Unit 3

Know how carbon atoms are numbered in monosaccharides

Count the first one

What is the metabolic basis for the observation that many adults cannot ingest large quantities of milk without developing gastric difficulties?

Stop turning on the gene for making lactase which can digest milk

From which two monosaccharides is sucrose made? Lactose?

Sucrose- Fructose reacts with glucose Lactose- galactose joined to glucose by a β-1,4-glycosidic linkage

What is the source of our energy, and what is its fate in the body?

The energy used by all but a very few living things on earth, ultimately, comes from the sun. Plants convert sunlight to potential energy stored in the bonds of carbohydrates. Plant-eating animals use this energy for immediate use and store the excess in the bonds of fats. Other animals, including humans, eat plants and/or animals and use the chemical energy these organisms have stored.

Define "oxidation" and "reduction."

"oxidation", it is important to understand what that means. It refers to the loss of electrons, or addition of oxygen "reduction"can be gain of electrons, gain of hydrogen, or loss of oxygen Oxidation and reduction always occur together. Each increase in the number of carbon-oxygen bonds is an oxidation, and each increase in the number of carbon-hydrogen bonds is a reduction Electron carriers are the strategy that cells have for dealing with lost Electrons. Because the reduced coenzymes, NADH and FADH(2), have picked up electrons (in their bonds to hydrogen) that are passed along in subsequent reactions, they are often referred to as electron carriers.

What are the most common disaccharides found in nature and what purpose(s) do they serve?

-sucrose glycosides composed of 2 monosaccharide units -sig source of calories in human diet -eat this, mediated by enzymes synthesized by cells lining the small intestine

What suffix is in the name of most carbohydrates?

-OSE

In aqueous solution, monosaccharides are found in a cyclic conformation. Why is this True?

Aldehyde, acts the hydroxide which is far enough away which creates a cyclic structure. 20.3 slide 17

What is the definition of "metabolism?"

All the chemical reactions that take place in cells to break down or build molecules

Explain why cows can use cellulose as a source of energy, while humans can't.

Among mammals, only those that are ruminants (cudchewing animals like cows and horses) can process cellulose. This is because they have special bacteria and microorganisms in their digestive tracts that do it for them. They are then able to absorb the broken-down cellulose and use its sugar as a food source. Fungi are also able to break down cellulose into sugar that they can absorb, and they play a major role in the decomposition (rotting) of wood and other plant material. Humans do not have this bacteria to break down cellulose.

Amylose (a form of starch) and cellulose are both polymers of glucose. What is the main structural difference between them?

Amylose has α-1,4-glycosidic bonds, whereas cellulose has β(1→4) glycosidic bonds. Humans can digest amylose but not cellulose. • Glucose molecules in cellulose are found in an alternative pattern where one is down and one is up, but in amylose, glucose molecules are in the same orientation • Amylose is in starch, and they serve as the energy storage compound in plants. Cellulose is mainly a structural compound, which participates in cell wall formation, in plants.

How are amylose and amylopectin similar to each other, and how are they different from each other?

Amylose- accounts for about 20% of starch. It is somewhat soluble in hot water and consists of several hundred to a thousand D-glucose units linked in long chains. Amylose tends to coil into helices. Amylopectin- accounts for about 80% of starch. It has up to 100,000 glucose units per molecule and a-1,6 branches approximately every 25 units along its chain. It is not soluble. Because of hydrogen bonding, amylose acquires a spiral structure that contains six glucose units per turn. Amylopectin is a branched-chain polysaccharide composed of glucose units linked primarily by α-1,4-glycosidic bonds but with occasional α-1,6-glycosidic bonds, which are responsible for the branching.

List major functions of carbohydrates

Carbohydrates in food are important sources of energy. Carbohydrates are also found in cell walls and in the protective coatings of many organisms. Other carbohydrates are marker molecules that allow one type of cell to recognize and interact with another type. Good identify factors

What are the structures and functions of the following polysaccharides: cellulose, starch, and glycogen?

Cellulose- It makes up the cell walls in plant cells. These are much tougher than cell membranes. This toughness is due to the arrangement of glucose units in the polymer chain and the hydrogen-bonding between neighbouring chains. Starch- is often produced in plants as a way of storing energy. It exists in two forms: amylose and amylopectin Glycogen- Starch from plants is hydrolysed in the body to produce glucose. Glucose passes into the cell and is used in metabolism. Inside the cell, glucose can be polymerised to make glycogen which acts as a carbohydrate energy store.

What is the difference between digestion and metabolism?

