites do....
cell body does... axon does.... |
-collect electrical signals
-integrates incoming signals and generates ongoing signal to axon -passes electrical signals to dentrites of another cell. |
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two important reasons for the creation of a membrane
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higher efficiency and protect inner workings
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Fatty acid composed of what two groups...what are the other kinds
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carboxyl and hydrocarbon chain
-isoprene |
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bonds for saturated and unsaturated?
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yes and no
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___ have much more chemical energy that unsaturated fats because they contain more C-H bonds.
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saturated fats
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fats consist of ___ linked to three ___. This is called a___
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glycerol, fatty acids, triacylglycerols
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fatty acid and glycerol joined by ___ linkage
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ester
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saturated fats solid at room temp because...
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of extensive hydrocarbon on interaction
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Membranes are ____ permeable.
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selectively
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spherical phispholipid, not planar one, is ____
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energetically favored
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Artificial membrane-bound vesicles
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liposomes
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___ can be used to deliver experimentally interesting goodies to the inside
of cells. |
Liposomes
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Three classes of membrane proteins
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peripheral, integral, lipid anchored
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to reveal the inside of the bilayer
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Freeze fracture
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large uncharged polar, hydrophobic, ions, small uncharged polar --> rank in order of most permeable
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hydrophobic, small polar, large polar, ions
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Two aspects of a hydrocarbon could affect the way the chain behaves in lipid bilayer
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# of double bonds and length
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When ions build up on one side of a membrane, they establish a combined...
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concentration and electrical gradient (electro-chemical)
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4 kinds of membrane transport
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simple diffusion, facilitated difusion via channel protein, facilitated diffusion via transporter, and active transport.
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___: hydrophilic pores, diffusion limited, ion selective, sometimes gated by ligands/voltage, permits 10^6 ions/sec
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ion channels
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____: undergo conformational change during trasnport, selective, saturable and more than 1000 times slower than channels
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carriers/transporters
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why would you want to have gated channels
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don't always want them in equilibrium
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cystic fibrosis caused by mutation in ____ gene which codes for ____ channel. Consequences:
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CFTR, Cl-, lung congestion and infections
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The ____ is used to monitor ion channel activity. Where you use a flui-filled ____. With it you can determine if channel is ___/___
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patch-clamp technique, microelectrode, open or closed.
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“___” refers to the conditions required to open a channel
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Gating
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4 kinds of gated channels
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voltage-gated, ligand-gated (intra and extra), mechanically-gated
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at resting potential, voltage-gated Na+ channels are ___
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closed
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three condition you can have with gated-channel
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closed/rest, open, deactivated (with inactivation peptides with tethers-longer = keeps open longer)
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primary active transports/pumps use ____ to _____ against ____. For each ATP how many Nat+ out and how many K+ in? What is the purpose
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atp, drive transprt, concentration gradient
-3 to 2 -to create electro-voltage gradient |
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How Na+/K+ ATP-ase works (4)
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1.3 Na+ enters the enzyme from within the cell
2. ATP phophorylated the enzyme, causing it to pump the ions out 3. two K+ enter enzyme 4. the now unphosphorylated enzyme pumps them in |
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Thickened mucus in lungs leads to (1) obstruction of airways and (2) growth of bacteria...symptoms of
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cystic fibrosis
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We have ___ion outside and ___ ion inside and resting potential of ___ volts.
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Na+,Cl-,-70
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A difference of electrical charge between any two points creates a difference in electrical potential, or ____
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voltage
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At resting potential, a lot of __ inside and a lot of __ and ___ outside.
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K+, Cl-, Na+
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At rest, the only channel that is open is one that allows __ to flow, sometimes called __
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K+, leak channels...so cell has to actively pump Na+ out and pump K+ back in.
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charge inside cell during resting potential
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negative
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When K+ goes outside during repolarization, going against ____gradient and with ___ gradient
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concentration, voltage
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When does depolarization occur and what happens...reaches what voltage
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when it goes from -70 to -50...and then Na+ channels open causing further depolarization...+40
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when does repolarization of the membrane occur...and then what happens
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when the active potential reaches +40 voltage...then K+ channel open and the potential reaches negative again.
