Chapter 12 Review (May need to look at review for some answers) – Flashcards
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Is the trait being studied in the bedigree recessive or dominant? How do you know?
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None of the babies have it, because they are not shaded. Not everyone shows the trait
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Are II-1 carriers of the trait? How do you know?
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They had to be carriers otherwise the kids wouldn't have the trait
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What is the probability that II-1 and II-2 will produce an individual with the trait beign studied?
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25% or 1/4
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What is the likely genotype of II-4 for the trait being studied in the pedigree?
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Big H little h
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Tay-Sachs disease
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Recessive disorder that results from the absence of an enzyme required to break lipids down
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Huntington's disease
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Lethal genetic disorder caused by a dominant allele
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Cystic Fibrosis
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Most common genetic disorder among white Americans
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Phenylketonuria
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Recessive disorder that results from the absence of an enzymes that converts one amino acid into another one
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Simple dominant traits
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widow's peak, and hitch hiker's thumb
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Traits controlled by more than two alleles are said to have multiple alleles
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True
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Multiple alleles can be studied only in individuals
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false; pigeons
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In humans, there are 23 pairs of matching homologous chromosomes called autosomes
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False; 22, 1 is just a second chromosome (23rd is a sex chromosome)
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Two chromosomes called the sex chromosomes determine the sex of an individual.
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true
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The sex chromosomes of a human male are XX, and the sex chromosomes of a human female are XY
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False, Male XY, Female XX
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Traits controlled by genes located on sex chromosomes are called sex-linked traits
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true
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The first known example of sex-linked inheritance was discovered in pea plants
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false
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What characteristic of an organism can affect gene function?
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The genetic makeup of an organism at fertilization determines only the organism's potential to develop and function
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Do the internal environments of males and females differ? Explain.
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Yes, because of their hormones and structural differences.
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What are some environmental factors that can influence gene expression?
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Temperature, nutrition, light, chemicals, infectious agents, age, and gender/ sex
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Give two examples of how an environmental factor can affect the expression of a phenotype.
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1) horn size in mountain sheep is expressed differently between males and females...
2) Patter of baldness in humans appears in the male sex/gender
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Is it possible to infer from the pedigree whether or not I-1 and I-2 are carriers of the allele? Explain.
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Yes, they had a kid and grandkids that have the trait
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What can be inferred about the genotype of II-5 based on the person's descendants?
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His grandkids have it
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Is II-1 a carrier of the recessive allele? Explain.
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No, their kids don't have it, there mom has it and the kids don't have it, II-1 is not a carrier.
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Are II-3 and II-4 carriers of the recessive gene? Explain.
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There's a 2/3 chance they may have it but you may not know until they do have kids
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Why must III-4 and III-7 be heterozygous
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Their kids have it
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Can you infer from the pedigree whether the pattern of inheritance is autosomal or sex-linked?
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autosomal because two male and a female have it...
autosomal, male/female have it...
sex-linked is either only male, or only female
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Phenotypes of both homozygotes are produced in the heterozygote
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codominant alleles
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Phenotypes of both heterozygous and homozygous dominant individuals have the same phenotype
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completely dominant alles
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the phenotype of the heterozygote is intermediate between those of phenotypes expressed by the homozygotes
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incomplete dominance
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another name for a heterozygous individual
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carrier
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inheritance pattern of phenylktonuria and tay-sachs disease
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simple recessive heredity
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inheritance pattern of a trait controlled by two or more genes
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polygenic inheritance
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a graphic representation of an individual's family tree
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pedigree
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humans have 22 pairs of these types of chromosomes
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autosomes
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traits controlled by genes located on the X or Y chromosomes
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sex-linked traits
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The 23rd pair of chromosomes that differn in males and females are called
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sex chromosomes
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a trait controlled by four alleles is said to have
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multiple alleles
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When roan cattle are mated, 25% of the offspring are red, 50% are roan, and 25% are white. Upon examination, it can be seen that the coat of a roan cow consists of both red and white hairs. This trait is one controlled by
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codominant alleles
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if a female fruit fly heterozygous for red eyes (X^R,X^r) crossed with a white-eyed male (X^r,Y), what percent of their offspring will have white eyes
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50%
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What is the relationship between individual I-1 and individual III-2?
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grandmother-grandson
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For the trait being followed in the pedigree, individuals II-1 and II-4 can be classified as
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carriers
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What type of inheritance pattern does this trait represented by the shaded symbols illustrate?
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sex-linked
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If individual III-2 marries a person with the same genotype as individual I-1, what is the chance of that one of their children will be afflicted with hemophilia?
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0%
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Because the gene for red-green colorblindness is located on the x chromosome, it is normally *not* possible for a
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colorblind father to pass the gene to his son
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A cross between a white rooster and a black hen results in a 100% blue Andalusian offspring. When two of these blue offspring are mated, the probable phenotypic ratio seen in their offspring would be
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25% black, 50% blue, 25% white
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A human genetic disorder caused by a dominant gene is
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Huntington's disease
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How does polygenic inheritance differ from Mendelian inheritance?
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Mendelian inheritance only account for one gene affecting a trait. For example, there is only one gene that determines if a pea plant's flower will be white or purple.
On the other hand, polygenic inheritance refers to more than one gene affecting a trait. For example, there are dozens of individual traits in your DNA that collectively determine your hair color.
Polygenic inheritance explains why there are thousands of natural shades of hair color.
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How does incomplete dominance differ from multiple alleles?
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*Incomplete dominance,* heterozygous individuals don't appear dominant but instead they appear intermediate between the two homozygotes...
*Multiple alleles,* more than two alleles, pigeons for example, have three alleles of one gene govern feather color, each pigeon only inherits two
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Write the one that does *not* belong in the list then explain.
()heterozygous, carrier, homozygous
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homozygous because carrier and heterozygous are the same thing
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Write the one that does *not* belong in the list then explain.
()genotype, phenotype, heterozygous, homozygous
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phenotype doesn't belong
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Write the one that does *not* belong in the list then explain.
()autosomes, X and Y chromosomes, sex-linked traits
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autosomes: x and y chromosomes are sex-linked
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Explain how some traits are expressed differently in males and females. Give an example of such a trait.
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males determine the sex of an offspring, females- hormones, females have more breast tissue
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The gene for nearsightedness in humans is found on the X chromosome. A boy has a nearsighted father. Will the boy be nearsighted? Explain.
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no, y chromosome comes from father
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A male is said to be hemizygous for genes on the X chromosome. Explain why you think this term was chosen.
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half is x chromosome half is y chromosome
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How might the disappearance of the trait of miniature wings be explained?
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The trait was recessive, but the kids are carriers.
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What does this tell you about the trait for miniature wings?
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It's a recessive trait
