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BIO150 > Chapter 5 - Structure and Function of Large Biological Molecules > Flashcards

Chapter 5 - Structure and Function of Large Biological Molecules Flashcards

1
Q

How are polymers synthesised

A
  • The reaction which connects monomer to monomer is a Condensation reaction: a reaction which connects a monomer to another monomer with a covalent bond through the loss of a small molecule
  • If a water molecule is lost in the process then its called a Dehydration Reaction: a condensation reaction if it’s a water molecule that is lost
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2
Q

How Polymers are broken down

A
  • Polymers are disassembled to monomers through Hydrolysis(reverse of dehydration)
    • The bonds are broken by the addition of a water molecule
      ○ A hydrogen from water joining to one monomer while the remaining hydroxyl group joins the other monomer
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3
Q

Carbohydrates:

A

includes sugar and polymers of sugar

- Monosaccharides: single sugars
- Disaccharides: double sugars
- Polysaccharides: polymers of sugar
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4
Q

Monosaccharides

A
  • have generally formulas made up of the same molecular unit CH2O
  • diversify based on the way their parts are spatially arranged around asymmetric carbons(a carbon attached to 4 different atoms)
  • are major nutrients for cells and serve as fuel for cellular respiration
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5
Q

Classifications of Monosaccharides

A
  • The location of the carbonyl group determines whether a monosaccharide is an aldose or a ketose
      ○ Glucose is the Aldose because carbonyl group is at the end

          - Fructose, an isomer, is ketose because carbonyl group is in the middle
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6
Q

Disaccharides

A

Consists of two monosaccharides joined together by a glycosidic linkage, which is a covalent bond formed through dehydration between two monosaccharides

E.g. - Lactose, Maltose, Sucrose

need to be broken down into monosaccharides before being used as an energy source by an organism

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7
Q

Lactose Intolerance

A

a condition where lactase, an enzyme which breaks down lactose is missing, and instead lactose is broken down by intestinal bacteria, causing gas and cramping

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8
Q

Polysaccharides Function

A
  • Serve either as storage material which is hydrolyzed when needed or as building materials for the cell
      - The function is determined by the monosaccharides and its position of glycosidic linkages
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9
Q

Storage Polysaccharides in plants:

A
  • Plants store starch as granules within plastids
    • This stored starch can then be hydrolyzed into glucose for a fuel source
    • Starch is composed of glucose monomers being joined by 1-4 glycosidic linkages(linkages at the 1st and 4th carbon)
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10
Q

Storage Polysaccharides in Animals:

A
  • Animals store glycogen mainly in liver and muscle cells
    • This can be broken down to create glucose for a fuel source
      Glucose levels can be depleted if not enough carbohydrates are eaten to replenish
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11
Q

Structural Polysaccharides in Plants

A
  • In plants, cellulose is a major component of cell walls
    • Similar to starch with 1-4 linkages however as the glucose monomers in cellulose form rings in the ‘beta’ configuration(upside down compared to its neighbor)
    • This difference gives cellulose a distinct straight 3d shape allowing it to bond lying parallel to other cellulose molecules, giving cell wall structure
    • Due to ‘beta’ configuration also, enzymes are unable to hydrolyze the linkages
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12
Q

Structural Polysaccharides in ANimals

A
  • Chitin is also important and used by arthropods(spiders, crustaceans) to build exoskeletons
    • Similar to cellulose with ‘beta’ linkages except the glucose monomer of chitin has a nitrogen containing attachment
    • Humans and most animals are unable to digest cellulose due to enzymes being unable to hydrolyze its glycosidic linkages
      • As a result it passes through our digestive tract, and stimulates the release of mucus to aid the smooth passage of food through
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13
Q

Fats:

A
  • Fats are not polymers, but are composed of many smaller molecules joined by dehydration reactions
  • Composed of a glycerol molecule joined to three fatty acid tails by an ester linkage
    • Water separates from fat because its hydrophobic
    • Major function of fats are as energy stores due to hydrocarbon chains being rich in energy
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14
Q

Lipids

A

any of a large group of biomacromolecules which are hydrophobic due to their molecular structure

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15
Q

Fatty Acid

A
  • Has a long carbon skeleton usually 16-18 carbons long
    • At one end is a carboxyl group(C=O-OH / Acid)
    • Rest of the skeleton is a hydrocarbon chain which has relatively non-polar C-H bonds making it hydrophobic
    • Each fatty acid is joined to a glycerol through dehydration reaction
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16
Q

