Download How is sickle cell disease treated?

Biology 30 December 8, 2014 – Genetics
Crossword – key terms from mitosis and meiosis for homework.
Notes
Incomplete Dominance – Describes situation where neither of the two alleles for the same gene can completely conceal
the presence of the other. Example can occur with flower colour of some species. A cross between a true breeding redflowered plant (R1R1) and a true breeding white-flowered plant (R2R2) produces offspring with pink flowers (R1R2).
Notice that when representing incomplete dominance that the upper and lower case letters are not used.
What is the outcome when the first filial (F1) generation is crossed.
R1
R2
R1
R1R1 (red)
R1R2 (pink)
R2
R1R2 (pink)
R2R2 (white)
1:2:1 ratio is achieved with incomplete dominance versus with complete dominance get 3:1 ratio.
In humans two genetic conditions have the characteristic of incomplete dominance.
Sickle Cell Anemia (See Article) and Hypercholesterlolemia.
Sickle Cell Anemia
Allele for normal hemoglobin HbA and allele for sickle cell hemoglobin is Hbs. Individuals who are homozygous Hbs Hbs
have sickle cell disease. Individual who are heterozygous carry the trait. Carrying the trait is actually advantages
resistant to malaria being heterozygous is better than homozygous.
Co-Dominance
Is a situation where both alleles are fully expressed, a roan horse or cow is an excellent example.
These animals are heterozygous in which both base colour and white are fully expressed. Get a mixture of hair colour.
One allele is expressed in white hair the other in black or brown.
Solving Genetic Problems – Probability and Autosomal Recessive and Autosomal Dominant Disorders
https://www.youtube.com/watch?v=Qcmdb25Rnyo
Sickle Cell Disease
What is sickle cell disease?
Sickle cell disease is a disorder that affects the red blood cells, which use a protein called hemoglobin to transport oxygen from the
lungs to the rest of the body. Normally, red blood cells are round and flexible so they can travel freely through the narrow blood
vessels.
The hemoglobin molecule has two parts: an alpha and a beta. Patients with sickle cell disease have a mutation in a gene on
chromosome 11 that codes for the beta subunit of the hemoglobin protein. As a result, hemoglobin molecules don't form properly,
causing red blood cells to be rigid and have a concave shape (like a sickle used to cut wheat). These irregularly shaped cells get stuck
in the blood vessels and are unable to transport oxygen effectively, causing pain and damage to the organs.
How do people get sickle cell disease?
Sickle cell disease is inherited in an autosomal recessive pattern. This means that a child will not inherit the disease unless both
parents pass down a defective copy of the gene. People who inherit one good copy of the gene and one mutated copy are carriers.
They are clinically normal, but can still pass the defective gene to their children.
What are the symptoms of sickle cell disease?
Sickle cell disease prevents oxygen from reaching the spleen, liver, kidneys, lungs, heart, or other organs, causing a lot of damage.
Without oxygen, the cells that make up these organs die. For example, the spleen is often destroyed in these patients, leading to some
loss of immune function. As a result, these patients often experience frequent infections.
The red blood cells of patients with sickle cell disease don't live as long as healthy red blood cells. So people with this disorder often
have low red blood cell counts (anemia), which is why this disease is commonly referred to as sickle cell anemia.
When sickle-shaped red blood cells get stuck in blood vessels, patients can have episodes of pain called crises. Other symptoms
include delayed growth, strokes, and jaundice (yellowish skin and eyes because of liver damage).
Organ damage and other complications often shorten patients lives by about 30 years.
How is sickle cell disease treated?
Babies and young children with sickle cell disease must take a daily dose of penicillin to prevent potentially deadly infections. Patients
also take folic acid, which helps build new red blood cells.
Doctors advise people with sickle cell disease to get plenty of rest, drink lots of water, and avoid too much physical activity. Blood
transfusions are commonly done to provide a patient with healthy red blood cells.
People with more severe cases of the disease can be treated with a bone marrow transplant. This procedure provides the patient with
healthy blood stem cells from a donor, ideally a sibling.
Interesting facts about sickle cell disease
Unlike normal red blood cells, which can live for 120 days, sickle-shaped cells live only 10 to 20 days.
In the United States, the disease most commonly affects African-Americans. About 1 out of every 500 African-American babies born
in the United States has sickle cell anemia.
Sickle cell disease is most common among people from Africa, India, the Caribbean, the Middle East, and the Mediterranean. The
high prevalence of the defective gene in these regions may be due to the fact that carriers of a mutation in the beta-subunit of
hemoglobin are more resistant to malaria. Malaria is a disease caused by a parasite transmitted by infected mosquitoes. The sometimes
fatal disease, which causes recurring chills and fever, is common in hot climates.
Huntington’s Disease Pedigree – Biology 30 – Autosomal Dominant Disease (1 copy)
Name:
BIOLOGY 30 – ASSIGNMENT #12 Genetics Inheritance
This assignment is due at the start of class on Monday December 15th, 2014. Your answers to the
questions should be on a separate piece of paper and attach this assignment sheet to the front. Answers
need to be in full sentences. Don’t forget to include your name and date, late assignments will not be
accepted for full marks.
Key Terms 13 Marks
Linked Genes
Crossing Over
Chromosome Mapping
Map Unit
Recombinant Types
Parental Type
Recombination Frequency
Sex-Linked Traits
Barr Body
Multiple Alleles
Order of Dominance
Continuous Traits
Polygenic Traits
1. In zucchini, yellow-coloured flesh is recessive to white-coloured flesh. You are a plant breeder and
would like to know if any of the white-fleshed zucchini you have are heterozygous for the yellow-fleshed
allele. How would you determine this? Describe the procedure you would follow.
2. In tomatoes, red fruit (R) is dominant to yellow fruit (r), and tall (T) is dominant to short (t). Truebreeding tall plants that produced red fruit were crossed with true-breeding short ants that produced
yellow fruit.
a) State the genotype and phenotype of the F1 generation plants.
b) List the genotypes of the gametes produced by the F1 plants.
c) List the genotypes and phenotypes of the F2 generation plants. Include the genotypic and phenotypic
ratios of the F2 generation plants.
3. In mice, black fur (B) is dominant to brown fur (b), and non-waltzer mice (N) are dominant to waltzers
(n). Two mice that are heterozygous for both traits are crossed. Draw a Punnett square for the F1
generation and determine the phenotype ratio for these offspring.
4. The gene that codes for colour in snapdragons, exhibits incomplete dominance. A true breeding red
snapdragon is crossed with a true breeding white snapdragon. What is the phenotype ratio of the F1
generation. The F1 offspring are then crossed to produce F2 generation. Draw a Punnett square for this
generation and determine the phenotypic ratio.
5. Two blue roan horses are bred together, what it the chance that the colt will be white?