BellRinger IN YOUR OWN WORDS Write a couple

Bell-Ringer • IN YOUR OWN WORDS… Write a couple of sentences explaining WHY m. RNA, t. RNA, and r. RNA are important to the synthesis of proteins.

Essential Question • How can mutations lead to dysfunctions in the body?

Mutations • Any change in a genetic nucleotide sequence is called a mutation. • Mutations can be caused by errors during DNA replication, transcription, translation, or cellular division.

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

Mutations in reproductive cells • 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).

• Sometimes a mutation can have no effect 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

Some mutations occur randomly in BODY CELLS (any cell that is not a sex cell) • What happens if powerful radiation hits the DNA of a body cell, such as in skin, muscle, or bone? Will that affect this person’s offspring? • If a body cell’s DNA is changed, this mutation would not be passed on to offspring. • However, the mutation may cause problems for the individual.

Types of Mutations • A point mutation occurs when a nucleotide is substituted for another. (For instance, if there is supposed to be an Adenine, but a Guanine is placed in the sequence instead. ) THE DOG BIT THE CAT. THE DOG BIT THE CAR. • Result: A change in a single nitrogenous base can change the entire structure of a protein causing it to not function properly.

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

• 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.

Types of Mutations A point mutation takes place when a single nitrogenous base (letter) is changed at one point. THE DOG BIT THE CAT. THE DOG BIT THE CAR. What would happen if a single nitrogenous base (letter) is deleted? HA WH PP AT EN ED ? THE DOG BIT THE CAT. THD OGB ITT HEC AT. Is this a problem?

Types of Mutations • A mutation in which a nucleotide is added or deleted from a sequence, it is called a frameshift mutation because all the nucleotides shift down. Deletion of U

Types of Mutations Result: • Instead of just one amino acid being wrong, this changes ALL the amino acids after the mutation. • This causes much bigger problems than a point mutation. Deletion of U

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

Lou Gehrig’s Disease, or Amyotrophic Lateral Sclerosis (ALS) is caused by a frameshift mutation on chromosome 21. 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. Human Karyotype

Cystic Fibrosis • Cystic fibrosis (CF) is one of the most common fatal genetic disorders among Americans. • It affects the lungs and digestive tract NORMAL LUNG • 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.

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.

Causes of Mutations • Many mutations are caused by factors in the environment, such as radiation, chemicals, and even high temperatures. • Any external agent that can cause a change in DNA is called a mutagen.

Repairing DNA • Enzymes proofread the DNA and replace incorrect nucleotides with correct nucleotides. • These repair mechanisms work extremely well, but they are not perfect. • The greater the exposure to a mutagen such as UV light, the more likely that a mistake will not be corrected.

Activity-Amino Acid Bead Key Methionine- Purple Glycine- Yellow Serine- Pink Threonine- Black Histidine- Green Arginine. Leucine. Stop- Blue Red White • Transcribe your DNA into an m. RNA strand • Use your codon chart to translate the m. RNA to an amino acid sequence • Use the Key above to match your amino acids with the right color bead • Bring it to me for a grade

Go play these games: • www. quia. com/ba/94095. html • nobelprize. org/educational_games/medicine/ dna_double_helix/ • www. quia. com/rr/319768. html • www. quia. com/mc/330604. html

Question 1 Any change in DNA sequences is called a _______. A. replication B. mutation C. transcription D. translation The answer is B.

Question 2 Which is more serious, a point mutation or a frameshift mutation? Why? Answer A frameshift mutation is more serious than a point mutation because it disrupts more codons than a point mutation.

Question 3 Why would a mutation on someone’s skin cell not be passed on to their offspring? Answer Only mutations on gametes can be passed to offspring.