key concept mutations are changes in dna that may or may not affect phenotype
DESCRIPTION
KEY CONCEPT Mutations are changes in DNA that may or may not affect phenotype. Mutations. Caused by errors in Replication, transcription, cell division, or by external factors Germ-cell mutation – occurs in a gamete Does not affect the individual but may be passed on to offspring - PowerPoint PPT PresentationTRANSCRIPT
8.7 Mutations
KEY CONCEPT Mutations are changes in DNA that may or may not affect phenotype.
8.7 Mutations
MutationsCaused by errors in• Replication, transcription, cell division, or by external
factorsGerm-cell mutation – occurs in a gamete• Does not affect the individual but may be passed on to
offspringSomatic mutation – occurs in a body cell• Will affect the individual but are not passed on to
offspring
8.7 Mutations
Lethal Mutations
• Cause death, often before birth
8.7 Mutations
Gene Mutations
1. point mutation – substitutes, adds or deletes a single nucleotide
mutatedbase
8.7 Mutations
Gene Mutations2. Frame Shift Mutation • Deletion & addition point mutation cause the remaining
codons to be incorrectly grouped
8.7 Mutations
8.7 Mutations
Chromosome Mutations
1. Deletion – loss of a piece of a chromosome due to chromosomal breakage
2. Inversion – chromosomal segment breaks off and then reattaches in reverse order to the same chromosome
3. Translocation – chromosome piece breaks off and reattaches to another non-homologous chromosome
8.7 Mutations
8.7 Mutations
4. Nondisjunction – failure of homologous chromosomes to separate properly during meiosisTwo possible outcomes:
1. One gamete - an extra chromosome • when fertilized - 3 copies of chromosome • trisomy
2. One gamete - one less chromosome • when fertilized - 1 copy of chromosome • monosomy
8.7 Mutations
KEY CONCEPT A combination of methods is used to study human genetics.
7.4 Human Genetics and Pedigrees
13.1 Ecologists Study Relationships
Pedigree – family record that shows how a trait is inherited over several generations
7.4 Human Genetics and Pedigrees
8.7 Mutations
Pedigrees
Circles Girls
Squares Boys
Carrier – individual with one copy of a recessive allele• Usually do not express the trait but can pass it along to
offspring• ½ colored in
• Ex: Autosomal Hh
Sex-linked XHXh
7.4 Human Genetics and Pedigrees
8.7 Mutations7.4 Human Genetics and Pedigrees
8.7 Mutations
• Karyotypes can show changes in chromosomes.
– deletion of part of a chromosome or loss of a chromosome
– Some translocation changes in chromosomes– extra chromosomes or duplication of part of a
chromosome
7.4 Human Genetics and Pedigrees
8.7 Mutations
Detecting Human Genetic Disorders• Genetic screening – examination of a person’s genetic
makeup• Genetic counseling – medical guidance that informs
about possible problems that could affect their offspring
Prenatal testing• Amniocentesis – removes a small amount of amniotic
fluid between the 14th
and 16th week of pregnancy
7.4 Human Genetics and Pedigrees
8.7 Mutations
Chorionic villi sampling
• physician obtains a sample of the chorionic villi • tissue that grows between the mothers uterus and the
placenta, between the 8th and 10th week of pregnancy
7.4 Human Genetics and Pedigrees
13.1 Ecologists Study Relationships
Cancer
Tumor – abnormal group of cells that result from uncontrolled,
abnormal cell division
5.3 Regulation of Cell Cycle
8.7 Mutations
cancer cellbloodstream
normal cell
– Benign - tumors remain clustered and can be removed.– Malignant - uncontrolled dividing cells invade and
destroy healthy tissues elsewhere in the body
– Metastasize - spread of cancer cells beyond their original site
5.3 Regulation of Cell Cycle
8.7 Mutations
Kinds of Cancer – based on types of tissue that affect
• Carcinomas – grow in the skin and tissues that line organs. Ex: lung cancer & breast cancer
• Sarcomas – grow in bone and muscle tissue• Lymphomas – solid tumors that grow in the tissues that
form blood cells– Leukemia – tumors that form in blood-forming tissue –
over production of white blood cells
5.3 Regulation of Cell Cycle
8.7 Mutations
Causes of Cancer
• Carcinogen – substance that increases the risk of developing cancer Ex: tobacco, asbestos, X-rays, or UV rays from sun
• Mutagen – cause mutations to occur within a cell that leads to cancer
5.3 Regulation of Cell Cycle
8.7 Mutations
• Standard cancer treatments typically kill both cancerous and healthy cells.
5.3 Regulation of Cell Cycle
8.7 Mutations
Oncogenes – gene that causes cancer
• Proto-oncogene – normal gene that control cell’s growth. When mutated oncogene
• Tumor-suppressor gene – code for proteins to prevent uncontrolled cell division. When mutated cancer
5.3 Regulation of Cell Cycle
8.7 Mutations
Viruses & Cancer
• Viruses can stimulate uncontrolled cell division• Cause mutations in proto-oncogenes & tumor suppressor
genes
5.3 Regulation of Cell Cycle
8.7 Mutations
Cancer Prevention
• Diet high in fiber and low in fat• Fruits & vegetables are high in fiber• Vitamins & minerals: carotenoids, vitamins A, C, and E,
and calcium• Daily exercise• And lowering exposure to carcinogens (tobacco, UV rays)
5.3 Regulation of Cell Cycle
8.7 Mutations
Extra Credit:
• Millions of dollars are spent each year on cancer research.
• Contact an oncologist in a cancer treatment center.• Conduct an interview, prepare a paper, and create a
visual to show the new treatments that have been developed in the past 10 years
5.3 Regulation of Cell Cycle