Unit 1: Section 2 - The Digestive System Flashcards Preview

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Flashcards in Unit 1: Section 2 - The Digestive System Deck (136)
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Digestion is the process in which...............?

Large molecules are hydrolysed by enzymes to produce smaller molecules that can be absorbed and assimilated

1

Polymers are long chains of?

Monomers

2

Are protein and most carbohydrates polymers or monomers?

Polymers

3

In carbohydrates the monomers are called?

Monosaccharides

4

In proteins the monomers are called?

Amino acids

5

What elements to monosaccharides contain?

Carbon, hydrogen and oxygen

6

What elements do amino acids contain?

Carbon, hydrogen, oxygen and nitrogen

7

Which element is present only in monomers in protein?

Nitrogen

8

What's the difference between absorption and assimilation?

Absorption is when molecules move from the digestive system into the blood where as assimilation is where absorbed molecules are incorporated into body tissues

9

What's is assimilation?

Assimilation is where absorbed molecules are incorporated into body tissues

10

How does physical digestion happen in the mouth and stomach?

By the teeth in the mouth, and by the churning movement of the stomach muscles in the stomach

11

Why does physical digestion make digestion easier?

It breaks down food into smaller pieces giving a larger surface area for chemical digestion to take place on

12

What happens during chemical digestion?

Polymers are hydrolysed into smaller more soluble molecules which can be absorbed

13

How is the digestive process started in the mouth?

Teeth begin to break down the food (physical digestion) and the tongue is used to push food down the oesophagus

14

Why is saliva secreted?

Makes food easier to swallow and it contains enzymes which start chemical digestion

15

How is the digestive process continued in the oesophagus?

It takes food from the mouth to the stomach using peristalsis

16

What is peristalsis?

Wave like movements caused by contraction and relaxation of muscles, pushing food down the digestive tract

17

Why is mucus secreted in the oesophagus?

To lubricate the foods passage downwards

18

How is the digestive process continued in the stomach?

The stomach walls produce gastric juice to break down the food in the stomach (chemical digestion). Any the peristalsis of the stomach turn food into an acidic fluid called chyme

19

What do gastric juices contain?

Hydrochloric acid, pepsin and mucus

20

What are the two main parts of the small intestine?

Duodenum and ileum

21

The duodenum and ileum are parts of the?

Small intestine

22

What happens in the duodenum?

Bile and pancreatic juice neutralise the acidity of the chyme and break it down into smaller molecules

23

What happens in the ileum?

Small soluble molecules are absorbed through villi in the lining of the walls

24

What's another name for the large intestine?

Colon

25

What happens in the large intestine?

Water, salts and minerals are absorbed

26

What final part of the digestive process happens in the rectum?

Faeces are stored in the rectum and then pass through the anus on defecation

27

What is the name of the glands in the digestive system?

The salivary glands and the pancreas

28

What do the salivary glands do?

Secrete saliva

29

What does saliva contain?

Mucus, mineral salts and salivary amylase

30

What does the pancreas release into the duodenum and why?

Pancreatic juice, to provide enzymes for digestion and to neutralise the hydrochloric acid from the stomach

31

Why does the acidity of the chyme have to be neutralised?

So that the digestive enzymes can work in the small intestine

32

What enzymes are within the pancreatic juice?

Amylase, trypsin, chymotrypsin and lipase

33

What does bile contain that neutralise the stomach acid?

Sodium hydrogencarbonate

34

What three classes can digestive enzymes be divided into?

Carbohydrases, proteases and lipases

35

Carbohydrases catalyse the..........?

Hydrolysis of carbohydrates

36

Proteases catalyse the..........?

Hydrolysis of proteins

37

Lipases catalyse the..........?

Hydrolysis of lipids

38

What enzymes is produced by the salivary glands?

Amylase

39

What enzymes is produced by the stomach?

Pepsin

40

What enzymes are produced but the pancreas?

Amylase, trypsin, chymotrypsin, carboxypeptidase and lipase

41

What enzymes are produced in the ileum?

Maltese, sucrase, lactase and peptidase

42

Where is amylase produced?

In the salivary glands and pancreas

43

Where is pepsin produced?

In the stomach

44

Where is trypsin produced?

In the pancreas

45

Where is carboxypeptidase produced?

In the pancreas

46

Where is chymotrypsin produced?

In the pancreas

47

Where is lipase produced?

In the pancreas

48

Where is maltase produced?

In the ileum

49

Where is sucrase produced?

In the ileum

50

Where is lactase produced?

In the ileum

51

Where is peptidase produced?

In the ileum

52

What are four examples of a carbohydrase?

Amylase, maltase, sucrase and lactase

53

What are four examples of a protease?

