Bio 108 Exam 3 (Modules 9-12)
Questions and Answers.
Structure of a strand of DNA - Answer it is composed of nucleotide subunits and has a sugar-
phosphate backbone (made of a sugar called deoxyribose and a phosphate group) covalently
bonded to nitrogen-containing bases
DNA shape - Answer the 2 strands of DNA form a double helix shape
Nitrogen-containing bases of DNA - Answer adenine bonds to thymine; cytosine bonds to
guanine
How are the nitrogen-containing bases of DNA held together? - Answer hydrogen bonds
How does a molecule of DNA replicate? - Answer one parent molecule that has two
complementary strands separates; each strand is used as a template to make a new strand;
each of the two daughter molecules will be composed of one "old" (parent) strand and one
"new" strand
Where do the 2 parent strands of DNA separate? - Answer at the origin of replication
Where does the synthesis of the 2 new complementary DNA strands occur? - Answer in the
replication bubble, using the parent strands as templates; the replication bubbles merge as the
DNA replication progresses in both directions at the replication forks
How does an organism's DNA lead to specific traits? - Answer by dictating the synthesis of
proteins
Differences between DNA and RNA - Answer RNA is a single-stranded nucleic acid; RNA
contains uracil instead of thymine; RNA contains the sugar ribose instead of deoxyribose
mRNA function - Answer to carry protein information from the DNA in the nucleus to the
cytoplasm; aka messenger RNA
tRNA function - Answer reads mRNA codons and transfers the corresponding amino acids
from the cytoplasm to the ribosome; aka transfer RNA
rRNA function - Answer deals with protein synthesis; makes sure that the codon sequence of
mRNA is accurately translated into a protein; aka ribosomal RNA
, What are the two processes that genes use to code for specific proteins? - Answer
transcription and translation
Transcription - Answer the synthesis of mRNA (messenger ribonucleic acid) under the
direction of DNA; takes place in the nucleus
Translation - Answer the synthesis of a polypeptide (which will later become a protein) under
the direction of mRNA; occurs on ribosomes in the cytoplasm
tRNA structure - Answer a strand of RNA about 80 nucleotides, twisted and folded upon itself;
At one end of the tRNA is a special triplet of bases called an anticodon that is complementary to
a codon triplet on mRNA; At the other end of the tRNA molecule is a site where one kind of
amino acid attaches
Information flow in a cell - Answer from DNA to RNA to protein; DNA makes RNA through
transcription and RNA makes protein through translation
Mutation - Answer a change in the genetic material of a cell
Point mutation - Answer a change in one base pair of a gene; can change a gene's protein
product
What can change in the DNA molecule cause? - Answer altered mRNA to be transcribed and
therefore different amino acids to be added to the polypeptide chain
Frameshift mutations - Answer involve the deletion or insertion of one or more nucleotides in
a gene; Adding or subtracting nucleotides may alter the triplet grouping of the genetic message;
most often produces a nonfunctioning polypeptide
How do viruses differ from bacterial cells? - Answer unlike bacterial cells, viruses are not
cellular and cannot reproduce outside of a host organism
True or false—after replication, each new DNA double helix consists of one old strand and one
new strand - Answer true
What cellular structure facilitates the process of translation? - Answer ribosomes
Questions and Answers.
Structure of a strand of DNA - Answer it is composed of nucleotide subunits and has a sugar-
phosphate backbone (made of a sugar called deoxyribose and a phosphate group) covalently
bonded to nitrogen-containing bases
DNA shape - Answer the 2 strands of DNA form a double helix shape
Nitrogen-containing bases of DNA - Answer adenine bonds to thymine; cytosine bonds to
guanine
How are the nitrogen-containing bases of DNA held together? - Answer hydrogen bonds
How does a molecule of DNA replicate? - Answer one parent molecule that has two
complementary strands separates; each strand is used as a template to make a new strand;
each of the two daughter molecules will be composed of one "old" (parent) strand and one
"new" strand
Where do the 2 parent strands of DNA separate? - Answer at the origin of replication
Where does the synthesis of the 2 new complementary DNA strands occur? - Answer in the
replication bubble, using the parent strands as templates; the replication bubbles merge as the
DNA replication progresses in both directions at the replication forks
How does an organism's DNA lead to specific traits? - Answer by dictating the synthesis of
proteins
Differences between DNA and RNA - Answer RNA is a single-stranded nucleic acid; RNA
contains uracil instead of thymine; RNA contains the sugar ribose instead of deoxyribose
mRNA function - Answer to carry protein information from the DNA in the nucleus to the
cytoplasm; aka messenger RNA
tRNA function - Answer reads mRNA codons and transfers the corresponding amino acids
from the cytoplasm to the ribosome; aka transfer RNA
rRNA function - Answer deals with protein synthesis; makes sure that the codon sequence of
mRNA is accurately translated into a protein; aka ribosomal RNA
, What are the two processes that genes use to code for specific proteins? - Answer
transcription and translation
Transcription - Answer the synthesis of mRNA (messenger ribonucleic acid) under the
direction of DNA; takes place in the nucleus
Translation - Answer the synthesis of a polypeptide (which will later become a protein) under
the direction of mRNA; occurs on ribosomes in the cytoplasm
tRNA structure - Answer a strand of RNA about 80 nucleotides, twisted and folded upon itself;
At one end of the tRNA is a special triplet of bases called an anticodon that is complementary to
a codon triplet on mRNA; At the other end of the tRNA molecule is a site where one kind of
amino acid attaches
Information flow in a cell - Answer from DNA to RNA to protein; DNA makes RNA through
transcription and RNA makes protein through translation
Mutation - Answer a change in the genetic material of a cell
Point mutation - Answer a change in one base pair of a gene; can change a gene's protein
product
What can change in the DNA molecule cause? - Answer altered mRNA to be transcribed and
therefore different amino acids to be added to the polypeptide chain
Frameshift mutations - Answer involve the deletion or insertion of one or more nucleotides in
a gene; Adding or subtracting nucleotides may alter the triplet grouping of the genetic message;
most often produces a nonfunctioning polypeptide
How do viruses differ from bacterial cells? - Answer unlike bacterial cells, viruses are not
cellular and cannot reproduce outside of a host organism
True or false—after replication, each new DNA double helix consists of one old strand and one
new strand - Answer true
What cellular structure facilitates the process of translation? - Answer ribosomes
