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Chemistry S2 > Test 3: Energy Principals and Material Metabolism > Flashcards

Test 3: Energy Principals and Material Metabolism Flashcards

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1
Q

What is digestion? What is its function? Where does it occur? How does it occur? What is broken down into what? What is it controlled by?

A
  • breakdown of large molecules into smaller ones (hydrolysis)
  • allows nutrients to be absorbed
  • occurs in the gastrointestinal tract
  • action of enzymes, bile and hydrochloric acid

proteins –> amino acids
fats –> fatty acids, monoglycerides
starch –> glucose

  • controlled by the nervous system and hormones
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2
Q

State the different pancreatic enzymes, their substrates and digestive products.

trypsin, lipase, phospholipase, alpha amylase

A

enzyme - substrate - digestive product
trypsin - protein - smaller fragments
chymotrypsin - protein - smaller fragments
carboxypeptidase - protein - smaller fragments
lipase - fats - fatty acids & monoglycerides
phospholipase - lecithin & related compounds - free fatty acids
alpha amylase - starch - maltose & glucose

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3
Q

What is absorption? Its function? How are things absorbed?

A
  • passage of nutrients from the gut into the blood stream
  • allows nutrients to be utilized
  • active transport / passive diffusion
  • fat soluble vitamins are absorbed along fat
  • water soluble vitamins are absorbed by diffusion
  • minerals: fully absorbed (eg. Na+) or partially aborbed (eg. Cu2+, Fe2+, Ca2+, Zn2+)
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4
Q

What is metabolism? What are the two types of metabolism? What are the energy sources of metabolsim?

A
  • refers to all the chemical changes which take place in the body,
  • anabolism: syntheiss of glycogen, fat and proteins
  • catabolism: breakdown of substances
  • energy sources: amino acids, fatty acids, monosaccharides
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5
Q

How are carbohydrated digested? Into what are they tranformed? Where are they absorbed?

A

DIGESTION TYPE:
ruminant- microbial
non ruminant- enzymes (herbivorous, omnivorous, carnivorous)

DIGESTION OUTCOME:
ruminant: Volatile Fatty Acids (in rumen)
non-ruminant: Glucose (in small intestine)

FINAL ABSORPTION:
ruminant: into blood circulation
non-ruminant: into blood circulation

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6
Q

What is the digestion of carbohydrates catalysed by?

A

glycoside hydrolases (glycosidases)

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7
Q

Explain the digestion of carbohydrates.

A

CARBOHYDRATES:
- plant = starch
- animal = glycogen

MOUTH:
- alpha amylase (starch and glycogen) –> hydrolyses alpha (1-4) bonds

PANCREASE:
- pancreatic amylase (remaining poly and ogliiosaccharides) –> hydrolyses alpha (1-4) bonds
- starch & glycogen –> maltose

SMALL INTESTINE:
- sucrase
- lactase
- maltase

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8
Q

What does alpha amylase not hydrolyse? Where is it present?

A
  • alpha 1-6 bonds
  • present in: amylopectin and glycogen
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9
Q

Summarise the digestion of carbohydrates in monogastrics.

A
  • polysaccharides –> monosaccharides
  • monosaccharides taken up by active transport/ facilitated diffusion
  • monosaccharides to liver
  • glucose to cells
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10
Q

Summarise the digestion of carbohydrates in ruminants. What do ruminants not have?

A
  • microbes= fermentat fibre & starch –> energy for cells, VFA, CO2 & methane
  • VFA absorbed by host –> supplies energy for glucose synthesis
  • no salivary amylase
  • pancretic amylase for starch
  • cellulolytic bacteria (digest fiber)
  • amylolytic bacteria (digest sugars and starch)

RUMEN:
- microbes attach to fibers and secrete enzymes
- produce VFA
- digest polysaccharides, cellulose, hemicellulose

SMALL INTESTINE:
- secrete digestive enzymes
- digest carbohydrates
- absorb H2O, minerals, amino acids, glucose, fatty acids

CECUM & LARGE INTESTINE:
- fermentation of unabsorbed products
- absorption of H2O, VFA
- feces formation

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11
Q

What are fatty acids? What are their 3 basic types?

A

glucose –> VFA’s
- short chain fatty acids
- produced by microbes

3 types:
- acetic acid
- propionic acid
- butyric acid

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12
Q

What does 1 glucose molecule yield (VFA)? Describe how they are formed.

A

1) 2 acetate + CO2 + CH4 + heat
- acetyl CoA / formate –> acetate

2) 2 propionate + water
- succinate decarboxylation pathway –> propionate
- acrylate pathway: lactate –> propionate

3) 1 bytyrate + CO2 + CH4
- acetyl CoA + acetyl CoA –(butyrate kinase/acetate CoA transferase)–> butyrate

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13
Q

What are the uses of the different types of VFA’s?

