Chapter 5: Macromolecules

Triglycerides vary with respect to the number of

(b) C atoms in the tails. (c) double bonds in the tails.

What functional features does the phosphate group contribute to the structure of a phospholipid?

* place to attach another small charged molecule * negative charge to interact with water

The table below shows the data collected from the 80,082 women who were part of the Nurses Health observational study of dietary fats from 1980 to 1994. Can you interpret the data and draw any conclusions from the study? Risk of Heart Disease Associated with Increases in Specific Types of Fat Consumed Variable: Saturated fat (each increase of 5% of energy) Relative Risk (RR): 1.17 V: Monounsaturated fat (each increase of 5% of energy) RR: 0.81 V: Polyunsaturated fat (each increase of 5% of energy) RR: 0.62 V: Trans fat (each increase of 2% of energy) RR: 1.93 * A relative risk (RR) of 1 means that there is no difference in risk of coronary heart disease when compared to an equivalent intake of carbohydrates. RR of less than 1 means there is a decreased risk; RR of greater than 1 means there is a greater risk.Data from Hu, F.B. et al. Dietary fat intake and the risk of coronary heart disease in women. New England Journal of Medicine 337:1491-9 (1997). Drag the terms on the left to the appropriate blanks on the right to complete the sentences about the observational study.

1. A relative risk (RR) of 1 means the risk of heart disease is the same compared to an equivalent intake of carbohydrates. 2. An RR greater than 1 means the risk of heart disease is higher compared to an equivalent intake of carbohydrates. 3. An RR less than 1 means the risk of heart disease is lower compared to an equivalent intake of carbohydrates. 4. The RR for monounsaturated fat is 0.81, suggesting that increasing intake of this type of fat by 5% decreases the risk of heart disease. 5. The RR for polyunsaturated fat is the lowest among the fats tested, suggesting that these fats are most beneficial for cardiovascular health. 6. The RR for saturated fat is 1.17. For each 5% increase in energy consumed in this form of fat, there is a 17% increase in heart disease risk. 7. The RR of trans fat is the hghest among the types of fats tested, suggesting that these fats pose the greatest health risk. 8. For each increase of 2% in energy from trans fats, there is a 93% increased risk of heart disease.

How many fatty acids are in a phospholipid?

2

Which of the following pairs of molecules could be joined together by a peptide bond in a dehydration reaction?

A

What are the three components that Nucleotides consist of?

A Five-carbon sugar, A nitrogenous base attached to the sugar's 1'-carbon, and a phosphate group attached to the sugar's 5'-carbon

Which molecule is LESS soluble in water- a fat or a phospholipid? Why?

A fat molecule is less soluble in water because it has three non-polar fatty acids and no polar or charged head like a phospholipid has

Proteins are polymers of _____.

Amino acids

Proteins, which have the diverse functions in a cell, are all polymers of the same kinds of monomers- amino acids. How does the structure of amino acids allow this one type of polymer to perform so many functions?

Amino acids share COMMON chemical groups but have UNIQUE side chains that allow for variation. The common groups are amino and CARBOXYL groups attached to an a carbon. Amino acids link together into a polypeptide via PEPTIDE bonds. Each polypeptide has a unique sequence. The repeated subunits interact with each other via HYDROGEN bonds to establish SECONDARY structures. Interactions between the side chains determine the TERTIARY structure of the polypeptide. The combination allows for an almost infinite number of possible structure, each with a different function.

Carbohydrates- Monomers or components- polymer or larger molecule- type of linkage Fats- Monomers or components- polymer or larger molecule- type of linkage Proteins- Monomers or components- polymer or larger molecule- type of linkage Nucleic acids- Monomers or components- polymer or larger molecule- type of linkage

Carbohydrates- Monosaccharides, Polysaccharides and glycosidic linkage. Fats- Fatty acids, triacylglycerol and ester linkage. Proteins- Amino acids, polypeptides and peptide bond Nucleic acis- Nucleotides, Polynucleotides and phosphodiester linkage

Which part of an amino acid is always acidic?

Carboxyl functional group

Which of the following is a polymer?

Cellulose, a plant cell wall component

Which of these is a phospholipid?

D

A shortage of phosphorus in the soil would make it especially difficult for a plant to manufacture __________.

DNA

The central rule of molecular biology states that _____

DNA is transcribe into RNA, which is translated into protein

The flow of genetic information in a cell goes from ____

DNA to RNA to protein

Which of the following best summarizes the relationship between dehydration reactions and hydrolysis?

