DNA Structure and Function

DNA -deoxyribonucleic acid (blue print to make proteins and enzymes)

Bacteriophage Experiment -Bacteriophage- a virus that infects bacteria -bacteria stops reproducing and new viruses are made. Why? -virus injects its DNA into the Bacteria. -observing this helped lead to the discovery of DNA.

DNA Structure -”twisted ladder” called a double helix -two strands of DNA twisted around each other

Outside Structure -Outsides composed of alternating phosphates and sugars P P P P P P S SS S SS

Inside Structure -inside “steps” are bases adenine (A) guanine (G) cytosine (C) thymine (T) -A-T pair up -G-C pair up G P P P P P P S SS S SS TA CG C

Nucleotide Nucleotide – base, sugar, phosphate G P P P P P P S SS S SS TA CG C

Replication (synthesis) - DNA “unzips” into 2 strands and makes two new complementary strands(before mitosis and meiosis)

Protein Synthesis -DNA directs the making of proteins -Two steps: Transcription and Translation

Transcription -Transcription – the process of making an RNA copy of DNA -DNA cannot leave the nucleus -RNA- ribonucleic acid is a copy the DNA that can leave the nucleus.

Continued -RNA –single stranded, replaces Thymine (T) with Uracil (U) -mRNA- (m=messenger) made in transcription and goes to the ribosomes A-T-G-C-G-G-T DNA U-A-C-G-C-C-A mRNA -every 3 bases (letters) in mRNA is called a codon

Translation - translation-uses tRNA to make protein at the ribosome -tRNA is made of the opposite bases of mRNA. - Every three bases are called anticodons A-T-G-C-G-G-T DNA U-A-C-G-C-C-A mRNA A-U-G-C-G-G-U tRNA

Translation -Each anticodon brings a specific amino acid -tRNA tells ribosomes which amino acids to use to build proteins.