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Biological Molecules Flashcards

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1
Q

Water structure

A

-Two hydrogen atoms and one oxygen
-Joined by covalent bonds
-Electrons between atoms not shared equally, meaning O has a negative charge and H has a positive
-This makes it a polar molecule

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2
Q

Hydrogen bonding

A

-Forms between a non bonding pair of electrons on the oxygen atom of one water and the hydrogen
-Much weaker than covalent bonds
-Gives water many of its unique properties

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3
Q

Water as a solvent

A

-Compound with ionic bonding (metals, salts) in water
-Negatively charged O atoms are attracted to positively charged ions, so water molecules surround them
-Creates a cluster of molecules around the ion
-Same with positive H ions and anions

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4
Q

Water as a temperature buffer

A

-Water has a high specific heat capacity
-This regulates temperature changes in cells, and keeps enzyme activity constant

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5
Q

Water in metabolism

A

-A reactant (metabolite) in reactions including digestion, respiration and photosynthesis

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6
Q

Water as a habitat

A

-Rivers and oceans (duh)
-Ice floes, caused by ice being less dense than water due to space between molecules

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7
Q

Water in cohesion

A

-Attraction between polar ends of water molecules
-Able to travel upwards in xylem as molecules stick to each other
-Creates surface tension in ponds

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8
Q

Carbohydrates formula

A

-C(n)H(2n)O(n)
-Function as energy stores, sources or for structure

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9
Q

Monosaccharides

A

-Carbohydrate monomers
-Simple sugars such as ribose and glucose
-All soluble in water

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10
Q

Alpha vs Beta glucose

A

-Alpha has OH on C1 on the same side as that of C4 (below)
-Beta has OH on C1 on the opposite side as that of C4

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11
Q

Disaccharides

A

-Formed by two simple sugars
-Formed during a condensation (water removed) reaction
-Broken down during a hydrolysis reaction
-Achieved by complementary enzyme

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12
Q

Test for reducing sugars

A

-Benedict’s reagent (2Cu(OH)2) turns from blue to brick red
-This is due to the formation of copper oxide

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13
Q

Reducing sugars

A

-Monosaccharides and some disaccharides (with free carbonyl groups)
-Able to donate electrons
-Sucrose is not a reducing sugar as both carbonyl groups (O bonded with two C’s) are in use in bonds

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14
Q

Common disaccharides

A

-glucose + glucose = maltose
-glucose + fructose = sucrose
-glucose + galactose = lactose

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15
Q

Starch

A

-Formed from alpha glucose
-Polysaccharide, structured into amylose and amylopectin
-Found in plants
-Used in energy storage and release

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16
Q

Amylose/Amylopectin

A

-Amylose is formed from unbranched, long glucose chains
-Amylopectin is branched due to 1,6 glycosidic bonds

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17
Q

Glycogen

A

-Formed from alpha glucose
-Branched with shorter chains than amylopectin
-Found in animals
-Used as energy store and release

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18
Q

Cellulose

A

-Formed from beta glucose
-Straight chains, each sugar upside down to the next
-Chains run parallel to each other
-Found in plants
-Forms strong fibres in cell walls for structure

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19
Q

Amino acid structure

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A

H R O
\ l //
N - C-C
/ l \
H H O - H

20
Q

Amino group

21
Q

Carboxyl group

22
Q

R group

Study These Flashcards
A

-Defines which of the twenty amino acids is present.

23
Q

Condensation/Hydrolysis of aminos

Study These Flashcards
A

-A condensation reaction joins together two aminos, in which the H of one and the OH of another is removed. The products are a dipeptide and water.
-A hydrolysis reaction will break a dipeptide back down into amino acids. In processes like digestion this requires enzymes.

24
Q

Lipids

Study These Flashcards
A

-Contain C, H and O
-Insoluble in water.
-Include triglycerides, phospholipids, steroids and waxes.

