module 2 Flashcards
foundations (296 cards)
1
Q
what are the 7 properties of water
A
metabolite, high specific heat capacity, solvent, high latent heat of vaporisation, reacant, strong cohesion and surface tension
2
Q
what are the chemical properties of water
A
polar molecule, oxygen attracted to electrons stronger than hydrogen so it is slightly more negative and hydrogen is slightly more positive, due to unequal share of electrons
3
Q
what are monomers
A
small units which link to form long polymer chains
4
Q
what are polymers
A
long chains consisting of monomers bonded together
5
Q
what is condensation
A
reaction which joins monomers by chemical bonds, eliminating a water molecule as a result
6
Q
what is hydrolysis
A
a reaction where molecule’s bonds are broken and a water molecule is formed
7
Q
what is a carbohydrate
A
molecules consisting of carbon, hydrogen and oxygen
8
Q
what is a saccharide
A
long chains of sugar
9
Q
what are the types of saccharides
A
monosaccarhides, disaccharides and polysaccharides
10
Q
how are di/polysaccharides formed
A
monosaccharides bonded by glycosidic bonds in condensation reaction
11
Q
what is glucose
A
monosaccharide with 6 carbon atoms, main substrate for respir\ation, two isomers-alpha and beta
12
Q
what is the difference between alpha and beta glucose
A
in alpha glucose, the hydroxyl (oh) is at the bottom on the end and h is on top, in beta the hydroxyl is on the top of the end and h is at the bottom
13
Q
what are the disaccharides and what are their structures
A
maltose-two alpha glucose
sucrose-one alpha glucose and fructose
lactose-one alpha glucose and galactose
cellbiose-two beta glucose
14
Q
what are the polysaccharides
A
glycogen + starch (both formed by alpha glucose), cellulose (formed by beta glucose), all formed when gluvose units join by condensation
15
Q
what is glycogen
A
alpha glucose, 1-4 and 1-6 glycosidic bonds, large number of side branches- quickly releases energy, large but compact so good for energy storage
16
Q
what is starch
A
stores energy in plants, two types-amylose and amylopectin, joined by glucose molecules
17
Q
what is amylose
A
unbranched chain of glucose, 1-4 glycosidic bonds, coiled, very compact, energy store
18
Q
what is amylopectin
A
branched glucose, 1-4 and 1-6 glycosidic bonds, side branches, rapidly digestedby enzymes. energy released quickly.
19
Q
what is cellulose
A
long, unbranched chains of beta glucose joined by glycosidic bonds, microfibrils (strong threads) of long cellulose chains joined by hydrogen bonds, strucural support of plant cell walls.
20
Q
what is glycogens function in the body
A
stored as granules in the muscle and liver, broken down to alpha glucose, used for respiration, forms atp and is a source of energy
21
Q
what is a protein
A
long chains of amino acids form large polymers
22
Q
functions of amino acids
A
structural, catalytic, carriers and pores
23
Q
process of amino acids
A
covalent bond that forms when two amino acids are joined by a condensation reaction with the loss of one water molecule, the bond may be broken by a hydrolysis reaction
24
Q
strcuture of protein
A
1 amine group, r group, central carbon, carboxyl group
2 amino acids have a peptide bond
25
what is the nucleus composed of and its function
large organelle, surrounded by nuclear envelope, pores and chromatin and nucleolus
stores genetic material, control dna transcription, dna instructions to make protein, chromatin and protein condense into chromosomes
26
nuclear envelope
double membrane with fluid that surrounds nucleus, pores=protein complexes with channel in centre, separates nucleus contents, pores enable large structure to leave nucleus while other substances enter
27
nucleolus
dense, spherical, no membrane, protein and mrna, as well as ribosomal rna, combines protein to form ribosomes for protein synthesis
28
cytoplasm
substance between plasma memebrane and nucleus, cytosol is the liquid within, organelles float in it, hold internal structure in place, protects from damage, stores molecule for processes while hosting
29
rough endoplasmic reticulum
flattened membranes enclose fluid filled sacs=cisternae, coated in ribosomes, form channel for substances, polypeptide chain fold in side lumen, large surface area for ribosomes to assemble, amino acid to proteins from transport to golgi apparatus
30
smooth endoplasmic reticulum
flattened membrane, cisternae, no ribosomes, make lipids, phospholipids for plasma membrane, contains enzymes that detoxify lipids
31
vesicle
small fluid filled sac in cytoplasm surrounded by single membrane, transports substance in and out cell
32
golgi apparatus
stack of cisternae, secretory vesicles= bring materials to and from, modifies lipid to and from rer, secretion to cell membrane via vesicle, lysosomes synthesis
33
mitochondria
spherical, rod shaped or branched, 500 to 300 nm, double membrane, fluid flilled space=matrix, inner membrane folded to cristae, site of aerobic respiration, atp production, self replicating,
34
chloroplasts
large organelles, 400 to 1000nm long, double outer membrane, complex arrangement, of internal form thylakoids, stacks= grama, joined by intergranal lamellae, stroma=fliud filled matrix, site of photosynthesis, grana=light energy trapped, makes atp and water spilt to ions, stroma=atp makes carbohydrates
35
vacoule
surrounded by tonoplasts, fluid, filled with water, solutes and maintain cell stability, full when pushed against cell wall=turgid
36
lysosomes
round organelle, single membrane, no clear internal structure, small bags from ga, hydrolytic and digestive enzymes, engulf old membranes, digest and recycle, abundant in phagocytes
37
plasma membrane
surface of animal cells, inside cell wall, lipid and protein, barrier, different permability, to different biological membranes, protein carriers, pump substance in and out
38
cilia
small, hair like, outer membrane, 9 pair ring two in middle, microtubules, allow cilia to move, substance along cell surface, large surface, on body cells as antenna and contain environment receptors
39
undulipodia
flagellum, long cilia, small, hair like, cell surface, 9 pair ring and 1 in middle microtubules, contract to move, prokaryotic different internally
40
ribosomes
small spherical organelle, 20nm diameter, 2 subunits each, proteins and ribosomal dna, attach to rer, proteins exported out cell, free floating cytoplasm, make protein inside cell
41
centrioles
two bundles of microtubules, 90 degrees each, microtubules of tubulin protein subunits form cylinder, separates chromosomes, cell divison, motor proteins move along, tubulin threads, pull chromosomes apart, involved in cilia and flagella formation
42
cell wall
rigid structure, cellulose fibres, strong, prevent cell burst, strength and support, maintain shape, permeable due to plasmodesmata (pores within calls), allow solution through
43
types of proteins
gobular and fibrous
44
gobular protein characteristics
roughly circular, irregular , range of r groups, structural function, haemoglobin, enzymes, insulin, immunoglobulin, soluble in water
45
fibrous characteristics
long strands, regular, repetitive, limited range of r groups, physiological and functional function, ccollagen , keratin, myosin, actin, fibrin, insoluble in water
46
pepsin function
enzyme cartalyses breakdown of starch into maltose, single chain of 327 amino acids, a helix and b pleated sheets, fold into symmertical tertiary, hydrogen and disulphide, no quaternary
47
insulin function
