Chapter 5-Lecture Flashcards by Sara Richmond

All living things are made up of four classes

of large biological molecules:

carbohydrates, lipids, proteins, and nucleic acids

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_________________: are large molecules and are complex

Macromolecules

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Large biological molecules have unique properties that arise from

the orderly arrangement of their atoms

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Macromolecules are polymers, built from _________

monomers

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Three of the four classes of life’s organic molecules are _____________
____________ ______________ _______________

polymers
Carbohydrates
Proteins
Nucleic acids

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_____________________ are specialized macromolecules that speed up chemical reactions such as those that make or break down polymers

Enzymes

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________________________ occurs when two monomers bond together through the loss of a water molecule

A dehydration reaction

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Polymers are disassembled to monomers by ____________________ , a reaction that is essentially the reverse of the dehydration reaction

hydrolysis

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The Diversity of Polymers

Each cell has thousands of different ____________________

Macromolecules

these vary among cells of an organism, vary more within a species, and vary even more between species

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Carbohydrates include

sugars and the polymers of sugars

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The simplest carbohydrates are _________________, or simple sugars

monosaccharides

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Carbohydrate macromolecules are ________________________ polymers composed of many sugar building blocks
Sugars

polysaccharides,

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______________________ have molecular formulas that are usually multiples of CH2O
Glucose (C6H12O6) is the most common monosaccharide

Monosaccharides

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Monosaccharides are classified by

The location of the carbonyl group (as aldose
or ketose)
The number of carbons in the carbon skeleton

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Though often drawn as linear skeletons, in aqueous solutions many sugars form ___________________
Monosaccharides serve as a_____________________ _______________________________________________

rings

major fuel for cells and as raw material for building molecules

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________________: is formed when a dehydration reaction joins two monosaccharides via a covalent _____________ bond

A disaccharide

This covalent bond is called a glycosidic linkage

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the polymers of sugars, have storage and structural roles

Polysaccharides,

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The architecture and function of a polysaccharide are

determined by its sugar monomers and the positions of its glycosidic linkages

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Starch is to plants __________________ is to animals

glycogen

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___________________: a storage polysaccharide of plants, consists entirely of glucose monomers
Plants store surplus starch as granules within chloroplasts and other plastids

Starch

The simplest form of starch is amylose

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________________ is a storage polysaccharide in animals

Glycogen

Glycogen is stored mainly in liver and muscle cells

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Hydrolysis of glycogen in these cells releases

glucose when the demand for sugar increases

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The polysaccharide ____________________ is a major component of the tough wall of plant cells

cellulose

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Like starch, cellulose is a polymer of glucose, but

the glycosidic linkages differ

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_______________: another structural polysaccharide, is found in the exoskeleton of arthropods _______________: also provides structural support for the cell walls of many fungi

Chitin

______________: are a diverse group of hydrophobic molecules. They are the one class of large biological molecules that does not include true polymers

Lipids The unifying feature of lipids is that they mix poorly, if at all, with water

Lipids are hydrophobic because

they consist mostly of hydrocarbons, which form nonpolar covalent bonds

The most biologically important lipids are

fats, phospholipids, and steroids

Fats are constructed from

two types of smaller molecules: glycerol and fatty acids

Glycerol is

a three-carbon alcohol with a hydroxyl group attached to each carbon

A fatty acid consists

of a carboxyl group attached to a long carbon skeleton

Fats separate from water because

water molecules hydrogen-bond to each other and exclude the fats

In a fat, three fatty acids are joined to glycerol | by an ester linkage,

creating a triacylglycerol, | or triglyceride

The fatty acids in a fat can be all the same or of

two or three different kinds. Fatty acids vary in length (number of carbons) and in the number and locations of double bonds

_______________: fatty acids have the maximum number of hydrogen atoms possible and no double bonds

Saturated

_______________: fatty acids have one or more double bonds

Unsaturated

Fats made from saturated fatty acids are

called saturated fats and are solid at room temperature | Most animal fats are saturated

Fats made from unsaturated fatty acids are

called unsaturated fats or oils and are liquid at room temperature Plant fats and fish fats are usually unsaturated

A diet rich in saturated fats may contribute to

cardiovascular disease through plaque deposits

_______________ is the process of converting unsaturated fats to saturated fats by adding hydrogen

Hydrogenation

Hydrogenating vegetable oils also creates unsaturated fats with _____________________ These trans fats may contribute more than saturated fats to cardiovascular disease

trans double bonds

The major function of fats is ____________

energy storage

Humans and other mammals store their long-term food reserves in

adipose cells | Adipose tissue also cushions vital organs and insulates the body

, two fatty acids and a phosphate group are attached to glycerol

phospholipid

The two fatty acid tails are______________, but the phosphate group and its attachments form a ____________ head

hydrophobic | hydrophilic

When phospholipids are added to water, they self-assemble into double-layered structures called

phospholipid bilayers At the surface of a cell, phospholipids are also arranged in a bilayer, with the hydrophobic tails pointing toward the interior

