Pedigree Charts The family tree of genetics Pedigree

Pedigree Charts The family tree of genetics

Pedigree Charts I II III

What is a Pedigree? A pedigree is a chart of the genetic history of family over several generations. Scientists or a genetic counselor would find out about your family history and make this chart to analyze.

Constructing a Pedigree Female Male

Connecting Pedigree Symbols Examples of connected symbols: Married Couple Siblings

Example What does a pedigree chart look like?

Symbols in a Pedigree Chart Affected Carrier Deceased or

Interpreting a Pedigree Chart 1. Determine if the pedigree chart shows an autosomal or X-linked disease. If most of the males in the pedigree are affected the disorder is X-linked If it is a 50/50 ratio between men and women the disorder is autosomal.

Example of Pedigree Charts Is it Autosomal or X-linked?

Answer Autosomal

Interpreting a Pedigree Chart 2. Determine whether the disorder is dominant or recessive. If the disorder is dominant, one of the parents must have the disorder. If the disorder is recessive, neither parent has to have the disorder because they can be heterozygous.

Example of Pedigree Charts Dominant or Recessive?

Answer Dominant

Example of Pedigree Charts Dominant or Recessive?

Answer Recessive

Pedigree Chart

Human Genetics

Karyotype

Karyotyping A karyotype is an ordered display of an individual’s chromosome. Scientist take a picture of the chromosomes during metaphase. Each chromosome is paired with its homologue. Is used to detect abnormalities.

Chromosome Number Different # for Homologous different species Chromosomes Full set = 2 N=Diploid are the sets of N= Haploid each pair # pairs 1 pair from mother 1 pair from father Humans= 23 pairs or 46 total

Autosomes & Sex Chromosomes Autosomes = # 122 for all traits except sex Sex chromosomes= Pair # 23 XX(female) or XY(male)

Down Syndrome (AKA Trisomy 21)

Errors in Cell Division Nondisjunction is the failure of chromosomes to separate correctly (in meiosis I)

Errors in cell division Nondisjunction causes: 1. A gamete with an extra chromosome (n+1) Trisomy 2. A gamete missing a chromosome (n-1) Monosomy

Klinefelter’s = XXY

Multiple Alleles More than one type of allele for a trait Example: Blood Type TYPES: A B AB O I AI A, I Ai B B B I I , I i I AI B ii

Inherited Human Genetic Disorders Cystic Fibrosis Caused by a recessive allele Missing protein causes mucus build up in places like the lungs Most common among Caucasians

Cystic Fibrosis

Inherited Human Genetic Disorders Sickle Cell Anemia Caused by a co-dominant allele Altered protein changes the shape of red blood cells Most common among African Americans Heterozygous condition is resistant to malaria

Sickle Cell Anemia

Inherited Human Genetic Disorders Tay-Sachs Caused by a recessive allele Missing enzyme causes lipid build up in the brain (death by age 4) Most common among eastern European Jewish population

Tay-Sachs

Inherited Human Genetic Disorders Huntington’s Disease Caused by a dominant allele Late-onset of symptoms (age 40) result in the deterioration of nervous system

Huntington’s Disease

Inherited Human Genetic Disorders Phenylketonuria (PKU) Caused by a recessive allele Missing enzyme prevents the break down of phenylalanine (can cause brain damage) If caught early, an altered diet can prevent the damage

PKU

Karyotyping

Genetic Disorders (Chromosome Number) Down Syndrome Trisomy 21(3 copies of chrom. 21) Most common serious birth defect in the US Syndrome includes characteristic facial features, short stature, heart defects, and intellectual disabilities

Genetic Disorders (Chromosome Number) Kleinfelter’s Syndrome XXY Have abnormally small testes; are sterile; some feminine secondary sex characteristics; normal intelligence

Genetic Disorders (Chromosome Number) Extra Y XYY No obvious differences, usually tall

Genetic Disorders (Chromosome Number) Metafemales XXX Limited fertility, possible intellectual disability

Genetic Disorders (Chromosome Number) Turner Syndrome XO Is the only viable monosomy Short stature; fail to develop secondary sex characteristics; internal sex organs do not mature making the sterile

Other terms to know: Restriction enzymes – enzymes used to cut DNA at certain point Recombinant DNA – DNA that has been recombined from different sources Environmental impact – traits are determined by genes and the influence of the environment