• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

Card Range To Study

through

image

Play button

image

Play button

image

Progress

1/163

Click to flip

Use LEFT and RIGHT arrow keys to navigate between flashcards;

Use UP and DOWN arrow keys to flip the card;

H to show hint;

A reads text to speech;

163 Cards in this Set

  • Front
  • Back
The work of body cells is done by ____, under the direction of instructions stored in molecules of __________________, which are stored on _____________.
proteins; DNA;chromosomes
Each normal person inherits ______________ chromosomes, __________from each parent. The genetic instructions in chromosomes are organized into unites called ______________, each of which contains instructions for a specific ___________, which in turn in composed of chemical building blocks called ___________ _____________,__________ and ____________ Some genes come in several slight, normal variations called _________. The sum total of these genetic instructions for a given species is called its __________________.
46;23;genes;protein;amino acids; bases; adenine;thiamine;cytosine;guanine;alleles;genome
The human reproductive cells, which are called _________, include the male's ________ and the female's __________.
gametes;sperm;ovum
When the gametes' nuclei fuse, a living cell called a __________is formed.
zygote
This new cells receives _________-chromosomes from the father and _______________from the mother.
23;we
An organism's entire genetic inheritance is called its _____--.
genotype
The chromosomes in a pair are generally identical or similar. The 44 chromosomes that are independent o fthe sex chromosomes are called __________________. If a gene from one parent is exactly like that from the other parent, the gene pair is said to be _________________. If the match isnot perfect, the gene pair is said to be _________.
autosomes;homozygous;heterozygous
If the chromosomes are books of heredity, the genes that make each of us a distinctive human being are _________ and the DNA molecules are the __________
words,letters
8) The developing person's sex is determined by the ___________pr of chromosomes. In the female, this pair is composed of 2 _______________ shaped chromosomes and is designated ______________. In the male, this par is includdes one __________ and one ______-chromosome and is therefore designated ____________________.
23rd; X; XX; X; Y; XY
9) The critical factor in the determination of a zygote's sex is which _____(sperm/ovum)reaches the other gamete first. The neatural sex ratio at birth is about __________ . In a stressful pregnancy, __________ (xx/xy)embryos are more likely to be miscarried, or _______________ ____________________.
sperm:50;50;XY;spontaneously aborted
10 (Critical Thinking) In countries such as China, prenatal tests that show the sex of the child have been used to ________________. The sex ratio can also be affected by _______pregnancies of the "wrong" sex or by __________--____________ changing the proportion of X and Y sperm before insemination.
abort female fetuses; aborting; sperm-sorting
11) Within hrs after conception, the zygote begins to __________ and ____________ . At about the eight-call stage, the cells start to __________, with varioius cells beginning to specialize the reproduce at different rates. As a result of these processes, cells change from being _______ ________that are able to produce any type of cell to becoming specialized cells.
duplicate;divide;differentiate;stem cells
Identical, or monozygotic, twins, who develop from one __________, _________(are/are not) genetically identical. This occurs about once in every _________(how many?) conceptions.
zygote; are; 250
13)Twins who begin life as two separate zygotes created by the fertilization of 2 ova are called______________ or ____________ , twins.
Such twins have approximately _______- percent of their genes in common.
dizygotic;fraternal;50
14) The incidence of dizygotic births varies by ___________and ___________.
ethnicity;age
15) For infertile couples, medical intervention, or _______ _______ ____________, can help in conceiving and then sustaining a pregnancy.
assisted reproductive technology (ART)
16) One simple treatment for infertility is to use _______to cause ovulation. Another technique, which involves fertilization in a laboratory dish, is called _____-- _____ fertilization. This may be done by inserting a sperm directly into the ovum, a process called _________-________ _________ __________. I f the male partner is infertile, donor sperm may be inserted into the female's uterus in a process formerly called ________ ________.
