Exam 1

Briefly explain the job of DNA in producing proteins.

The sequence of nucleotide bases in a DNA strand contains information about how to produce a particular protein.

define organic molecule

a molecule that contains carbon

Only specific substrates can fit in an enzyme's _________ to catalyze a reaction.

active site

building block of proteins

amino acids

The four major types of macromolecules that are necessary for our cells:

carbohydrates, proteins, nucleic acids, lipids

carbohydrates contain...

carbon, hydrogen, and oxygen in a 1:2:1 ratio

List two important examples of sterols:

cholesterol, and steroid hormones (estrogen, testosterone)

Proteins are similar to carbohydrates and lipids because they too contain carbon, oxygen, and hydrogen; however, proteins can be distinguished from these other important macromolecules because they also contain...

nitrogen

The building blocks of nucleic acids are

nucleotides

building block of nucleic acids

nucleotides

Cells will build protein by linking amino acids together by a...

peptide bond

The possible shapes, or structure, of proteins are:

primary, secondary, tertiary, quaternary

primary function of carbohydrates

provide fuel for the cell

Monosaccharides aka...

simple sugars

A nucleotide is made up of three parts:

1. A phosphate group (PO4) 2. a sugar 3. a nitrogen containing base

Explain why we call the clear or opaque protein of an egg, an egg "white."

We call the clear or opaque protein of an egg, an egg "white" because it turns white after the process of denaturation. The extreme heat the egg experiences while being cooked breaks the hydrogen bonds that give the proteins their natural shape. The proteins in the clear egg white unfold, losing their secondary and tertiary structure.

Identify the three main groups that make up an amino acid

carboxyl group, amino group, side chain (R group)

When a protein is exposed to an extreme environment, such high temperature or changes in pH, what is the term that is used to describe what has occurred?

denaturation

Two types of nucleic acids:

deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)

define macromolecule

A large molecule, made up of smaller building blocks of subunits

Define hydrophilic

Attracted to water, as, for example, polar molecules that readily form hydrogen bonds with water. "water loving"

What is the function of glycogen in humans?

Glycogen is the primary energy storage in humans.

Like other macromolecules, the structure of lipids includes the elements C, O, and H, but lipids have a higher ratio of C−H bonds. How does this affect lipids?

Lipid have more C-H bonds than carbohydrates. This gives lipids the capacity to store more energy than carbohydrates can

what is the function of starch in plants?

Starch is the primary energy storage in plants.

Define metabolism, including the role of enzymes.

enzymes' catalytic capacities give the chemical "nudge" needed to get reactions to happen at a rate that can sustain life. Taken together, all of the chemical reactions in a living organism are its metabolism

What is the basic structure of all sterols?

four interlinked rings of carbon atoms

Draw the basic structure of a phospholipid:

hydrophilic head, hydrophobic tail

Define polysaccharide

many monosaccharides (even thousands) linked together

The fats that we are concerned about in the food we eat are called:

triglycerides

Define disaccharide

two monosaccharides linked together

What is chitin and where is it found?

complex carbohydrate that is indigestible by humans. Forms the rigid outer skeleton of most insects and crustaceans (such as lobsters and crabs).

What makes one amino acid different from another?

the side group which determines the property of the amino acid

List three types of lipids and their functions:

1. FAT: most important in long-term energy storage and insulation. (Penguins and walruses can maintain relatively high body temperatures, despite living in very cold habitats, due to their thick layer of insulating fat.) 2. STEROLS: Regulates growth and development. include cholesterol and many of the sex hormones 3. PHOSPHOLIPIDS: form the membranes that enclose cells.

There are three major differences between DNA and RNA. List the ways RNA is unique:

1. the sugar portion of the nucleotide contains an extra atom of oxygen. 2. RNA has Uracil instead of Thymine 3. RNA is single stranded

Each nucleotide (in DNA) can contain one of _____ different bases. These bases include:

4. Adenine, Guanine, Thymine, Cytocine

Which DNA bases pair together?

Adenine & Thymine. Guanine & Cytosine

Chemical formula for glucose

C6H12O6

What is your favorite food that's high in unsaturated fats?

I like to cook with olive oil

Briefly explain the job of RNA in producing proteins.

RNA acts as a middleman molecule—taking the instructions for protein production from DNA to another part of the cell, where, in accordance with the RNA instructions, amino acids are linked together into proteins.

What is your favorite food that's high in saturated fats?

cheese

Our cells require amino acids for various cellular structures and activities. Cells can make some of the amino acids that are required, but not all of them. Other necessary amino acids are obtained through the diet. The amino acids we must be certain to include in our diet are called...

essential amino acids

Examples of simple sugars:

glucose, fructose, galactose

phospholipids play an important role in the cell's

membrane

building block of carbohydrates

monosaccharides

It is often easier to draw DNA as if it were a ladder. The vertical uprights of the ladder would be made out of __________. The rungs of the ladder, or where you would place your foot if you were climbing the ladder, would be the ______________.

sugar-phosphate backbones, nucleotide base pairs

There are then several potential end results for the glucose circulating in the blood. Explain the three potential fates:

1. If energy is needed, glucose can be used as fuel for cellular activity. once it arrives at and enters a cell, glucose can be used as an energy source. 2. Stored temporarily as glycogen. If glucose is circulating in your bloodstream in excess of your body's needs, it can be temporarily stored in various tissues, primarily in muscles and liver. The stored glucose molecules link together to form a large web of molecules called glycogen. When you need energy later, glycogen can be easily broken down to release glucose back into your bloodstream. 3. glucose in your bloodstream can be converted into to fat - a form of longterm energy storage.