Dehydration reactions assemble polymers; hydrolysis reactions break polymers apart

Many scientific studies of dietary health effects are observational. Compared to experimental studies, observational studies can extend over a longer time period, use a more representative population, and measure disease outcomes in addition to risk factors for disease.In an observational study, researchers enlist a study group, and use questionnaires and medical tests to quantify participants' health behaviors and status at the start of the study. The researchers continue to collect data on the participants over many years. Information about each participant's diet, lifestyle habits, risk factors, and disease outcomes are all recorded and analyzed.A landmark study of this type -- called the Nurses' Health Study -- was begun in 1976 with more than 120,000 female nurses. Data from a subset of this group (80,082 women) was used to study dietary fat intake from 1980 to 1994. One goal of that study was to measure the effect of dietary trans fats on cardiovascular health. Do you understand how the Nurses Health observational study of dietary fats was set up and carried out? Sort the statements into the appropriate bins depending on whether they represent factors that varied from participant to participant at the start of this study, factors that were consistent from the start of the study, and factors that were measured in the study.

Factors that varied from the start of the study: 1. smoking status (smoking vs non smoking) 2. percentage of different types of fats eaten 3. activity level 4. total food intake Factor that kept consistent from the start of the study: 1. Sex of participant Outcomes measured in the study: 1. deaths from coronary heart disease 2. number of non-fatal heart attacks

Chances are good that you've heard news reports about trans fats. Chances are better that you've eaten your fair share of these controversial chemicals. But, do you know what trans fats are and why they've been in the news?Around the turn of the 20th century, chemists developed a process for adding hydrogen atoms to the double-bonded carbon atoms of unsaturated fats, producing hydrogenated fats. Partially-hydrogenated fats exhibited several desirable traits -- they did not spoil as quickly as oils and they could withstand repeated reheating during cooking. Initially, such fats, which are cholesterol-free, were also believed to be healthier than saturated fats such as butter. An unfortunate side effect of this hydrogenation process, however, is that it also produces a slightly different form of fat, known as trans fats.By the 1990s, trans fats were found in a wide variety of products, including cookies, crackers, baked goods, and fried foods. But scientific studies began to suggest that trans fats posed a significant health risk, a risk that was possibly even higher than that of saturated fats.In this activity, you will explore two different types of studies that were carried out to learn about the health risks of trans fats- experimental studies and observational studies. Part A - Designing a controlled experimental study One way that researchers study the effects of trans fats on people's health is by setting up controlled experiments. For example, in an experimental feeding trial, participants agree to stick to specific diets that the researchers prescribe. In this case, the researchers might vary the proportions of saturated, unsaturated, and trans fats in the diet of each participant. Throughout the study, the health status of the participants is monitored closely. Suppose that you are a researcher designing an experimental feeding trial. How would you set up your study and what limitations would you face? Drag the labels onto the flow chart to identify the elements and limitations of your experimental design.

Hypothesis- trans fats have a negative effect on cardiovascular health Predication- Eating more trans fats will lead to greater cardiovascular health problems Experiment- Feed some people a diet high in trans fats and feed others a diet low in trans fats Data collection- take blood samples to measure fat and cholesterol levels in the two groups practical limitations: 1. is it possible to completely regulate people's diets? 2. Are other lifestyle factors affecting cardiovascular health? Ethical Limitations: 1. Are we putting individuals' health at risk?

Glucose+Glucose>>____by_____

Maltose+Water (dehydration synthesis)

Generally, animals cannot digest (hydrolyze) the glycosidic linkages between the glucose molecules in cellulose. How then do cows get enough nutrients from eating grass?

Microorganisms in their digestive tracts hydrolyze the cellulose to individual glucose units.

_____ are a major component of cell membranes. They form a bilayer with their hydrophobic tails mingling together and their hydrophilic heads facing the watery environment on both sides of the membrane.

Phospholipids

Which of these is NOT a lipid?

RNA

_____ are lipids with a structure consisting of four fused rings. Many sex hormones are made from this type of lipid.

Steroids

What do DNA, proteins, and fats have in common?

They contain carbonyl groups.

Which statement about unsaturated fats is true?

They have double bonds in their fatty acid chains.

Secondary

This structure is achieved when a protein folds into a compact, three-dimensional shape stabilized by interactions between side-chain R groups of amino acids

True or false? Enzymes in the digestive tract catalyze hydrolysis reactions.

True

_______ is always involved in hydrolysis reactions.

Water

Sugars are molecules that have __________ C:H:O and are called __________.

a 1:2:1 ratio of; carbohydrates

Which of the following statements about the formation of polypeptides from amino acids is true?

a bond forms between the carboxyl functional group of one amino acid and the amino functional group of the other amino acid

When nucleotides polymerize to form a nucleic acid

a covalent bond forms between the sugar of one nucleotide and the phosphate of a second

The peptide bond is ______

a covalent bond joining amino acids together to form a polypeptide

The components of nucleic acids are __________.

a nitrogenous base, a pentose sugar, and a phosphate

Glycogen is _____

a polysaccharide found in animals

Sickle-cell anemia is a disease that is caused by ______ in the ________ of the protein

a single amino acid change; primary structure

Nitrogenous bases are classified as either purines or pyrimidines. Examples of purines are __________.