drugs; in vitro; intra-cytoplasmic sperm injection (ICSI) ; intrauterine insemination
17) (Thinking critically) Developmentalists typically __________(advise/do not advise) infertile couples to want multiple births via IVF. One reason is that muliple-birth babies have higher rates of _____________, ________, and ___________.
do not advise; death; disease; disabilities
18) Concluding her presentation on the hazards of multiple births, Kirsten notes that, "the more embryos that develop together, the"
---- less mature and more vulnerable each is
The more fetuses that share a womb, the smaller, less mature, and more vulnerable each one is. All their lives, multiple-birth babies have higher rates of disease and disabilities.
19) If a dizygotic twin develops schizophrenia, the likelihood of the other twin experiencing serious mental illness is much lower than is the case with monozygotic twins. This suggests that _________________________
---- schizophrenia is influenced by genes.
Because monzygotic twins are genetically identical, while dizygotic twins share only 50 percent of their genes, greater similarity of traits between monzygotic twins suggests that genes are an important influence.
20) The actual appearance and manifest behavior of the person is called the ______________
pheotype
21) Most human characteristics are affected by many genes, and so they are _________, and by many factors, and so they are ____________.
polygenic; multifactorial
22) All important human characteristics are ____________. This idea emphasizes the interaction between _________and the _____________. Some interactions occur in the first hours of life, as biochemical elements since certain _________ in the process called __________.
epigentic; genes; environment; genes; methylations (spelt correctly)
23) The prefix "epi" refers to the various _______-factors that affect the expression of _______- ______. These include factors that can slow development such as _____________________. Others are facilitating factors such as ___________________.
environmental; genetic influences; injury, temperature extremes, drug abuse,and crowding; nourishing food, loving care, and freedom to play.
24) The international effort to map the complete human genetic code, the ___________- _______ _____, was complete in 2001. This effort found that humans have ___________(many more/far fewer) genes than prevously thought. Most importantly they found that all living creatures _____(have different/share) genes. The differences among species are due to the "________________" around the genes and the actions of the ______ genes.
Human Genome Project; far fewer; share; "junk"; regulator
25) A pheotype that reflects the sum of the contributions of all the genes involved in its determinations illustrates the ____pattern of genetic interaction. Examples include genes that affect ____________ and ______- _______.
additive; height; skin color (or hair curliness)
26) Less often, genes interact in a ___________fashion. In one example of this pattern, some genes are more influential than others; this is called the _______ - _______ pattern. In the pattern, the more influential allele is called ________ and the weaker one is called ___________.
nonadditive; dominant-recessive; dominant; recessive
27) A person who has a gene in his or her genotype that is not expressed in the phenotype but that can be passed on to the person's offspring is said to be a _______of the gene.
carrier
28) Some recessive genes are located only on the X chromosome and so are called ______- ________. Examples of such genes are the ones that determine _______________. Because they have only one X chromosome, ___________ females/males) are more likely to have these characteristics in their phenotype
X-linked; color blindness, many allergies, several diseases,and some learning, disabilities; males
29) When genes function differently depending on which parent they came from, the phenomenon known as ___occurs. Examples of this phenomenon include Prader-Willi syndrome and Angelman syndrome
imprinting
30) If your mother is much taller than your father, it is most likely that your height will be
--- somewhere between your mother's and father's height because the genes for height are additive.
Is unlikely that the other factors account for height differences from one generation to the next
31) Some men are color-blind because they inherit a particular recessive gene from their mothers. That recessive gene from their mothers. That recessive gene is carried on the _________chromosome.
X.
