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Biology > 3.3.3 digestion and absorption > Flashcards

3.3.3 digestion and absorption Flashcards

1
Q

give some examples of large biological molecules

A

starch, proteins

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2
Q

can large biological molecules cross the cell membrane and what does this mean can’t happen

A

large biological molecules in food are too big to cross cell membranes so they can’t be absorbed from the gut into the blood

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3
Q

what happens to these larger molecules during digestion

A

during digestion, these larger molecules are broken down into smaller molecules (e.g. glucose, amino acids)

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4
Q

can these smaller molecules move across cell membranes and what does this allow to happen

A

smaller molecules can move across cell membranes so they can be easily absorbed from the gut into the blood

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5
Q

what happens after these smaller molecules are absorbed from the gut into the blood

A

they can be transported around the body for use by the body cells

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6
Q

what are most large biological molecules

A

polymers

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7
Q

what are these larger molecules/polymers broken down into and by what process

A

broken down into smaller molecules (monomers) using hydrolysis reactions

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8
Q

what happens in a hydrolysis reaction (simplified)

A

hydrolysis reactions break bonds by adding water

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9
Q

during hydrolysis, what are carbohydrates broken down into

A

disaccharides then monosaccharides

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10
Q

during hydrolysis, what are fats broken down into

A

fatty acids and monoglycerides

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11
Q

during hydrolysis, what are proteins broken down into

A

amino acids

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12
Q

what are digestive enzymes used for?

A

digestive enzymes are used to break down biological molecules in food

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13
Q

where can digestive enzymes be produced

A

variety of digestive enzymes are produced by specialised cells in the digestive systems of mammals

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14
Q

what do these digestive enzymes mix with?

A

food

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15
Q

do different enzymes work with different food molecules?

A

enzymes only work with specific substrates so different enzymes are need to catalyse the breakdown of different food molecules

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16
Q

DIGESTION OF CARBOHYDRATES
what enzyme catalyses the breakdown of starch

A

amylase is the digestive enzyme that catalyses the breakdown of starch

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17
Q

DIGESTION OF CARBOHYDRATES
what is starch made of

A

starch is a mixture of 2 polysaccharides, each made from long chains of alpha glucose molecules

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18
Q

DIGESTION OF CARBOHYDRATES
how does amylase work

A

amylase works by catalysing hydrolysis reactions that break the glycosidic bonds in starch to produce maltose (disaccharide)

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19
Q

DIGESTION OF CARBOHYDRATES
where is amylase produced

A

amylase is produced by the salivary glands and the pancreas

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20
Q

DIGESTION OF CARBOHYDRATES
as a result of where amylase is produced, where is it released into

A
  • the mouth
  • the small intestine
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21
Q

DIGESTION OF CARBOHYDRATES
what are membrane-bound disaccharides

A

membrane bound disaccharides are enzymes that are attached to the cell membranes of epithelial cells lining the ileum (final part of small intestine)

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22
Q

DIGESTION OF CARBOHYDRATES
what do membrane-bound disaccharides help to do

A

they help to break down disaccharides into monosaccharides (involves hydrolysis of glycosidic bonds)

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23
Q

DIGESTION OF CARBOHYDRATES
examples of membrane bound disaccharides

A
  • sucrase
  • maltase
  • lactase
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24
Q

DIGESTION OF CARBOHYDRATES
disaccharide sucrose

A

sucrose (disaccharide) is broken down by sucrase into glucose and fructose (monosaccharides)

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25
Q

DIGESTION OF CARBOHYDRATES
disaccharide maltose

A

maltose (disaccharide) is broken down by maltase into glucose and glucose (monosaccharides)

26
Q

DIGESTION OF CARBOHYDRATES
disaccharide lactose

A

lactose (disaccharide) is broken down by lactase into glucose and galactose (monosaccharides)

27
Q

DIGESTION OF CARBOHYDRATES
what happens to the monosaccharides

A

monosaccharides can be transported across the epithelial cell membranes in the ileum via specific transporter proteins

28
Q

DIGESTION OF LIPIDS
what enzyme catalyses the breakdown of lipids

A

lipase enzymes catalyse the breakdown of lipids

29
Q

DIGESTION OF LIPIDS
what are lipids broken down into

A

monoglycerides and fatty acids

30
Q

DIGESTION OF LIPIDS
what does the breakdown of lipids involve

A

involves the hydrolysis of the ester bonds in lipids

31
Q

DIGESTION OF LIPIDS
where is lipase made

A

lipases are mainly made in the pancreas

32
Q

DIGESTION OF LIPIDS
where are lipases secreted

A

they are then secreted into the small intestine where they act

33
Q

DIGESTION OF LIPIDS
what do bile salts do

A

bile salts emulsify lipids - cause the lipids to form small droplets

34
Q

DIGESTION OF LIPIDS
what are bile salts produced by

A

bile salts are produced by the liver

35
Q

DIGESTION OF LIPIDS
are bile salts enzymes

36
Q

DIGESTION OF LIPIDS
how do bile salts affect surface area

A

several small lipid droplets have a bigger surface area than a single large droplet

