Ch. 7 Dna - Biochem

Front 1

Pyrimidines

Back 1

Look like purines except they aren't "so pure" having been CUT (cytosine, Uracil, Thymine) in half leaving a single hexagonal structure, rather then the hex-pent structure of purines.

Front 2

Purines

Back 2

"Pure and unCUT" and consist of Adenine and Guanine. Since they are uncut, they have 2 rings Hex+Pent.

Front 3

Nucleoside

Back 3

purine/pyrimidine + "S"ugar (ribose or deoxyribose)

Front 4

Nucleotide

Back 4

Nucleoside + phosphaTe moiety = nucleoTide (means we have added the phosphate to the nucleobase + sugar

Front 5

Nucleotides in sequence

Back 5

DNA or RNA

Front 6

Thymine

Back 6

Specific to DNA

Front 7

Uracil

Back 7

Specific to RNA

Front 8

Steps of DNA replication

Back 8

1. Helicase unwinds. SSBPs (single-stranded binding proteins) prevent strands from rejoining or being attacked by enzymes that attack single strands.

2. Topoisomerase (e.g. DNA gyrase) reduces the supercoiling that occurs during unwinding. Primase synthesizes RNA primer, which initiates DNA polymerization).

3. DNA ligase- connects newly formed fragments (Okazaki fragments) of DNA with one another to form a single chain.

4. Endonucleases--hydrolyze connections between nucleotides that lie within the central area of the nucleotide chain. (exonucleases can hydrolyze terminal positions. A specific endonuclease can help remove segment of DNA rendered defective by UV light.

Front 9

DNA Repair

Back 9

UV light can damage DNA by making two adjacent thymine bases fuse covalently. Endonuclease makes a nick in DNA strand on one side of the defective dimer, then an exonuclease removes damaged dimer. DNA polymerase adds replaced nucleotides, and DNA ligase reattaches DNA to the original strand.

Front 10

Transcription

Back 10

1. RNA polymerase sequentially polymerizes nucleotides on the DNA template to form an RNA copy of one of the DNA strands.

2. Promoters are regions on DNA that signal RNA polymerase where to begin polymerization. DNA contains stop signals where RNA transcription should stop.

3. Resulting RNA may be modified. 3 general types of RNA : (1. messenger: carries message (in codons) of the specific protein to be synthesized on ribosomes. 2. Transfer: transfers individual specific amino acids to be linked up on mRNA molecules. 3. Ribosomal (integral part of ribosomal structure. Some ribosomal RNA--called ribozymes--are catalysts for peptide bone formation).

Front 11

Anticodon

Back 11

The recognition site on a transfer RNA molecule that recognize a specific mRNA codon. It's the anticodon of tRNA that actually recognizes the mRNA sequence.

Front 12

Enzyme that attaches amino acids to their corresponding tRNA

Back 12

Amino acyl-tRNA synthetase

Front 13

Hydroxyproline and hydroxylysine

Back 13

Components of collagen that are formed from proline and lysine that are hydroxylated while part of the precursor protein molecule.

Front 14

ATP, GTP, NADH, FADH2, CoA, and cyclic AMP.

Back 14

Adening and guanine are part of ATP and GTP. Adening is part of NADH, FADH2, CoA, and cyclic AMP.

Front 15

UDP-glucse

Back 15

Uracil is part of UDP glucose (an important glycogen intermediate.

Front 16

Uric Acid

Back 16

Purine have a "restroom" in which urate (uric acid) is formed as a waste product of purine degredation. The pyrimidines don't actually have a waste product, and rather than forming urates, they tend to convert to other molecules that can be used in other metabolic reactions.

Front 17

Pyrimidine waste

Back 17

Generally none, they convert to other metabolites. Thymine may eventually become 3-aminoisobutyrate-->succinyl CoA (an important molecule in the Krebs cycle)

Front 18

Purine Synthesis

Back 18

1. glycine, 2. tetrahydrofolate (donates 1 Carbon), 3. glutamine, 4. CO2, and 5. aspartate

Entry into purine synthesis begins with "IMP" (Inosine monophosphate)

Front 19

Purine Salvage

Back 19

Instead of taking the effort to laboriously syntehsize purines, we can utilize purines that have already been formed, and use them to make new nucleotides. PRPP + purine--> purine nucleotide + PPi.

Front 20

Pyrimidine synthesis

Back 20

Snthesized from aspartate and carbamoyl phosphate. Enters DNA spathway at "UMP"

Front 21

Carbohydrates can become nucleotides via what mechanism?

Back 21

Ribose 5-P from the pentose shunt can become 5-R-Ribosyl-PP (PRPP) which is then used in purine synthesis and pyrimidine synthesis.