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biology > Unit 1- Section 2 The Digestive System > Flashcards

Unit 1- Section 2 The Digestive System Flashcards

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AP® Biology flashcards
0
Q

Give 2 examples of polymers

A

Proteins and carbohydrates

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1
Q

What are polymers?

A

Long chains of monomers

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2
Q

In carbohydrates what are the monomers called?

A

Monosaccharides

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3
Q

In proteins what are the monomers?

A

Amino acids

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4
Q

What elements are in carbohydrates?

A

Carbon, hydrogen and oxygen

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5
Q

What are the elements of proteins?

A

Carbon, hydrogen, oxygen and nitrogen

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6
Q

What are the two types of digestion?

A

Physical and chemical

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7
Q

What happens during physical digestion?

A

Food is broken down into smaller pieces by the teeth in the mouth, it then moves down into the stomach where it is further broken down by churning. Breaking food down into smaller pieces gives it a large resurface area which makes chemical digestion faster

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8
Q

What happens during chemical digestion?

A

The polymers in our food are insoluble- they cannot be directly absorbed into our blood stream and made into new products.

The products have to be hydrolysed (broken down) into smaller, more soluble products by adding water. The process happens during chemical digestion.
Hydrolysis is catalysed by digestive enzymes.

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9
Q

What happens during hydrolysis?

A

Polymers are broken down into monomers by adding water

They go from being insoluble to soluble

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10
Q

What is the mouth used for when considering digestion?

A

Teeth are used to physically breakdown food
Tongue is used to force food down into the oesophagus
Saliva contains amylase enzymes that break down food and starts off the chemical digestion process it also makes food easier to swallow

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11
Q

What is the oesophagus used for when considering digestion?

A

It’s the tube that takes food from the mouth to the stomach. It does this by having waves of muscle contraction. Mucus is also secreted from the tissues in the walls to lubricate food passing downwards

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12
Q

What is the stomach used for when considering digestion?

A

Produces hydrochloric acid, pepsin and mucus to break down the food and make acidic conditions. It also churns food to physically break it down

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13
Q

What is the small intestine used for when considering digestion?

A

Bile is produced in the pancreas then is used to neutralise the acidic conditions from the stomach. Passes food to the large intestine. Soluble molecules are absorbed through villi and micro villi

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14
Q

What 3 ways is food absorbed into the small intestine?

A

Diffusion, facilitated diffusion and active transport

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15
Q

What does the large intestine do when considering digestion?

A

Absorbs water, salts and minerals. It has folded walls so provides a large surface are for maximum absorption. Bacteria and undigested nutrients are found in the large intestine

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16
Q

What does the rectum do when considering digestion?

A

Faeces are stored in the rectum and then it’s passes to the anus for defecation

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17
Q

What glands are used for digestion?

A

Salivary glands, the pancreas

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18
Q

How do the salivary glands help with digestion?

A

They secrete saliva that consists of mucus, mineral salts and salivary amylase.

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19
Q

What does salivary amylase break down and what into?

A

Breaks down starch into maltose, a disaccharides.

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20
Q

How does the pancreas help digestion?

A

Produces pancreatic juice which contains amylase and lipase. Also contains sodium hydrogen carbonate which neutralises the acidity of the hydrochloric acid from the stomach

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21
Q

What does pepsin break down and where is it found?

A

Stomach, is a protease so it breaks down protein into peptides

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22
Q

What does maltase break down?

A

Maltose into glucose

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23
Q

What digestive enzymes break down food?

A

Amylase breaks down starch into maltose

Maltase then breaks down maltose into glucose

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24
Q

What are proteins made from?

A

They are made from amino acids

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25
Q

Monomers are made from?

A

One amino acid

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26
Q

What are dipeptides made from?

A

Two amino acids

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27
Q

What are polypeptides made from?

A

More than 2 amino acids

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28
Q

What are proteins made up of?

A

One or more polypeptides

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29
Q

What is the structure of the amino acids?

A

All amino acids have the same general structure

A carboxyl group (-COOH)
Amino acid group (-NH)
2

The difference from amino acids is the variable group R

        R

H2N—C—COOH

        H
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30
Q

What is the polypeptide formation?

A

Amino acids are linked together by condensation reactions to form polypeptides
A molecule of water is released during the reaction.
The bonds formed between the amino acids are called peptide bonds

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31
Q

During condensation what bonds form between what?

A

Peptide bonds between amino acids

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32
Q

What are the four layers of a proteins structure?

A

Primary structure
Secondary structure
Tertiary structure
Quaternary structure

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33
Q

What is the primary structure of a protein?

A

Sequence of amino acids in the polypeptide chain

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34
Q

What is the secondary structure of the protein structure?

