Metabolism 1 Flashcards
what are carbohydrate metabolites used for in the body
energy source
what are Lipids metabolites used for in the body
- energy source
- membrane components
- Hormonal signalling
what are proteins metabolites used for in the body
- enzymatic catalysts
- antibodies
- hormonal signalling
- structural proteins
- contractile proteins
- gas transport
what are Nucleic acid metabolites used for in the body
information storage/transmission
what is the general formula of a carbohydrate
[C(H2O)]n
How long are monosaccharides
1 monomeric unit
How long are disaccharides
2 monomeric unit
How long are oligosaccharides
3-10 monomeric unit
How long are polysaccharides
> 10 monomeric unit
how are different number of carbon atoms in a monosaccharide called
triose (3), tetrose (4) pentose (5), hexose (6)
what is an isomer
These contain the same atoms, but bonded to each other in a different 3D arrangement
what are the three important trioses in the body
Dihydroxyacetone, L-Glyceraldehyde and D-Glyceraldehyde,
what are two important pentoses in the body
ribose and deoxyribose
how are trioses important in cellular respiration
Duringglycolysis,fructose-1,6-bisphosphateis broken down intoglyceraldehyde-3-phosphateanddihydroxyacetone phosphate.Lactic acidandpyruvic acidare later derived from these molecules
how are disaccharides formed
formed by a reaction between two mono-saccharides, which eliminates water and forms a glycosidic bond
what is sucrose made from
Glucose and fructose joined together
what is lactose made from
Glucose and galactose joined together
what is maltose made from
2x Glucose joined together
what is the breakdown product of starch or glycogen
maltose
what is the chemical structure of lactose
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what is the chemical structure of glucose
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what is the chemical structure of galactose
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what is the structure of starch
75% amylopectin
25% amylose
what is the structure of amylopectin
branched polymer of glucose (formed by α-1,4 and α-1,6 glycosidic bonds)
what is the structure of amylose
linear polymer of glucose (formed by α-1,4 glycosidic bonds only)
how do we get starch in the body
Obtained in diet from plant sources
how do we get cellulose in the body
Obtained in diet from plant sources
can we digest cellulose and why
not digestible by humans due to lack of cellulase enzyme; linear polymer of glucose
how do we get glycogen in the body
obtained in diet from animal sources
what is the structure of glycogen
extensively branched polymer of glucose
what is dextrin
Breakdown product of starch and glycogen
- branched oligomer of glucose
what are the 4 main types of biologically important lipids
- fatty acids
- triglycerides
- cholesterol
- cholesterol esters
what are fatty acids
hydrocarbon chains of various lengths – considered ‘long chain’ if >12C and ‘very long chain’ if >22C
what are the two types of fatty acids
saturated and unsaturated
what are saturated fatty acids
all carbon atoms are bonded to 4 different atoms
what are unsaturated fatty acids
unsaturated fatty acids have at least one C=C double bond
how are triglycerides made
glycerol + fatty acid
what are cis/trans stereo-isomers
molecules with the same chemical and structural formula but due to having no rotation about the double bond, have different arrangements in space
what is the significance of having more cis fatty acids in a membrane
cis fatty acids pack next to each other less closely than trans ones, so cause membranes to be more fluid
what are 2 types of modified lipids
phospholipids
glycolipids
what are phospholipids
consist of a phosphate group attached to one or more fatty acid chains via glycerol or sphingosine, which itself contains a long hydrocarbon chain
what is a glycolipid
a carbohydrate element (usually an oligosaccharide) attached to one or more fatty acid chains directly or via glycerol or sphingosine
why are phospholipids important components in cell membranes
the amphipathic (polar/non-polar) nature of phospholipids being integral to membrane structure
why are glycolipids important components of cell membranes
glycolipids important for functioning in cell surface recognition
what are two important ketone bodies in humans
acetoacetic acid and b-hydroxybutyric acid
what are ketone bodies
Small (4-carbon) fatty acids formed by oxidation of fatty acids in the liver especially during fasting
when are ketone bodies especially important
in fasting state/when there is low glucose - they become important energy substrates for the brain
what happens to ketone levels in type 1 diabetes
, excessive formation of ketone bodies by the liver can result in dangerously high concentrations in the blood
how is acetone produced in the body
Acetone is formed as a breakdown product of ketone bodies and is exhaled
Roles of lipids
- fuels
- energy storage
- transport between tissues
- structural components of cell membranes
- chemical messengers
what are essential Amino acids
AA obtained from the diet
what are non-essential Amino Acids
AA synthesised endogenously
what are the 9 essential Amino Acids
*Leucine Methionine
*Isoleucine Phenylalanine
*Valine Threonine
Histidine Tryptophan
Lysine
what are the 11 non essential amino acids
Alanine Glutamine Arginine Glycine Arparagine Proline Aspartic acid Serine Cysteine Tyrosine Glutamic acid
what is the structure of ATP
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how is ATP formed
ATP is synthesised from ADP (formation of a phosphosdiester bond) using energy released by oxidation
what is the relationship between anabolic and catabolic processes and ATP
Anabolic processes consume ATP; catabolic processes produce ATP
where is glucose used as an energy source
most tissues, obligatory for brain and RBCs
where are fatty acids used as an energy source
most tissues, but minimal in neurons as a source of energy
where are ketone bodies used as an evergy source
can be used by most tissues (except liver) important for the brain as a partial substitute for glucose when this is less available
where are amino acids used as an energy source
not used as fuels by many cell types, but are used (particularly glutamine) in fast-dividing cells e.g. enterocytes and cancer cells
why can excess glucose be stored as fatty acids but not vice versa
Fatty acids can be formed from glucose, but not vice versa
.’. glucose excess can be stored as lipid (triglycerides) but then this can only be mobilised/metabolised as fatty acid
where is triglyceride stored
White adipose tissue (internal or subcutaneous) is specialised for triglyceride storage
but excess triglyceride can be stored nto ‘ectopic’ tissues (skeletal and cardiac muscle and the liver). (pathological consequences)
where are carbohydrates (as glyogen) stored
limited.
- liver to regulate blood glucose (lasts overnight in humans)
- skeletal muscle for direct energy requirements
GLUT 1 details
substrates = Glucose,
galactose, mannose
high affinity. ubiquitous expression.
high expression in RBC and brain
GLUT 2 details
substrates = Glucose,
fructose
low affinity. in liver and pancreatic b cells
insulin sensitive
GLUT 3 details
high affinity
in brain, intestine, placenta
insulin sensitive
glut 4 details
substrate = glucose. mid-high affinity. in muscles and adipose tissue.
insulin sensitive
glut 5 details
substrate = fructose
low affinity
in intestine
insulin sensitive
