PC 705 Module 1 Exam - Stress and Genetics

PC 705 Module 1 Exam - Stress and Genetics Genotype The exact gene allele composition for a single gene trait Phenotype the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment. Ploidy Number of chromosomes present in nucleus of cell in metaphase at mitosis Haploid 1N—One complete set of chromosomes (23) Ex: gametes Diploid 2N—-both pairs of chromosomes (23 pairs or 46 individual) Polyploidy Extra chromosomes in every pair. For example 3 chromosomes in every pair would mean 69 total chromosomes. Normal somatic cell characteristics include: *Diploid *46 chromosomes (23 pairs) *euploid (normal) *44 somatic & 2 sex Aneuploid More or fewer chromosomes but does not mean for every chromosome pair. Mature reproductive cells have how many chromosomes? 23-haploid Karotype Arrangement of chromosomes during metaphase in mitosis Dominant genes need one or two alleles to be expressed? One — Ex: Aa What are some examples of autosomal dominant genes? Blood types A & B Huntington disease Widows peak Type 2 diabetes Neurofibromatosis Long QT syndrome Polydactyl Free earlobes PTC Retinoblastoma Autosomal needs how many alleles to be expressed? Two—-Ex: aa What are some examples of autosomal recessive genes? Sickle cell anemia Albinism Cystic fibrosis Ataxia PKU tachysachs Sex linked recessive traits most affect which sex chromosome? X Can boys be carriers for x linked recessive disorders? No. They only have one X chromosome, so if inherited it will be expressed. For x linked recessive disorders, how are women affected? They can be carriers or affected. If they inherit both affected alleles they are affected. If they only inherit one affected allele, they will be a carrier. X linked recessive disorders are recessive or dominant in females? Recessive. They have two X's, so the normal (unaffected allele) is dominant. X linked recessive disorders are recessive or dominant in males? Dominant. They only have one X chromosome so if they inherit one affected allele, the disease is expressed. How are x linked recessive disorders passed from mother and father? Mothers pass to sons and daughters (donating an X) Fathers pass to only daughters (giving an X to girls and a Y to sons) If a girl is homozygous x linked recessive affected, what most likely will result? Early miscarriage Homozyogous means Two exact alleles—Ex: AA or aa What does heterozygous mean? Two different alleles—ex: Aa Alleles are variations of what? Genes Spermatogenesis use a diploid germ cell to form 4 haploid spermatid Spermatogenesis begins when? At or just before puberty Is spermatogenesis continuous? Yes Prophase 1 in spermatogenesis takes how long? Hours to days Are all 4 haploid sperm created from the diploid germ cell able to fertilize an ovum? Yes Spermocytes are dormant where and until when? Testes until puberty Which determines gender? Sperm or Ovum? Sperm—donates either an x or y When does spermatogenesis stop? It doesn't, it's continuous until death. Oogenesis uses a diploid germ cell to form 1 mature ovum capable of being fertilized and potentially 3 polar bodies In oogenesis, prophase 1 can take how long? Years Is oogenesis continuous? No, it is cyclic. When does oogenesis begin? In fetal life When does oogenesis stop?