Color blindness is X-linked. Since the Y chromosome is much smaller than the X, an X-llinked recessive gene almost never has a dominant counterpart on the Y. Thus, color blindness most often occurs in males.
Winona inherited a gene from her mother that , regardless of her father's contribution to her genotype, will be expressed in her phenotype. Evidentialy, the gene Winona received from her mother is a ____________gene.
dominant.
The dominant gene is always expressed in the person's phenotype. For a recessive gene to be expressed, the individiual must inherit a recessive gene from both parents.
33) State 4 general prinicples of genetic influences on development that virtually all developmentalists accept.
a. Genes affect every aspect of human behavior.
b Most enviromental influences on children raised in the same household are not shared.
c Genes elicit responses from other people that shape each chlld's development
d People of all ages choose friends and environments, in a process called niche-picking, that are compatible with their genes.
34) Without _________, no behavior could exist. Without _______, no gene could be expressed. Some people's inherited biochemistry makes them highly susceptible to various _____________.
genes; environment (context);addictions
35) Certain ________traits encourage drinking and drug taking. These traits include __________ . Two other factors in alcoholism are ________and ________ _____. Women become drunk on __________(less/more) alcohol than men.
personality; a quick temper, sensation seeking, and high anxiety;gender;biological sex; less
36) The percentage of the variation in a trait within a particular population, in a particular context and era,that can be traced to genes is called its _____________.
heritability
37) Like alcoholism vision is also affected by ______, ________ and _____________. The alarming increase in the rate of the vision problem of __________ among children in East Asia has been attributed to the increasing amount of time spent by children in the ________. In other parts of the world, this problem may because by genes or by poor _____________ especially lack of _________ ____.
age; genes; culture; nearsightedness; close study of books and papers; nutrition; vitamin A.
Statistics apply to populations or idividuals?
populations
38) Genetically, Claude's potential height is 6'0. Because he did not eat a balanced diet, however he grew to only 5'9". Claude's actual height is an example of a __________.
pheotype.
The phenotype is the observable characteristics of a person.Genotype is the individual's entire genetic inheritance, or genetic potential.
39) A person's skin turns yellow-orange as a result of a carrot-juice diet regimen. This is an example of ________________.
--an environmental influence
Genotype is a person's genetic potential, established at conception. Polygenic inheritance refers to the influence of many genes on a particular trait. Incomplete dominance refers to the pheontype being influenced primarily, bu not exclusively, by the dominant gene.
40) Laurie and Brad, who both have a history of alcoholism in their families, are concerned that the childthey hope to have will inherit a genetic predisposistion to alcoholism. Based on information presented in the text, what advice should you offer them?
"Social influences, such as the family and peer environment, play a critical role in determining whether alcoholism is expressed."
Despite a strong genetic influence on alcoholism, the environment also plays a critical role
41) Researchers study genetic and chromosomal abnormalities for 3 major reasons. State them
a. They provide insight into the complexities of genetic interactions
b. Knowing their origins helps limit their harmful effects
c. Information combats the prejudice that surround such problems
42) Chromosomal abnormalities occur during the formation of the ____________, producing a sperm or ovum that does not have the normal complement of chromosomes.
gametes
43) One variable that correlates with chromosomal abnormalities is ________ _______.
maternal; age
44) Many fetuses with chromosomal abnormalities are _______ ______________. Nevertheless, about 1 in every ________ newborns has one chromosome too few or one too many, leading to a cluster or characteristics called a _________.
spontaneously aborted; 200; syndrome
45) The most common extra-chromosome syndrome is _______ _____, which is also called _______ ____ . People with this syndrome are usually slower to develop _________, especially in ___________. List several of the physical and psychological characteristics associated with Down syndrome.
Down syndrome; trisomy-21; intellectually; language