hormones affected by pancreas to lower blood glucose levels, a chain has 21 amino acids, b chain has 30 amino acids, a helix, b pleated, disulphide links, hydrophilic r groups on outside, two polypeptide chains, disulphide bonds, highly soluble, complementary insulin groups
48
collagen function
molecule size; insoluble, too long to be dissolved
3 stranded, high tensile strength; 3 polypeptide chains, held by h chains, with stand pulling
glycine, compact, 1 h in r group; every 3rd amino acid in polypeptide,
lysine; formation of fibres, face outwards, covalent bonds, between lysine r group of different collegen molecules
unbranched, elastcity and strength, in tendons, cartilage, arterial wall, skin, straight chains, a helix b pleated, no tertiary,
49
conjugated
has non protein group attatched, haemoglobins haem group (prosthetic)
50
what are triglycerides
marcomolecules, carbon, hydrogen and oxygen, soluble in alcohol, insulators,
51
what are the three types of triglycerides
triglycerides, phospholipids and steroids
52
what tricelyrides consisting of
3 fatty acids and 1 glycerol
-alcohol, -oh, c3 h8 o3
-carboxylic acid -cooh
53
what is esterification
condensation, the -oh and -ho bond to form 3 waters, leaaving 3 ester bonds between glycerol and fatty acids
54
functions of tryglycerides
energy source for respiration, energy store for fat, insulation, bouyency as it is denser than water, protects delicate organs
55
types of fatty acids
monounsaturated (one double bond c=c), polyunsaturated (multiple double bonds,) saturated (no double bonds)
56
what is a phospholipid
modified tryglyceride, contains a phosphate/hydrophilic head, glycerol, two fatty acids/hydrophobic tail, (non polar, HC crown)
57
what is the process of protein transport- exocytosis
proteins are produced in the ribosomes, proteins produced surface on rer, and are folded and produced, transported to golgi apparatus, in vesicles then are modified, then transported where required
58
function of cytoskeletons
allows cell to move, provides support and strengthens cell, give cell its shape and helps to change shape, holds organelles in place
59
what are the parts of the cytoskeleton
microtubules, microfilaments and intermediate filaments
60
what does the microtubules do
globular proteins polymerise to form tubes that are scaffolding like that determines the shape of the cell, tracks for movement for organelles like the vesicles and is in spindle fibres for cytokinesis
61
what do microfilaments do,
contractile fibres that form from actin, responsible for cell movement, and cell contraction during cytokinesis,
62
what do intermediate filaments do
mechanical strength in cells that help maintain intergrity, hold cells together
63
how does the cytoskeleton help with cell movement
for phagocytes, the actin filaments activity means it changfes lengths at a rate subunits are not symmetrical when subunits are added or removed at one end, it effects the direction it moves in, these different rates are determined by concentration of subunits= treadmilling
64
what is one of the important subunits in the microfilaments
dynein
65
what are phospholipids
hydrohilic head, hydrophobic tail, amipathic, micelle, bilayers, the tail faces outward, middle=hydrophobic, forms a barrier, partially permeable membrane, only allows small non polar molecules
66
what is cholesterol
it is a hydroxyl group+HO+ hydrocarbon rings + hydrocarbon tail, type of sterol, 4 hydrocarbon rings, formed in liver and intestines, formation of cell membranes, between phospholipids to make them more stable, regulates fluidity, thermoregulation, inside steriod hormones, synthesise bile
67
what is a sterol
type of lipid, found in cells, 4 carbon ring, hydroxyl group on end, attach to hydrocarbon, polar hydroxyl attached
68
what is protein synthesis
-dna strand opens up to form mRNA
-leaves mnucleus and goes to cytoplasm
-mRNA binds to the riboosomes
-polypeptide chain fiorms
-RNA protein is folded
-vesicle containing the proteinbuds off it
-vesicle fuses with the golgi apparatus
-GA modifiesthe protein
-vesicle buds off again
-vesicle fuses with the cell membrane
-forms secretroy vesicle and leaves through exocytosis
69
what is exocytosis
bulk organelles leave via the cell membrane
70
endocytosis
bulk organelles enter via the plasma membrane
71
what is non reducing sugars
not capable of being oxidised cause reduction without hydrolysis
72
what is reducing sugars
capable of being oxidised cause reduction without hydrolysis
73
results of reducing sugars test
brick red=most concentrated with reduced sugars
orange=less concentrated
green=even less concentrated
blue=not concentrated at all
74
types of non reducing sugars
sucrose
75
types of reducing sugars
glucose and fructose
76
how are non reducing sugars tested
negative reducing sugar result first, then use hcl, same system as reducing sugars
77
bacterial cell components
cell wall, capsule, nucleoid, plasma membrane, mesosome, ribosomes small than eukaryotes, cytosplasm, bacterial flagellum, no nucleus,flagella and plasmid not alwasys present, no mitochondria
78
why does bacterial cells not have mitochondria
the atp cynsthase protein is on the ribosomes meaning they can make atp
79
what is nucleoids
nucleus like, irregularly shaped, genetic material, single circular, control transcription
80
what are mesosomes
no mitochondria, plasma membrane folded, have embedded enzymes, responsible for atp respiration,
81
what does the cell wall do in bacteria
celluluose, and peptidoglycon, provide strength and support to cell shape,
82
plasmids
small, circular, double stranded, distinct from chomosomal dna, provide bacteria with genetic advantages
83
capsules
structure outside cell wall, made of polysaccaharides, virulent, ehances disease by prev eventing phagocyotsis, bacterial adhesion to surface to increase colonisation
84
endosymbiosis
mitochondria and chloroplasts, were once free living bacteria absorbed into larger cells, similar size and length to bacteria, have their own dna, circular dna, divide in the same way, ribosomes are 70s (less than 20nm), have plasmids
85
what are the 6 stains when using light microscopes
methylene blue=turns nucleus blue
hematoxylin=turns nucleus purplish blue
eosin=cytoplasm pink
carmine=glycogen red
iodine=starch turns blue/black
tulylene red=turns nucleus red
86
what two stains used when using electron microscopes (tem)
heavy metal compounds such as osmium tetroxide and ruthenium tetroxide
87
what are nucleotides made of
carbon, hydrogen, oyxgen, nitrogen, phosphorus
phosphate group bonded with phosphodiester bond, monosaccharide sugar, nitrogenous bases - 4 types
88
what are the 5 bases of the nucleotides
adenine, guanine, uracil, cytosine, thymine
89
what are pryimidines
smaller bases, single carbon ring, thymine and cytosine
90
what are purines
larger bases, double ring structure, adenine and guanine
91
why are some dna distorted
only purine and pyrimidines can pair= if not, dna becomes distorted
92
dna v rna
rna has base uracil not thymine, dna double stranded rna single stranded, dna= pentose, rna=ribose, rna molecule shorter
93
what is the test for reducing sugars
place sample in boiling tube, add equal volume of benedict's, heat gently in water bath for 5 minutes, should react with copper ions and turn brick red if concentration of glucose is very high, if very low it should turn blue, then green, then yellow, than orange
94
what is the test for non reducing sugars
start with reducing sugarss experiments, if still blue, use the same substnace and heat with dilute hcl to hydrolyse it then repeat and compare observations
