Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
21 Cards in this Set
- Front
- Back
Recessive inherited disorders (cause)
|
Phenotype is caused by the inheritance of two recessive alleles
|
|
Recessive inherited disorders must have...
|
homozygous recessive alleles
- allele codes for malfunctional protein or no protein at all |
|
Recessive inherited disorders (examples)
|
I. Cystic Fibrosis
- Lethal - Disease of mucus secreting glands II. Tay Sacks - Lethal - Lacks enzyme which metabolizes lipids in the brain III. Sickle Cell anemia - single amino acid substitution - red blood cells deform in shape IV. Albinism |
|
Dominantly inherited disorders are... (result)
|
expressed even if only one allele is affected
|
|
Dominantly inherited disorders (example)
|
Huntington's disease
- degenerative disease of the nervous system - onset of disease at 40-50 years old |
|
Sex is determined by... (chromosomes)
|
sex chromosomes, X and Y
|
|
Each gamete has one... (chromosome)
|
sex chromosome
|
|
Chances of producing a male or female
|
50/50
|
|
Males receive their X chromosome from...
|
their mothers
|
|
Females receive their X chromosomes from...
|
each parent
|
|
Female have... (number of X chromosomes)
|
two X chromosomes
- alleles can be either homozygous or heterozygous |
|
Recessive allele (in females, what happens?)
|
The trait is only expressed if she is homozygous
e.g. X(G) X(g) -> carrier X(g) X(g) -> expresses the trait |
|
Recessive allele (in males, what happens?)
|
The trait is expressed
e.g. X(g) Y -> expressed |
|
Autosomal recessive (define)
|
The trait is on one of the 44 autosomes
|
|
Sex linked recessive (define)
|
They are found on one of the two sex chromosomes, the X
|
|
Fathers pass their X genes to...
|
all their daughters only
|
|
Mothers pass their X genes to...
|
both sons and daughters
|
|
Recessive sex linked disorders are predominantly...
|
male
|
|
Sex linked disorders (examples)
|
I. Colour blindness
II. Hemophilia - lacks one of many clotting factors - gene is found on the X chromosome - similar inheritance pattern as for colour blindness III. Duchenne Dystrophy |
|
X-inactivation (define)
|
In females, only one X-chromosome is active
- Embryonic cells inactivate one of the two X chromosomes - Condenses into a dense object: barr body (genes are inactive) |
|
Process of X-inactivation
|
Lyon hypothesis
- Inactivation occurs randomly in embryonic cells - Patches of tissue have only one active X-chromosome |