Most people with Down syndrome have certain facial characteristics - a thick tongue, round face, slanted eyes - as well as distinctive hands, feet,and finger-prints. Many also have hearing problems, heart abnormalities, muscle weakness, and short stature.
46) About 1 in every 500 infants is either missing a _____chromosome or has three or more such chromosomes. Having an odd number of these chromosomes impairs _____________ and psychosocial development as well as _________ _________.
sex; cognitive; sexual maturation
Most of the known single-gene disorders are _______________(dominant/recessive). Genetic disorders ususally ____________ (are/are not) seriously disabling. Severe dominate disorders are _______(common/rare)because people with these disorders ususally _______(do/do not) have children.
dominant; are not; rare;do not
48)One exception is the central nervous system disease called __________ _____-. Another is a rare but severe form of_______________ disease that causes dementia before age 60.
Huntington disease; alzheimer
49) In some individuals, part of the X chromosome is attached by such a thin string of molecules that it seems about to break off; this abnormality is called __________________ _____.
fragile X
50)Three common recessive disorders that are not sex-liinked are ___________________- ___________ , _____________________, and ____________- __________________ ___________.
cystic fibrosis, thalassemia, sickle-cell anemia
All baby births -- every 30th one is born with a serious ____problem
genetic
Does 'serious" mean "disabling" with talking about genetic problems?
No
51) Which of the following is an inherited abnormality that quite possibly could develop into a recognizable syndrome?
A person inherits an X chromosome in which part of the chromosome is attached to the rest of it by a very slim string of molecules.
This describes the fragile X syndrome. The phenomenon described in
a) Kist befpore dovodomg tp fpr, a s[er, pr pvi,. cprres[pmdomg geme segments of a chromosome pair break off and are exchanged: merely contributes to genetic diversity
b). Just before conception, a chromosome pair splits imprecisely, resultinig in a mixture of cells: is an example of a particular nonadditive gene interaction pattern
d) A person inherits a recessive gene on his Y chromosome for a recessive gene to be expressed, both parents must pass it on to the child.
52) Sixteen yr old Joey experiences some mental slowness and hearing and heart problems, yet he is able to care for himself and is unusually sweet tempered. Joey probably has _____________.
Down syndrome
53) Jason, who is 40 yr old, has just been diagnosed with an inherited, dominant disorder of the central nervous system. Jason most likely would be diagnosed with ______ ____-
Hunting disease
54) Through _________ _______ couples today can learn more about this genes and about their chances of conceiving a chld with chromosomal or other genetic abnormalities
genetic counseling
55) List five situations in which genetic counseling is strongly recommended.
Genetic counseling is recommended for
a) those who have a parent, sibling, or child with a serious genetic condtion
b) those who have a history of spontaneous abortions or stillbirths
c) couples who are infertile
d) couples who are from the same ethnic group, particularly if they are related to each other, and
e) women over age 35 and men age 40 or older.
56) In the U.S. and many other nations, every newborn is tested for ______________a recessive condtion that will result in severe retardation if the common food substance _________ is consumed.
phenylketonuria(PKU); phenylalanine
Progress Test:1) When a sperm and an ovum merge, a one-celled ____________ is formed.
zygote
b & c)The reproductive cellls (sperm and ova), which are also called gametes, are individual entitites.
d) Monozygote refers to one member of a pair of identical twins.
2) Genes are spearate units that provide the chemical instructions that each cell needs to become
--a specific part of a functioning human body.
a. The zygote is the first cell of the developing person.
b. Chromosomes are molecules of DNA that carry genes
d. DNA molecules contain genetic information
3) In the male, the 23rd pair of chromosomes is designated _____; in the female,this pair is designated ______.
XY;XX
4) Because the 23rd pr of chromosomes in females is XX, each ovum carries and
X chromosome
When the gametes are formed one member of each chromosome pair splits off, because in females both are X chromosomes, each ovum must carry an X chromosome.
a,b,&c) The zygote refers to the merged sperm and ovum that is the first new cell of the developing individual