95
what is the iodine test for starch
add iodine to potassium iodide and sample, if it turns purple/black starch is present
96
colorimeter in reduicng sugars test
quantitative, add filter, calibrate using distilled water, do benedict's test, filter to remove precipitate, the more excess benedicts= less concentrated the substance, use to mesure transmission from absorbance and create calibration curve and compare results, add blank cuvette as a control
97
what are ions
atom with electrical charge, positive=cation, negative=anion,
98
what is an inorganic ion
does not contain carbon, play role in cellular processes and is the solution in the cytoplasm, low concentration which fluctuates, used in cell signalling and neuronal transmission, specific role depending on properties
99
what are co factors
chemical compounds required for protein to function, some inorganic ions are cofactors
100
what are the cations
hydrogen, sodium, potassium, calcium, iron and ammonium
101
what are the anions
nitrate, hydrogencarbonate, chloride, phosphate, hydroxide
102
what is the role of calcium
rigidity of bone teeth and cartilage , blood clot and muscle contraction through being released in sarcoplasmic reticulum when impulse reaches muscle fibre then binding to troponin which allows actin myosin to cross bridges, nerve transmission regulation, permeability of plasma membrane by regulating protein channels, cell wall development, activate enzymes needed for biological reactions
103
what is the role of sodium ions
osmotic pressure, control water levels and maintain ph, absorption of carbohydrates in intestines and water in the kidney, nerve transmission and muscle contraction, constituent of vacuole to keep turgidity, transport glucose and amino acids across plasma membranes, glucose and amino acids only enter with sodium in , actively transported out of epithelial cell, renters with amino acid and glucose,
104
what is the role of potassium ions
water levels and maintain ph, assist active transport, synthesis of glycogen and protein, breakdown glucose, generate healthy leaves, nerve transmission, muscle contraction, vacuole in plant for turgidity, reabsorption of water in kidneys, guards cells when opening stomata, voltage gated channel on axon membrane to allow diffusion potential difference returns to normal in repolarisation
105
what is the role of hydrogen ions
concentration determines ph, fluids in body are 7.4, essential for metabolic processes, change in ph affects enzyme structure, can cause denaturing, in photosynthesis and respiration, transport oxygen and carbon dioxide in the blood, regulate blood ph
106
what is the role of iron ions
two types, ferrous fe 2+ and ferric fe 3+, bind to oxygen as it is in haemoglobin the same with myoglobin but it has a polypeptide chain, transfer electrons in respiration and photosynthesis, in cytochrome for energy generation, switches between 2+ and 3+ to allow electrons to be donated or accepted
107
what is the role of ammonium ions
intermediate ion during deamination of proteins i. liver and kidneys, in amino acids, proteins, vitamins and chlorophyll, hormones, nucleic acid, maintain ph, in nitrogen cycle
108
what is the role of nitrate ions,
in soil, taken up by plants, source of nitrogen for protein synthesis, growth and repair, amino acids, vitamins and chlorophyll, proteins, nucleus acids, hormones , nitrogen cycle
109
what is the role of hydrogen carbonate ions
regulate blood ph, transports co2 in and out of blood
110
what is the role of phosphate ions
attached to form phosphate groups, in rna dna and atp, allow nucleotides to join and form polynucleotide, bonds in atp store energy, easily attached and deattached, when bonds are broken they release large amount of energy, for cellular processes, in phospholipids, bilayer of plasma membrane, in rigid bone teeth and cartilage, regulates blood ph, root growth in plants
111
what is the role of chloride ions
transport co2 in blood, move in and out of red blood cells to maintain balance, produce urine in kidney, maintain water balance, co2 in and out of blood, regulates affinity of hämoglobin in blood, used to produce hcl in stomach
112
what is the role of hydroxide ions
regulate blood ph, bond biochemical molecules, forms hydrogen bonds, dna base pairing, protein structures, water
113
what is the quantitative test of reducing sugars
red precipitate settles at bottom, the higher the concentration of the glucose the less blue the remaining benedict’s solution will be, intensity of precipitate also shows concentration compare with known substancess, same quantity and time and volume, take continuous samples to measure colour change,
114
what is the qualitative test of reducing sugars
using a colorimeter and filter, measure absorbable and transmission which gives a figure showing the glucose concentration due to wavelength of colours, absorbable measured in abituary units, calibrate using blank cuvette, create a graph curve
115
what are the two types of chromatography
tlc and paper
116
how does tlc chromatography work
add solvent to beaker, draw line in pencil on plate, place spots of compounds and some known compounds on baseline, place the plate into the beaker just above the solvent, substances will move up the plate, draw a solvent front on the furthest travelled,
stationary phase= metal sheet where molecules absorb, the more they interact the more they stick,
mobile phase= flows over stationary phase, polar or non polar liquid or gas, polar= water or alcohol non polar=alkene
117
how is chromatography used for separating amino acids,
same process as tlc but on chromatography paper, different times and distances depend on size and charge, polarity and solubility in of molecules, compare then spray with ninhydrin solution which reacts and forms blue violet colour
118
how is chromatography used to separate sugars
separates mixture of monosaccharides, have to be stained, place on pencil line of paper, add known monosaccharides to compare, suspend in solvent, travels and separates up paper, draw solvent front, compare and match which ones traveled the same distance
119
what is the synthesis of phosphodiester bonds
polynucleotides joined by condesation releasing a water molecule, occurs between phosphate group of one amino acid and pentose sugar of another which forms a phosphodiester bond, 1 phospjate 2 ester bonds, alternating chains results in sugar-phosphate backbone
120
what is the breakdown of phsophodiester bonds
hydrolysis of polynuclotides using water molecule, requires breakage of phosphodiester bonds
121
dna extraction process
freeze ethanol, cut onion and add washing up liquid, add to water bath at 60 for 15 mins, add detergent and heat, cool mixutre and stir, blend for 5 secs, filter using filter paper, pour into test tube, add ethanol and wait 3 mins
122
why do add detergent and heat in dna extraction
disrupt phospholipid bilayer, to release dna, denature enzymes
123
why do you cool and stir in dna extraction
evenly cooled, prevent dna breakdown
124
why do you use filter paper in dnma extraction
to remove cell debris and mebrane fragments,
125
why do you add protease in dna extraction
protease denatures and removes proteins
126
why do you add ethanol in dna extraction
nucleic acid is insoluble and dna precipitate is formed
127
nucleotide base pairing
complementary hydrogen base pairing, adenine with thymine creates two hydrogen bonds, cytosine and guanine creates 3 hydrogen bonds, purine + primindines
128
nucleotides condensation
