The recessive sickle-cell allele is maintained in the...

Name: Problem 11, Chapter 15: Essentials of Biology
Uploaded: 2021-03-15T19:40:45-08:00
Duration: 6 min 28 s
Channel: Danielle Ashley
Description: The recessive sickle-cell allele is maintained in the populations in regions where malaria is prevalent because a. the allele confers resistance to the parasite. b. gene flow is high in those regions. c. disruptive selection is occurring. d. genetic drift randomly selects for the allele.

The recessive sickle-cell allele is maintained in the populations in regions where malaria is prevalent because a. the allele confers resistance to the parasite. b. gene flow is high in those regions. c. disruptive selection is occurring. d. genetic drift randomly selects for the allele.

The recessive sickle-cell allele is maintained in the populations in regions where malaria is prevalent because
a. the allele confers resistance to the parasite.
b. gene flow is high in those regions.
c. disruptive selection is occurring.
d. genetic drift randomly selects for the allele.

Key Concepts

Heterozygote Advantage

This concept refers to the phenomenon in which individuals carrying two different alleles for a gene (heterozygotes) have a higher fitness than those with two copies of either allele. In regions where malaria is prevalent, those with one normal allele and one sickle-cell allele gain partial resistance to malaria while avoiding the full-blown effects of sickle-cell disease, which illustrates this advantage.

Balancing Selection

Balancing selection is a natural selection process that maintains multiple alleles in a population. It occurs when heterozygous individuals have a selective advantage, as seen in the case of the sickle-cell allele in malaria-endemic areas, thereby preserving both the normal and the sickle-cell alleles in the gene pool.

Transcript

00:01 Today we are going to be answering a question in regards to a chapter on evolution on a small scale.

00:08 So the statement reads, the recessive sickle cell allele is maintained in the populations and regions where malaria is prevalent.

00:23 Because why? why is that? is it because the allele confers resistance to the parasite or is gene, or is the gene flow is high in those regions, or disruptive selection is occurring or genetic drift randomly selects for the alleles? you can pause a video and decide which one you believe is the correct answer.

00:54 And we'll come back to discuss more about the question.

01:00 Okay, so about sickle cell anemia or disease.

01:07 It's basically caused by a mutation in the gene that tells your body to make the iron -rich components that makes blood red and enables red blood cells to carry oxygen from your lungs throughout the body.

01:28 Throughout your body or hemoglobin.

01:34 But in sickle cell anemia, the abnormal hemoglobin caused red blood cells to become rigid, sticky, and misshapen, which makes it harder for the blood to basically carry oxygen and all that.

01:50 And with these type of scenario, it usually affects people who are african who are african or of african descent.

02:00 And in these type of scenarios, really probably seeing how they found it interesting that even with this abnormality, they're really surprised that people who have sickle cell, they tend to live in population where malaria is very high and prevalent.

02:24 And they're wondering why is so.

02:26 And we have our options and we'll just go over a couple like with genetic drift.

02:35 Genetic drift just basically refers to changes in the allele's frequency of the gene pool due to chance.

02:44 And that wouldn't count because it's just basically it's by chance where that would happen.

02:54 So we are not going to say, we're not going to sit here and say that that's really the case.

03:02 Disrupted selection, that's not really the case because it takes two or more extreme phenotypes that are favored over the intermediate in seeing that even though, yeah, the sickle cell alleles, since they said they were recessive, it wouldn't count.

03:24 And let's check on with gene flow.

03:28 And gene flow is basically the movement of alleles among population by migration of breeding individuals...

Please give Ace some feedback