Chapter 9 Flashcards
During gamete formation, an egg or a sperm cell gets only one allele for a trait, since eggs and sperm are haploid. The allele passed on is randomly chosen. This called the Law of _________________.,
Segregation
An individual who has one dominant allele for a trait and one recessive allele for that trait is said to be ____________for that trait.
heterozygous
PP could indicate which of the following?
homozygous dominant for purple flowers
An individual who has two dominant alleles for a trait is said to be _____________ for that trait.
homozygous dominant
pp could indicate
homozygous recessive for white flowers
Pp could indicate which of the following
heterozygous dominant for purple flowers
An individual who has two recessive alleles for a trait is said to be _____________ for that trait.
homozygous recessive
One parent plant is homozygous dominant or true breeding purple.
What is the genotype for this parent plant?
PP, Homozygous dominant
One parent plant has two recessive alleles (true breeding white).
What is the genoytope for this parent plant?
pp, Homozygous recessive
What is the phenotype of all the F1 offspring? (What is the phenotype of the PP x pp cross?)
purple
Choose ALL the possible alleles that a homozygous purple plant could contribute to its gametes.P, p, P, p
P, P
T/F If two of the offspring from the PP x pp test cross were to mate, there is a 25% chance of producing white flowers.
TRUE
In regard to genotype, which of the following are TRUE about the offspring of a PP x pp cross?
They are all heterozygous
They are all Pp
They are all purple
They are all heterozygous.
they are all Pp
The genotype of the offpring in percent is _________PP (PP x Pp)
25%
The percent of offpsring with a heterozygous would be (PP x Pp)
50%
The percent of offpsring with a homozygous recessive genotype would be (PP xPp)
25%
What is the chance (in percent) of having a male offspring? (XX and XY)
50%
What is the chance (in percent) of having a female offspring? (XX and XY)
50%
What is genotype?
genetic data (Homogous vs. Heterozygous, Dominant vs Recessive
What is Phenotype?
Phycial representations of genes (hair/eye color)
Indicate the phenotype of the YYRR parent plant.
Domainates are green and wrinkled
Recessives are yellow and smooth
Yellow and smooth
Indicate the phenotype of the yyrr plant.
Domainates are green and wrinkled
Recessives are yellow and smooth
Yellow & smooth
Which of the following are possible gametes for the yyrr plant?
yy, rr, Yr, Yr
YR, YR, yr, yr
yr, yr, yr, yr
yr, yr, yr, yr
Which of the following are possible gametes for the YYRR plant?
YR, YR, YY, RR
YR, YR, YR, YR
YY, RR, YR, YR
YR, YR, YR, YR
Tonya can roll her togue (Tt) and has a straight hairline (hh)
Which is TRUE about Tonya’s genotype?
Tonya is Tt
Tonya is hh
Tonya is homozygous for straight hairline
Tonya can roll her tongue
Tonya is Tthh
Tonya has a widow’s peak
Tonya is Tt
Tonyo is hh
Tonya is homozygous for straight hairline
Tonya is Tthh
Tony can roll his tongue (Tt) and has a widow peak (Hh)
Which of the following would be the correct gametes for Tony?.
TH, Th, tH, th
Tt. TH, Hh, Th
TH, TH, Th, ThTT, HH, tt, hh
TH, Th, tH, th
Tonya can roll her togue (Tt) and has a straight hairline (hh)
Tonya’s possible gametes would be
TH, Th, tH, th
TT, hh, Th, th
Th, Th, th, th
Th, Th, th, th
When crossed with a chocolate lab, which black lab genotype yielded all black puppies (dominant)?
BB
Bb
the lab parent with black fur
BB
Y/N If a chocolate lab parent has a litter of puppies with a homozygous dominant black lab parent, is there a possibility of having any chocolate lab grand-puppies?
No
Some forms of deafness are recessive. Which of the following genotypes would be deaf pheontypically?
DD
dd
Dd
dd
If you wanted to trace a trait through a families history, you would perfom a
pedigree
How many alleles for the disorder must the offspring receive in order to express the recessive disorder?
2
What is the chance that the offspring will NOT show cystic fibrosis (recessive) phenotypically?
