1
Q
Food tests: Starch
A
test using iodine
simply drop the iodine over the sample is starch is present the sample will turn from brown/yellow to blue/black
2
Q
Food tests: Lipids
A
test usding ethanol and water
add ethannol to the sample, shake the test tube then add water
if lipids are present an emulsion will occur and will turn from clear to a cloudy white
3
Q
Food tests: sugars
A
test using benedicts solution
complete in a water bath add the benedicts solution to the sample if sugar is present the solution will turn from blue to an orange- red
4
Q
Food test: protien
A
test for using buirets solution
add the buiret solution to the sample
if protien is presnt then the sample will turn purple
5
Q
monomer
A
small molecule that form the basic units of polymers
6
Q
Polymers
A
can be long simple strands or highly branched
they are made up of many monomers
7
Q
glucose is a monomer for which polymers ?
A
-cellulose
-starch
-glycogen
8
Q
amino acid is a monomer for which polymers ?
A
protien
9
Q
nucleotides are a monomer for which polymers ?
A
-DNA
-RNA
10
Q
Condensation reactions
A
a molecule of water is removed when monomer–> polymer
11
Q
Hydrolysis
A
breaking of a bond by adding water
12
Q
Monosaccharide
A
single sugars- including glucose, fructose and galactose
13
Q
glucose?
A
monosaccharide with both alpha and beta isomers
14
Q
Glycogen
A
-made from a glucose
-found in animals
-highly branched
-used for storage
15
Q
Cellulose
A
-made from B glucose
-found in plants
-parrallel, long single chain
-hydrogen bonds cross link
-used for cell wall strength
16
Q
Starch
A
-made from alpha glucose
-found in plants
-highly branched
-used for storage
17
Q
alpha glucose
A
the hydroxyl (OH) group on carbon 1is located below the ring
18
Q
beta glucose
A
the hydroxyl (OH) group on carbon 1is located above the ring
19
Q
Starch examples
A
-amylose - hellically coiled 1-4 bonds only
-amylopectin- branched 1-6 bonds, more soluble
-hydrogen bonds- individually weak, collectively strong
20
Q
Structure of starch (TAT)
A
- helical/ spiral shape so compact
- large/ insoluble so osmotically inactive- does not effect water potential
- branched so glucose is easily released for respiration
- large so cannot leave the cell
21
Q
Test for reducing sugars
A
A reducing sugar is able to donate electrons to Benedicts regent which is a solution of copper sulphate
the copper sulphate is reduced to form copper oxide
subjectivekly measured using colour perception
22
Q
Cellulose structure (TAT)
A
structural in plants- main part of cell wall made from beta glucose
-long straight, unbranched chains of beta glucose
-joined by hydrogen bonding
-to form microfibrills
-provides rigidity and strength
23
Q
Lipids
A
-contain C, H, O but less oxygen
-non-polar molecule so are insoluble
-soluble in organic solvents e.g. ethanol
-do not form polymers
24
Q
Triglycerides
A
lipids made from glycerol and fatty acids
joined by an ester bond
-3 fatty acids
-1 glycerol
high ratio of energy storing carbon- so good source of energy
low mass to energy ratio- a lot can be stored in a small space
insolube in water- osmotically inactive- don’t effedct the water potential
release a lot of water when oxidised- fats can be broken down into water- benefits for organisms in a dessert
25
Saturated fats
each carbon atom in the hydrocarbon chain has 4 other atoms bonded to it
saturated fats tend to be solids, as the straight chains allow the molecules to lie close together
26
Unsaturated fats
double bonds between carbon atoms between carbon atoms in the hydrocarbon tail
due to the double bonds the chains 'kink' preventing the molecules from lying close together they therfore tend to be liquids so oils
they typically are triglycerides
27
Phospholipids
polar moleccule- consisting of a polar head and a non-polar tail
hydrophillic head- attracted to water so interacts with it, not attracted to fat , made up of glycerol + phosphate
hyrdophobic tail- attracted to fat and readily interacts with it, but orientates itself away from water, made up of 2 fatty acids
28
Protiens (definition & examples)
Polymer of amino acids joined by peptide bonds formed by a condensation reaction
enzymes
haemoglobin
antibodies
hormones
muscle fibres
antigens
29
Primary structure of proteins
number, type and sequence of amino acids, made up of a linear chain joined with peptide bonds
30
Secondary structure of proteins
alpha helixs due to hydrogen bonding with themselves causing them to coil
beta pleated sheets- hydrogen bonds
31
Tertiary structutre of proteins
alpha helices can be folded even more to form even more complex structures
they do this by 3d folding using disulphide bridges, ionic bonds, and hydrogen bonds
