Question 1

Gene expression refers to the

Accepted Answer

Gene expression refers to the process by which genetic information is used by a cell to create a specific functional product, such as a protein. This process involves the conversion of genetic instructions, encoded in DNA, into a functional feature of a living cell.

Question 2

Brandon and Jacob are identical twins. However, Brandon had a finger damaged in an accident, so even if you couldn't tell them apart from a distance, once you saw the finger you knew who was who. This difference is a characteristic of their

Accepted Answer

Phenotypes are the observable physical or biochemical characteristics of an organism, which can result from both genetic and environmental factors. In this case, the damaged finger is a visible physical difference between the two twins, making it a phenotype. Genotypes refer to the genetic makeup of an organism, while personalities are behavioral and psychological traits that are not directly related to physical appearance. Heterozygous chromosomes refer to the presence of two different alleles (versions) of a gene on a pair of chromosomes.

Question 3

You were recently introduced to your roommate's sibling. To your surprise, even though the siblings are the same sex, they look nothing alike. Which of the following is the best explanation of this situation?

Accepted Answer

While siblings do share genes, there are many different possible combinations of genes that can result from a single parent's contribution. It is possible that the two siblings do not share many alleles due to random assortment during reproduction.

Question 4

The passing along of genes that are physically close to one another on the same chromosome is known as

Accepted Answer

The passing along of genes that are physically close to one another on the same chromosome is known as linkage.

Question 5

Which of the following accurately describes the attraction of bases between strands of DNA?

Accepted Answer

A pairs with T (adenine with thymine) and C pairs with G (cytosine with guanine) through hydrogen bonding, which is fundamental to the structure of DNA.

Question 6

Which of the following is the best definition of a gene?

Accepted Answer

A gene is a hereditary unit made of DNA that occupies a fixed location on a chromosome. It contains the instructions for producing a specific protein or RNA molecule. Genes are the molecular units of heredity and determine a variety of traits and characteristics in an organism.

Question 7

The _____ is a group of three consecutive bases in a gene that codes for one amino acid in a protein.

Accepted Answer

The three consecutive bases in a gene that codes for one amino acid in a protein is called a codon. The other options are not related to this concept. The proteome refers to all the proteins expressed by an organism or cell. Tripheme is not a commonly used term in genetics or biology. Ribosome is a cellular structure responsible for protein synthesis but is not specifically related to a group of three bases in a gene.

Question 8

During meiosis, the process where chromosomes exchange equivalent sections of genetic material is called

Accepted Answer

Crossing over is the process during meiosis in which homologous chromosomes exchange equivalent sections of genetic material. This creates genetic diversity among gametes. Choices A, C, and D are not accurate descriptions of this process.

Question 9

Alternative versions of a particular gene are known as

Accepted Answer

Alternative versions of a gene are called alleles. A single gene can have multiple alleles that differ in their nucleotide sequence, resulting in different forms of the gene. SNPs are a type of DNA variation that involves a single nucleotide change within a gene or non-coding DNA region. Imprinted genes are genes that are expressed in a parent-of-origin-specific manner, meaning that the expression of the gene is influenced by whether it was inherited from the mother or the father. Proteomes refer to the complete set of proteins that are expressed by an organism or a cell.

Question 10

Cystic fibrosis is a fatal lung condition that results from a recessive gene. If one parent is a healthy carrier for the condition while the other is not a carrier, what is the likely outcome for any children they might have?

Accepted Answer

If one parent is a carrier and the other is not, each child has a 50% chance of inheriting the cystic fibrosis gene from the carrier parent. If a child does not inherit the gene, they will not have the disease and will not be a carrier. However, if they do inherit the gene, they will not have the disease, but they will be a carrier. Therefore, none of the children will have the disease, but each child has a 50% chance of being a carrier.

Question 11

Huntington's disease, a fatal degenerative movement disorder, results from large numbers of codon repeats in the Huntingtin gene located on chromosome 4. This means that the

Accepted Answer

The extra codon repeats in the Huntington gene will result in the production of a protein with abnormally large amounts of the amino acid encoded by the extra codons. This abnormal protein accumulation leads to the degenerative movement disorder characteristic of Huntington's disease. A is incorrect because extra codon repeats do have an impact on the individual's phenotype. B is incorrect because the affected gene still produces a protein, albeit an abnormal one. D is incorrect because the extra codons result in more of the encoded amino acid, not less.

