Questions and Answers
What term is used for having two identical alleles?
Homozygous
What term is used for having two different alleles?
Heterozygous
Which genetic disorder results from a recessive gene?
Advancing maternal age decreases the risk of having a child with Down Syndrome.
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Huntington's Disease is a fatal progressive brain disorder where brain cells die, leading to a loss of control over movements and ___________.
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Match the genetic disorder with its description:
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Study Notes
Traits and Genes
- Traits are determined by pairs of genes, each member of a pair is an allele
- Homozygous: having two identical alleles
- Heterozygous: having two different alleles
- Incomplete dominance or codominance: when the effects of both alleles are shown
Dominant and Recessive Traits
- People who bear one dominant gene and one recessive gene for a trait are carriers of the recessive gene
- Recessive genes can cause diseases such as cystic fibrosis and sickle-cell anemia
Chromosomal Abnormalities
- Chromosomal abnormalities can be numerical (e.g. monosomy, trisomy) or structural
- Down syndrome is usually caused by an extra chromosome in the 21st pair, resulting in 47 chromosomes
- Advancing maternal age increases the risk of having a child with down syndrome
- Women between 35 to 39 have the highest percent change at 29%
Sex-Linked Chromosomal Abnormalities
- Abnormalities that are transmitted from generation to generation and are carried on the sex chromosome
- Examples include infertile, maleness and femaleness differences, and numerous disorders stemming from an abnormal number of sex chromosomes
Genetic Abnormalities
- Phenylketonuria (PKU): transmitted by recessive gene, 1 in 12,000 newborns will have PKU
- Huntington's disease: fatal progressive brain disorder, genetic miracle discovered
- Sickle cell anemia: recessive gene, common among black North Americans, neglected disease due to no precise stats
- Cystic fibrosis: recessive gene, most fatal among children and young adults, thick build up of mucus in the lungs, trouble absorbing nutrients
- Sex-linked genetic abnormalities: hemophilia, colour blindness, only carried on the X sex chromosomes, females less likely because they have two X chromosomes
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Description
This quiz covers the basics of genetics, including alleles, homozygous and heterozygous genes, and incomplete dominance or codominance. It also explains what it means to be a carrier of a trait.