ch. 12.1: dna stores information objectives: 1.describe how dna is packed within the nucleus....
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Ch. 12.1: DNA stores Information
Objectives:
1. Describe how DNA is packed within the nucleus.
2. Explain the significance of the Human Genome Project.
Vocab: Genome Histone
DNA Structure Review
Genome: Complete set of genetic material in an organism (order of bases).
Can fit into nucleus b/c of packing system.
Coiled around proteins (spools): HISTONESCoiled are coiled into helical fiber to make CHROMOSOME
Human Genome ProjectGoal: Determine …
1. Sequence of bases in the human genome.
2. Sequences code for proteins (exons).
3. Function of resulting proteins.
Began in 19901st Draft completed in 2000Government funded agency cooperated w/ private companiesResults published on web and available to scientists.
12.2: Chromosomal Disorders
Objectives:1. Relate Down syndrome
and non-separation of chromosomes.
2. Describe how chromosomes can be damaged.
3. Explain how a “jumping gene” can affect other genes.
Vocab.:TrisomyDown syndromeNon-disjunctionDuplicationInsertionDeletionInversionTranslocationTransposon
Non-disjunction
Homologous chromosomes or sister chromatids fail to separate during meiosis.
Result: Gametes with abnormal # of chromosomes… Offspring with abnormal # of offspring
Non-disjunction
Most embryos with abnormal chromosome # result in miscarriage. Cause: Random Increased risk with age (35 +)
Trisomy Having 3 of a particular chromosome.- Chromosome # = 47 Examples
Trisomy 21: Down syndrome
1 in 700 births
Most common
Cognitive and physical impairments
Trisomy 18: Edwards syndrome
(more lethal)
Trisomies & Maternal Age
Pre-egg cells in girls have gone through Meiosis I.
Meiosis II happens b4 ovulation.
Longer time lag = increase chance of nondisjunction
Trisomies of Sex Chromosomes
XXX Female
XXY: Klinefelter Male
XYY: Male
Turner’s Syndrome
XO Female
45 Chromosomes
Chromosomal Duplications Part of a chromosome is repeated. Vary from fatal to developmental abnormalities.
Chromosomal Deletions Part of a chromosome is deleted. Very serious damage
Ex: Williams Syndromehttp://abcnews.go.com/2020/video/williams-syndrome-children-friend-health-disease-hospital-doctors-13817012
Partial deletion of chromosome 7
Chromosome InversionFragment breaks and reverses on the same chromosome.
Not as lethal.
Chromosome Translocation
• List of Chromosome Disorders• http://www.netnet.net/mums/mum_chro.htm
Fragment of one chromosome attaches to ANOTHER, DIFFERENT chromosome.
If there is an UNEQUAL swap of segments, results can serious.
Transposons: Jumping Genes
• List of Chromosome Disorders• http://www.netnet.net/mums/mum_chro.htm
Discovered by Barbara McClintock
Experimented w/ corn; Jumping genes interfered w/ corn pigments.
TransposonsSingle genes that can move around.
“Jump” from one chromosome to another.
If they insert in the middle of an existing gene, that gene will be disrupted.