where these bonds occur depends on the primary structure of the protiens
the 3D shape makes each protein specific and distinctive allowing it to be easily recognised by other molecules
32
Quaternary structure
more than one polypeptide chain
e.g. Haemoglobin- 4 polypeptide chain, 4 prosthetic groups- haem group
33
Protein structure- TAT
Polymer of amino acids joined by peptide bonds formed by an amino acid. Primary structure is the number type and sequence of amino acids. Secondary structure is folding of polypeptide chains due to hydrogen bonding either alpha helices or beta pleated sheets are formed. Tertiary structure is 3-D folding due to hydrogen bonding and ionic/ disulphide bridges. Quaternary structure, is two or more polypeptide chains
34
Enzymes- Induced fit model
the active site changes shape as it binds with the substrate (the active site is slightly flexible)
a substrate binds to an active site and both change shape slightly creating an ideal fit for catalysis. enzymes promote chemical reactions by bringing substrates together in an optimal orentation. the strain distorts bonds consequently lowering the activation energy needed to break the bond
35
Describe the induced fit model (TAT)
shape of the active site changes as the substrate binds
this stresses/ distorts/ bends/ applies pressure to the bonds
which lowers the activation energy when the enzyme- substrate ccomplex forms
The shape of the active site is complementary
36
e.g. why does maltase only break down maltose
-tertiary structure/ 3D shape of enzyme so active site is complementary to maltose
37
e.g. why maltase allows induced fit model to take place at normal body temperature
the shape of the active site changes shape as it binds to the substrate
this applies pressure to the bonds
lowering the activation energy when the enzyme- substrate complex forms
38
Enzyme inhibitor
A substance that directly or indirectly intereferes with the functioning of the active site of an enzyme so reducing enzyme activity
39
what are the 2 types of enzyme inhibitors
-competitive inhibitors
-non-competitive inhibitors
40
what is a competitive inhibitor
inhibitors reduce binding of enzymes to substrate so prevent the formation of E-S complexes
inhibitor simillar shape to substrate
binds into active site, can be overcome by adding more substrate
41
What is a non-competitive inhibitor
non competitive inhibitors attach to a site other than the active site
this alters the shape of the active site
the substrate can no longer fit and form enzyme-substrate complexes
cannot be overcome by adding more substrate
42
Describe the structure of DNA
-polymer of nucleotides
-each nucleotide formed from deoxyribose- a phosphate group and an organic/nitrogenous base
-phosphodiester bonds between nucleotides
-double helix held by hydrogen bonds
-between adenine-thymine and cytosine-guanine
43
in DNA what happens when condensation reactions occur
phosphodiester bonds between deoxyribose sugar and one of the nucleotide and phosphate group of another
44
In DNA what are phosphodiester bonds
strong covalent bonds ensuring that genetic code is not broken down
45
How is the structure of DNA efficient for carrying information
- very large molecule
- 4 bases so many combinations
- lots of strong phophodiester bonds
- completmentary base paring
46
Semi- conservative replication
- DNA helicase unwinds DNA
- both strands act as a template
- free nucleotides line up in complementary pairs A-T and G-C
- DNA polymerase joins nucleotides of new strand
- forming phosphodiester bonds
- each new molecule consists of one old strand and one new strand
47
RNA key facts
- not arranged in a helix
- ribose sugar
- uracil pairs wirh adenine
- usually single stranded
- relatively short
48
DNA key facts
- hydrogen bonds between bases
- double stranded
- arranged in a double helix
- deoxyribose sugar
- much longer
- thymine pairs with adenine
49
types of RNA
- rRNA (ribosomal)
- tRNA (transfer)
- mRNA (messanger)
50
ATP
contains a phosphate, ribose, base
- energy containing molecule- drives many proccesses
- another type of nucleic acid- structurally simillar to DNA & RNA
- a phosphorylated nucleotide
- adenine can be combined with one, two or three phosphate groups
51
ATP hydrolysis
ATP is broken down with the use of water to become ADP + Pi
this releases energy which is used in respiration
uses ATP hydrolase- enzyme that catalyses the reaction
52
ATP synthesis
ADP combines with Pi to form ATP + water
it uses the enzyme ATP synthase
condensation reaction, phosphorylation reaction
53
Properties of water TAT
- A metabolite for respiration
