Presentation on theme: "The Human Genome Karyotype Mapped out picture of chromosomes arranged in their homologous pairs. 46 chromosomes in human genome 23 pairs on karyotype."— Presentation transcript:
The Human Genome Karyotype Mapped out picture of chromosomes arranged in their homologous pairs. 46 chromosomes in human genome 23 pairs on karyotype
2 Types of Chromosomes Sex Chromosomes Determine individual’s gender/sex 2 out of 46 (1 pair) 23 rd pair is always sex pair Females: XX (2 X chromosomes) Males: XY (1 X and 1 Y chromosome) Autosomes Non-sex chromosomes Remaining 44 of 46 (22 pairs) Pairs numbered 1 through 22
Determining gender… Egg Cells-carry single X chromosome Sperm Cells-half carry single X chromosome, half carry single Y chromosome Who determines gender??? Mom or Dad?
Human Pedigrees Female Male Partner Brothers and Sisters
Autosomal Codominant Disorders Sickle Cell Disease-sickle shaped red blood cells, damage tissues, oxygen deficit, cause fatigue, more prone to infections (malaria resistance)
Sex-Linked Genes Genes located on the X or the Y sex chromosomes Some X-Linked: MD, melanoma, colorblindness, hemophilia Some Y-Linked: testis determining factor Males only have 1 X chromosome will express phenotype for an X-linked gene from 1 allele (either dominant or recessive) Females have 2 so they can be dominant, carriers, or recessive.
X-Linked Recessive Disorders Males only need to inherit 1 recessive allele to express the disorder more common in males Females need to inherit 2 recessive copies of gene to express disorder Colorblindness-inability to distinguish certain colors Hemophilia-abnormal blood clotting excessive external/internal bleeding Duchenne Muscular Dystrophy-progressive weakening and loss of skeletal muscle
Father (normal vision) Colorblind Normal vision Mother (carrier) Daughter (normal vision) Son (normal vision) Daughter (carrier) Son (colorblind) Male Female Figure 14-13 Colorblindness = carried only on the X chromosome (never the Y) What are the genotypes and phenotypes of the offspring according to gender?
Father (normal vision) Colorblind Normal vision Mother (carrier) Daughter (normal vision) Son (normal vision) Daughter (carrier) Son (colorblind) Male Female Figure 14-13 Colorblindness
Genetic Problem- Sex- Linked A woman who is a carrier for hemophilia mates with a man who has hemophilia. Identify the genotypic and phenotypic ratios ACCORDING TO GENDER for the offspring
Nondisjunction Homologous chromosomes fail to separate in Anaphase I of Meiosis Results in gametes with abnormal chromosome numbers disorders
Chromosomal Disorders Down Syndrome-Trisomy 21 (3 copies of chromosome #21, instead of the normal 2); mild to severe mental retardation, birth defects Turner’s Syndrome-female with only 1 X chromosome (genotype=XO); no sex organs sterile Klinefelter’s Syndrome-male with extra X chromosome (genotype=XXY); sterile