bio Flashcards
(289 cards)
1
Q
what are the monomers and what polymers do they make
A
amino acids ~> protein
monosaccharide ~> polysaccharide
nucleotides ~> nucleic acids
triglycerides
(3 fatty acids / glycerol) phospholipids
(glycerol / phosphate / 2 fatty acids )
are not polymers
2
Q
what do ammino acids consist of
A
carboxyl group
nh2
c in middle with 1 h and 1 r
3
Q
name of reaction that forms / breaks polymmers
A
condensation make water
hydrolysis break produce water
4
Q
disaccharides to their monomers
A
lactose = glucose+galactose
maltose =
glucose+glucose
sucrose =
glucose+fructose
5
Q
two different types of glucose
A
alpha glucose = oh on left and right both on bottom
beta glucose = oh on top on the right and on the left its on bottom
6
Q
polymerisation of alpha glucose in plants cells
A
- chains will coin into alpha helix and form starch
- they are insoluble so wont affect osmosis
- many branches so lots of area for amylase enzyme to break them down quickly for use in respiration
6
Q
types of bonds of the polymers
A
polysaccharide = glycosidic
ammino acid = peptide
nucleic acid =phosphodiester
triglyceride/ = ester
phosphodiester
7
Q
polymerisation of alpha glucose in animal cells
A
- polymers of glucose form short highly branched chains
- easily broken down by amylose so result in high amount of energy released easily
- insoluble so no affect on osmosis
8
Q
polymerisation of beta glucose
A
- form cellulose
- long straight unbranched chains that are parallel to each other these are cross linked to eachother
- makes the molecule strong and is used in the cell walls
9
Q
testing for reducing sugar
A
- grind sample in pestle and mortar
- put sample in water forming a solution
- 2 cm3 of sugar solution and benedicts
- leave in heated bath for 5 mins
- +ve result is brick red ppt form and -ve result is remain blue sol
10
Q
testing for non-reducing sugar
A
- grind sample in pestle and mortar and dissolve sample in distilled water filter out debris
- put sample in water forming a solution
- 2 cm3 of sugar solution and benedicts
- leave in heated bath for 5 mins
- -ve result is remain blue sol
- 2cm3 of sugar solution and hydrochloric acid heat for 5 mins
- 2cm3 of sodium hydrognecarbonate
- now add benedicts should be a +ve result is brick red ppt form and -ve result is remain blue sol
11
Q
test for starch
A
add drops of iodine and if present blue black solution if not then brown orange solution
12
Q
test for lipids
A
- dissolve sample in ethanol
-add distilled water and shake more - if present then white emulsion
13
Q
what does
-saturated
-unsaturated
- polyunsaturated
A
-saturated only c-c bonds
-unsaturated some c-c and some c=c
- polyunsaturated many c=c and some c-c
14
Q
which part of triglyceride and phospholipid is hydrophobic and which is hydrophillic
A
triglyceride - whole thing is hydrophobic
phospholipid - head is hydrophillic and tails are hydrophobic
15
Q
test for protein
A
- grind and dissolve sample in distilled water filter out debris
- 2cm3 of sample solution and add 2cm3 of biuret reagent
- if +ve then solution turn purple and -ve remain blue
16
Q
protein hierarchy
A
1° = simple amino acid sequence / peptide chain
2° = alpha helix / beta pleated sheet hydrogen bonds form between layers
3° = more folding results formation of hydrogen, disulfide, ionic bonds between specific parts of protein molecule in
specific structure
4° = many other proteins come and bind to this one and form a large structure
17
Q
strengths of bonds in protein and factors that affect the strength of these
A
hydrogen - weak
disulfide - strong
ionic - strongest
pH change can weaken these strengths
18
Q
Using chromatography to separate a mixture of amino acids
A
- chromatography used to separate a mixture of amino acids
- A spot of the unknown mixture is placed on a line at the bottom of the chromatography paper
- Spots of known standard solutions of different amino acids are then placed on the line beside the unknown sample spot
- paper is then suspended in a solvent
- Each amino acid will be more or less soluble in the mobile phase
The unknown amino acid can then be identified by comparing and matching them with the chromatograms of the known standard solutions of different amino acids
19
Q
define what an enzyme is
A
an enzyme is a biological catalyst that lowers activation energy for specific reactions
and only create enzyme substrate complexes for specific substrates complementary to the tertiary structure
20
Q
descirbe the mechanism for enzymes
A
induced fit model
shape of active site changes its tertiary structure slightly to better accomodate the substrate
this then catalyses the reaction and the products are released
21
Q
factors effects the rate of enzyme-controlled reactions
A
enzyme concentration
substrate concentration
concentration of competitive and of non-competitive inhibitors
pH - changes bonds in tertiary structure affects the overall shape denaturing the molecule decrease rate
temperature - changes bonds in tertiary structure affects the overall shape denaturing the molecule decrease rate
22
Q
state both types of inhititors and how they affect rate of reaction with enzymes
A
competitive inhibitor - similar shape to substrate occupying the active site stopping formation of enzyme substrate complexes may drop off to allow substrate to bind
noncompetitive inhinitors - bind to allosteric site this isnt the active site bot will change the shape of the active site preventing formation of enzyme substrate complex
23
Q
types of nucleotides and their bases
A
dna - adenine guanine cytocine thymine
rna - uracil adenine cytocine guanine
24
describe process of dna replication
semiconservative replication
1) dna helicase unwinds hydrogen bonds between complementary bases pairs creating two single strands of dna
2) free nucleotides will bind to the open bases on the nucleotide template strands
3) dna polymeraise will form phosphodiester bonds forming the sugar phosphate back bone
4) leads to two identical dna strands being formed
25
messelson and stahl
25
structure of atp molecule
adenine base ribose sugar and 3 phosphate groups
26
where is atp used in organism
- active transport
- movement/ muscle contraction
- metabolism
26
what enzyme catalyses the hydrolysis of atp and what is formed
atp hydrolase
ATP ~> ADP + Pi
breaking of the unstable bond between phosphate 2-3 releases energy
27
how is atp formed
ATP is resynthesised by the condensation of ADP + Pi .
