Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Topic 3A: Exchange and Transport Systems > Digestion and Absorbption > Flashcards

Digestion and Absorbption Flashcards

1
Q

Why are large biological molecules

e.g starch and proteins

in food

can’t be absorbed from the gut into the blood?

A

They are too big to cross the cell membranes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What happens during digestion?

A

Large molecules are broken down into smaller molecules (e.g glucose,amino acids)

They can move across the cell membrane and be easily absorbed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What type of reaction that large molecules can be broken down into smaller molecules?

A

Hydrolysis reaction - break bonds by adding water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Process of hydrolysis of carbohydrates:

A
  • Disschardies
  • Monosaccharides
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Process of hydrolysis of proteins

A

Proteins

Amino acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Process of hydrolysis of lipids

A

Fatty acids

Monoglycerdies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Where is the variety of different digestive enzymes?

A

Produced by specialised cells in digestive systems of mammals

These enzymes are released into the gut to mix into the food

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Why are different enzymes needed to catalyse the breakdown of food molecules?

A

Enzymes only work with specific subtrates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is amlyase?

A

Digestive enzyme that catalyses the conversation of starch (polysaccharide)

into the smaller sugar maltose (disaccharide)

This involves the hydrolysis of glycosidic bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Where is the amylase produced?

A

By salivary glands (release amylase into the mouth)

and also by pancreas (release amylase into the small intestine)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are membrane-bound disaccharides?

A

Enzymes that are attached to the cell membrane of epithelial cells lining the ileum (final part of the small intestine)

Help to break down disaccharides (e.g maltose, sucrose and lactose) into monosaccharide

Hydrolysis of glycosidic bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the disaccharidase for maltose?

A

Maltase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the disaccharidase for sucrose?

A

Sucrase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the disaccharidase for lactose?

A

Lactase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Hydrolysis of maltose

A

Alpha glucose + Alpha glucose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Hydrolysis of lactose

A

glucose + galactose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Hydrolysis of sucrose

A

glucose + fructose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How can monosaccharides be transported across the cell membrane of ileum epithelial cells?

A

via specific transporter proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What does lipase enzyme catalyse?

A

The breakdown of lipids into monoglycerides and fatty acids

Involve the hydrolysis of ester bonds in lipids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is a monoglyceride?

A

Glycerol molecule with one fatty acid attached

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Where are the lipase made?

A

In pancreas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Where do lipase work?

A

In small intestine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Where are bile salts produced?

A

In the liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What do bile salts do to lipids?

A

Emulsify lipids - cause lipids to form small droplets

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Why are bile salts so important for lipid digestion?

A

Several small lipid droplets have a bigger surface area than a single large droplet (same vol)

formation of small droplets increase SA of lipid that’s available for lipase to work on

Lipids broken down : monoglycerides and fatty acids stick to bile salts to form tiny structures called micelles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Are proteins broken down by a combination of different proteases/peptidases?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What do the combination of proteases/peptidases do to break down proteins?

A

Hydrolysing the peptide bonds between the amino acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Different types of protein enzymes

A
  • Endopeptidase
  • Exopetidases - Dipeptidases
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What does endopeptidases act?

A

Hydrolyse peptide bonds within a protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What are examples of endopeptidases?

A
  • Trypsin
  • Chymotrypsin
  • Pepsin
31
Q

What are the properties of trypsin and chymotrypsin

A
  • Synthesised in pancreas
  • Secreted into small intestine
32
Q

What is properties of pepsin?

A
  • Released into the stomach by cells in the stomach lining
  • Only works in acidic conditions - provided by hydrochloric acid in the stomach
33
Q

How do exopeptidases act?

A

To hydrolyse peptide bonds at the end of protein molecules

They remove single amino acids from proteins

34
Q

What are dipeptidases?

A

They are exopeptidases to work specifically

They act to separate the two amino acids that make up dipeptide by hydrolyzing the peptide bonds between them

35
Q

Where is dipeptidases often located?

A

In cell-surface membrane of epithelial cells in small intestine

36
Q

How is monosaccharides transported?

A
  • Glucose is absorbed by active transport with sodium ions via co-transport protein
  • Glucose is absorbed in the same way using the same co-transport protein
  • Fructose is absorbed via facilitated diffusion via different transporter protein
37
Q

How is monoglycerides and fatty acids transported across ileum epithelium into the bloodstream?

A

Micelle help to move monoglycerides and fatty acids towards the epithelium

monoglycerides and fatty acids are lipid soluble - diffuse directly across the epithelial cell membrane

Micelle constantly break up and reform so they can release monoglycerides and fatty acids allowing them to be absorbed - whole micelle not taken up in epithelium

38
Q

How are amino acids transported across the ilem epithelium into the bloodstream?

A

Amino acids are absorbed via co-transport

Sodium ions are actively transported out of ileum epithelial cells into blood

creates sodium ion concentration gradient

Na+ ions can diffuse from lumen of the ileum into the epithelial cells through sodium-dependent transporter protein , carrying amino acids with them.

39
Q

Some people suffer from lactose intolerance

This is caused by an inability to break down lactose in upper small intestine

a) Suggest which disaccharidase enzyme is deficient or missing in people who are lactose intolerant

A

Lactase

40
Q

Some people suffer from lactose intolerance

This is caused by an inability to break down lactose in upper small intestine

b) How are the digestion products of lactose absorbed across the epithelial cells of the ileum?

A

The digestion products of lactose/glucose and galactose are absorbed across the epithelial cells by active transport with sodium ions via a co=transport protein

41
Q

Where in the body would you find sucrase?

A

On the cell membrane of epithelial cells lining the ileum

42
Q

What is the role of sucrase in body?

