Transcript Ch. 12.1: DNA stores Information

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): HISTONES
Coiled are coiled into helical fiber to make
CHROMOSOME
Human Genome Project
Goal: Determine …
1. Sequence of bases in the
human genome.
2. Sequences code for proteins
(exons).
3. Function of resulting
proteins.
Began in 1990
1st Draft completed in 2000
Government funded agency cooperated w/ private companies
Results 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.:
Trisomy
Down syndrome
Non-disjunction
Duplication
Insertion
Deletion
Inversion
Translocation
Transposon
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.
Examples
- Chromosome # = 47
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 Syndrome
http://abcnews.go.com/2020/video/williams-syndrome-children-friend-health-disease-hospital-doctors-13817012
Partial deletion of chromosome 7
Chromosome Inversion
Fragment breaks and reverses on the same
chromosome.
Not as lethal.
Chromosome Translocation
Fragment of one chromosome attaches to ANOTHER,
DIFFERENT chromosome.
If there is an UNEQUAL swap of segments, results can
serious.
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•
List of Chromosome Disorders
http://www.netnet.net/mums/mum_chro.htm
Transposons: Jumping Genes
Discovered by Barbara McClintock
Experimented w/ corn; Jumping genes interfered w/ corn
pigments.
•
•
List of Chromosome Disorders
http://www.netnet.net/mums/mum_chro.htm
Transposons
Single 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.