75%
What is the chance of having an offspring with cystic fibrosis (recessive)?
25%
What are the chances the child will NOT receiving a recessive disorder gene from either parent?
25%
If a heterozygous person for Huntington’s disease (dominant) crosses with someone without the Huntington’s gene, what is the percent chance their offspring will have the disease?
50%
If a heterozygous person for Huntington’s disease (dominant) crosses with someone without the Huntington’s gene, what is the percent chance their offspring will not have the disease?
50%
If an allele shows incomplete dominance, what will occur phenotypically when it pairs with a recessive allele?
An in-between phenotype will result
What was the genotype for the F1 hybrids? (RR= red rr=white)
heterozygous
What was the phenotype for the F1 hybrids? (RR= red rr=white)
all pink
The genotypic ratio of the F2 generation (RR(red) + rr(white) = all pink)
1 homozygous dominant: 2 heterozygous: 1 homozygous recessive
The phenotypic ratio of the F2 generation is (RR(red) + rr(white) = all pink)
1 red: 2 pink: 1 white
Match the items.
a. Genotype BB or Bo
b. Genotype oo
c. Genotype - AA or Ao
d. Genotype AB
1. Phenotype A blood
2. Phenotype B blood
3. Phenotype AB blood
4. Phenotype O blood
1=c (Phenotype a= Genotype AA or AO)
2=a (Phenotype b= Genotype BB or Bo)
3=d (Phenotype AB= Genotype AB)
4=b (Phenotype O= Genotype oo)
T/F It is possible for ALL four blood type to result from these two parents. (Ao and Bo)
TRUE
A mother who is type A blood has two children, one is type A and one is type O. Her husband is type AB, is he the father of both children?
No
Which three are examples of pleiotropy?
sickle cell anemia
cystic fibrosis
albinism
skin color
eye color
sickle cell anemia
cystic fibrosis
albinism
Which three are examples of polygenetic inheritance?
skin color
sicke cell anemia
hair color
eye color
achondroplasia
Skin Color
hair color
eye color
Are most sex linked genes found on the X or the Y chromosome?
X
In order for a female child to inherit a sex linked disorder, from how many parents must they inherit the recessive alleles?
2
In order for a male child to inherit a sex-linked disorder, who must pass down the recessive sex-linked allele?
mom
Are sex-linked disorders caused by dominant alleles or recessive alleles?
Recessive
Which of the following is an example of incomplete dominance in humans?
flower color
freckles
hairline
earlobe attachment
skin color
Skin color.
If for each gene there are two alleles but there are more than two possible alleles in the wider population we call this:
Multiple alleles
T/F? Genetics as well as the environment affect characteristics.
TRUE
T/F Genes on the same chromosome are inherited separately.
FALSE
Perform a dihybrid cross of the following and then choose the correct phenotypic ratio. Purple flowered tall plants (PPTT) x white flowered dwarf plants (pptt).
1:0:0:0
f your crossed two pink snap dragons which of the following is the correct result?
25% Red, 25% White, 50% Pink
The alternative versions of a gene are called
Alleles
What does HH denote?
Homozygous Dominant
A ‘true-breeding’ plant is a variety that when self-fertilized, an offspring is produced that is identical to one another and to the parent.
TRUE
Which of the following choices best describes a discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA?
Chromosome
Trait
DNA
Gene
Allele
Gene
Both Mr. and Mrs. Smith are carriers for deafness. What are the chances of their offspring being deaf?
25%
T/F With incomplete dominance the offspring will have an intermediate phenotype.
TRUE
What does hh denote?
Homozygous recessive
AB blood type in humans is an example of
Co-dominance
T/F The breast cancer genes, BRCA 1 anad BRCA 2 are not detectible using genetic testing
FALSE
AB blood type in humans is an example of
Codominance
If for every gene you have two alleles, one you inherited from each parent, which of the following laws explains how sperm and egg carries only one allele for each trait? And that at fertilization each contributes its allele restoring the normal paired allele to the offspring.
Law of Segregation
T/F? Sex linked disorders affect males and females equally.