A

Sucrase catalyses the hydrolysis of sucrose into glucose and fructose

Smaller molecules/monosacharides can be absorbed across the ileum epithelium into bloodstream

43
Q

Diagram of human digestive system labelled

A
44
Q

What is the oesophagus?

A

Carries food from the mouth to the stomach

45
Q

What is the stomach?

A

Muscular sac with an inner layer that produces enzymes

Its tole to store and digest food , especially proteins

Has glands to produce enzymes to digest proteins

46
Q

What is the ileum? (small intestine)

A

Long muscular tube

Food is further digested in the ileum by enzymes produced by its walls and glands pour secretions into it

Inner walls are folded into villi - giving a large surface area

surface area increased by microvilli on epithelial cells of each villus

Adapts for absorbing products of digestion into the bloodstream

47
Q

What is the large intestine?

A

Absorbs water

Most of the water that is absorbed from secretions of the many digestive glands

48
Q

What is rectum?

A

Faces stored in here before periodically removed by the anus in a process called egestion

49
Q

What is salivary glands?

A

Situated near the mouth

They pass their secretions via the duct into mouth

These secretions contain the enzyme amylase which hydrolyses starch into maltose

50
Q

What is pancreas?

A

Large gland is situated below the stomach

It produces a secretion called pancreatic juice

Secretion contains proteases to hydrolyses proteins

lipase to hydrolyse lipids

amylase to hydrolyse starch

51
Q

What are the two types of digestion?

A

Physical breakdown

Chemical breakdown

52
Q

What is physical breakdown?

A

If food is large

Broken down into smaller pieces by means of structure such a teeth

provides a large surface area for chemical digestion

food is churned by muscles in the stomach wall and physically breaks it up

53
Q

Explain why the stomach does not have villi or microvilli?

A

Villi and microvilli increase the surface area to speed up the absorption of soluble molecules

As food in the stomach has not yet been hydrolysed into soluble molecules they cannot be absorbed and so villi and microvilli are unnecessary

54
Q

Name the final product of starch digestion in the gut

A

Alpha glucose

55
Q

List the three enzymes produced by the epithelium of the ileum:

A

Maltase

Sucrase

Lactase

56
Q

Suggest the process by which microorganisms produce a large volume of gas in lactose intolerant individuals

A

Respiration

57
Q

Suggest a reason why a gas is unlikely to be carbon dioxide

A

CO2 is formed in aerobic respiration

whereas conditions in colon is anaerobic

58
Q

Suggest an explanation why lactose intolerance is a problem for modern day humans but wasn’t for our ancestors?

A

Modern storage and distribution methods mean that milk and milk products are readily available

Without these ancestors rarely consumed milk as adults

59
Q

Explain how the lowering of water potential in the colon cause diarrhoea?

A

Low water potential in colon causes the water to move from epithelial cells into the lumen of the colon creating watery stools

60
Q

Which process by which fatty acids and glycerol enter the intestine epithelial cells?

A

Diffusion

61
Q

Explain the advantages of lipid droplet and micelle formation:

A

Droplet increases surface area for lipase enzyme action

Faster rate of hydrolysis reaction

Micelles carry fatty acids and glycerol through the intestine epithelial cell

62
Q

Name how Golgi apparatus involved in the absorption of lipids

A

Modifies and processes triglycerides

Combine triglyceride with proteins

Form vesicles

Packaged for release/exocytosis

63
Q

Sodium ions from salt(sodium chloride) are absorbed by cells lining the gut. Some of these cells have membranes with carrier protein called NHE3.

NHE3 actively transport one sodium ion into the cell in exchange for one proton (one hydrogen ion) out of the cell

Use your knowledge of transport across cell membrane across cell membrane to suggest how NHE3 does this

A

Co-transport

Uses of hydrolysis - ATP needed

Sodium ion and protein bind to protein

Protein changes shape to move sodium ion and/or proton across the membrane

64
Q

Explain why pH decreases when the lipase is added to the milk

A

Fatty acids are produced

65
Q

Suggest why pH remained constant after 2 minutes

A

No more fatty acids are produced

All triglycerides/fat/lipids/substrate used up/enzyme denatured

66
Q

Name the part of a pancreatic cell that produces an inactive form of trypsin

A

Ribosome/ RER - rough endoplasmic reticulum

67
Q

Suggest an advantage of producing trypsin in an inactive form inside cells of the pancreas

A

Does not digest protein inside cells

So (pancreatic) cells/tissues/function does not get destroyed/damaged

68
Q

Name the type of bond hydrolysed when the short chain of amino acids is removed

A

Peptide bonds

69
Q

Sometimes trypsin can become activated inside a pancreatic cell.

A competitive inhibitor in the cell then binds to the trypsin and stops it working

Explain how the competitive inhibitor stops trypsin from working

A

Inhibitor has similar shape to the substrate

The inhibitor blocks the active site/complementary to the active side/binds to the active site of trypsin

Substrate cannot bind to active site/fewer ES complexes formed

70
Q

Surgery is sometimes carried out to remove the gall bladder.

Explain why a change in diet is required after removal of gall bladder

A

Less fat in the diet

Bile emulsifies lipids/ produces smaller droplets

Increase surface area for (action of enzyme) lipase

71
Q

Pancreatic enzyme becomes active when they reach the lumen

If the pancreatic duct becomes blocked, enzymes can become active in the pancreas

Suggest how activation of these enzymes in the pancreas can affect the pancreas

A

Protease/lipase digest (pancreatic tissue)

72
Q

Where is maltase produced?

A

Small intestine

73
Q

Where is amylase produced?

A

Pancreas

Salivary glands

Topic 3A: Exchange and Transport Systems (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions