Chromosomes (3.2)
Autoradiography
One of the first methods that allows us to see DNA under an electron microscope
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What we learned about Chromosomes:
Prokaroyotic Chromosomes
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Eukaryotic Chromosomes
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What is a Chromosome?
Chromosomes are tightly coiled DNA strands.
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Structure of a chromosome
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Homologous Chromosomes
In Eukaryotes, chromosomes come in pairs called homologous chromosomes
Pairs have:
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Humans contain 46 chromosomes or 23 pairs of homologous chromosomes
Where do the pairs come from?
Where do the pairs come from?
- You get one chromosome of each pair from mom and one of each pair from dad
- Allows for error to occur and not affect the individual
- Allows for greater genetic diversity through the recombination of genes during meiosis (sexual reproduction)
Karyotypes
A karyotype is the number and appearance of chromosomes in the nucleus of an eukaryotic cell.
- The term is also used for the complete set of chromosomes in a species, or an individual organism.
- Must have cells from the individual person or organism.
- For us- this is easy, cheek cells, hair, etc… can be used to create a kayotype.
- But for an unborn child… this is a much more difficult process.
Karyotyping a fetus
Amniocentesis (also referred to as amniotic fluid test or AFT) is a medical procedure used to diagnosis chromosomal disorders.
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Understanding a Karyotype
In humans, there are 23 homologous pairs…
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Beyond male and female, Karyotypes can also help us detect abnormalities with chromosome numbers.
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Identify Male/ Female- normal or abnormal?
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Species Comparisons
When comparing various species at different levels:
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Loci Database
Genome: whole genetic information of an organism
Gene: heritable factor that consists of a length of DNA and influences specific characteristics
Loci: Location of a gene (ie. 7q36.2)
Due to the Human Genome Project, we now have lots of information on the genes in human DNA. Some of this is well understood others are not. But the following Database: Online Mendelian Inheritance in Man, allows us to search for various genes and find information on their location and what they do.
Try looking up some of the following gene codes and answering the following: actual name, location, what it codes for, what alleles exist for the gene, phenotypes/ diseases associated with the gene, and an interesting fact or two.
Gene: heritable factor that consists of a length of DNA and influences specific characteristics
Loci: Location of a gene (ie. 7q36.2)
- Read: 7th chromosome, q arm (long arm), 3rd region, 6th band, sub-band 2
Due to the Human Genome Project, we now have lots of information on the genes in human DNA. Some of this is well understood others are not. But the following Database: Online Mendelian Inheritance in Man, allows us to search for various genes and find information on their location and what they do.
Try looking up some of the following gene codes and answering the following: actual name, location, what it codes for, what alleles exist for the gene, phenotypes/ diseases associated with the gene, and an interesting fact or two.
- TP53
- DRD4
- CFTR
- HBB
- FB
- TDF
- LP(a)
- ATP5A1
- BRAC1
- EGFR
- HLA