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| Question | Answer |
| Define health | According to the World Health Organisation, health is defined as the complete physical, mental and social wellbeing of a person and not just the absence of a disease or infirmity. |
| Why is health difficult to define? | Health is difficult to define because it is a relative term dependent on individual circumstances. E.g. someone with a chronic disease may consider themselves to be healthy because they are living with it, however a person without a disease may not see it this way. The definition of health is constantly changing because there are many components to it and also many views on health. |
| Define disease | Disease can be defined as any condition that adversely affects the normal functioning of any part of a living organism including mental, social and physical functioning. |
| What are the issues with defining disease? | Disease is difficult to define as the term 'normal functioning' can be used in various contexts and if taken literally, can mean, for e.g. that pregnancy is a disease as it affects the normal functioning of a human. The definition of disease can also be broad and imprecise. |
| What is a difficulty in defining health and disease in terms of the way the words are used in different contexts? | Their meaning to the general public (in every day conversation) may differ to that of scientific meanings. |
| What is the function of genes in the maintenance of health? | - Genes control protein synthesis - Enzymes = proteins (made from code of genes), which control all body processes necessary for the normal functioning of a human body. - If genes = mutated, enzyme function = disrupted, cells will die out. - Proteins are necessary for the: repair, reproduction of cells, control of growth of cell and regulation of cell cycle. |
| What is the function of mitosis in the maintenance of health? | Mitosis: process of cell division by which identical body cells are produced to allow for: - growth - repair of cells which are damaged - replacement of cells which are worn out - Genetic stability: equal distribution of chromosomes in each daughter nucleus = all resulting cells have same number/kind of chromosomes as each other and parent |
| What are the two types of genes which control mitosis? | 1) Proto-oncogenes: stimulates cell division and growth. 2) Tumour suppressors: stops/slows down cell division and growth. |
| In terms of proto-oncogenes and tumour suppressors, for a healthy organism, what should be the ratio of these genes present? What are the implications of damage to these genes? | These two genes should be balanced in a healthy organism and if either of the genes mutate or are damaged, it can result in cancer due to uncontrollable cell replication. |
| Define cell differentiation and cell specialisation. | Cell differentiation: when cells mature and take on different structural features to become structurally suited for a particular function in the body. Cell specialisation: when specific genes are 'switched on' for a certain function in the body. |
| What type of organisms need specialised cells, for what purposes? Provide examples of specialised cells. | Multicellular organisms need specialised cells to carry out certain functions and maintain health. E.g. of specialised cell = RBCs, WHCs, neurones, muscle cell, bone and epithelium. |
| > Syllabus dot point: Use available evidence to analyse the links between gene expression and maintenance and repair of body tissues | :) |
| What do enzymes control? | Cellular metabolism |
| True or false: Enzymes are a type of protein | True |
| What are proteins (specifically enzymes) made up of? | Polypeptides |
| What is responsible for the production of polypeptides? | Genes |
| Therefore if enzymes control cellular metabolism, and enzymes are proteins made of polypeptides. Genes produce these polypeptides. Now, what would happen if the information in a gene is damaged or not expressed? | Information of a gene: controls the production of an enzyme, = not expressed = disrupted cellular metabolism = lack of maintenance of health and repair in body = impaired health. |
| Again, to refresh your memory: What are the two types of genes which control mitosis (cell division, growth and repair)? | 1) Proto-oncogenes 2) Tumour suppressor genes |
| What do proto-oncogenes do (in some detail)? | - Stimulate cell division and growth - code for proteins which are involved in the promotion of cell differentiation (process whereby cells mature and become structurally suited for a specific function) and cell division. - Speed up cell division |
| What are mutated proto-oncogenes called? | Oncogenes |
| What do tumour suppressor genes do? (in some detail? | - Restrict/slow cell division and growth - Code for proteins which restrain cell growth |
| What happens if tumour suppressor genes are mutated? | - In the case of mutation -- these proteins (which restrain cell division) decrease activity, hence allowing for uncontrollable cell replication = CANCER |
| True or false: A mutation in the proto-oncogene can cause cancer. | False. It's not usually enough to cause cancer, mutation needs to occur in the TS gene and many mutations sometimes need to happen for cancer. |
| Provide an example of a cancer due to mutation: | Childhood cancer: retinoblastoma To remember: retino-BLA-stoma - TS suppressor gene inactivated - Protein coded for not made therefore, unchecked tumour develops. |
| What happens without DNA repair genes, or if they are damaged? When can DNA repair genes be damaged? | - Serious diseases - Damaged during cell replication ('S' stage of cell cycle) |
| Suggest some requirements then, for a healthy body in terms of genes and cell division: | - Cells with specialised functions should be working - Malfunctioning = repaired by mitosis - Control of cell division |
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