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48 Cards in this Set

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How do monozygotic twins compare genetically?
Monozygotic twinsare derived from one sperm and one egg and, therefore, are 100% geneticallyidentical.
True orfalse: All of the genes in each cell in the body are active and produceproteins.
False. Althougheach cell contains the same genes, some of these genes are expressed whileothers are not.
Name thesteps of the human life cycle
• The zygote eventually becomes the fetus.

• Cell differentiation produces the various structures of the human body.


• Billions of cells are eventually produced, each having the same genetic information.


• Sperm and egg join through the process of fertilization.

If several specific traits exist in an individual, which situation would increase the number of genetically unique gametes produced?
Many of the alleles for the traits are on different chromosomes. If the alleles are on different chromosomes, they will assort independently during gamete formation.
Which cell would contain a single copy of each of the human body's 23 chromosomes?
sperm cell. Sperm cells are haploid, so they have only one chromosome of each homologous pair.
Which processes increase genetic diversity?
• segregation

• random fertilization


• crossing over


• Mutation

Which process does not increase genetic diversity?
Cell differentiation occurs after meiosis and fertilization, so it does not change the genetic makeup of an individual.
True or false: Human cells contain more genetic information than the cells of any other organism.
False. Some nonhuman organisms have cells that contain many more chromosomes than human cells do.
How do these embryo’s compare genetically?
• 100 % genetically identical for monozygotic twins

• 50 % genetically identical for dizygotic twins

Why might a dysfunctional gene affect one type of cell in the body, but not other types of cells?
•Cells express only the genes required for their particular activities.

• Cells only use the genes they need for their particular function; for example, only eye cells express rhodopsin.

After a human egg and sperm fuse in fertilization, what is the immediate result?
• A zygote is the result of fused gametes.
How do dizygotic twins compare genetically?
• Dizygotic twins are derived from two different sperm and two different eggs and thus are genetically no more similar than siblings born at different times.
What does homozygous dominant look like?
• DD
What does heterozygous dominant look like?
• Dd
What does homozygous recessive look like?
• dd
In a pea plant, yellow seeds are dominant and green seeds are recessive. A pea plant that is homozygous dominant for seed color is crossed with a pea plant that is heterozygous. What color seeds are possible in the offspring?
Because the cross would yield only homozygous dominant and heterozygous offspring, all offspring would have the dominant phenotype: yellow seeds.
Two carriers of the cystic fibrosis gene conceive a child. What is the probability that their child would have cystic fibrosis?
In a cross between two heterozygotes, 25% of offspring are likely to have the disease.
A woman with one allele for Huntington's disease marries a man who also has one allele for the disease. What is the probability that their child will have the disease?
Since this disease is caused by a dominant allele, a child that inherits even one allele will get the disease. In a cross between two heterozygotes, there is a 75% probability that a child will receive at least one allele for Huntington's disease.
Which expression directly represents a genotype?
• FFGg
Name three quantative traits in humans?
• height, weight and blood pressure.
For the trait of weight, which population is likely to have the most variability?
• an auditorium of parents

• A random selection of parents is likely to show high variability in weight.

In a flock of chickens, the heritability of egg weight is found to be 0.35. What conclusions can be made about this data?
• Heritability measures the effect of genes on the variability of a quantitative trait in a population. A heritability of 0.35 means that genetics accounts for 35% of the variation in egg weight among the chickens, whereas 65% of the variation is due to environmental factors.
How is the phenotype of a quantitative trait expressed?
• Quantitative traits show continuous variation, which means that there is a large range of phenotypes in a population
If the heritability of intelligence in a population of mice is 0.95, what does this tell us?
• Heritability measures the genetic influence on a trait; 0.95 heritability of intelligence means that 95% of the variation in intelligence in this mouse population is attributable to genetics.
What is one difference between calculating heritability of traits in cattle and heritability of traits in human populations?
• Manipulating human environments and reproduction is not practical or ethical.• To calculate heritability in human populations, researchers must perform correlations among individuals who have varying degrees of genetic similarity.
To which group are measures of heritability applied?
• Heritability is a measure of the proportion of variation of a quantitative trait in a particular population that is due to genetics.
How is codominance expressed?
• Both alleles are expressed in the phenotype of the heterozygote.• In codominance, neither allele is dominant to the other, so both are expressed.
What pattern of inheritance produces offspring with orange flowers from a cross between a plant with yellow flowers and a plant with red flowers?
• Incomplete dominance produces a phenotype in the heterozygote that is in between that of the two homozygotes.
The offspring of a horse with a black coat and a horse with a white coat is a horse with patches of black and white in its coat. What pattern of inheritance for coat color is found in these horses?
• codominance.

• Both alleles are equally expressed for the codominant trait in the heterozygote.

What are the blood types?
• IA is the blood type A allele

• IB is the blood type B allele


• i is the blood type O allele.


• IA and IB are codominant, while i is recessive

Jim has type B blood. Christa has type O blood. Josh and Kevin have type B blood. Pradeep has type AB blood. What possibilities exist for blood donations between these people?
• Josh, Kevin, and Jim could be blood donors to Pradeep.

• Because Pradeep has type AB blood, his blood would not create antibodies to any blood type

If an Rh– mother has an Rh+ baby, what are the possible genotypes of the baby's father?
• Rh+/Rh+ or Rh+/Rh–

• The father could be homozygous dominant or heterozygous to have an Rh+ baby with an Rh– mother

How do incomplete dominance and codominance compare?
• In codominance, the heterozygote expresses both phenotypes; in incomplete dominance, the heterozygote shows an intermediate phenotype.
A breeder of Cochin chickens breeds a group of white-feathered hens with a black-feathered rooster. The resulting chicks all develop gray feathers. If feather color is controlled by a single pair of genes, what genetic phenomenon is occurring?
• The black and white alleles are incompletely dominant.
What sex chromosome would you get from your father?
• Y from dad

• X from mom

What pair of chromosomes found in a human cell determine the gender of the individual?
• A human body cell has one pair of sex chromosomes and 22 pairs of autosomes (nonsex chromosomes).
A woman has a disorder, and her husband does not. The disorder is inherited by all of their male offspring, but none of their female offspring. Their children marry spouses who are normal. When their daughters have children, half of their sons and none of their daughters have the disorder. When their sons have children, none of their children inherit the disorder. What mode of inheritance does this disorder follow?
• sex-linked recessive.
What type of chromosomes found in human cells comprise 22 pairs and do not determine the gender of the individual?
• Autosomes are the non-sex chromosomes; each human cell contains 22 pairs of autosomes and 2 sex chromosomes.
What type of genetic disorder would show mostly males being affected on a pedigree diagram?
• X-linked recessive diseases often show up in males, because they only need one copy of the allele for the disease to be affected.
The root meta- means what?
change or between
The root meio- means what?
to make smaller
The root mito-means what?
a thread
The root onco- means what?
cancer.
The root proto- means what?
prior to or before
The root soma- (or -some) means what?
a body
The root telo- means what?
the end or completion.
Meiosis is the division of the nucleus that occurs in where?
sex cells
Telophase is the final stage of what?
mitosis.