This reaction is catalysed by ATP synthase during photosynthesis, or during respiration.
28
properties of water
- metabolite
used in many metabolic reactions, including condensation and hydrolysis reactions
- solvent
in which metabolic reactions occur
- relatively high heat capacity,
buffering changes in temperature
- relatively large latent heat of vaporisation, providing a cooling effect with little loss of water through evaporation
- 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.
29
key struct and function of nucleus
nuclear pores , nuclear envelope , chromasomes
nucleolus (site of rna production)
site of dna replication and transcription
stores genetic info
30
key struct and function of rough endoplasmic reticulum
folded membranes called cristae
protein synthesis
31
key struct and function of
smooth endoplasmic reticulum
folded membranes called cristae
synthesise lipids and carbohydrates
32
key struct and function of
golgi apparatus / vesicle
folded membranes called cristernae and vesicles surrounding
add carbohydrates to proteins to form glycoproteins
transport / modify lipids
33
key struct and function of
lysosomes
contain enzymes
exocytosis
phagocytosis
34
key struct and function of
mitocondria
folded membrane called cristae and inner fluid called matrix
site of aerobic respiration
35
key struct and function of
ribosome
site of protein synthesis
36
key struct and function of
vacuole
filled with fluid surrounded by tonioplast membrane
make cell turigid provide support
temporary store of starch and amino acids
37
key struct and function of
chloroplast
double membrane
contain thylakoid and many of these make granum thes econtain chlorophyll
fluid surrounding these is called stroma
site of photosynthesis
38
key struct and function of
cell wall
plants - cellulose
fungi - chitin
prokaryotic - meurin
provide structure and strength
39
differences between eukaryotic and prokaryotic cell
- prokaryotic are much smaller
- prokaryotic have no membrane bound organelles
- prokaryotic have no nucleus
- prokaryotic smaller ribosome
40
structure of virus
why they may be described as acellular
-capsid
- attachment protein
- viral genetic code
- reverse transcriptase
acellular = no surface membrane
41
viral replication
1. Attachment proteins attach to receptors;
2. Viral RNA (nucleic acid) enters cell;
3. Reverse transcriptase makes DNA from RNA;
4. The DNA is translated (produces) into viral proteins, capsid & enzymes
5. Virus assembled and released from cell
42
define magnification
how many times larger the image is in comparison to the origional object
43
define resolution
minimum distance between two object where they can still be seen as two seperate objects
44
limitations of optical microscopes
- Light has a longer wavelength
- lower resolution
- Lower magnification
45
limitations of transmission electron microscopes
- samples are in a vacuum
so cant examine living cells
- More complex & time consuming specimen preparation procedure.
may damage the specimen producing artefacts
- Black & white image
46
limitations of scanning electron microscopes
- samples are in a vacuum
so cant examine living cells
- More complex & time consuming specimen preparation procedure.
may damage the specimen producing artefacts
- Black & white image
47
advantages of using optical microscopes
- view live specimens
- Coloured images
- Preparation rarely damage the specimens
48
advantages of using scanning electron microscope
- Electron wavelength is shorter so higher resolution than optical
- can study more detail than optical
- Study 3D structures.
- Higher magnification than optical
49
advantages of using transmission electron microscope
- Electron wavelength is shorter
- highest resolution
- Study detailed organelles
- Highest magnification
50
conversion from micrometer ( µm ) to milimeter (mm)
µm / 1000 = mm
mm * 1000 = µm
51
describe process of cell fractionation
1) cells need to be put into an ice cold isotonic buffer solution
2) solution put in blender to break open cells
3) filter to remove large debris
52
magnification eq
m = i / a
53
why is sample placed into special solution for cell fractionation state the conditions and reasoning
isotonic - prevent movement of water into cells causing lysis
ice cold - prevent destructive enzyme activity
buffer solution - prevent proteins denaturing
54
explain the process of ultra centrifugation
1) after cell fractionation supernatant put in counter balalnced centrifuge and spun at slow speed for short period of time
2) the most dense organles will settle at the bottom and form a pellet filter this out and respin the supernatant at higher speed for longer duration
3) repeat until you have desired thing
55
describe process of mitosis
1) inter phase
organelles double and dna replicates
2) prophase
chromasomes condense and become visable nucleolus disolve
3) metaphase
chromasomes align in middle of the cell and spindle fibres attach to centromeres on the chromatids
4) anaphase
spindle fibers retract and pull on centromere causing it to split in half
5) telophase
chromasomes uncondense spindle fibres dissapear nucleus reform cytoplasm split via cytokeneisis
56
eq for mitotic index
num cells under go mitosis
------------------------------------
tot num of cells
ans * 100
57
describe process of binary fission
1) replication of the circular DNA and of plasmids
2) division of the cytoplasm to produce two daughter cells
3) each with a single copy of the circular DNA and a variable number of copies of plasmids.
