Lecture--Chapter 23

Question 1

Approximately ___ recognised human genetic diseases

Answer 1

12,000

Question 2

Many other diseases that involve multiple genes and have a complex pattern of inheritance:

Answer 2

diabetes, asthma, mental illness, cancer

Question 3

Several hundred genetic tests in clinical use for:

Answer 3

1. sickle-cell anemia
2. Huntington disease
3. cystic fibrosis
4. predisposition to certain forms of cancer

Question 4

When an individual exhibits a disease, the disorder is more likely to occur in:

Answer 4

blood relatives than in the general population

Question 5

The disease is more common in ___ twins than in ___ twins.

Answer 5

identical; fraternal

Question 6

The disease does not spread to individuals:

Answer 6

sharing similar environmental situations

Question 7

Different populations have:

Answer 7

different frequencies of the genetic disease

Question 8

The genetic disease tends to develop:

Answer 8

at a characteristic age (onset)

Question 9

The human disorder may resemble a genetic disorder that is:

Answer 9

already known to have a genetic basis in an animal

Question 10

A correlation is observed between a disease and:

Answer 10

a mutant human gene or a chromosomal alteration

Question 11

The pattern of inheritance of monogenic disorders can be deduced by

Answer 11

analysing human pedigrees

Question 12

Affected offspring often have:

Answer 12

two unaffected parents

Question 13

When two unaffected heterozygotes have children:

Answer 13

25% of children will have the disease

Question 14

Two affected individuals will have:

Answer 14

100% affected children

Question 15

The trait occurs with the same ___ in both sexes.

Answer 15

frequency

Question 16

often result from loss-of-function mutations

Answer 16

autosomal recessive alleles

Question 17

Autosomal dominant inheritance: common features: affected offspring usually have

Answer 17

one or both affected parents

Question 18

Autosomal dominant inheritance: common features: a heterozygous affected individual will have

Answer 18

50% affected offspring

Question 19

Autosomal dominant inheritance: common features: two affected, heterozygotes will have

Answer 19

25% unaffected offspring

Question 20

Autosomal dominant inheritance: common features: the trait occurs with the same ___ in both sexes

Answer 20

frequency

Question 21

Autosomal dominant inheritance: common features: for most dominant disease-causing alleles, the homozygote is

Answer 21

more severely affected with the disorder

Question 22

a single gene copy does not result in a normal phenotype

Answer 22

haploinsufficiency

Question 23

new acquired function

Answer 23

gain of function mutation

Question 24

altered gene product is antagonistic to normal gene product

Answer 24

dominant negative mutation

Question 25

tests to find out if an individual has a genetic abnormality

Answer 25

genetic testing

Question 26

Pregnant women over 35 years of age are screened routinely to see if they are:

Answer 26

carriers of chromosomal abnormalities

Question 27

sample amniotic fluid, culture the fetal cells, and test

Answer 27

amniocentesis

Question 28

testing of a population for a genetic abnormality

Answer 28

genetic screening

Question 29

single-gene mutations often affect:

Answer 29

protein functions or presence

Question 30

The most common class of human genetic abnormality is a change in:

Answer 30

chromosome number

Question 31

About ___ Americans are diagnosed with cancer each year.

Answer 31

1 million

Question 32

About _____ Americans will die from cancer.

Answer 32

500,000

Question 33

5-10% of cancers have a:

Answer 33

genetic predisposition

Question 34

25% of cancers are due to:

Answer 34

viruses

Question 35

65-70% of cancers result from ____ or exposure to _____

Answer 35

spontaneous mutations; carcinogens

Question 36

any environmental agent that causes cancer

Answer 36

carcinogen

Question 37

Most cancers originate from a single cell

Answer 37

clonal origin

Question 38

At the cellular and genetic levels, cancer is a ___ process

Answer 38

multistep

Question 39

Cancers can be staged:

Answer 39

benign, malignant, or metastatic

Question 40

cancer is characterised by:

Answer 40

uncontrolled cell division

Question 41

human cancers are classified according to:

Answer 41

the type of cell that has become cancerous

Question 42

The cell cycle is a series of stages that cells progress through leading up and including:

Answer 42

division

Question 43

any naturally occurring substance that stimulates cell growth, division or differentiation

Answer 43

growth factors

Question 44

____ act as signaling molecules

Answer 44

protein or steroid hormones

Question 45

a skin growth hormone

Answer 45

epidermal growth factor (EGF)

Question 46

genes that promote cancer by keeping a cell growth signaling pathway permanently ON

Answer 46

oncogenes

Question 47

normal genes that can be changed to oncogenes

Answer 47

proto-oncogenes

Question 48

limit the growth of cancer cells

Answer 48

tumor suppressor genes

Question 49

Mutations that occur in tumor suppressor genes that inactivate them make it more likely that:

Answer 49

cancer will occur

Question 50

Cancers most often result from ___ in different ocogenes and tumor suppressor genes.

Answer 50

multiple genetic changes

Question 51

a nucleotide change that encodes a different amino acid

Answer 51

missense mutation

Question 52

carry oncogenes that are expressed during viral replication

Answer 52

acutely transforming viruses

Question 53

inhibit cells from dividing and counteract growth factors; maintain genome integrity

Answer 53

tumor-suppressor genes

Question 54

maintain genome integrity:

Answer 54

check point proteins and DNA repair enzymes

Question 55

About ____ of all human cancers are associated with defects in the ___ gene.

Answer 55

50%; p53

Question 56

Once induced by DNA damage, p53 will:

Answer 56

1. activate genes that promote DNA repair 2. activate genes that arrest cell division and repress genes that are required for cell division 3. activate genes that promote programmed cell death

Question 57

Mutations in BRCA-1 and BRCA-2 account for only:

Answer 57

5-10% of breast cancer

Question 58

Predisposition is inherited in a ___ fashion, with incomplete penetrance.

Answer 58

dominant

Question 59

loss of a functional gene copy

Answer 59

loss of heterozygosity