SB 2 Students will analyze how biological traits

SB 2. Students will analyze how biological traits are passed on to successive generations d. Describe the relationships between changes in DNA and potential appearance of new traits What are some mutagenic factors and what effects do they have on 1

LEQ#3: What are some mutagenic factors and what effects do they have on DNA? What are some mutagenic factors and what effects do they have on 2

Vocabulary to Know: • • • Mutagenic Factor Mutation Mutagen Pesticides Herbicides • • • Radiation X-Rays/ UV rays Chemicals Viruses Phenotype What are some mutagenic factors and what effects do they have on 3

Mutagenic Factors • Agents in the environment that can change DNA are called mutagenic factors – Also called mutagens What are some mutagenic factors and what effects do they have on 4

Mutagenic Factors • Examples – UV rays in sunlight (Natural factor) – Radiation (X-rays and Nuclear) – Industrial Chemicals • Pesticides: Chemical substance used to against any pests. • Herbicides: Chemical substance used to kill plants • Cigarettes – Biological agent • Antimicrobial or disinfectant • Viruses What are some mutagenic factors and what effects do they have on 5

What are some mutagenic factors and what effects do they have on 6

Effects on DNA • Mutagenic factors can cause mutations – Change in the DNA that affects the sequence of nitrogen bases in the DNA • Changes that occur in the DNA sequence may or may not lead to changes in an organism What are some mutagenic factors and what effects do they have on 7

What is a mutation? • Change in an organisms DNA is called a mutation. • Not uncommon • May or may not affect the phenotype of an organism – Physical characteristics • May or may not have an impact of offspring What are some mutagenic factors and what effects do they have on 8

Effects on organism • Human body has DNA repair enzymes that help find and fix mutations • Although, sometimes these enzymes don’t work and the mutation is not fixed – The DNA site for the production of that enzyme has been damaged by the mutation • Errors or mutations can build up overtime and eventually effect how the cell works. – Mutations are a significant cause of aging What are some mutagenic factors and what effects do they have on 9

Explain how mutagens can cause genetic mutations in spite of your body’s DNA repair enzymes. What are some mutagenic factors and what effects do they have on 10

Answer • Mutagens may produce so much damage that the repair enzymes cannot keep up with the repairs. What are some mutagenic factors and what effects do they have on 11

LEQ#4: What are the types of alterations that can occur during replication? What are some mutagenic factors and what effects do they have on 12

Vocabulary to Know: • • Point mutation Framshift mutation Gene mutation Chromosomal mutation • Substitutions • • • Deletion Duplication Inversion Translocation Nondisjunction Trisomy What are some mutagenic factors and what effects do they have on 13

Mutations • Two main types: – Gene Mutation • Mutation that causes a change in a single gene – Chromosomal Mutation • Mutation that involves the entire chromosome • Both can be caused by nature, random events, or environmental factors What are some mutagenic factors and what effects do they have on 14

Gene Mutations • Error in the sequence of nitrogen bases in a single gene – Remember: Codon (sequence of 3 nitrogen bases) corresponds to a particular amino acid • Two types of Gene Mutations: – Point mutation – Frame shift mutation What are some mutagenic factors and what effects do they have on 15

Gene Mutations • Error in the sequence of nitrogen bases in a single gene – Remember: Codon (sequence of 3 nitrogen bases) corresponds to a particular amino acid • Two types of Gene Mutations: – Point mutation – Frame shift mutation What are some mutagenic factors and what effects do they have on 16

Gene Mutation Point Mutation • Change in a single base is called a point mutation • Each of these words represents different amino acid. THE CAT ATE THE RAT • Now what would happen if you changed one letter? THE CAT ATE THE BAT • Still makes sense but the meaning is different – Effects are usually minimal if any at all • Example: Sickle Cell – GAG codon is changed to GTG – Inserts wrong amino acid What are some mutagenic factors and what effects do they have on 17

Gene Mutation Frameshift Mutation • Base is added/deleted is called a Frameshift mutation THE CAT ATE THE RAT Deleted one base: C THE ATA TET HER AT_ Added one base: C THE CCA TAT ETH ERA T • The statement makes no sense and the meaning is completely different – Effects much more severe than a point mutation – Codon for different amino acid What are some mutagenic factors and what effects do they have on 18

Wasting Syndrome • Gene mutation that results in the mutated form of myostatin protein. • Leads to overproduction of muscle tissue • Often seen in Belgian Blue and Piedmontese breeds of cattle What are some mutagenic factors and what effects do they have on 19

Explain why Frameshift mutations have a greater effect than do Point Mutations. What are some mutagenic factors and what effects do they have on 20

Answer • Point mutations typically affect only one codon (unless they create a premature stop codon). • A frame shift mutation affects all the codons in a gene that follow it. What are some mutagenic factors and what effects do they have on 21

Chromosomal Mutations • Changes in the number of chromosomes or their structure • Occur: Chromosomes fail to separate correctly during gamete production – Nondisjunction • Lead to abnormalities in offspring – Example: Cyclopia • 3 (trisomy) chromosomes of chromosome 13 -15 or 17 -18 What are some mutagenic factors and what effects do they have on 22

WARNING the following slide contains a disturbing image View at your own discretion What are some mutagenic factors and what effects do they have on 23

Cyclopia • Two eyes within one orbit • Proboscis-like appendage above the eye • Low-set or missing ears • Missing facial bones • Congenital heart disease • Do not survive What are some mutagenic factors and what effects do they have on 24

Chromosomal Mutations • 4 types of mutations – Deletion – Duplication – Inversion – Translocation What are some mutagenic factors and what effects do they have on 25

