AP Biology Unit 6

When does DNA replication take place?

• Whenever new genes are needed

• During the S phase of the cell cycle

• In the middle of mitosis or meiosis

• Immediately before cytokinesis begins

Answer explanation

The DNA must be replicated before cell division takes place so that the daughter cells each receive all the necessary information

Tags

IST-1

Match the following enzymes to their roles in DNA replication.

• Synthesizes the new strands of DNA

• Primase

• Unwinds the parent DNA strands

• Ligase

• Fills in the gaps in the new DNA strands

• Helicase

• Adds a small RNA "primer"

• DNA polymerase

Tags

IST-1

DNA replication involves many different enzymes. Helicase unwinds the DNA so that the parent strands can be seperated. DNA polymerase adds the nucleotides to synthesize the daughter strands. What is the role of primase?

• It adds a small RNA "primer" to allow DNA polymerase to begin

• It sorts the prime numbers of RNA into even piles

• It removes incorrecly matched nucleotides to avoid mutations

• It connects the gaps between nucleotide segments

Tags

IST-1

Label the stages of protein synthesis.

a

b

c

Translation

mRNA processing

Gene regulation

Transcription

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IST-1

Which of the following are part of a bacterial lac operon? (Select all that apply)

• Promotor

• Genes for lac enzymes

• Regulatory genes

• Enhancers

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IST-2

Match the following genetic regions to their roles:

• Promotor

• Makes a repressor protein

• Operator

• Codes for the main protein / enzymes

• Regulatory gene

• Place where transcription begins

• Genes of Operon

• The on/off switch where the repressor protein binds

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IST-2

The trp operon in E. Coli is responsible for making 5 polypeptides involved in the tryptophan synthesis pathway. When tryptophan is present, it combines with the repressor protein to block the operator. What type of operon is trp?

• Repressible

• Inducible

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IST-2

The operon model was discovered in E. Coli and is almost exclusively found in ​ (a)   .

• prokaryotes
• eukaryotes

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IST-2

After eukaryotic transcription takes place, mRNA undergoes several modifications before leaving the nucleus to take part in translation. Some sections of mRNA are cut out, and the remaining sections are spliced together to create the finished mRNA molecule. Which of the following mRNA sections are spliced together in the finished mRNA molecule?

• introns

• exons

• operons

• ribozymes

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IST-2

The human genome appears to have only about as many genes as the simple nematode worm, C. elegans. Which of the following best explains how the more complex humans can have relatively few genes?

• Human genes have unusually long introns involved in the regulation of gene expression

• More than one polypeptide can be produced from a gene by alternative gene splicing

• The human genome has a high proportion of noncoding DNA

• The human genome has a large number of SNPs (single nucleotide polymorphisms) which increases genetic variability

Tags

IST-2