25
Triglycerides
-Include fats and oils. -Used in respiration, energy storage, insulation, buoyancy or protection. -Made up of three fatty acids and a glycerol C3H5OH3, which are bonded by ester bonds between the H of the glycerol and the OH of the fatty acids.
26
Fatty acid saturation
-Basic fatty acid structure = CnH2nCOOH -Saturated fatty acids have no double bonds between carbons. -Unsaturated fatty acids has one or more double bonds which causes them to bend.
27
Phospholipids
-Similar structure to fatty triglycerides. -One fatty acid is replaced with a phosphate group. -Phosphate group is hydrophilic, fatty acid tail is hydrophobic.
28
Cholesterol
-Steroid -Formula C27H46O -Found in bilayer to enhance the permeability and barrier proteins.
29
DNA structure
-Polymer consisting of two helical chains. -Monomers are called nucleotides. -Each nucleotide contains a pentose (five carbon) sugar, phosphate group and nitrogenous base. -Each strand runs antiparallel to each other.
30
Nitrogenous bases
-Can be A, G, T or C -A and G are purines and have a large nitrogenous base. -C and T are pyrimidines and have a small nitrogenous base. -Purines only bind with pyrimidines, A with T and G with C. -Held together by weak hydrogen bonds that keep double helix intact.
31
DNA replication
-Helicase breaks apart the weak hydrogen bonds between strands, causing them to seperate. -Free nucleotides enter from the nucleoplasm and bind to their complementary bases on the strand. -Bind together to form a completed strand, aided by DNA polymerase. -Creates two separate DNA molecules, each with one original strand and one synthesised one. -This is known as semi-conservative replication.
32
Differences between DNA and RNA
-DNA has thymine as a base while RNA has uracil (does not have the methyl group C5) -DNA is double stranded while RNA is single. -DNA has H on C2 of the pentose sugar (hence deoxy) while RNA has OH.
33
Bonding of DNA strands
Phosphodiester bonds between 5C of one sugar and 3C of another.
34
ATP
-Adenine triphosphate -Chemical energy needed for biological reactions. -Produced aerobically and anaerobically from food.
35
Phosphorylation
-When ADP is bonded with separate phosphate using energy from glucose. -Creates ATP. Most of the energy is stored in the third molecule.
36
Translation
-mRNA in ribosomes. -Read in a series of three bases called codons. -Each codon corresponds to an amino acid. -A tRNA molecules with complementary anticodons carries the written amino acid to the ribosome. -Peptide bonds form between amino acids to form proteins.
37
Transcription
-DNA is copied in RNA. -RNA polymerase binds to the gene in an area known as the promoter region. -RNA polymerase separates strands. -Moves along template strand and adds complementary nucleotides. -Coding strand becomes molecule of mRNA until RNA polymerase reaches a stop codon.
38
Leading/lagging Strand
r-DNA polymerase starts building at the 5' end of the daughter stand. -It can only bind to the 3' strand of a parent strand. -Since the strands are anti-parallel but DNA polymerase can only work in one direction, one strand will be the leading strand, and will be made continuously with the movement of DNA polymerase. -The other strand will be the lagging strand and will run away from the movement of polymerase. This will mean it needs to keep detaching and reattaching, meaning the new strand is built in short segments.
39
Primary structure
-Sequence of amino acids in a polypeptide chain.
40
Secondary structure
-Formation of secondary structures due to hydrogen bonding between carboxyl group and either the amine or hydroxyl group of another. -Alpha helices (NH of one amino acid and CO of one four places above it). -Beta plated sheets (folds in structure, between NH group of one and CO of another)
41
Tertiary structure
-Secondary structures fold up to form a precise three dimensional structure. -Held together by hydrogen bonds, ionic bonds, disulphide bonds between cysteine groups (-CH2-S-S-CH20) and hydrophobic parts of R groups moving towards the centre.
42
Quaternary structure
-More than one polypeptide chain held together by the same forces as in tertiary. -Can include non-amino groups called prosthetic groups.
43
Fibrous proteins
-Form long chains. -Insoluble in water, used in structure and support. -Fibres form a triple-helix of polypeptide chains, held together by hydrogen bonds. -Eg collagen in skin, teeth, bones, blood vessels. -Keratin has lots of disulphide bridges so is very strong, found in nails and hair.
44
Globular proteins
-Tightly folded polypeptide chains, folded so that hydrophobic groups are on the inside. -Water soluble. -Include transport proteins (haemoglobin), enzymes (pepsin digests protein in stomach) and hormones (insulin x2 chains).
45
Glucose properties
-C6H12O6 -Soluble in water (polar) -Reducing sugar
46

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