DNA, Mutations, and Genetic Variation
DNA carries the genetic instructions for living organisms. Mutations are changes in DNA sequences that can alter proteins, affect traits, and drive genetic variation in populations.
What You Need to Know
Key Concept Diagram
DNA is a double helix made of nucleotide base pairs: adenine-thymine (A-T) and guanine-cytosine (G-C)
A gene is a section of DNA that codes for a specific protein; mutations change the base sequence of a gene
Mutations can be substitutions (one base swapped), insertions, or deletions of bases
Most mutations are neutral or repaired, but some cause disease or provide an evolutionary advantage
Key Vocabulary
DNA
Deoxyribonucleic acid; the molecule in cells that carries genetic information in a double-helix structure
Mutation
A change in the nucleotide sequence of DNA; can be caused by errors in replication, radiation, or chemical exposure
Gene
A specific sequence of DNA bases that codes for a particular protein and determines a heritable trait
Protein synthesis
The process by which DNA instructions are used to build proteins via transcription and translation
Knowledge Check
Select the correct answer for each question. Click "Check Answer" to see if you are right.
Question 1
Which base pairing rule applies in DNA?
Question 2
A mutation that changes one DNA base to a different base is called a:
Question 3
Why are mutations important for evolution?
Key Concepts Summary
- ●DNA is a double helix made of nucleotide base pairs: adenine-thymine (A-T) and guanine-cytosine (G-C)
- ●A gene is a section of DNA that codes for a specific protein; mutations change the base sequence of a gene
- ●Mutations can be substitutions (one base swapped), insertions, or deletions of bases
- ●Most mutations are neutral or repaired, but some cause disease or provide an evolutionary advantage