Catalyst 1.During which part of the cell cycle does DNA replicate? 2.What type of bonds hold the nitrogen bases of DNA together? 3.What type of bonds hold the sugar- phosphate backbone together?

Agenda Review – Protein Synthesis Codon Bingo Notes – Mutations SNORK DNA PROTEIN SYNTHESIS TEST TOMORROW

Protein Synthesis

DNA provides the instructions for making proteins. The Central Dogma of Biology tells us how proteins are made from DNA instructions. The order or sequence of bases in an mRNA molecule determines the order in which amino acids are joined together.

DNA’s instructions must be copied into a smaller form: messenger RNA (mRNA). This process is called transcription. RNA polymerase breaks the hydrogen bonds in DNA and uses it as a template to create a single strand of mRNA.

Base-pairing During Transcription Because RNA has the base uracil (U) instead of the thymine (T) in DNA, it has slightly different base-pairing rules.

Translation decodes mRNA to produce polypeptide chains (proteins) at the ribosome.

Codon charts show amino acids produced from codons DNA  mRNA  amino acid

Check yourself!!!

Agenda Review – Protein Synthesis Codon Bingo Notes – Mutations SNORK DNA PROTEIN SYNTHESIS TEST TOMORROW

Codon Bingo

Agenda Review – Protein Synthesis Codon Bingo Notes – Mutations SNORK DNA PROTEIN SYNTHESIS TEST TOMORROW

Mutations I can explain mutations.

Mutations A mutation is a change in a DNA sequence. Mutation leads to genetic VARIATION!

Types of Mutations Substitution – one base is swapped out for another. How does a substitution affect the overall amino acid sequence?

REAL WORLD Sickle Cell disease is the result of one nucleotide substitution Occurs in the hemoglobin gene – changes the normal red blood cells into cells that can be shaped like crescent moons Get stuck and block the blood vessels – Stopping flow of oxygen throughout the body 3cUic

Types of Mutations Insertion – an extra base pair(s) is added into a new place in the DNA How does an insertion affect the overall amino acid sequence?

Types of Mutations Deletion – Base pairs in the sequence are lost or deleted How does a deletion affect the overall amino acid sequence?

Types of Mutations Insertions and deletions are called frame shift mutations. DNA is “read” in 3-base codons in/dels change the reading frame A T G A C G T A A A T C G A C G T A A mutation!

Real World Cystic fibrosis – An inherited condition, cystic fibrosis affects the cells that produce mucus, sweat and digestive juices – These secreted fluids are normally thin and slippery » But in cystic fibrosis, a defective gene causes the secretions to become thick and sticky – Instead of acting as a lubricant, the secretions plug up tubes, ducts and passageways, especially in the lungs most common in white people but also occurs in Hispanics, African-Americans and some Native Americans It is rare in people of Asian and Middle Eastern origin.

Chromosomal Mutations

Chromosomal Mutation Klinefelter’s syndrome Failure of chromosomes to separate during meiosis – Causes gamete to have too many or too few chromosomes – XXY chromosomes » More feminine than masculine occurs in about 1 out of 1,000 males

Klinefelter’s Syndrome

Agenda Review – Protein Synthesis Codon Bingo Notes – Mutations SNORK DNA PROTEIN SYNTHESIS TEST TOMORROW

SNORK DNA