Structure of DNA “ Twisted ladder ” or “ spiral Staircase ” “ Side of Ladder ” – Deoxyribose(sugar) alternating with phosphates “ Rung of Ladder ” – Nitrogen Bases: Adenine, Thymine, guanine, cytosine A  T ; G  C….ALWAYS!!!!!

Replication of DNA DNA molecule unwinds and separate. Nitrogen bases floating in the nucleus pair up on each half of the DNA molecule. Each new DNA molecule exactly matches the original order

DNA Connection Main Function of Genes  control production of proteins in cells Proteins  Determine traits of organism Genetic Code – Order of three Nitrogen bases on a Gene code for a specific amino acid – Amino Acid – building blocks of Proteins – Order of Bases = Order of Amino Acids = build specific protein

How Cells Make Protein Protein Synthesis- – Production of protein – Cell uses information from a gene on a chromosome to made a specific protein – Takes place on the Ribosomes Chromosomes are in the Nucleus…How does the information get out into the cytoplasm?

How Cells Make Protein RNA- (ribonucleicacid) – Carries the genetic code from the DNA in the nucleus to the cytoplasm – RNA vs DNA * 1 strand* 2 strands * Uracil* Thymine

Messenger RNA (mRNA) – Copies code from DNA (nucleus) – Carries code to ribosome (cytoplasm) – Attaches & gives code to ribosome (cytoplasm) Transfer RNA (tRNA) – Find and Bring the amino acids “code” asks for to the ribosome – Adds Amino Acid to the growing protein chain

Steps of Protein Synthesis Step 1 – Strands of DNA to separate Step 2 – Messenger RNA bases pair up with the newly single DNA to form Messenger RNA strand. Step 3 – Messenger RNA leaves nucleus, enters cytoplasm, attaches to a ribosome, gives ribosome code for protein

Steps of Protein Synthesis Step 4 – Transfer RNA read the “ code ” from the messenger RNA and pair up using the 3-letter codes (nitrogen bases) – Transfer RNA carry specific Amino Acids Step 5 – Transfer RNA puts amino acids along growing protein chain – Once Amino Acid is released, transfer RNA released back into cytoplasm to continue.

Mutations ANY change in a gene or chromosome Due to an incorrect protein made during protein synthesis As a result, the phenotype may be different 2 Effects of Mutations: Harmful vs Helpful 1. Small Change in Organisms Heredity 2. Chromosomes do not Separate Correctly during Meiosis – Too many OR Too few chromosomes 3. In the Body Cell – only affects the cell that carries it 4. In the Sex Cell – Passed on to Offspring and Possibly the Phenotype

Effects of Mutations Harmful – Mutation reduces the organism’s chance for survival and reproduction White Buffalo Calf (more visible  predators) Cancer Helpful – Mutation improves an organism’s chance for survival and reproduction Resistant to certain antibiotics improve a bacteria’s ability to survive and reproduce Used to genetically engineer better food.

Other Mutations cystic fibrosis sickle cell anemia Tay-Sachs disease Phenylketonuria color-blindness