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Organization of DNA from smallest to largest
- Nucleotides
- Motifs
- Genes
- Chromosomes
- Nucleus
- Cell
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How many genes encoded by DNA
21,000
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How many genes in mitochondria
37
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All genes in mitochondria are essential for
Mitochondrial function
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Mitochondrial genes origin
Mother only
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DNA building block made of how many bases?
4
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Four building block bases of DNA
- 2 purines
- Adenine
- Guanine
- 2 pyrimidines
- Cytosine
- Thymine
- Also backbone of deoxiribose (5 carbon sugar)
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Guanine bonds to
Cytosine
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Both DNA and RNA
Guanine and adenine
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Used for DNA/ Used for RNA
Thymine and cytosine/Uracil and Cytosine
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Nucleoside lacks
phosphorus
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Phosphate use in DNA
Chains together carbon (nucleosides become nucleotides)
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Phosphate/sugar backbone is called
Phosphodiester backbone
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Purines found in the body but NOT in DNA
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Methylization of xanthine creates
Caffein naturally in the body
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Difference between ribose and deoxyribose (RNA and DNA)
One oxygen molecule (DNA is missing the oxygen)
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Double stranded DNA+small basic proteins (histones) + small amount of nonhistone proteins
Chromatin complex
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Arginine and lysine-rich basic proteins
Histones (part of composition of chromatin complex)
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Positive charge on AA helps bind histones to
Negative charge on DNA sugar phosphate
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Core of 8 histones with DNA wrapped around
Nucleosomes
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Nucleosomes wind up to form
Chromatin strand
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Chromatin strand winds tight to form
Chromasomes during mitosis or miosis
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Number of chromosome copies in a cell
Ploidy
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Most cells in the body are
Diploid, exception being germ cells (sperm and egg, haploid cells)
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Diploid cells have copies from
Mom and dad (one of each)
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Haploid gene has how many base pairs
3 billion
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Haploid genome has how many chromosomes?
23 (22 somatic, 1 sex)
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Haploid genome has enough DNA to code for
1.5 million genes, really only codes for 21,000 genes
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DNA that doesn't code for any of our 21,000 genes is
"Junk." Doesn't appear to code for anything to be produced. May be important in regulation of production.
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Total number of protien species produced by the body is called
Proteome
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Many protein species are regulated by
MicroRNA
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Small non-coding RNA that control translation and post-translational changes
Micro RNA (miRNA)
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Deregulation of miRNA can lead to
Diabetes, cancer, schizophrenia, depresion, etc.
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Two parts of eukaryotic DNA
- Unique DNA sequences (genes)
- Repeat sequences ("junk")
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Trinucleotide (microsatellite) repeats and disease - repeat sequences repeated too many times cause
Disease! e.g. - Huntingtons, Kennedy, Fragile X, etc.
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Dispersed repetitive sequences are found where?
Found mingled around coding genes (unique DNA sequences)
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Endonucleases are
Non-specific DNA "clippers," long interspersed elements - 7000 bp
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Reverse transcriptase does what?
Codes RNA, turns it back into cDNA
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Lines v sines
- Lines - long interspersed elements (7000 bp)
- Sines - Short interspersed elements (90-500 bp)
- bp=base pairs
- Both are dispersed repetitive sequences
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Where are genes located?
Located in chromosomes and in mitochondria
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Genes contain two regions -
- Promoter region
- Control region
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How much of a gene sequence is required for generating a product?
The entire sequence is required for the product to be produced
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What is epigenetics?
Stable changes to a gene structure, without changing the DNA sequence
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If there is no change in gene structure, how do epigenetics work?
Changes in gene expression
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Epigenetics are controlled by
- **Methylation of cytosines
- Tissue-specific chromatin alterations
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What do DNA strands wrap around for storage?
Proteins called Histones (spools for DNA to wrap around)
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Acetylation of lysine does what to DNA-histone interaction?
Weakens the interaction, easier for transcription factors to access the DNA strand
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Histone deacetylase does what to DNA-histone interaction?
Tightens it, makes it more difficult for transcription factors to access DNA strand
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Two ways to describe compaction of DNA in chromatin
- Euchromatin - loosely packed, transcriptionally active
- Heterochromatin - densely packed regions, genetcally inactive
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Unhealthy epigenetic alterations
- Excess oxidation and free radicals
- Tobacco
- Excess alcohol
- Pychological stress (hormones)
- Shiftwork
- Chronic inflammation
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Healthy epigenetic alterations
- Polyunsaturated fats
- Fruits and veggies (polyphenols)
- Folate and vitamin B12
- Selenium
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Epigenetic changes in fetus: Depression causes
- Exposure of hypothalmlic-pituitary adrenal axis with higher levels of corticotrophin releasing hormone
- Babies born with less developed prefrontal cortex
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Epigenetic changes in fetus:diabetes causes
- Hyperinsulinemia in the fetus, increase oxygen consumption and metabolism
- Causes chronic intraunterine tissue hypoxia
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