Lecture 2: Glucose transport, glucose and glycogen

Question 1

what is the Gibbs free energy value for ATP

Answer 1

-7.3

Question 2

true or false: all derivatives of ATP and ADP and ADMp have negative free energy values

Answer 2

True

Question 3

is glucose tranported into the cell through energy in most cells

Answer 3

no , down a concentration gradient by facilitated diffusion

Question 4

is a protein carried needed for glucose transport? is the energy needed?

Answer 4

protein yes

energy no

Question 5

what are the 2 most commonly studied glucose carriers and do they require insulin

Answer 5

glut (no insulin) and glut 4 (insulin dependent)

Question 6

true or false: most post absorptive glucose uptake by cells does not require insulin

Answer 6

true

Question 7

where is the glut 4 (insulin dependant) located

Answer 7

skeletal muscles, adipose and heart tissue)

Question 8

do all glut receptors/carriers require insulin

Answer 8

no

Question 9

are all glucose transporters membrane-bound?

Answer 9

no , glut 4 is in vessicles in the skeletal, adipose amd heart tissue

Question 10

which glut receptors are membrane bound

Answer 10

glut 1
glut 2
glut 3

Question 11

which receptor is in vesicles

Answer 11

glut 4

Question 12

Where is glut 1 receptors located

Answer 12

most tissues (brain, RBS, placenta)

Question 13

where are glut 2 receptors located

Answer 13

liver, kidneys, intestine, pancreatic b cells

Question 14

where are glut 3 receptors located

Answer 14

low levels in most tissues but high expression in neurons

Question 15

where are glut 4 transporters located

Answer 15

msucle, adipose and heart

Question 16

affinity defintion

Answer 16

degree of attraction that glucose has to tranposter

Question 17

km defintion and why

Answer 17

concentration of glucose at which uptake velocity is half maximal

this is the point the transporter is most active phase

Question 18

features of Glut 1

Answer 18

LOW KM (1 mM)
HIGH AFFINITY (NEAR CONSTANT UPTAKE) = glucose binds very easily to transporter

Question 19

what glucose transporter has a near constant uptake

Answer 19

glut 1

Question 20

features of glut 2

Answer 20

High Km (15-20 mM)
respond only to high glucose concnetration

Question 21

when is glut 2 very active

Answer 21

POST PRANDIAL BLOOD LEVELS

Question 22

explain glut 1:

Answer 22

high concentration in the brain cells and rbc
They are constantly taking up glucose therefore there is a strong attraction and you do not need a high concentration of it to activate the transporter

Question 23

explain glut 2 transporter

Answer 23

After eating, there is a high concentration of glucose in the cell.
The liver will take excess carbs of glucose and store it as glycogen to lower the glucose blood level
RESPONDS FAVORABLY TO HIGH CONCENTRATIONS OF GLUCOSE
will not activate at low levels of glucose or it will cause you to uptake too much glucose