58
why dont virus under go replication
as they are nonliving cells
59
whats the structure of the cell membrane
the phospholipid bilayer consists of hydrophillic phosphate groups and hydrophobic fatty acid tails
60
whats cholesterol and how does it affect movement into cells
Cholesterol may also be present in cell membranes where it restricts the movement of other molecules making up the membrane
61
what are channel proteins
they are the tunnels that allow larger molecules through the membrane
62
what are carrier proteins
the are proteins that once binded to they take the molecule to the other side
63
whats simple diffusion
- Diffuse down a diffusion concentration gradient
- high to low concentration
through phospholipid bilayer
- Passive
64
whats facillitated diffusion
- Substances diffuse through channel proteins, down a diffusion gradient
- high to low concentration
- Passive
- Specific shape channel/carrier protein determines which substances can diffuse through
65
whats active transport
- Ion binds to a specific carrier protein with a complementary tertiary shape
- Ion moves against the concentration gradient
low to high concentration
- Using ATP from respiration
- ATP used to change the protein shape, releasing the ion on the other side
66
whats osmosis
- diffusion of water
from a higher to a lower water potential (Ψ) (down a water potential (Ψ) gradient
- across a partially permeable membrane
- passive
67
whats cotransport
- Energy from ATP actively transports sodium ions out of the cell into the blood
- creating a sodium ion diffusion gradient from the lumen, into the cell
- A glucose molecule is co-transported with sodium ions, using the same carrier protein into the cell
- Glucose diffuses out of the cell into the blood by facilitated diffusion
68
how cells are adapted for rapid transport of substances
- increased surface area
- increased num of channel/ carrier proteins
69
how do lymphocytes distinguish between slef/ non-self cells
each cell has specific molecules on its surface w specific shapes these can be used to identify it
70
how are antigens used in immune response
they are located on surface of pathogen and trigger response from lymphocyte
71
describe process of antigenic variability
mutation occur in specific gene responsible for the antigen
any previous immunity to pathogen will be lost
72
describe the barriers blocking pathogens entering the body
skin is a physical barrier that blocks pathogens
stomach acid is a chemical barrier blocking pathogens
white blood cells are the next defence
73
state non specific immune response
non-specific = phagocytosis
- agglutination of atigens as sntibodues stick them togeather in clumps
- The phagocyte is attracted to the pathogen by non-self ANTIGEN.
- The pathogen is ENGULFED and enclosed in a PHAGOSOME (vesicle).
- LYSOSOMES (made by Golgi) (contain
lysozyme enzymes) fuse with the phagosome.
- Lysozymes enzymes hydrolyse molecules and break down the pathogen
(then exocytosis of products)
74
state the specific immune response
specific = t lymphocyte
the t cells originate i the thymus thats where the t comes from
1) Pathogen enters the body.
2. Phagocyte cells engulf and destroy pathogen and present pathogen’s antigen on their surface.
3. Antigens have a specific tertiary structure. T-cells with a complementary receptor bind. Cytotoxic T cells, kill infected body cells.
4. Helper T-cells stimulate B-cells.
5. B-cells undergo mitosis to clone & make plasma cells.
6. Plasma B cells produce (monoclonal) antibodies.
7. B cells divide (by mitosis) to form Memory B-cells & T-cells divide to form Memory T-cells.
8. More antibodies are produced faster in the secondary immune response. also known as ACTIVE immunity
75
describe structure of antibody
- Y-shaped
- 2 long polypeptide chains - 2 short polypeptide chains
- constant region
- variable region / antigen-binding site at ends
76
whats passive immunity
antibodies put into organism
no long term immunity
breast milk
77
whats active immunity
antibodies created in response to non self antigens
78
define vaccine
a dead or inactive form of the pathogen that gets injected into the body
79
describe what happens after vaccine injection
- exposure to antigen activate b cell to differentiate
- b cell undergo mitosis and make large numbers of cells these then differentiate into plasma cells or memory cells
- plasma cells make antibodies
- memory b cells divide rapidly into plasma cells when reinfected by same pathogen these make lots of antibodies rapidly
80
what is herd immunity
81
structure of HIV molecule
attachment proteins = on the outside of the molecule
lipid envelope = hold all the stuff
capsid = hold the rna and the reverse transcriptase
82
describe process of viral replication
1. Attachment proteins attach to receptors;
2. Viral RNA enters cell;
3. Reverse transcriptase makes DNA from RNA;
4. The DNA is translated (produces) into viral proteins, capsid & enzymes
5. Virus assembled and released from cell
83
how does hiv result in symptoms of aids
virus replicate in the helper t cell this interferes w normal function of immune system
84
two use of monoclonal antibodies
- targeting medication to specific cell types by attaching a therapeutic drug to an antibody
- medical diagnosis.
