Heredity-transmission of traits from 1 generation to the next Genetics-study of heredity & variation Genes-segments

1. Heredity-transmission of traits from 1 generation to the next • Genetics-study of heredity & variation • Genes-segments of DNA • Gemetes-reproductive cells (sperm, egg) • These are haploid (n) • Somatic cells-body cells-diploid (2n)

2. Fusion of gametes = zygote • Locus-location of a gene on a chromosome • Genome-the complete complement of an organisms’ genes

3. Karyotype-a display of all pairs of homologous chromosomes in a cell, arranged by size & shape • Homologous chromosomes-those that carry the genes that control the same traits • Autosomes- non-sex chromosomes

4. Meiosis-production of gametes • Is preceded by DNA replication • Result is 4 haploid daughter cells • Meiosis I – homologous chromosomes separate • Crossing over occurs

5. Crossing over • Prophase I • Synapsis-joining of homologous chromosomes along their length • This is called a tetrad • Chiasmata-place where crossing over occurs (where homologous chromosomes overlap)

6. Meiosis II-sister chromatids separate • Synapsis & crossing over do not occur during mitosis • Tetrads line up in metaphase I instead of just sister chromatids

7. If a heart cell of an animal has 36 chromosomes how many chromosomes does its sperm cell have? • Independent assortment @ Metaphase I

8. Alterations of generations • Plants & some algae • Haploid & diploid life cycle • Diploid stage- sporophyte (meiosis makes haploid spores/that divide via mitosis to make a gametophyte

9. Haploid stage- gametophyte (makes haploid gametes via mitosis & then fertilization occurs making diploid zygote) • **a multicellular haploid stage occurs (this does not occur in animals)

10. Ch14 • True-breeding-plants that self-pollinate & so all offspring are of the same type • Hybridization- Crossing 2 true-breeding plants • The true breeding plants are the (P) parental generation

11. Their offspring are the F1 generation • If the F1 are X’ed then an F2 generation results • Alleles-diff versions of a gene • Recessive • Dominant-fully expressed

12. Homozygous-2 of the same alleles • Heterozygous-2 diff alleles • Phenotype-expressed trait • Genotype-the genetic makeup • Testcross-X’ing recess indiv w/an indiv showing the dom phenotype to find out if the organism is homo, or hetero

13. Monohybrid cross-cross studying only 1 characteristic • Dihybrid-cross to study 2 char • A 3:1 ratio suggests that both parents are heterozygous

14. The phenotypic ratio of a typical F2 generation w/Mendelian inheritance is 9:3:3:1

15. An organism with the genotype SsVv can have what possible gametes? • SV • Sv • sV • sv

16. Codominance-2 alleles are dominant & affect phenotype in 2 diff but = ways (blood type) • Incomplete dominance-when the F1 hybrids have a phenotype in b/w both parents usually a 1:2:1 ratio • Multiple alleles- many diff alleles for a trait (Blood type)

17. Pleiotropy- makes it have phenotypic effects • epistasis- a gene at 1 locus affects a gene at another locus • Polygenic inheritance-2 or more genes have an additive effect on a single character (height, skin)

18. Pedigree-family tree tracking a gene through generations

20. Ch15 • Chromosome theory of inheritance: • Genes have specific locations on chromosomes • Sex-linked genes- genes on the sex chromosomes (X or Y)

21. Linked genes-genes on the same chromosome that tend to be inherited together • Recombination-the production of offspring that have a new combination of genes than those of the parents

22. Parental types-receive non-recombinant genes • Recombinants-get the new combination of genes • Genetic map-ordered list of genes & their loci on a chromo • Linkage map-based on recombination freq’s

23. A freq of 50% indication that the genes are on diff chromo’s • Sex-linked traits are passed on to sons from their mom • Fathers pass on sex-linked traits to daughters but not sons • Males are Hemizygous

25. Cytogenetic map-A map of a chromosome that includes the positions of genes relative to visible chromosomal features, such as stained bands • Barr body-inactivated X chromosome • Nondisjunction-when homologous chromosomes do not separate in Meiosis I or sister chromatids do not separate in Meiosis II

27. Aneuploidy-offspring w/incorrect chormo # • Polyploidy-having more than 2 complete sets of chromo’s • Monosomic • Trisomic

28. Deletion-a piece of the chromo is lost, so the chromo is missing genes • Duplication-the fragment that broke off (above) attaches to its sister chromatid • Inversion-fragment breaks off, & reattached to original position but inverted

29. Translocation-the fragment joins a nonhomologous chromosome • Down’s syndroms-trisomy 21 • Klinefelters syndrome-XXY • Turners syndrome-X

30. Two true-breeding stocks of pea plants are crossed. One parent has red, axial flowers and the other has white, terminal flowers; all F1 individuals have red, axial flowers. If 1,000 F2 offspring resulted from the cross, approximately how many of them would you expect to have red, terminal flowers? (Assume independent assortment.)

31. Describe how a germ cell’s complement of the chromosomes is halved in the formation of gametes. Describe how reduction & rearrangement are accomplished in meiosis.

32. Choose one organism or group of organisms that reproduce sexually. Describe the mode of sexual reproduction in that organism and explain the advantages to the organism of sexual reproduction.

33. Choose an organism that reproduces asexually. Describe the mode of asexual reproduction in that organism and explain the advantages to the organism of asexual reproduction.

34. Several human disorders occur as a result of defects in the meiotic process. Identify one such chromosomal abnormality, what effects does is have on the phenotype of people with the disorder? Describe how this abnormality could result form a defect in meiosis.