Question 24

which transporter responds favourably to high concentrations of glucose

Answer 24

glut 2

Question 25

what is typical blood glucose concentration

Answer 25

4-8 MM

Question 26

features of glut 3

Answer 26

``` low Km (less than 1), high affinity allows for preferential uptake of glucose during hypoglycemia ```

Question 27

which transporter allows preferential uptake of glucose during hypoglycemia

Answer 27

glut 3

Question 28

glut 4 features

Answer 28

medium km (2.5-5), insulin dependancy in recruitment of glut 4 from intracellular stores

Question 29

true or false: all gluts are ACTIVE MEDIATED transporters | ie. transport glucose up concentration gradient only

Answer 29

false PASSIVE down concentration gradient

Question 30

STUDY THE GRAPH OF GLUCOSE TRANSPORTERS AND KM

Answer 30

.

Question 31

ranks these in increasing order of KM | glut 1,2,3,4

Answer 31

glute 1 glute 3 glute 4 g;ute 2

Question 32

Tissues with low km and high affinity use which 2 glut transporters

Answer 32

glut 1 and glut 3

Question 33

what is the function of tissues with low km and high affinity

Answer 33

protect from any negative affects of hypoglycemia (ex: syncope)

Question 34

true or false: RBC have no mitochondria which is why they need near constant uptake of ATP

Answer 34

true

Question 35

true or false and explain: RBC and neuron are not only fueled by glycolysis

Answer 35

false, RBC metabolism is solely on glyoclysis so there needs to be an intake of glucose in the cell (dont need alot of energy and responds to low concerntration)

Question 36

explain how RBCs and Neurons protect themselves from hypoglycemia

Answer 36

SInce they have such a high afinity and low km, they do not need a lot of glucose to function correctly Even during periods of low concentration (2.5 MM of glucose, they will still take up atp)

Question 37

which glut transporter works best for periods of transcietn HYPERGLYCEMIA/post prandial

Answer 37

glut 2

Question 38

which glut transporter works better in periods of hyperglycemia

Answer 38

glute 2

Question 39

which glute receptor works best for periods of normal blood sugar

Answer 39

glute 4

Question 40

which glut receptors work best with hypoglycemic conditions

Answer 40

glute 1 and glute 3

Question 41

explain why tissues with high km and low affinity are good for hyperglycemia

Answer 41

Glut 2 (in liver, b cells) have an extremely high rate of transport but only at high concentrations of blood glucose therefore it will take up a lot of glucose as glycogen and secreting insulin to allow glycogen storage in muscles

Question 42

what are the two pathways for glucose/sucrose etc

Answer 42

can be stored as glycogen | go to glycolysis

Question 43

true or false: the skeletal muscles can only take up glucose?

Answer 43

false, it can take up glucose, fructose and galactose

Question 44

fructose, galactose and glucose all need ATP

Answer 44

true

Question 45

When ATP is broken down with galactose, what does galactose become

Answer 45

galactose 1 phosphate

Question 46

when atp is broken down, what does the glucose become

Answer 46

glucose 6 phosphate

Question 47

when atp is broken down, what does frcutose become

Answer 47

fructose 6 phsophate

Question 48

true or false, all sugars need to go through phosphorylation for reactions within the cell

Answer 48

true

Question 49

what is fructose made from

Answer 49

sucrose and glucose

Question 50

what is galactose made from

Answer 50

glucose and lactose

Question 51

what is the enzyme that converts galactose to galactose 1 phosphate

Answer 51

galactokinase

Question 52

what is the enzyme that converts glucose to glucose 6 phosphate

Answer 52

glucokinase (liver) | hexokinase

Question 53

what is the enzyme that converts fructose to fructose 6 phosphate or fructose 1 phosphate

Answer 53

fructokinanse (1) | hexokinase (6)

Question 54

is glucokinase found anywhere in the body?

Answer 54

no , only found in the liver

Question 55

is hexokinase found in the liver?

Answer 55

no

Question 56

true or false: hexokinase can be used only for glucose

Answer 56

false, can also be used for fructose

Question 57

true or false: glucose 6 phosphatase enzyme is only found in the liver

Answer 57

true

Question 58

function of glucose 6 phosphatase

Answer 58

Allows stores carbohydrates in the liver to be reprocessed into glucose (phosphate from glucose 6 phosphate binds to the enzyme) and allows glucose to leave the liver cells and enter the blood circulation convert monosacharrides (fructose and galactose) to glucose for export

Question 59

What is the only way we can constantly maintain blood circulation levels of blood glucose

Answer 59

through glucose 6 phosphate being reprocessed to glucose by the enzyme and exiting the liver

Question 60

is the process of glycogenesis reversible and if so what is it called

Answer 60

yes and glycogenolysis

Question 61

what is glycogenesis

Answer 61

new formation of glycogen in tissues to be stored

Question 62

explain glycogenesis in the liver

Answer 62

After eating, liver is going to take high levels of glucose. It enters the cell and gets converted to glucose 6 phosphate by GLUCOKINASE=spontanously Once converted to glucose 6 phosphate it can go up the pathway to become glycolysis, down the pathway to be glycolosis or it can go back out into the blood by phosphotase (glucose6phosphostase)

Question 63

what is glycogenolysis

Answer 63

breakdown of glycogen for energy when needed | done by glucose 6 phosphotase

Question 64

what is the last step needed to store the glucose as glycogen

Answer 64

need UTP instead of ATP

Question 65

Explain glucose into glycogen

Answer 65

1) glucose into glucose6 phosphate by hexokinase everywhere in the body and glucokinase in the liver(ATP drives reaction) 2) Glucose 6 phosphate to glucose 1 phophshate 3) Glucose 1 phoshphate into UDP glucose (UTP drives reaction) UTP is broken down, UDP binds to the glucose 4) UDP-glucose is stored AS GLYCOGEN by glycogen syntahse

Question 66

what is UTP

Answer 66

high energy compound (purine with ribose and 3 phosphates)

Question 67

what is the enzyme responsible for accelerating UDP glucose into glycogen

Answer 67

GLYCOGEN SYNTHASE

Question 68

do all glut receptors/carriers require insulin

Answer 68

no

Question 69

what hormone is going to stimulate glycogen synthase and why

Answer 69

insulin | and increased insulin stimulates uptake og glucose into the cell that will be stored as glyocgen

Question 70

what is glycogenin

Answer 70

protein that acts as an achor that allows glucose to bind and start to form the glycogen tree