Formative Assessment Transcription and Translation DNA TTT mRNA UAC GAA aa Trp TranscriptionTranslation

Formative Assessment Mutations Write a DNA strand that has an insertion mutation after the 6 th base in the following strand: – A A T G C G A A G C C T What type of mutation is demonstrated below? Normal mRNA A U G T T T C G U mutated mRNA U U G T T T C G U

Chromosomal Abnormalities Name of abnormalityExampleNotes

Chromosomal Abnormalities

PA Standard 3.1.B.B1 Explain how crossing over, jumping genes, deletion and duplication of genes result in genetic variation. Student Friendly Target: – I can explain 5 chromosomal abnormalities and give real-life examples of each.

Chromosomal abnormalities nondisjunction chromosomes don’t separate properly during meiosis so chromosomes aren’t divided evenly into sperm or egg cells OR Structural abnormalities - shape/structure is incorrect deletion duplication inversion translocation

trisomy 2n+1 Nondisjunction Baby has wrong chromosome number – trisomy cells have 3 copies of a chromosome – monosomy cells have only 1 copy of a chromosome n+1n monosomy 2n-1 n-1n

Human chromosome disorders High frequency in humans – most embryos are spontaneously aborted – alterations are too disastrous – developmental problems result from biochemical imbalance imbalance in regulatory molecules? – hormones? – transcription factors? Certain conditions are tolerated – upset the balance less = survivable – but characteristic set of symptoms = syndrome

Down syndrome Trisomy 21 – 3 copies of chromosome 21 – 1 in 700 children born in U.S. Chromosome 21 is the smallest human chromosome – but still severe effects Frequency of Down syndrome correlates with the age of the mother

Sex chromosomes abnormalities Human development more tolerant of wrong numbers in sex chromosome But produces a variety of distinct syndromes in humans – XXY = Klinefelter’s syndrome male – XXX = Trisomy X female – XYY = Jacob’s syndrome male – XO = Turner syndrome female

Changes in chromosome structure deletion – loss of a chromosomal segment duplication – repeat a segment inversion – reverses a segment translocation – move segment from one chromosome to another error of replication error of crossing over

Cri du Chat Syndrome “Cat Cry” syndrome Deletion of the short end arm of chromosome 5 (usually paternal) Characterized by a high pitched mewing cry Ears are low on the head, abnormal shape Syndactyly (webbed fingers/toes) Heart anomolies

deletion – loss of a chromosomal segment duplication – repeat a segment inversion – reverses a segment translocation – move segment from one chromosome to another error of replication error of crossing over Changes in chromosome structure

Charcot- Marie-Tooth Syndrome Slow degeneration of the muscles in the foot Abnormal gait Excessive high arch Hammertoes Symptoms begin in adolescence duplication of a very large region on chromosome 17p.

deletion – loss of a chromosomal segment duplication – repeat a segment inversion – reverses a segment translocation – move segment from one chromosome to another error of replication error of crossing over Changes in chromosome structure

Pick Complex Spectrum of frontal lobe dementias maybe Parkinson’s? Mictrotubules in cells of the frontal lobe do not work properly Inversion of chromosome 17 in Tau gene region

deletion – loss of a chromosomal segment duplication – repeat a segment inversion – reverses a segment translocation – move segment from one chromosome to another error of replication error of crossing over Changes in chromosome structure

Burkitt’s Lymphoma Translocation of the Myc gene on chromosome 8 Normal Myc genes control cell growth and division Translocated Myc genes don’t function properly Leads to cancer of the lymph nodes

Barbara McClintock Discovered “jumping genes” (translocation of genes on chromosomes) Occurs during meiosis (cell division forming egg and sperm) Won Nobel Prize in 1983

Mutations Point MutationsChromosomal