5) When a zygote splits, the two identical, independent clusters that develop become
monozygotic twins
Mono means "one" Thus, monozygotic twins develop from one zygote.
a&c) Dizygotic, or fraternal, twins develop from two zygotes (di)
6) During adulthood, genetic influences on development.
generally increase
7) Most of the known single-gene disorders are
dominant
c&d) Most dominant disorders are neither seriously disablng nor sex-linked.
8) When we say that a characterisitic is multifactorial, we mean that
--many genetic and environmental factors are involved.
ab & d Ploygenic means "many genes" multifactorial mean "many factors," which are not limited to either genetic or environmental factors.
9) Gene are segments of molecules of
deoxyribonucleic acid (DNA).
a. Genotype is a person's genetic potential
c. A karyotype is a picutre of a person's chromosomes.
d. Phenotype is the actual expression of a genotype
10) In the United States, newborns are tested for the recessive genetic disorder
phenylketonuria
11) A genetic disorder that is "donminant is one that is
always expressed.
c&d) The text does not indicate a gender difference in dominant genetic disorders.
12) Some developmentalist believe that the epidemic increase in nearsightedness among, children in Hong Kong, Singapore, and Taiwan is partly the result of
--the increasing amount of time spent by children in close study.
a. Rubella has not been mentioned as a major reason for the recent increase nearsighted ness in these countries.
b. Vitamin A deficiencies may be a factor in the vision problems of chilren among certain African ethnic groups.
d. The rapid changes in the prevalence of nearsigntedness suggest that an environmental factor is the culprit.
13) Babies born with trisomy 21 (down syndrome) are often
born to older parents.
14) To say that a trait is polygenic means that
several genes must be present for the individual to inherit the trait
15) Some genetic diseases are recessive, so the child cannot iniherit the condition unless both parents.
-- carry the same recessive gene
a. Huntiniton disesase is a dominant-gene disorder.
c. Age is not a factor in recessive-gene dis-orders.
d.For an offspring to inherit a recessive condtion, the parents need only be carriers of the recessive gene in their genotypes; they need not actually have the disease.
1)gamets
chromosome pair inherited by genetic female
2) chromosome
a DNA molecule
3) genotype
a preson's entire genetic inheritance
4) pheontype
the behavioral or physical expression of genetic ptential
5) monozygotic
identical twins b
6) dizygotic
fraternal twins f
7) additive
a pattern in which each gene in question makes an active contribution to the final outcome. g
8) fragile X syndrome
a chromosomal abnormality j
9) carrier
a person who has a recessive gene in his or her genotype that is not expressed in the phenotype e
10) zygote
the first cell of the developing person d
11) alleles
alternate versions of a gene k
12)XX
chromosome pair inherited by genetic females a
13) XY
chromosome pair inherited by genetic males. l
Progress TEst 2: 1) Which of the following provides the best broad description of the relationship between heredity and environment?
heredity directs the individual's potential, and environment dietermines whether and to what degree the individual reaches that potential.
2) If a man carries the recessive gene for cystic fibrosis and his wife does not, the chance of their having a child with cystic fibrosis
is zero
Cystic fibrosis is a recessive-gene disorder; therefore, for a child to inherit this disease, he or she must receive the recessive gene from both parents.
3) The fetal central nervous system disorder caused by a genetic miscode is
Huntington disease
A. Albinism is a skin disorder
B. Cystic fibrosis affects mucose membranes, expecially in the lungs.
d. Muscular dystrophy causes a weakening of themuscles
b.4) With the exception of sperm and egg cells, each human cell contains
46 chromosomes
a&c) Human cells contain thousand of genes
5) Most recessive disorders are
not sex-linked.
a,b,d: Most recessive disorders are on the autosomes and are not sex-linked
6) Dizygotic twins result when
two eggs are fertilized by two differnt sperm
A. This would result in monozygotic twins
B. Only one sperm can fertilize an ovum
D. A single egg fertilized by one sperm would produce a single offspring or monozygotic twins.
7) Molecules of DNA that is humans are organized into 23 complementary pairs are called
chromosomes
Zytoes are fertilized ova
Genes are the smaller units of heredity that are organized into sequences on chromosomes.
Ova are female reproductive cells