condensation, covalent bonds and phosphodiester bonds, phosphate and pentose sugar, sugar phosphate backbone
129
structure of dna
double helix, antiparallel chains, double standed, two polynucleotide chains, complementary hydrogen base pairing, 5' end with phosphate group to 3' end with hydroxyl group= coding strand, sense strand
3' end to 5' end of carbons= template, anti sense strand, antiparallel
130
what does atp stand for
adenosine triphosphate
131
what is atp
energy carrying molecule, provides energy for cell processes, is a nucleic acid, phosphorylated nucleotide, made of nitrogenous base, three phospphate groups, supplies energy for anabolic processes, moving substances within and across cells, used in muscle contraction and nerve impulse transmission
132
what is adp
also a nucleotide like atp, but instead of three phosphate groups it has two
133
what is semi conservative replication
-dna helicase unwinds double helix by breaking down hydrogen bond between base and antiparallel strands
-free dna nucleotides attracted to the exposed bases on template strand with extra phsophates/activated nucleotides (whioch are joined by dna polymerase, catalyses condensation of deoxyribose sugar and phosphate group to form phosphodiester bond)
-hydrogen bonds between complementary strand form ladder of double helix
134
why is it important to keep one strand of dna during semi conservative replication
maximises accuracy from using existing template, genetic community ensured, as cells are replaced regularly
135
what causes genetic mutations
base inserted into comp. strand incorrectly, extra base inserted, base left out or random spontaenous mistakes
136
what is atp
adenosine triphosphate, energy carrying molecule, provides energy for cell processes, nucleic acid, phosphorylated nucleotide
137
what is adenosine triphosphate made up of
3 inorganic phosphate groups, 1 adenine (nitrogenous base) and ribose
138
what does atp do
supplies energy for anabolic reactions, moves substances across plasma membranes, , muscle contraction and merve impulse transmission, when bonds are broken, energy is released, recycled
139
how is atp formed
phosphorylation/condensation:atp synthesised from adp, atpsynthase catalyses, adp combines with pi (single inorganic phsophate)
140
how is atp broken down
hydrolysis, atp is broken down to adp, chemical energy released, atpase catalyses reaction, water is required
141
what is the difference between atp and adp and amp
amp=1 phosphate group
adp=2 phosphate groups
atp=3 phosphate groups
142
what are enzymes
biological catalysts made of gobular proteins, complex tertiary structure, active site specific and unique in shape, attaches to substrate in complementary shape, specific folding and binding, has two types, is anabolic or catabolic
143
what is anabolic
forms biological molecules
144
what is catabolic
breaks down biological molecules
145
what are the two types of enzymes
intracellular or extracellular
146
what is intracellular enzymes
made in the cell and actively function in the cell, e.g. catalase which breaksdown hydrogen peroxide to oxygen and water
147
what are extracellular enzymes
made in the cell but functions outside the cell e.g. amylase which is produced in the salivary glands and breaks down starch to simple sugars
148
what is semi conservative replication
one strand is conserved, a new one is also created, copying errors can lead to mutations, occurs in the s phase of interphase, it creates a lagging strand and leading strand
149
what is the process of dna replication
dna helicase breaks down hydrogen bonds between complmentary base pairs which unzips trands , the dna polymerase catalyses the condensation of phosphodiester bonds and on the lagging strand works back along the strand then dna is produced in okazaki fragments on the lagging strand only, dna ligase=catalyses the condesation of new nucleotides and rna primase synthesises the short rna to complementary dna template so dna polymerase can attach, and topoisomerase remove supercoiling at replication fork by introducing cuts, produces two identical strands
150
why is there a lagging strand and leading strand
the dna only moves in the 3' to 5' end but as dna is antiparallel one strand moves 5' to 3' end so it have to move back
151
what does dna helicase do
unwinds dna double helix, breaks hydrogen bonds of base pairs
152
what does dna polymerase iii do
synthesise new dna strands and places free nucleotides onto the strand
153
what does rna primase do
synthesise rna primers to start replication
154
what does dna polymerase i do
remove rna primers and fills gaps in strand
155
what does tropoisomerase do
prevents dna supercoiling
156
what does dna ligase do
join fragments of newly synthesised dna together to form continuous strands by forming phosphodiester bonds
157
what is evidence for semi conservative replication
by using nitrogen-15 isotopes and nitrogen-14 isotopes and modifying a bacteiras dna, the dna strands of 15 and14 will show what strandsare conversed in each generation, this can be shown in test tubes when centrifuged as nitrogen 15 is heavier meaning it is at the bottom of the test tube and nitrogen 14 and the top as it is the lighter dna strand, the mix would be intermediate and in the middle of the test tube
158
what are the two enzymes hypothesis'
lock and key and induced fit
159
what is the lock and key hypothesis
area in teriary structure that has a complementary shape to the active site, specific and fixed shape, precise due to complex tertiary structure
160
what is the induced fit model
enzyme and substrate interact and change shape slightly in conformational changes to maximise ability to catalyse reaction
161
what does catabolic reactions due to enzymes
strain on enzyme to break bonds by increasing pressure and releasing energy
162
what does anabolic reactions do to enzymes
reduces repulsion to make bonds by decreasing pressure and energy
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what is activation energy
amount of energy needed by substrate to become unstable enough for reaction to occur and products to be formed, destablisation of bonds make it more reactive enzyme provide low activation energy and alternative energy pathway
164
what is a gene
sequence of nucleotides that form a part of dna
165
what is the genetic code
a sequence of nucleotides code for production of specific polypeptides and proteins are made from a series of amino acids and the sequence determines the shape and behaviour of proteins (tertiary structure), and genes then control the protein shape and structure
166
what is the triplet code
determines
sequence of dna nucleotides as 3 bases form 1 amino acid, 20 different amino acids, some code for start and stop signals and let dna be read correctly and produce the correct sequence of amino acids making them non overlapping and degenerate as many codons code for the same amino acids which makes them universal and limit mutations
167
what is the function of mrna in genetic code
mrna is used as a template for [protein synthesis in the ribosome and each triplet forms a codon whereas trna have anticodonss which are complementary to codons
168
what is genetic code
it is degenerate, non-overlapping and unambigous and universal
169
what is degenerate
amino acid can be coded for by more than 1 codon
170
what is non-overlapping
each nucleotide only read as a part of one codon
171
what is unambigous
each codon only for 1 amino acid
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what is universal