Digestion refers to how the body processes food in the gastrointestinal (GI) tract and eliminates food waste via the intestines. Metabolism refers to how the cells utilize the energy we have absorbed from food during digestion

Most monosaccharides are chiral. What structural feature makes a molecule chiral?

Due to having so many carbons there is a high chance that one of them is chiral Chiral- 4 different

What is the root cause of dental caries (i.e.tooth decay)?

Due to whats left over after eating which doesn't go away, bacteria which inturn creates acid and if low enough can affect the root of the tooth 697

Stage 4- ATP Production

Electrons from the reduced coenzyme are passed from molecule to moleulce down an elcetron-transport chain. Their energy is harness to produced ATP At the end of the process, these electrons- along with hydrogen ions from the reduced coenzymes- combined with oxygen to produced water The reduced coenzyme are oxidized coenzyme are oxidized by atmospheric oxygen, and the energy that they carried is stored in the chemical bond of ATP molecule.

Oxidation of food molecules involves the loss of electrons. Where do the electrons go?

Enzyme cofactors (NAD and FADH)

What are the four stages of catabolism? Stage 1- Digestion

Enzymes in saliva, the stomach, and the small intestine convert large molecules to smaller molecules. Carbohydrates are brown down to glucose and other sugars Proteins are broken down to amino acids Lipids are broken down to glycerol and fatty acids These smaller molecules are transferred into the blood for transport to cells throughout the body.

What function does starch have in a plant? What function does cellulose have in a plant?

Function of starch in a plant= energy storage Function of cellulose in a plant= structure, such as steam, leaves, (cell wall)

How are monosaccharides connected to each other to form disaccharides, oligosaccharides, and polysaccharides?

Gliocyte bonds- alpha and the beta - Polysaccharides- amylose uses alpha- 1, 4 while cellulose uses Beta, 1-4 glycosidic bonds

What are the most abundant monosaccharides found in nature and what purpose(s) do they serve?

Glucose bc primary fuel for living cells -D fructose, fruit sugar, honey -- one of the 2 monosaccharides combined in the disaccharide sucrose

Amylopectin (a form of starch) and glycogen are both-linked polymers of glucose. What is the structural difference between them?

Glycogen has many more branches and contains up to one million glucose units per molecule.

What are the naming conventions for monosaccharides?

If the sugar has an aldehyde group, it is an aldose. If it has a ketone group, the sugar is classified as a ketose. A carbon must be double bonded to a oxygen

What are the two major types of metabolic pathways in living organisms?

Linear, Cyclic, and Spiral

How are the reactions that break down food molecules organized?

Metabolic pathways

Recall the definition of an enantiomer

Non superimposable pair of molecules that are mirror images of each other

Explain why cotton fibers, which are nearly pure cellulose, are insoluble in water, while glycogen, another polymer of glucose, will dissolve in water.

Our bodies do not have the enzymes required to digest cellulose, yet it is a necessary addition to a healthy diet. Why? This is because it forms a major part of the dietary fiber that we know is important for proper digestion. Since we cannot break cellulose down and it passes through our systems basically unchanged, it acts as what we call bulk or roughage that helps the movements of our intestines.

What is the origin of the term carbohydrate? Which elements are found in carbohydrates?

Polyhydroxie ketone or aldehyde- best def

Stage 2- Acetyl-Coenzyme (A production)

The small molecules from digestoin follow pathways that move their carbon atoms into two- carbon acetyl groups The acetyl groups are attached to coenzyme A to form "acetyl CoA" Acetyl-CoA in an intermediate in the metabolism of all food molecules.

What makes a monosaccharide an aldose? ketose? triose? Aldotetrose? Etc.

The sugar is an aldose if it contains an aldehyde functional group. A ketose signifies that the sugar contains a ketone functional group

Why are monosaccharides called simple sugars?

They are called monosaccharides due to being made up of simple sugars and the building blocks for larger carbohydrates

Which optical isomer of monosaccharides predominates in nature, D- or L- isomer? Why is this important?

We favor D. Enzyme monosaccharides that are used prefer d

Stage 3- Citric Acid Cycle

Within mitochondria, the acetyl-group carbon atoms are oxidized to the carbon diozide that we exhale Most of the energy release in the oxidation leaves the cirtic acid cycle in the chemical bonds of reduced coenzymes (NADH, FADH(2)) Some energy leaves the cycle stores in the chemical bonds of adenosine triphoshate (ATP) or related triphosphate.

Why are the two components of plant starch?

amylose and amylopectin

What function does glycogen have in mammals?

stores energy in animals in the liver and muscles