Autosomal Inheritance - Video Tutorials & Practice Problems
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concept
Autosomal Inheritance
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Video transcript
In this video, we're going to begin our lesson on autosomal inheritance. And so what's important to know is that a specific family trait or disorder can be tracked over multiple generations to identify the inheritance pattern. Now moving forward in our course, we're going to talk about 2 main types of inheritance patterns. And so the inheritance patterns can either be autosomal or the inheritance pattern can be sex linked. Now moving forward, we're first going to talk about the autosomal inheritance and autosomal disorders, but then later in our course in different videos we'll talk more about the sex linked disorders and sex linked inheritance. But in our next video we'll talk more about these autosomal disorders and inheritance. So I'll see you all there.
2
concept
Autosomal Disorders
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5m
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Video transcript
In this video, we're going to focus on autosomal disorders. And so traits or disorders that are associated with autosomes, which recall from our previous lesson videos are non sex chromosomes, can be inherited in 2 ways that we have number down below, number 1 and number 2. And so the first way that these autosomal traits or disorders can be inherited is as autosomal dominant disorders. Now autosomal dominant disorders, as their name implies, are going to be disorders associated with autosomes in which individuals with at least one dominant allele will have the disorder. And so for example, the individual could either be homozygous dominant or heterozygous and still have the disorder because they have at least one dominant allele. Now dominant disorders tend to appear in every generation without skipping a generation. Now the second way that autosomal disorders can be inherited is as autosomal recessive disorders. And of course as their name implies autosomal recessive disorders are disorders associated with autosomes in which the individuals that are homozygous recessive are gonna be the ones that display the disorder. And so only individuals that have 2 lowercase letters for their genotype or 2 alleles will actually have the autosomal recessive disorder, which is different than having at least one capital, or one dominant allele to have the disorder. Now autosomal recessive disorders, they tend to skip a generation. And so if we take a look at our image down below, we can further distinguish between autosomal dominant disorders and autosomal recessive disorder pedigrees. And so over here on the left what we have is an autosomal dominant disorder. A disorder that's known as polydactyly which results in having extra digits, either extra fingers or extra toes. And so, because it is an autosomal dominant disorder that means that it's the dominant allele that's associated with the disorder. And so what you can see here is that having a capital f would result in having extra fingers or toes or about polydactyly, which it whereas having the lowercase f would be having the normal number of fingers and toes. And so individuals that have at least one capital f are going to have polydactyly since it is a autosomal dominant disorder. And so notice that all of the ones that are shaded with the blue background are ones that are affected or that actually have polydactyly. And notice that all of them have at least one capital f, which is going to give them polydactyly. And all of the individuals that are not affected are going to be homozygous recessive and have 2 lowercase f's, and so the ones that are not affected are again not shaded. Now over here on the right hand side, what we're showing you is an autosomal recessive disorder, which is specifically cystic fibrosis. And so because, cystic fibrosis is an autosomal recessive disorder, it's actually associated with the lowercase allele, the recessive allele, instead of being associated with the dominant allele. And so, individuals that have a dominant allele are going to be saved from having the disorder. They're gonna be healthy individuals. Whereas individuals that have 2 lowercase a's, individuals that are homozygous recessive, are going to actually have cystic fibrosis. And so that's exactly what we see over here in this pedigree. All of the shaded individuals are individuals that have the disorder cystic fibrosis, And notice that all of them are homozygous recessive. And so, all of the ones that are not affected have at least one dominant allele to save them from having the disorder. Now one thing to note is that autosomal recessive disorders tend to skip an entire generation. And so notice that this generation here in the middle is not being affected, and the disorder seems to skip an entire generation. Whereas with autosomal dominant disorders, it tends to be in every generation. It tend to be present in every generation. And so this here concludes our introduction to autosomal disorders and distinguishing between autosomal dominant disorders and autosomal recessive disorders. And we'll be able to get some practice applying these concepts as we move forward in our course so I'll see you all in our next video.
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Problem
Problem
If a genetic counselor was examining a pedigree chart and noticed an occurrence of a disease in every generation, the counselor would most likely assume that the disease was caused by:
A
A new reoccurring mutation.
B
An autosomal recessive disorder.
C
A chromosomal abnormality.
D
An autosomal dominant disorder.
E
Having an extra set of chromosomes.
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Problem
Problem
The pedigree chart shown depicts the inheritance pattern of __________.
A
An autosomal recessive characteristic with both parents being heterozygous.
B
An autosomal dominant characteristic with both parents being homozygous dominant.
C
An autosomal recessive characteristic with both parents being homozygous recessive.
D
None.
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Problem
Problem
Determine the likely pattern of inheritance in the following pedigree. List the genotypes of the numbered individuals in this order: #1, #2, and #3.
A
aa, aa, aa.
B
Aa, Aa, Aa.
C
Aa, Aa, aa.
D
AA, Aa, aa.
E
None of the above.
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Problem
Problem
The following pedigree is for the ABO blood type group, which is an example of autosomal inheritance. Using the IA, IB, i for the alleles, fill in the top half of each box/circle with the genotype. Also, fill in the bottom half of each box/circle with the phenotype (A, B, AB, or O blood type). If it is impossible to know for certain a specific allele in the genotype, then place a '?' as a placeholder to represent the allele that is in question.