Amoeba Sisters Video Recap- DNA, Chromosomes, Genes, and Traits: An Intro to Heredity

ANSWER KEY The vocab below builds a foundation for understanding heredity! Complete the table using your own words and creativity.

Name Illustrate! Explain it in Your Own Words

What’s its Significance? (Why does it matter?)

Real Life Example

DNA 1. Illustrations mayvary! Ours is below.

2. Genetic materialarranged in a double helixshape which can code fortraits.

3. DNA is an organism’sgenetic code! It can code fortraits that an organism has.Without a genetic code, anorganism would not exist.

DNA found in the body cell of a snake

Chromosome 4. Illustrations mayvary! Ours is below.

5. Compacted units ofDNA and protein. AnswerKey Note: The video doesnot mention specific typesof proteins involved inchromosomalorganization.

Chromosomes allow the large amount of DNA to be compacted. One reason this is significant is in cell division as it makes it much easier for the cells to put these units into the new cells.

6. A chromosome in a human. Humans have 46 found in most body cells.

Gene 7. Illustrations mayvary! Ours is below. Asmentioned in video,genes are typicallymade of more basesthan able to be shown.

8. Made up of portions ofDNA with the ability tocode for proteins whichcan be involved inexpressing a trait.

9. Genes can code forproteins, which can beinvolved in expressing traits.The proteins they code forcan also be involved intransport, structure, in actingas enzymes that make allkinds of materials, protectingthe body, and more!

One of many genes that can code for a protein involved in eye pigment

Trait 10. Illustrations mayvary! Ours is below.

11. A characteristic thatan organism has. AnswerKey Note: You may wishto discuss that not alltraits are externallyvisible. Blood type, forexample, is a trait.

12. Traits are thecharacteristics thatorganisms have, and manycan be important forsurvival. Example: a snake’scolor pattern that helps itblend in with itsenvironment.

13. Human eye color

14. For the diagram at right, please label the following words on thediagram.(A) Deoxyribose (sugar), (B) Phosphate, and (C) Nitrogenous Base.Answer Key Note: Labeled at right.15. Based on the definition, how many nucleotides do you see in this diagram? _6_16. What are the four different types of bases in DNA and how do they pair?Adenine (A), Thymine (T), Cytosine (C), and Guanine (G). Adenine pairs with Thymine.Cytosine pairs with Guanine.

17. When studying heredity, what is the relationship of DNA bases and traits?The sequence of the DNA bases can actually code for traits.

(B)

Phosphate

(A) Deoxyribose (sugar)

(C) Nitrogenous Base

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Amoeba Sisters Video Recap- DNA, Chromosomes, Genes, and Traits: An Intro to Heredity

ANSWER KEY

A Picture Says It! 18. Explain what this image represents regarding where your entire DNAcode can be found.In eukaryotes, the entire DNA code can be found in [nearly] all of thebody cells, which is what this image shows.[Answer Key Note: The video mentions that genes are regulated. Itmay be helpful to emphasize that despite having the full DNA code,not all genes may be “turned on” in a cell. For example, a stomachcell may have genes activated that are involved in producing stomachacid. Skin cells may have those genes “turned off” in gene regulation]

19. Apply Your UnderstandingSpike is not a clone of his father. He inherited DNA from both of his parents.Chromosomes are condensed units of DNA. If Spike has 36 chromosomes, you wouldexpect that Spike would have inherited __18__ chromosomes from his mother and__18___ chromosomes from his father.

20. How did you determine the chromosome numbers and how does that relate to heredity?

Offspring receive half of their chromosomes from each parent. Since Spike has 36 chromosomes, he received ½ of that (18) from his mother and ½ of that (18) from his father. Heredity involves the passing of traits down from parent to offspring. DNA can code for those traits, and that DNA is condensed into chromosomes that the offspring inherits from its parents.

21. As mentioned in the video, the environment can also affect an organism’straits. The example of nourishment was used in the case for Spike, as this couldaffect his growth and size. This can also occur in humans. UV light was notmentioned in the video. How could UV light potentially affect an organism’s trait?Provide one example.

Examples may vary, especially since the question allows it to be anyorganism. Here are a few examples:-UV light can affect the size of plants, since plants require light for growth.-UV light can affect human skin color as pigmentation can change with UV light exposure.-UV light exposure can be involved in vitamin D synthesis in some organisms, and a severe deficiency could affectbone density (and more).

