CH 5 Structure and Function of Large Bilocical Molecules

8/3/2019 CH 5 Structure and Function of Large Bilocical Molecules

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Ch 5: Structure and Function of Large Biological Molecules

verview: Molecule of

ife

ey Concepts

5.1: Macromolecules areolymers built from

monomers

ynthesis and Breakdown

f Polymers

iversity of Polymers

5.2: Carbohydrates serve

s fuel and buildingmaterial

ugars

aldose ketoses

All living things are made up of 4 classes of large biological molecules (the big 4):carbohydrates, lipids, proteins, and nucleic acids.

Small organic cell combine to make larger moleculesMarcromolecules- large molecules composed of thousands covalently connected atomMolecular structure and function inseparable5.1 marcromolecules are polymers, built from monomers5.2 carbohydrates serve as fuel and building material5.3 lipids are diverse group of hydrophobic material5.4 proteins include a diversity of structures, resulting in a wide range of functions5.5 nucleic acid store, transmit, and help express hereditary informationPolymer- long molecule consisting of many similar building blocksThe small building-blocks are called monomer3 of 4 classes of lifes organic molecules are polymers

-Carbohydrates-Proteins

-Nucleic acids

Dehydration reaction occurs when 2 monomers bond together through threw loss ofwater

Polymers break apart to monomers by hydrolysis, reactions that is reverse of dehydraEnzymes are macromolecules that speed up reactionEach cell has thousands of different macromoleculesMacromolecules vary with cells, vary more with a species, vary much more between

species

Immense variety of polymers can be built from a small set of monomersCarbohydrates include sugars and polymers of sugarsSimplest carbohydrates are monosaccharide, or single sugarsCarbohydrate molecules are polysaccharides, polymers composed of many sugar buil

blocks

Monosaccharide have molecular formula that are usually multiples of CH2OGlucose (C6H12O6) is most common monosaccharideMonocc are classified by

-locations of carbonyl group (as aldose or ketose)- number of carbons in carbon skeleton

Though written as linear skeleton, sugars form ringsMonocc serve as major fuel for cells as raw material for building moleculesDisaccharide forms as dehydration reaction joins 2 monocc through a glycosidic link

1-4glycosidic

linkage

glucose glucose maltose

(a) dehydration reaction in the synthesis of maltose


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olysaccharides

torage Polysaccharides I

torage Polysaccharides II

tructural Polyscc I

tructural Polyscc II

5.3: Lipids are a diverseroup of hydrophobic

molecules

) Fats

1-2

glycosidiclinkage

glucose fructose sucrose

(b) dehydration reaction in the synthesis of sucrose

Polysaccharides, polymers of sugars, have storage and structural rolesStructure and function of polyscc are determined by sugar monomers and position of

glycosidic linkage

- Storage- starch (plants)- Storage- glycogen (animals)

- Structure- cellulose (plants)- Structure- chitin (insect and fungi)

Starch, storage polyscc of plants, consists entirely or glucose monomersPlants store surplus starch as granules within chloroplasts and other plastidsGlycogen is a storage polyscc in animalsHuman and other vertebrates store glycogen in liver and muscle cellsThe polyscc celluse is a major component of the tough wall of plant cells and formed

microfibrils

Like starch, cellulose is a polymer of glucose, but glycosidic linkage differ based on2ring forms for glucose: alpha (, helectical) and beta (, straight)

Starch: 1-4 linkage of glucose monomers cellulose: 1-4 linkage of glucose monom

Chitin is found in the exoskeleton of arthropodsChitin also provides structural support for cell wall in many fungiLipids are class of large biological molecules that dont form polymersUnifying feature of lipids have little of no affinity to water (hydrophobic) because the

consist mostly of hydrocarbons, which form non-polar covalent bonds

Important lipids are:- Fats

- Phospholipids- Steroids

Fats are constructed from glycerol and fatty acids(arent polymers)

Glycerol is a 3-C alcohol with and OH on each CFatty acids consists of a COOH on a long carbon

skeleton

Fats arent miscible with water because dont readily


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2) Phospholipids

3) Steroids

5.4: Proteins have manyructures, resulting in a

ide range of functions

form H-bonds

Fatty acids vary in length(# of C) and in # and location of double bondsSaturated fatty acids have the maximum # of hydrogen atoms possible and no double

bonds

Unsaturated fatty acids have one or more double bondsSaturated fats made from saturated fatty acids and are solid ate room temp

- diet rich in saturated fats may help to cardiovascular disease through plaque zones

Unsaturated fats made from unsaturated fatty acids and are liquid at room temp- hydrogenation is process of converting unsaturated fats to saturated fats by adding

- hydrogenating vegetable oils also create unsaturated fats with trans double bonds

Fats.plus

Major function of fats is energy storageHuman store fat in adipose tissue that also cushions vital organs and insulated bodyCertain unsaturated fats arent synthesis in body and need outside sources

