What is a codon? Above it shows how we read triplets, codons, and amino acids in a READING FRAME. For instance if we looked at the codons out of ‘reading frame’ and didn’t start and end where we are suppose to, it would not transcribe or translate correctly.

11.3 Section Summary 6.3 – pages Mutations Any change in DNA sequence is called a mutation. Mutations can be inherited, caused by spontaneous errors, or caused by external agents (mutagens).

11.3 Section Summary 6.3 – pages Mutations HAVE to be on sex cells (gametes) in order to be passed on to offspring. Some mutations are inherited from parents If a sperm or egg cell has a mutation and is fertilized, the altered gene would become part of the complete genetic makeup of the offspring. Every cell in that person would contain the mutation.

11.3 Section Summary 6.3 – pages A mutation may produce a new trait or it may result in a protein that does not work correctly. Sometimes, the mutation results in a protein that is nonfunctional, and the embryo may not survive. In some rare cases a gene mutation may have positive effects. (For instance, a mutation that caused an owl to have bigger eyes). Mutations in reproductive cells

11.3 Section Summary 6.3 – pages Sometimes a mutation can have no effect on a phenotype at all. For instance, if a codon sequence was suppose to be AUU Why would it have no effect on the person if a mutation caused the codon sequence to be AUC This is called a silent mutation.

11.3 Section Summary 6.3 – pages A point mutation is when one single base in DNA is replaced by another. Also called a substitution mutation. Result: A change in a single nitrogenous base to another will change the codon, and thus may change the amino acid in that reading frame (missense). WHICH CAN DO WHAT TO A PROTEIN? Types of Mutations THE DOG BIT THE CAT. THE DOG BIT THE CAR. Does this one letter change the meaning of the entire sentence?

11.3 Section Summary 6.3 – pages Normal Point mutation mRNA Protein Stop mRNA Protein Replace G with A Because one base was changed from a G to an A, it caused the wrong amino acid to be put in the protein. It is called a point mutation, because it happens at one point.

11.3 Section Summary 6.3 – pages An example of a point mutation, is sickle-cell disease. Sickle-cell diseases cause the red blood cells to be deformed. The result is that they get stuck in the blood vessels, depriving tissues of oxygen, causing strokes, and blood clots.

11.3 Section Summary 6.3 – pages A point mutation takes place when a single nitrogenous base (letter) is changed at one point. Types of Mutations THE DOG BIT THE CAT. THE DOG BIT THE CAR. What would happen if a single nitrogenous base was added or deleted? THE DOG BIT THE CAT. THD OGB ITT HEC AT. Is this a problem? WHAT HAPPENED?

11.3 Section Summary 6.3 – pages A mutation in which a single base is added or deleted from DNA is called a frameshift mutation because all the codons shift down by one base. Also called a insertion OR deletion mutation. Deletion of U Types of Mutations

11.3 Section Summary 6.3 – pages Deletion of U Instead of just one amino acid being wrong, this changes ALL the amino acids after the mutation (A LOT OF MISSENSE) This potentially causes much bigger problems than a point mutation. Types of Mutations Result:

11.3 Section Summary 6.3 – pages Frameshift mutations can cause severe genetic diseases like Cystic Fibrosis and Lou Gehrig’s Disease. Frameshift mutations Lou Gehrig’s Disease (ALS- amyotrophic lateral sclerosis) is a progressive neurological disease. Affects nerve cells used for voluntary muscle control Lou GehrigStephen Hawking

Lou Gehrig’s Disease, or Amyotrophic Lateral Sclerosis (ALS) is caused by a frameshift mutation on chromosome 21. Human Karyotype With ALS, there is a deletion of a Cytosine on this gene. Every other base moves down, making all the amino acids incorrect after that.

Section 12.1 Summary – pages Cystic fibrosis (CF) is one of the most common fatal genetic disorders among Americans. It affects the lungs and digestive tract Cystic Fibrosis Due to a defective protein in the plasma membrane, cystic fibrosis results in the formation and accumulation of thick mucus in the lungs and digestive tract. NORMAL LUNG

Cystic Fibrosis is caused by a frameshift mutation on chromosome 7. Three nitrogenous bases are deleted to cause this mutation in the amino acid sequence.

How could a chart like this be useful for scientists, doctors, or the individual themself?

Karyotype: A photomicrograph of chromosomes arranged in homologous pairs by size.

Homologue chromosomes are the same size, have the same centromere position, staining-band pattern, and carry the same genes (one is inherited from each parent) They are numbered according to size.

Karyotypes are valuable in identifying gender, unusual chromosome shapes, or unusual amounts of chromosomes.

Section 12.3 Summary – pages Down syndrome is a genetic disorder caused by an extra chromosome 21 Down syndrome: Trisomy 21

Section 12.3 Summary – pages Down syndrome: Trisomy 21 The incidence of Down syndrome births is higher in older mothers, especially those over 40. Extra chromosome on 21 1 in every 1100 live births Range from mild to severe physical and mental disabilities

Section 12.3 Summary – pages

Turners Syndrome Absence of one X chromosome Occurs in 1 out of every 2,500 live female births. Physical characteristics No mental disability