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First Aid > Biochemistry Notes > Flashcards

Biochemistry Notes Flashcards

1
Q

What is the specific makeup of nucleosome?

A

The nucleosome is composed of an octamer of histone proteins, designated as H2A, H2B, H3 and H4

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2
Q

How many histone proteins make up nucleosome?

A

4

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3
Q

What is the mnemonic for chromatin types?

A

Eu = true, “truly transcribed” HeteroChromatin = Highly Condensed

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4
Q

What is the general mechanism of action of methylation in Prokaryotes?

A

Template strand cytosine and adenine are methylated in DNA replication, which allows mismatch repair enzymes to distinguish between old and new strands in prokaryotes.

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5
Q

What does DNA methylation at CpG islands do?

A

DNA methylation at CpG islands prevent transcription

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6
Q

Why is DNA condensed in chromatin form?

A

DNA is condensed in chromatin form to fit into the nucleus

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7
Q

What makes up the nucleosome?

A

An octamer composed of four histone proteins

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8
Q

What is the secondary structure of a nucleosome molecule?

A

A negatively-coiled DNA structure wrapped around a positively coiled octamer protein

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9
Q

What is the common name for nucleosomes?

A

Beads on a string

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10
Q

How is chromatin stabilized?

A

The H1 histone protein binds to linker DNA and to the nucleosome

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11
Q

Histones are rich in what amino acids?

A

Lysine and Arginine

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12
Q

During Mitosis, what is the form of DNA? How does it take this form?

A

DNA condenses during mitosis to form chromsomes

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13
Q

When does DNA synthesis take place during the life cycle of a cell?

A

S phase

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14
Q

When does Histone synthesis take place during the life cycle of a cell?

A

S phase

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15
Q

What is the mechanism of action of histone acetylation?

A

Histone acetylation facilites transcription by relaxing the coiling of DNA molecules.

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16
Q

How many ring structures in Purines?

A

2

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17
Q

How many ring structures for pyrimidines?

A

1

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18
Q

Purines can be utilized to produce what nitrogenous base?

A

Adenine and Guanine

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19
Q

Pyrimidines can be utilized to produce what nitrogenous base?

A

Cytosine, Uracil and Thymine

20
Q

What is a mnemonic to remember purines?

A

PURe As Gold

21
Q

What is a mnemonic to remember pyrimidines?

A

CUT the PY(pie)

22
Q

What is a nemonic to remember the chemical group attached to thymine?

A

THYmine has a meTHYl

23
Q

What is the reactant, general chemical reaction for the production of uracil?

A

Deamination of cytosine creates uracil

24
Q

What is the difference between RNA and DNA when you consider the nitrogenous bases?

A

DNA has thymine and RNA has uracil

25
Q

What bond is stronger, G-C bond or A-T bond? Why?

A

G-C bond, 3 H-bonds is strong than A-T bond, 2 H-bonds

26
Q

How can you change the type of nitrogenous bases to increase the melting point of a DNA molecule?

A

Increase the number of G-C bonds

27
Q

What amino acids are needed for Purine synthesis?(3 points)

A

Glycine, Aspartate and Glutamine

28
Q

What is the nemonic used to remember the amino acids needed for purine synthesis?

A

Glycine Aspartate Glutamine or GAG

29
Q

What are the general chemical components of a nucleoside?

A

base + (deoxy)ribose (Sugar)

30
Q

What are the general chemical components of a nucleotide?

A

base + (deoxy)ribose + phosphaTe; lined by 3’-5’ phosphodiester bind

31
Q

What is the first difference between purine and pyrimidine synthesis?

A

Orotic acid is a temporary base for pyrimindines

32
Q

What is the first step in purine synthesis?

A

Starts with sugar and phosphate

33
Q

What is the first step in pyrimindine synthesis?

A

Start with temporary base: orotic acid

34
Q

What is the second step of pyrimindine synthesis?

A

Add sugar and phosphate to Orotic acid

35
Q

What is the second step of purine synthesis?

A

Add base to sugar and phosphate

36
Q

What is the third general step of pyrimidine synthesis?

A

Modify the base

37
Q

What substances are created first with purine and pyrimidine synthesis?

A

Ribonucleotides are synthesized first

38
Q

During purine and pyrimidine synthesis, ribonucleotides are converted to what? What enzyme catalyzes this step?

A

Ribonucleotides are converted to deoxyribonucleotides by ribonucleotide reductase

39
Q

What substance is involved in de novo pyrimidine synthesis and the urea cycle?

A

Carbomyl phosphate

40
Q

What drug blocks dihydroorotate dehydrogenase?

A

Lefunomide

41
Q

What drug inhibits ribonucleotide reductase?

A

Hydroxyurea

42
Q

What drug inhibits dihydrofolate reductase in humans?

A

Methotrexate

43
Q

What drug inhibits dihydrofolate reductase in bacteria?

A

trimethoprim

44
Q

What drug inhibits dihydrofolate reductase in protozoa?

A

pyrimethamine

45
Q

What is the first step in the purine salvage pathway?

A

HGPRT + PRPP

First Aid (7 decks)

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