some specific base triplets
173
how many codons and amino acids are there and why
64 codons, 20 amino acids and some amino acids code for the same codon, different combination, also have stop and start signals
174
how do genetic codes vary
different number of amino acids, different sequence of amino acids and different amino acids present
175
transcription
occurs in nucleus, mrna produced
-part of dna unwinds hydrogen bonds as complementary bases break
-exposed gene transcribed and complementary copy of code is made by mrna
-free rna nucleotides pair up by hydrogen bonds with complementary bases on template dna strand
-sugar phosphate group of rna nucleotide by phosphodiester bonds by rna polymerase to form sugar phosphate backbone
-gene transcribed so hydrogen bonds mrna and dna breaks and double strand reforms and mrna leaves via pores
176
translation
occurs in cytoplasm, mrna is translated and amino acid sequence is produced
-mrna attaches to ribosomes rrna
-free trna in cytoplasm have anti codons which attach to codons of mrna
-trna binds to specific amino acids and bring to mrna
-two trna fit to the ribosome at a time creating peptide bond
-catalysed condensation by trna sub unit of ribosome
-continues until stop signal is reached
-chain forms as final polypeptide
177
what is the role of rna polymerase in the process of transcription
adds free nucleotides to form sugar phosphate backbone and phosphodiester bond
178
what is denaturation
change in tertiary structure of proteins so they no longer function, bonds broken which stabilise tertiary structure that determines specific shape of active site
179
what is temperature co efficient Q10
a measure of how much the rate of reaction increases with a 10c rise in temp
180
enzyme action process
substrate is complementary to active site substrate fits into active site, induced fit, more esc, straining of bonds, products leave active site
181
denatured process
enzyme and substrate move continually and randomly due to ke, increase temp increase ke faster movement of molecules increase chance of collisions, more successful collisions more esc more products formed increases rate of reaction, rate of reaction increases with enzyme until it reaches optimum temperature, when it becomes higher than optimum the enzyme loses stability and is disrupted, increase temp increase movement of molecules molecules vibrate, break weak hydrogen and ionic bonds that stabilise tertiary structure disrupt specific shape of active site, enzyme is denatured
182
what is pH
measure of concentration of hydrogen ions, based on logarithmic scale of factor of 10, some enzymes work at a range of pHs some do not
183
effect of pH on enzyme
excess hydrogen ions interfere with hydrogen bonds and ionic forces that hold tertiary structure of protein that determines shape of active site and its charge as more protons cluster around the negative charge amino acid r griup in active site which interferes with binding of subtrate to active site
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how does pH affect the type of enzyme
extracellular=different from ph7, intracellular=around ph7
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what does a buffer do
resist change in ph by donating or accpeting hydrogen ions, occurs in blood plasma and is used in investigations
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examples of where pH affects location of enzymes
saliva-in the mouth, contains amylase which turns starch to maltose at pH 6-7
gastric juice-stomach, pepsin to turn protein to polypeptides at pH2
pancreatic juice-in small intestine, tyrpsin lipase amylase and maltose which turns protein to polypeptides, triglycerides to glycerol and fatty acids and starch to maltose at pH 8
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what is the effect of substrate concentraction on enzymes
increased number of substrate particles increase rate of collisions with active sites increasing esc and rate of reaction
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effect of enzyme concentraction on enzyme
increase number of available active sites in a articular area or volume increases esc and rate of reaction to Vmax/maximum, where all active sites are occupied by substrate particle, no more esc until products are released from the active site which can omly change Vmax by increasing temperature or enzymes, if concentraction of enzyme would increase active sites would increase towards Vmax then the substrate concentration becomes the limitng factor
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what are the types of inhibitors
competitive and non competitive
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what is a competitive inhibitor
similar shape to substrate so it competes with substrate to fit to active site and substrate cannot fit, depends on relative concentrations, reversible if concentration of substrate changes and rate of reaction increase
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what is non competitive inhibitors
binds to enzyme away from active site at allosteric site instead, changes active site shape so substrate can no longer bind, non reversible so and increase in concentration of substrate has no effect
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what is a non reversible inhibition
bind permanently to enzyme
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what is reversible inhibition
temporarily binds to enzyme
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what is the degree of reversible inhibition affected by
the strength of bonds between enzyme and inhibitors, strong covalent is irreversible and weak hydrogen and ionic are reversible
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what is end product inhibition
product of first reaction takes part in second reaction, each reaction is catalysed by different enzyme
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what are co factors
for example chloride ions, inorganic, for amylase, molecules or ions that dont directly participate and are not used up, help enzyme and substrate bind
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what are co enzymes
vitamins for example NAD acts as a hydrogen carrier (NADH) in reactions of respiration and is derived from vitamin B3, organic molecules and ions, participate in reaction so they are changed, carriers of chemcial groups between different enzymes, continually recycled
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what are prosthetic groups
zinc ions, co factor tightly bound to enzyme, contribute to 3d structure of enzyme
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what are precursors activators
inactive enzyme/apoenzyme + coenzyme (inorganic, co factor activator, tertiary structure and shape of active site changed) turn into activated enzymes/holoenzymes
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what is the plasma membrane structure
ampipathic-both phosphate group hydrophillic head and hydrophobic tail made of phospholipids, biayer as tails orientate towards fatty acids and head towards water, contians glycolipids, glycoproteins and proteins
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what are glycoproteins
molecules that comprise protein and carbohydrate chains that are involved in many physiological functions including immunity.enabling cell recognition of self and non-self cells. They also act as receptors for molecules such as hormones and drugs and pass on signals to intracellular components.
