blood banking

• Humans are diploid organisms, meaning that each somatic cells contain two copies of each chromosome, one from each parent
• The somatic cells contain 46 chromosomes
• Karyotype – displays all the chromosomes in a cell obtained from a metaphase spread
• Germs cells (eggs and sperm cells) – are produced by meiosis and contain a haploid number of chromosomes (23) that consists of one copy each of the autosomes and one sex chromosome
• Independent assortment – each chromosome in a pair is randomly sorted into a

  daughter cell. There is no linkage of chromosomes when they segregate during

  meiosis
• Genetic materia- Substance that store information about structure, function

  and development of various characteristics of living

  organisms
• The genetic material for all living organisms is composed of

  DNA (deoxyribonucleic acid)
• gene- a segment of a DNA molecule that contains the information required for the

  synthesis of a functional biological product whether protein or RNA
• Reside at specific locations known as locus (singular) or loci (plural), on a

  particular chromosome
• Allele – the form of a gene at a given locus; each locus has two alleles (one

  per chromosome)
• Homozygous – refers to the two alleles being identical
• Heterozygous – refers to the two alleles having a different nucleotide

  sequence, which may be caused by mutations.
• Phenotype – the observation traits of the individual produced by the

  interaction of the genes and the environment
• Genotype – the genetic composition of the individual
• heritability- the capability to inherit a trait from a parent
• Genetic composition of 100% - indicates no

  influence of the environment on the inheritance of the

  phenotype of the individual.
• Environmental composition- indicates that the

  major determinant of the phenotype is environmental rather

  than genetic
• Dominant trait – one that manifests itself even when an allele is in a

  heterozygous state
• codominant trait – both alleles in a heterozygous pair are expressed

  (ex. Blood group antigens)
• Recessive trait – one that manifests only when the gene is in a

  homozygous state.
• Sex-linked trait – when the mutant allele is located on the X

  chromosome, the disease will generally be expressed in males

  (because males have one X chromosome)
• penetrance- refers to an individual expressing a phenotype when

  inheriting a particular mutated allele.
• Variable expressivity- refers to the severity of the expressed phenotype caused by

  a mutated allele.
• Autosomal dominant inheritance - An affected individual has an affected parent unless the affected is

  expressing a new mutation.
• Achondroplasia (dwarfism) – caused by mutation in fibroblast growth factor receptor
• Huntington disease type 2 – caused by a triplet repeat expansion in the HTT

  gene
• Hypercholesterolemia – caused by a mutation in the low-density lipoprotein

  receptor
• Marfan syndrome – caused by a mutation in the fibrous protein fibrilin
• Polycystic Kidney disease – caused by mutations in a number of membrane

  proteins
• Tuberous sclerosis – caused by new mutations in the TSC1 and TSC2 genes
• Autosomal recessive inheritance- Both sexes are affected equally

  The transmission of the trait must occur from both parents
• Albinism – affects 1 in 20,000 live births and is caused by a loss of

  melanocyte tyrosinase
• Cystic fibrosis – caused by a mutation in the CF transmembrane

  conductance regulator protein
• Phenylketonuria – caused by a mutation in phenylalanine hydroxylase
• Hemochromatosis – iron storage disease caused by a variety of

  mutations involved in iron absorption and transport
• Sickle cell disease – E6V amino acid change in the 𝛽 chain of globin
• hemizygous - a person who has only one copy of a

  gene rather than the usual two copies
• X-linked recessive disorders - There is no male-to-male transmission

  Females are usually asymptomatic
• Hemophilia A – caused by a mutation in the factor VIII

  gene
• Duchenne muscular dystrophy – caused by large

  deletions in the DMD gene