A

ACETATE:
- energy
- fatty acid synthesis

PROPIONATE:
- energy
- gluconeogenic-glucose synthesis

BUTYRATE:
- energy
- rumen epithelial cells –> ketone (beta hydroxybytyrate)

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14
Q

What does the proportion of VFA’s depend on?

A

diets

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15
Q

What are the major constituents of dietary fat?

A

Triglycerides (TG’s)

smaller amounts:
- cholecterol (CH)
- cholesterol esters (CEs)
- phospholipids (PLs)
- fat soluble vitamins

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16
Q

What hormones regulate lipolysis? How do they regulate it?

What are they secreted by? Where?

A
  • cholestokinin (CCK) (activated the release of bile of the gall bladder)
  • secretin (biliary and pancreatic cells secrete NaHCO3–> neutralization of acidic chyme)

endocrine cells of the duodenum

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17
Q

What is the main function of the gallbladder?

A
  • provide bile salts and lecithin
  • emulsify fats
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18
Q

Explain the function of pancreatic lipase.

A

hydrolyses fatty acids: position 1 and 3
produces free fatty acids (FA) and 2 monoacylglycerols.

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19
Q

Explain the function of phospholipase.

A

Phospholipase (PLA2):
- releases FA from C’2
- generates phospholipids and 1 free FA

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20
Q

Explain the function of cholesterol esterase.

A
  • releases FA from cholesterol ester
  • forms CH and FFA
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21
Q

Explain lipid absorption in the small intestine.

A

Lipid digestion end products –(micelles)–> luminal cells of jejunal mucosa (diffuse through brush borders, leaving bile salts behind)

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22
Q

What happens to bile salts once they are left behind when micelles are dissociated?

A
  • return to lumen
  • incorporate highly lipophylic dietary materials and move them to the jejunal surface
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23
Q

How are short and MCFAs absorbed?

A
  • high water solubility
  • not dependent on micelles
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24
Q

How are lippoproteins classified?

A

density:
- HDL
- LDL
- VLDL (triglycerides and cholesterol)
- Chylomicron (triglycerides)

