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Flashcards in Biochem - Molecular Deck (178)
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1

How many subunits make up a nucleosome core?

Eight; two of each of the four histone types

2

What is the charge on DNA?

Negative

3

The molecule shown here is synthesized from ____ and ____.

Carbamoyl phosphate and aspartate

4

In this diagram, what enzyme is sealing the Okazaki fragment together with the lagging strand?

DNA ligase

5

In this picture, what is the function of single-stranded binding proteins?

They prevent strands from reannealing

6

How many times does the DNA loop around each octamer (nucleosome core)?

Two

7

What histone type is found between the nucleosome cores (the histone octamers)?

H1

8

What is the charge on histone octamer?

Positive; giving the histones affinity for negatively charged DNA

9

Predominance of which two amino acids gives histones a positive charge?

Lysine and arginine

10

What are the names of the four subunits of a nucleosome core?

Histones H2A, H2B, H3, and H4

11

What is DNA called when it is condensed and transcriptionally inactive?

Heterochromatin

12

Which histone is not part of the nucleosome core?

H1

13

What is transcriptionally active DNA called?

Euchromatin; it is uncondensed and accessible to replication enzymes

14

How many hydrogen bonds are there between adenine and thymine?

Two

15

What are the two purines?

Adenine (A) and guanine (G) (remember: PURe As Gold: PURines)

16

Which is stronger: a guanine-cytosine bond or an adenine-thymine bond?

A guanine-cytosine bond, because it has three hydrogen bonds; an adenine-thymine bond only has two

17

What are the three pyrimidines?

Cytosine (C), thymine (T), and uracil (U) (remember: CUT the PY [pie]: PYrimidines)

18

What physical property do nucleic acids with increasing proportions of guanine-cytosine bonds display?

Increasing melting temperatures due to the tighter binding of the strands

19

How many rings do pyrimidine molecules have?

One

20

How many rings do purine molecules have?

Two

21

What molecule does deamination of cytosine yield?

Uracil

22

Nucleoside = _____ + ribose

Base

23

In what type of nucleic acid is uracil found?

RNA

24

What type of bond links nucleotides?

3;-5; phosphodiester bond

25

In what type of nucleic acid is thymine found?

DNA

26

What nucleotide has a methyl group?

Thymine

27

Nucleotide = _____ + phosphate

Nucleoside

28

What are the two precursors to creating the pyrimidine ring?

Carbamoyl phosphate and aspartate

29

In de novo nucleotide synthesis, _____ (purines/pyrimidines) are made from IMP precursors, while _____ (purines/pyrimidines) are made from orotate precursors.

Purines; pyrimidines

30

What quality of trimethoprim makes it a good antibiotic?

Its target is bacterial dihydrofolate reductase, inhibiting DNA synthesis