85
describe how we can prevent uncontrolled cell growth of pathogen by the use of antibody.
- monoclonal antibodies binding site complementary to that of an antigen on the outside of the cancer cell
- these attach to cancer cell and prevent chemicals binding that enable the uncontrolled cell division
- these dont damage any other healthy cells only the
86
describe how we can target medication to specific cells by the use of antibody.
- monoclonal antibody created that has binding site complementary to that of an antigen on the outside of the cancer cell these are also attcahed to drugs
- cancer drugs are delivered straight to the cell and are killed this is good as it means that there are lesss negative implications when compared to treatments such as chemotherapy and radiotherapy
87
uses of antibodies for medical diagnosis.
monoclonala ntibodies could be used to diagnose pregnancy, cancer, covid
88
describe process of ELIZA testing
1) add antigens to a well and wash multiple times remove any unstuck antigens
2) add complementary antibody forming antigen-antibody complexes wash removing any unbinded antibody molecules
3) Add a second antibody, with an enzyme attached.
and wash
5) Add a colourless substrate which is complementary to & binds to the enzyme’s active site if present. and produce coloured product
89
calc sa : v
surface area / volume
90
how is the sa : v advantageous for exchange in organisms
the larger the sa : v is the more efficient the transport
91
adaptations for increased sa : v in humans
villi and micro villi- maximise absorbtion of food
alevoli and bronchi - maximise gas exchange
92
adaptations for increased sa : v in terrestrial insects
spiracles and tracheoles -
maximise gas exchange
93
adaptations for increased sa : v in fish
gill fillaments and lamellae- maximise gas exchange in fish
94
adaptations for increased sa : v in plants
thin wide leaves -maximise gas exchange in plants
95
define breathing
movement of air in and out the lungs
96
define respiration
the chemical reaction happening in the mitocondria releasing energy in the form of atp
97
human gas exchange system breathing in
1) diaphram contract and flatten
2) external intercostal muscles contract and ribs move up and out down pressure gradient
3) volume of thoraxic cavity increases pressure decreases
4) air flows in via trachea down to bronchi then bronchioles and finally to the alveoli where it diffuses into cappillary
98
human gas exchange system breathing out
1) diaphram relax and enlarges
2) internal intercostal muscles contract and ribs move down and in
3) volume of thoraxic cavity decreases pressure increases air goes down pressure gradient
4) air flows out via alveoli then bronchioles and then bronchi and finally trachea where its breathed out
99
define pulmonary ventialtion and how is it calculated
total volume of air moving into the lungs in one minute
pul vent = tidal vol * vent rate
100
how humans have developed short diffusion pathway to aid exchange of substance
avleolar epithelium is one cell thick and
101
how humans have developed to maintain diffusion gradient to aid exchange of substance
the alveoli are wrapped in capillaries and these are constantly taking away the oxygenated blood and bringing deoxygenated blood
102
how have insects evolved to prevent water loss
water proof exoskeleton
103
gas exchange in insects
air flows in through the spiracles to the trachea these branch off to tracheoles these go deeper into the the tissues in the insect and provide oxygen to all of the respiring cells
104
methods of gas exchange in insects
1) gasses may diffuse in and out
2) muscles in abdomen contract move gasses in and out
3) when in flight muscle cells respire anaerobically this produces lactate lowering water potential of the muscle cells pulls water into the cells form tracheoles via osmosis decrease volume in tracheole resulting in more air being drawn in
105
how insects have developed short diffusion pathway to aid exchange of substance
walls of tracheoles are thin
106
how insects have developed to maintain diffusion gradient to aid exchange of substance
use of oxygen and production of co2 result in steep diff grad
107
how fish have developed to maintain diffusion gradient to aid exchange of substance
counter current flow water flows in opposite direction to blood flow this maximises amount of oxygen intake
108
structure of **dicotyledonus** plants
plaisade mesophyll - site of photosynthesis
mesophyll - air spaces
stomata - where gas is taken up
109
how plants have adapted to reduce water loss
stomata close at night to reduce water loss by evaporation
110
adaptations of xerophytes
to reduce water loss
curled leaves -
sunken stomata -
small hairs sticking out of plant
thick waxy cuticle
deep / wide spread root system
111
define digestion
large biological molecules are hydrolysed into smaller molecules that can be absorbed across cell membrane
112
digestion of carrbohydrates
amylase from pancreas and salivary gland hydrolyse polysaccharide into many disaccharides breaking glycosidic bond
sucrase / lactase are membrane bound enzymes that hydrolyse lactase and sucrase into monosaccharides
113
digestion of proteins
1) endopeptideases - hydrolyse peptide bond in middle of ammino acid chain
2) exopeptidase - hydrolyse peptide bond at end of ammiino acid chain
3)membrane bound dipeptideases - hydrolyse peptide bonds between dipeptides
114
digestion of triglycerides
1) bile salts emulsify lipids into smaller droplets
2) lipase breaks ester bonds in triglyceride and form fatty acids + glycerol
3) micelles formed consist of fatty acids and glycerol and these are taken to the lining of the illeum
115
lipid absorbtion
