DEOXYRIBONUCLEIC ACID The Double Helix

Why does DNA replicate? Cells copy genetic information before cell division so that each new cell has a complete set of DNA

3 steps to DNA Replication UNZIP: DNA Helicase “unzips” the strands of DNA breaking the hydrogen bonds.

2) BASE PAIRING: DNA Polymerase bonds free nucleotides with nucleotides from parent strand

3. Joining Nucleotides: Ligase bonds nucleotides together. This result in 2 identical DNA molecules.

Semi Conservative Replication: New DNA molecule contains 1 new strand and 1 old strand.

DNA replication

2.   3.   1.

Central Dogma of Biology:

Protein Synthesis occurs in two steps: 1) Transcription: DNA RNA 2) Translation: RNA Protein

Makes a temporary copy of DNA Transcription Makes a temporary copy of DNA

Turn to a Partner List all the similarities and differences with DNA and RNA

RNA Structure RNA differs from DNA in 3 ways: RNA is a single strand RNA has the sugar ribose RNA has the nitrogen base uracil instead of thymine.

3 Types of RNA Messenger RNA (mRNA) Carries copy of instructions for making protein from nucleus to ribosome

2. Ribosomal RNA (rRNA) Structural component of ribosomes

3. Transfer RNA (tRNA) Transfers an amino acid to the ribosome to be added to the protein.

Talk to a Partner List the 3 types of RNA & their functions

Transcription: The process An enzyme unzips DNA As DNA unzips, free RNA nucleotides pair with the DNA nucleotides. When base pairing is done, the new mRNA breaks away. mRNA leaves the nucleus and enters the cytoplasm

Explain the process of transcription Talk to a Partner Explain the process of transcription

Transcription Animation

Types of RNA RNA can be Messenger RNA Ribosomal RNA Transfer RNA also called which functions to also called which functions to also called which functions to mRNA Carry instructions rRNA Combine with proteins tRNA Bring amino acids to ribosome from to to make up DNA Ribosome Ribosomes

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Translation RNA to PROTEIN

Steps to Translation

mRNA attaches to the ribosome. 2. The tRNA molecule with the correct anticodon attaches to the mRNA codon.

***This process continues until a STOP codon is reached. 3.The mRNA slides through the ribosome to the next codon and another tRNA comes and attaches to mRNA. 4. The 1st tRNA releases its amino acid to attach to the 2nd amino acid on using a peptide bond. ***This process continues until a STOP codon is reached.

Translation: RNA to PROTEIN Talk to a Partner Translation: RNA to PROTEIN

Translation into a Protein Proteins are made by joining amino acids with a peptide bond into long chains called polypeptides. The genetic code is read three letters at a time, so that each “word” of the coded message is three mRNA bases long. This 3-letter “word” is known as a codon. Each codon corresponds to a particular amino acid (the anti-codon on tRNA).

Decoding codons into amino acids

Met- Thre- Gly- Ser -stop Example: Template DNA: TAC TGG CCT TCG ACT mRNA: tRNA: Amino Acids: AUG ACC GGA AGC UGA (Codon) (Anticodon) UAC UGG CCU UCG ACU Met- Thre- Gly- Ser -stop

Translation: RNA to PROTEIN Talk to a Partner Translation: RNA to PROTEIN

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Translation Animation

Central Dogma of Biology: