Molecular

Question 1

Why does DNA exists in the chromatin form?

Answer 1

To fit in the nucleus

Question 2

What does the chromatin structure look like?

Answer 2

Negatively charged DNA loops twice around the positively charged histone octomer to form a nucleosome bead

Question 3

What amino acids are chromatin rich in?

Answer 3

Lysine and arginine

Question 4

What does H1 part of chromatin do?

Answer 4

It binds to the nucleosome and to a linker DNA stabilizing the chromatin fiber

Question 5

Which histone is not in the nucleosome core?

Answer 5

H1

Question 6

When does DNA and histone synthesis occur in miosis?

Answer 6

S phase

Question 7

What is heterochromatin?

Answer 7

Condensed, transcriptionally inactive, sterically inaccessible

Question 8

What is euchromatin?

Answer 8

Less condensed, transcriptionally active, sterically accessible

Question 9

What is DNA methylation?

Answer 9

Template strande cytosine and adenine are methylated in DNA replcation allowing for mismatch reapair enzymes to distinguish between old and new strands

Question 10

What to CPG islands do?

Answer 10

Repress transcription

Question 11

What is histone methylation?

Answer 11

Usually reversibly repressing DNA transcription but can activate sometimes

Question 12

What is histone acetylation

Answer 12

Relaxes DNA coiling, allowing for transcription

Question 13

What are the nucleotide purines?

Answer 13

A and G

Question 14

What are the nucleotide pyrimidines?

Answer 14

C, U, and T

Question 15

Which nucleotide has a methyl group?

Answer 15

Thymine

Question 16

Which nucleotide is exclusive to RNA?

Answer 16

Uracil

Question 17

Which nucleotide is exclusive to DNA?

Answer 17

Thymine

Question 18

How many H bonds does a G-C bond have?

Answer 18

3

Question 19

How many H bonds does an A-T bond have

Answer 19

2

Question 20

What are the amino acids needed for purine synthesis?

Answer 20

Glycine, Aspartate and Glutamine

Question 21

What is a nucleoside?

Answer 21

Base + deoxyribose

Question 22

What is a nucleotide?

Answer 22

Base + deoxyribose + phosphate

Linked by 3’-5’ phosphodiester bond

Question 23

What is adenosine deaminase deficiency?

Answer 23

Excess ATP and dATP imbalances nucleotide pool via feedback inhibition of ribonucleotide reducatase which prevents DNA synthesis and thus decreases lymphocyte count
A major cause of autosomal recessive SCID

Question 24

What is Lesch-Nyhan syndrome?

Answer 24

Defective purine salvage due to HGPRT
Results in excess uric acid production and de novo purine synthesis
X-linked recessive

Question 25

What does HGPRT do?

Answer 25

Converts hypoxanthine to IMP and guanine to GMP

Question 26

What are the findings of Lesch-Nyhan sydrome?

Answer 26

Intellectual disability, self-mutilation, aggression, hyperuricemia, gout, and dystonia

Question 27

What is the treatment for Lesch-Nyhan syndrome?

Answer 27

Allopurinol or febuxostat (2nd line)

Question 28

What does an unambiguous genetic code feature mean?

Answer 28

Each codon specifics only 1 amino acid

Question 29

What does a degenerate/redundant genetic code feature mean?

Answer 29

``` Most amino acids are coded by multiple codons except methionine (AUG) and tryptophan (UGG) ```

Question 30

What does a commaless or nonoverlapping genetic code feature mean?

Answer 30

Read from a fixed starting point as a continuous sequence of bases except some viruses

Question 31

What does a universal genetic code feature mean?

Answer 31

Genetic code is conserved through evolution except in mitochondria

Question 32

Describe the process of DNA replication (prokaryotes and eukaryotes);

Answer 32

Semiconservative and involves both continuous and discontinuous synthesis

Question 33

What is the origin of replication?

Answer 33

A particular consensus sequence of base pairs in genome where DNA replication begins May be single (prokar) or multiple (eukar)

Question 34

What is a replication fork?

Answer 34

Y-shaped region along DNA template where leading and lagging stands are synthesized

Question 35

What is the action of helicase?

Answer 35

Unwinds DNA template at the replication fork