Chapter 6: Cells At Work- Cell Metabolism Flashcards
Metabolism
- all chemical reactions that take place in the cell
- made up of two different types of chemical reactions
- catabolism: where large molecules are broken down into smaller ones
- anabolism: where small molecules are built up into larger ones
- catabolic reactions release energy
- anabolic reactions require energy
- metabolism involves maintaining a balance between energy release and energy usage
Organic Compounds
- many substance involved with metabolism are organic
- have large molecules that always contain carbon
- examples of organic compounds are: amino acids, proteins, lipids and nucleic acids
- substances that don’t contain carbon are inorganic
- ## examples of inorganic compounds are: water, oxygen, carbon dioxide ( if they do contain carbon, its small amounts—- carbon dioxide)
Structure of organic compound: carbohydrate
Carbohydrates:
- Elements present- C, H, O (always twice as many H atoms as O atoms
- Basic unit- monosaccharides, disaccharides, polysaccharides
- Description:
~monosaccharides are single unit sugars (glucose, fructose, galactose)
~disaccharides are two simple sugars joined together (sucrose, maltose and lactose)
~polysaccharides are large numbers of simple sugars joined together (glycogen, cellulose, starch)
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Structure of organic compound: protein
They consist of 100+ or more amino acids
Elements present: C, H, O, nitrogen, sulphur, phosphorus
Basic unit: amino acids
Description: the bond formed between two amino acids is a peptide bond, two amino acids joined together is dipeptide, ten or more amino acids joined together is a polypeptide
Function in the body: all enzymes are proteins so therefore they assist with the chemical reactions that take place in the body
Structure of organic compound: lipid
Elements present: C, H, O, but less oxygen than carbohydrates
Basic unit: fatty acids and glycerol
Description: examples of lipids are fats stored in the body, phospholipids that are important in the cell membrane, steroids which include cholesterol and the sex hormone. Each fat molecule consists of one glycerol molecule or either one two or three fatty acid molecules.
Function in body: store energy, phospholipids which are important in cell membranes, the type of fat stored in the body is called triglyceride which is glycerol plus three fatty acids
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Structure of organic compound: nucleic acid
Elements present: C, H, O, N, P
basic unit: nucleotides (nitrogen base, a sugar, phosphate
Description: two main types of nucleic acid is ribonucleic acid and deoxyribonucleic acid. RNA consists of a single chain of nucleotides that contain ribose and DNA consists of two chains of nucleotides that contain deoxyribose
Function in the body: RNA carries info from the DNA in the nucleus to the cell which is how proteins are made and DNA genetic material in the nucleus that stores inherited information
Enzymes and metabolism
- are proteins that allow chemical reactions to take place at normal body temperature
- without enzymes reactions will be slow
- most chemical reactions require energy to get started (lighting a match)
- energy needed to get reaction started is called chemical energy
- enzymes reduce the activation energy, and allow reactions to proceed at a rate the suits the body’s requirements
- the molecules that the enzyme acts on is called the substrate
- each enzyme will combine with a specific substrate and is therefore only involved in one reaction
- this happens because the enzyme and substrate have properties that complement each other
Factors affecting enzyme activity
- the higher the concentration of enzyme, the faster the chemical reaction
- increasing substrate concentration will also increase rate of reaction
- the products of the reaction must continually be removed, otherwise the rate of reaction will slow
- temperature can influence enzyme activity
- each enzyme is sensitive to PH so it has to be the optimum PH for the enzyme to work
- co-factors that can change the shape of the active site so that the enzyme and the substrate can combine
- enzyme inhibitors such as penicillin can slow or stop enzyme activity
What is cellular respiration
- Where organic molecules are taken in as food and are broken down in the cell to release energy for the cells activity
- occurs in every cell of the body
- glucose (from breakdown on complex carbohydrates), amino acids (from protein breakdown), and fatty acids and glycerol (from lipids) can all be broken down in cellular respiration
- main food utilised in cell respiration is glucose
- respiration involves up to 20 little reactions and with each of these reactions more energy is released rather than doing it all at once
Energy from cellular respiration
- The complete breakdown of glucose to carbon dioxide and water has 60% of energy released as heat that cannot be utilised
- the heat energy is important because it keeps the bodies body temp constant
- remaining energy from cell respiration forms adenosine triphosphate ATP
Chemical energy use by the cell
- building complex molecules
- cell division and growth
- movement of cell organelles
- movement of whole cell
- maintaining cell organisation
- active transport
- transmission of nerve impulses
Synthesis
- the combining of small molecules to make large ones
(means the same as anabolism) - Synthesis requires both matter and energy: matter in the form of small molecules to be joined and energy to form the chemical bond that holds the unit together
Examples:
-In energy transfer by ATP protein is synthesised from amino acids
-glycogen molecules can be synthesised by joining two glucose molecules together
-glucose can by synthesised from lactic acid and oxygen
Nutrients
- any substance in our food that is used for growth, repair and maintaining the body
- any substance required for metabolism
- there are 6 groups of nutrient: water, carbohydrates, lipids, proteins, minerals and vitamins
Nutrient water:
- its important because its the fluid in which other substances are dissolved in
- chemical reactions in the cell occur in water and water molecules take in some part of the reaction
Nutrient carbohydrates
- main source of energy for the cell
- complex carbohydrates are broken down into simple sugars (glucose) which can then be broken down in cellular respiration to release energy
Nutrient lipids:
- important energy source
- they are broken down into fatty acids and glycerol
- glycerol can enter the glycolysis pathway and can be broken down to release energy
Nutrient proteins
- are broken down into amino acids
- amino acids can be assembled into new proteins
- the most important proteins that are made are enzymes
- enzymes control metabolism by controlling the rate at which it can happen
- can also be used as a source of energy: only if supply of carbohydrates and lipids is inadequate
Nutrient mineral:
- important because they may be a part of enzymes
- may function as co-factors for enzymes
- may be a part of ATP which is involved in metabolism
Nutrient vitamins:
- act as co-enzymes for many of the chemical reactions of metabolism
