Chromosomes and Inheritance

1. Chromosomes and Inheritance

2. Autosomes vs. sex chromosomes Autosomes = the pairs of chromosomes that are the same in males and females In humans, these are chromosomes # 1 - # 22

3. sex chromosomes = differ between males and females of a species: differ physically and in the genes they carry In humans, chromosome # 23

4. female x x xx & male xy y x & sex determination in humans: female gives: male gives:

5. Alleles alleles are different forms of a given gene ex. gene = tongue rolling tongue roller vs. non-roller

6. the alleles from mom and dad may be the same, may be different chromosome # 14 tongue rolling gene from mom tongue rolling gene from dad

7. Each person carries 2 copies of each gene (on their autosomes) Genotype = the gene forms, or alleles someone carries

8. Genotypes RR- if they carry the same allele on both chromosomes -> HOMOZYGOUS Rr- if they carry different alleles -> HETEROZYGOUS

9. Phenotype = the physical or physiological expression of those alleles

10. alleles can have different relationships to each other dominant --- recessive 1. a dominant allele, when found in the heterozygous condition, overrides the recessive allele Rr -> will result in a tongue roller

11. roller roller non-roller GENOTYPE PHENOTYPE RR = homozygous dominant Rr = heterozygous rr = homozygous recessive

12. 2. incomplete dominance

13. 3. multiple alleles with codominance ex. blood type

14. ex. a person born with 6 fingers Genetic Disorders 1. genetic abnormality- an uncommon version of a trait

15. 2. genetic disorder- an inherited condition that will result in mild to severe health problems. ex. cystic fibrosis

16. 3. syndrome- a set of symptoms that characterize a given disorder

17. Autosomal dominant inheritance = trait will typically appear in every generation HH or Hh Ex. Huntington’s disorder (nervous system)- typically fatal in 40’s or 50’s Why does gene stay in population? its effects occur post-reproduction

18. Autosomal recessive inheritance- trait (disorder) shows up less often in the population because the trait can be masked by the dominant allele Ex. galactosemia: gg lactose galactose glucose-1-phosphate glucose X results in a buildup of galactose in blood… damage to eyes, liver, brain

19. male female x-linked recessive traits- gene is only found on the x chromosome- not the Y! xAxA xAxa xaxa xAy xay 33.3% 50%

22. Hemophilia in Royal Families in Europe I-1 = King George III III-1 and III-2 = Prince Albert and Queen Victoria IV-5 and IV-6 = Alice of Hesse and Ludwig IV of Hesse V-13 and V-14 = Alix and Nicholas II (Tsar of Russia) VI-16 = Alexei VIII-1 = Prince Charles

24. Changes in Chromosome Number aneuploidy= the condition of having less than or more than the normal diploid number of chromosomes polyploidy- condition of having 3 or more entire sets of chromosomes (lethal in humans)

25. Down syndrome (trisomy 21): The result of an extra copy of chromosome 21. Down syndrome affects 1:700 children and alters the child's phenotype either moderately or severely.

27. cause of aneuploidy = NONDISJUNCTION Failure of paired chromosomes to disjoin (separate) during cell division so that both chromosomes go to one daughter cell and none to the other.

28. Patau syndrome (trisomy 13): serious eye, brain, circulatory defects as well as cleft palate. 1:5000 live births. Children rarely live more than a few months.