Chapter 11 Intro to Genetics

Question of the day How many hybrids are there on the earth? All humans, plants, animals, even some cars are hybirds - there is no such thing as “pure bred”

11-1 Father Gregor Mendel Who was he? Austrian monk, who taught Biology and grew plants for the monastery. Originally from Czech Republic in 1822 Worked with pea plants

Genetics Why is what Mendel studied important? Studied the foundation of genetics (1st time anyone did) Genetics - scientific study of heredity What does heredity mean? Inheirit DNA from prior generations

What is Geneology? The study of your ancestors and family tree Often determined by your name Where your ancestors lived Parents occupation or livelihood Ethnic background Etc

What are genes? Genes are your chromosomes How many do you have? You have 25,000 -35,000 genes What do they do? Carry info to determine your traits

What are traits? Traits are the physical features passed down to you from parents, grandparents, etc. What are some good examples? Eye color Hair Color & texture Widows peak Skin Color Bone features (dimples, pronounced chin, etc.)

Genes & Dominance GM studied specific charac. passed onto generations called traits Parents (P) pass down traits to offspring (F1) Why is it called F1? F1 = 1st filial (latin for son/daughter)

Parents & Characteristics All Parents (P) are TRUE- BREEDING (if self fertilized would produce identical F1) Two parents w/ diff. traits produce cross (HYBRID) F1 Pass down GENES (chem factors for traits) Diff. kinds/types of genes are ALLELES Some alleles are DOMINANT over others

Future Generations Called F2 and so on When F1 reproduces alleles SEGREGATE or pull apart Then GAMETES form (sex cells for reproduction)

11-2 Punnett Squares P.S. - The outcome diagram for offspring Can predict F1, F2… from P cross Takes alleles and crosses them Shows the PROBABILITY of genetic outcomes

Phenotype & Genotype Organism with same alleles HETEROZYGOUS - Organism with diff. alleles PHENOTYPE - physical characterist. GENOTYPE - genetic makeup All dominant alleles will show phenotype

11-3 Exploring Mendel’s Genetics INDEPENDENT ASSORTMENT - Parent Alleles will separate independently and then recombine in offspring One-Factor Cross - tracking 1 allele Two-Factor Cross - tracking 2 alleles

Summary of Mendel’s Principles Individuals inherit genes, passed down from parents If 2 forms of a gene exist, 1 is dominant other is recessive Parents have 2 copies of each gene, only pass 1 to offspring Alleles segregate independently

Different Types of Dominance/Recession Some traits are controlled by multiple alleles that aren’t dominant or recessive Incomplete Dominance - where heterozygous phenotype ends up in between two dominant phenotypes

Codominance Two or more alleles contribute to one combined phenotype Example Horses Roan Coat - made up of brown & gray hair looks reddish

Multiple Alleles Genes that have >2 alleles for a trait Combine to have multiple dominant phenotypes Examples - Rabbit coat colors & blood types

Polygenic Traits Traits controlled by 2 or more genes “Having many genes” Example - Human skin color is controlled by 4 different genes Lots of variations

11-4 Meiosis Just like Mitosis only with 2 rounds of it Have HOMOLOGOUS pairs - 2 sets of chromosomes (1 from each parent) Homologous pairs are DIPLOID - 2 sets of chromosomes Some reproducing organisms are HAPLOID 1 set of chromsomes

Phases of Meiosis A form of gamete  (sex cells, not regular cells) Two cycles of mitosis Called MEIOSIS I & II Cuts all Diploid chromosomes in 1/2 End up with 4 daughter cells

Meiosis I Interphase& Prophase I - Pairs of chromosomes come together form TETRAD Sometimes in tetrad, chromosomes get tangled up (CROSS-OVER) & exchange genetic info Metaphase - Chromosomes lineup Anaphase - Get separated by spindles & pull homologous cells away Telophase&Cytokinesis -  cytoplasm, nuclear mem. (2 daughter cells)

Meiosis I Picture

Meiosis II From Meiosis I have 2 haploid daughter cells (Prophase II) Metaphase II- Chromosomes lineup and separate on spindles (like mitosis) Anaphase II - Chromatids get pulled apart Telophase II & Cytokinesis -  nuclear mem. & cytoplasm End up with 4 daughter cells

Gamete Formation Males make 4 sperm cells Females make 1 egg & 3 polar bodies Only cells in human body that undergo meiosis

Differences Between Meiosis & Mitosis 4 Daughter Cells Gametes (Sex Cells) 2 Cycles of Mitosis Only 1/2 time Interphase Diploid & Haploid Chromosomes Tetrads Mitosis 2 Daughter Cells All cells except Gametes 1 Cycle only Interphase each time Diploid Only No Tetrads

11-5 Gene Linkage All alleles occur are on same gene in every human Some come together and are”linked” These genes can be tracked or mapped Gene Map - locations of certain alleles on genes