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Biology AS > 3B - More Exchange and Transport Systems > Flashcards

3B - More Exchange and Transport Systems Flashcards

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1
Q

Give two examples of large biological molecules and the smaller biological molecules they can be broken down into

A

starch, proteins

glucose, amino acids

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2
Q

Large biological molecules in food are too big to cross cell membranes. What does this mean they can’t do?

A

This means they can’t be absorbed from the gut into the blood.

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3
Q

What happens during digestion to large biological molecules in food?

A

They are broken down into smaller molecules which can then be easily absorbed from the gut into the blood, to be transported around the body for use by the body cells.

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4
Q

Name the process that breaks down large biological molecules (in food) into smaller biological molecules

A

Hydrolysis

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5
Q

During hydrolysis, what are fats broken down into?

A

fatty acids and monoglycerides

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6
Q

During hydrolysis, what are proteins broken down into?

A

Amino acids

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7
Q

During hydrolysis, what are carbohydrates broken down into?

A

disaccharides and monosaccharides

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8
Q

What produces digestive enzymes?

A

Specialised cells in the digestive systems of mammals.

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9
Q

What happens after digestive enzymes are produced?

A

They are released into the gut to mix with food.

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10
Q

Enzymes only work with specific substrates. What does this mean for digestive enzymes?

A

Different digestive enzymes are needed to catalyse the breakdown of different food molecules.

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11
Q

What is amylase? What is its role?

A

A digestive enzyme that catalyses the conversion of starch (a polysaccharide) into the smaller sugar maltose (a disaccharide).

(this involved the hydrolysis of the glycosidic bonds in starch).

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12
Q

Where is amylase produced?

A

By the salivary glands (which release amylase into the mouth) and also by the pancreas, (which releases amylase into the small intestine).

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13
Q

What are membrane-bound disaccharidases?

where are they found?

A

Enzymes that are attached to the cell membranes of epithelial cells lining the ileum.

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14
Q

What do membrane-bound disaccharidases do?

A

They help to breakdown disaccharides into monosaccharides. This involves the hydrolysis of glycosidic bonds.

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15
Q

How are monosaccharides transported across the cell membranes of the ileum epithelial cells?

A

via specific transporter proteins

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16
Q

What do lipase enzymes do?

A

Lipase enzymes catalyse the breakdown of lipids into monoglycerides and fatty acids. This involves the hydrolysis of the ester bonds in lipids.

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17
Q

Where are lipases made?

A

In the pancreas.

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18
Q

Where do lipase enzymes work?

A

In the small intestine.

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19
Q

What is a monoglyceride?

A

A glycerol molecule with one fatty acid attached

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20
Q

Where are bile salts produced?

A

The liver

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21
Q

What do bile salts do?

A

They emulsify lipids, this means that they cause the lipids to form small droplets.

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22
Q

Why are bile salts important in the process of digestion?

A

Several small lipid droplets have a larger surface area than a single large droplet. So the formation of small droplets greatly increases the surface area of the lipid that’s available for lipases to work on.

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23
Q

What happens once a lipid has been broken down?

A

Monoglycerides and fatty acids stick with the bile salts to form tiny structures called micelles.

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24
Q

Draw a diagram showing how one large lipid droplet can become monoglycerides, fatty acids and micelles.

A

PAGE 66

=
=

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25
Q

W hat is then enzyme called that breaks down protein?

A

Protease (or peptidase)

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26
Q

Name two types of enzymes that break down protein into amino acids. (by hydrolysing the peptide bonds between amino acids)

A

Endopeptidases and Exopeptidases

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27
Q

Describe the role of Endopeptidases

A

-they act to hydrolyse peptide bonds within a protein

enDopeptidase, break bonds insiDe the protein

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28
Q

Give two examples of endopeptidases.

Where are they synthesised and secreted?

A

Trypsin
Chromotrypsin

They are synthesised in the pancreas and secreted into the small intestine

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29
Q

What is the ileum?

A

The final part of the small intestine

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30
Q

What is pepsin an example of?

A

An endopeptidase

31
Q

Where is pepsin synthesised? Where is it secreted?

A

made by cells in the stomach lining, released into the stomach.

32
Q

What conditions does pepsin work in?

A

Acidic conditions, provided by hydrochloric acid in the stomach

33
Q

Describe the role of exopeptidases

A

They act to hydrolyse peptide bonds at the ends of protein molecules. They remove single amino acids from proteins.

34
Q

What are dipeptidases?

A

They are exopeptidases that work specifically on dipeptides.

35
Q

How do dipeptidases work?

A

They act to separate the two amino acids that make up a dipeptide by hydrolysing the peptide bond between them.

36
Q

Where are dipeptidases located?

