* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Chapter 12
Heritability of IQ wikipedia , lookup
Gene therapy wikipedia , lookup
Vectors in gene therapy wikipedia , lookup
Behavioural genetics wikipedia , lookup
Genetic drift wikipedia , lookup
Skewed X-inactivation wikipedia , lookup
Y chromosome wikipedia , lookup
Public health genomics wikipedia , lookup
Nutriepigenomics wikipedia , lookup
Genetic engineering wikipedia , lookup
Gene expression programming wikipedia , lookup
Oncogenomics wikipedia , lookup
Genome evolution wikipedia , lookup
Ridge (biology) wikipedia , lookup
Site-specific recombinase technology wikipedia , lookup
Population genetics wikipedia , lookup
Polycomb Group Proteins and Cancer wikipedia , lookup
Point mutation wikipedia , lookup
Artificial gene synthesis wikipedia , lookup
History of genetic engineering wikipedia , lookup
Minimal genome wikipedia , lookup
Dominance (genetics) wikipedia , lookup
Gene expression profiling wikipedia , lookup
Biology and consumer behaviour wikipedia , lookup
Genomic imprinting wikipedia , lookup
Epigenetics of human development wikipedia , lookup
X-inactivation wikipedia , lookup
Quantitative trait locus wikipedia , lookup
Genome (book) wikipedia , lookup
Chapter 12 Mutations, Xs, and Inheritance Mutations= changes in organisms DNA • Beneficial- lead to adaptations and aid evolution of a species • Harmful- the worst are lethal Types of Mutations 1.cellular mutations; a. germ cell mutation-change is in the gametes so it affects the offspring and not the parent organism b. somatic cell mutation-change is in an organism’s body cells will affect the organism but not the offspring ex; certain types of skin cancer, leukemia Chromosome mutations 1. Deletion- loss of part of X so missing genes and lack info 2. Inversion- one X breaks off a part and attaches in a reverse pattern 3. Translocation- X part breaks off and reattaches to a non-homologous X 4. Nondisjunction- Xs do NOT separate during anaphase of meiosis so one gamete gets too many Xs and gets too few Gene mutations(DNA---mRNA---aa---protein) point mutation- if only 1 base is affected 1. 2. 3. – Substitution Insertion Deletion #2 and #3 cause a change in the codon sequencecalled frameshifts Ex. THE CAT ATE THE RAT TTH ECA TAT ETH ERA T TEC ATA TET HER AT Genetics Traits 1. Single allele traits; a. Dominant allele Ex- Huntington’s Disease -HH or Hh will develop disorder -hh is normal -genetic marker used to ID b. Recessive allele -Heterozygous will give a carrier Ex 1- cystic fibrosis FF- normal Ff- carrier ff- normal Ex 2- sickle cell anemia AA- normal Aa- carrier aa- diseased Genetic researcher Thomas Morgan • Worked with fruit flies, Drosophila melanogster • Why fruit flies? 1. chromo. # = 8 (4 pairs) 2. Reproduce quickly 3. Males and females look differentt • Observations 1. males not like females 2. females had 2 XX and males had 1 X and 1Y 3. called this the sex determining pair 4. other 3 prs. alike in both sexes (autosomes) 5. Had either red or white eyes Morgan’s experiment with eye color • Took a male with white eyes and crossed it with a red eyed female. • Result was that ALL offspring had RED eyes!!!(F1) • Crossed 2 offspring together and got 3 Red eyed:1 white eyed; however ALL white eyed flies were males this time!!! • Why did that happen???? The Answer • Sometimes a gene appears only on the X or Y chromosome • These genes are called sex linked genes • Ex-Drosophila eye color, 2 possible alleles red (R) or white (r) • Allele only on the X chromo. • Genotypes= X R X R or X R Xr = red eyed females XrXr = white eyed females XRY = red eyed males XrY = white eyedmales Morgan’s 2nd Experiment • Hypothesized that genes that are inherited together are found on the same chromosome • Studied body color (GRAY vs. black) and wing length (LONG vs. short) • Crossed GGLL x ggll • What do you think he got??? Answer to GGLL x ggll • In the F1 all were GgLl (GRAY, LONG wings) • Morgan then crossed GgLl x GgLl • Results were 3 GRAY, LONG :1 black, short • Expected 9:3:3:1, instead results are always 3:1 for two characteristics • So Morgan concluded that these were “Linked Genes” Linked Genes • If known linked genes do NOT follow a predicted pattern they may have crossed over during meiosis • Ex.- pigmentation of human eye, hair, and skin color • Chromosome maps• Determine how far apart genes are on a chromosome • Geneticists use frequency • (%) of cross-overs in offspring to determine distance between genes • called map unit • Rule; for every 1% of crossovers the genes are 1 map unit apart (p.224) Chromosome Mapping • Geneticists use frequency(%) of cross-overs in offspring to determine distance between genes • called map unit • Rule; for every 1% of crossovers the genes are 1 map unit apart (p.224) 12-2 Pedigrees • used to study the inheritance of a trait through many generations • patterns of phenotypes can be followed using a chart Genetics Traits 2. X-linked Traits Allele on X chromosome • 2 needed for female phenotype • 1 allele for male phenotype • Ex- color blindness, hemophilia and Duchenne MD 3. Sex Influenced Traits • Phenotype affected by sex hormones • Ex- Baldness • BB is bald in male and female • Bb is bald only when testosterone present • bb- no baldness Genetic Traits 4. Multiple Allele Traits • Determined by three or more alleles • Ex- ABO blood type • Alleles- A and B (codominant) • O recessive 4 Phenotypes : Possible genotypes Type O OO Type A AO, AA Type B BO, BB Type AB AB Genetic Traits • 5. Polygenic Traits Controlled by 2 or more genes Ex- melanin amounts In Hair, skin, eye color Genotypes- AABBCC- darkest AaBbCc- lt brown aabbcc- lightest Genetic Testing • Before a fetus is born A. Amniocentesis- takes sample of amniotic fluid. - can only be done week 14-16 B. Chorionic villi- taken from chorionic villi - can only be done week 8-10 • Both require a karyotype be done after cells are samples. Genetic Diseases and Counseling • Refer to page 246-247 • http://www.youtube.com/watch?v=goEZ7f eoZVk Gene Therapy • Gene Therapy – a technique that replaces a defective gene with a healthy gene. -has been used to treat cystic fibrosis • 2 types of gene therapy 1. somatic cell- body cells are changed 2. germ cell- changes to egg and sperm