Nucleic Acids

Question 1

Define nucleotides. What are they composed of?

Answer 1

Monomeric units of nucleic acids. Composed of a base, a sugar, and a phosphate

Question 2

What is the difference between a nucleotide and a nucleoside?

Answer 2

Nucleosides lack the inorganic phosphates of nucleotides.

Question 3

What is the difference in the sugar of DNA and RNA?

Answer 3

DNA has 2’ deoxyribose. RNA has ribose.

Question 4

What are the purine bases? How many rings do they have?

Answer 4

Adenine and guanine. 2 rings.

Question 5

What are the pyrimidine bases? How many rings do they have?

Answer 5

Cytosine and Thymine. Uracil in RNA. 1 ring.

Question 6

How are the backbones of both DNA and RNA formed?

Answer 6

They are linked by phosphodiester bonds between the 3’ -sugar of one nucleotide and the 5’ -sugar of the next nucleotide.

Question 7

How is the genetic information in DNA encoded?

Answer 7

Genetic information is encoded by the sequence of the nucleotide bases in DNA.

Question 8

What direction are the strands in DNA?

Answer 8

They are antiparallel, with one strand going in the 5’ to 3’ direction, and the other going in the 3’ to 5’ direction.

Question 9

What are the complementary bases? What type and how many bonds hold them together?

Answer 9

Adenine and Thymine (or Uracil in RNA): 2 hydrogen bonds.

Guanine and Cytosine: 3 hydrogen bonds.

Question 10

What are the 3 major types of RNA and what are their functions?

Answer 10

1. mRNA: codes for proteins
2. rRNA: form the basic structure for the ribosome and catalyze protein synthesis
3. tRNA: central to protein synthesis as adaptors between mRNA and amino acids

Question 11

What is siRNA?

Answer 11

Small interfering RNA. Turn off gene expression by directing degradation of selective mRNAs and the establishment of compact chromatin structures.

Question 12

What is miRNA?

Answer 12

Micro RNA. Regulate gene expression typically by blocking translation of selective mRNAs.

Question 13

Define chromatin.

Answer 13

Histone-DNA complex. DNA storage.

Question 14

Define nucleosomes.

Answer 14

Basic subunit of chromatin.

Question 15

Define histone.

Answer 15

Proteins that contain large amounts of arginine and lysine, thus giving it a positive charge. This neutralizes negative charge of phosphate backbone of DNA. Octamer which there are 4 main types with a 5th one involved in linker DNA.

Question 16

Define ribosomes.

Answer 16

Ribonucleoprotein complexes on which protein synthesis occurs.

Question 17

Define solenoids.

Answer 17

Strings of nucleosomes wound into helical, tubular coils .

Question 18

Define euchromatin.

Answer 18

Chromatin that is loose or “open” for transcription and replication.

Question 19

Define heterochromatin.

Answer 19

Chromatin that is most highly condensed, and thus closed to processes such as transcription.

Question 20

What are HATs?

Answer 20

Histone acetyltransferases. Loosen up chromatin and permit transcription.

Question 21

What are HDACs?

Answer 21

Histone de-acetyltransferases . Compact chromatin and silence genes.

Question 22

What is the importance of FISH?

Answer 22

Important for diagnosing chromosomal disorders. Can show you whether or not chromosomes are fused together.

Question 23

Define karyotype.

Answer 23

The number and visual appearance of the chromosomes in an organism.

Question 24

Define gene.

Answer 24

The fundamental units of heredity and are arranged linearly along each chromosome .

Question 25

How are chromosomes distinguished?

Answer 25

By their size, staining patterns, and FISH color.

Question 26

DNA molecule that forms a linear chromosome must contain what?

Answer 26

1. Centromere
2. Two telomeres (ends)
3. A replication origin

Question 27

Rule of Thumb regarding gene regulation and complexity of organism.

Answer 27

Higher up the organism, the more complex the gene regulation.