- A solvent so reactions can occur
- High heat capacity so buffers the changes in temperature
- Large latent heat of vapourisation so provides a cooling effect
- Cohesion so supports columns of water in plants
- Cohesion so produces a surface tension supporting small organisms
- A solvent so allows the transport of substances
54
what are long stretches of proteins wrapped round
Histones
55
what do chromosomes code for
amino acids in a polypeptide chain or a functional RNA molecule
56
what is an allele
different forms of the same gene
57
what is the position of a gene on a chromosome known as?
locus
58
Genome
all the genetic information in an organism
59
Proteome
the full range of protiens that a cell is able to produce
60
gene
a length of DNA that codes for a single polypeptide or functional RNA
61
what are introns
non-coding sections of DNA-
they make up a large proportion of DNA and control the expression of coding DNA
62
What are exons
coding sections of DNA
63
Eukaryotic DNA
- linear
- nuclear membrane
- condensed and wrapped around protiens called histones
- many chromosomes
- small amounts of DNA in mitochondria/ chloroplasts
- no plasmids
- doubled stranded
64
Prokaryotic DNA
- circular
- no nuclear membrane
- small amounts of DNA in plasmids
- no mitochondria/ chloroplasts
- double stranded
65
Transcription TAT
- hydrogen bonds between bases break
- one DNA strand acts as a template
- free RNA nucleotides align by complementary base paring
- in RNA uracil base pairs with adenine on DNA
- RNA polymerase joins adjacent RNA nucleotides
- by phosphodiester bonds between adjacent nucleotides
- pre-mRNA is spliced to form mRNA
- introns are removed
- mRNA then leaves the nucleus
66
Translation TAT
- mRNA attaches to ribosomes
- tRNA anticodons bind to complementary mRNA codons
- tRNA brings a specific amino acid
- amino aicds join by peptide bonds
- amino acids join together with the use of ATP
- tRNA released after amino acid joined to polypeptide
- the ribosomes move along the mRNA to form the polypeptide
67
in mRNA what base does adenine bind to?
it binds to uracil instead of thymine
68
meosis
cell devision which creates four haploid daughter cells (gametes)
these can then be fused during fertilisation to create a diploid zygote
69
in mammals what gametes are produced in mitosis
sperm and egg
70
in plants what gametes are produced in mitosis
pollen adn eggs
71
Meiosis I
how can varriation occur
- crossing over occurs
- independent segregation- homologous chromosomes randomly arrange themselves on the equator so go to different cellsk
72
Meosis one: prophase one crossing over
crossing over occurs- homologus chromosomes pairs twist around each other causing tension, and breaks. the broken end of the chromatids arm re-joins the new chromatid
73
Meosis one: metaphase 1
all chromosomes lining up along the middle, then homologous chromosomes line up next to each other
74
Meosis one: anaphase 1
causes one coppy of each pair of chromosomes to go to the circumference of the cell
meaning the genetic material has halved- you only have one coppy of each chromosome
75
Meosis one: telophase 1
the nuclear envelope reforms, and the chromosomes decondense
76
independent assortment
homologous chromosomes randomly arrange themselves on the equator and therefore go to different cells
77
meosis 2
a miotic devison, the number of chromosomes stays the same but they split into seperate cells
78
meosis 2: prophase 2
the chromosomes recondense and the nuclear envelope breaks down again
79
meosis 2: metaphase 2
the chromosomes line up individually down the equator of the cell, and the centrioles attach to spindle fibres at the centromere
80
meosis 2: anaphase 2
the chromosomes split, sister chromatids migrate to the poles of the cells
81
meosis 2: telophase 2
the nuclear envelope reforms, the cytoplasm splits to form four haploid daughter cells
82
Meosis overview
- 4 daughter cells made
- enables a species to adapt to a changing environment or colonise to a new environment
- enables species to colonise an area quickly using asexual reproduction
- halves the number of chromosomes
83
mitosis overview
- the original parent cell becomes 2 daughter cell with the diploid number of chromosomes
- when out of control, a cancerous tumor may result
- important for the repair of damaged tissues where now cells must be identical to damaged cells
84
Chromosomal aberrrations
genetic anomalies that occur within an organisms chromosomes
85
Non- dysfunction
when chromosomes or chromatids do not split equally during anaphase. The effect is that resulting gametes from meiosis will not have the correct number of chromosomes.
