From DNA to Proteins

DNA contains __________________ and the instructions for making ________. Why is DNA important? genetic information proteins

PROTEINS???? Proteins are the workhorse of the cells. Antibodies Hormones Hemoglobin

Where in the cell are proteins made? ribosomes Ribosomes & Rough ER Rough ER

Where is DNA? ribosomes Nucleus Rough ER DNA

Does DNA travel outside the nucleus?Never!!! DNA never ever leaves the nucleus!

Instead, the cell copies a section of DNA called mRNA. mRNA exits the nucleus and attaches to a ribosome which makes the protein.

Transcription: Translation: DNA mRNA protein Protein synthesis involves two steps:

A gene is a section of DNA.

nucleus ribosome DNA A T T C G G A C T G C G A T A A T A A G C C T G A C G C T A T T gene (section of DNA) mRNA copy of gene exits the nucleus DNAmRNA TRANSCRIPTION

DNAmRNAProteinmRNA TRANSCRIPTION TRANSLATION nucleus ribosome exits nucleus DNA A T T C G G A C T G C G A T A A T A A G C C T G A C G C T A T T mRNA mRNA attaches to ribosome Protein is made protein

RNA, like DNA, is a ____________. RNA RNA nucleic acid RNA is also composed of ____________. nucleotides mRNA

RNA RNA 1.RNA is single stranded. DNA is double stranded. 2.The sugar in RNA is ribose, whereas the sugar in DNA is deoxyribose. 3. Both DNA and RNA contain four bases, but RNA contains Uracil (U), not thymine (T) RNA differs from DNA in three ways: Complementary base pairs in RNA are: A --- U C --- G

Let’s review transcription!

nucleus DNA A T T C A G A C T G C G A T A A T A A G C C T G A C G C T A T T 1.RNA polymerase binds to the gene’s “start site”. start DNA Polymerase RNA polymerase (an enzyme)

nucleus DNA A T T C A G A C T G C G A T A A T A A G C C T G A C G C T A T T 2.RNA polymerase unzips and separates the two strands of DNA. start

nucleus DNA A T T C A G A C T G C G A T A A T A A G C C T G A C G C T A T T start 3.RNA polymerase adds and links RNA nucleotides to one strand of DNA (DNA template). U C U G A G mRNA DNA template

nucleus DNA A T T C A G A C T G C G A T A A T A A G C C T G A C G C T A T T 4. RNA nucleotides are added until a “stop” signal is reached U C U G A G mRNA stop

nucleus DNA A T T C A G A C T G C G A T A A T A A G C C T G A C G C T A T T 5. mRNA strand detaches, exits the nucleus, and enters the cytoplasm. UCUGAG mRNA stop mRNA

DNAmRNAProteinmRNA TRANSCRIPTION TRANSLATION nucleus ribosome exits nucleus DNA A T T C G G A C T G C G A T A A T A A G C C T G A C G C T A T T mRNA mRNA attaches to ribosome Protein is made protein

TRANSLATION

mRNA Protein Translation is the process that converts the mRNA message into a protein.

Translation involves: a ribosome, mRNA tRNA. ribosome Where the protein is assembled.

Translation involves: a ribosome, mRNA tRNA. mRNA contains the instruction for making a particular protein.

The mRNA contains the instructions for making a particular protein. mRNA --- U U G G U U A G G U G G C U A codon These instructions are written as a series of three-nucleotides called codons. A codon is a three-nucleotide sequence in mRNA that codes for an amino acid.

Each codon along the mRNA strand corresponds to an ____________ (or a start/stop). amino acid Most amino acids are coded for by more than one codon.

mRNA -- U U G G U U A G G U G G C U A amino acids Underline the codons in mRNA 2. Determine the amino acids that correspond to each codon. leucinevalinearginine tryptophan leucine

Translation involves: mRNA a ribosome, tRNA. tRNA tRNA transports amino acids to the ribosome.

Transfer RNA (tRNA) molecules contain an anticodon on one end, and an amino acid on the other end. amino acid anticodon The anticodon is complementary to the mRNA codon.

DNAmRNAProteinmRNA TRANSCRIPTION TRANSLATION nucleus ribosome exits nucleus DNA A T T C G G A C T G C G A T A A T A A G C C T G A C G C T A T T mRNA mRNA attaches to ribosome Protein is made protein

TRANSLATION The tRNAs bring amino acids to the ribosome in the order dictated by the mRNA molecule. The codons on mRNA are complementary to the anticodons on the tRNAs. As the tRNAs bring amino acids to the ribosome, the amino acids are linked together, one by one, to form a protein.

Which molecule is this? tRNA

What is this process called? Translation

What is this process called? Transcription