Bio1 10/5 Lecture: Carbohydrate Structure + Pre-Class Videos

What is a skeletal structure? How do you read one?

A skeletal structure is a simplified representation of a carbon-containing molecule.

• Every solid line is a covalent bond.

• Carbon atoms are not explicitly shown. Every intersection and end of a line is a carbon atom.

• Hydrogen atoms bonded to carbon atoms are not explicitly shown. It is implied that every carbon atom is bonded to enough hydrogen atoms to fulfill an octet.

• Atoms that are not carbons or hydrogens bonded to carbons must be explicitly shown.

What is glucose?

A hexose, which are 6-carbon sugars.

What are the two forms of a glucose molecule? Which is more common (and draw that form)?

A non-cyclic form and a cyclic (ring) form.

The cyclic form is much more common.

• The bottom three lines are drawn thicker to show that the bonds are pointing forward.

Number the carbons in a glucose molecule.

The only carbon outside the ring is carbon-6. This identifier wouldn’t work for sugars that have two carbons outside the ring (such as fructose).

What are the major types of macromolecules? Which one is the only macromolecule that is not a polymer?

Proteins, nucleic acids, carbohydrates (polysaccharides), and lipids.

Lipids are not polymers.

What are polymers and monomers?

A polymer is a macromolecule made up of many repeating subunits.

Those subunits are monomers, which are usually small molecules like sugars and amino acids.

What are nucleic acids monomers?

Nucleotides

What are the two main types of nucleic acid polymers?

DNA and RNA

What is the difference between nucleotides and nucleosides?

Nucleosides do not have any phosphate groups.

What is a free-floating DNA or RNA nucleotide made of? How is it different from a nucleotide that is bonded to form DNA or RNA?

A pentose (5-carbon sugar), a nitrogenous base, and three phosphate groups

A bonded nucleotide in DNA or RNA only has one phosphate group. Two are lost when linking together to form DNA or RNA.

What sugar is found in DNA versus RNA? How can you identify them structurally?

DNA contains deoxyribose, while RNA contains ribose.

Ribose has an oxygen atom at the carbon-2, while deoxyribose does not.

What is a nitrogenous base? How can you differentiate them from sugars?

What are the five primary nitrogenous bases found in DNA and RNA?

A cyclic structure that contains nitrogen. You can easily differentiate them from sugars because they have nitrogen instead of oxygen atoms inside the ring.

The five primary nitrogenous bases found in DNA and RNA are adenine, thymine, guanine, cytosine, and uracil.

Ribosomes: what do they make and what are they made of?

They are made of protein and ribosomal RNA. They make proteins.

What is the ribosomal RNA gene? How is it useful for identifying bacteria species?

It is the DNA sequence that codes for ribosomal RNA.

All bacterial species have a unique rRNA gene called the 16S, which can be used to identify the species of a bacteria.

What is PCR?

Polymerase Chain Reaction, or PCR amplification (used interchangeably)

It is a lab technique used to make many copies of a specific DNA sequence.

What are the mitochondria? List the basic structures and functions.

Why is it unique from other organelles?

It is an organelle that generates ATP through cellular respiration, which is converted into energy.

Unlike most organelles, it has ribosomes and DNA and can duplicate itself.

It has two layers, an outer membrane and an inner membrane, an intermembrane space, and the matrix.

Describe the three steps of cellular respiration.

1. Glycolysis occurs outside the mitochondria. It breaks glucose into two pyruvates, producing 2 ATP.

2. The pyruvates are moved into the matrix of the mitochondria and are used to power the Krebs cycle. The Krebs cycle creates NADH and FADH₂ and 2 ATP, as well as CO₂ as a byproduct.

3. The electron transport chain uses the NADH and FADH₂ to power protein pumps in the inner membrane, in order to make about 34 ATP. It produces depleted NADH and FADH₂. It also combines oxygen with its waste products to create H₂O as a byproduct.

How should the slope of a diagram representing a reversible reaction be drawn?

The diagram should not be drawn with a lag at the beginning.

It should be drawn so that the rate of the reaction is greatest at the start.

How are monomers combined to form polymers?

Condensation reactions, or dehydration synthesis, form covalent bonds between monomers. Each covalent bond formed releases a small molecule, usually water.

How are polymers broken into monomers?

Hydrolysis reactions break covalent bonds in polymers. Each covalent bond broken requires a small molecule, usually water.

What are the monomers and polymers of carbohydrates called?

The monomers are called monosaccharides.

The polymers are called polysaccharides.

What are the three main functions of carbohydrates?

• They store energy in living organisms.

• They are structural components in cells, especially plants (e.g. cellulose).

• They often bind to other macromolecules, like proteins and lipids, to alter their shapes and functions.

What are the bonds that link monosaccharides called? What is the specific one that links glucose molecules?

Glycosidic bonds/linkages.

A 1,4 glycosidic bond/linkage connects the carbon-1 and carbon-4 between glucose molecules.

What are hydroxyl groups? What do they do?

A common function group contained in carbohydrates and many other biological molecules.

They are alcohols (e.g. ethanol).

They are polar and allow for hydrogen bonding, meaning they can make molecules water-soluble. They also enable condensation/dehydration synthesis.

What are three examples of glucose polymers?

Cellulose, starch, and glycogen

Describe the function and structure of cellulose.

What and how many glycosidic bonds can it form?

It is a important structural molecule, especially in plants. It forms linear strands.

It can form two 1,4 glycosidic bonds.

Describe the function and structure of starch.

What and how many glycosidic bonds can it form?

It is made by plants to store energy and used by animals to obtain energy. It forms branches.

It can form more than two glycosidic bonds. It forms both 1,4 and 1,6 glycosidic bonds.

Describe the function and structure of glycogen.

What and how many glycosidic bonds can it form?

It is a major energy storage molecule in mammals. It forms a lot of branches.

It can form more than two glycosidic bonds. It forms both 1,4 and 1,6 glycosidic bonds.