Sugar transport, metabolism, and glycolysis Flashcards
which starch is branched and soluble?
amylopectin
which starch is not branched and insoluble?
amylose
what general enzyme breaks down starch?
alpha-amylase
how does alpha-amylase act as an endoglycosidase?
it cleave polysaccharide chains between residues that are not the terminal residue, so it breaks internal bonds
which bond specifically dose alpha-amylase break?
1-4-alpha glycosidic bonds
what kind of carbohydrates does alpha-amylase mainly produce?
di- and trisaccharides
what two places does alpha-amylase reside in the body?
made by pancreas, also appears in saliva
what enzyme complex breaks down di- and trisaccharides?
sucrase-isomaltase complex
how many enzymatic activities does the sucrase-isomaltase complex have and what are they?
3 - 1-4-alpha, 1-6-alpha, and alpha-1-beta-2 glycosidic bonds
what is the end product made by the sucrase isomaltase complex?
monosaccharides, mostly fructose and glucose
where in the body does the sucrase-isomaltase complex mostly reside?
in the intestinal brush-border membrane
describe an alpha sugar
a sugar that has the -OH group and the -CH2OH group on opposite sides of the ring
describe a beta sugar
a sugar that has both the -OH group and the -CH2OH group on the same side of the ring
fructose + glucose = ?
sucrose
what breaks down sucrose?
sucrase
matlose = ___ + ____
glucose + glucose
what breaks down maltose
maltase
describe a non-reducing sugar
has both anomeric carbons bonded to the same O, has a formation of C-O-C-O-C-O-C
describe a reducing sugar
one anomeric carbon is bonded to the O joining the 2 sugars, but not the other, forms C-O-C-O-C-C
what process happens to form an inverted sugar
a hydrolysis reaction or degradation by invertase where the optical rotation changes from + to -
what kind of bond does lactase break?
the beta-glycosidic bonds in lactose
what are the components that lactose are broken down into by lactase?
glucose and galactose
what kind of bond does trehalase break?
an alpha-1-alpha-1 glycosidic bond between two glucose moecules
what components is trehalose broken down into by trehalase?
2 glucose molecules
what is the literal meaning of acarbose?
no carbs
what is acarbose?
it is a competitive inhibitor of alpha-glucosidases
what two enzyme and complex do acarbose compete with?
alpha-amylase and sucrase-isomaltase complex
where is acarbose active in the body?
the intestine
acarbose is used in the treatment of what disease?
type II diabetes
what are the 4 cross-membrane transport mechanisms?
simple diffusion, facilitated diffusion, active transport, and phago/pinocytosis
which of the 4 cross-membrane techniques are used to bring glucose into cells?
all 4 - simple diffusion, facilitated diffusion, active transport, and phago/pinocytosis
another term for facilitated diffusion is?
facilitated transport
what 4 components in the cellular barrier make it difficult for glucose to get across the BBB?
tight junctions, narrow intracellular space, lack of pinocytosis, and a continuous basement membrane
what 5 components in the cellular barrier are used for the transport of glucose across non-neuronal cells?
paracellular (b/c 1- no tight junction and 2 - wider intracellular space 3 - discontinuous basement membrane) 4- pinocytosis, and 5 - specific glucose transporters
what is the only way that glucose can pass through both neural and non-neural cells?
specific glucose transporters
what are the two types of transporters involved in glucose transport though the membrane?
active co-transporter and facilitated transporter
what kind of transporter is the active transporter that is used to get glucose across the cell membrane?
sodium-glucose symport
what pump does the active sodium-glucose transporter rely on?
the Na/K-ATPase pump
can the active sodium-glucose transport move glucose against the gradient?
yes
what is the facilitated glucose transport activated by?
insulin
what process is triggered by insulin in the facilitated glucose transporters?
phagocytosis
what kind of transporter is the facilitated transporter used to get sodium across the cell membrane?
glucose uniport
is the GLUT1 transporter a facilitated or active transport mechanism?
facilitated
all GLUT transporters are what kind of transporters?
facilitated!
the GLUT1 transporters can uptake what 2 things?
glucose and Vitamin C
where is the GLUT1 transporter most expressed?
in erythrocytes (RBC) and barrier tissue cells (like endothelial cells, eg. BBB)
which GLUT transporter is found din the liver, pancreas, small intestines, etc…?
GLUT2
which GLUT transporter is found in adipose and muscle tissue?
