biological molecules Flashcards
1
Q
monomers
A
small, building blocks of larger molecules. they can join together through chemical reactions to form polymers. examples include amino acids, nucleotides, and monosaccharides
2
Q
polymers
A
polymers are large molecules made up of repeating subunits called monomers
3
Q
condensation reaction
A
joins two molecules together with the formation of a chemical bond and involves the elimination of a molecule of water
4
Q
hydrolysis reaction
A
hydrolysis reaction breaks a chemical bond between two molecules and involves the use of a water molecule
5
Q
monomer carbohydrates are made from
A
monosaccharide
6
Q
examples of monosaccharides
A
glucose, galactose and fructose
7
Q
bond formed by two monosaccharides
A
glycosidic bond
8
Q
polymer formed by two monosaccharides
A
disaccharides
9
Q
disaccharide formed by condensation of two alpha glucose molecules
A
maltose
10
Q
disaccharide formed by condensation of a glucose molecule and a fructose molecule
A
sucrose
11
Q
disaccharide formed by condensation of a glucose molecule and a galactose molecule
A
lactose
12
Q
two isomers of glucose
A
α-glucose and β-glucose
13
Q
polymer formed by condensation reaction of many glucose units
A
polysaccharide
14
Q
polysaccharides formed by alpha glucose
A
glycogen and starch
15
Q
polysaccharide formed by beta glucose
A
cellulose
16
Q
structure and function of glycogen
A
- alpha glucose
- 1-4 and 1-6 glycosidic bonds
- animals (muscle and liver)
- highly branched (more than starch)
- branches increase SA for hydrolysis back to glucose (ends acted on by enzymes)
- insoluble so won’t impact WP
- compact
17
Q
structure and function of starch
A
- alpha glucose
- 1-4 amylose, 1-4 and 1-6 amylopectin
- plants (chloroplasts)
- amylose is unbranched helix
- compact
- amylopectin is branched
- branches increase SA for hydrolysis back to glucose (ends acted on by enzymes)
- insoluble so won’t impact WP
18
Q
structure and function of cellulose
A
- beta glucose
- 1-4 glycosidic bonds
- plants (cell wall)
- polymers form long, unbranched, straight chains
- chains held in parallel by hydrogen bonds to form microfibrils
- hydrogen bonds increase strength of cell wall
- insoluble so won’t affect WP
19
Q
test for reducing sugars
A
benedict’s reagent
- liquid form of food sample
- benedict’s reagent
- heat in water bath
- colour change from blue to green, yellow, orange or brick red
20
Q
test for non-reducing sugars (sucrose)
A
negetive benedict’s test
- add acid and boil
- cool and alkali to neutralise
- add benedict’s reagent and heat
- blue to green, yellow, orange or brick red
21
Q
test for starch
A
- iodine
- colour change from orange to blue/black
22
Q
two groups of lipids
A
triglycerides and phospholipids
23
Q
structure of triglyceride
A
triglycerides are formed by the condensation of one molecule of
glycerol and three molecules of fatty acid
24
Q
bond formed glycerol and fatty acid (RCOOH)
A
ester bond
25
saturated or unsaturated part of a triglyceride
fatty acid
26
difference between saturated and unsaturated fatty acid
unsaturated have one or more double carbon bond
27
structure of phospholipid
one of the fatty acids of a triglyceride is
substituted by a phosphate-containing group
28
properties of triglycerides
- energy storage due to high ratio of C-H bond compared to C bond
- metabolic water source due to high ratio of H:O, oxidised to create H2O
- do not affect WP because they are large and hydrophobic (insoluble)
- low mass so can be stored without increasing mass and preventing movement
29
properties of phospholipids
- hydrophillic head attracts water because it is charged
- hydrophobic tail repels water and mixes with fat
- two charged regions so are polar
- form phospholipid bilayer
30
test for lipids
emulsion test
- dissolve sample in ethanol
- add distilled water and shake
- cloudy white emulsion forms
31
monomers that make proteins
amino acids
32
strcuture of an amino acid
NH2 represents an amine group, COOH represents a carboxyl group and R represents a side chain (variable group)
33
difference in amino acids
the twenty amino acids that are common in all organisms differ only in their side (variable) group
34
bond formed between two amino acids
peptide bond between carboxyl and amine group
35
formed by two amino acids
dipeptide
36
amino acid polymer
polypeptide
37
contains one or more polypeptides
functional proteins
38
hydrogen bonds
between R groups
39
ionic bonds
between charged R groups
40
disulfide bridges
between cysteine amino acids
41
primary structure
sequence of amino acids in polypeptide chain determined by base sequence of DNA
42
secondary structure
alpha helices or beta pleated sheet due to bending/folding from H bonds
43
tertiary structure
3D shape of protein held in place by ionic, hydrogen and disulphide bonds
44
quaternary structure
protein made of more than one polypeptode chain
45
test for proteins
biuret test
- add biuret
- colour change from blue to purple
46
role of enzymes
tertiary structure proteins which lower activation energy of reactions they catalyse
47
induced fit model
-enzyme's active site slightly changes shape to mold to substrate and become complementary
- E-S complex forms and bonds break, lowering AE
48
properties of enzymes
properties of an enzyme relate to the tertiary structure of its
active site and its ability to combine with complementary
substrate(s) to form an enzyme-substrate complex
49
factors that effect the rate of reaction
enzyme concentration, substrate
concentration, concentration of competitive and of non-competitive inhibitors, pH and temperature
50
competitive inhibitor
competitive inhibitors are molecules that are similar in shape to substrates and bind to the active site. this prevents substrate from binding, a higher substrate concentration can override this.
