DNA and Genetics
DNA (deoxyribonucleic acid) carries genetic information in all living cells. Genetics studies how traits are inherited from parents to offspring. Understanding DNA helps explain variation, inheritance, and evolution.
What You Need to Know
Key Concept Diagram
DNA is a double helix made of four bases: A, T, G, C. A pairs with T; G pairs with C
Genes are sections of DNA that code for specific proteins and traits
Chromosomes are packages of DNA; humans have 46 chromosomes in 23 pairs
Dominant traits are expressed when at least one dominant allele is present; recessive traits require two recessive alleles
Key Vocabulary
DNA
Deoxyribonucleic acid; the molecule that carries genetic instructions for development and function
Gene
A segment of DNA that codes for a specific protein or trait
Allele
One of two or more versions of a gene found at the same position on a chromosome
Dominant
An allele whose trait is expressed even when only one copy is present
Knowledge Check
Select the correct answer for each question. Click "Check Answer" to see if you are right.
Question 1
In DNA, which base pairs with Adenine (A)?
Question 2
A person inherits one dominant allele (R) and one recessive allele (r) for a trait. They will:
Question 3
What is the relationship between genes and proteins?
Key Concepts Summary
- ●DNA is a double helix made of four bases: A, T, G, C. A pairs with T; G pairs with C
- ●Genes are sections of DNA that code for specific proteins and traits
- ●Chromosomes are packages of DNA; humans have 46 chromosomes in 23 pairs
- ●Dominant traits are expressed when at least one dominant allele is present; recessive traits require two recessive alleles