8) Shortly after the zygote is formed, it begins the processes of duplication and division. Each resulting new cell as
the same number of chromosomes as was contaiined in the zygote.
9) If an ovum is fertilized by a sperm bearing a Y chromosome
a male will develop.
The ovum will contain an X chromosome; with the spren's Y chromosome, it will produce the male XY pattern.
a. Onely if the ovum is fertilized by an X Chromosome from the sperm will a female develop.
b. Cell division will occur regardless ofwhether the spserm contributes an X or a Y chromosome
d. Spontaneous abortions are likely to occur when there are chromosomal or genetic abnormalities; the situation described is perfectly normal.
10) When the male cells in the testes and the female cells in the ovaries divide to produce gametes, the process differs from that is the production of all other cells. As a result of the different process, the gametes have
one rather than both members of each chromosome pair.
b&d)These are true of all body cells except the gametes.
c. Gamets have either X or Y chromosomes
11) Most human trait are
polygenic and multifactorial
12) Genotype is to phenotype as ____ ______is to ___________.
gentetic potential;physical expression
Genotype refers to the sum total of all the genes a person inherits; phenotype refers to the actual expression of the individual's chracterisitics.
13) The genes that influence height and skin color interact according to the _____pattern.
additive
14)X-linked recessive genes explain why some traits seem to be passed from
mother to son
Xlinked genes are located only on the X chromosome. Because males inherit on one X chromosome, they are more likely than female to have these characteristic in their phenotype.
15) in vitro fertilization is a techique
in which sperm are mixed with ova that have been surgically removed from a woman's ovary.
b. This describes intrauterine insemination.
c&d) These answers , which are too general, describe all forms of assisted reproductive technology.
T/F 1) Most human characterisitics are mulitifactorial, caused by the interaction of genetic and environmental factors.
T
2) Most dominant disorders are sex-linked T/F
F
Since these disorders appear in the pheontype, they would have to occur only in males to be sex-linked
3) Research suggests that susceptibility to alcoholism is at least partly the result of genetic inheritance. T/F
T
4) The human reproductive cells (ova and sperm) are called gametes. T/F
T
5) Only a very few human traits are polygenic. T/F
F most ratis are polygenic
6) The zygote contains all the bilogically inherited information -the genes and chromosomes - that a person willl have during his or her life.
T
7) A couple should probably seek genetic counseling if several earlier pregnancies ended in spontaneous abortion. T/F
T
8) Many genetic conditions are recessive; thus, a child will have the condtion even if only the mother carries the gene. T/F
F
A trait from a recessive gene will be part of the phyenotype only when the person has two recessive genes for that trait
9) Two people who have the same phenotype may have a different genotype for a trait such as eye color. T/F
T
10) When cells divide to produce reproductive cells (gametes), each sperm or ovum receives only 23 chromosomes, half as many as the original cell. T/F
T
11) Most genes have only one function.
F
Most genes have several functions
Key Terms: 1) deoxyribonucleic acid (DNA)
is the chemical composition of the molecules that contain the genes,which are the chemical instructions for cells to manufacture various proteins.
2) chromosome
are molecules of DNA that contain the genes organized in precise sequences. Each cell contains 46 chromosomes (23pr).
3) gene
are segments of a chromosome, which is a DNA molecule; they are the basic units for the transmission of hereditary instructions.
4) allele
is one of the normal versions of a gene that has several possible sequences of base pairs.
5) genome
is the full set of genes that are instructions to make an individual member of a certain species.
6) zygote
is a single cell formed during conception by the fusing of two gametes. asperm and an ovum.
7) gamete
are the human reproductive cells.
8) genotype
The total of all the genes a person inherits - his or her genetic potential- is called genotype
9) homzygous
refers to two genes of one pr that are exactly the same in every letter of their code.
10) heterozygous
refers to two genes of one pr that differ in some wya.
11) 23rd pr
The 23rd pr of chromosomes, in humans, determines the individual's sex.
12) XX
XX is the 23rd chromosome pr that, in humans, determines that the developing fetus will be female
13) XY
