Biology 12

326 MHR • Unit 3 Molecular Genetics

17.Which of the following is not used in the chain

termination sequencing reaction?

(a)DNA polymerase

(b)dideoxynucleotides

(c)a buffer solution

(d)a primer strand of nucleotides

(e)regular nucleotides

18.The process of cloning a mammal using genetic

material from an adult donor involves a number

of steps. Select the answer below that shows

three of these steps in the correct order.

(a)remove nuclei from egg cells; fragment DNA

from genetic donor cells with endonuclease;

culture egg cells and DNA from genetic

donor cells

(b)remove nuclei from donated egg cells; treat

cell culture with an electric current; implant

clone embryos into surrogate parent

(c)collect cells from genetic donor; transplant

nuclei from genetic donor cells into egg

cells; culture cells to stop cell division

(d)culture genetic donor cells to stop cell

division; insert new genetic material;

culture cells to produce early embryos

(e)collect cells from genetic donor; culture egg

cells to stop cell division; transplant nuclei

from genetic donor cells into egg cells

Short Answers

In your notebook, write a sentence or a short

paragraph to answer each of the following questions.

19.Explain how Chargaff’s findings with respect to

the composition of DNA provided evidence for

the role of DNA in heredity.

20.Draw a DNA molecule that has the nucleotide

sequence ATTCTGGC along one strand. Label

the 5 ′and 3 ′ends.

21.Explain the role played by each of the following

forces in maintaining the structure of DNA

within eukaryotes.

(a)hydrogen bonds

(b)hydrophilic and hydrophobic interactions

(c)phosphate bonds

(d)histone–histone interactions

(e)DNA–histone interactions

22.Explain how elongation of a daughter DNA

strand takes place

(a)in the direction of the movement of the

replication fork

(b)in the direction opposite to the movement

of the replication fork

23.The genome of a eukaryote is made up of genes

along with various kinds of non-coding DNA

sequences. Give one example of how non-

coding DNA could play a role in each of the

following functions.

(a)regulating gene expression

(b)increasing the organizational complexity of

an organism

(c)governing the life span of a cell

24.Copy and complete the following table.

Use the genetic code table on page 254 to answer

questions 25–27.

25.What amino acid is associated with each of the

following codons?

(a)GCC (c)ACU

(b)UUU

26.What anticodon sequences are associated with

each of the following amino acids?

(a)leucine (c)glycine

(b)tyrosine

27.What features of the genetic code help protect

the cell from the effects of mutations? Give

specific examples using information from

Table 8.1.

28.Answer the following questions in regard to

the electron micrograph pictured on page 327.

(a)What cellular process or structure does this

figure show? Describe its significance in

relation to the metabolism of a cell.

(b)Where in the cell is this process taking

place?

(c)Identify each of the labelled structures.

(d)Identify the 5 ′end of the nucleic acid(s)

shown.

Polypeptide

Location in eukaryotic

cells (cytoplasm or

nucleus) Function(s)

DNA polymerase

activating enzymes

excision repair

enzymes

RNA polymerase

release factors

helicase

RNA primase