Cell Structure &functions Lec 8

Question 1

Define Carbohydrates

Answer 1

Anything that ends in “os” Glucose/fructose and are not entirely distinct
-Has sugar molecules and are polymerized into a complex
-Sugars are a part of lipids and nucleotides, including (ATP and GTP)

Question 2

What is the cellular roles of carbohydrates?

Answer 2

-Play a critical role in cells
-Structural support
-Protection from damage
-A significant source of cellular energy

Question 3

Define Glycogen

Answer 3

-Stores excess glucose
-Is a polymerized chain of glucose molecules
*Sugars cannot cross membranes without transport
*Cells have transport for specific sugars
*Glucose and other sugars are uncharged polar molecules

Question 4

What do sugars and carbohydrates do, and are carbs high or low in transport?

Answer 4

1)Sugars contribute to every class of macromolecule (DNA, RNA, Lipids, proteins)
2)Carbohydrates can be taken up from the environment or used in intercellular stores
3)The transport, storage, and use of carbohydrates is highly regulated

Question 5

Metabolic pathway

Answer 5

-A series of coupled enzymes catalyzed chemical reactions that convert one major macromolecule to another
-The product of one enzyme-catalyzed reaction becomes the substrate for the next enzyme-catalyzed reaction

Question 6

Metabolite

Answer 6

-Are known to be intermediate macromolecules
-Are both substrates and products

Question 7

Single Reaction

Answer 7

-The substrates are consumed, and the products are produced
Metabolite 1-Metobolite 2=product

Question 8

Linear pathway

Answer 8

-Intermediate steps are ignored due to the production and consumption of metabolites canceling each other out

Question 9

Net reaction

Answer 9

-When only the initial substrates and any molecules that enter the pathways are considered consumed
-Only the final product and any molecules that exit the pathway are considered produced

Question 10

Anabolism

Answer 10

-A metabolic pathway
-Anabolic pathways create more complex macromolecules
-Required energy is ATP hydrolysis

Question 11

Define Catabolism

Answer 11

-A metabolic pathway
-Catabolic pathways break down complex macromolecules
-Generate raw materials
-Provide energy
-Catabolic pathways lead to ATP production

Question 12

What is a metabolism, catabolic breakdown, and anabolic pathway

Answer 12

-Metabolism depends on a series of enzymes catalyzing coupled reactions
-Catabolic breakdown leads to the production of raw materials and energy
-Anabolic pathways build essential macromolecules but require energy

Question 13

Define Glycosis

Answer 13

-Occurs in the cytosol cells
-First step is phosphorylating glucose
-Converts on glucose (6C) into two pyruvate(3C)
-Produces two net ATP (hydrolyzes 2, produces 4)

Question 14

What is the number of ATP produced by glycolysis

Answer 14

Two consumed
Breaks down
4-2=2ATP

Question 15

what are the effect of glucose phosphorylation on transport?

Answer 15

Phosphorylation keeps glucose in cells

Question 16

What are the multiple entry points into a pathway (glucose vs. glucose-6P)

Answer 16

1)Dietary Glucose
2)Blood Glucose
3)Tissue Glucose 6p
-After eating, GLUTI transports glucose from the bloodstream into cells

Question 17

What is the irreversible reactions that gives a pathway direction?

Answer 17

∆G is so negative that the reverse reaction won’t occur.

Question 18

Define Gluconeogenesis

Answer 18

-Instead of breaking glucose down into two, glucogenesis takes two pyruvates and glues them together to make a glucose level.
-When glucose levels are low, parts of the glycolytic pathway can run in reverse to male glucose from two pyruvates

Question 19

What is the Regulation of phosphofructokinase (ATP inhibition vs. ADP activation)
ATP

Answer 19

-ATP binds to the active site of phosphofructokinase as a substrate
-ATP can also bind to an allosteric site in phosphofructokinase to inhibit its catalytic activity
-High ATP levels inhibit phosphofructokinase activity stalling glycolysis
-High ATP levels inhibit phosphofructokinase activity increasing fructose-6P levels
-Phosphoglucose isomerase can easily carry out the reverse reaction to produce glucose-6P
-Glucose-6P is a feedback inhibitor of hexokinase activity

Question 20

What is the Regulation of phosphofructokinase of ADP activation

Answer 20

ADP
-ADP can also bind to an allosteric site on phosphofructokinase
-High ADP levels activate phosphofructokinase to increase glycolysis

Question 21

What are Glycotic enzymes, and what are their roles?

Answer 21

Glycolytic enzymes respond to high ATP levels by inhibiting glycolysis to reduce ATP production.

-Glycolytic enzymes respond to high ADP levels by activating glycolysis to increase ATP production

Question 22

What happens when an enzyme is inhibited?

Answer 22

-Inhibiting an enzyme in the middle of a pathway can lead to the buildup of metabolites that inhibit an
enzyme at the beginning of the pathway

Question 23

What is an Indirect inhibition (hexokinase example)

Answer 23

A glucose-6P feedback inhibitor of hexokinase activity