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25
How are fats transported? With what? Where?
- transported by: **Chylomicrons** (CM) (together with *free CH*, and *absorbed fat soluble vitamins*) - trasported to: **lymphatic system**
26
Explain monogastric protein digestion.
pepsinogen + HCL --> pepsin pepsin: - optimal pH -2pH - breaks peptide bonds between ttyrosine and phenylalanine amino acids - produces peptide fragments and amino acids - location: stomach
27
What amino acid groups does pepsin digest?
- phenylalanine (Phe) - tyrosine (Tyr) - tryptophan (Trp)
28
What structures does pepsin digest?
- secondary - tertiary - quartenary
29
What are the major enzymes present in the small intestine for protein digestion?
- **trypsin** (activated by trypsinogen): splits proteins into smaller peptides and single amino acids (cleaves on carboxy of **Lys** and **Arg**) - **chymotrypsin** (activated by chymotrypsinogen): splits proteins into smaller peptides and single amino acids (cleaves carboxy terminal **Phe**, **Tyr**, and **Trp**) - carboxypeptidase: splits single amino acids from the carboxyl end of proteins (removes **carboxy terminal residues**) - aminopeptidase: continues protein digestion (removes **amino terminal residues**)
30
How do proteins cross the small intestine wall?
single amino acids, dipeptides and tripeptides: absorbed free amino acids: co-transported via secondary active transport (Na+)
31
What is the principal function of the plasma membrane?
- control the passage of substances (selectively permeable)
32
What are the main macromolecules of membranes?
- lipids - proteins - + some carbohydrates
33
What is the model called created by the lipids in membranes which produce a unique physical environment?
fluid mosaic model
34
Esplain the structure of the fluid mosaic model.
- phospholipids form a bilayer - non-polar regions (tails) point inwards - polar regions (heads) point outwards - embedded proteins
35
What are the three types of amphipatic lipid aggregated which form in water?
- micelle - liposome - phospholipid bilayer
36
What does *amphipathic* mean? What is it used to describe?
- membrane lipids - one end of the molecule is hydrophillic, the other is hydrophobic -
37
What is the most abundant membrane lipid?
phospholipid
38
What two groups are phospholipids divided into?
- glycerophospholipids - shingolipids
39
State examples of glycerophospholipids.
- lecithin - cephalin
40
What is a spingolipid? Explain its structure.
- polar group and 2 non-polar tails - sphingosine (long chain alcohol & amino group) / its derivatives (long fatty acid chain) and a polar head
41
State an example of a sphingo lipids. State its composition.
sphingomyelin - amide bond b/w a fatty acid and sphingosine (18C alcohol)
42
Where is sphingomyelin present?
- plasma membranes (animal cells) - myelin (membranous sheath surrounding and insulating neuron axons)
43
What are glycosphingolipid?
monosaccharides bonded to the -OH of sphingosine - glycosidic bond | eg. cerebroside + galactose (plasma membrane)
44
What are gangliosides?
2+ monosaccharides sphingosine fatty acid | similar to cerebrosides
45
State an example of a ganglioside
GM2
46
State the common structure of a steroid.
4 fused rings: -3 cyclohexane rings - 1 cyclopentane ring
47
State the structure of cholesterol.
- 3 cyclohexane rings - 1 cyclopentane ring - methyl groups - OH attached to the steroid nucleus
48
State the main features of cholesterol.
- synthesised in the liver - obtained from food - needed for cell membranes, brain, nervous tissue, steroid hormones and vitamin D
49
Explain lipoproteins. Solubility?
- lipid + protein + phospholipid - soluble in water - classified into LDL, HDL, VLDV, Chylomicron
50
Explain the main parts of bile salts.
- synthesised in the liver - synthesized from cholesterol - stored in the gall bladder - secreted into the small intestine - have polar and non-polar regions - emulsify fats
51
Explain the main parts of steroid hormones.
- chemical messengers - produced from cholesterol - eg. sex hormones, adrenal corticosteroids
52
What molecules are produced from cholesterol?
- bile salts - steroid hormones
53
Explain the main parts of adrenal corticosteroids.
- steroid hormones - produced in adrenal glands (top of kidney) - eg. aldosterone (water+electrolyte balance); cortisone (blood sugar regulation)
54
Explain the main parts of anabolic steroids.
- derivatives of testosterone - illegally increase muscle mass - side effects: sleep disturbance, hair growth, liver damage etc.
55
Explain the main parts of prostaglandins.
- related to unsaturated fatty acids - all tissues - function: treatment of inflammatory diseases, blood pressure regulation, metabolism
56
What does aspirin do? What does that lead to?
- binds to cyclooxygenase - inhibits production of prostaglandins - reduction of inflammation and pain
57
What is *conformation*?
The spatial arrangement of atoms in a protein.
58
What are the functions of membrane proteins?
- transporters - enzymes - cell surface area - cell surface identity markers - cell-to-cell adhesion proteins - attachment to the cytoskeleton
59
What determines most of the membranes specific functions?
proteins
60
What are the two types of membrane proteins?
- integral proteins (inserted into the membrane) - peripheral proteins (top/bottom of membrane)
61
What part of the membrane is important for cell-to-cell adhesion?
membrane carbohydrates: - sort cells into tissues and organs - reject foreign cells by the immune system - recognise markers
62
What compound usually makes cell markers?
carbohydrates: - branched ogliosaccharides (< 15 monomers) - covalently bonded to lipids (glycolipids) - covalently bonded to proteins (glycoproteins)
63
Explain passive transport.
- movement of molecules through a membrane - no energy is required - concentration gradient
64
Explain diffusion.
- movement of molecules - high to low concentration
65
What is selective permeability? What allows for it?
- **integral membrane proteins** allow the cell to be selective about what passes through the membrane
66
Explain channel proteins.
- polar interior (polar molecules pass through) - ion channels: passage of ions - gated channels: opened or closed (chemical/electrical stimulus)
67
What are carrier proteins?
- carry molecules through a membrane - bind to specific molecules
68
What is facilitated diffusion?
- high --> low concentration - specific - passive - saturates when all carriers are occupied - carrier protein involved
69
What does glucose transport?
- erythrocytes - mediates passive transport
70
What is the difference between the solvent and solute?
solvent- water solute- dissolved substance
71
What is osmosis?
- water movement - high to low concentration - water moves to high solute concentration
72
In what two conformations does the glucose transporter exist as?
T1: glucose binding site exposed on the outer surface of the plasma T2: glucose binding site exposed on the inner surface of the plasma
73
What is a hypertonic solution? Hypotonic?
hypertonic: high solute concentration hypotonic: low solute concentration
74
How does osmosis move water? Toward what solution?
- through aquaporins - towards the hypertonic solution
75
How do organisms maintain osmotic balance?
- extrusion (Water ejected through contractile vacuoles) - isosmotic regulation (kepp cells in isotonic environment) - turgor pressure (plants: push cell membrane agains cell wall)
76
What is active transport?
- requires ATP - used directly/indirectly to fuel active transport - low to high - carrier proteins required
77
What are the types of carrier proteins used in active transport?
- uniporters (1 molecule at a time) - symporters (2 molecules same direction) - antiporters (2 molecules different direction)
78
What is the sodium potassium pump?
- active transport - 3 Na+ out - 2 K+ in - ATP used to change conformation of the carrier protein - affinity of the carrier protein changes allowing ions to be transferred across the membrane

Chemistry S2 (5 decks)

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