Molecular clock

High school (ages 12+)
Science & Technology

Name:

Date:

Step 1 · Read the article

Open the article and read it at the level above. Then answer the questions below in your own words.

https://smallwhale.org/articles/molecular-clock

Write what each word means, using the article.

Do not copy the article. Write two things you learned, the way you would explain them to a friend.

Answers below are taken from the article’s stored facts, so they match what the student read.

1. What is the data sources?Nucleotide sequences (DNA, RNA) and amino acid sequences (proteins)
2. What is the calibration method?Utilizes fossil records or biogeographic events to anchor divergence time estimates
3. How does the molecular clock work?Scientists compare DNA, RNA, or protein sequences from different species. The more differences, the longer ago they shared a common ancestor.
4. Why do scientists think mutations happen at a constant rate?Because experiments in the 1960s and later studies showed that the number of changes in proteins and DNA tends to increase steadily over time.

Homologous Proteins: Proteins in different species that share a common evolutionary origin.
Phylogenetic Tree: A branching diagram showing the evolutionary relationships among species.
Rate Heterogeneity: The variation in mutation rates across different genes or lineages.