In this Grade 7 Life Science lesson from Chapter 5, students learn how DNA stores genetic information as a sequence of nucleotide bases — adenine, thymine, cytosine, and guanine — and how that sequence forms a triplet code used to specify amino acids for building proteins. The lesson also introduces DNA replication and the role of RNA in transferring information from DNA to produce specific proteins in the cell. Part of the Life Science textbook's unit on modern genetics, this lesson builds on students' prior knowledge of traits, genes, and inheritance.
Section 1
DNA and the Genetic Code
DNA uses a double helix (a twisted ladder shape) to store the blueprints for life.
The "rungs" of this ladder are made of four nucleotide bases—A, T, G, and C—which act like letters in a biological alphabet.
These bases follow strict base pairing rules (A always matches T, and C always matches G) to ensure that genetic instructions for building proteins are copied and stored accurately.
Section 2
Cells Copy DNA Through Replication
During replication, DNA strands separate and serve as templates. New nucleotides match to each strand (A with T, C with G), creating two identical DNA molecules, each containing one old and one new strand.
Section 3
RNA Translates DNA Code Into Proteins
Three types of RNA (mRNA, tRNA, and rRNA) work together to make proteins. mRNA copies DNA's code, ribosomes provide assembly sites, and tRNA delivers amino acids to build protein chains.
Section 4
Cells Assemble Proteins Using Amino Acids
Proteins are chains of amino acids that perform most cellular functions. DNA's triplet code specifies which of the twenty amino acids to use, allowing cells to build thousands of different proteins.
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Section 1
DNA and the Genetic Code
DNA uses a double helix (a twisted ladder shape) to store the blueprints for life.
The "rungs" of this ladder are made of four nucleotide bases—A, T, G, and C—which act like letters in a biological alphabet.
These bases follow strict base pairing rules (A always matches T, and C always matches G) to ensure that genetic instructions for building proteins are copied and stored accurately.
Section 2
Cells Copy DNA Through Replication
During replication, DNA strands separate and serve as templates. New nucleotides match to each strand (A with T, C with G), creating two identical DNA molecules, each containing one old and one new strand.
Section 3
RNA Translates DNA Code Into Proteins
Three types of RNA (mRNA, tRNA, and rRNA) work together to make proteins. mRNA copies DNA's code, ribosomes provide assembly sites, and tRNA delivers amino acids to build protein chains.
Section 4
Cells Assemble Proteins Using Amino Acids
Proteins are chains of amino acids that perform most cellular functions. DNA's triplet code specifies which of the twenty amino acids to use, allowing cells to build thousands of different proteins.
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter