Review

Question 1

a linear, unbranched polymer having the monomeric subunits- four chemically distinct nucleotides

Answer 1

DNA

Question 2

Why are positions on the pentose given a prime

Answer 2

To avoid ambiguity between the numbering systems of the heterocyclic rings (bases) and the sugar

Question 3

provides the structural support for the DNA double helix

Answer 3

sugar-phosphate backbone

Question 4

how many base pairs in DNA make a complete turn

Answer 4

10

Question 5

refers to the over- or under-winding of a DNA strand and is an expression of the strain on that strand.

Answer 5

DNA supercoiling

Question 6

-important for compacting DNA for packaging within all cells
-reduces the space and allows for much more DNA to be packaged.

Answer 6

supercoiling of DNA

Question 7

When the DNA helix has the normal
number of base pairs per helical turn it is in the _______________ state

Answer 7

relaxed

Question 8

the number of times one strand crosses over (or wraps around) the other

Answer 8

linking number

Question 9

why is thymine used in DNA instead of uracil

Answer 9

thymine has a higher resistance to photochemical mutation, which makes genetic message more stable.

Question 10

A single substitution in base that leads to
production of stop codon and terminate protein synthesis.

Answer 10

Nonsense mutation

Question 11

Mutations that insert or delete individual bases cause a shift in the triplet sets after the site of mutation

Answer 11

frameshift mutation

Question 12

___________ has the least effect; will affect only one amino acid while ____________mutations have huge effects

Answer 12

substitution
frameshift

Question 13

the sequence of mRNA that is complementary to the sequence of one strand of DNA

Answer 13

antisense or template strand

Question 14

The mRNA that is identical (apart from the replacement of T with U) to the other strand of DNA

Answer 14

coding or sense strand

Question 15

The convention for writing DNA sequences is that the top strand is the ________ strand and runs 5′ to 3′.

Answer 15

coding

Question 16

the sequences in the DNA molecule that code for the
amino acid sequences of corresponding proteins.

Answer 16

exons

Question 17

the DNA sequence in a eukaryotic gene that is not
translated into a protein.

Answer 17

introns

Question 18

why is alternative splicing done

Answer 18

to remove introns

Question 19

the overall length of a gene is determined largely by its _____________

Answer 19

introns

Question 20

The exons of some genes appear homologous to the exons of others suggesting a common
exon _______________________

Answer 20

ancestry

Question 21

a change in the nucleotide sequence of the genome, caused by a replication error or by a mutagen

Answer 21

mutation

Question 22

-no change in coding function of genome
-A substitution mutation that does not change the amino acid sequence of the polypeptide product is a silent mutation

Answer 22

synonymous change

Question 23

-mutation altering the codon
-A mutation in the coding region alter the amino acid sequence of the polypeptide product, resulting in either a missense codon (for a different amino acid) or a nonsense (termination) codon

Answer 23

nonsynonymous change

Question 24

having no effect on the phenotype of the organism

Answer 24

neutral mutation

Question 25

regions where mutations occur most frequently

Answer 25

hotspots

Question 26

capsid

Answer 26

protein coat containing nucleic acid of viral genomes

Question 27

nucleoid

Answer 27

bacterial genome organized as multiple loops compacted by nucleoid associated proteins such as H-NS (histone-like, nucleoid structuring protein)

Question 28

-Very long duplex of DNA is packaged into thread like
structures called chromosomes
-ensures that DNA is replicated and distributed
appropriately during cell division.

Answer 28

chromosomes

Question 29

• The region of the chromosome that is responsible for its
  segregation at mitosis and meiosis

Answer 29

centromere

Question 30

-seal the chromosome ends and facilitate meiotic chromosome reorganization for efficient pairing and recombination of homologous chromosomes.
-use reverse transcriptase to extend the very ends of chromosomes and solves the shortening of chromosomal ends during replication.

Answer 30

telomere

Question 31

DNA is packaged in the nucleus by association with DNA binding proteins called ________________proteins in chromatin

Answer 31

histone

Question 32

fundamental subunit of chromatin

Answer 32

nucleosome

Question 33

how many histone proteins are present on a nucleosome

Answer 33

8

Question 34

the histone proteins form a barrel shaped ___________ with the DNA wound _________ around the outside

Answer 34

octamer
twice

Question 35

what are the core histones

Answer 35

H2A, H2B, H3, and H4.

Question 36

what amino acid residues are present in histones

Answer 36

arginine and lysine residues, resulting in a high affinity for DNA

Question 37

Histones ____________ are among the most conserved proteins
known, and the core histones are responsible for DNA
packaging in all eukaryotes.

Answer 37

H3 and H4

Question 38

Each of the core histones has a histone fold domain that contributes to the central protein mass of the nucleosome, sometimes referred to as the ___________________

Answer 38

globular core

Question 39

The positive charge on lysine is neutralized upon _____________________, whereas methylated lysine and arginine retain their positive charges.

Answer 39

acetylation

Question 40

In eukaryotic cells, replication of DNA occurs in what phase?

Answer 40

S phase

Question 41

In ____________phase everything except DNA begins to be doubled: RNA, protein, lipids, and carbohydrates.

Answer 41

G1