Chapter 6 - Cells At Work - Cell Metabolism Flashcards
(35 cards)
What is a nutrient
A nutrient is any substance in food that is used for growth, repair or maintaining the body, that is any substance required for metabolism.
What are the six groups of nutrients?
Water Carbohydrates Lipids Proteins Minerals Vitamins
How is water a nutrient
Water is important in metabolism because it is the fluid in which substances are dissolved. Chemical reactions in the cell occur in water, and water molecules actually take in some reactions.
Why is carbohydrates a nutrient?
Carbohydrates are the main source of energy for cells. Complex carbohydrates are broken down to simple sugars, particularly glucose which can then be broken down in cellular respiration
How are lipids a nutrient?
Lipids are an important energy source.
They are broken down into fatty acids and glycerol.
Glycerol can then enter the glycolysis pathway and is broken down to release energy in a similar way to glucose.
What are proteins a nutrient?
Proteins are broken dojo into amino acids. Amino acids can be broken down into new proteins.
With regards to metabolism, the most important proteins made are enzymes.
Enzymes control metabolism by controlling the chemical reactions that occur in the body,
Proteins can also be used as a source if energy but only if the supply of carbohydrates and lipids is inadequate.
Why are minerals considered a nutrient
Minerals are important for metabolism because they may be a part of enzymes, may function as co-factors for enzymes or may be a part of substances like ATP that are involved in metabolism
Why are vitamins a nutrient
Vitamins act as co-enzymes for many of the chemical reactions of metabolism
What is metabolism?
All the chemical reactions that take place in cells, and therefore in the organism of which the cells are a part, is referred to metabolism.
*METABOLISM IS CONCERNED WITH THE MAINTAINING A BALANCE BETWEEN ENERGY RELEASE AND ENERGY UTILISATION
What are the two different types of metabolism and explain them.
Catabolism; reactions in which large molecules are broken down into smaller ones
*reactions release energy
Anabolism; reactions in which small molecules are built up into larger one
*requires energy
What are organic compounds?
Organic compounds have large molecules that always contain the element carbon
Carbohydrates, amino acids, proteins, lipids and nuclei acid
What are inorganic substances
Do not contain carbon in chemical composition or if they do they are really small molecules
CO2, water, oxygen
Carbohydrates breakdown
Carbohydrates always contain; carbon, hydrogen and oxygen. There are always twice as many hydrogen atoms as oxygen
They can be broken down into
- monosaccharides; Simple sugars or single unit sugars Eg. Glucose, fructose and Galactose
- Disaccharide; are two simple sugars joined together Eg. Sucrose, maltose, and lactose.
- polysaccharides; are large numbers of simple sugars joined together Eg. Glycogen, cellulose and starch
Breakdown of protein
Proteins always contain carbon oxygen, hydrogen and NITROGEN. And often Sulfur and phosphorus
They are made up of large numbers of smaller molecules called AMINO ACIDS. About 20 different; glycine, alanine, valine and glutamic acid.
The bond that forms between amino acids is called ‘peptide bond’.
Two amino acid joined together by a peptide is called ‘dipeptide’
10 or more amino acids joined is a ‘polypeptide’
Proteins consists of 100 or more amino acids - each chain is folded in a unique way,
Proteins are important structural materials in the body.
All enzymes are proteins, so proteins are involved in all the chemical reactions of the body.
Break down of lipids
Lipids contain carbon, hydrogen and oxygen, but much less than carbohydrates.
Examples; FATS - stored in the body as energy reserves; PHOSPHOLIPIDS; important in cell membrane
STEROIDS; including cholesterol and sex hormones
Each fat molecule consists of one molecule of glycerol and one, two or three FATTY ACID molecules
The type of fat stored in the body (and 98% of fat in foods) is TRIGLYCERIDES- glycerol plus three fatty acids
Breakdown of nucleic acid
Nucleic acids are very large molecules containing carbon, hydrogen, oxygen, nitrogen and phosphorus.
They are made of nucleotides, each which contains a nitrogen base, a sugar and a phosphate
The two main kinds of nucleic acid are RIBONUCLEIC ACID, RNA
AND DEOXYRIBONUCLEIC ACID, DNA
RNA consists of single chain nucleotides that contains sugar ribose
DNA consist of two chains of nucleotides that contain sugar deoxyribose
What are enzymes?
Enzymes are proteins that allow chemical reactions to take place at normal body temperature.
Without enzymes theses reactions theses reactions would be too slow to be any use to the body.
- enzymes reduce the activation energy needed to begin a reaction.
Eg thus when our cell ‘burn’ glucose in respiration, the reaction an occur at body temp instead of higher temp of combustion
What is activation energy?
The energy needed to get a chemical reaction started is called ACTIVATION ENERGY
- enzymes reduce the activation energy needed to begin a reaction.
Eg thus when our cell ‘burn’ glucose in respiration, the reaction an occur at body temp instead of higher temp of combustion
What is a substrate
The molecules on which an enzyme acts are called SUBSTRATE.
- enzymes are specific. Each enzyme will combine with only one particular substrate and therefore involved in only one specific reaction.
This occurs because the enzyme and the substrate have a shape and a structure that allow them to fit together. Have characteristics that are complementary to each other
Lock and key method - key = enzyme, - lock = substrate
What is the active site
The part of the enzyme molecule that combines with the substrate is called ACTIVE SITE
What is enzyme- substrate complex
When the enzyme and substrate are combined they are called enzyme substrate complex
What are the factors affecting enzyme activity? ( 7 )
- The higher CONCENTRATION of enzyme, the faster the rate of a chemical reaction. By regulating the type and amount of enzymes present, the body is able to control which reactions occur and the rate at which they proceed.
- INCREASE SUBSTRATE CONCENTRATION also increases the rate of the reaction. This occurs because there will be more substrate molecules coming into contact with the enzyme molecules. Beyond a certain concentration, however, increasing the substrate will cease to have an effect because all enzyme molecules will be fully occupied.
- The products of the reaction must be continually removed, otherwise the rate of the reaction will slow because it becomes more difficult for the substrate molecules to make contact with the temperature molecules
- Temperature influences enzyme activity. The rate of most chemical reactions increase as temperature increases. This true for enzymes but only within a limited temperature range. Because enzymes are proteins, beyond 45-50°C their structure Changes and they are inactivated. The temperature at which an enzyme works best is called optimum temperature. Usually between 30-40°C
- Enzymes are very sensitive to the pH of the medium in which a reaction is taking place. Each enzyme has a optimum pH at which it will work most effectively.
- Many enzymes require the presence of certain ions or non-protein molecule before they will catalyse a reaction; Substances such as Co-factors .
Cofactors change the shape of the active site so that the enzyme can combine with the substrate. Without the cofactors the molecule is intact but cannot function. Some cofactors are no protein organic molecules called co-enzymes. Many vitamins functions as co-enzymes - Enzyme inhibitors are substances that slow or even stop the enzyme’s activity. Inhibitors may be used by cells to control reactions so that products are produced in specific amounts. Many drugs are enzyme inhibitors Eg penicillin inhibits an enzyme in bacteria that is involved in construction of the cell wall.
What is cellular respiration?
Cellular respiration is one of the most important thing metabolic processes in any cell. It is the process by which organic molecules, taken in as food, are broken down in the cells to release energy for the cell’s activities- activities such as movement of the cell p, uptake of materials from the surroundings or production and secretion of new chemical compounds.
Draw lock key method
Enzyme + substrate -> enzyme- substrate complex -> enzyme +product
