GN301 Final

RNA Interference (RNAi)

discovered by Fire and Mello; genes with same sequence as injected RNA decrease in expression

siRNA

small, interfering RNA; targets the gene it comes from (pairing precise)

miRNA

micro RNA, targets a gene other than what it comes from (not precise)

dicer

enzyme that cuts double-stranded RNA into specific length

argonaut

binds to siRNA or miRNA to form RISC

RISC

RNA induced silencing complex; binds to target mRNA sequence and prevent translation or causes degradation of the mRNA

use of RNAi

\-study gene function

\-agriculture to target pests

\-medicine in gene therapy

off target effects

gene with an accidentally similar sequence is also repressed

CRISPR

Clustered Regularly Interspaced Palindromic Repeats’ prokaryotic mechanism that cleaves invading DNA in a double-strand break

CRISPR Process

sequences separated by spacers and found in cluster; cluster is transcribed, processed and then binds to Cas9; complex finds target and Cas9 cuts it

spacers

segments of foreign DNA saved to transcribe RNAs to guide RNAs and bind with Cas9 to find and cut the foreign DNA

uses of CRISPR

modify Cas9 so it guides RNA without cutting; can target mutations in the gene to be made, silence gene expression; replace defective genes with good copies; crop and animal mods

GMO

genetically modified organism whose material has been altered by unnatural genetic engineering

use of GMO

improved ability to grow, improved ability to harvest or store; improved nutritional value; cost savings

Bt Corn

corn borers destroy corn; Bt from soil bacteria is injected into corn and kills corn borer

rainbow papaya

ringspot virus wiped out papaya until they inserted viral genes encoding capsid proteins making it resistant

golden rice

rice is low in beta-carotene, crucial for vitamin A; initially tried daffodils but still not enough vitamin A, so they made it with Psy gene from corn

GMO Risks

\-some are untested and very new

\-food web risks

\-allergic reactions/toxicity?

genetic pest management

reduce economic loss, combat invasives, decrease human disease

gene drive

element passed from parent to progeny at a higher frequency that expected with normal genetics; red flour beetle and new world screwworm

euthenic

provide opportunities and experiences to improve quality of life without regard to genotype

euphenic

altering phenotypes of individuals to improve their quality of life

eugenic

altering the gene pool to increase the frequency of good genes and decrease the frequency of bad genes

negative eugenics

restrict reproduction of the “inferior”

positive eugenic

encourage the “superior” to reproduce more

genetic counseling

helping people understand and adapt to genetic disease

non directive

genetic counseling is informing patients not suggesting or pushing and allowing family to make their own decisions

prenatal

preconception to birth; usually trying to conceive; high risk pregnancies, anomalies on ultrasound, fertility problems

screening test

provide as est. of the risk of a particular disorder

diagnostic test

provide specific definitive diagnosis; CVS and amniocentesis

microarray

can diagnose more specific dn alterations not seen on a karyotype

pediatric

birth to adulthood; developmental delays, dysmorphic features, NICU and PICU, autism

cancer

individuals with a personal or family history of cancer

SNP (single nucleotide polymorphism)

specific site on the genome where DNA varies in at least 1% of the population; can sometimes correlate presence of a genetic disorder

tagSNPs

a few SNPs used to identify a haplotype, often inherited together

gene chip

probes on chip bind to matching SNPs and computer will say which are present

ecogenetics

study of genetic variation that impacts responses to environmental chemicals; risk depends on transport, metabolism and excretion of the chemical

parathion

common pesticide that is broken down into a toxic chemical (paraoxon), causes a disruption of nerve signal transmission

tamoxifen

used after breast surgery to reduce the reoccurrence of cancer, mimics estrogen but does not stimulate cell division

precision medicine

allows for more catered medicine for your genotype

Direct to Consumer Testing (DTC)

DNA tests allowing people to gain insight about their genetics and various health conditions; uses gene chips to identify SNPs

GINA 2008

health insurance companies and employers cannot discriminate based on genetic testing and they cannot require genetic testing

STR (short tandem repeat)

polymorphic characteristics, unlikely two people will have the same profile if multiple are used

Combined DNA Index System (CODIS)

FBI DNA database that uses 20 polymorphic regions for forensic ID

capillary electrophoresis

can test for multiple genes in one run unlike gel electrophoresis; computer analyzes multiple loci

Innocence Project

DNA evidence used to exonerate people falsely convicted of crimes

PCR Polymerase Chain Reaction

Kary Mullis developed it; denature DNA, primers anneal to identify target that will be amplified; taq polymerase adds nucleotides to 3’ end

