Genetic Disorders
What is a carrier?
Someone who has one copy of a recessive allele but does not show symptoms
What is a DNA profile used for?
Identifying relationships or individuals (paternity tests, ancestry tests, forensics)
What percentage chance does a child have of being a carrier if both parents are carriers?
50%
What is artificial insemination?
Placing sperm into a woman’s uterus without intercourse.
What is a carcinogen?
A substance or agent that is known to cause cancer.
True or False: Down syndrome results from having an extra chromosome
True
What is cloning?
Creating an exact genetic copy of a cell or organism.
If both parents are heterozygous for a dominant disorder, what is the chance their child will be unaffected?
25%
What are the basic steps of in vitro fertilization?
Collect eggs → collect sperm → fertilize in petri dish → implant embryo into uterus.
How does the growth rate of cancer cells compare to that of normal cells?
Cancer cells grow much faster than normal cells.
Which genetic disorder causes thick mucus to build up in lungs and digestive organs?
Cystic fibrosis
In gene therapy, what is inserted into a patient’s cells?
A normal (healthy) copy of the gene causing the disorder.
What is the chance two carriers of a recessive disorder have a child who is completely unaffected?
25%
In reproductive cloning, what happens to the nucleus of the donor egg?
It is removed and replaced with a nucleus from a somatic (body) cell.
Name 3 carcinogens.
Ultraviolet (UV) light, second-hand smoke, smokeless tobacco, X-rays, certain chemicals, etc.
Explain why a person with the genotype "OY" cannot survive
Y chromosome alone cannot support life; no essential genes from X chromosome
Describe two examples of how genetic engineering is used in medicine or agriculture.
Insulin production in bacteria, pest-resistant crops, fast-growing salmon, goats producing clotting proteins, etc.
What is the phenotype of a person who is heterozygous for a dominant disorder?
They are affected, because dominant alleles show even if only one copy is present.
Describe one key difference between artificial insemination and in vitro fertilization (IVF)
In artificial insemination, sperm is inserted directly into the uterus to fertilize the egg naturally inside the body, while IVF fertilizes the egg outside the body before implanting the embryo into the uterus.
Explain how mutations in genes controlling the cell cycle can lead to cancer.
Mutations to genes that control the cell cycle could allow cells to divide uncontrollably without normal regulation, forming tumors.
Explain how nondisjunction during meiosis can lead to a genetic disorder like Down syndrome.
Nondisjunction is when chromosomes fail to separate properly during meiosis. This results in gametes with an extra chromosome. If a gamete with an extra chromosome 21 fuses with a normal gamete, the resulting zygote has three copies of chromosome 21, causing Down syndrome (trisomy 21).
Compare and contrast cloning and genetic engineering.
Cloning creates a genetically identical copy of an organism without changing the DNA sequence, while genetic engineering involves altering an organism's DNA to give it new traits. Cloning copies entire genomes; genetic engineering changes specific genes.
If two carriers of a recessive disorder have children, what are the possible genotypes and phenotypes of their offspring?
Genotypes: 25% affected, 50% carriers, 25% unaffected
Phenotypes: affected, carrier, unaffected.
Describe the full process used to create Dolly the sheep, including the steps involving the donor cell, egg cell, and surrogate.
Nucleus removed from donor egg cell.
Body (somatic) cell from donor sheep fused with the egg.
Fused cell developed into an embryo.
Embryo implanted into surrogate mother.
Surrogate gave birth to Dolly, genetically identical to donor sheep.
Explain how cancer spreads
Cancer spreads when cells from a tumor break away and travel through the bloodstream to other parts of the body. These cells can invade and grow in new tissues, forming secondary tumors. This process is called metastasis.