1) micelles consisting of fatty acids and glycerol are taken to the lining of the illeum
2) fatty acids are non polar so diffuse through phospholipid bilayer leave behind micelle
3) move to smooth endoplasmic reticulum and are made back into triglyceriides
4) moves to golgi and gets a protein added to it forms a chlomicron
5) chylomicronleave via exocytosis and move to the lymph system and they are then transported around the body
116
what are haemaglobin and how do they benefit the transport of oxygen
specific tertiary structure allows for 4 oxygen molecules to bind
cooperative binding
117
explain how oxygen is loaded onto haemaglobin
oxygen is loaded in high partial pressure of oxygen and then unloaded in area of low partial pressure
shown on oxyhaemaglobin dissociation curve
118
whats the bohr effect
high co2 conc causes affinity for oxygen to decrease as the acidic nature of the high co2 environment causes the tertiary protein structure to change slightly
119
why do different organisms have diff types of haemaglobin
to cope with the demand of their environment
120
define double circulatory system
travels through the heart twice in one full circuit
body > heart > lungs > heart > body
121
why does blood flow through lungs at lower pressure
- prevent damage to the alveoli
- blood flow slower speed more time for gas exchange
122
state blood pathway as it enter the heart from body
deoxygenated blood travel into heart via vena cava to the right atrium through atrioventricular valve to the right ventricle through semi lunar valve to pulmonary artery to lungs gets oxygenated comes back into heart via pulmonary artery to the left atrium down through atrioventricular valve to left ventricle through the semi lunar valve to aorta to the rest of body
123
what blood vessel carries blood to and from the kindey
renal artery renal vein
124
what blood vessel carries blood to the heart muscle
what happens if a block occurs here
coronary artery
cardiac arrest heart muscle doesnt have the correct bloodflow
125
two features of the cardiac muscle that are advantageous
myogenic - contract / relax without hormonal stimulation
never fatigues as long as there is a constant supply of oxygen
126
whats the function of valves in the heart
when do they open
- prevent backflow of blood
- maintain unidirectional flow blood
only open when pressure before it exceed pressure after it
127
structure of arteies and how this affects its function
thick muscular cell wall
- constrict and dilate to control blood flow
thick elastic tissue in walls
- maintain the blood pressure stretch and recoil
thick muscle tissue
- prevent vessel from bursting facillitate high pressure
128
structure of veins and how this affects its function
relitively thiin
- no control of the blood flow only carry blood in low pressure
valves
- prevent backflow and unidirectional blood flow
129
structure of capillaries and how this affects its function
many branches
- inc sa:v
one cell thick
- short diff pathway
small lumen
- only one cell goes through at a time maximise diffusion
130
structure of the arteriole
muscle layer
- thicker than artery as constricting the lumen results in reduced blood flow into capillaries
elastic layer
- thinner as the blood pressure is lower than artery
131
cardiac output calculation
heart rate * stroke vol
132
define stoke vol
amount of blood that leaves the heart each beat
133
formation of tissue fluid
1) capillaries have small gaps called fenestrations
2) as blood enter capilaries from arterioles results in high hydrostatic pressure of the blood
3) water and small molecules are forced out to surroundiing cells this is called ultrafiltration
4) towards venous end hydrostatic pressure has decreased as so much has been forced out pressure within capillary has dropped the water potential has also dropped
5) liquid then re-enter capillary via osmosis
134
how does water move out of plant cells
transpiration is the loss of water through the stomata
135
what 4 factors affect transpiration and how do they affect it
light
- the more light the more stomata that are open so more water loss
temperature
- hotter water molecules have more kenetic energy move faster / evaporate faster
humidity
- water potential outside of leaf is greater than inside this results in less evaporation
wind
- maintains the water potential gradient
136
key points that aid the water moving into root and up plant
cohesion tension theory
- cohesion between water molecules / hydrogen bonds makes them stick togeather create contious water column
-adhesion water molecule stick to walls of xylem thinner the xylem the greater the capillary effect
- root pressure as more water move into root the and therefor increase the pressure within the root forces water up the root
137
process of water moving up plant
1) water evaporate out stomata loss in volume create lower pressure (transpiration)
2) as water is lost more water is pulled up xylem to replace it
3) due to hydrogen bond the water creates continous column via cohesion
4) water molecules stick to walls of xylem via adhesion this further helps the movement of water up the plant
138
whats the process of movement of minerals and organic matter through the plant
translocation
139
describe the mass flow hypothesis
consist of source
( photosynthesisng cell)
sink ( respiring cell )
1) sucrose made by source cells active transport to the sieve tube element via the companion cell
2) water will move into the sieve tube elements from the xylem as there is a high water potential gradient and then out of the sink cell as this creates water from respiration
3) the sucrose will be carried down the hydrostatic pressure gradient to the sink cell
4) sucrose actively transported into the sink cell via the companion cell this decreases the water potential
