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cancer is a

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phenotype produced by the environment and the genotype

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cancer affects

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many different cells and tissues in the body

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cancer is cell division

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out of control

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spread to other sites

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metastasize

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process of metastasis

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1. cancer cells break away from their home tissue 2. the metastasizing cells become attached to the wall of a blood vessel or lymph vessel. they secrete digestive enzymes onto it. then they cross the wall at the breach 3. cancer cells creep or tumble along inside blood vessels, then leave the bloodstream the same way they got in. they start new tumors in new tissues

question

cancer can be ______ or ______

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inherited susceptibility; a sporadic event

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sporadic is the _____ common cancer

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most

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those with the mutant allele causing predisposition to cancer have a ______ fold increased risk

answer

100,000

question

evidence that cancer is genetic in origin

answer

1. more than50 forms have some degree of inherited predisposition 2. most carcinogens are also mutagens 3. some viruses carry mutant genes (oncogenes) that promote and maintain growth of a tumor 4. specific chromosomal changes are found in some cancers

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oncogenes

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mutant genes

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cells in tumors are descended from a _____ cell

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single

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most cancers develop after

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a cell accumulates a number of specific mutation over a long period of time

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once formed, cancer cells divide

answer

continuously

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when mutations continue to accumulate, the cancer becomes

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more aggressive

question

cancer cells are

answer

invasive

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sporadic may be cause by a ________ or ______

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single dominant mutation; a number of recessive mutations in a somatic cell

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_______ is the leading risk factor for many cancers because ________

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age; cancer causing mutation accumulate over time

question

cancer cells have _____ shapes

answer

abnormal

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cancer cells bypass _______ in the cell cycle

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checkpoints

question

tumor suppressor genes

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suppress cell division; act at either G1/S or G2/M control points

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proto-oncogenes

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promote cell division if mutation

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oncogenes

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mutant forms of proto-oncogenes induce or continue uncontrolled cell division

question

retinoblastoma

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cancer of the retina

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retinoblastoma is diagnosed between ages

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1-3

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40% of retinoblastoma cases are due to

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autosomal dominant trait

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60% of retinoblastoma cases are due to

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sporadic cases

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hereditary retinoblastoma

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autosomal dominant; individuals with allele, RB have 90% chance of developing; both eyes; high risk of other cancers like osteosarcoma and fibrosarcoma

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sporadic form of retinoblastoma

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mutations occur in both copies of the RB1 gene at 13q14; tumors form generally in one eye; no increased risk of other cancers

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knudson two-step model

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disease develops when two mutant copies of RB1 are present in the cell; inherited retinoblastoma= a child inherits one mutant allele and it the normal copy becomes mutated then retinoblastoma develops; sporadic form= both copies must become mutated to develop the disease, generally only in one eye and later in childhood

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RB1 Gene

answer

located at 13q14 and encodes for protein pRB

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pRB regulates

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the cell cycle; present in most cells; activated pRB prevents the cell from moving from G1 to S

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if both copies of the RB1 gene are deleted or mutated the cell divides in an

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uncontrolled manner

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proto-oncogenes

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turn on or off cell division

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oncogenes

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permanently switch on cell division

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ras proto-oncogene receives and transfers signal needed for

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cell division

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breast cancer

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most common form of cancer in US women, but also found in men

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40,000 deaths/year and 180,000 new cases/year are due to

answer

breast cancer

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5% of breast cancer cases are due to

answer

BRCA1 gene (while the rest are sporadic)

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1/200 women inherit the allele for _____ and 90% develop it

answer

breast cancer

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Mary-Clair King began research on _____ in 1970s and in 1990 found linkage with a variable-number tandem repeat (VNTR) on the ______ marker

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BRCA1 gene;183rd

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the 183rd marker is also linked to

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ovarian cancer

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the autosomal dominant BRCA1 gene was identified in

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1994

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BRCA1 is on chromosome

answer

17

question

BRCA2 is mapped on chromosome

answer

13

question

BRCA1 and BRCA2 account for ____ % of breast cancer

answer

10

question

allele frequencies of BRCA1 and BRCA2 vary among

answer

populations

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BRCA1 and BRCA2 expression is highest at the ____ boundary and the _____ phase of the cell cycle

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G1/S; S

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BRC1 protein is activated when

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DNA is damaged

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BRC1 is involved in the repair of double stranded breaks in

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DNA

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BRCA2 protein is similar in function to ______ and is regarded as a ______

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BRC1; tumor suppressor gene

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colon cancer

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84% sporadic forms; common form

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2 forms of genetic predisposition to colon cancer:

answer

1. familial adenomatous polypoisis (FAP) accounts for 1% of all cases 2. hereditary nonpolyposis colon cancer (HNPCC) accounts for 15% of all cases

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FAP

answer

autosomal dominant; mutation of APC gene; 3/1,000; develops polyps and benign growths in the colon; polyps become malignant

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chromosomal site of mutation for Wilms tumor

answer

11p13

question

minimal number of mutations required to develop Wilms tumor

answer

2

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colon cancer chromosomal site of mutation

answer

5q, 12p, 17p, 18q

question

colon cancer minimal number of mutations required

answer

5 to 7

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small-cell lung cancer chromosomal sites of mutations

answer

3p, 11p, 13q, 17p

question

small-cell lung cancer minimal number of mutations required

answer

10 to 15

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retinoblastoma chromosomal sites of mutation

answer

13q14

question

retinoblastoma minimal number of required mutations

answer

2

question

2 forms of hereditary nonpolyposis colon cancer and function

answer

HPNCC1 (2p16) and HPNCC2 (3p23-21.3); to repair error during DNA replication

question

microsatellites

answer

numerous mutations in DNA sequences causes by mutations that destabilize the genome

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HNPCC tumors may carry more than ______ mutation

answer

100,000

question

Hereditary nonpolyposis colon cancer caused ________ risk of many other cancers

answer

increased

question

2 types of genes involved with cancer

answer

gatekeeper genes; caretaker genes

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gatekeeper genes

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regulate cell growth and passage through cell cycle (ex. tumor suppressor genes and some oncogenes)

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caretaker genes

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help maintain the integrity of the genome (ex. DNA repair genes)

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Disorders associated with chromosomal instability and cancer susceptibility

answer

bloom syndrome, ataxia telangiectasia,, fanconi anemia, xeroderma pigmentosum

question

philadelphia chromosome

answer

abnormal chromosome produced by a translocation between long arms chromosome 9 and chromosome 22; linked to chronic myelogenous leukemia (CML)

question

translocation

answer

chromosomal breaks that can convert proto-oncogenes to oncogenes

question

In CML the oncogene c-abl on chromosome 9 at the breakpoint the bcr gene is on chromosome 22 at the breakpoint. this translocation makes a _______ gene

answer

hybrid

question

producing a hybrid protein that acts as a signal for cell division causes

answer

CML

question

traditional cancer therapy

answer

chemo and radiation therapy

question

chemo and radiation target

answer

all rapidly dividing cells and creates serious side effects

question

Gleevec

answer

new drug that targets specific hybrid protein

question

epidemiological studies identify

answer

variation in cancer deaths between populations and help identify environmental factors

question

skin cancer is the

answer

most common form of cancer

question

Americans have a ______ lifetime risk of getting skin cancer

answer

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Chapter 12: Genetics and Cancer – Flashcards

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