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20 Cards in this Set
- Front
- Back
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What is the relation between genes and a species (what makes us, us)?
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A species is not determined by the number of genes but by how, when and how frequently that they are expressed.
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What is a nucleotide made up of?
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an aromatic base
5 carbon sugar (deoxyribose for DNA and ribose for RNA) and a phosphate group |
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What bases make up Purines?
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Guanine (G) and Adenine (A)
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What bases make up Pyrimidines?
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Thymine (T)
Cytosine (C) Uracil (U) |
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What type of bond links nucleotides together?
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Phosphodiester Bond
links the 5'-OH of one (deoxy)ribose to the 3'-OH of another (deoxy)ribose |
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What type of bond links the sugar base to the backbone
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glycosidic bond
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What pairing of bases are the most stable?
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Guanine and Cytosine: This binding involves 3 hydrogen bonds.
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What orientation should DNA stands be in to form base pairs?
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ANTIPARALLEL.
The base pairs are perpendicular to the helix axis |
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What was the major discovery about DNA that Watson and Crick uncover?
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The sequence of nucleotides in one strand determines the sequence in the complementary strand
COMPLEMENTARY: because A always pairs with T and G always pairs with C, the sequence of one strand of DNA immediately yields the sequence of the other strand. |
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Melting or Denaturation
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separates DNA into two strands. The specific temperature where this occurs is called the melting temperature.
The higher the G-C content of the helix the higher the Tm and the longer the chain or base paired segment the higher the Tm |
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What is DNA Repair
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DNA repair is the set of biochemical mechanisms that recognize genomic alterations and replaces those alterations with their correct counterparts
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Why do We Need it:?
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-DNA can be damaged chemically by many agents
-damage changes DNA sequence, causes chromosomal rearrangements and deletions, and blocks replication, all of which result in genome mutations * accumulation of mutations causes cancer and other diseases |
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Basic Steps of repair of Chemical Damage
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1. Recognize damage.
2 Remove damage by excising part of one strand. 3. Re-synthesize to fill gap (use other strand as template). 4. Ligate to restore continuity of sugar-PO4 backbone |
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Xeroderma pigmentosum
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hypersensitivity to sunlight/UV, increased skin cancer incidence, premature aging.
Defects in nucleotide excision repair |
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Cockayne syndrome
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impaired nervous system development, hypersensitivity to sunlight, premature aging.
Defects in nucleotide excision repair |
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Trichothifodystrophy
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brittle hair and nails, in some cases UV sensitivity.
Defects in nucleotide excision repair |
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Hereditary nonpolyposis colorectal cancer:
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high risk of predominantly colon cancer, but also cancers of many other organs.
Defects in mismatch repair |
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Gene
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= a DNA segment that includes information copied into RNA plus sequences that determine when, where, and at what rate the RNA is transcribed.
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Transcription
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The process of producing a single-stranded RNA complementary to one strand of a double-stranded DNA molecule
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rRNA
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The ribosome is a huge RNA-protein complex that “translates” mRNA sequences into protein sequences.
rRNA molecules comprise >60% of ribosome mass. rRNAs carry out the activities of the ribosome. 3 rRNAs of different size and sequence in bacteria. 4 rRNAs different rRNAs in eukaryotes. Comprise 85-90% of the total cellular RNA mass |
