GENE EXPRESSION

Root Words to Know

Trans = across Script = write

Poly = many Synth = make

First, Let’s Review

• Prokaryotes, eukaryotes, and viruses all contain genetic information in the form of DNA molecules.

First, Let’s Review

• DNA is made of nucleotides, which contain deoxyribose sugar, phosphate, and nitrogen bases. The four nitrogen bases are adenine, thymine, guanine, and cytosine (A, T, G, and C).

nucleotide

Gene Expression is a Regulated Process

• Like books in a library, the purpose of genes is to store information. Each cell in your body contains an entire library of genetic information, but not all of it is expressed.

Gene Expression is a Regulated Process• By expressing only

certain genes, cells can become specialized for a certain function. For example, a muscle cell would express different genes than a nerve cell because they have different functions in your body.

So, How Does It All Happen?1. The cell receives a signal that a protein is

needed. This is usually a molecule that attaches to the cell membrane.

2. The message is sent through the cell into the nucleus, where the DNA is found.

So, How Does It All Happen?3. Several proteins (including RNA polymerase)

bind to the DNA and begin the process of transcription.

• TRANSCRIPTION: a complementary strand of messenger RNA (mRNA) is made based on the DNA template.

Example:

DNA triplets: GAT CCA ATG AGG

mRNA codons: ____________________

So How Does It All Happen?4. The mRNA is transported out of the nucleus and

into the cytoplasm

5. The mRNA binds to a ribosome and transfer RNA (tRNA) brings amino acids to the ribosome

• TRANSLATION: mRNA is translated into an amino acid sequence (a protein)

So How Does It All Happen?6. The amino acids are bonded together into a

polypeptide

7. The polypeptide is folded into a protein and transported to its final destination

Summary of Protein Synthesis

TRANSCRIPTION: _________ __________

TRANSLATION: _________ __________

Practice

Use the chart below to translate this mRNA into amino acids: mRNA codons: AUG UAC GAU UAG_________ __________ __________ ___________

Cool Video:

http://www.youtube.com/watch?v=41_Ne5mS2ls

DNA Rap:

http://www.youtube.com/watch?v=d1UPf7lXeO8