In a phospholipids, 2 fat acids and a phosphate group are attached to glycerol2 fatty acids tails are hydrophobic, but the phosphate group and its attachments form

hydrophilic head

When phospholipids are added to wthey self assemble into a bilayer,with the hydrophobic tail into theinterior, this is what makes up th

cell membrane

Phospholipids are major part of a cmembrane

But more than just phospholipids cbe found in the membrane

-sterols-proteins

Steroids are lipid characterized by a carboskeleton of four fused rings

Cholesterol, a major steroid, in a componin animal cell membranes

Although essential, high level of cholestein blood contribute to cardiovascular

disease

Proteins make up for more than 50% of the dry mass of most cellsProteins are polymers constructed from amino acidsProteins functions include structural support, storage, transport, cellular communicati

movement, and defense against foreign substances


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olypeptides

mino Acid

Enzymes are a type of protein that act like a catalyst to speed up chemical reactionsEnzymes can form functions repeatedly, functioning like workhorses that carry out

processes of life

Polypeptides are polymers built from the same set of 20 amino acids a protein is abiologically functional molecule consisting of one or more polypeptides

Amino acids are organic molecules with carboxyl and amino groupsAmino acids differ in their properties due to differing side chains, called R

groups

Amino acids are linked by peptide bonds forming a polypeptidePolypeptides range from a few to more than a thousand monomersEach polypeptide has a unique linear sequence or amino acids with a carboxyl at the e

(C-terminus) and an amino acid (N- terminus)

Sequence of amino acids determine a proteins 3D structure and structure determinesfunction including its interaction with other molecules


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our levels of protein

ructure

rimary Structure

econdary Structure

ertiary Structure

uaternary structure

ickle-cell disease: a

hange in primary structure

What determines proteinructure?

rotein folding in a cell

5.5: Nucleic acids store

nd transmit hereditarynformation

Primary structure of a protein is its unique sequence of amino acidsSecondary structure, in most proteins, consists of coils and folds in polypeptide chainTertiary structure is determined by interactions among various side chains (R groups)Quatemary structure results when a protein consists of multiple polypeptide chainsPrimary structure- sequence of amino acids in a protein, is like the order of letters in a

long word

Primary structure is determined by inherited genetic info

Coil and folds of secondary structure result from hydrogen bonds between the AA unof the backbone

Typical secondary structure are a coil ( helix) ad a folded structure ( pleated sheetTertiary structure is determined between groups ( not AA)Collagen is a fibrous protein consisting of three polypeptides coiled like a ropeQuaternary structure result when 2 or more polypeptide chains form on macromolecuHemoglobin is a global protein consisting of four polypeptides: 2 alpha and 2 beta chSlight change in primary structure can affect a proteins structure and ability to functi

Adding to primary structure, physical and chemical conditions affect structureAltering ph balance, salt concentration, temp, or other environmental factors can caus

protein to unravel

Loss of proteins native structure is called denaturationDenatured protein is biologically inactiveHard to see a proteins structure just from its primary structure, and proteins usually g

threw several states on their way to a stable structure

Chaperonins are protein molecules in charge of properly folding other proteinsScientist use x-ray crystallography to determine a proteins structureBioinformatics uses computer programs to predict protein structure from amino acid

sequence

Amino acid sequence of a polypeptide is programmed by a unit of inheritance called gene- genes are made of DNA, a nucleic acid

2 types of nucleic acids:- deoxyribonucleic acid (DNA)- ribonucleic acid (RNA)

DNA provides direction for it own replicationDNA directs synthesis of

-messenger RNA (mRNA) control

protein synthesis and AA sequence ofpolypeptide- Ribosomal RNA (rRNA) forms

ribosomes that synthesize polypeptides- Transfer RNA (tRNA) aids rRNA in

synthesizing polypeptides


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he structure of Nucleic

cids

ucleotide monomers

ucleotide polymers

tructure of DNA and

NA molecules

Nucleic acids are polymers called polynucleotides composed of monomers callednucleotides

Each nucleotide consists of a nitrogenous base, a pentose sugar, and a phosphate grou(nucleotide without he phosphate group is called a nucleoside)

Two families of nitrogenous bases:- Pyrimidines (C,T,U) have a single six-membered ring- Purines (A,G) have a six-membered ring fused to a five-memebered ring

In DNA, the sugar is deoxyribosome; in RNA, the sugar is ribosomeAdjacent polymers are joined by covalent bonds that form between the OH group on

3rd

carbon of on mucleotide and the phosphate on the 5th

carbon on the next

These links are backbones of sugar-phosphate units with nitrogenous bases asappendages

Sequence of bases along a DNA or mRNA polymer is unique for each geneDNA

- DNA molecules have two polynucleotides spiraling around an imaginary axis,forming a double helix

- in DNA double helix. Two backbones run in opposite 5 -> 3 directions from eac

other, and arrangement referred to as antiparallel- on DNA molecule includes many genes

- nitrogenous bases in DNA pair up from hydrogen bonds in a complinetary way:- Adeline (A) always with Thymine (T)

- Guanine (G) always with Cytosine (C)

RNA- usually exists as single polynucleotide chains

- In RNA, thymine is replaced by uracil (U) so A and U pair

- complementary pairing occur in and RNA molecule


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NA and proteins as tapemeasures of evolution

ou should now be able to

Linear sequence in DNA molecules are passed from parent to offspringTwo closely related species are more similar in DNA than are more dinstantly specieMolecular biology can be used to asses evolutionary kinship

Biology 1B

1) list and describe four major classes of molecules2) describe formation of a glycosidic linkage and distinguish between

monosaccharide, disaccharides, and polysaccharides3) distinguish between saturated and unsaturated fats and between cis and trans fa

molecules4) describe the four levels of protein structure5) distinguish between following pairs: pyrimidine and purine, nucleotide and

nucleoside, ribosome and deoxyribose, and the 5 end and the 3 end of a

nucleotide

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CH 5 Structure and Function of Large Bilocical Molecules