IMG_0901.jpeg

# Lesson 2: Cell Anatomy ## DNA - DNA contains the information that directs protein synthesis, a process called *gene expression*. - A DNA molecule consists of *nucleotides* joined together to form two nucleotide strands. - The two strands are connected and resemble a ladder that is twisted around...

# Lesson 2: Cell Anatomy ## DNA - DNA contains the information that directs protein synthesis, a process called *gene expression*. - A DNA molecule consists of *nucleotides* joined together to form two nucleotide strands. - The two strands are connected and resemble a ladder that is twisted around its long axis. - Each nucleotide consists of a 5-carbon sugar, a *phosphate group*, and a *nitrogenous base*. - Each nucleotide on one DNA strand has a specific bonding pattern to another nucleotide on the opposite strand. - A *gene* is a sequence of nucleotides that provides a chemical set of instructions for making a specific protein. ## Gene Expression - Gene expression, which is protein synthesis, involves *transcription* and *translation*. - *Transcription* involves copying DNA into messenger RNA. - *Translation* involves messenger RNA being used to produce a protein. ## Transcription - Takes place in the nucleus of the cell. - DNA determines the structure of mRNA through transcription. - During transcription, the double strands of a DNA segment separate, and DNA nucleotides of the gene pair with RNA nucleotides that form the mRNA. - DNA contains one of the following organic bases: thymine, adenine, cytosine, or guanine. - Messenger RNA (mRNA) contains *uracil*, adenine, cytosine, or guanine. - DNA nucleotides pair only with specific RNA nucleotides: - DNA's thymine = RNA's adenine. - DNA's adenine = RNA's uracil. - DNA's cytosine = RNA's guanine. - DNA's guanine = RNA's cytosine.