Week 3 Day 2 Biochemistry

Question 1

Lactose is cleaved into glucose and galactose by which enzyme?

Answer 1

lactase

Question 2

In going from pyruvate to acetyl CoA, how many molecules of CO₂ are generated from 2 pyruvate?

Answer 2

2 CO₂

Question 3

Though we produce some ATP from glycolysis, and some ATP from the kreb’s cycle, where do we ultimately produce the most ATP and how?

Answer 3

The electron transport chain through oxidative phosphorylation

Reduced intermediates, NADH and FADH₂, produced from glycolysis, pyruvate oxidation, and the kreb’s cycle, go into the ETC to produce ATP

Question 4

Is glycolysis an aeorbic or anaerobic process?

Answer 4

Glycolysis is anaerobic. It does not consume any O₂ or produce any CO₂.

Question 5

Sucrose is made of which two sugars?

Answer 5

Glucose + Fructose

Question 6

Between omega 3 and omega 6 fatty acids, which ones will be more fluid in our cell membranes?

Answer 6

Omega 3 fatty acids because the melting point is lower.

Question 7

How many ATP’s are produced in the Kreb’s cycle?

Answer 7

2

Question 8

Besides glycolysis, name 3 other fates of glucose.

Answer 8

1. Glucose can be stored as glycogen

2. Glucose can be broken down in to a 3 carbon glycerol to aid in making plasma membranes and storing fat

3. We can pull a carbon off of the glucose to make a pentose. This is the path in which we can synthesize pyrimidines and purines as well make DNA and RNA.

Question 9

Common name for omega 6 fatty acid

Answer 9

linoleic acid

Question 10

T or F: D-Ribose is an aldohexose.

Answer 10

False;

D-Ribose is an aldopentose

Question 11

T or F: In general, saturated fats are solid at room temperature.

Answer 11

True

*Think of bacon grease after cooking, lard*

Question 12

Is D-Fructose an aldehyde or a ketone?

Answer 12

A ketone, known as a ketohexose

Question 13

During one turn of the kreb’s cycle, how many CO2s do we lose or kick off?

Answer 13

2

**Remember, this is for ONE turn of the kreb’s cycle, from ONE Acetyl CoA from ONE pyruvate. We generate TWO molecules of pyruvate for every ONE glucose.**

Question 14

T or F: Fatty acids having one or more C-C double bonds are termed unsaturated.

Answer 14

True

Question 15

List the products of glycolysis.

Answer 15

For each glucose (6 carbon molecule)

we produce:

Two 3 carbon molecules of pyruvate

2 ATP

2 NADH

Question 16

Which molecule can we use to restore an oxaloacetate from the citric acid cycle?

Answer 16

pyruvate

Question 17

What is the purpose of an enzyme?

Answer 17

to speed up reactions

(S) - substrate

(E) - enzyme

(P) - product

S+E → ES → EP → E+P

Question 18

In the prcosess of glycolysis, glucose (a 6 carbon molecule) splits into two 3 carbon molecules. This can result in 2 pyruvates or 2 ________, which will be very important in making plasma membranes and storing fats.

Answer 18

glycerol - 3 - p

Question 19

In regards to fatty acids, fatty acids with longer carbon chains will have a higher or lower melting point?

Answer 19

higher

Question 20

Common name for omega 3 fatty acid

Answer 20

a-linolenic acid

Question 21

Do trans double bonds cause kinks?

Answer 21

No

*think of fake butter, trans fatty acids/trans fats”

Question 22

For every ONE glucose molecule, we kick off ___ CO₂s from pyruvate to Acetyl CoA, and ___ CO₂s during the kreb’s cycle?

Answer 22

2; 4

Question 23

What is an enzyme?

Answer 23

A catalyst made of protein

Question 24

T or F: Even though D-Fructose is a ketone, and D-Glucose, D-Mannose, and D-Galactose are aldehydes, all are hexoses.

Answer 24

True;

All 4 molecules are hexoses.

Question 25

T of F: Enzymes have the ability to change the energetics of a reaction.

Answer 25

False; Enzymes *do not* _add_ any energy and *do not* _take energy out_ of the reaction.

Question 26

What is the Respiratory Exchange Quotient (REQ) for glucose and palmitate?

Answer 26

CO₂ produced/exhaled : O₂ inhaled Glucose: 6/6 = 1.0 Palmitate 16/23 = 0.7

Question 27

Lactose is made of which two sugars?

Answer 27

Glucose + Galactose

Question 28

Besides D-Glucose, name 2 additional important aldehydes in our diet.

Answer 28

D-Galactose D-Mannose \*There are 16 total aldehydes of this kind, 8 D and 8 L. We are only discussing D-Glucose, D-Galactose, and D-Mannose\*

Question 29

Are enzymes regulated?

Answer 29

Yes, enzymes are regulated. They "turn on" or "turn off" based off of what our body needs.

Question 30

If a fatty acid has **no** C-C double bonds, is it *saturated* or *unsaturated?*

Answer 30

saturated

Question 31

Can fatty acids enter directly into the TCA cycle?

