DNA, RNA & Protein Synthesis Cheat Sheet

A printable reference covering DNA structure, RNA types, base pairing, transcription, translation, codons, and protein synthesis for grades 10-11.

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This cheat sheet covers how genetic information is stored in DNA, copied into RNA, and used to build proteins. Students need these ideas to understand inheritance, gene expression, mutations, and many topics in modern biology. It connects molecular structure to the central dogma, which is the flow of information from DNA to RNA to protein. The most important concepts are complementary base pairing, transcription, translation, and the genetic code. DNA uses A-T and C-G base pairs, while RNA uses A-U and C-G base pairs. During transcription, RNA polymerase builds mRNA from a DNA template strand. During translation, ribosomes read mRNA codons so tRNA can bring amino acids in the correct order.

Key Facts

The central dogma is DNA -> RNA -> protein.
In DNA, adenine pairs with thymine and cytosine pairs with guanine, so A = T and C = G in double-stranded DNA.
In RNA, adenine pairs with uracil and cytosine pairs with guanine, so A pairs with U and C pairs with G.
A DNA nucleotide contains deoxyribose sugar, a phosphate group, and one nitrogen base: A, T, C, or G.
An RNA nucleotide contains ribose sugar, a phosphate group, and one nitrogen base: A, U, C, or G.
During transcription, the mRNA sequence is complementary to the DNA template strand and matches the DNA coding strand except U replaces T.
A codon is a group of 3 mRNA bases, and each codon usually codes for one amino acid.
Translation begins at the start codon AUG and ends at a stop codon: UAA, UAG, or UGA.

Vocabulary

DNA: DNA is the double-stranded molecule that stores genetic instructions in the sequence of its bases.
RNA: RNA is a usually single-stranded nucleic acid that helps copy and use genetic information to make proteins.
Transcription: Transcription is the process of making an RNA copy from a DNA template.
Translation: Translation is the process in which a ribosome reads mRNA codons to build a protein.
Codon: A codon is a sequence of three mRNA bases that specifies an amino acid or a stop signal.
Anticodon: An anticodon is a three-base sequence on tRNA that pairs with a matching mRNA codon.

Common Mistakes to Avoid

Using T in RNA sequences is wrong because RNA contains uracil instead of thymine, so A pairs with U during RNA base pairing.
Confusing the coding strand with the template strand is wrong because mRNA is complementary to the template strand but nearly identical to the coding strand except U replaces T.
Reading codons from the wrong direction is wrong because mRNA is read in groups of three from the 5' end to the 3' end during translation.
Assuming every mutation changes a protein is wrong because some mutations are silent or occur outside a coding region.
Forgetting the start codon is wrong because translation normally begins at AUG, which sets the reading frame for the rest of the protein.

Practice Questions

1 A DNA template strand is TAC GGA CTT. What mRNA sequence is made during transcription?
2 An mRNA sequence is AUG UUU GGC UAA. How many amino acids are added before translation stops?
3 A double-stranded DNA sample has 24 percent adenine. What percent of the sample is thymine, cytosine, and guanine?
4 Explain why a substitution mutation in DNA might not change the amino acid sequence of a protein.