Chromosome pairs | Inheritance and variation | Middle school biology | Khan Academy

TL;DR

Chromosomes contain genes that affect an organism's traits, and humans have fewer chromosomes than black mulberry plants and Guinea pigs.

Transcript

• [Instructor] - Hi, everyone. Today, we're gonna talk about chromosome pairs. But first, I've got a question for you. Between a black mulberry plant, a Guinea pig, and a human being, which organism do you think has the most chromosomes? The mulberry plant has green leaves and delicious berries. The Guinea pigs are adorable, tiny mammals with multi... Read More

Key Insights

• ❓ Chromosomes contain genes that affect an organism's traits.
• 💠 Homologous chromosomes have the same size and shape and may have the same or different alleles for a gene.
• 🕵️ A karyotype can be used to detect genetic conditions by examining chromosome size differences or the presence of extra chromosomes.
• 🖤 Black mulberry plants have the most chromosomes, followed by Guinea pigs and humans.

Questions & Answers

Q: What are chromosomes and how do they affect an organism's traits?

Chromosomes are structures that contain an organism's genes, which are units of heredity passed down from parent to offspring. Genes on chromosomes affect an organism's traits, such as physical characteristics or behavior.

Q: What are homologous chromosomes and how do they differ from each other?

Homologous chromosomes are paired chromosomes that have the same size, shape, and genes in the same locations. However, the homologous chromosomes may have the same allele or different alleles for a gene, resulting in variations of a trait.

Q: How can a karyotype be used to identify genetic conditions?

A karyotype is an organized image of an individual's chromosomes. Scientists and medical professionals can examine the karyotype under a microscope to look for size differences between chromosomes within each homologous pair or the presence of an extra chromosome, which may indicate a genetic condition.

Q: Which organism has the most chromosomes among black mulberry plants, Guinea pigs, and humans?

Black mulberry plants have the most chromosomes, with 308 chromosomes. Guinea pigs come in second with 64 chromosomes, and humans have 46 chromosomes.

Summary & Key Takeaways

• Chromosomes are structures that contain an organism's genes, which are passed down from parent to offspring and affect an organism's traits.

• Many species, including humans, have chromosomes that come in matched pairs called homologous chromosomes.

• Different alleles or variations of genes on homologous chromosomes can cause different versions of a trait in an organism.