adenine and guanine

Protein molecules are polymers (chains) of ______

amino acid molecules

Which of the following is NOT attached to the central carbon atom in an amino acid?

an oxygen

A function of cholesterol that does not harm health is its role _____.

as a component of animal cell membranes

Sugars have a(n) __________ group that interacts with a _________ group that forms ring structures when the dry molecule is placed in water.

carbonyl (-C=O); hydroxyl (-OH)

A fatty acid consists of a ____ and a long hydrocarbon chain.

carboxyl group

Plant cell walls consist mainly of _____.

cellulose

Which of these is a polysaccharide?

cellulose

___ is the most abundant organic compound on the earth

cellulose

What are the nucleic acids DNA and RNA made from?

chains of nucleotides

At a conference, the speaker's grand finale was sautéing mealworms (insect larvae) in butter and serving them to the audience. They were crunchy (like popcorn hulls) because their exoskeletons contain the polysaccharide __________.

chitin

Which polysaccharide is an important component in the structure of many animals and fungi?

chitin

The molecules with four fused rings that is found in animal membranes and is the precursor of vertebrate sex hormones is _____

cholesterol

When comparing saturated and naturally occurring unsaturated fats, the unsaturated fats have __________ and are __________ at room temperature.

cis double bonds, lipids

The type of bond that forms to join monomers (such as sugars and amino acids) into polymers (such as starch and proteins) is a(n) __________ bond.

covalent

Identify three possible components of a DNA nucleotide

deoxyribose, phosphate group, thymine

Carbohydrates are used in our bodies mainly for _______

energy storage and release

Which of the following is NOT a polymer?

glucose

A fat molecule is composed of two types of smaller molecules: ____ and fatty acids

glycerol

The highlighted part of this molecule is derived from ...

glycerol

In fat synthesis, _______ and fatty acids combine to make fats plus _______

glycerol; water

The subunits (monomers) in cellulose are linked together by __________.

glycosidic linkages

Phospholipids and triglycerides both ______________

have glycerol backbone

The secondary structure of a protein results from

hydrogen bonds

The secondary structure of a peptide backbone is stabilized by __________ forming either a(n) __________ or a(n) __________.

hydrogen bonds; α helix; β pleated sheet

What holds phospholipids together in a bilayer formation?

hydrophilic and hydrophobic interactions with water

Lipids are diverse compounds that are grouped together because they are

hydrophobic

In the reaction that builds a fat,________ groups react with ________ groups.

hydroxyl; carboxyl

Use the following figure to answer the question. The chemical reaction illustrated ______

joins two fatty acids together

The sex hormones estrogen, progesterone, and testosterone belong to which class of molecules?

lipids

A food company hydrogenated a barrel of fat. The treatment

made the fat less fluid

Which of these is a source of lactose?

milk

A molecule with the chemical formula C6H12O6 is probably a

monosaccharide

The characteristic that all lipids have in common is that

none of them dissolve in water

The building blocks or monomers of nucleic acid molecules are called _____.

nucleotides

Which monomers make up RNA?

nucleotides

Which of these is rich in unsaturated fats?

olive oil

The tertiary structure of a protein includes all of the following interactions except _________ bonds.

peptide

What type of bond joins the monomers in a protein's primary structure?

peptide

Tertiary structure is NOT directly dependent on...

peptide bonds

The lipids that form the main structural component of cell membranes are

phospholipids

What makes lipids/fats hydrophobic?

presence of relatively nonpolar CH bonds

The sequence of amino acids in a protein is called the __________ structure of the protein.

primary

you disrupt all hydrogen bonds in a protein. What level of structure will be preserved?

primary

Which polymers are composed of amino acids?

proteins

The presence of many C-C and C-H bonds causes fats to be...

rich in energy and insoluble in water

This figure is an example of a(n) _____.

saturated fat

The hydrocarbon chains of ______ are not kinked, and thus pack closely together, making animal fats solid at room temperature.

saturated fatty acids

The most unsaturated fats have...

the most double bonds.

One characteristic shared by sucrose, lactose, and maltose is that ________

they are all disaccharides

Primary

this structure describes the alpha-helices and beta-sheets that are formed by hydrogen bonding between backbone atoms located near each other in the polypeptide chain

Quaternary

this structure is the result of two or more protein subunits assembling to form a larger, biologically active protein complex

Tertiary

this structure is the sequence of amino acids in a protein

Macromolecules, the molecules of life, include all of the following except _____

trace elements

________ have one or more double bonds in their hydrocarbon chains and are usually found in vegetable oils

unsaturated fatty acids

In a dehydration synthesis reaction, _______ is always formed as a by-product of the reaction.

water

A dehydration reaction (or condensation reaction) is the process in which

water molecules are produced as a polymer formed from monomers

The molecule illustrated in the figure____

will be liquid at room temperature