37
Q

DIGESTION OF LIPIDS
how does increased surface area as a result of bile salts give an advantage

A

formation of small droplets increases the surface area of lipid that’s available for lipases to work on

38
Q

DIGESTION OF LIPIDS
micelles

A

once lipid has been broken down by lipase, the monoglycerides and fatty acids stick with the bile salts to form tiny structures called micelles

39
Q

DIGESTION OF LIPIDS
what do micelles help do

A

micelles help the products of lipid digestion to be absorbed

40
Q

DIGESTION OF PROTEINS
what are proteins broken down by

A

proteins are broken down by a combination of different peptidases

41
Q

DIGESTION OF PROTEINS
what are peptidases

A

enzymes that catalyse the conversion of proteins into amino acids by hydrolysing the peptide bonds between amino acids

42
Q

DIGESTION OF PROTEINS
what peptidases do you need to know about

A

endopeptidases and exopeptidases (including dipeptidases)

43
Q

DIGESTION OF PROTEINS
what do endopeptidases do?

A

endopeptidases act to hydrolyse peptide bonds within a protein

44
Q

DIGESTION OF PROTEINS
examples of endopeptidases synthesised in the pancreas

A

trypsin and chymotrypsin, synthesised in the pancreas and secreted into the small intestine

45
Q

DIGESTION OF PROTEINS
example of endopeptidase released into the stomach

A

pepsin, released into the stomach by cells in the stomach lining

46
Q

DIGESTION OF PROTEINS
what conditions does pepsin work in

A

pepsin only works in acidic conditions (HCl in the stomach)

47
Q

DIGESTION OF PROTEINS
what do exopeptidases do

A

exopeptidases act to hydrolyse peptide bonds at the ends of protein molecules

48
Q

DIGESTION OF PROTEINS
what do exopeptidases remove

A

they remove single amino acids from proteins

49
Q

DIGESTION OF PROTEINS
what are dipeptidases

A

dipeptidases are exopeptidases that work specifically on dipeptides

50
Q

DIGESTION OF PROTEINS
how do dipeptidases act

A

they act to separate the 2 amino acids that make up a dipeptide by hydrolysing the peptide bond between them

51
Q

DIGESTION OF PROTEINS
where are dipeptidases often located

A

dipeptidases are often located in the cell-surface membrane of epithelial cells in the small intestine

52
Q

what are the products of digestion absorbed across?

A

products of digestion are absorbed across the ileum epithelium into the bloodstream

53
Q

ABSORBTION OF THE PRODUCTS OF DIGESTION: MONOSACCHARIDES
how is glucose absorbed

A

glucose is absorbed by active transport with sodium ions via a co-transporter protein

54
Q

ABSORBTION OF THE PRODUCTS OF DIGESTION: MONOSACCHARIDES
how is galactose absorbed

A

galactose is absorbed in the same way as glucose using the same co transporter protein

55
Q

ABSORBTION OF THE PRODUCTS OF DIGESTION: MONOSACCHARIDES
how is fructose absorbed

A

fructose is absorbed via facilitated diffusion through a different transporter protein

56
Q

ABSORBTION OF THE PRODUCTS OF DIGESTION: MONOGLYCERIDES AND FATTY ACIDS
what do micelles help to do

A

micelles help to move monoglycerides and fatty acids towards the epithelium

57
Q

ABSORBTION OF THE PRODUCTS OF DIGESTION: MONOGLYCERIDES AND FATTY ACIDS
what do micelles constantly do which allow monoglycerides and fatty acids to be absorbed

A

as micelles constantly break up and reform they can ‘release’ monoglycerides and fatty acids, allowing them to be absorbed

58
Q

ABSORBTION OF THE PRODUCTS OF DIGESTION: MONOGLYCERIDES AND FATTY ACIDS
are whole micelles taken up across the epithelium

A

whole micelles are not taken up across the epithelium

59
Q

ABSORBTION OF THE PRODUCTS OF DIGESTION: MONOGLYCERIDES AND FATTY ACIDS
what do monoglycerides/fatty acids diffuse across

A

monoglycerides and fatty acids are lipid soluble, so they can diffuse directly across the epithelial cell membrane

60
Q

ABSORBTION OF THE PRODUCTS OF DIGESTION: AMINO ACIDS
how are amino acids absorbed

A

amino acids are absorbed via co-transport, in a similar way to glucose/galactose

61
Q

ABSORBTION OF THE PRODUCTS OF DIGESTION:
sodium ions step 1

A

sodium ions are actively transported out of the ileum epithelial cells into the blood which creates a sodium ion concentration gradient

62
Q

ABSORBTION OF THE PRODUCTS OF DIGESTION:
sodium ions step 2

A

sodium ions can then diffuse from the lumen of the ileum into the epithelial cells through sodium dependent transporter proteins, carrying the amino acids with them

Biology (17 decks)

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