Different Types of Fats: Saturated Fat

A
  • Saturated Fat: all carbons in the hydrocarbon tail are connected by single bond, maximizing the number of hydrogen atoms that can attach
    ○ At room temperature it can solidify due to molecules being able to pack close together
    ○ E.g. lard, butter
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17
Q

Different Types of Fat: Unsaturated Fat:

A

has one or more double bonds between carbons in the hydrocarbon tail, reducing the number of hydrogen atoms which can attach
○ These double bonds are cis double bonds, causing kinks in the chains
○ This makes it liquid at room temperature
○ E.g. oils,

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18
Q

Hydrogenated Vegetable Oils

A

means hydrogens have been added to unsaturated fat foods like peanut butter to prevent lipids from separating out into liquid form by converting it to saturated fat

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19
Q

Adipose Cells

A
  • Humans and mammals stock their long term food reserves in adipose cells which swell and shrink as fat is deposited and withdrawn
    • Adipose tissues also cushion vital organs and insulate the skin
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20
Q

Phospholipids

A

similar to a fat molecule but only has two fatty acid chains attached to the glycerol head while the third is attached on top to a phospholipid, creating an negative charge

- Essential for cells as they make up the majority of cell membranes
- Typically has a smaller charged or polar molecule attached
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21
Q

How Phospholipids arrange themselves into a bilayer

A
  • Has a hydrophilic head, due to the polar nature of the phosphate group and extra molecule, and hydrophobic tail
  • Because the head is polar, and has an affinity for water, the phospholipid orients itself with the tails shielded from water
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22
Q

Steroids

A

lipids characterized by a carbon skeleton consisting of 4 fused rings and are distinguished by different chemical groups

23
Q

Cholesterol

A

a type of steroid crucial in animals as it is a component of cell membranes and a precursor to which other steroids are synthesized

  • Synthesized in the liver and obtained through diet
24
Q

Protein

A

a biologically functional molecule made up of one or more polypeptides, folded into a 3d shape

  • There are thousands of different types of proteins, all constructed from the same 20 amino acids, linked by peptide bonds, in different arrangment
25
Q

Types of Proteins

A
  • Enzymatic: Speed up chemical reactions
  • Defense: protect against disease
  • Storage: stores amino acids
  • Transport: transports substances
  • Receptor Proteins: response of cell to chemical stimuli
  • Hormonal: coordinates organisms activity
  • Contractile and Motor Proteins: create movement
  • Structural: provide shape and support
26
Q

Amino Acids structure

A
  • All amino acids share a common structure of containing an alpha carbon, an amino group(NH2) and a carboxyl group(C=O-OH)
  • What makes the amino acid differ in chemical properties is its Side chain or R group
27
Q

Categories of Amino Acids

A
  • Of the 20 amino acids used to build proteins, they can be grouped into 4 categories based on the properties of their side chains:
    • Nonpolar(hydrophobic)
    • Polar(hydrophilic)
    • Acidic(negative charge)
    • Basic(positive charge)
28
Q

Polypeptides

A

are formed when two amino acids are placed together

  • A dehydration reaction occurs between a carboxyl group and the amino group of another monomer resulting in a covalent bond called a Peptide Bond
  • chemical nature is determined by the kind and sequence of the R group chain
29
Q

Polypeptide backbone

A

The repeated sequence of the carboxyl, amino group and alpha carbon

30
Q

Terms for the ends of a polypeptide Chain

A

N Terminus: the free amino group at the end of the polypeptide chain

C Terminus: the free carboxyl group at the other end of the polypeptide chain

31
Q

What Determines Protein Function

A
  • The function of proteins is determined by their 3d shape which allows them to recognize and bind to other molecules
  • This 3d shape is constructed of multiple twisted polypeptide chains
  • And the way the polypeptide chains twists and folds is based on the amino acid sequence
  • Polypeptide chains can fold spontaneously into functional structure based on bonds formed between amino acids
32
Q

Protein Shapes

A
  • Globular Proteins: roughly spherical
  • Fibrous Proteins: long fibers
33
Q

Levels of Protein Structure: Primary

A

the linear sequence of amino acids

34
Q

Level of Protein Structure: Secondary

A

the presence of alpha helixes and beta sheets

- Structures are as a result of hydrogen bonds between certain amino acids in the polypeptide backbone
- A helix is the formation of a hydrogen bond between every 4th amino acid
- B sheets is formed by hydrogen bonds between two parallel polypeptide chains
35
Q

