Set 7 - Chapter 9 - Part 2- Classical Genetics - Barron's

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Question Answer
The father of Modern GeneticsGregor Mendel
___________ is the likelihood that a particular event will happen. It cannot predict whether a particular event will actually occur. However, if the sample is large enough, it can predict an average outcome.Probability
Alternate forms of a gene Alleles (Example: there are two alleles for height in peas plants, tall and short)
The traits that an organism expresses (What the organism looks like)Phenotype
The kind of genes an organism has (type of gene)Genotype
Refers to having identical alleles for a single trait.The genotype letters are identical (For ex: RR or rr)Homozygous
If the genotype letters are RRHomozygous dominant
If the genotype letters are rrHomozygous recessive
A pair of genes where one is dominant and one is recessive. The genotype letters are different (For ex: Rr)Heterozygous
Mendel's first lawLaw of dominance
when two organisms, each homozygous (pure) for two opposing traits are crossed, the offspring will be hybrid (carry two different alleles) but will exhibit only the dominant trait. The trait that remains hidden is known as the recessive trait.Law of dominance
The law which states that during the formation of gametes, the two traits carried by each parent separate. The law of segregation
The cross that best exemplifies the law of segregation is the ___________, Tt X Tt. In this, a trait that was not evident in either parent appears in the F, generation.Monohybrid cross
A cross between two organisms that are each hybrid for a single trait, such as Tt x Tt. Monohybrid cross
The phenotype ratio/percentage and the genotype ratio/percentage for a monohybrid crossThe phenotype ratio from this cross is 3 tall to 1 dwarf plant. 75% tall plants to 25% dwarf plants. The genotype ratio is 1:2:1. 25% homozygous dominant (TT) to 50% heterozygous (Tt) to 25% homozygous recessive (tt)
If the phenotype ratio of the off-spring is 3 to 1, both parents were ___________ for the trait. hybrid
A way to determine whether an individual plant or animal showing the dominant trait is homozygous dominant (BB) or heterozygous (Bb).Backcross or testcross
If the phenotype ratio of the off-spring is 1 to 1, one parent was ___________ and one parent was ___________. hybrid, pure recessive
The law which states that during gamete formation, the genes for one trait (such as height, T or t) are not inherited along with the genes for another trait (such as seed color, Y or y).The law of independent assortment
The law of ___________ applies when a cross is carried out between 2 individuals that are hybrid for 2 traits on separate chromosomes.independent assortment
Hybrid meansHeterozygous
Monohybrid meansHybrid for a single trait (Tt)
Dihybrid means Heterozygous for 2 genes (TtYy)
A cross between two dihybrids is calledDihybrid cross (Tt Yy x Tt Yy)
A cross between two organisms that are each hybrid for a single traitMonohybrid cross (Tt x Tt)
Monohybrid cross produces a phenotypic monohybrid ratio of ___________ in F2 generation. 3:1
Dihybrid cross produces a phenotypic dihybrid ratio of ___________ in F2 generation. 9:3:3:1
Monohybrid cross produces a genotypic ratio of ___________ in F2 generation. 1:2:1
Dihybrid cross produces a genotypic ratio of ___________ in F2 generation. 1:2:1:2:4:2:1:2:1
Test cross ratio for monohybrid versus dihybridMonohybrid !:1 vs Dihybrid 1:1:1:1
___________is a form of intermediate inheritance in which one allele for a specific trait is not completely expressed over its paired allele. This results in a third phenotype in which the expressed physical trait is a combination of the phenotypes of both alleles.Incomplete dominance. For example, a cross between a homozygous white-flowered plant and a homozygous red-flowered plant will produce offspring with pink flowers.
