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40 Cards in this Set

  • Front
  • Back

Empiric risk is based on ______, which is the ___________.

incidence; rate at which a certain event occurs

To date, the most informative studies on how and to what degree heredity and the environment influence human traits have relied on data from

monozygotic twins separated at birth

People with very light skin have _________

about the same number of melanocytes as people with very dark skin

Mutations and SNPs are similar in that

they can both be changes in a DNA sequence

Multifactorial traits include

both single gene and polygenic traits

If a trait has a large inherited component, then concordance among monozygotic twins will be

considerably higher than that of dizygotic twins

Genes that help to control body weight encode the proteins

leptin, ghrelin, and the melanocortin-4 receptor

Heritability refers to

the genetic contribution to a phenotype in a population at a particular time

Geneticists designate heritability as "narrow" or "broad" to account for the fact that

genes contribute to different degrees. Typically, dominant alleles are rare and can have a large impact and recessive alleles tend to be common with minor but additive effects

The DNA of dizygotic twins is

as alike as the DNA of any two full siblings

Studies that implicate the environment in influencing body weight consider

populations that split, with some people remaining in the homeland and others moving to areas where their diet changes dramatically, and they gain a great deal of weight

Traits that have both inherited and environmental causes are termed

multifactorial

Heritability of a trait can change because

the environment can change

Total ridge count" is

a multifactorial trait that considers the number of ridges in whorls, loops, or arches of the finger pad skin

Mendel's laws

apply to multifactorial traits but may be difficult to follow because different genes contribute in different degrees to a phenotype

An assumption of twin studies is that

both twins of a pair have had similar experiences

The distinction between multifactorial and polygenic traits is that

polygenic traits are caused by more than one gene, and multifactorial traits are caused by one or more genes as well as environmental influences

A continuously varying trait is

height in humans

The number of genes that affect skin, hair, and eye color is about

100

Traditional ways of evaluating multifactorial traits include

empiric risk and heritability

The empiric risk to a family member of an affected individual developing a disorder caused by a multifactorial trait

increases with increasing relatedness to affected individuals

Genome-wide association studies have identified approximately __ regions that appear to harbor genes that control body weight

50

Mutations and SNPs are different in that

mutations are rare and typically have a large effect on a phenotype, whereas SNPs are common and each may contribute a small degree to a phenotype

A brother and sister share ___ percent of their genes

50

In humans, heritability of clubfoot is 0.8. This means that expression of this condition is

also influenced by environmental factors

The empiric risk that the monozygotic twin of a person with cleft lip also has cleft lift is ___ times the risk to a member of the general population who has no relatives with cleft lip

400

Two brothers share ___ percent of their genes

50

In a polygenic trait

genes contribute to varying degrees, and alleles have differing degrees of impact

The proportion of shared genes between a grandparent and grandchild is ___ percent

25

The coefficient of relatedness indicates

the proportion of genes that types of relatives share

Polygenic traits are

determined by more than one gene

Fingerprint pattern is inherited, but also affected by the environment. An example of how the environment naturally can alter fingerprint pattern is

a fetus touching the developing toe and finger pads to the wall of the amniotic sac

For a multifactorial, polygenic trait, the characteristic shape of the mathematical plot of frequency for each phenotype class is

a bell curve

Skin color is not a good way to distinguish "races" of people because

it is but one of many traits that vary within and between human populations

A cohort study looks at

a large group of people over time, keeping track of specific health conditions or measures

The pattern of genetic transmission typical of a multifactorial trait is

continuous variation of phenotypic expression

Concordance refers to

percentage of twin pairs in which both express a trait among pairs in which at least one twin has the trait

Average height of college students increased throughout the 20th century because

nutrition improved greatly in that time

DNA sequences that contribute to polygenic traits are called

quantitative trait loci

Rasheed suffers terrible migraine headaches. They are likely caused by

at least three genes and perhaps an environmental trigger, such as a food