86
Polyploidy
changes the whole set of chromosomes occur when organisms have three or more sets of chromosomes rather than the usual two
it manly occurs in plants
87
Aneuploidy
- changes in the number of individual chromosomes
- sometimes individual pairs of chromosomes fail to seperate during meosis
- usually results in a gamete haveing one more or one fewer chromosomes
88
aneuploidy fertilisation
fertilisation with a gamete that has the normal number of chromosomes, the resulting zygote will have more chromosomes than that of normal body cells
e.g. down syndrome- extra chromosome
89
Mutations
any change to the base sequence
90
genome
all the genetic information in an organism
91
proteome
the full range a cell is able to produce
92
universal
all living things share the same four organic bases
93
degenerate
one amino acid can be coded for by more than one triplet code
94
non-overlapping
the triplets are all sequential and it matters where you start
95
Additon mutation
one or more extra bases being added to the sequence- point mutation
all subsequent codons are altered- frame shift to the right
can code for different amino acids resulting in a no- functioning protien
96
deletion mutation
- one or more bases is deleted in the sequence- point mutation
- causes a frame shift to the left- different polypeptide chain- non-functional protien
97
Substitution mutation
one base has been changed for a different base, but the numver of bases remains the same and there is no frame shift
only one codon changes, due to degenerate code this could be a silent mutation and still code for the same amino acid so have no impact
98
inverstion mutation
a selection of bases detach from the DNA sequence, but when they rejoin they are inverted so this section of code is back to front
this results in different amino acids being coded for in this region
99
duplication mutation
one or more bases are repeated
causes a change to the amino acid sequence and a frame shift
100
translocation mutation
a section of bases on one chromosome detaches and attaches on to the same or different chromosomes
this is a substantial alteration and can cause significant impacts on gene expression and resulting phenotypes
101
Heredity mutations
if a gamete containing mutation for a type of cancer or genetic disorder are fertilised, the mutation will be present in the new feotus formed
102
Causes of mutations
exposure to mutagenic agents
high energy ionising radiation, such as alpha, beta or gamma radiation
ultra-violet light is not ionising but still high energy so can damage DNA
chemicals (carcinogens) e.g. tabacco can alter the structure of DNA and interfere with transcription
103
Genetic diversity
total number of different alleles within a population (gene pool). greater genetic diversity increases the chances that a population will survive environmental change
104
allele frequency
how often a particular allele occurs within a population
105
reproducative success
how successful organisms are at reproducing. reproducing means benefical alleles are passed on to the next generation changing the allele frequency.