Limitations of PCR

must know some of the surrounding gene of interest; easily contaminated from other DNA in lab; taq does not proofread or correct errors

electrophoresis

DNA is negatively charged; separates DNA based on size, small pieces move fast/ farther than big pieces

cancer cells have…

uncontrolled cell division and the ability to metastasize

G1/S Checkpoint

monitors for proper cell size and undamaged DNA

G2/M Checkpoint

holds up cycle until replication and repair are complete

M checkpoint

proper spindle formation and attachment

cancer

mass of tissue with unlimited potential to divide and serving no function in the body

leukemias

large number of leukocytes made by bone marrow, common in children

Lymphomas

•Abnormally large number of lymphocytes (type of WBC) made by spleen and lymph nodes

carcinomas

Solid tumor from epithelial tissue; skin, breast, colon, urinary

Sarcomas

•Solid tumors from embryonic mesoderm tissue; bone, cartilage, muscle, fat

miscellaneous

mixed tissues cancer, testicular or ovarian cancers

hyperplasia

uncontrolled cell division, immortal and invasive

anaplasia

structure/function of cell is undifferentiated

metastasis

ability to move to and establish tumors at other sites

tumor

distinct mass of abnormal cells that do not have normal controls on cell division

benign

abnormal cells remain localized and do not invade surrounding tissue

malignant

cancer cells invade surrounding tissue

metastatic

cancer cells spread and establish secondary tumors in other sites in the body

carcinogens

cause mutations and alter gene expression

multi-hit disease

cancer is mostly sporadic and influenced by environment; develop over time with multiple genetic changes

tumor suppressor gene

prevent bad cells from dividing; recessive (must disrupt both regulation genes)

proto-oncogenes

allow good cells to divide

mutation at protein level

loss of function→ recessive acting mutations

gain of function→ dominant acting mutations

retinoblastoma RB

tumor suppressor; Knudson’s two hit hypothesis (both must be defective for tumor to develop)

BRCA1 and BRCA2

tumor suppressor; repairs double strand breaks; account for most breast cancers

haploinsufficiency

diploid organism has a loss of function of one copy of a gene and is left with only one copy, does not produce enough gene product to be normal

bloom syndrome

defective DNA helicase enzyme that is supposed to repair double strand breaks; can still be impacted even if they have a normal copy of the gene

oncogene

uncontrolled cell division, dominant; burkitt’s lymphoma, chronic myelogenous leukemia

burkitt’s lymphoma

abnormal function of b cells, reciprocal translocation of chr. 8 and 14

chronic myelogenous leukemia

reciprocal translocation of chr. 9 and 22; fatal replication of myeloid cells

viruses that cause cancer

epstein-barr virus, hep. B virus, human papilloma virus (HPV)

palladin gene

codes for cytoskeleton protein; cells that metastasize usually have poor cytoskeleton structure, causing them to detach from tumor easily

clonal evolution

tumor cells acquire more mutations w time and progressively get more aggressive

dan repair in cancer

* defective nucleotide excision repair→ no repaired pyrimidine dimers
* defective mismatch repair→ results in stomach cancer
* defective double strand break→ BRCA1 and 2

telomere length in cancer

cancer cells have longer than expected telomere length

angiogenesis

growth of new blood cells; leads to tumor progression

stem cells

\-divide continuously in culture (immortal)

\-produce more cells like itself

\-ability to differentiate into specialized tissue

embryonic stem cell

have potential to differentiate into many tissue types (pluripotent)

adult stem cell

more limited to the types of tissue it can become; multipotent

signal transduction genes

tell the cells what kind of tissue to become

stem cells can potentially treat…

alzheimer, parkinson, diabetes, spinal chord injuries, etc.

how to get adult stem cells

umbilical cord at delivery, bone marrow of adult, amniotic fluid

how to get embryonic stem cells

from blastocyst of early embryo

therapeutic cloning

uses patient’s cells to insert into an enucleated donor egg

induced pluripotent stem cells (iPS)

creating stem cells without using eggs or embryos; use of retrovirus to insert DNA into a cell’s chromosome to make the cell less differentiated

autograft

donate to yourself; i.e. a severe burn

isograft

transplant between identical twins

allograft

one person gets a transplant from another person

xenograft

uses tissue from another species such as a heart valve transplant using a pig

HLA loci

greater transplant success if math at HLA loci; very unlikely that 2 unrelated people match at all 6 of the genes

Human Leukocyte Antigen

tissue carry antigens that can cause antibody formation in recipient; rejecting transplants as foreign in their body

issue w/ organ transplants

who gets priority?