MUTATION AND VARIATION

Bio 101 Notes

MUTATION AND VARIATION

CUT OBJECTIVE 26!!!

NON-MENDELIAN INHERITANCE

-Mendelian = Complete Dominance -Only the dominant allele’s protein is produced -When a yellow and purple parent produce a purple offspring -Not all traits are simply determined by a single dominant and a single recessive allele.-Incomplete Dominance (see Diana’s picture) -A little of each allele’s protein is produced.-Codominance -A lot of each allele’s protein is produced.-Polygenic - Multiple genes determine the trait -Eye color -Bell Peppers -Colon Cancer - Human needs to have mutations in about 7 different genes.-Sex-Linked Traits -Gene for trait is on portion of “X” chromosomes not matched by “Y”

COMPLEXITY

-Variable Expression: All cells in an organism have the same genes, but only some are used.-Muscle Cell -Pancreatic Cell

• Molecular “bookmarks” are put in each cell’s DNA to indicate which genes should be

active.

-Modifier Genes: Some genes can modify the effect of another gene.

-Albino: Gene stops production of pigment proteins

-Master Control Genes: Activate numerous genes to control complex tasks

-Environmental Effects: A cell’s surroundings can impact how genes function

-Diet and hormones

-Which is a bigger influence: Genetics or Environment? (Nature vs Nurture)

-Heterochromia: your eye has 2 distinct color

MUTATIONS

-Mutations produce new alleles (versions of genes)

-Mutation: DNA is altered

-“Big” Chromosomal Mutations - structured changes or irregular number (uncommon) -Base “Point” Mutation - common -Mutations in sperm and eggs can be passed on to future generations.-Causes of Mutations -Mistakes during DNA replication This study source was downloaded by 100000829878664 from CourseHero.com on 08-01-2022 02:17:58 GMT -05:00

https://www.coursehero.com/file/8146387/Bio-101-Class-Notes/

-Damage from external agents (mutagens) -Defenses Against Mutation -Mutation repair proteins -Effects of Mutations

-Primary Impact: No change (in protein or cell function)

-Less Frequent: Negative Impact

-Rare: Positive Impact

Day 6

1/24/2013

DEVELOPMENT

EXAM ON MONDAY AT 7PM!!!!

FRUIT FLIES

-“Fruit Fly” Drosophila Melanogaster -Easy to care for -Short generation time (7+ days) -Large numbers of offspring -Identifiable mutations -Fruit fly mutations -Different eye color, eye shape, wings, color. larva, etc.-Thomas Hunt Morgan (1866-1945) -Demonstrated that genes are located on chromosomes.-Sex-linked traits -Crossing-over between chromosomes.-Famous for his paper where he talks about genetics and evolution.-Linked Mendel’s principles of inheritance and Darwin’s theory of natural selection as a means for transforming species.-Fruit Fly Genome -A genome is all of the hereditary information found in an organism.

-# of Chromosomes: Fruit Flies 2N = 8, Humans 2N = 46

-# of Genes: Fruit Flies ~ 13,600, Humans ~ 23,000

-Fruit Fly Life Cycle -See Picture

-Meiosis: only happens to produce sperm and eggs, just for sexual reproduction.

-(2N -> 1N) -Meiosis has an E and Sex has an E

-Fertilization: (1N + 1N = 2N)

-Mitosis: a cell make a genetic copy (2N -> 2N)

-Excessive Mitosis: Cancer

GENES AND DEVELOPMENT

-See Diana’s Pictures -Master Control Genes -HOX Genes: organize head, thorax, abdomen This study source was downloaded by 100000829878664 from CourseHero.com on 08-01-2022 02:17:58 GMT -05:00

https://www.coursehero.com/file/8146387/Bio-101-Class-Notes/

-Different species have many similar genes -Myosin Protein - allows fruit flies muscles to work for flight -Different species have similar proteins -Kinase proteins necessary for mitosis -If different species have many similar genes, where do the differences come from?-Only a small part of DNA is genes, the rest is non-coding (“junk”) DNA -Transposons - non-coding DNA that can be copied and move around -Increased variation

NATURE VS NURTURE

-Genetics and the environment can impact phenotypes.-Partly both nature and nurture

-Molecules can impact DNA:

-Recall the “Bookmarks” -Epigenetics: chemicals attach themselves to chromosomes and change the way genes function.-Methyl added to bases represses genes -Molecules attach to histone proteins alter surrounding DNA activity -Possible Paradigm Switch: Inheritance = DNA + Chemicals? This study source was downloaded by 100000829878664 from CourseHero.com on 08-01-2022 02:17:58 GMT -05:00

https://www.coursehero.com/file/8146387/Bio-101-Class-Notes/