FALSE
T/F A ‘true-breeding’ plant is a variety that when self-fertilized, an offspring is produced that is identical to one another and to the parent.
TRUE
What does Hh denote?
Heterozygous
If you crossed a true breeding red snap dragon with a true breeding white snap dragon what percent of the offspring would be pink?
100%
T/F For each characteristic, an organism inherits two alleles, one from each parent.
TRUE
The hybrid offspring of true -breeding parental plants is called the
P generation
F1 generation
F2 generation
H generation
F1 Generation
An organism who inherits two different alleles for a gene is said to be _________ for that gene.
Heterzygous
T/F The Blending Hypothesis stated that traits mix together like paint and can not be separated. This explains how traits that disappear in one generation can reappear in later ones
FALSE
Define genetics
Discrete heriable factors
define true breeding
PP + pp
What are mendels 4 hypotheses
1.) Alleles are alt forms of genes
2.) 2 alleles for each characteristics, 1 from each parent
3.) when 2 alleles of a pair are diff, 1 is fuly expressed (Pp)
4.) law of segregation: alleles separate from eachother in meiosis
What is meant by dominant and recessive alleles
Dom: expressed (D)
Recss: not expressed unless homozygous recessive (d)
Define Homozygous
2 identical alleles (DD)
Define heterzygous
2 diff alleles (Dd)
What is genotype? Phenotype?
Geno: genetic makeup
Pheno: physical expression
What 3 combos can a pair of allels be found
Homo Dom: DD
Homo Recessive:dd
Hetero: Dd
What is a dihybrid cross
mating parents w 2 characteristics
Identify gametes of TtYy
TY, Ty, tY, ty
What is meant by the principle of independent assortment
alleles f genes are distributed to gametes randomly, genes are inherited independently from eachother, random orientation on metaphase plate in meta 1
What is a carrier? how can 2 hearing parents have a deaf child
Carrier: Popele who carry one copy of the allele for a recessive disorder (Dd)
If both parents are carriers they have a 25% chance of having a deaf child
When are recesisve disorders expressed?
Homozygous recessive for the trait
what are examples of recessive disorders?
Deafness, Cistic fibrosis, albanism, tay-sachs, sickle cell
What is a dominant disorder? Why are they less common?
Disorders carried in dom alleles. Only happens if heterozygous
What are examples of dominant disorders?
Achroplasia (dwarfism), Alzheimers, huntingtons
Describe incomplete dominance
Inbtw pheontype where one allele is not completly expresed over the other (not the same as blending)
Define and give examples of polygenetic inheritance
2+ genes control one pehnotype trait
Ex: Skin color, height, weight, eyecolor, herat disease
Explain pleitropy and give an example
One gene controls multiple charcateristics
Ex: Sickle cell
Define sex-linked traits. give some examples
Gene located on either sex chrom (usually X)
Ex: Red/Green colorblindness, Hemophilia, dachenae-muscular dystrophy
Who was the father of genetics?
Gregor Mendel
What did mendel study?
Variation among garden pea plants.
What was Mendel’s 4 Principles?
1) Each individual has at least two alleles for each trair, one from each parent.
2) The different versions of a trait are contained by the two inhereted alleles. (Homo or hetero)
3) Expression of trait physically is determined by the genetic information from both parents. An individual contains one allele from one parent, and one allele from the other.
4) The alleles may be dominant or recessive.
Which type of allele is expressed?
Dominant
What is an allele?
A different version of a gene
What does locus mean?
Location of genes on chromosomes.
What does genotype mean?
Genetic makeup of individual. Allele makeup (Hh, HH, hh)
What does phenotype mean?
The trait that is shown, actual physical makeup.
What is a monohybrid cross?
Crossing one character. Two alleles on a single locus are studied.
What does homozygous dominant mean?
It means both alleles are dominant. Both capitalized letters.
What does heterozygous dominant mean?
It means that you have one dominant allele and one recessive. One uppercase, one lowercase letter.
What does homozygous recessive mean?
It means that both alleles are recessive. Both lowercase letters.
What does true breeding mean?
It means that both parents only have 1 type of allele. (HH and hh)
If a parent plant is homozygous dominant, or true breeding purple, and the other is homozygous recessive, or true breeding white, what would the genotype look like?
