Mutations Terms to study

1. Mutation 9. Transcription 2. Point mutation 10. Translation 3. Silent mutation 11. Translocation 4. Missense mutation 12. Duplication 5. Nonsense mutation 13. Deletion 6. Nondisjunction 14. Inversion 7. Protein synthesis 15. Codon 8. Semiconservative replication

Semiconservative Replication

The process in which the DNA molecule uncoils and separates into two strands. Each original strand becomes a template on which a new strand is constructed, resulting in two DNA molecules identical to the original DNA molecule. Mutations

• What are mutations? • Mutations are changes in the DNA sequence that affect genetic information. A permanent transmissible change of genetic material Types of Mutations – mistakes 1.Gene (point) Mutations – effects a single gene

2. Chromosomal mutations – most drastic, change in structure or # of chromosomes (affects many genes) Point Mutation

A single‐base substitution causing the replacement of a single‐base nucleotide with another nucleotide Types of point mutations include : silent mutation, missense mutation, and nonsense mutation Point Mutation

1. silent mutation- there is no change in an amino acid 2. missense mutation- there is a different amino acid 3. nonsense mutation- there is an insertion of a stop codon in the amino acid which stops protein synthesis Frameshift Mutation

• Inserting or deleting one or more nucleotides • Changes the “reading frame” like changing a sentence • Proteins built incorrectly Gene Mutations

• Point Mutations – changes in one or a few nucleotides – Substitution • THE FAT CAT ATE THE RAT • THE FAT HAT ATE THE RAT – Insertion • THE FAT CAT ATE THE RAT • THE FAT CAT XLW ATE THE RAT – Deletion • THE FAT CAT ATE THE RAT • THE FAT ATE THE RAT

Example: Sickle Cell Anemia

Normal Red Blood Cell Sickle Red Blood Cell • Red blood cells shaped like • Red blood cells form an a disc abnormal crescent shape • Hemoglobin (protien) • Hemoglobin (protein) is carries oxygen to all parts of abnormally shaped the body • don't move easily through your blood vessels • form clumps and get stuck in the blood vessels Chromosome Mutations • Changes in number and structure of entire chromosomes • Original Chromosome ABC * DEF • Deletion AC * DEF • Duplication ABBC * DEF • Inversion AED * CBF • Translocation ABC * JKL GHI * DEF Chromosomal Mutations

1. deletion, the loss of a segment of a chromosome and thus the loss of segment containing genes

2. duplication, when a segment of a chromosome is duplicated and thus displayed more than once on the chromosome Chromosomal Mutation

3. inversion, when a segment of a chromosome breaks off and reattaches in reverse order

4. translocation, when a segment of one chromosome breaks off and attaches to a nonhomologous chromosome

• Things that can cause mutations are called “mutagens”. • Known mutagens are ultraviolet light, cigarette smoking, certain chemicals like PCB’s, and other environmental factors.

Nondisjunction • Failure of chromosomes to separate during meiosis • Causes gamete to have too many or too few chromosomes • Disorders: – Down Syndrome – three 21st chromosomes – Turner Syndrome – single X chromosome – Klinefelter’s Syndrome – XXY chromosomes

Types of Gene Mutations • Include: –Point Mutations –Substitutions –Insertions –Deletions –Frameshift Point Mutation

• Change of a single nucleotide • Includes the deletion, insertion, or substitution of ONE nucleotide in a gene Likelihood of chromosomal mutations .1 in 1700 for mothers < 20. .1 in 1400 for mothers >20<30. .1 in 750 for mothers >30<35. .1 in 16 for mothers >45.