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Where as depolarization mostly involed ____of ions, repolarization is ___ of ions
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influx , outflux
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propagation of action potential (3)
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1.Na+ enters axon
2.charge spreads; membrane downstream depolarizes 3.voltage-gated channels open in response to depolarization |
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refractory period
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after active potential, pulse has gone through. Na+ channels deactivated, hyperpolarization from undershoots also contributes to this
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Schwann cells known collectively as ___ which make up the ____
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glia, myelin sheath
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During propagation of active potential...it jumps at the nodes of the myelin sheath called
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Node of Ranvier
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_____ results from degeneration of myelin sheath
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Multiple sclerosis
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what happens when action potential reaches terminal, which causes __
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influx of Ca2+, vesicles containing neuros to bind to presynaptic membrane and release the neuros and ion channels on postsynaptic neuron open open and so causes change in postsynaptic potential
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neuros are, which bind to
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ligands, ligand-gated channels
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EPSPs (...) causes what
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Excitatory postsynaptic potential = depolarization, influx of Na+, makes action potential more likely to happen
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IPSPs(...) causes what
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Inhibitory posynaptic potential = hyperpolarization, influx of K+ and Cl- which makes action potential less likely to happen
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EPSPs and IPSPs are not ___, they can be additive. They, for one thing, depend on ___
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all-or-nothing
amoutn of neuros |
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sodium channels that trigger action potential located here.
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Axon hillock
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Barbituates and tranquilizers (Valium, Halcion) bind to GABA-gated Cl- channels. They make the channel easier to open by GABA. How would this affect the nerve impulse
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Makes it harder to stimulate impulse due to Cl- flowing into the cell.
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Antidepressant Prozac ___ ____ of excitatory neurotransmitter serotonin
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blocks reuptake
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Defects in ligand-gated channels can result in ____
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mental illness
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___ results in symptoms that can mimic schozophrenia, so used as drug to study neurological changes related to schizophrenia. It changes the number anf function of ___
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PCP (angel dust)
NMDA-sensitive glutamate receptors (glutamate is an excitatory neurotransmiter) |
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Hypothesis to explainlink between NMDAreceptors and schizo
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receptor made up of two subunits and schizos have too little unit1 and too much unit 2 so has few good receptors and lots of faulty ones....so there's a decreased ease in making an action potential
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Recovery from paralysis in adult rats using embryonic stem cells
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treat ES cells with retinoic acid and the developmental morphogen Sonic Hedgehog which induces formation of motor neurons, tranplant into spinal chord, in three months the axons reach the skeletal muscles.
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Due to inactivation or destruction of neurons at base of brain (substantia nigra) =____. These secrete ___ regulate motor neurons along spinal cord.
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Parkinson's disease
dopamine |
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Brain is made up of 4 distinct structures
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pons(relays sensory information to cerebellum), medulla(automatic center for regulating hearts, lungs, and digestive system, cerebrum(conscious thought and memory), cerebellum(coordinates complex motor
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cerebrum has four lobes
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temporal, frontal, parietal, occipital
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left frontal lobe involed in; temporal lobe involved in
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speech, memory
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what kind of neurons Found in humans, great apes dolphins, whales that have intricate connection and seem to be about emotions.
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spindle...large and deeeply connected axons? dentrites? Implicated in intelligence behavior
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what organisms investigated for "learning"
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sea slug aplysia californica (gill withdrawal)
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Chemical changes occur after ‘learning’
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Neurons involved in learning release neurotransmitter serotonin, which causes causes an excitatory postsynaptic potential (EPSP) in motor neuron to the gill.
Result is that the serotonin-secreting cell now releases much higher levels of serotonin after going through ‘learning’ process So now stronger EPSP occurs. Stimulated neurons also established additional synapses |
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Synaptic plasticity
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changes in the synapse form the molecular basis for learning and memory
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Structural/chemical changes (associated with memory/learning) might include modifications in the (3)
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# of synapses, alterations in the amount of neuros released, change in the amount of receptors
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postsynaptic potentials change as a result of
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learning
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ICMS=intracortical microstimulation...what would be the benefit of this technology?
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Attempt to make new neural pathways/connections. Rewriting the brain (help people with strokes who have loss use of normal “circuitry”.
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Learning to Control a Brain–Machine Interface for Reaching and Grasping by Primates...benefit?
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help the disabled
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