106
Charles Darwin main observations
- varriation exists among species
- all living things produce more offspring than the environment can support
- populations remain fairly constant in size
- the most suited to the enivronment 'fittest' will survive
107
Natural selection
random mutation can produce new alleles of a gene
many mutations are harmful or neutral, but in certain environments the new allele may lead to an increased chance of survival
this leads to increased reproductive success
the advantageous allele is passed on to the next generation
over several generations the new allele will increase in frequency in the population
108
Anatomical adaptions
structural adaptions e.g. beak shape
109
Physiological adaptions
chemical reactions e.g. production of venom
110
Behavioural adaptations
expressed behaviour e.g. penguins huddle
111
Stabilising selcetion
- selection against both extremes
occurs when there is no change in the environment
modal trait remains the san e
standard deviation decreases, as individuals with the extreme trait decrease
e.g. human birth weight
112
directional selection
- one of the extremes has a selection advantage
- occurs when there is a change in the environment
- modal trait changes
e.g. number of antibiotic resistance in bacteria
113
Classification
grouping of living organisms based on how closely related they are
114
Taxonomy
study of classification and the techniques used to classify organisms
115
Phylogeny
study of the evolutionary relationships between organisms
116
Carl Linnaeus
'father' of modern taxonomy
117
Carl Woese
three domain system
118
Six kingdom classification
- protocista
- fungi
- plantae
- animalia
- eubacteria
- archaea
119
Archaea
- single cell prokaryotes- originally bacteria
- differ from bacteria
- genes + protein synthesis- simillar to eukaryotes
- membranes contain fatty acid chain
- no murein in cell walls
- more complex from of RNA polymerase
120
Bacteria
- single celled prokaryotes
- no membrane bound organelles
- ribosomes are smaller than eukaryotes
- cell wall- murein
- single loop of DNA- no histones
121
Eukarya
- a group of organism made up of one or more eukaryotic cells
features:
membane bound organelles
fatty acid chains attached to glycerol by there linkages
not all posses a cell wall, but if they do- no murien
ribosomes are larger than in bacteria and archaea
122
Taxonomic rank
domain
kingdom
class
order
family
genus species
dear king phillip came over from great spain
123
what is the heirarchy between the taxonomic groups
as you move up through each taxon, the number of species increases
124
species
a group of simillar organisims that are able to breed with one another to produce living, fertile offspring
125
Binomial system
nammed binominally using its genus (capital letter) and species (lower case)
if they have the same genus they have a close relationship
126
phylogenetic trees
phylogenetic classification arranges species into groups according to their evolutionary origins and relationships
127
ways to clasify: comparing mRNA bases
mRNA is easier than DNA to isolate from the cells of an organism
if the sequences are simillar it suggests organisms are closely related
128
ways to classify: protien analysis
pure albumin samples are extracted from blood samples taken from multiple species
this sample is then injected into a different rabbit
each rabbit produces antibodies for that specific type of albumen
different antibodies are extracted from the different rabbit and mixed with albumin smaples
the precipitate resulting from each mixed sample is then weighed
129
courtship behave helps individuals to:
- recoggnise members of their own species- produce fertile offspring
- identify a mate that is capable of breeding- both partners need to be sexual mature
- form a pair bond that will lead to successful mating
- synchronise mating so maximum probability of sperm and egg meeting
- become able to breed by bringing opposite sex into physiological state that allows breeding to occur
130
species diversity index
the higher the value, the greater the species diversity
131
impact on biodiversity and methods to reduce impacts of agricultutral practices: hedgerows
decreases biodiversity as it reduces habbitat
maintain and upkeep existing hedgerows
132
impact on biodiversity and methods to reduce impacts of agricultutral practices: monocultures
decreases biodiversity as it replaces natural habitats with just one plant
could create natural meadows on the edge of monocultures
133
impact on biodiversity and methods to reduce impacts of agricultutral practices: pond removal
decreases biodiversity as it removes a habitat
maintain existing ponds, create new ones
134
impact on biodiversity and methods to reduce impacts of agricultutral practices: overgrazing
decresases biodiversity as it reduces the nutrients in the soil
use crop rotation- this allows for nitrogen fixing
135
impact on biodiversity and methods to reduce impacts of agricultutral practices: use of pestercides/ fertilisers
decreases biodiversity as it causes eutrophication which causes algal bloom- fish then die
reduce the use of pestercides
limit the use of pestercides around waterways were leaching or run off can occur
136
impact on biodiversity and methods to reduce impacts of agricultutral practices: lack of intercropping
decreases
intercrop