The rate at which an enzyme catalyzes a reaction is influenced by several chemical and physical factor. These include:

1. P.H. enzymes have an optimum pH. Above or below this pH, excess hydrogen or hydroxide ions interact with amino acid side chains in the active site or elsewhere. These interactions disrupt enzyme function (and sometimes structure) and decrease reaction rates. 2. TEMPERATURE. Because molecules move faster as temperature increases, reaction rates generally increase similarly. Reaction rates continue to increase only up to the optimum temperature for an enzyme. At temperatures above the optimum, reaction rates decrease as enzymes lose their shape. Enzymes from different species can have widely differing optimum temperatures. 3. ENZYME AND SUBSTRATE CONCENTRATION. The rate of a reaction typically increases with the addition of either more enzyme or more substrate 4. PRESENCE OF INHIBITORS AND ACTIVATORS. One of the most common ways that cells can speed up or slow down their metabolic pathways is through the binding of other chemicals to enzymes. This binding can alter enzyme shape in a way that increases or decreases the enzyme's activity

Briefly explain the job of an enzyme and if it can perform its job more than once.

An enzyme is a protein that initiates and accelerates a chemical reaction in a living organism. Enzymes emerge unchanged—in their original form—when the reaction is complete and thus can be used again and again. Here's how they work.

Why can it be problematic if the shape of an enzyme is changed?

If the shape of an enzyme has changed, the substrate can't fit onto the active site of an enzyme, making it so that the enzyme can't do its job. Slightly modified, non-functioning enzymes are responsible for a large number of diseases and physiological problems.

Define hydrophobic

Repelled by water, as, for example, nonpolar molecules that tend to minimize contact with water. "water fearing"

define denaturation

The disruption of protein folding in which secondary and tertiary structures are lost, caused by exposure to extreme conditions in the environment such as heat or extreme pH.

How is transfat different from saturated and unsaturated fats?

Unsaturated fats that have been partially hydrogenated (meaning that hydrogen atoms have been added to make the fat more saturated and to improve a food's taste, texture, and shelf-life). The added hydrogen atoms are in a trans orientation, which differs from the cis ("near") orientation of hydrogen atoms in the unsaturated fat.

Despite the large variety of proteins found, they are all composed of the same building blocks. By connecting different _______________ together, the result is a unique protein. There are ________ different amino acids available, just as there are 26 letters in our alphabet used to construct different words.

amino acids, 20

Why are carbohydrates so well suited for their primary function

carbohydrates function well as fuel because of their many carbon-hydrogen bonds. As those bonds are broken down and other, more stable bonds (primarily between carbon and oxygen) are formed, a great deal of energy is released that organisms can use.

What is cellulose and where is it found?

complex carbohydrate, indigestible by humans. forms a huge variety of plant structures (trees, cotton, leaves grass). most abundant compound on earth.

Activation energy is required to jump-start a reaction. What is the relationship between enzymes and a reaction's activation energy? Include an example.

enzymes act as catalysts by lowering the activation energy, which causes the reaction to occur more quickly. Enzymes may lower the activation energy by holding substrate molecules in an orientation that stresses bonds that need to break. For example, the enzyme lactase breaks down lactose into galactose and glucose.

Briefly describe the difference between a complete protein and incomplete protein.

foods that are considered "complete proteins" have all the essential amino acids (such as chicken, beef, etc.). Other foods are considered "incomplete proteins", which have some of the essential amino acids, but not all of them (such as rice, lentils, etc.).

Many nucleotides linked together create a strand of DNA. One strand of DNA is bound to a second strand of DNA by _______________ bonds. These two strands then spiral around each other forming the structure of DNA known as a ____________________.

hydrogen, double helix

Give an example of a disaccharide and explain how it's used for fuel

sucrose, also known as common table sugar, is a disaccharide made up of fructose and glucose. to use sucrose, the body must break it down into their component atoms, then the energy that was stored in their chemical bonds is harvested and used.

Why is cellulose an important part of the human diet even though humans can not digest it?

the cellulose in our diet is known as "fiber". as cellulose passes through our digestive system, it scrapes the wall of the digestive tract. Its scraping stimulates the rapid passage of food and of unwanted, possibly harmful products of digestion through our intestines. In this way, fiber reduces the risk of colon cancer and other diseases (but it is also why too much fiber can lead to diarrhea).

explain how waxes differ structurally from fats. what advantages do they provide on the surface of plants and insects?

waxes resemble fats, but have only one long-chain fatty acid linked to the glycerol head of the molecule rather than 3. Because the fatty acid chain is highly nonpolar, waxes are strongly hydrophobic. Because waxes are hydrophobic, they work as a natural coating on the surface of many plants and in the outer coverings of many insects. the waxes prevent loss of the water essential to the organisms' life processes.