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.