Genes, Alleles, and Traits: Unraveling Genetic Diversity in Biology

This video continues the discussion on DNA, focusing on genetic terms such as alleles, dominant and recessive traits, homozygous and heterozygous conditions, and the concepts of genotype and phenotype. It explains how genes, as segments of DNA, code for proteins and determine traits. The video also covers how alleles represent different versions of a gene, and how dominant alleles are expressed over recessive ones. The differences between genotype (the genetic makeup) and phenotype (the observable traits) are highlighted, using examples of mice with different fur colors. The video concludes with a preview of the next topic: genetic diagrams.

What is an allele?

• A different version of the same gene

• A dominant trait

• A segment of DNA that codes for a protein

• A type of protein

Which of the following is true about genes?

• They are always responsible for a single trait

• They code for proteins that determine traits

• They are identical in every individual

• They do not interact with each other

Which of the following is an example of a trait determined by a single gene?

• Height

• Fur color in mice

• Intelligence

• Skin color

What does it mean if an organism is homozygous for a trait?

• It has two different alleles for a gene

• It has two identical alleles for a gene

• It has no alleles for a gene

• It has a dominant and a recessive allele

In a heterozygous organism, which allele is expressed?

• The recessive allele

• Both alleles equally

• The dominant allele

• Neither allele

What is the phenotype of a mouse with one purple and one green fur allele, if purple is dominant?

• Neither color

• Green

• A mix of purple and green

• Purple

Which of the following best describes a recessive allele?

• An allele that is never expressed

• An allele that codes for a dominant trait

• An allele that is expressed only when two copies are present

• An allele that is always expressed

What does genotype refer to?

• The physical appearance of an organism

• The recessive traits only

• The entire collection of alleles in an organism

• The dominant traits only

How can two organisms have the same phenotype but different genotypes?

• They have no alleles in common

• They cannot have the same phenotype

• They have different alleles but the same dominant trait is expressed

• They have identical alleles

What determines the phenotype of an organism?

• Only the dominant alleles

• The genotype and environmental factors

• Only the recessive alleles

• The number of genes