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what are glycolipids
made of proteins and carbohydrates maintain the stability of the cell membrane. Glycolipids are also important for cell recognition and connecting cells to form tissues. cell recognition, stability, antigens, receptor sites, signalling structural integrity, cell adhesion,
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what are the proteins in plasma membranes
intrinsic or extrinisic, pores channels or carriers made, transport, hydrophilic channels, allow polar substance in and out
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what is the fluid mosaic model
4 part model made in 1972, passive and active movement between cells and surroundings, cell to cell interations and cell signalling, phospholipids and proteins move around via diffusion, sideways within layers, different proteins interspersed through bilauer, scattered protein produced by proteins within phospholipid bilayer
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what is fluid
phospholipids within can move side to side while maintainiing integrity of plasma membrane as the proteins are free to move
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what is mosaic
phospholipid bilayer is dotted with proteins
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how does cholesterol affect the plasma membrane
increase fluiditiy in low temps due to decrease chance of repturing and less elbow room from being too tightly packed
decrease fluidity in high temps as phospholipids and proteins gain more ke, more gaps
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factors that affect the fluidity of plasma membrane
temperature, concentration of unsaturated or saturated fatty acids, relative proportions, presence of solvents and cholesterol
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what non polar molecules pass through plasma membrane
fats, lipids, oils,, cholesterol, oxygen, carbon dioxide, steroid hormones, fat and soluble vitamins
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8 functions of the cell membrane
not the plasma membrane, compartmentalistion (separates organelles from cytoplasm eg), used to form vesicles (bud off the GA, RER), control what substances enter/leave (glucose in mitocondria), surface for attatchment (mesosones and ribosomes on RER), intracellular communication (glycolipids and glycoproteins as receptors), isolation of chemical/metabolic pathways (lysosomes, hydrolytic enzymes), site of reactions (respiration in mitochondrial membrane), creation of concentration gradients (high conc of H+ in intermitochondrial membrane to matrix
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enzyme synthesis
depends on cell needs, genes for synthesising particular enzymes switched on or off
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enzyme degradation
continually degrading old enzymes molecules to their component amino acids
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diffusion definition
movement from high to low concentration, no net movement
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factors of diffusion
temperature, size of molecule, thickness of lining, concentration gradient, surface area
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what is the effect of concentration gradient on diffusion
difference in concentration of substance on two sides of the surface, randomly move across membrane, greater difference in number of molecules passing in 2 directions leads to faster ate
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effect of temp on diffusion
molecules have more kinetic energy, higher temperature, move faster, higher rate of diffusiom
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effect of size on diffusion
larger=diffuse slower, require more energy to move, uncharged/ non polar diffuse directly across phospholipid bilayer
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effect of surface area on diffusion
increase molecules crossing, faster rate, increased folding eg microvilli or cristae, surface area to volume ratio decreased, slower rate as distance required is too great
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facillitated diffusion
transport of polar molecules or ions in and out, carriers= changes shape for different molecules to diffuse,switch between two shapes by binding site open one side then other, relative conc, dependent for direction of movement, net diffusion of molecules in/out concentration gradient
channel proteins=forms pores in membrane for large charged particles for example sodium, potassium, diiffus, water filled pores, gated inside surface can move , control of exchange ions
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what are serial dilutions
series of dilutions of stock solution, concentration decreases same quantity between each test tube, ten fold or twofold, visual,calibration, standard curve, colorimeter
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what effects the permability of a cell membrane
temperature, ph and solvent concentration
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how does temperature effect permability
proteins denature, increase permability, substances escape, makes lipids mpre fluid and reduces effectiveness of cell membrane as barrier to polar membranes diffusion at higher speed due to increase in ke, reversible, around 40c proteins denature, disrupts memrbane structure, not effective barrier, irreversible, below 0=phospholipids cannot move, channel proteins denature, ice crystals pierce membrane
between 0 and 45=partially permeable
45+= phospholipid bilayyer more fluid, more ke, melt, more gaps, more permebale, water expands and pressure increases, protein denatures
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effect of ph on permability
affects tertiary structure of proteins, denature
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effect of solvents on permability
dissolves lipids in membrane, increases permability as it increases, organic solvents dissolve lipids
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what is osmosis
net movement of water molecules down a concetration gradient, from high water potential/low solute potential/ negative area to a low water potential/high solute potential/positive area across a partially permeable membrane
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what is water potential
potential energy of water molecules and the tendency to move, measured in kilopascals, pure water= 0 kPa, the rest are negative
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what is hypertonic in animal cells
solution of low water potential than cell, water leaves and shrinks cell, crenation
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what is hypotonic in animal cells
pure water or dilution has high water potential, water enters, cell bursts by cytolysis
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what is isotonic in cells
solution outside has the same water potential as inside, no net movement
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potato osmosis practical
equal sized potato cylinders for each solution, same mass, initial mass recorded, place in solution and water bath at set time and temp, dry and record final mass and calculate percentage change , if positive=gained water, high water potential, hydrostatic pressure, negative=loss of water, low water potential, plasmolysed
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onion osmosis practical
plasmolysis, lower water potential, leave by osmosis, protoplast shrinks, range of molarities of solution, gradually decreasing water potential, use epidermal strips, view under light microscope
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effect of water on animal cells
purewater/hypotonic solution outside=swell/burst, haemolysed (in RBC) /plasmolysis
concentrated/hypertonic solution outside=shrink/swell, cytolysed
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effect of water on plant cell
pure water/hypotonic=turgid, do not burst due to cell wall
concentrated/hypertonic-plasmolysed/flaccid
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osmosis example in paramecium and amoeba
-live in freshwater, animal cell,s cytoplasm has greater solute potential than outside the cell/surroundings, absorbs by osmosis, excess water collected by contractile vacoule, swells osmoregulatory organelles, then ejects
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how to calculate positive percentage change