5) water move from the sieve tube elements back to the xylem via osmosis
140
investigating translocation
Tracing
- only provide plants with radioactively labeled carbons
- this will be used in photosynthesis to produce sugars
- thin slices of stem placed onto xray film
- this highlights where mass is moving phloem
141
key characteristics of prokaryotic dna
-DNA molecules are short
- circular
- not associated with histone proteins
- dont contain introns
142
key characteristics of eukaryotic dna
-DNA molecules are long
- linear
- associated with histone proteins
- contain introns
143
define gene
base sequence that may encode for
- amino acid sequence in polypeptide
- functional RNA
144
define locus
exact position of a particular gene occupies on a chromosome
145
three features of genetic code that act as an advantage
- degenerate = different sequences code for same thing
- universal = one sequence codes for same thing in all organisms
- non overlapping = base sequences only belong to one triplet dont get shared around
146
what are exons and introns
exons = useful triplets that code for something
intron = not useful triplet dont code for anything
147
define genome
complete set of genes in a cell of an organism
148
define proteome
a full range of proteins that a cell is able to make
149
key features of tRNA
transfer RNA
clover leaf shaped
complementary anticodon
amino acid binding site
150
first stage of protein synthesis
- transcription
- DNA helicase attaches at start triplet
- DNA helicase moves along DNA unwinding it and breaking hydrogen bonds
- One DNA strand acts as a template
- RNA nucleotides align with template DNA strand by complementary base pairing.
- RNA polymerase joining adjacent RNA nucleotides with phosphodiester bonds, forming the sugar-phosphate backbone (condensation reaction)
- RNA polymerase meets stop triplet on DNA & falls off from DNA
- DNA rewinds, Hydrogen bonds reform
pre-mRNA is spliced to remove introns, leaving exons forming mRNA. This leaves via a nuclear pore and enters the cytoplasm.
151
second stage of protein synthesis
- translation In the cytoplasm
- The start codon of the mRNA enters the ribosome
- The tRNA anticodon binds to complementary mRNA codons
- The tRNA has a specific amino acid attached, which is complementary to the tRNA anticodon
- The amino acid joins by a peptide bond a condensation reaction to an adjacent amino acid, using ATP from respiration.
- The tRNA is released and leaves the ribosome.
Ribosome moves to the next codon and along the mRNA to form the polypeptide, until it reaches the stop codon.
152
define gene mutation
random change in dna base sequence
153
factors increasing chance of dna mutation
exposure to mutagenic agents will increase chance of mutation
high energy radiation
ionising radiation
harmful chemicals
154
types of gene mutation and what is the affect of this
addition - base is added onto the sequence and result in frame shift
deletion - base is removed in sequence and result in frame shift
sustitution - base is swapped out for other base doesnt result in frame shift
154
mutation in chromasome
occurs randomly in mieosis and results in non-disjunction this is when chromasomes dont equally split and result in different num of chromasomes
155
variations in meiosis
- independant segregation
chromasomes line up opposite on the equator and is completely random which 2/16 get pulled to the side
these two then further seperate to just one of each pair in the daughter cell
- crossing over
homolygous pairs line up and twist around eachother and break off result in new combination of allele
156
define genetic diversity
number of different alleles of all genes in a population
157
process of natural selection
1) phenotypic variation
new alleles result from random mutation variety of alleles in the gene pool
2) selection pressure
Competition for light, Disease or Predation
3) those with advantageous alleles are better adapted to the environmental conditions
4) those with advantageous allele outcompete those with disadvantageous alleles, so survive and reproduce therefor passing on the new alleles to the next generation
5) Within the gene pool advantageous alleles increase in frequency
This may lead to SPECIATION
158
types of selection
1) directional selection
where extreme advantageous allele is selected for
2) stabilising selection
extreme alleles selected against and the average alleles selected for
3) disruptive selection
both extreme alleles selected for result in speciation
159
define species
two organisms that are able to interbreed and produce fertile offspring
160
whats courtship and how are courtship behaviours advantageous
a sequence of behaviours that are specific to certain species
- help identify opposite sex
- help identify potential mate
- increased mating success
161
whats the binomial naming system and how is it used
methods of universally identifying the organism
genus species
161
what is the sequence of classification
do domain
kinky kingdom
pants phylum
come class
off order
for family
gay genus
sex species
162
define species richness
number of species in a community
163
define index of diversity
An index of diversity describes the relationship between the number of species in a community and the number of individuals in each species.
Calculation of an index of diversity ( d ) from the formula
d=N(N-1)
---------
Σn(n-1)
N = total number of organisms of all species
n = total number of organisms of each species.
164
methods of investigating diversity
1) frequency of measurable or observable characteristics
2) the base sequence of DNA
3)the base sequence of mRNA
4)the amino acid sequence of the proteins encoded by DNA and mRNA.