Answer 31

**Not directly, no**. A fatty acid chain can be broken down into 2 carbons a time → these can be added to a Coenzyme A to make an acetyl CoA → which can *then* enter the Kreb's cycle.

Question 32

Is D-Glucose an aldehyde or a ketone?

Answer 32

An _aldehyde_, known as an aldohexose

Question 33

Explain how omega 3 and omega 6 FA are named as such.

Answer 33

The carbon chains of the fatty acids are named with the carboxylic carbon as **#1**. If you count backwards from the end of the chain (omega), the first cis double bond will be either _3rd_ (omega 3) or _6th_ (omega 6) from the *omega* of the chain.

Question 34

Does this molecule represent an *aldohexose* or *ketohexose*?

Answer 34

an aldohexose

Question 35

How many carbons does D-Ribose have?

Answer 35

5 carbons

Question 36

T or F: Enzymes catalyze reactions in only _one_ direction.

Answer 36

False; Enzymes catalyze a reaction in _both_ directions.

Question 37

For primarily naming sugars and amino acids, we will use ___ and ___ to describe "right" and "left."

Answer 37

D and L D (dexter) - right L (laevos) - left

Question 38

Where in the cell does the TCA cycle occur?

Answer 38

the mitochondria

Question 39

D-Glucose is ____ handed structure.

Answer 39

right the D is for dexter or "right"

Question 40

What is an active binding site?

Answer 40

The place where a substrate (S) will bind to the enzyme, and where all of the enzymatic activity occurs.

Question 41

What molecule do we end up with when we _reduce_ NAD⁺?

Answer 41

we _gain_ a hydrogen, so **NADH** Remember OIL RIG acronym **O**xidation **i**s **l**oss (of electrons), **r**eduction **i**s **g**ain (of electrons)

Question 42

In which part of the mitochondria does the TCA cycle occur?

Answer 42

mitochondiral matrix

Question 43

Where does glycolysis occur in the cell?

Answer 43

cytoplasm

Question 44

Would you suspect a lower pH in the *inner membrane space* **or** the *matrix* of the mitochrondria?

Answer 44

**Inner membrane space** H⁺ is pumped out of the matrix into the inner membrane space, contributing to membrane potential.

Question 45

Why would we ever need to restore an oxaloacetate from pyruvate?

Answer 45

Whenever we take something out of the cycle, we have basically reduced our oxaloacetate and lost a net oxaloacetate. i.e. Succinyl CoA → porphyrins → heme a-Ketoglutarate → glutamate → purines

Question 46

Does this molecule represent an *aldohexose* or *ketohexose*?

Answer 46

A ketohexose

Question 47

Where is fructose primarily processed?

Answer 47

The liver

Question 48

Sucrsose can be cleaved into glucose and fructose by which enzyme?

Answer 48

sucrase

Question 49

What does the liver like to do with fructose?

Answer 49

The liver likes to make glycerol out of fructose.

Question 50

During pyruvate oxidation, 1 carbon is cleaved from _pyruvate_ (3 carbon molecule) to form _Acetyl CoA_ (2 carbon compund). What happens to the cleaved carbon?

Answer 50

This becomes a CO2.

Question 51

Glycerol is the "backbone" for which type of molecule?

Answer 51

A triglyceride. A triglyceride has a glycerol backbone with 3 fatty acids

Question 52

In the citric acid cycle, we add Acetyl CoA (2 carbons) to \_\_\_\_\_\_\_\_\_\_(4 carbons) to form Citrate/Citric Acid (6 carbons).

Answer 52

Oxaloacetate

Question 53

T or F: Under *aerobic* conditions, the _pyruvate_ produced from glycolysis is converted to lactic acid.

Answer 53

False; Under **aerobic** conditions, each pyruvate is converted into Acetyl CoA to feed into the Kreb's cycle. Pyruvate is reduced to lactate under **anerobic** conditions.

Question 54

How do enymes catalyze a reaction?

Answer 54

By lowering the transition energy of the reaction, making the reaction go much faster.

Question 55

Adding double bonds to a fatty acid greatly _________ the melting point.

Answer 55

**reduces** The more _cis_ double bonds, the more kinks in the fatty acids, the less tightly the FA chains can be packed together.

Question 56

When glucose enters the cell for glycolysis, it is immediately phosphorylated to make \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_.

Answer 56

glucose 6 phosphate

Question 57

In the Michaelis Mentin equation, what is K_m?

Answer 57

K_m is the substrate concentration at which the reaction rate is at half maximum K_m = V_Max/2

Question 58

In the Michaelis Mentin equation, what is Vmax?

Answer 58

V_max is the maxmimal velocity (rate) a reaction can achieve at an infinite concentration of substrate. \*The enzyme is completely saturated with substrate\*

Question 59

Is the Kreb's cycle anabolic, catabolic, or amphibolic?

Answer 59

Amphibolic

Question 60

Michaelis Menten equation

Answer 60

V = Vmax \* S / Km + S