final-initial divided by inital x 100
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how to calculate negative percentage change
initial-final divided by initial x 100
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what is active transport
movement of substances against a concentration gradient from low to high concentration using energy and transport proteins
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what are transport proteins
carrier proteins- which branch out to cotransporters
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types of co transporters
symporters and antiporters
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what are carrier proteins
attatches to carrier protein, changes protein shape, move across membrane with energy
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what are co transporters
type of carrier protein, bind to two molecules at a time- twp types-symporters and antiporters
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what is a symporter
both substance move in the same direction, one could go down the other against for example
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what is an antiporter
both move in different/opposite directions
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an example of both primary and secondary transport in action
in the first protein on the PM, sodium ions moves out-3 and potassium ions move in-2 in order to keep the charge balanced (sodium-potassium pump), this requires energy as sodium moves from low concentration inside to high concentration outside
in the second protein, sodium is still moving from low to high however glucose is moving in against the concentration gradient whereas sodium is moving down
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what are the two types of active transport
primary-which requires energy
secondary-does not require energy but relies on primary transport
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what is endocytosis
large molecules that cannot be abosrbed by carrier proteins enter the cell using energy
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what is exocytosis
large molecules use energy to exit cell-eg done by vesicle where it fuses with PM and releases contents
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what are the stages of cell cycle
interphase, miotic phase-mitosis + cytokinesis, G0-cell leaves the cell cycle
within the miotic phase is prophase-early and late, metaphase, anaphase, telophase
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why do cells leave the cell cycle (G0)
differentiation leads them to become highly specialised and perform their function indefinitely in G0, damaged dna means it is unable to replicate/ becomes senescent, age means more senescent cells occur and quinscence means some cells rejoin G1 if they get the right signal
when nutrients and growth factors are limiting, cells enter G0 instead of continuing cell cycle, occurs after checkpoint 1
they may be genetically programmed
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what are the 3 events of interphase
G1- growth phase= proteins are produced, organelles are replicated
S-synthesis- dna is replicated
G2-growth phase= cells increase in size, energy stores are made, dna is checked for errors
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what happens in G1
checkpoint at end of G1 before S, if satisfied, it passes to dna replication, if not it enters resting state of G0
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what happens at G2
chekc for dna breaks or damage, end of G2 before miotic, if satisfies it passes to mitosis
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what is the spindle assembly check point
metaphase checkpoint, mitosis cannot proceed until passed
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what are the 3 checkpoints
at g1 and g2 and spindle assembly
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what occurs in early and late prophase
chromatin fibres of rna and dna coil and condense to chromosome, nucleolus disappears and nuclear membrane breaksdown, protein microtubules form spindle-shaped structures, lining poles of cell, two centrioles migrate to opposite poles in animals cells and some plant cells, spindle fibres attatch to centromeres, start to move chromosomes to centre of the cell, nuclear envelope disappears
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what happens at metaphase
chromosomes moved by spindle fibres to form metaphase plate at centre of cell
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what occurs at anaphase
centromeres holding pairs of chromatids in each chromosome divide, chromatids are separated, pulled to opposite poles by shortening spindle fibres, v shape due to being dragged by centromeres through cytosol
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what occurs at telophase
chromatids have reached poles- now chromosomes, 2 new sets of chromosomes assemble at each pole, nuclear envelope reforms around them, chromosomes uncoil and nucleolus is formed, cytokinesis begins
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what occurs in cytokinesis
division of cell into 2 separate cells, in animal cells= cleavage furrow forms, cytoskeleton pulls cell-surface membrane inwards until it can fuse around the middle,
in plant cells= cleavage furrow not possiblr due to plant cell walls, vesicles from ga assemble where metaphse plate was and fuse with cell surface membrane and new cell wall sections form along new membrane, if the division of the cell wall was before the splitting it would cause osmotic lysis
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what is meiosis
meiosis i-reudction division- homologous chromosones are separated into 2 haploid cells
meiosis ii-pairs of chromtids in each daughter cell spearate, form 2 more cells, 4 haploid daughter cells in total
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what happens in prophase 1 in meiosis
chromosomes condense, nuclear envelope disintergates, nucleolus disappears, spindle formation begins, difference include the chromsomes pair up into bivalents which air pair of homologous chromosomes, moving the chromosomes to bring them together which leads to the chromatids entangiling is crossing over which also occurs
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what happens in metaphase 1 in meiosis
bivalents assemble along metaphase plate, orientation along metaphase plate of each pair is random and independent (indepdent assortment), results in different combinations of alleles facing the poles-genetic variation
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what happens in anaphase 1 in meiosis
homologous chromosome are pulled to either pole, but chromatids stay joined together, sections of dna on sister chromatids beakn off and rejoin on chismata and exchnage dna creating recombinant chromatids, genetic variation due to different alleles of same gene, sister chromatids are no longer identical
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telophase 1 in meiosis
chromosomes assemble at each pole, nuclear membrane reforms, chromosomes uncoil, cytokinesis begins-diploid- haploid is complete
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what happens in prophase 2 in meiosis
chromosomes condense and become visible, nuclear envelope breaks down, spingle formation begins
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metaphase 2 in meiosis
differs from 1 due to individual chromosomes assemble along metaphase plate as in mitosis, due to crossing over, the chromatids are no longer identical more identical, more independetn assortment and genetic variation
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anaphase 2 in meiosis
chromatids of individual chromosomes are pulled to poles after centromere divides, as in mitosis
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telophase 2 in meiosis
chromatids assemble at poles, chromosomes uncooil and form chromatin, nuclear envelope reforms, nucleolus becomes visivle
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what happens in telophase 2 in meiosis
chromatids assemble at poles, chromosomes uncoil form chromatin, nuclear envelope reforms, nucleolus becomes visible, cytokinesis occurs and results in 4 daughter cells, haploid cells due to reduction division, genetically different, due to crossing over and independent assortment
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what is the adaptation of erythrocytes and their function
