Question

wlhs biology oppelt
the monomer of nucleic acids is the nucleotide. all nucleic acids are formed from a series of these nucleotides. nucleotides consist of three parts: a five - carbon sugar, a phosphate group and a nitrogen base.

1. what is the building block of nucleic acids?
2. what are the three parts of this monomer?

a._
b._
c._
the structure of dna resembles that of a twisted ladder. this twisted ladder of dna is called a double helix. the rails of the dna ladder are made from alternating sugars and phosphates (sugar - phosphate - sugar - phosphate - sugar...). in dna, the sugar is called deoxyribose. the rungs of the ladder are made of four different kinds of bases, with one base hanging off of the sugar portion of each rails. the four bases are a, t, c and g. the rails of the ladder are held together because the bases from one rail bond to the bases from the other rail to form rungs. the bases from one side of the ladder attach to the bases hanging from the other rail. this keeps the ladder together. the bases attach to one another in a very specific way: a bases always attach to t bases, and c bases always attach to g bases.

1. describe the structure and shape of dna.
2. what are the rails of the ladder made of?

a._ b._

1. how are the rails of the ladder kept together?
2. what are the four different dna bases?

a._ c._
b._ d._

1. what part of the ladder do these bases form?
2. a always pairs with what base?

rna is very similar to dna in all ways except for a few differences. first, where the sugar in dna is deoxyribose, the sugar in rna is ribose. second, where dna is a double helix, rna has just one strand. third, where the bases in dna are c,g, a and t, in rna the bases are c, g, a and u. the u in rna takes the place of the t in dna. fourth, dna cannot leave the nucleus of the cell and rna can.

1. list four differences between dna and rna.

a._ c._
b._ d._

1. list three similarities between dna and rna.

a._
b._
c._

Explanation:

1. The text clearly states that the monomer (building block) of nucleic acids is the nucleotide.
2. The text mentions that nucleotides consist of three parts: a five - carbon sugar, a phosphate group, and a nitrogen base.
3. The text describes the structure of DNA as resembling a twisted ladder, called a 'double helix'.
4. The text says the rails of the DNA ladder are made from alternating sugars and phosphates.
5. The text explains that the rails are held together because the bases from one rail bond to the bases from the other rail.
6. The text lists the four DNA bases as A, T, C, and G.
7. The text indicates that the bases form the rungs of the ladder.
8. The text states that 'A' bases always attach to 'T' bases.
9. The text lists four differences: sugar in DNA is deoxyribose (RNA is ribose), DNA is double helix (RNA is single - stranded), DNA has bases C, G, A, T (RNA has C, G, A, U), DNA cannot leave the nucleus (RNA can).
10. Similarities (not explicitly listed in the text but can be inferred from the fact that they are both nucleic acids): Both are nucleic acids, both have a sugar - phosphate backbone, both have nitrogen bases (some common like C, G, A).

Answer:

1. Nucleotide
2. a. Five - carbon sugar; b. Phosphate group; c. Nitrogen base
3. DNA resembles a twisted ladder and is called a 'double helix'
4. a. Sugar; b. Phosphate
5. The bases from one rail bond to the bases from the other rail
6. a. A; b. T; c. C; d. G
7. Rungs
8. T
9. a. DNA sugar is deoxyribose, RNA sugar is ribose; b. DNA is double - helix, RNA is single - stranded; c. DNA bases: C, G, A, T; RNA bases: C, G, A, U; d. DNA cannot leave nucleus, RNA can
10. a. Both are nucleic acids; b. Both have sugar - phosphate backbone; c. Both have nitrogen bases (C, G, A in common)