Pepsin, trypsin, chymotrypsin and carboxypeptidase

54

What is an example of a lipase?

Lipase

55

Amylase hydrolysis what? into?

Starch into maltose

56

Pepsin, trypsin and chymotrypsin hydrolyse what? Into?

Protein into peptides

57

Carboxypeptidase and peptidase hydrolyse what? Into?

Peptides into amino acids

58

Lipase hydrolyses what? Into?

Lipids into fatty acids and glycerol

59

Maltase hydrolyses what? Into?

Maltose into glucose

60

Sucrase hydrolyses what? Into?

Sucrose into glucose nod my fructose

61

Lactase hydrolyses what? Into?

Lactose into glucose and galactose

62

What is a dipeptide?

When two amino acids are joined together

63

What's the difference between dipeptides and polypeptides?

Dipeptides only contain two amino acids and polypeptides contain three or more

64

What's the same general structure that all amino acids have?

A carboxyl group, and an amino group attached to a carbon atom

65

What is the difference between different amino acids ?

The variable group

66

What reaction forms polypeptides from amino acids?

Condensation reactions

67

What molecules is released during a condensation reaction?

Water

68

What are the bonds between amino acids called?

Peptide bonds

69

What's the opposite of a condensation reaction?

Hydrolysis

70

What happens during hydrolysis of polypeptide?

The peptide bond between the amino acids is broken down and a water molecules is added to form separate amino acids

71

What's the difference between hydrolysis and a condensation reaction?

In condensation reactions a water molecule is formed, hydrolysis reactions use a water molecule

72

What are the names of the different structures of protein?

Primary, secondary, tertiary and quaternary

73

What is the primary structure?

A sequence of amino acids in a polypeptide chain

74

What is a secondary structure?

Hydrogen bonds form between amino acids in the polypeptide chain causing it to coil into an alpha helix or fold into a beta pleated sheet

75

What two things do polypeptide chains from in the secondary structure?

Alpha helixs and beta pleated sheets

76

What is the tertiary structure?

The coiled or folded chain of amino acids are coiled up and folded even further, and many more bonds form between different parts of the polypeptide chain

77

Do all proteins have a quaternary structure and why?

No as some are only made up of one polypeptide chain

78

What is the quaternary structure?

Several polypeptide chains are held together by bonds.

79

Name three quaternary structure proteins?

Haemoglobin, insulin and collagen

80

Why enzymes usually spherical in shape?

Due to the tight folding of the polypeptides

81

What polypeptides are antibodies made up of?

Two light polypeptide chains and two heavy polypeptide chains

82

Why structural proteins strong?

They consist of long polypeptide chains lying parallel to each other with cross links between them making them strong

83

What test can you do to identify a protein?

Biuret

84

What is the biuret test for proteins?

1.) add a few drops of sodium hydroxide to the solution
2.) then add some copper sulfate to the solution
3.) positive results - changes to purple
negative results - solution stays blue

85

When doing a biuret test for protein why do you need to add sodium hydroxide to the solution?

To make it alkaline

86

What causes lactose intolerance?

When you don't have enough of the enzyme lactase you can't break down the lactose properly, causing lactose intolerance

87

When you have lactose intolerance what happens to the undigested lactose?

It is fermented by bacteria in the stomach causing intestinal problem

88

What intestinal problems does lactose intolerance cause?

Stomach cramps, excessive flatulence and diarrhoea

89

How does lactose intolerance cause diarrhoea?

Having a high concentration of lactose in the intestine causes water to move out of the blood into the intestines by osmosis. Meaning your faeces are more runny

90

What's another name for lipids?

Triglyceride

91

What bonds form between fatty acids and glycerol to form lipase?

Ester bond

92

What are three examples of monosaccharides?

Glucose, fructose and galactose

93

What type of bond forms between two monosaccharides?

Glycosidic bond

94

What is a disaccharide?

Two monosaccharides joined together

95

What's the difference between disaccharides and polysaccharides?

Polysaccharides contain more than two monosaccharides, disaccharides only contain two

96

What are the two forms a glucose called?

Alpha and beta

97

What reaction joins together two monosaccharides?

Condensation reaction

98

What is a general term for monosaccharides and disaccharides?

Sugars

99

What two groups can sugars be classified into?

Reducing and non reducing sugars

100

What is the test called you can do for sugars?

Benedict's test

101

What's the test you can do to find reducing sugars and what are the results?

Add Benedict's reagent and heat it
If it contains reducing sugars it will turn brick red, if no reducing sugars are present it will stay blue

102

If reducing sugars are present what do you expect to happen after the Benedict's test?

It will turn brick red

103

If reducing sugars aren't present what can you do next to see if there are any non reducing sugars?