flattened biconcave, increase the sa:v ratio, transport oxygen around the body, no nuclei, increase space for haemoglobin, flexible to squeeze through narrow capillaries
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what is the adaptation of neutrophils and their function
in immune system multi lobed nucleus, easier to squeeze through small gaps to get to site of infections, granular cytoplasm has lysosomes with digestive enzymes to attack pathogens
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what is the adaptation of sperm and their function
male gametes, deliver genetic information to female gamete, have tail/flagellum for movement and mitochondria to supply energy to swim, head has digestive enzymes to digest protective layer around ovum and allow sperm to penetrate for fertilisation
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what is the adaptation of palisade cells and their function
in mesophyll, contain chloroplasts to absorb large amounts of light for photosynthesis, rectangular box shape to be closely packed in a continous layer, thin cell walls which increase rate of diffusion of co2, large vacoule to maintain turgor pressure, chloroplasts can move within cytoplasm in order to absorb more light
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what is the adaptation of root hair cells and their function
surface of roots near growing tips, have long extensions/root hairs which increase the sa of the cell, maximises uptake of water and minerals from the soil
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what is the adaptation of guard cells and their function
surface of leaves at stomata, necessary for co2 to enter plants for photosynthesis, lose water and become less swollen, as a result of osmotic forces, they change shape and stoma closes to prevent further water loss, cell wall thicker on one side so cell does not change shape symmetrically as its volume changes
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what is the adaptation of squamous epithelium and their function
flat appearance, very thin due to squat cells and being only one cell thick, short diffusion pathway, in lining of lungs for rapid diffusion of oxygen into blood
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what is the adaptation of cilliated epithelium and their function
cilia on one surface that moves in a rhythmic manner, it lines the trachea for example, mucus swept away from lungs, goblet cells present release mucus to trap nay unwanted particles in air, prevents bacteria from reaching the alveoli
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what is the adaptation of cartilage and their function
connective tissue in outer ear and nose and ends between bones, fibres of proteins elastin and collagen, firm and flexible composed of chrondrocyte cells, embedded in extracellular matrix, prevents ends of bones rubbing together and causing damage
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what is the adaptation of muscle and their function
contract in order to move bones, move different parts of body, different types for example skeletal muscle fibres which are muscles attached to bone and contrian myofibril which contain contractile proteins,
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what is the adaptation of epidermis and their function
single layer of closely packed cells covering surface of plants, waxy waterproof cuticle to reduce the loss of water, stomata formed by a pair of guard cells that can open and close co2 in and out, water vapour and oxygen in and out
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what is the adaptation of xylem and their function
vascular tissue that transports water and minerals through plants, vessel elements elongated dead cells, walls stregthened with a waterproof material called lignin which provide structural support
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what is the adaptation of pholem and their function
vascular tissue, transports organic nutrients eg sucrose from leaves and stems where it is made by photosynthesis, to all parts of the plant where it is needed, column of sieve tubes cells and separated by perforated walls called sieve plates
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what are organs
collection of tissues adapted to perform a particular function in an organism eg mammalian hear t and leaf
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what are organ systems and examples of them
large multicellular organisms which have coordinated organ systems-
digestive system-breaks down large insoluble to small soluble and absorbs nutrients to blood and retain water will removing undigested
cardiovascular system-moves blood around body to provide an effective transport system for substances
gaseous exchange-brings air into body, oxygemn extracted for respiration, co2 can be expelled
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what is differentiation
process of becoming specialised, all body cells share the same dna, involves expression of some genes
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what are stem cells
undifferentiated cells which have the ability to become any specialised cells
from meiosis/mitosis, can continuously divide again and again, source of new cells necessary for growth, repair of tissue and development, once specialised they lose the ability to divide and enter G0, activity is strictly controlled so if division is not fast enough it would not be efficiently replacing tissue, leading to ageing which can form mass of cells/tumour which could lead to cancer
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what is potency
ability of a cell to differentiate to specialised cells
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what are the 3 types of potency
totipotent-can differentiate to any cell, fertilised cell/zygote, 8-16 cells from first miotic divisions, produce a whole organism, differentiate extra embryonic tissue (amnion, umbilicus)
pluripotent-stem cells that can form all tissue types not whole organism, in early embryos and origin of different types of tissue within organisms
multipotent-only form a range of cells within a certain type of tissue, haemopoetic stem cells in bone marrow-give rise to various types of blood cells
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stem cells in the replacement of rbc and wbc
mammalian erythocytes essential for 02 transport, adapted to maximise oxygen carrying capacity, room for haemoglobin, lack of nucleus and organelles causes short lifespan, replaced constantly, bone marrow, neutrophils are essential to the immune system, live 6 hours, increase during infection
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sources of stem cells
adult stem cells/tissue- present throughout, bone marrow, multipotent, can be artificially induced to be pluripotent, from umbilical cord of new borns, plentiful supply, invasive surgery unneeded, body will not reject
embryonic-very early stage of embryo development and totipotent, 7 day mass of cells(blasocyst) forms which is pluripotent and remain until birth of foetus
meristem in plants-tip of roots and shoots(apical meristem), in xylem and phloem (vascular cambium), vascular tissue grows as plant grows, pluripotent nature continues throughout
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uses of stem cells
for heart disease, type 1 diabetes, parkinsons, alzheimers. mascular degeneration, birth defects, spinal injuries, used in burn treatment and drug trials, developmental biology, gene therapy
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ethics behind stem cells
controversies as some of the embryos were from left over fertility treatments, the uk passed a law saying it can be specifically created in labs, removal destroys embryo which can be seen as murder, religious objections and moral, life begins at contraception, hold back progress of studies, restricts usefulness, can cause mutations, induced pluripotent adult stem cells
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what is miotic index
ratio between the no. of cells in a population undergoing mitosis to the total number of cells in a population
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miotic index equation
no of cells with condensed chromosomes divided by number of total cells times 100
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how to calculate miotic index
count the number of cells in the field of view, count the number of cells in the field of view actively dividing and calculate using the euqation