164
3 key properties of ATP
1) very unstable bonds between the 2nd and 3rd Pi are easily broken immediately releasing energy, in a single reaction
2) ATP is Easily reformed
easy to reform bond between the 2nd and 3rd Pi
3. ATP is Soluble which means.. ATP is dissolved in the cell, so readily available for biochemical processes e.g. DNA replication
165
Farming techniques reduce biodiversity.
1) planting more hedges
Advantages
- Increase biodiversity
- increase in predators of pests so less crop damage - higher yield/income
Increase in pollinators so more yield/income
Disadvantages
- Reduced land area for crop growth/income
- More difficult to farm so less income
2) land clearance for agriculture
Advantages
- Increased yield of food crops.
- Cheaper grazing for cattle and hence cheaper food.
Disadvantage
- Loss of habitat so predator of crop population may increase & more pesticides needed
- Reduced habitat so species diversity reduced
Increased fertilizer use
166
stages of light dependant reaction
1) Photolysis of water is when light energy causes
water to dissociate into protons & electrons & oxygen is produced
H2O ⇌ 2H++ 2e- + ½O2
2) Photoionisation
when light energy excites chlorophyll electrons and raises them to higher energy levels
electrons are lost from chlorophyll
3) Electron transfer chain
electrons pass between electron acceptor protein provide energy for h+ to be pumped into the thylakoid lumen
4) Chemiosomotic theory
proton concentration gradient results in protons diffuse through ATP synthase into the stroma ATP synthase spins releasing the energy to phosphorylate ADP with Pi forming ATP (chemical energy store)
5) the e- and h+ are use dto reduce NADP
167
stages of light independant reaction
calvin cycle
1) CO2 combines with RuBP , catalyzed by Rubisco in stroma
2) form two molecules of Glycerate 3-Phosphate (GP)
3) GP is reduced to Triose Phosphate using ATP and reduced NADP
4) one carbon from Triose Phosphate is removed and goes towards creating a hexose sugar or other organic compunds and the remaining
5) carbons are used to regenerate the RuBP using energy from ATP
168
limiting factors of photosynthesis
light intensity
- amount of light hitting chloroplast
temperature
- enzyme rubisco denature
co2 conc
- co2 to be used if calvin cycle
169
maximising photosynthesis
additional considerations of this
green house with heating to optimal temp of enzyme
fuel burner to produce co2
cost is worth the outcome
170
whats the first step of aerobic respiration
describe process
glycolysis
- in cytoplasm
- glucose is phosphorylated to gp using atp
- this is then converted to troise phosphate
- this then gets oxidised to pyruvate witha net gain of reduced NAD and ATP
171
whats the second step of aerobic respiration
describe process
link reaction
- in mitocondrial matrix
- products of glycolysis actively transported into matrix
- pyruvate gets oxidised to acetate releasing CO and reduced NAD
- acetate combine with coenzyme A this forms acetylcoenzyme A
172
whats the third step of aerobic respiration
describe process
krebs cycle
- in the matrix
- acetylcoenzyme A bind to a 4 carbon molecule and coenzyme A will drop off forming six carbon compound
- from the six carbon compound 2 CO2 released forming 4 carbon compound this also releases 1 reduced FAD and 3 reduced NAD
ATP also phosphorylated via surface level phosphorylation
173
product per glucose molecule
2x krebs cyclye
- 2 reduced FAD
- 6 reduced NAD
- 2 ATP
- 4 co2
174
whats the fourth step of aerobic respiration
describe process
electron transfer chain
- in cristae / inner membrane
- Reduced NAD & reduced FAD are oxidised (electrons lost)
- Electrons transferred down electron transfer chain, along electron carrier proteins that are embedded in the mitochondrial membrane cristae via a series of REDOX reactions occur
- Electrons transfer provides energy to transport protons into the mitochondrial intermembrane space, resulting in a proton concentration gradient
Protons diffuse through ATP synthase, into the matrix
- ATP synthase spins, and the kenetic energy released is used to phosphorylate ADP, forming ATP
– this is Oxidative phosphorylation
- The final electron acceptor in the chain is oxygen
½O2 + 2H+ + 2e- 🡪 H2O
- one molecule of water isd formed
175
describe process of anaerobic respiration
in aminal cells
- in cytoplasm
-glycolysis occur
- glucose is phosphorylated to gp using atp
- this is then converted to troise phosphate
- this then gets oxidised to pyruvate witha net gain of reduced NAD and ATP
- pyruvate reduced (gain H) and the reduced NAD gets oxidised (lose H) and form lactate NAD is reused in glycolysis
176
describe process of anaerobic respiration
in microbes
- in cytoplasm
-glycolysis occur
- glucose is phosphorylated to gp using atp
- this is then converted to troise phosphate
- this then gets oxidised to pyruvate witha net gain of reduced NAD and ATP
- pyruvate reduced (gain H) and the reduced NAD gets oxidised (lose H) and form ethanol and CO2 NAD is reused in glycolysis
177
define biomass
mass of carbon within the organism also known as dry mass
178
what is gpp
gross primary production is the chemical energy stored in the plant biomass
179
whats npp
net primary production
npp= gpp - r
r = energy lost due to respiration
180
how do you calulate the net production for consumers
n = i - ( f + r )
n = net production for consumers
i = chem energy store in ingested food
f = chem energy lost to environment faeces
r = energy lost due to respiration
181
whats the unit of productivity and state why
kg ha–1 yr-1
recorded per unit area to standardise them
