Digestive system

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What is a polymer?
large complex molecule composed of long chains of monomers
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What are the monomers called for carbs and proteins?
carbs- monosaccharides proteins- amino acids
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Why can't polymers in our food be absorbed straight into our bloodstream?
because they're insoluble, have to be hydrolysed by adding water = soluble
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What is hydrolysis?
polymers are broken down into smaller soluble molecules by adding water
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What does the oesphagus do?
tube that takes food from mouth to stomach using waves of muscle contractions & mucus is produced to help food move downwards
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What does the small instestine do?
it has two main parts, duodenum and ileum, pancreatic juice neautalise acidity of chyme breaking it down into smaller molecules. absorbed through villi line gut wall, absorbed bye facilitated diffusion, diffusion and active transport
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What does the stomach do?
small sac, lots of folds, can expand, enterance and exit controlled by sphincter muscles, produce gastric juice helps break down food. only works in acidic conditions
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What does gastric juice consist of?
hydrochloric acid, pepsin (an enzyme) and mucus
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What does the large intestine do?
colon absorbs water, salts and minerals, folded wall = large surface area for absorption
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What does the rectum do?
faeces are stored here, pass through sphincter muscles at anus during defection
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What do glands along the digestive system do?
they release enzymes to help break down food
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What do the salivary glands do?
secrete saliva- consists of mucus, mineral salts and salivary amylase, amylase breaks down starch into maltose, helps lubricate food - easier to swallow
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What does the pancreas do?
Releases pancreatic juice into duodenum through duct, contains amylase, trypsin, chymotrysin and lipase, sodium hydrogen carbonate = neutralises acidity in stomach
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When is a dipeptide and polypeptide formed?
d- when 2 amino acids join P- more than two amino acids join
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How are amino acids linked together & monosaccharides...
condensation reactions
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Describe briefly the primary & secondary structures...
P- sequence of AA in polypeptide chain, S- doesn't remain flat, H bonds form, coils into an alpha helix or fold into beta pleated sheet
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Describe briefly the tertiary and quaternary structure...
T- coiled & folded further, more bonds form, forms final 3D structure, Q- made of several different polypeptide chains held by bonds, way they're assembled together, is final 3D structure
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What do enzymes do?
some break down large food molecules, some help to make large molecules
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What are antibodies?
involved in immune response, two light polypeptide chains and two heavy bonded together, variable reigions, sequenes vary
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What are transport proteins?
present in cell membranes, hydrophobic and hydrophilic amino acids, cause protein to fold and form a channel
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What test do you carry out to test for proteins?
The biuret test
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Name some monosaccharides...
glucose, fructrose and galactose
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What happens during a condensation reaction?
a molecule of water is released, glycosidic bond forms between two monosaccharides
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What is lactose intolerance caused by?
lack of digestive enzyme lactase
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What exactly is lactose intolerance?
if you don't have enough lactase, wont be able to break down lactose in milk, fermented by bacteria, can cause stomach cramps, wind and diarrhoea
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What test can you use to test for sugars?
Benedict's test
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What are reducing sugars?
include all monosaccharides and some disaccharides- maltose, add reagent to sample and heat, contains R sugars turns red
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What are non-reducing sugars?
Sucrose is a non-R sugar. break down into monosaccharides, boil solution w/ hydrochloric acid, neutralise, caryy out as usual, to check it's non need to do R sugar test too
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What two polysaccharides is starch made from?
Amylose and amylopectin
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What test do you carry out to test for starch?
iodine test
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What exactly is an enzyme?
A biological catalyst which speeds up chemical reactions, they are proteins and have an active site with a specific shape, specific due to their teritary structure
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Describe briefly the lock and key model...
only works with substrates which fit active site, substrate fits into enzyme in same way as a key fits into a lock
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Describe briefly the induced fit model...
substrate not only has to be right shape to fit active site, has to make AS change shape
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How do enzyme properties relate to structure?
specific, catalyse one reaction, only one substrate fits to active site, each enzyme has a different teritary structure, if it's altered then substrate wont fit and enzyme can't carry out its function, primary structure determind by a gene
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When there's more kinetic energy (heat) what are enzymes going to do?
molecules mover faster, vibrate more, which means they're more likely to collide
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What happens if the temperature gets too high?
vibration breaks some bonds, AS changes shape, enzyme and substrate don't fit together, enzyme is denatured
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What also affects enzyme activity?
pH, too high or too low results in enzyme denaturing
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What does it mean if the substrate concentration is high?
faster reaction, collision is more likely
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Describe competitive inhibition...
simular shape to substrate molecules, compete to bind to AS, and block it so no substrate can fit, HC= take up nearly all AS
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What is non competitive inhibition?
bind to enzyme away from AS, AS changes shape so sub molecules can't bind, don't 'compete' with sub molecules; different shape, increasing conc wont make difference
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Other cards in this set

Card 2


What are the monomers called for carbs and proteins?


carbs- monosaccharides proteins- amino acids

Card 3


Why can't polymers in our food be absorbed straight into our bloodstream?


Preview of the front of card 3

Card 4


What is hydrolysis?


Preview of the front of card 4

Card 5


What does the oesphagus do?


Preview of the front of card 5
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