Biology SL
Biology SL
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 D - Continuity & Change
Biology SL
Biology SL

Theme D - Continuity & Change

Consequences of Base Substitutions from Neutral to Lethal Impacts

Word Count Emoji
448 words
Reading Time Emoji
3 mins read
Updated at Emoji
Last edited on 5th Nov 2024

Table of content

Base Substitution Mutations

What are they? Changes in a single DNA base.

Consequences

Mostly neutral or harmful, and sometimes lethal.

Mutations in Non-coding DNA

  • No major effect because they aren’t involved in making proteins.
  • Example: Imagine if you got a typo in the white space of your assignment. Your teacher might not notice it because it doesn't change the message!

Types of Base Substitution Mutations

  • Same-Sense Mutations

    • Changes one codon for an amino acid into another codon but still codes for the same amino acid.
    • Real-world Example: It's like saying "Hello" or "Hi". Different words but the same greeting!
    • How is this possible? Due to the redundancy of the genetic code. So, AGC to AGT both mean "Hey, make a serine!"
    • These mutations don't affect the phenotype. But, can pave the way for a future mutation.
  • Nonsense Mutations

    • Converts a normal codon into a stop codon.
    • Real-world Example: Imagine reading a book, and mid-sentence, there's a full stop. Confusing, right?
    • Result? The protein gets cut short and usually malfunctions. The aftermath? Depends on the job of that protein!
  • Mis-sense Mutations

    • Changes one amino acid in a protein.
    • Impact? Depends!
      • If the new amino acid is like its old roommate (similar properties), things might be okay.
      • But, if not? Trouble ensues. For instance, sickle cell disease is a mean result of such mutations.
    • Silver Lining? A tiny fraction of these mutations can actually boost protein function, kinda like a surprise superhero transformation! Though rare, these are evolution's little gifts!

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IB Resources
Theme D - Continuity & Change
Biology SL
Biology SL

Theme D - Continuity & Change

Consequences of Base Substitutions from Neutral to Lethal Impacts

Word Count Emoji
448 words
Reading Time Emoji
3 mins read
Updated at Emoji
Last edited on 5th Nov 2024

Table of content

Base Substitution Mutations

What are they? Changes in a single DNA base.

Consequences

Mostly neutral or harmful, and sometimes lethal.

Mutations in Non-coding DNA

  • No major effect because they aren’t involved in making proteins.
  • Example: Imagine if you got a typo in the white space of your assignment. Your teacher might not notice it because it doesn't change the message!

Types of Base Substitution Mutations

  • Same-Sense Mutations

    • Changes one codon for an amino acid into another codon but still codes for the same amino acid.
    • Real-world Example: It's like saying "Hello" or "Hi". Different words but the same greeting!
    • How is this possible? Due to the redundancy of the genetic code. So, AGC to AGT both mean "Hey, make a serine!"
    • These mutations don't affect the phenotype. But, can pave the way for a future mutation.
  • Nonsense Mutations

    • Converts a normal codon into a stop codon.
    • Real-world Example: Imagine reading a book, and mid-sentence, there's a full stop. Confusing, right?
    • Result? The protein gets cut short and usually malfunctions. The aftermath? Depends on the job of that protein!
  • Mis-sense Mutations

    • Changes one amino acid in a protein.
    • Impact? Depends!
      • If the new amino acid is like its old roommate (similar properties), things might be okay.
      • But, if not? Trouble ensues. For instance, sickle cell disease is a mean result of such mutations.
    • Silver Lining? A tiny fraction of these mutations can actually boost protein function, kinda like a surprise superhero transformation! Though rare, these are evolution's little gifts!

Unlock the Full Content! File Is Locked Emoji

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