0% PP, 100% Pp, 0% pp
What is a punnett square?
A grid of boxes used to determine all possible outcomes of alleles from genetic crossing.
What is the P generation?
The parental generation.
What is the F1 generation?
The offspring produced from crossing of 2 parents.
Given the previous example, what is the F1 generation genotype?
25% PP, 50% Pp, 25% pp
Given the previous example, what is the F1 generation phenotype?
75% purple, 25% white
You do a monohybrid cross of a male (XY) and a female (XX) and get XX, XX, XY, and XY. What percent of offspring will be male? Female?
50% and 50%
What is a dihybrid cross?
A two trait test cross to determine the genotype for two traits.
YY = yellow seeds. Yy = yellow seeds. yy = green seeds. RR = smooth seeds. Rr = smooth seeds. rr = wrinkledseeds. What would the PHENOTYPE be for YYRR and Yyrr?
YYRR = Yellow and smooth. Yyrr = yellow and wrinkled.
What method do you use to set up a dihybrid cross?
FOIL method.
Tongue rollers (T) can roll the edges of their tongue up to form a U shape. The inability to roll one’s tongue is recessive (t). Both Tony and his wife Tonya are heterozygous for tongue rolling. A widow’s peak hairline (H) is dominant over a straight hairline (h). Tony is hererozygous for a widow’s peak, but Tonya has a straight hairline. What are their GENOTYPES?
Tony: TtHh
Tonya: Tthh
Tony’s genotype is TtHh. Tonya’s genotype is Tthh. What are their possible gametes?
Tony: TH, Th, tH, th.
Tonya: Th, Th, th, th
What is a test cross?
It is performed to determine the genptypes of two parents. It is working backwards to use the offspring phenotype to determine the genotypes of the parents.
Give an example of a test cross.
Black fur is the dominant color in labrador retrievers, so a black lab could have either genotype Bb or BB. Chocolate labs are recessive, so all chocolate labs must be bb. If you have black and chocolate puppies, you would have had to cross a bb (chocolate lab) with a Bb (black lab).
What are recessive disorders?
They are disorders located on autosomal chromsomes. People with these are often born to normal parents.
If a parent is ____ for a disorder, then they are a carrier.
Hererozygous
How many alleles for the disorder must the offspring receive in order to express the recessive disorder?
2, homozygous recessive.
Recessive disorders include:
Cystic fibrosis, Albinism, Tay-Sachs, and Sickle Cell Anemia. (CATS)
Most disorders are autosomal recessive. What does that mean? Would the carrier likely show the signs of the disorder?
It means that the disorder shows up on a heterozygous recessive offspring. Carrier wouldn’t show signs of it, but it means that their parents were carriers also.
Define pedigree. When might a pedigree be useful?
Pedigree is a chart that diagrams inheritance of health conditions. It can be used to see if parents are carriers.
What is a dominant disorder?
When the dominant allele causes the disorder to express phenotypically. Offspring will exhibit the disorder if only one allele is inherited.
Dominant recessive disorders include:
Huntington’s, Alzheimers, Achondroplasia, and Polydactylism.
Why are dominant disorders less common than recessive disorders?
Because if they are homozygous, the embryo dies before it can even be born.
What is incomplete dominance?
When the dominant allele(s) are not fully dominant and a small percent of the recessive allele expresses phenotypically.
If an allele shows incomplete dominance, what will occur phenotypically when it pairs with a recessive allele?
You will see a mixture of both dominant and recessive.
What is a common example for incomplete dominance?
Snapdragons. RR is a homozygous dominant red, and rr is homozygous recessive. The offspring will all be pink.
How do you know genes aren’t ‘blended’ together?
Because the heterozygote contains both distinct alleles in their phenotype.
What is codominance?
When there is more than one dominant allele.
What is a common example of codominance?
Blood type in humans.
What are the 4 possible phenotypes for blood type?
A, B, AB, or O
What is the genotype for A?
AA or AO.
What is the genotype for B?
BB or BO.
What is the genotype for AB?
AB
What is the genotype for O?
OO
What blood type is the universal donor?