Level of Protein Structure: Tertiary

A

the 3d shape of a singular polypeptide chain
- Forms due to interactions between the R groups

- Hydrophobic Interaction: hydrophobic R groups end up in the middle of the structure, which allow van de waal bonds to help hold them together while the hydrogen bonds keep polar and ionic stabilize the rest of the structure

- Disulfide Bridges also reinforce the shape of the structure by binding two R groups with sulfhydryl groups together
36
Q

Level of Protein Structure: Quaternary

A

3d shape of two or more polypeptide chains

37
Q

Denaturation:

A

when a factor can affect or disrupt the bonds in a protein, it can affect the shape and therefore the function

38
Q

Intrinsically Disordered Proteins

A

proteins which don’t have a distinct shape until they interact with a target protein or other molecule

39
Q

Sickle Cell Disease

A

an inherited blood disorder is caused by the substitution of an amino acid(valine) instead of the normal one(glutamic acid) at the position of the sixth amino acid in hemoglobin which is responsible for carrying red blood cells

  • Normal hemoglobin cells are disc shaped but abnormal hemoglobin aggregate into chains which clog blood vessels
40
Q

Nucleic acids:

A

polymers made from monomer nucleotides joined by phosphodiester bonds
- They are genes which determine the primary structure of amino acids

41
Q

Types of Nucleic Acid

A
  • Deoxyribose nucleic acid: usually double stranded helix which consists of nucleotide monomers a deoxyribose sugar and a nitrogenous base of either adenine, Cytosine, Guanine and Thymine
    • Capable of being replicated
  • Ribonucleic Acid: usually single stranded with a ribose sugar and nitrogenous bases of either cytosine, guanine, adenine and uracil
    • Functions in protein synthesis
42
Q

Gene Expression basic Steps

A
  • DNA provides direction for its replication and directs RNA synthesis
  • Through RNA, it controls protein synthesis
  • DNA is the genetic information inherited from parents
  • When a cell reproduces, DNA molecules are copied and passed along
  • A gene synthesizes mRNA which exits the nucleus and interacts with ribosomes to produce polypeptides
43
Q

Components of a nucleotide:

A

composed of a 5-carbon sugar(pentose), a nitrogenous base and to 1-3 phosphate group

44
Q

Families of Nitrogenous Bases:

A
  • Pyrimidine: cytosine, Thymine and Uracil
  • Purines: adenine and Guanine
45
Q

Making of Nucleotide Polymers

A
  • The linkage of nucleotides into a chain involves a condensation reaction
    • Adjacent nucleotides are joined by a phosphodiester bond
    • A phosphate group which covalently links to the sugars at the 5’ end
  • The polynucleotide has a built in directionality along its sugar phosphate going from 5’ to 3’ carbon
46
Q

Sugar Phosphate Backone

A
  • The repeating joining of sugar to phosphates creates the sugar-phosphate backbone of nucleotides
  • Nitrogenous bases are not part of this backbone
47
Q

Structure of DNA

A
  • Has two polynucleotide strands running in opposite directions to form a double helix\
  • Antiparallel due to the 5’-3’ strands running in opposite directions in DNA
  • Sugar-phosphate backbone is on the outside of the helix while the bases are on the inside
  • Strands are held together by hydrogen bonds between paired bases
  • In DNA only G and C pair, and A and T pair

The two DNA strands are complementary, both strands are counterparts for each other

48
Q

Structure of RNA

A
  • Single stranded
  • Can form complementary base pairs between two regions in two RNA or two stretches in the same RNA
  • runs 5-3’ way
  • In RNA, Adenine pairs with Uracil, Guanine still with Cytosine
49
Q

Bio Informatics

A

The use of computer software and other computational tools that can handle and analyze these large data sets

50
Q

Genomics:

A

analyzing large sets of genes or analyzing whole genomes of species
- Genomics has helped confirm evidence for evolution as well as discover relationships among different groups of organisms

51
Q

Proteomics

A

analyzing large sets of proteins, including their sequences

52
Q

How DNA is used to measure Evolution

A
  • We expect two species which appear to be closely related anatomically to also share greater proportions of their DNA and protein sequences
  • DNA contains the heritable information in genes which provide evidence of an organisms hereditary background
53
Q
A

BIO150 (19 decks)

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