Unlike genetics, which focuses on single genes, genomics studies all of a person's genes and how they interact with each other and with the environment.
Missing Word
genomics
Genomics looks at the whole set of genes and their interactions with one another and with environmental factors. It helps explain complex diseases such as heart disease, diabetes and cancer.
Category: Genetics and Genomics
Question 2
Down syndrome usually results from nondisjunction, the failure of paired chromosomes to separate properly when an egg or sperm is formed.
Missing Word
nondisjunction
Nondisjunction is an error in which chromosomes fail to separate during cell division, leaving a gamete with an extra or missing chromosome. It is the most common cause of Down syndrome and becomes more likely as maternal age rises.
Category: Chromosomal Conditions
Question 3
A person who inherits two different alleles of a gene, one from each parent, is heterozygous for that gene.
Missing Word
heterozygous
Heterozygous means having two different versions of a gene. A person who is heterozygous for a recessive disorder is usually an unaffected carrier.
Category: Inheritance Patterns
Question 4
When both alleles are fully expressed at the same time, as when the A and B blood group alleles together produce type AB blood, the pattern is called codominance.
Missing Word
codominance
In codominance, neither allele masks the other and both appear in the phenotype. The A and B alleles of the ABO system are codominant, while the O allele is recessive.
Category: Inheritance Patterns
Question 5
A laboratory image of a person's chromosomes arranged in matched pairs by size and shape is a karyotype.
Missing Word
karyotype
A karyotype displays the paired chromosomes so that abnormalities in number or structure, such as an extra or missing chromosome, can be seen.
Category: Chromosomal Conditions
Question 6
The chromosome pairs that are not sex chromosomes are called autosomes.
Missing Word
autosomes
Autosomes are all the chromosome pairs other than the sex chromosomes. Disorders carried on them, such as cystic fibrosis and Huntington disease, affect males and females alike.
Category: Chromosomal Conditions
Question 7
To work out whether a disorder in a family follows a dominant, recessive or X-linked pattern, the nurse charts the relatives and shades those who are affected on a pedigree.
Missing Word
pedigree
A pedigree is a diagram of a family's health history drawn with standard symbols across several generations, with affected relatives shaded. Its pattern helps show how a disorder is inherited and which relatives may be at risk, and every nurse is expected to be able to build one from a family history.
Category: Family History and Risk
Question 8
The observable traits that result from a person's genes interacting with the environment make up the phenotype.
Missing Word
phenotype
The phenotype is what can be seen or measured, such as blood type or the presence of a disease. It reflects both the genes a person carries and environmental influences.
Category: Genetics and Genomics
Question 9
A person's genetic makeup for a particular trait, such as having one dominant and one recessive allele, is that person's genotype.
Missing Word
genotype
The genotype is the specific combination of alleles a person carries for a gene. Two people with the same visible trait can have different genotypes, such as a homozygous dominant person and a carrier.
Category: Genetics and Genomics
Question 10
Prader-Willi syndrome often results from a deletion, the loss of a segment of a chromosome.
Missing Word
deletion
A deletion removes genetic material. When a large segment of a chromosome is lost, as in Prader-Willi syndrome, many genes are missing and multiple body systems can be affected.
Category: Mutations
Question 11
Meiosis is the cell division that halves the chromosome number to form eggs and sperm.
Missing Word
Meiosis
Meiosis produces gametes with a single set of chromosomes. Errors during this division can leave an egg or sperm with the wrong number of chromosomes and are thought to cause many miscarriages.
Category: Chromosomal Conditions
Question 12
Mendel's law of segregation states that each parent passes only one of its two copies of a gene to each offspring.
Missing Word
segregation
The law of segregation says that the paired copies of a gene separate when gametes form, so each offspring receives one copy from each parent.
Category: Inheritance Patterns
Question 13
Because a child inherits these energy-producing organelles only from the egg, disorders of the mitochondria are passed on through the mother.
Missing Word
mitochondria
Mitochondria carry their own DNA and are inherited only from the mother. Both sons and daughters can be affected by mitochondrial disorders, but only mothers transmit them.
Category: Inheritance Patterns
Question 14
An autosomal dominant disorder that causes tumors to grow along nerves, along with skin and skeletal changes, is neurofibromatosis.
Missing Word
neurofibromatosis
Neurofibromatosis is an autosomal dominant condition, so a single copy of the altered gene from one parent is enough to cause it. It causes nervous system tumors and skin and skeletal abnormalities.
Category: Inheritance Patterns
Question 15
In the DNA double helix, adenine always pairs with thymine.
Missing Word
thymine
In DNA, adenine pairs with thymine and cytosine pairs with guanine, which allows each strand to serve as a template for copying.
Category: Genetics and Genomics