_______________: are lipids characterized by a carbon skeleton consisting of four fused rings

Steroids

________________: a type of steroid, is a component in animal cell membranes and a precursor from which other steroids are synthesized. A high level of cholesterol in the blood may contribute to cardiovascular disease

Cholesterol,

_____________: include a diversity of structures, resulting in a wide range of functions

Proteins

Proteins account for more than 50% of the dry mass of most cells Some proteins speed up chemical reactions

Other protein functions include defense, storage, transport, cellular communication, movement, or structural support

Enzymes are proteins that act as _____________ to speed up chemical reactions

catalysts

Enzymes can perform their functions repeatedly, functioning as

workhorses that carry out the processes of life

__________________ are unbranched polymers built from these amino acids

Polypeptides

A protein is a biologically functional molecule that consists of one or more ______________________

polypeptides

____________: are organic molecules with amino and carboxyl groups

Amino acids

Amino acids differ in their properties due to

differing side chains, called R groups

Amino acids are linked by covalent bonds called __________________________________

peptide bonds

_________________: is a polymer of amino acids

A polypeptide

Each polypeptide has a unique linear sequence of amino acids, with a _________ end and ________ end

carboxyl end (C-terminus) and an amino end (N-terminus)

The specific activities of proteins result from their intricate three-dimensional architecture

A functional protein consists of one or more polypeptides precisely twisted, folded, and coiled into a unique shape

The sequence of amino acids determines a protein’s three-dimensional structures

A protein’s structure determines how it works

_______________________: of a protein is its sequence of amino acids

The primary structure Primary structure is like the order of letters in a long word Primary structure is determined by inherited genetic information

The coils and folds of _______________ result from hydrogen bonds between repeating constituents of the polypeptide backbone

secondary structure | Typical secondary structures are a coil called an helix and a folded structure called a pleated sheet

_________________: the overall shape of a polypeptide, results from interactions between R groups, rather than interactions between backbone constituents

Tertiary structure,

These interactions include hydrogen bonds, | ionic bonds, hydrophobic interactions, and _________________________________

van der Waals interactions

Strong covalent bonds called ______________ may reinforce the protein’s structure

disulfide bridges

_______________: results when two or more polypeptide chains form one macromolecule

Quaternary structure

__________________: is a fibrous protein consisting of three polypeptides coiled like a rope

Collagen

__________________: is a globular protein consisting of | four polypeptides: two alpha and two beta chains

Hemoglobin

What Determines Protein Structure?

In addition to primary structure, physical and chemical conditions can affect structure

This loss of a protein’s native structure is | called

denaturation Alterations in pH, salt concentration, temperature, or other environmental factors can cause a protein to unravel A denatured protein is biologically inactive

It is hard to predict a protein’s structure from its _________________________

primary structure | Most proteins probably go through several stages on their way to a stable structure

____________________ are protein molecules that assist | the proper folding of other proteins

Chaperonins

With out chaperonins proteins may miss fold and result in

Diseases such as Alzheimer’s, Parkinson’s, | and mad cow disease are associated with misfolded proteins

______________________ store, transmit, and help express hereditary information

Nucleic acids

The amino acid sequence of a polypeptide is programmed by a unit of inheritance called _____________

a gene

Genes consist of DNA, a _____________ made of monomers called ___________________

nucleic acid | nucleotides

There are two types of nucleic acids

``` Deoxyribonucleic acid (DNA) Ribonucleic acid (RNA) ```

DNA provides directions for its own replication DNA directs synthesis of messenger RNA (mRNA) and, through mRNA, controls protein synthesis This process is called

gene expression

Each gene along a DNA molecule directs synthesis of a messenger RNA (mRNA) The mRNA molecule interacts with the cell’s protein-synthesizing machinery to direct production of a polypeptide

The flow of genetic information can be summarized as DNA → RNA → protein

Nucleic acids are polymers called

polynucleotides

Each polynucleotide is made of monomers called

nucleotides

Each nucleotide consists of a

nitrogenous base, a pentose sugar, and one or more phosphate groups

The portion of a nucleotide without the phosphate group is called a

nucleoside Nucleoside = nitrogenous base + sugar Nucleotide = nucleoside + phosphate group

There are two families of nitrogenous bases

Pyrimidines and Purines

____________ | have a single six-membered ring

Pyrimidines (cytosine, thymine, and uracil)

___________________ have a six-membered ring fused to a five-membered ring In DNA, the sugar is deoxyribose; in RNA, the sugar is ribose

Purines (adenine and guanine)

Nucleotides are linked together to build a

polynucleotide

DNA molecules have two polynucleotides spiraling around an imaginary axis, forming a _____________ The backbones run in opposite 5 → 3 directions from each other, an arrangement referred to as ____________ One DNA molecule includes many genes

double helix | antiparallel

Only certain bases in DNA pair up and form hydrogen bonds: adenine (A) always with thymine (T), and guanine (G) always with cytosine (C)

This is called complementary base pairing

RNA, in contrast to DNA,

is single stranded Complementary pairing can also occur between two RNA molecules or between parts of the same molecule

In RNA, thymine is replaced by____________ so | A and U pair

uracil (U)