Biology HL
Biology HL
4
Chapters
553
Notes
Theme A - Unity & diversity
Theme A - Unity & diversity
Theme B - Form & Function
Theme B - Form & Function
Theme C - Interaction &  Interdependence
Theme C - Interaction & Interdependence
Theme D - Continuity & Change
Theme D - Continuity & Change
IB Resources
Theme A - Unity & diversity
Biology HL
Biology HL

Theme A - Unity & diversity

Unlocking Evolution The Molecular Clock & DNA Sequence Alignment

Word Count Emoji
621 words
Reading Time Emoji
4 mins read
Updated at Emoji
Last edited on 14th Jun 2024

Table of content

Hello, Biology enthusiasts! Today, we'll go on a journey exploring molecular clocks, DNA sequence alignments, and how these concepts can help us understand the evolution of different species. Let's get started!

The tick-tock of the molecular clock

What is a molecular clock?

The molecular clock is a method used to estimate the time since two species diverged from a common ancestor. This estimate is based on the assumption that DNA mutations (i.e., changes in the base sequence of DNA) accumulate at a constant rate over time.

 

🕰️ Fun fact: This is like estimating how long someone has been cooking by looking at the amount of soup that has evaporated from the pot!

Mutation rates & sequence differences

The more sequence differences there are between two species, the longer ago they diverged. But remember, the "tick-tock" of this molecular clock isn't always consistent - it can be influenced by factors like the length of the generation time, population size, selective pressure, and more.

 

🚀 To Infinity and Beyond: For example, fruit flies have a much faster mutation rate than humans because they reproduce more quickly. So, even though we've been around for a similar amount of time, fruit flies have more generations, and therefore, more opportunities for mutations.

Practical application - our evolutionary timeline

Using these principles, scientists have estimated that humans split from our nearest living relatives about 4.5 million years ago! Meanwhile, common chimpanzees and bonobos split more recently, around one million years ago. Similarly, by analyzing mitochondrial DNA, we have estimated that our most recent common human ancestor lived around 150,000 years ago.

 

🌳 Family Tree Fun: Think of your family tree – the further back in time you go, the more different branches you find. It's the same with our genetic family tree!

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IB Resources
Theme A - Unity & diversity
Biology HL
Biology HL

Theme A - Unity & diversity

Unlocking Evolution The Molecular Clock & DNA Sequence Alignment

Word Count Emoji
621 words
Reading Time Emoji
4 mins read
Updated at Emoji
Last edited on 14th Jun 2024

Table of content

Hello, Biology enthusiasts! Today, we'll go on a journey exploring molecular clocks, DNA sequence alignments, and how these concepts can help us understand the evolution of different species. Let's get started!

The tick-tock of the molecular clock

What is a molecular clock?

The molecular clock is a method used to estimate the time since two species diverged from a common ancestor. This estimate is based on the assumption that DNA mutations (i.e., changes in the base sequence of DNA) accumulate at a constant rate over time.

 

🕰️ Fun fact: This is like estimating how long someone has been cooking by looking at the amount of soup that has evaporated from the pot!

Mutation rates & sequence differences

The more sequence differences there are between two species, the longer ago they diverged. But remember, the "tick-tock" of this molecular clock isn't always consistent - it can be influenced by factors like the length of the generation time, population size, selective pressure, and more.

 

🚀 To Infinity and Beyond: For example, fruit flies have a much faster mutation rate than humans because they reproduce more quickly. So, even though we've been around for a similar amount of time, fruit flies have more generations, and therefore, more opportunities for mutations.

Practical application - our evolutionary timeline

Using these principles, scientists have estimated that humans split from our nearest living relatives about 4.5 million years ago! Meanwhile, common chimpanzees and bonobos split more recently, around one million years ago. Similarly, by analyzing mitochondrial DNA, we have estimated that our most recent common human ancestor lived around 150,000 years ago.

 

🌳 Family Tree Fun: Think of your family tree – the further back in time you go, the more different branches you find. It's the same with our genetic family tree!

Unlock the Full Content! File Is Locked Emoji

Dive deeper and gain exclusive access to premium files of Biology HL. Subscribe now and get closer to that 45 🌟