A

The polypeptide chains do not remain flat and straight. Hydrogen bonds form between the amino acids in the chain and this automatically makes it coil into an alpha helix of fold into a beta pleated sheet

35
Q

What is the tertiary structure of a protein?

A

The coiled or folded chain of amino acids is often coiled and folded further. More bonds form between the different parts of the polypeptide chain. For proteins made of one single polypeptide chain,the tertiary structure forms their final 3D structure

36
Q

What is the quaternary structure for a protein?

A

Some proteins are made up of several polypeptide chains held together by hydrogen bonds. The quaternary structure is the formation of all of these chains assembled together. This is the proteins final 3D structure

37
Q

What’s the shape and function of enzymes?

A

Rough spherical shape due to tight folding of the polypeptide chains.
They are soluble and often have roles in metabolism

38
Q

What is the shape and function of antibodies?

A

Antibodies are involved in the immune response. They’re made up of toe light and short polypeptide chains and two heavy long polypeptide chains bonded together. Antibodies have variable regions, the amino acid sequences in these regions vary greatly.

39
Q

What is the shape and function of transport proteins?

A

These are presents in cell membranes, they contain hydrophobic and hydrophilic amino acids, which cause the protein to fold up and form a channel. These proteins transport molecules and ions across membranes

40
Q

What is the shape and function of structural proteins?

A

They are physically strong, consist of long polypeptide chains lying parallel to each other with cross links between them. Structural proteins include keratin and collagen. Collagen have 3 polypeptide chains tightly coiled together, which makes it strong. It is a great supportive tissue in animals

41
Q

What does the biuret test for?

A

Proteins

42
Q

Explain the biuret test

A

Add a few drops of sodium hydroxide solution
Then add copper sulfate solution

If a protein is present the solution will turn purple, if there is no protein it will stay blue

43
Q

What are carbohydrates made from?

A

They are polymers, made up of monomers that are made of monosaccharides

44
Q

What type of sugar is glucose?

A

Hexose sugar

It is a monosaccharide with six carbon atoms in each molecule. There are two forms of glucose, alpha and beta glucose.

45
Q

How are monosaccharides joined together by, what reaction?

A

Condensation reaction

46
Q

What is released during a condensation reaction?

A

Water and a glycosidic bond is formed

47
Q

How is a disaccharide formed?

A

Two monosaccharides join together

48
Q

How is a polysaccharide formed?

A

More than two monosaccharides join together

49
Q

What happens during the digestion of carbohydrates?

A

Disaccharides and polysaccharides are broken down by enzymes.

This process is called hydrolysis

50
Q

What is maltose hydrolysed by and what is formed?

A

It is hydrolysed by maltase and it is is broken down into glucose and glucose

51
Q

What is sucrose hydrolysed by and what is it broken down into?

A

It is hydrolysed by sucrase and it is broken down into glucose and fructose

52
Q

What is lactose hydrolysed by and what is it broken down into?

A

Hydrolysed by lactase and it broken down into glucose and galactose

53
Q

What is lactose intolerance?

A

Lactose is a sugar found in milk, it is digested by the enzyme lactase that is found in the intestines. If you do not have enough of the enzyme then you will not be able to break down the lactose in milk properly.

Undigested lactose is fermented by bacteria and can cause lots of intestinal problems such as cramps, flatulence and diarrhoea.

54
Q

How can lactose intolerance people still drink milk

A

The milk can artificially be treated with purified lactase to make it suitable for lactose intolerant people

55
Q

What does the Benedict’s test test for?

A

Sugars

Non reducing and reducing

56
Q

What are reducing sugars?

A

Sugars that contain all monosaccharides and some disaccharides, for example, maltose

57
Q

How do you test for reducing sugars?

A

Add Benedict’s solution
If reducing sugars are present then it will turn a brick red
If reducing sugars are not present then it will stay blue

58
Q

How do you test for non-reducing sugars?

A

First you compete the reducing sugars test by adding Benedict’s solution, if this turns out negative (blue) then you test for non-reducing sugars

You get a new sample and boil it with hydrochloric acid
You then neutralise it by adding sodium hydrocarbonate
Finally you carry out the Benedict’s test again by adding Benedict’s solution, if it turns brick red then non-reducing sugars are present.
If it stays blue then non-reducing sugars are not present

59
Q

How is starch broken down?

A

Starch is broken down by amylase into maltose
Maltase then breaks down maltose into glucose

Amylase is secreted from the salivary glands and pancreas
Maltase is secreted from the intestinal epithelium

60
Q

What does the iodine test test for?

A

Starch

61
Q

What happens during the iodine test

A

You add bromine solution or potassium iodine solution and if it turns dark blue/black then starch is present

62
Q

What do enzymes act as?

A

Biological catalysts

63
Q

How can enzymes speed up a reaction?

A

Being a biological catalyst, they catalyse reactions in your body.