Question 12

Javier and Alyssa are brother and sister, and both have O type blood. They know that their mother has type A blood, but do not know their father's blood type. Given this information, what could their father's blood type be?

Accepted Answer

Javier and Alyssa have O type blood, which means they must have received an O allele from each parent. Their mother, with type A blood, could be genotype AO, providing an O allele. Therefore, their father could have blood type A (genotype AO), B (genotype BO), or O (genotype OO) to provide the second O allele.

Question 13

An allele that produces a phenotypical trait regardless of whether or not its pair is homozygous or heterozygous is

Accepted Answer

A dominant allele will produce a phenotypical trait regardless of whether its pair is homozygous or heterozygous. In contrast, a recessive allele will only produce a phenotypical trait when both pairs are homozygous for the recessive allele. Imprinting refers to differential expression of alleles based on whether they were inherited from the mother or father, and an SNP (single nucleotide polymorphism) is a genetic variation that occurs when a single nucleotide in a DNA sequence is altered.

Question 14

Sarah's mother has Huntington's disease, an illness that results from a dominant gene. Her father, on the other hand, does not have the illness. What is the likelihood that Sarah herself will develop the disease?

Accepted Answer

Huntington's disease is caused by a dominant gene, meaning that if a person has one copy of the disease gene, they will develop the disease. Sarah's mother has the disease, so she must have at least one copy of the disease gene. However, since her father does not have the disease, he must have two copies of the healthy gene. So Sarah could inherit either a healthy allele from her father or an allele that produces the illness from her mother, giving her a 50 percent chance of developing the disease.

Question 15

In which of the following cells would you NOT find the same deoxyribonucleic acid (DNA) as any of the other trillions of cells in your body?

Accepted Answer

Red blood cells do not have a nucleus or DNA, so they cannot contain the same DNA as other cells in the body. Other cells like leukocytes, white blood cells, and basophils all have a nucleus and therefore contain DNA.

Question 16

Nancy and Cliff had four children who did not have cystic fibrosis, but their fifth child was born with the disease. Cystic fibrosis is carried on a recessive gene. Given what you've learned in this chapter, how could this happen?

Accepted Answer

In order for a child to inherit a recessive genetic disorder like cystic fibrosis, both parents must carry a copy of the mutated gene. If the parents are carriers, each of their children has a 25% chance of inheriting two copies of the mutated gene and thus having the disorder. It is possible for multiple children in a family to not have the disorder if they inherit the normal gene from both parents, but for the fifth child to have the disorder, both parents must have passed on the recessive gene to that child.

Question 17

In cases of partial dominance, a heterozygous offspring of two homozygous parents will

Accepted Answer

In cases of partial dominance, the heterozygous offspring will have an intermediate phenotype that is a blend of both homozygous parents. This is because neither allele is completely dominant or recessive, resulting in an intermediate phenotype.

Question 18

A single human can produce eggs or sperm with more than _________ different combinations of his or her chromosomes.

Accepted Answer

A human can produce eggs or sperm with 8,000,000 different combinations of his or her chromosomes. This is because during meiosis, the chromosomes can undergo crossing-over and independent assortment, leading to a large number of possible combinations.

Question 19

When either a mother's or father's version of a gene is expressed in a cell, but not both, we refer to the gene as

Accepted Answer

When a gene is imprinted, it means that only one allele (either the maternal or paternal version) is expressed in a cell, while the other allele is silenced. This is due to epigenetic modifications to the DNA, such as DNA methylation, that determine which allele is expressed. Dominant and recessive genes refer to the way in which alleles interact with each other to determine a trait, while SNP (single nucleotide polymorphism) refers to a variation in a single nucleotide in the DNA sequence.

Question 20

The _____ is the set of all protein encoded and expressed by the genome of an organism.

Accepted Answer

The term "proteome" refers to the complete set of proteins that can be expressed by the genome of an organism. This includes all of the different types of proteins that are produced at different times and in different tissues or cell types. The other answer choices are not correct:

- B) "Tripheme" is not a biological term or term used to describe any aspect of genetics or genomics 
- C) "Ribosome" is a cellular organelle that is involved in protein synthesis, but it does not refer to the complete set of proteins expressed by the genome 
- D) "Codon" refers to a sequence of three nucleotides in DNA or RNA that codes for a specific amino acid, but it does not refer to the complete set of proteins expressed by the genome.

Quiz 5: Genetics and the Development of the Human Brain