Unit 4 - Genetics Flashcards
Explain how Klinefelter’s syndrome is caused and what it is. What are the odds of this disorder?
An extra X chromosome in a male (XXY) occurs in 500/1000 births. The male’s testes are abnormally small and the male is sterile. Breast enlargement and other female characteristics can occur. Submornal intelligence is also common. An extra Y (XYY) occurs in 1/1000 males. These males have normal sexual development but tend to be taller than average.
What is aneuploidy?
When a cell has an abnormal amount of chromosomes. Missing or extra chromosomes lead to genetic disorders.
Explain what occurs when a female has triplo-X otherwise known as trisomy X.
It occur in 1/1000 births. The females are taller than average and sometimes have learning disabilities and are infertile.
(XXX)
Explain the concept of autosomal dominance. Give an example.
If a disease is autosomal dominant, one must only receive the gene from one parent in order to inherit the disease. Examples may include Huntington disease, myotonic dystrophy, or Marfan syndrome
What is neurofibromatosis? Is it autosomal dominant or recessive?
NF is a genetic disease in which one develops soft tumors (neurofibromas) under the skin and throughout the nervous system. NF1 is caused by a defect on chromosome 17 while NF2 is cause by a defect on chromosome 22. It is autosomal dominant however it one can also develop the disorder through spontaneous mutation which can also be passed on to offspring.
What is Huntington’s disease? At what age does it have a phenotypic effect?
It is a degenerative disease of the nervous system caused by a dominant allele. Once the deterioration of the nervous system begins it is irreversible. The disease most often takes place between 35-45 years old.
Explain the concept of autosomal recessive. Give an example.
Two copies of an abnormal gene must be present in order for the disease or trait to develop. Examples can include cystic fibrosis, sickle cell anaemia, and PKU.
What is sickle cell anemia?
A recessively inherited blood disorder caused by a nucleotide change in the beta-globin gene. This causes the hemoglobin to aggregate thus changing red blood cell shape.
What is cystic fibrosis?
An autosomal recessive disorder that causes excessive secretion of mucus. This can lead to a body being more vulnerable to infection.
What causes Tay Sachs? What are the symptoms?
Disease caused by a recessive allele for a dysfunctional enzyme. The accumulation of lipids in the brain can lead to seizures, blindness, degeneration of motor and mental skills.
What is PKU (Phenylketonuria)?
A disease in which a recessive allele for an enzyme that disrupts metabolism of an amino acid (phenylalanine) and leads to brain damage.
Explain what is meant by monosomic.
When a diploid cell has one copy of a chromosome instead of the regular two.
Explain what is meant by trisomic.
This occurs when a diploid cell has three copies of of a particular chromosome instead of two.
Explain what is meant by polypoidy.
A mutation in which one has more than two complete chromosome sets due to a mistake in cell division,
Explain Marfan syndrome. Sate what type of dominance the disease is.
Marfan syndrome is autosomal dominant. It is a disorder of connective tissue associated with abnormally long and thin digits. It can also cause optical and cardiovascular defects.
What is the function of DNA polymerase?
DNA polymerase is an enzyme essential to DNA replication, during which it adds corresponding nucleotides to a single strand of DNA.
How does DNA replication differ in eukaryotes and prokaryotes?
In eukaryotes, DNA replication occurs in the nucleus and at multiple locations on a stand of DNA called replication forks. In prokaryotes, DNA replication occurs in the cytoplasm and there is a single origin of replication.
What gives DNA the structure of a double helix?
Hydrogen bonds between base pairs form two antiparallel, bound strands that exist in a spiral.