GLUT4
is the active transport of glucose insulin dependent?
no, it is dependent upon the Na/K ATPase pump to create a gradient
in the facilitated transport of glucose what is exchanged for 1 glucose?
2 sodium
why is it so important to bring glucose into our cells?
to fuel to cell it’self and its processes, (this answer could be explained more drawn out)
Can glycolysis occur in every cell type or just specific types?
every cell type
where in the cell does glycolysis occur?
in the cytoplasm
does glycolsis require O2?
no
what does glycolysis provide alongside it’s end product and generation of ATP?
high energy phosphate intermediates suitable for substrate level phosphyrlation
what 3 things does glycolysis produce and how much of each?
2 ATP, 2 NADH/H+, and 2 pyruvate
what is pyruvate reduced to in anaerobic cells?
lactate
what cells are under anaerobic conditions?
erythrocytes and heavily exercised muscle cells
what is regenerated when anaerobic cells reduce pyruvate to lactate?
NAD+
glycolysis generates provides pyruvate to act as a precursor for what in liver and adipose tissue?
lipid biosynthesis
what two things regulate glycolysis in liver and adipose tissue?
glucagon and insulin
glycolysis provides precursors for some of what two things?
amino acids and pentoses
how many phases are in the preparative phase of glycolysis?
3
how many ATP are consumed in the preparative phase of glycolysis?
2 ATP
how many ATP are generated in the ATP-generating phases of glycolysis?
4 ATP
what happens to all intermediates in glycolysis?
phosphorylation
Why are all intermediates in glycolysis phosphorolated?
it labels the compounds as intermediates of glycolysis as to not be used for other processes in the cell
what does hexokinase do?
phosphorylates glucose and uses 1 ATP
where is glucose phosphorylated and why?
at the 6-position because the primary alcohol has the most reactive -OH group
what is the result of an isomerisation reaction?
a compound with the same molecular formula but different structure
what does phosphoglucose isomerase do?
converts a pyranose (6-membered sugar) to a furanose (5-membered sugar)
what is the 2nd enzyme in glycolysis?
phosphoglucose isomerase
what is the 3rd enzyme in glycolysis?
phosphofructokinase
what does phosphofructokinase do?
adds a second phosphate group with the use of 1 ATP
what is the 4th enzyme in glycolysis?
aldolase
what does aldolase do in glycolysis?
splits the C6 compound into 2 C3 compounds
what is FBP
fructose-1,6-biphosphate
how is FBP bound to the enzyme aldolase?
as an imine, via schiff base reaction
Glyceraldehyde-3-phosphate Dehydrogenase is what number enzyme in glycolysis?
5th
which enzyme is the “trickiest” enzyme of glycolysis and why?
Glyceraldehyde-3-phosphate Dehydrogenase, because it adds a phosphate group without consuming ATP
Glyceraldehyde-3-phosphate Dehydrogenase generates energy in the form of what?
NADH/H+ (per intermediate of glucose, so 2)
what is the 7th enzyme of glycolysis?
phosphoglyceromutase?
what does a mutase enzyme do?
moves a functional group from one position to another on the same molecule
what two functional groups are switched by phosphoglyceromutase?
an -OH group and a phosphate group
what is the 8th enzyme of glycolysis?
Enolase
what kind of reaction does enolase catalyze?
a dehydration reaction
what is the 6th enzyme of glycolysis?
phosphoglycerate kinase
what does phosphoglycerate kinase do in glycolysis?
backwards kinase, removes a phosphate group, generates 2 ATP (1 per intermediate of glucose)
what is the 9th and last enzyme of glycolysis?
pyruvate kinase
what does pyruvate kinase doe?
acts as a backwards kinase, removes aphosphate generating 2 ATP
what does NAD stand for?
nicotineamide adenine dinucleotide
NADH/H+ can be reduced to what and where in the cell?
ATP, in the mitochondira
how many ATP are made from anaerobic metabolism of ATP?
36-38 ATP
how do the reduced co-factors of glycolysis, (suc as NADH/H+) reach the inner mitochondria?
shuttle systems
what is the name of the shuttle systems that allows the reduced co-factors of glycolysis, (suc as NADH/H+) reach the inner mitochondria?
glycerol-3-phosphate shuttle, and malate aspertate shuttle
which shuttle system for NADH/H+ yields more ATP?
glycerol-3-phosphate shuttle