A

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

37
Q

Where are the products of digestion absorbed?

A

Across the ileum epithelium into the bloodstream

38
Q

How is glucose absorbed by the ileum epithelium?

A

Absorbed by active transport with sodium ions via a co-transporter protein

39
Q

How is fructose absorbed by the ileum epithelium?

A

It is absorbed via facilitated diffusion through a transporter protein

(a different co-transporter protein to glucose and galactose)

40
Q

How is galactose absorbed by the ileum epithelium?

A

By active transport with sodium ions via a co-transporter protein.
(The same co-transporter protein as glucose)

41
Q

How are monoglycerides and fatty acids absorbed across the ileum epithelium?

A

Micelles, help to move monoglycerides and fatty acids towards the epithelium. Because micelles constantly break up and reform they can ‘release’ monoglycerides and fatty acids, allowing them to be absorbed. Whole micelles are not taken up across the epithelium. Monoglycerides and fatty acids are lipid-soluble, so can diffuse directly across the epithelial cell membrane.

42
Q

How are amino acids absorbed by the ileum epithelium?

A

Amino acids are absorbed in a similar way to glucose and galactose. Sodium ions are actively transported out of the epithelial cells into the ileum itself. They then diffuse back into the cells through sodium-dependant transporter proteins in the epithelial cell membranes, carrying the amino acids with them.

43
Q

Some people suffer from lactose intolerance.
This can be caused by an inability to break down the lactose in the upper small intestine.
-Suggest which disaccharide enzyme is deficient or missing in people who are lactose intolerant

A

Lactase

44
Q

Some people suffer from lactose intolerance.
This can be caused by an inability to break down the lactose in the upper small intestine.
-How are the digestion products of lactose absorbed across the epithelial cells of the ileum.

A

The digestion products of the lactose/glucose and galactose are absorbed across the epithelial cells of the ileum by active transport with sodium ions via a co-transporter protein.
[2 marks]

45
Q

Where is haemoglobin (Hb) located?

A

In red blood cells

46
Q

Describe the structure of haemoglobin (Hb)

A

haemoglobin is a large protein with a quaternary structure, it’s made up of more than one polypeptide chain. (It’s actually made up of four polypeptide chains)
Each of these chains has a haem group, which contains an iron ion and gives haemoglobin its red colour.

47
Q

What does affinity mean?

A

Tendency to combine with

48
Q

How many oxygen molecules can Haemoglobin carry?

A

Four

49
Q

If Haemoglobin has a high affinity for oxygen, how many oxygen molecules would it be carrying?

A

4

50
Q

What happens to haemoglobin in the lungs?

A

Oxygen joins to haemoglobin in red blood cells

51
Q

How is oxyheamoglobin formed?

A

When oxygen combines with haemoglobin in the lungs.

52
Q

What is the reversible equation for when oxyheamoglobin is formed in the lungs?

A

INSERT PAGE 68

=
=

53
Q

There are many chemically similar types of haemoglobin found in many different organisms, all of which carry out the same function. What organisms have haemoglobin?

A

All vertebrates, Earthworms, starfish, some insects, some plants and even some bacteria.

54
Q

What does haemoglobin saturation depend on?

A

The partial pressure of oxygen

55
Q

What is the partial pressure of oxygen (PO2) a measure of?

A

Oxygen Concentration

56
Q

What causes a high partial pressure of oxygen?

A

A greater concentration of dissolved oxygen in cells

57
Q

What is the partial pressure of oxygen a measure of? (PCO2)

A

It’s a measure of the concentration of carbon dioxide (CO2) in a cell

58
Q

Haemoglobin’s affinity for oxygen varies depending on the partial pressure of oxygen.
Explain this.

A

Oxygen loads onto haemoglobin to form oxyhaemoglobin where there’s a high PO2. Oxyhaemoglobin unloads its oxygen where there’s a lower PO2.

59
Q

Explain where oxygen would load onto haemoglobin

to form oxyhaemoglobin

A

Oxygen enters blood capillaries at the alveoli in the lungs. Alveoli have a high PO2, so oxygen loads onto haemoglobin to form oxyhaemoglobin.

60
Q

Explain where/when haemoglobin would unload its oxygen

A

When cells respire, they use up oxygen, this lowers the pO2. Red blood cells deliver oxyhaemoglobin to respiring tissues, where it unloads its oxygen.

61
Q

What does haemoglobin (Hb) do once it has unloaded all of its oxygen?

A

Goes to the lungs to pick up more oxygen.

62
Q

What does a dissociation curve show?

A

How saturated the haemoglobin is with oxygen at any given point. It shows how affinity for oxygen varies.

63
Q

—- PAGE 68 GRAPH-69 GRAPHS

A

-

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Biology AS (10 decks)

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