51
non-competitive inhibitor
bind to enzymes away from active sites, the allosteric site. this causes the active site to change shape so substrate cannot bind regardless of substrate concentration.
52
role of DNA and RNA
deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are
important information-carrying molecules; in all living cells, DNA
holds genetic information and RNA transfers genetic information
from DNA to the ribosomes
53
ribosome formation
RNA and proteins
54
monomer of DNA and RNA
nucleotides
55
nucleotide structure
pentose, a nitrogen-containing organic base and a
phosphate group
56
structure and fucntion of DNA
- stable structure due to sugar phosphate backbone
- double stranded so replication can occur using one strand as template
- weak hydrogen bonds for easy unzipping of the two strands in a double helix during replication
- large molecule to carry lots of information
- complementary base pairing which allows identical copies to be made
57
structure of DNA
DNA nucleotides are deoxyribose sugar, a phosphate group and one of the organic nitrogenous bases adenine, cytosine, guanine or thymine
58
structure of RNA
RNA nucleotides are ribose sugar, a phosphate group and one of the organic nitrogenous bases adenine, cytosine, guanine or uracil
59
bond formed by condensation reaction between two nucleotides
phosphodiester bond between sugar and phosphate
60
structure of DNA molecule
double helix with two polynucleotide chains
held together by hydrogen bonds between specific complementary base pairs
61
function of RNA
to copy and transfer the genetic code for DNA in the nucleus to the ribosomes
62
process of semi conservative replication
- unwinding of the double helix
- breakage of hydrogen bonds between complementary bases in the polynucleotide strands
- the role of DNA helicase in unwinding DNA and breaking its hydrogen bonds
- attraction of new DNA nucleotides to exposed bases on template strands and base pairing
- the role of DNA polymerase in the condensation reaction that joins adjacent nucleotides.
63
structure of ATP
single molecule of adenosine triphosphate (ATP) is a nucleotide derivative and is formed from a molecule of ribose, a molecule of adenine and three phosphate groups
64
enzyme that catalyses the hydrolysis of ATP to adenosine diphosphate (ADP) and an inorganic phosphate group (Pi)
ATP hydrolase
65
effects of ATP hydrolysis
- the hydrolysis of ATP can be coupled to energy-requiring
reactions within cells.
- the inorganic phosphate released during the hydrolysis of ATP can be used to phosphorylate other compounds, often making them more reactive
66
enzyme that catalyses the resynthesis of ADP and Pi during photosynthesis and/or respiration
ATP synthase
67
properties of water
- is a metabolite in many metabolic reactions, including
condensation and hydrolysis reactions
- is an important solvent in which metabolic reactions occur
- has a relatively high heat capacity, buffering changes in
temperature
- has a relatively large latent heat of vaporisation, providing acooling effect with little loss of water through evaporation
- has strong cohesion between water molecules; this supports columns of water in the tube-like transport cells of plants and produces surface tension where water meets air
68
sodium ions in co-transport
glucose and amino acids need help crossing cell membranes. a molecule of glucose or an amino acid can be transported into a cell (across the cell-surface membrane) alongside sodium ions.
69
phosphate ions in DNA and ATP
when a phosphate ion is attached to another molecule, it's known as a phosphate group. DNA, RNA and ATP all contain phosphate groups. it is the bonds between phosphate groups that store energy in ATP. the phosphate groups in DNA and RNA allow nucleotides to join up to form the polynucleotides.
70
mRNA
- messenger RNA
- copy of a gene from DNA
- shorter than DNA
- single stranded
- 3 bases = codon
71
tRNA
- transfer RNA
- transfer amino acid to ribosome
- single stranded
- clover shape from hydrogen bonds
- anticodon
- amino acid binding site
72
difference between DNA and RNA monomers and polymers
monomers
- DNA has thymine, RNA has uracil
- DNA is deoxyribose, RNA is ribose
polymer
- DNA is larger
- DNA is double stranded and RNA is single stranded
73
how does DNA polymerase move oppositely along an antiparallel strand
the active site of DNA polymerase is only complementary to the 3' end of the newly forming DNA strand so the enzyme can only add nucleotides to the new strand at the 3' end.
this means that the new strand is made in a 5' to 3' direction and that 3' DNA polymerase moves down the template strand in a 3' to 5' direction.
because the strands are antiparallel, the DNA polymerase working on one of the template strands moves in the opposite direction to the DNA polymerase working on the other template strand.
74
who discovered the structure of DNA?
watson and crick
75
properties of ATP
- releases small manageable amounts of energy
- small and soluble so easily transported around the cell
releases energy immediately
- can phosphorylate other substances making the more reactive by transferring one of its phosphate groups
- can't pass out of the cell so the cell has an immediately supply of energy