Chromosomal Mutation Deletion • Occurs when part of a chromosomes breaks off during mitosis/meiosis • Serious mutation that often causes death of the organism What are some mutagenic factors and what effects do they have on 26

Chromosome Mutation Duplication • Occurs when a section of a chromosomes is repeated • May cause genes to not function properly • Can also lead to developmental and physical disabilities What are some mutagenic factors and what effects do they have on 27

How could a mutated gene produce a shorter protein that produced by the normal gene? What are some mutagenic factors and what effects do they have on 28

Answer A frame shift or a point mutation may have changed one of the codons to a stop codon What are some mutagenic factors and what effects do they have on 29

Chromosomal mutation Inversion • Occurs when a section of a chromosome breaks off, changes direction, and recombines to the same chromosome • Usually no serious effects • Genes are still intact and present on correct chromosome What are some mutagenic factors and what effects do they have on 30

Chromosomal Mutation Translocation • Piece of chromosome breaks off one chromosome and combines with a different chromosome • Causes serious physical and developmental disabilities What are some mutagenic factors and what effects do they have on 31

Translocation • Results in miscarriage of zygote usually • Produce gametes with wrong number of chromosomes • Usually harmless but can cause cancers (leukemia), and infertility What are some mutagenic factors and what effects do they have on 32

Did you know… • Mutations can occur in all types of organisms…even the human race. • One mutation that is very unlikely to be seen is multiple toes and fingers. • Doctors usually remove extra digits at birth. What are some mutagenic factors and what effects do they have on 33

LEQ#5: What relationships exist between mutations and the potential appearance of new traits? What are some mutagenic factors and what effects do they have on 34

Vocabulary to Know: • • Germ line mutation Somatic Mutation Sterile Inherited Meiosis Beneficial mutation Lethal Mutation Silent mutation • • Turners syndrome Down syndrome Klinefelters syndrome Cystic fibrosis Cancer Gametes Harmful mutation Intron What are some mutagenic factors and what effects do they have on 35

Consequences of Mutations • Depend on the type of cell the DNA mutation occurs in • Can occur in two types of cells – Somatic (body cell) – Germ line (gametes: sperm/egg) What are some mutagenic factors and what effects do they have on 36

Somatic Mutation • Are NOT passed down to offspring • Causes: – Random natural causes – Environmental factors: radiation, x-rays, sunlight – Chemical: cigarettes, cleaners, pesticides • Often lead to cancer What are some mutagenic factors and what effects do they have on 37

Germ Line Mutations • Mutations can be passed down to offspring (inherited) • Usually occur during Meiosis – Type of cell division the produces gametes in sexually reproducing organisms • Mutations in germ line affect the phenotype of the offspring. • Many are so severe that offspring do not develop properly and die before they can reproduce or are sterile – Incapable of producing offspring What are some mutagenic factors and what effects do they have on 38

Appearance of new traits • Impact on phenotype of organism – Silent mutation – Harmful mutation – Lethal mutation – Beneficial mutation • Impact on offspring What are some mutagenic factors and what effects do they have on 39

Impact on Phenotype • Many gene mutations do not affect an organisms phenotype. • Mutation that does not affect the resulting protein is called a silent mutation. • Mutation that occurs on the noncoding region (intron) may not affect the encoded protein at all. – Segment of gene that does not code for an amino acid What are some mutagenic factors and what effects do they have on 40

Impact on Phenotype • Chromosomal mutations affect a lot of genes and tend to have a big effect on an organism • Mutation that alters a important protein and affects its function is called a harmful mutation What are some mutagenic factors and what effects do they have on 41

Klinefelters Syndrome • • • XXY (47 Chromosomes) Extra sex chromosome Sterile increase breast tissue, decrease in testosterone Greatly reduced male genitalia Some breast production Wide curvy hips No sperm production & no sex drive Sterile What are some mutagenic factors and what effects do they have on 42

Down Syndrome • Extra copy of chromosome 21 (47 chromosomes) • Broad short head • Malformed ears • Mental retardation • Protruding tongue when mouth is open • Impairment of cognitive and physical development What are some mutagenic factors and what effects do they have on 43

Turner’s syndrome • • • X 0 ( 45 Chromosomes) only one female sex chromosome Short stature Wide-spaced underdeveloped nipples Webbed neck Swelling of hands & feet low hairline Sterile What are some mutagenic factors and what effects do they have on 44

Lethal Mutation • Mutations that lead to the death of an organism are considered to be lethal mutations What are some mutagenic factors and what effects do they have on 45

Patau’s Syndrome • Trisomy chromosomes 13 -15 • Cleft lip and palate • Bone defects on skull • Large bulbous nose • Congenital heart disease • Majority die within a year What are some mutagenic factors and what effects do they have on 46

Edward’s Syndrome • Trisomy on chromosomes 17 -18 • Small head • Ears deformed • Cleft palate • Severe retardation • Majority die within a year What are some mutagenic factors and what effects do they have on 47

Impact on the Phenotype • A very small percentage of all mutations actually have a positive effect these are called beneficial mutations. • These mutations lead to new versions of proteins that help an organism and its future generations better adapt to changes in their environment. • Example: – Deletion of CCR 5 gene leads to HIV resistance – Found in European descent – Believe to be a result of survivors of the bubonic plague or small pox What are some mutagenic factors and what effects do they have on 48

Some genetic mutations are associated with increased risk for a particular disease. Tests exist for some of these genes. What might be the advantages and disadvantages of being tested What are some mutagenic factors and what effects do they have on 49

Answer • Advantage: – You would know what symptoms to look for – You would be able to prepare for treatment • Disadvantage: – There may be no cure for the disease – Simply having the gene may not mean that getting the disease is inevitable What are some mutagenic factors and what effects do they have on 50