XY is the 23rd chromosome pr that , in humans, determines that the developing fetus will be males
Cross Check 2) Cluster of ditinct characterisitics that then to occur together in a given disorder.
syndrome
7) An organism's entire genetic inheritance.
genotype
8) The single cell formed from the fusing of an ovum and a sperm.
zygote
11) The stronger gene in an interactiong pair of genes
dominant
12) All the gentic traits that are expressed in a person.
phenotype
14) Genes that are on the X chromosome.
X-linked
15) The sequence of chemical bases held within DNA molecules that directs development.
genetic code
16) One of the 46 in each normal human cell
chromosome
17) The genes that affect height, hair curliness, and skin color are of this type.
additive
Key terms 14) stem cell
is one from wozygotic wins which any other specialized type of cell can form.
15) monozygotic (MZ)twins
develop from one zygote that splits apart, producing genetically identical zygotes; also called identical twins. Memory aid: Mono means "one"; monozygotic twins develop from one fertilized ovum
16) dizygotic (DZ)twins
develop from two separate ova fertilized by differnt sperm at roughly the same time, and therefore are no more genetically similar than ordinary siblings; also called fraternal twins. Memory aid: A fraternity is a group of 2 (di) or more nonidentical individuals.
17) assisted reproductive technology (ART)
refers to the various techniques available to help infertile couples conceive and sustain a pregnancy.
18) in vitro fertilization (IVF)
is a form of ART in which ova surgically removed from a woman are mixed with sperm. If a zygote is produced, it is inserted in the woman's uterus,where it may implant and develop into a baby.
19) phenotype
The physical or behavioral expression of a genotype, the result of the interaction of the genes with each other and with the environment.
20) polygenic
Most human traits are polygenic; that is, they are affected by many genes.
21) mulitfactorial
Most human traits are also mulitfactorial -- that is, influenced by many factors, including gentic and environmental factors.
22) epigenetic
refers to environmental factors that affect how genes are expressed.
23) Human Genome Project
an international effort ot map the complete human genetic code, was essentially completed in 2001.
24) dominant-recessive pattern
is the interaction of a heterozygous pair of alleles in such a way that the pheotype reveals the influence of the dominant gene more than that of the recessive gene.
25) carrier
A person who has a recessive gene that is not expressed in his or her phenotype but that can be passed on to the person' off spring is called a carrier of that gene.
26) X-linked
X-linked genes are genes that are located only on the X chromosome. Because males have only on X chromosome, they are more likely than females to have the characterisitics determined by these genes in their
phenotype.
27) heritability
is a statistic that refers to the percentage of variation in the particular trait within a particular population, in a particular context and ear, that can be tracted to genes.
28) Down syndrome
(trisomy-21) is the most common extra-chromosome condition. People with Down syndrome age faster than others, often have unusual facial features and heart abnormalities, and are usually slower to develop intellectually.
29) fragile Xsyndrome
is a single-gene disorder in which part of the X chromosome is attached by such a thin string of molecules that it seems about to break off. Although the characteristics associated with this syndrome are quite varied, some mental definciency is relatively common.
30) gentic counseling
involves consultations and tests through which couples can learn more about their genes, and can thus make informed decisions about their childbearing the child-rearing future.
31) phenylketonuria (PKU)
is a genetic disorder in which the body cannot metabolize the amino acid phenylalanine, which is found in many foods.
Down 1) A genetic disorder in which part of the X chromosome is attached to the rest of it by a very slim string of molecules.
fragile x
3) Fraternal twins.
dizygotic
4) All thenongentic factors that can affect development
environment
5) The growth process in which cells begin to specialize, taking different forms and dividing at different rates.
differentiation
6) The basic unit of genetic instruction.
gene
9) The international project ot map the complete human genetic code.
Human Genome
10) Type of trait produced by the interaction of many genes (rather than by a sing gene).
polygenic
11) Themost common extra-chromosome syndrome (also called trisomy-21)
down syndrome
13) The weaker gene in an interacting pair of genes.
recessive