Incomplete dominance is characterized by ___________blending
A form of dominance in which the alleles of a gene pair in a heterozygote are fully expressed thereby resulting in offspring with a phenotype that is neither dominant nor recessive.Codominance. In codominance both traits show
An example of codominanceMN blood groups of humans
Most genes in a population exist in only 2 allelic forms. When there are more than 2 allelic forms of a gene, it is called Multiple alleles. For example, (pea plants; tall or short - T or t) and (3 alleles for human blood type - A, B, and O)
Many characteristics such as skin color, hair color, and height result from a blending of several separate genes that vary along a continuum. They are controlled by several genes and are calledPolygenic inheritance
Two alleles may produce an intermediate phenotype when both are present, rather than one fully determining the phenotype.Incomplete dominance
Two alleles may be simultaneously expressed when both are present, rather than one fully determining the phenotype.Codominance
Genes carried on sex chromosomes, such as the X chromosome of humans, show different inheritance patterns than genes on autosomal (non-sex) chromosomes.Sex-linked genes
Recessive sex-linked traits are ___________ common than the dominant sex-linked traitsmore
Males suffer with sex-linked conditions ___________ than females do.more often
If a sex-linked trait is due to a ___________, a female will express the phenotype only if she carries 2 mutated genes (X-X-). If a female carries only one mutated x-linked gene, she will be a ___________ (X-X). If a male inherits a mutated X-linked gene (X-Y), he ___________ express the gene recessive mutation, carrier, will
Common examples of recessive sex linked traitscolor blindness & hemophilia
Caused by the absence of one or more proteins necessary for normal blood clottingHemophilia
In fruit flies, the expression of the mutation for vestigial wings (short, shriveled) can be altered by temperature which is an example of Environmental effects on the expression of genes
Inheritance can be influenced by the sex of the individual carrying the traits calledSex-influenced inheritance
An example of Sex-influenced inheritanceMale pattern baldness in humans
A laboratory procedure that analyzes size, shape, and number of chromosomesKaryotype
An individual's collection of chromosomes, a laboratory technique that produces an image of an individual's chromosomes, used to look for abnormal numbers or structures of chromosomes.Karyotype
A genetic representation of a family tree that diagrams the inheritance of a trait or disease though several generations and shows the relationships between family members and indicates which individuals express or silently carry the trait in question.Pedigree
Any abnomality in the genome; can occur in somatic cells or in germ cellsMutation
Mutation caused by a change in a DNA sequenceGene mutation
Gene mutation is a change in the nucleotide sequence, in a particular gene, whereas ___________ is a change in several genes, in the chromosome.chromosomal mutation
___________ is a small-scale alteration, but chromosome mutation can be considered as a serious alteration.Gene mutation
Gene mutations can sometimes be ___________, but chromosomal mutations are hardly corrected.corrected
An error that sometimes happens during meiosis in which homologous chromosomes fail to separate as they should.Nondisjunction
Any abnormal chromosome conditionAneuploidy
If a chromosome is presented in triplicate, the condition is known as Trisomy
Having 3, #21 chromosomesTrisomy 21 or Down Syndrome
47 chromosomes with trisomy-21 = an extra chromosome 21Trisomy 21 or Down Syndrome
XXY 47 chromosomes = a male with an extra X chromosome (Normal 44 + 2 = 46)Klinefelter's syndrome
Have male genitals, but the tests are abnormally small and these men are sterileKlinefelter's syndrome
An organism in which the cells have an extra set of chromosomes is referred to as ___________ and an organism with more than 3 sets of chromosomes is referred to as ___________,triploid (3n), polyploid
Chromosomal aberration by a fragment lacking a centromere is lost during cell divisionDeletion
Chromosomal aberration by a chromosomal fragment reattaches to its original chromosome but in reverse orientationInversion
Chromosomal aberration by a fragment of a chromosome becomes attached to a non-homologous chromosomeTranslocation
Chromosomal aberration by having extra sets of chromosomesPolyploidy
Chromosomal aberration happens during meiosis in which homologous chromosomes fail to separate as they should.Nondisjunction
Inability to break down the amino acid phenylalanine and requires elimination of phenylalanine from diet; otherwise serious mental retardation will resultPhenylketonuria/PKU (Autosomal recessive)
The most common lethal genetic disease in the U.S., 1 out of 25 Caucasians is a carrier, and characterized by buildup of extracellular fluid in the lungs, digestive tract, etc.Cystic fibrosis (Autosomal recessive)
Onset is early in life and is caused by lack of the enzyme needed to break down lipids necessary for normal brain function, it is common in Ashkenazi Jews and results in seizures, blindness, and early death.Tay-Sachs disease (Autosomal recessive)
A degenerate disease of the nervous system resulting in certain and early death, onset is usually in middle ageHuntington's Disease (Autosomal dominant)
Caused by the absence of one or more proteins necessary for normal blood clotting.Hemophilia (Sex linked recessive)
Usually involves the inability to distinguish between shades of red and green.Color blindness (Sex linked recessive)