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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 • 1. Small Change in • ANY change in a gene or Organisms Heredity chromosome • 2. Chromosomes do not • Due to an incorrect protein Separate Correctly during made during protein synthesis • As a result, the phenotype may Meiosis be different • 2 Effects of Mutations: Harmful vs Helpful – 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