You have to break them down into their monosaccharides by boiling it with dilute Hydrochloric acid, you then add sodium hydrogen carbonate to neutralise the solution and carry out the Benedict's test again

104

What two polysaccharides are starch made up of?

Amylose and amylopectin

105

How is starch hydrolysed into alpha glucose molecules?

Starch is hydrolysed by amylase into maltose
Maltose is then hydrolysed by maltase into alpha glucose molecules

106

What test can you do to see if starch is present?

Add iodine dissolved in potassium iodide solution
If starch is present it will change to a dark blue black colour, if no starch is present it will remain a browny orange colour

107

What's the definition of a catalyst?

A substance that speeds up chemical reactions without being used up or changed in the reaction itself

108

What are enzymes?

They are biological catalysts, catalysing metabolic reactions in your body

109

What's the part of an enzymes where the substrate binds to?

Active site

110

What is activation energy?

The minimum amount of energy that needs to be supplied to the chemicals before the reaction will start

111

Do enzymes increase or decrease activation energy?

Decrease

112

Why can enzymes lower the temperature that some reactions can happen!

The activation energy for most reactions if given as heat, as enzymes decrease the activation energy they also decreases the temperature at which a reaction will happen

113

What is it called when a substrate fits into the enzymes active site?

Enzyme - substrate complex

114

What is the reason why enzymes substrate complexes lower the activation energy when substrate molecules are being joined together?

Being binded to the enzyme holds the two substrates closer together, reducing any repulsion meaning they can bond more easily

115

What is the reason why enzymes substrate complexes lower the activation energy when substrate molecules are being broken apart?

When the substrate binds to the active site it puts a statin on the bonds in it so they can be broken more easily

116

How many models are there for how enzymes work?

Two

117

What are the names of the two models for how enzymes work?

The lock and key model
The induced fit model

118

The enzymes and substrate have a what shape?

Complementary

119

What does the lock and key model show?

The active site of the enzyme and the substrate have a complementary shape and fit together perfectly, they then bind together to form an enzyme-substrate complex. After this the substrate is released as two products. Or alternatively two substrate fit into the active site together and bond and become one product

120

What does the induced fit model show?

The active site and substrate have a similar shape and when they bind together the active site changes shape slightly so that they are now complementary, forming an enzyme substrate complex. After this the substrate is released as two products. Or alternatively two substrate fit into the active site together and bond and become one product

121

Why can enzymes only catalyse one reaction?

The shape of the active site is specific to the substrate

122

What does the shape of the active site depend on?

The enzymes tertiary structure, which is determined by its primary structure

123

Name five things that affect enzyme activity

Temperature, pH, substrate concentration, competitive and non competitive inhibitors

124

What two ways can you measure enzyme activity?

1.) measure the amount of product produced
2.) measure the amount of substrate left

125

Why does an increase in temperature increase the rate of reaction between enzymes and the substrates?

More heat means the substrate molecules have more energy and move faster, meaning they are more likely to collide with the enzymes active site, the energy of these collisions also increases more likely resulting in a reaction

126

What happens if you increase the temperature too high for an enzyme?

An increase in temperature makes the enzymes molecules vibrate more, these vibrations eventually cause the peptide bonds holding the enzyme in shape to break. This makes the enzyme and it's active site change shape so it no longer fits the substrate. Denaturing it

127

When the enzyme changes shape and can no longer catalyse the reaction it is said to be?

Denatured

128

What's the effect of a too high or too low pH on the rate of reaction between enzymes and their substrates ?

Above and below the optimum pH the H+ and OH- ions can distrust the ionic and hydrogen binds holding the enzymes tertiary structure in place, making it change shape and become denatured

129

What does an increase in substrate concentration do to the rate of reaction?

Increase it up until the saturation point

130

Why does an increase in substrate concentration cause the rate of reaction between the enzyme and substrate but only up till the saturation point?

More substrate means there will be more collisions between the substrate and active sites increasing the rate of reaction. However at saturation point all the active sites are occupied and increasing the substrate anymore won't make any difference

131

What are the molecules called that can prevent enzyme activity?

Enzyme inhibitors

132

How do competitive inhibitors prevent enzyme activity?

They have a similar shape to the substrate molecules, and compete with the substrate molecules to bind to the active site. However no reaction takes place when they do they just block it for the substrate molecules meaning they can't react

133

How much the enzyme is inhibited depends on?

The relative concentrations of the inhibitors and substrate

134

How do non competitive inhibitors prevent enzyme activity?

They bind to the enzyme away from the active site. Causing the active site to change shape so the substrate molecules can no longer bind it it

135

Will increasing the concentration of substrate make any difference to non competitive inhibitors?

No as non competitive inhibitors don't use the active sites and they will still alter the shape of the active sites