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86 terms

Chapter 11

STUDY
PLAY
In the mid-19th century, the study of inheritance as a modern branch of science began with the work of..
Gregor Mendel
Offspring from the P generation are heterozygous; they are called the F1 or ________ generation
first filial
Offspring from the F1 cross are called the _______________ generation
second Filial
A ______________ gene may mask the expression of a _______________________ gene.
Dominant; Recessive
During meiosis, members of paired genes at each allele _______________ so that each gamete contains only one allele of each pair.
Segregate
The site of a gene on a chromosome is called its _________
locus
The two chromosomes that make up a pair are called _______________________ chromosomes
homologous
An individual is said to ____________ for a particular feature when the two alleles it carries for that feature are different
heterozygous
A ______________ predicts the ratios of genotypes and phenotypes of the offspring of a cross
punnett square
The phenotype of an individual does not always reveal its _________
genotype
A test cross is a cross between an individual of unknown genetic composition and a ______________________ individual.
homozygous recessive
A dihybrid cross is a cross between individuals that differ with respect to their alleles at _____________
two loci
The mechanics of _______ are the basis for independent assortment
meiosis
The chromosome theory of inheritance can be explained by assuming that genes are ___________________ in specific locations along the chromosomes
linearly arranged
Genes in the same chromosome are said to be ________ and do not assort independently
linked
The sex or gender of many animals is determined by the X and Y sex chromosomes. The other chromosomes in a given organism's genome are called ____________
autosomes
When a Y-bearing sperm fertilizes an ovum, the result is a _________________ and fertilization by an X-bearing sperm produces a ________________
XY zygote; XX zygote
A dense, metabolically inactive X chromosome at the edge of the nucleus in female mammalian cells is known as the ________________
Barr body
In genetic crosses involving _________, the genotypic and phenotypic ratios are identical
Incomplete dominance
Multiple alleles are _____ different alleles that can occupy the same ___________
3 or more; locus
_____________ refers to the many different effects that can often result from a given gene
Pleiotropy
________________ is when one allele of a gene pair detemines whether alleles of other gene pairs are expressed
Epistasis
It is called ____________ when two or more independent pairs of genes have similar and additive effects on a phenotype
polygenic inheritance
The range of phenotypic possibilities that can develop from a single genotype under different environmental conditions is known as the ________________
norm of reaction
Two or more pair of genes that affect the same trait in an additive fashion
polygene
Having the same (identical) members of a gene pair
homozygous
Having dissimilar (different) members of a gene pair
heterozygous
Pertaining to the mating of individuals differing in two specific pairs of genes
Dihybrid
Pertaining to the mating of individuals differing in one pair of genes
monohybrid
Having only half (one) of a given pair of genes
Hemizygous
Condition in which certain alleles at one locus can alter the expression of alleles at a different locus
Epistasis
An alternative form of a gene
allele
The physical or chemical expression of an organism's genes
Phenotype
Condition in which a single gene produces two or more phenotypic effects
pleiotropy
A condensed and inactivated X-chromosome appearing as a distinctive dense spot in the nucleus of certain cells of female mammals
Barr body
the allele that is not expressed in the heterozygous state
recessive allele
The place on a chromosome at which the gene for a given trait occurs
locus
condition in which both alleles of a locus are expressed in a heterozygote
Incomplete dominance
The allele that is always expressed when it is present
Dominant allele
The transmission of genetic information from parent to offspring
heredity
the science of heredity
genetics
The differences between parents and offspring or among individuals of a population
genetic variation
A monk who bred pea plants
Gregor Mendel
First scientist to effectively apply quantitative methods to the study of inheritance
Gregor Mendel
The offspring of two genetically dissimilar parents
hybrid
All hybrids that are the offspring of genetically pure
true breeding (pure breeding)
Refer to the physical appearance of an organism
phenotype
The attributes for which heritable differences
traits
members of two different true-breeding lines that are crossed to produce the F1 generation; parental generation
P generation
the first generation of hybrid offspring resulting from a cross between parents from two different true-breeding lines; first filial generation
F1 generation
The offspring of the F1 generation; second filial generation
F2 generation
the factors expressed
Dominant
the factors that are present but not expressed
Recessive
Part of DNA that serves as a unit of hereditary information
Genes
refers to the alternative forms of a gene
Allele
States that before sexual reproduction occurs, the two alleles carried by an individual parent must become separated
Principle of segregation
originally designated the location of a particular gene on the chromosome
Locus
When two alleles an organism carries for the locus are identical
homozygous
an organism carry two different alleles for the locus
heterozygous
the possible combinations of eggs and sperm at fertilization can be represented in the form of this grid
punnett square
the inheritance of two different alleles of a single locus
monohybrid cross
the genetic constitution of that organism
genotype
an individual of unknown genotype is crossed with a homozygous recessive individual
test cross
a mating between individuals with different alleles at two love
dihybrid cross
states that members of any gene pair segregate from one another independently of the members of the other gene pairs
principle of independent assortment
when alleles do not assort independently and tend to be inherited together
linked genes
the tendency for a group of genes on the same chromosome to be inherited together in successive generations
linkage
the observation of linkage in the results of a test cross and because alleles of two love are involved
two-point cross
any process that leads to new gene combinations
recombination
a chromosome that plays a role in sex determination
sex chromosomes
what the cells of females of many animal species contain
X chromosome
What the cells of males contain
Y chromosomes
Chromosomes other than the sex chromosomes
autosomes
A hormone which causes other male characteristics to develop
testosterone
genes located in the X chromosome
sex linked genes
has only one copy of each X-linked gene
Hemizygous
a condition in which neither member of a pair of contrasting alleles is completely expressed when the other is present
incomplete dominance
condition in which two alleles of a locus are expressed in a heterozygote
codominance
the four blood types
ABO blood groups
the condition which three or more alleles for a given locus exist within the population
multiple alleles
the ability of a single gene to have multiple effects
pleiotropy
a common type of gene interaction in which the presence of certain alleles of one locus can prevent or mask the expression of alleles of a different locus and express their own phenotype instead
epistasis
when multiple independent pairs of genes have similar and additive effects on the same character
polygenic inheritance
A person with one X but no Y chromosome has the overall appearance of a female but has defects such as short statue and undeveloped ovaries
turner syndrome
A person with an XXY constitution is a nearly normal male in external appearance, although his testes are underdeveloped
klinefelter syndrome
the sex reversal on Y gene. the major male-determined gene on the Y chromosome, acts as a "genetic switch" that causes testes to develop in the fetus
SRY gene