O blood
What blood type is the universal recipient?
AB
How are incomplete dominance and co-dominance different?
In incomplete dominance, there is expression from both the dominant and recessive alleles, so the offspring doesn’t display characteristics of its parents. In co-dominance, offspring exhibits both traits simotaniously.
What is pleitropy and an example?
It is when one gene controls multiple characteristics. Ex) Sickle cell disease (homozygous recessive)
What is polygenetic inheritance?
When many genes affect a single phenotype. Ex) eye color, skin color, hair type. (A, B, C alleles are incompletely dominant over a, b, c alleles).
How are skin color and eye color examples of polygenetic inheritance?
Because they are controlled by many genes that are incompletely dominant. There is a spectrum/gradient of the phenotype.
How are phenotypes a combination of genetics and environment?
Because someone can have the genetic makeup for a phenotype, but the environment can cause it to be something else. For example, someone could have the genetic makeup for a high IQ, but if they never are exposed to learning, then that environment causes them to remain with a low IQ.
What are sex linked traits?
They are genes located on either sex chromosome.
What is another name for sex linked traits?
X-linked
Why are sex linked disorders more common in men than women?
Because males only have 1 copy of the X chromosome, whereas women have 2 copies. Males only need one defective allele to be affected.
Are sex-linked disorders caused by dominant alleles or recessive alleles?
Recessive alleles. (XC = dominant and normal. Xc = recessive and defective).
Define genetics, hybrids, and true breeding.
Genetics is the study of heredity. Passing of characteristics or traits to offspring. Hybrids are an organism that have 2 different alleles for a trait. True breeding is when an organism has both the same allele for a trait
What are Mendel’s 4 hypothesis?
1) Each individual has at least two alleles for each trair, one from each parent.
2) The different versions of a trait are contained by the two inhereted alleles. (Homo or hetero)
3) Expression of trait physically is determined by the genetic information from both parents. An individual contains one allele from one parent, and one allele from the other.
4) The alleles may be dominant or recessive.
What is meant by dominant and recessive alleles?
Dominant is what is expressed, recessive is the other trait.
Define homozygous, heterozygous, P generation, F1 generation, F2 generation.
Homo: both alleles same. Hetero: one of each allele. P generation: parental generation. F1: offsprings made from breeding the parent generation. F2: offspring made from breeding the F1 generation.
What is meant by genotype? Phenotype?
Genotype is the possible genetic makeup, and phenotype is what is actually expressed.
In what three combinations can a pair of alleles be found?
Homozygous dominant, homozygous recessive, and heterozygous.
What is a dihybrid cross?
When you cross 2 different characters on different genes.
What is meant by the principle of independent assortment?
Genes for different traits can segregate independently during the formation of gametes
When is making a pedigree beneficial?
When you are trying to see if a parent is a carrier.
Describe a carrier. How can two parents with normal hearing produce a deaf child?
When a parent is heterozygous. They don’t express it, but they carry the allele for it.
When are recesisve disorders expressed? Give some examples.
When you have a homozygous recessive offspring. An example is Cystic fibrosis, albinism, tay-sachs, and sickle cell anemia.
Define dominant disorder. Why are they less common than recessive disorders? Give some examples.
It is when the dominant allele causes the disorder to express in the phenotype. They are less common because if you have a homozygous dominant offspring, they die right away. Examples are Huntington’s, alzheimers, achondroplasia, and polydactylism.
Describe incomplete dominance
When the dominant trait doesn’t fully mask the recessive trait so both show up phenotypically.
Define and give examples of polygenetic inheritance
Polygenetic inheritence is when multiple genes code for one characteristic, like hair color or eye color.
Explain the inheritance of blood type. What are the posisble combos?
It is co-dominant. This means both dominant alleles are expressed.
Explain pleitropy and give an example
It is when a single gene controls multiple characteristics. An example is sickle cell.
List some benefits of genetic testing. Disscuss the dangers of genetic tesing
You will be able to tell if you are a carrier. It can be emotionally and socially dangerous.
Define sex-linked traits. give some examples
Sex linked traits are ones that are located on either sex chromosome. Examples are color blindness and hemophilia.
