Tut 11 - Cancer (teacher)

St Andrew’s Junior College Molecular Biology of Cancer 2022 H1 Biology 1 Full Name: Civics group: 21S Index no.: Date: Core Idea 2: Genetics and Inheritance Molecular Biology of Cancer Tutorial 11 Question 1 2 3 4 5 Answer D D D B C 1 Which of the following contribute(s) towards cancer progression? 1 Activation of genes that causes cell death. 2 Inactivation of genes that slow down the cell cycle. 3 Activation of genes that result in growth of new blood vessels. 4 Inactivation of genes involved in cell-cell adhesion. A 2 only B 1 and 3 C 1 and 4 D 2, 3 and 4 2 Which of the following is not true about cancer cells? A Metastasis establishes new tumours distant from the site of the primary tumour. Metastasis establishes secondary tumours B Telomerase maintains the length of telomeres, allowing for continuous cell division. Enzyme lengthens telomeres, using a RNA template. NB: End -replication problem still occurs. C Angiogenesis forms new blood vessels and brings nutrients and oxygen to the tumour. Formation of new blood vessels also allows waste products to be carried away from rapidly dividing cells. D Cancer cells exhibit anchorage dependence . Cancer cells do not exhibit anchorage dependence, therefore they can dislodge from original tumor and und ergo metastasis.

St Andrew’s Junior College Molecular Biology of Cancer 2022 H1 Biology 2 3 The diagram represents stages in the development of a particular cancer in an adult person, over a period of 27 years. Which shows the processes happening between each of the stages indicated? stage 1 to stage 2 stage 3 to stage 4 stage 4 to stage 5 stage 5 to stage 6 A mutation proliferation mutation and proliferation mutation and proliferation B mutation mutation and proliferation proliferation mutation and proliferation C mutation and proliferation mutation and proliferation proliferation mutation D Mutation (appearance of mutated cells which look abnormal) Mutation (appearance of mutated cells which look abnormal) Proliferation (increase in number of abnormal cells) mutation (appearance of mutated cells which look abnormal)

St Andrew’s Junior College Molecular Biology of Cancer 2022 H1 Biology 3 4 It has been suggested that bre ast cancer cells produce high levels of hydrogen peroxide. This causes connective tissue cells near the cancer cells to digest some of their mitochondria, releasing nutrients which feed the cancer cells. Which observations made on breast cancer cells and connective tissue cells growing in tissue culture support this view? 1 Breast cancer cells grown alone produce hydrogen peroxide. Stated by the first sentence. 2 Treating breast cancer cells with hydrogen peroxide causes apoptosis. Question did not mention anything about apoptosis. 3 Connective tissue cells grown with breast cancer cells have reduced mitochondrial activity. Due to the hydrogen peroxide causing neighbouring connective tissue cells to digest their mitochondria (2nd sentence in the question). 4 Treating breast cancer cells with peroxidase increases cancer cell death. Peroxidase breaks down the hydrogen peroxide produced by cancer cells, resulting in less digestion of mitochondria in neighbouring connective tissue cells, hence less nutrients to feed the cancer cells. A 1, 2, 3 and 4 B 1, 3 and 4 only C 1 and 4 only D 2 and 3 only 5 Mammalian cells growing in tissue culture divide for several generations and form thin layers on solid surfaces. Growth is inhibited by cell-cell contact (contact inhibition). After the majority of cells have died, cance rous cells may remain as a resul t of changes that occurred in three stages. Immortalization  transformation  metastasis Descriptions of the cells in each of these stages are listed. 1 Cells can divide indefinitely and become mobile, migrating to form new colonies. 2 Cells can divide indefinitely and show contact inhibition. 3 Cells can divide indefinitely and do not show contact inhibition. Which row correctly describes the cells at each of these three stages? Immortalisation Transformation Metastasis A 1 2 3 B 2 1 3 C 2 3 1 D 3 2 1

St Andrew’s Junior College Molecular Biology of Cancer 2022 H1 Biology 4 Error editing: Development of cancer is a multi-step process. Occasionally, a single mutation is sufficient to transform a normal cell into a malignant cell. Some mutations may cause activation of telomere gene. Telomerase enzyme prevents end replication problem from occurring, hence preventing the shortening of the chromosome ends. As such, the cell can continue to divide indefinitely. Some mutations cause cells to lose the ability to differentiate. Some mutations cause cells to no longer exhibit anchorage dependence where the cancer cells can divide well beyond a single layer and pile up in chaotic fashion. Some mutations cause a loss of density-dependent inhibition where the cancer cells are capable of cell division in suspension as they have developed the ability to break down substances around it to create more space to grow and divide. The accumulation of mutations may result in the formation of malignant tumours. Mutations can also lead to metastasis, where there is a formation of new network of blood vessels to the cancer cells. The blood vessels provide the cancer cells oxygen and nutrients for growth and to remove any waste products. Some mutations allow for angiogenesis to occur where cancer cells are able to break loose and travel in the bloodstream and invade other tissues to form secondary tumours. At this point, the tumour is considered benign. Answer: Development of cancer is a multi-step process. Occasionally, a single mutation is not sufficient to transform a normal cell into a malignant cell. Some mutations may cause activation of telomere telomerase gene. Telomerase enzyme prevents end replication problem from occurring , (end replication problem still occurs after every round of DNA replication) elongates the telomeres using its RNA template, hence preventing the shortening of the chromosome ends. As such, the cell can continue to divide indefinitely. Some mutations cause cells to lose the ability to differentiate.

St Andrew’s Junior College Molecular Biology of Cancer 2022 H1 Biology 5 Some mutations cause cells to no longer exhibit anchorage dependence density- dependent inhibition where the cancer cells can divide well beyond a single layer and pile up in chaotic fashion. Some mutations cause a loss of density-dependent anchorage-dependent inhibition where the cancer cells are capable of cell division in suspension as they have developed the ability to break down substances around it to create more space to grow and divide. These accumulation of mutations may results in the formation of malignant benign tumours. Mutations can also lead to metastasis angiogenesis, where there is a formation of new network of blood vessels to the cancer cells. The blood vessels provide the cancer cells oxygen and nutrients for growth and to remove any waste products. Some mutations allow for angiogenesis metastasis to occur where cancer cells are able to break loose and travel in the bloodstream and invade other tissues to form secondary tumours. At this point, the tumour is considered benign malignant.

St Andrew’s Junior College Molecular Biology of Cancer 2022 H1 Biology 6 STRUCTURED QUESTIONS QUESTION 1 (9648 / 2013 / 2 / Q2) In normal cells, the cell cycle is controlled at checkpoints. In cancer, in addition to altered growth-controlling genes, many types of cancerous cells have inactivated checkpoint controls. These checkpoints involve proteins called Cyclin - Dependent-Kinases (CDKs). CDK proteins are inactive but are activated by binding to cy