3 Think about it: What happens if our DNA gets messed up?
4 Cells sometimes make mistakes when copying their own DNA Cells sometimes make mistakes when copying their own DNA. These mistakes are called mutations. Mutations are changes in the genetic material.
5 Mutations that produce changes in a single gene are known as gene mutations. Mutations that produce changes in whole chromosomes are known as chromosomal mutations.
6 If a nucleotide is added or deleted, the bases are still read in groups of three, but now those groupings are shifted for every codon that follows. This is known as a frameshift mutation.
7 Gene mutations involving changes in one or a few nucleotides are known as point mutations. The three types of point mutations are substitutions, insertions, and deletions.
8 A small change in the DNA of a single gene affects the structure of a protein, causing a serious genetic disorder. (i.e. Cystic fibrosis, sickle cell disease)
9 Mutations that cause dramatic changes in protein structure are often harmful because the defective proteins disrupt normal life activities for the individual.
10 Genetic Mutations: Your Name Copy the chart below.Write your name in the first box.Put a box around each codon.Fill in the rest of the start by doing the mutation.Put a box around each codon after the mutation.Name:E N R I Q U EGA R Z APoint(add a base into the sequence)E N R I Q U EGA R Z KDeletion (take a base away)Insertion(add a base)
11 Name:E N R I Q U EGA R Z APoint(add a base into the sequence)E N R I Q U EGA R Z KDeletion (take a base away)E N R I U E GA R Z KInsertion(add a base)E X N R I U E GA R Z K
12 Think-Pair-ShareWhich would more likely have a bigger effect on an organism, a point mutation or frameshift mutation? Why?
13 Sickle Cell AnemiaThese are the sickle-shaped blood cells of someone with sickle cell anemia. Sickle cell anemia is the result of a point mutation, a change in just one nucleotide in the gene for hemoglobin. This mutation causes the hemoglobin in red blood cells to distort to a sickle shape when deoxygenated. The sickle-shaped blood cells clog in the capillaries, cutting off circulation. Having two copies of the mutated genes cause sickle cell anemia, but having just one copy does not, and can actually protect against malaria - an example of how mutations are sometimes beneficial.
14 Color BlindnessMost forms are caused by a point mutation on the X chromosome.What number do you see? A color blind person won’t see anything. A color deficient person may see the number 35
15 AchondroplasiaThis is the most common form of dwarfism. It is caused by a substitution mutation for the gene that codes for bone growth.
16 Genes located close together on the same chromosomes are linked, meaning that they tend to be inherited together. Genes located on the sex chromosomes are said to be sex-linked genes. The X chromosome contains more information than the Y chromosome.
17 Males have just one X chromosome Males have just one X chromosome. All X-linked alleles are expressed in males.
18 The 4 kinds of chromosomal mutations are: deletions, duplications, inversions, and translocations.
19 Polyploidy is a condition in which an organism has extra sets of chromosomes.
20 Trisomy occurs when someone is born with three copies of a chromosome Trisomy occurs when someone is born with three copies of a chromosome. Down Syndrome is the most common form of trisomy. In Down Syndrome, chromosome 21 is tripled.
21 Nondisjunction occurs when homologous chromosomes do not separate Nondisjunction occurs when homologous chromosomes do not separate. The result may be abnormal numbers of chromosomes in the gametes. Nondisjunction is the most common error in meiosis.
22 Genetic tests are now available for hundreds of disorders making it possible to determine whether prospective parents risk passing such alleles to their children. DNA testing can pinpoint the exact genetic basis of a disorder making it possible to develop more effective treatment for individuals affected by genetic disease.
23 Beneficial mutations may produce proteins with new or altered activities that can be useful to organisms in different or changing environments.