Enzymes are proteins and have an active site which has a specific shape

64
Q

What fits into the active site

A

Substrate, it is complementary. Enzymes are highly specific due to their tertiary structure

65
Q

How can enzymes speed up a reaction?

A

They lower the activation energy, which makes reactions happens at lower temperatures.

66
Q

What forms when a substrate fits into the enzymes active site?

A

It forms a enzyme-substrate complex

67
Q

What lowers the activation energy and why

A

Enzyme-substrate complex

If two Substrate molecules need to be joined, being attached to the enzyme holds them close together, reducing any repulsion from the molecules so that they can bond more easily

Of the enzyme is catalysing a breakdown reaction, fitting into the active site puts a strain on bonds in the substrate so the substrate molecule breaks up more easily

68
Q

What are the two models of enzyme action?

A

The ‘lock and key’ model and the ‘induced fit’ model

69
Q

What happens during the lock and key model?

A

The substrate fits into the active site of the enzyme the same way a key fits into a lock. They have a complementary shape to each other.

70
Q

Why did scientists have problems with the lock and key model?

A

The enzyme and the substrate do fit together but new evidence has shown that the enzyme-substrate complex changed shape slightly to complete the fit. This locks the substrate even more tightly to the enzyme. Scientists then modified this model and created the induced fit one

71
Q

What occurs in the induced fit model

A

It shows why enzymes are so specific and why they only bond to one specific substrate. The substrate has to fit into the active sight perfectly and it also has to change the active site shape slightly in the correct way. This idea is widely accepted

72
Q

What are enzyme properties?

A

Enzyme properties are related to their tertiary structure. Enzymes are very specific and only catalyse one reaction. This is because only one substrate fits into each active site

Each different enzyme has a different tertiary structure and so has a different shaped active site. If the substrate does not fit then the reaction will not be catalysed

73
Q

What is the enzymes active site determined by?

A

Tertiary structure, which is determined by the enzymes primary structure

74
Q

What happens if the tertiary structure is changed?

A

The shape of the active site will change meaning the substrate will no longer fit into the active site so the enzyme will no longer be able to carry out it’s function.

75
Q

What two factors can affect an enzymes structure?

A

Temperature and PH

76
Q

What is the primary structure of a protein determined by?

How can this affect the structure of an enzyme?

A

A gene, so if this mutates this can also change the tertiary structure of an enzyme

77
Q

What are the two ways you can measure rate of reaction?

A

Measure the amount of product produced and measuring the amount of substrate formed

78
Q

Explain how you can measure the amount of product produced and how this can help you to measure the rate of reaction

A

There are different molecules at the start to the end of the chemical traction so if you measure the amount of product at the end then the reaction rate can be calculated

79
Q

How can measuring the substrate left can lead to calculating the rate of reaction?

A

To produce the end product of a reaction, substrate molecules have to be used up. By measuring the amount of substrate left at different times in the experiment the reaction rate can be calculated

80
Q

How can temperature affect enzyme activity?

A

At low temperatures the substrate fits into the active site but does not occur quickly because there is less energy

At higher temperatures the enzyme vibrates more so this breaks some of the bonds that holds it’s shape. The added kinetic energy means that the collision rate increases so more enzyme substrate complexes form so this increased reaction rate

If the temperature increases too much the active site changes and the substrate can no longer fit. The enzyme is denatures and it no longer functions as a catalyst

81
Q

Does every enzyme have an optimum temperature?

A

Yes

82
Q

How can PH affect a enzymes activity?

A

All enzymes have an optimum PH value.
Above or below the optimum PH value means that it affects the ionic and hydrogen binds that holds the enzymes tertiary structure in place. The enzyme then becomes denatures and the active site changes shape so enzyme-substrate complexes no longer work

83
Q

How can substrate concentration affect enzyme activity?

A

The higher the substrate concentration, the faster the reaction

More substrate molecules means a collision between the active site and substrate is more likely and so more active sites will be used.

This is only true up to a saturation point, after that all of the active sites are filled up so adding more substrates would make no difference

84
Q

What two enzyme inhibitors can occur?

A

Competitive and non competitive inhibitors

85
Q

What happens with a competitive inhibitor?

A

Competitive inhibitor molecules have a similar shale to the substrates, they compete with substrate molecules to bind to the active site. When they have attached to the active site no reaction takes place, instead they block the active site so no substrate can fit in.

How much the enzyme is inhibited depends on the concentrations of the competitive inhibitors and substrates. If there is more of one than that one is more likely to bind to the active site

86
Q

What is a non-competitive inhibitor?

A

They bind to the enzyme away from its active site, this changed the shape of the active sure is that the substrate can no longer bind

They don’t compete with the substrate molecules because they bind to another site which distorts the active site. Increasing the concentration of substrate will not make any difference, enzyme activity will still be inhibited

biology (13 decks)

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