TSSM BIOLOGY 2019 Unit 3 Key Topic Test 3 – Gene structure and regulation QUESTION BOOK

When comparing structural genes to regulatory genes one functional distinction between them is that A. structural genes produce enzymes B. regulatory genes produce structural proteins C. structural genes produce tran ...

When comparing structural genes to regulatory genes one functional distinction between them is that A. structural genes produce enzymes B. regulatory genes produce structural proteins C. structural genes produce transcription factors D. regulatory genes produce structural genes Question 2 Gene structure in a eukaryote includes A. stop and start instructions B. exons only C. repressors proteins D. the lac operon Question 3 A promotor region in a gene A. controls gene translation B. is found at the 3-prime end of the gene sequence C. marks the end site for transcription D. binds with RNA polymerase Question 4 When a gene in a eukaryote is transcribed, the DNA is transcribed into A. tRNA B. amino acids C. pre-mRNA D. exons only 2019 BIOLOGY KEY TOPIC TEST  TSSM 2019 Page 4 of 10 Question 5 In eukaryotes once transcription has occurred non-coding sections of the gene are removed by a process known as A. alternate slicing B. post transcriptional modification C. exon skipping D. pre-transcriptional splicing Question 6 The difference between eukaryotic and prokaryotic gene expression is A. prokaryotes have linear chromosomes making gene expression faster B. prokaryotes do not have smooth endoplasmic reticulum, so protein production is limited C. eukaryotes have introns while prokaryotes do not D. eukaryotes have fewer genes, so gene expression is less complicated Question 7 In eukaryotes when non-coding regions of pre-mRNA are removed the nucleotides are A. recycled in the ribosomes B. reused to create more amino acids C. used again to make more pre-mRNA D. moved out of the nucleus to be used during protein synthesis Question 8 A lac operon is an operon required for the metabolism of lactose in E. coli, a bacteria often found in the gut flora of humans. The reason why bacteria metabolise lactose is A. the preferred energy source, glucose, is not available B. to produce the enzyme lactase C. to control lactose intolerance in humans D. to allow the repressor to be expressed Question 9 The order of the structure of the lac operon is as follows A. repressor, promotor, operator, B. promotor, operator, lactose C. promotor, operator, lac Z D. operator, promotor, lac Z 2019 BIOLOGY KEY TOPIC TEST  TSSM 2019 Page 5 of 10 Question 10 Genes are switched on through the operation of transcription factors because A. all genes are switched off until a repressor switches them on B. transcription factors act on exons when building proteins C. it would be wasteful to produce proteins when they are not required D. when lactose is present the lac operon switches off Question 11 In the lac operon, RNA polymerase acts to build mRNA to carry the code to ribosomes for the building of three proteins lac Z, lac Y and lac A. These three proteins work independently of each other to digest and transport lactose. The structure of the three proteins must be A. primary B. secondary C. tertiary D. quaternary Question 12 RNA polymerase works to build mRNA once the operator region of the lac operon is free. The molecule that causes the RNA polymerase to start to transcription is A. the lac enzyme B. lactose C. glucose D. lactase Question 13 The regulatory gene of the lac operon turns off the structural part of the lac operon. This regulatory gene codes for a protein component that acts as the A. operator B. repressor C. promotor D. lactose Question 14 If glucose is present, the lac operon does not produce the three proteins to digest lactose. This is due to A. the repressor binding to glucose by preference B. RNA polymerase not building tRNA C. the repressor binding to the operator D. the repressor not binding to RNA polymerase 2019 BIOLOGY KEY TOPIC TEST  TSSM 2019 Page 6 of 10 Question 15 Transcription factors that switch on and off genes are proteins that are expressed by A. structural genes B. regulatory genes C. promotors D. lac Z 2019 BIOLOGY KEY TOPIC TEST  TSSM 2019 Page 7 of 10 SECTION B - Short-answer questions Instructions for Section B Answer all questions in the space provided. Write using a blue or black pen. Question 1 Genes are controlled to produce proteins when the protein is required to assist in the maintenance and functioning of the organism. a. Explain the functional distinction between structural and regulatory genes. _____________________________________________________________________ _____________________________________________________________________ b. The process of expressing genes in prokaryotes is different to eukaryotes although both produce proteins as the product. During transcription eukaryotic cells have extra processes that prokaryotes do not. What are 2 steps in transcription that only occur in eukaryotes? _____________________________________________________________________ _____________________________________________________________________ c. An additional part of RNA processing involves a process that produces multiple proteins from a single gene. What is this process called and how are different proteins produced from a single gene? _____________________________________________________________________ _____________________________________________________________________ 2 + 2 + 2 = 6 marks 2019 BIOLOGY KEY TOPIC TEST  TSSM 2019 Page 8 of 10 Question 2 In a gene there are different regions that work together to produce an operon. a. What is an operon? _____________________________________________________________________ _____________________________________________________________________ b. In each operon there is a promotor region that has a specific function. What is the function of the promotor region? _____________________________________________________________________ _____________________________________________________________________ c. There is an enzyme attached to the promotor region of an operon that facilitates gene expression and the production of the protein. What is this molecule and what molecule does it produce? _____________________________________________________________________ _____________________________________________________________________ 2 + 2 + 2 = 6 marks 2019 BIOLOGY KEY TOPIC TEST  TSSM 2019 Page 9 of 10 Question 3 The diagram below shows a simplified diagram of the lac operon a. Label the parts of the diagram 1 to 11 Label Name 1 2 3 4 5 6 7 8 9 10 11 1 2 3 4 5 6 7 8 9 10 B galactosidase Permease Transacetylase 11 2019 BIOLOGY KEY TOPIC TEST  TSSM 2019 Page 10 of 10 The lac operon allows for the digestion of lactose in E. coli and other bacteria. It produces proteins that transport and metabolise lactose in the absence of glucose. The operon has multiple parts. Give the function for the b. Operator _____________________________________________________________________ c. Promotor _____________________________________________________________________ d. Repressor _____________________________________________________________________ e. Explain the process leading to the synthesis of the three proteins produced by the lac operon. _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ The regulatory gene for the lac operon produces a protein that acts as a repressor stopping the production of the lac proteins unless lactose is present. Regulatory genes for other operons may act as activators. f. What are these repressors and activators called? ________________________________________________________________________ ________________________________________________________________________ g. If a regulatory gene for an activator is transcribed what effect would it have on the production of a protein?