22. Recap the VocabIdentify some of the vocabulary you worked withby labeling them on this illustration:

DNA Gene – NOTE: Green portion of DNA. As mentioned in video, genes are typically made of more bases than able to be shown. Chromosome Nucleotide Phosphate Deoxyribose (sugar) Nitrogenous Base

DNA Gene

Phosphate

Deoxyribose (sugar)

Nitrogenous Base

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Amoeba Sisters Video Recap: Alleles and Genes ANSWER KEY

1. Visualizing the Vocabulary: For the following illustration,determine where you could label the following terms:allele, gene locus, and chromosome. Be sure to drawarrows to specify where you are labeling!

Analyzing Inheritance: A human’s DNA code, found in nearly all body cells, can be condensed into chromosomes.

2. How many chromosomes do humans have total in each*body cell? ____46______

3. How many of those chromosomes in each human *bodycell are from the mother? ___23_______

4. How many of those chromosomes in each human *bodycell are from their father? ___23_______

5. How many pairs of chromosomes are there in eachhuman *body cell? ___23_______

6. When looking at each pair, how many chromosomes ineach pair come from the mother? __1__ Father? __1__

*some exceptions

7. Working with the Vocabulary: In your own words, explain how a person may taste the bitterness of PTC by using thefollowing vocabulary words in your explanation (choose any order): trait, gene, genotype, phenotype, and alleles.Underline each word as you use it in your explanation. In this explanation, you can treat PTC taste sensitivity as a single-gene trait. [As mentioned in the video, it may be more complex than a single-gene trait.]

Assuming a single gene trait [if PTC tasting is not considered to be influenced by more than 1 gene], then a person that has a gene that codes for the trait of tasting PTC will be able to taste PTC. Humans inherit two alleles, or forms of a gene, as they receive one allele from each parent. Therefore a person who tastes PTC inherited at least one dominant allele (dominant form of the gene) which allows for the PTC tasting trait as tasting PTC is a dominant trait. If using “T” to represent this dominant allele, then this person’s genotype would have to contain at least one “T” allele. Either of those genotypes would code for the physical characteristic of tasting PTC, which is a “PTC taster” phenotype.

Allele

(Note:

Could be

same or

different

from other

allele)

Gene

Locus

Allele

(Note:

Could be

same or

different

from other

allele)

Chromosome Chromosome

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Answer Key Note: Students will be assessed in their

understanding of ‘gene’ vs ‘allele’ in the last question on

handout as the labeling will not reveal a difference between

these two yet. A gene is typically used to describe area on

DNA that codes for a trait (ex: PTC taste sensitivity gene).

Since chromosomes are made of DNA and protein, you can

specify an area of a chromosome as containing a gene.

Alleles are forms of that gene and specify different varieties

(ex: being able to taste, not being able to taste). See last

question.

Amoeba Sisters Video Recap: Alleles and Genes ANSWER KEY 8. Deducing a Genotype: If assuming PTC as a simple gene trait,what other genotype would you select to put in this missinggenotype box that could result in this phenotype? Why?

Assuming PTC as a simple gene trait, the other genotype would be Tt, because PTC tasting is a dominant trait. This means that a genotype that results in the PTC tasting phenotype must contain at least one dominant “T” allele. The only other combination is “tt” and this would be a non-taster.

[Answer Key Note: Some students may think that the combination Tt is different from tT. You may wish to explain that the order does not make a different trait, but when writing genotypes, the dominant allele is placed first.]

9. Relevant Scenario: When explaining dominant andrecessive traits to a younger family member, they respond,“Well chances are I can probably taste PTC, since dominanttraits are more common.” How might you address thismisconception?

Dominant traits are not always more common. While a dominant trait only needs one dominant allele to be expressed (assuming Mendelian inheritance), it is possible the dominant allele itself is more rare. If the dominant allele is more rare, the dominant trait may not be as common in a population. The video gives the example of polydactyl, as some forms of polydactyl can be a dominant trait.

10. Contrast: Many times, students struggle with the difference between the terms allele and gene. How would you explain the difference of these two terms in a way that is memorable to you?

A gene is typically defined as a general area on DNA that can code for a specific trait. This can also be an area on a chromosome, because a chromosome is composed of DNA and protein. So, in the example from this video, a gene could be an area on a chromosome that codes for PTC taste sensitivity. An allele is a variant of the gene. In the simplified example, an allele could be for tasting PTC or not tasting PTC. Therefore, the term ‘gene’ is used when referring to a general area that can code for a trait and the term ‘allele’ is used when referring to the actual form of that gene as there can be variants. As humans, we inherit one allele from each parent. In Mendelian inheritance, dominant alleles tend to be expressed. Another way to look at it: If eye color was treated as a simple gene trait (it is not), then the gene would be the area on the chromosome that codes for eye color. However, the alleles would be the different forms: blue eyes, brown eyes, etc. In reality, eye color is not a single gene trait. This means that there are other genes that influence eye color. The ability to taste PTC may be influenced by other genes as well.

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