enzymes - biological catalysts Flashcards
define active site (2)
- indented area on the surface of an enzyme molecule , with a shape that is complementary to the shape of the substrate molecules
define a catalyst (2)
- chemical that speeds up the rate of reaction and remains unchanged and reusable at the end of the reaction
what does extracellular mean ?
- outside of the cell
what does intracellular mean ?
- inside the cell
define metabolism/metabolic
- the chemical reactions that take place inside living cells or organisms
define product
- molecule produced from the substrate molecules , by an enzyme catalysed reaction
define substrate
molecule that is altered by an enzyme - catalysed reaction
what does the structure of an enzyme enable ?
- enables them to carry out their functions
for some enzymes to catalyse they may need help from ?
cofactors
what does ‘encode’ mean ?
- writing/ representing information in a specific way by following certain rules or instructions
where are the instructions for enzymes encoded ?
in genes
what happens if a gene has a mutation and it alters the sequence of amino acids (in terms of enzymes) ?
- this may alter the enzyme’s tertiary structure and prevent it from functioning
how does a metabolic disorders result ?
- due to an enzyme catalysing defictly (insufficiently) in a metabolic reaction
give examples of what enzymes catalyse (in terms of an organism’s structural components) ( LIST 4)
- collagen in bone
- cartilage
- blood vessel walls
- joints and connective tissue
why are enzymes called biological catalysts ?
as they speed up metabolic reactions in living organisms
what does enzyme action effect ?
- both structure and function within cells,tissues and organs
what can a small amount of catalyst do ?
can catalyse the changing (conversion) of large number of substrate molecules into product molecules
what is the turnover number ?
- the number of reactions that an enzyme molecule can catalyse per second
what is the difference between biological catalysts and chemical catalysts ? (3)
- BC= enzymes , highly specific, work in living organisms , operate at body temperatures
- CC= inorganic substances , less specific , work in non-living systems , often operate under extreme conditions
biological catalysts are able to
- function in conditions that sustain life
what do enzymes not do ?
- produce unwanted by-products and rarely make mistakes
what can cells that enzymes are made of do ? (2)
- regulate production of enzyme and activity to fit the needs of the cell or organism at the time
what does the active site consist of ?
- about 6-10 amino acids
why is the tertiary structure of an enzyme crucial ?
- as its shape is complementary to the shape of the substrate molecule
why is each enzyme highly specific in its function ?
- as it can only catalyse a reaction involving the particular type of substrate molecule that fits into its active site
how can the shape of the enzyme’s active site be altered ?
- by changes in temperature and pH which affects the bonds that hold proteins in their tertiary structure
what is the active site part of ?
- the enzyme molecule
where does enzymes catalyse ?
- in a wide range of intracellular and extracellular reactions
within an organelles there could be …?
- up to 1000 metabolic reactions going on at the same time
- each being catalysed by a different enzyme
what are some reactions going to be part of ?
metabolic reactions
what are catabolic reactions ?
these are reactions that break down complex molecules into simpler ones
what are anabolic reactions ?
these are reactions that join smaller molecules together to much larger/much complex ones
what does catabolic reactions do with energy and why ?
- releases energy because breaking down molecules often frees up stored energy
what does anabolic reactions do with energy and why ?
- they require energy to make new larger molecules
what is a metabolic pathway ?
- each step is catalysed by a different enzyme
- if one of the enzymes cannot function then the metabolic pathway cannot tun
what are examples of complex metabolic pathways ?
- respiration + photosynthesis
what type of proteins are enzymes ?
globular proteins
what type of shape does enzymes have ?
3 - dimensional shape
where is catalase found ?
in nearly all living organisms that are exposed to oxygen
why is catalase a very important enzyme ?
- as it protects cells from damage by reactive oxygen by quickly breaking down hydrogen peroxide
what is hydrogen peroxide ?
-a potentially harmful by-product of many metabolic reactions –> to water and oxygen
what does catalase consist of ?
4 polypeptide chains and contain a haem group with iron
how is catalase a faster-activity enzyme ? (2)
- as it has the highest turnover number known of 6 million per second
where is catalase found in a eukaryotic cell ?
in small vesicles called peroxisomes
why does WBC use catalase ?
- to help kill the invading microbe
what is optimum pH for human catalase ?
pH 7
what is the optimum pH for other species ?
between pH4 and 11
what is optimum temperature for human catalase ?
45 degrees celsius
what is optimum temperature for other species ?
- thermophillic archae is 90 degrees celsius
where are many enzymes secreted in our digestive system ?
into the gut lumen
what happens while the enzymes are secreted ?
- they extracellular digest the large molecules
–> ( proteins,lipids,carbohydrates and nucleic acids) found in food
what happens to the products of digestion ?
- they are reabsorbed –> via epithelial cells of the gut wall–> into the bloodstream in order to be used for respiration , growth and tissue repair
where is amylase produced ?
in the salivary glands
where does amylase act and why ?
- in the mouth to digest the polysaccharide starch to the disaccharide maltose
where is amylase made and what does it do ?
- in the pancreas and acts to catalyse the same reaction in the lumen of the small intestine
where is trypsin made ?
in the pancreas
where does trypsin act and why ?
acts in the lumen of the small intestine to digest proteins into smaller peptides by hydrolysing peptide bonds
what is the optimum pH of trypsin ?
- between 7.5 and 8.5