per year to take into account of the seasons
182
estimating biomass
1) dry mass
-dry mass is the mass of the organism or tissue after all the water has been removed
-biomass = tot pop * dry mass
2) Calorimetry
- used to estimate the chemical energy stored in dry biomass
- burning the sample of dry biomass this heats a known volume of water
- The change in temperature of the water provides an estimate of the chemical energy the sample contains
183
what are the trophic levels
producer
prim consumer
secondary consumer tertiary consumer
184
why is nitrogen needed in an organism
Plants and animals require nitrogen in order to produce proteins and nucleic acids (DNA and RNA)
185
why are fertiliers needed
each time the crop is harvested nutrients from the soil are removed so using fertilisers replaces vital nutrients
186
suggest two types of fertilisers and advantanges and disadvantages of each
1) organic (manure)
-adv = cheaper often free
-dis = nutrients in unknown quantities
2) artificial
-adv = nutrients in known quantities
-dis = nutrients very soluble so can wash away in rain (leaching)
187
explain environmental impact of leaching
- leachng is when nutrients are washed away by rain into rivers and ponds resulting in eutrophication
- this is when nitrantes stimulate growth of algae create blanket on surface of water blocking light
- prevent plants from photosynthesising on the river bed causing them to die
- decomposer bacteria feed on dead plant matter and respire using up oxygen in the water
- not enough oxygen for animals like fish to breathe so they die
188
whats meant by taxis
DIRECTIONAL response
an organism moves towards/away from a stimulus
189
whats meant by kenesis
random movement
Kinesis refers to the RATE of MOVEMENT
AND the RATE it CHANGES DIRECTION
190
how does iaa affect growth of plant cells
in shoots the side of more iaa will elongate
in roots the side of more iaa will inhibit growth
191
what is positive phototropism and how does it benefit survival
describe how it occurs
growth towards the light
boosts the amount of the light dependant reaction that occurs
as iaa diffuse away from light source / to the side of shade causing these to elongate
192
what is negative phototropism and how does it benefit survival
describe how it occurs
growth away from the light
boosts the root growth this anchors the plant in the soil
as iaa diffuse away from light source / to the side of shade causing these to inhibit growth
193
whats a reflex
what are the main features of a reflex arc
reflex = rapid automatic involuntary movement that keep us from danger
stimuli ~> receptor ~> sensory neurone ~> relay neurone ~> motor neurone ~> effector
194
whats negative / positive gravitropism
negative = away from gravity
iaa diffuse to the bottom cause shoot to grow upwards
positive = towards gravity
iaa diffuse to lower side if root and inhibit growth so grow down
195
name a type of pressure receptor and how they work
pacinian corpuscle
- sensory neurone wrapped in plasma membrane
- stretch mediated Na+ ion channel when pressure is applied to these they get stretched and deformed
- Na+ channel open may lead to establishment of generator potential
196
name a type of light receptor and how they work
1) rods
- black and white images
- rhodopsin pigment must be broken down by light energy
- retinal convergence 3 rods bind to one bipolar neurone results in good low light vision generator potential met easier as there are 3 per 1
- low visual acuity cant see very clearly
2) cones
- coloured images
- three types of cone cell blue, red , green all contain different form of iodopsin pigment that absorb different wavelengths of light
- dont work in dark as not enough light can break down iodopsin as only one cone bond to one bipolar
neurone
- high visual acuity able to destinguish between seperate sources of light
197
distribution of rods and cones
rods are at fovea (center )
cones are at periphery
198
control of heart rate
cardiac muscle is myogenic contract and relax on its own accord
- SAN release wave of depolarisation across atria cause it to contract
- wave reaches AVN causing it to release another wave of depolarisation travels down bundle of his down the septum to Purkyne fibres
- there is a short delay until the second beat allowing atria to pump blood to ventricles
199
location of key areas controlling heart rate
sinoatrial node ( SAN ) - located in right atria known as pacemaker cells
atrioventricular node (AVN) - located between right atria and left ventricle
bundle of his - in septum
Purkyne fibres - in ventricle walls
200
involvement of nervous system in control of heart rate
- medulla oblongata in brain control heart rate via the autonomic nervous system
- this splits into 2
1) sympathetic ns- speeds up heart rate
2) parasympathetic ns- returns heart rate back to normal
201
receptors increasing the heart rate
during exercise blood pH will decrease do to respiration producing carbon dioxide or lactic acid
- heart rate will need to increase in order to remove the acidic conditions so enzymes dont denature
- more impulses sent to the sympathetic nervous system so higher heart rate
if blood pressure is too low then there may be insufficient oxygen concentration being delivered to the respiring cells
- more impulses sent to the sympathetic nervous system so higher heart rate
202
receptors decreasing the heart rate
when blood pressure is too high this may result in damage to the walls of arteries
- more impulses to the parasympathetic nervous system
- slowing heart rate and reducing blood pressure
increase ph detected by chemoreceptors in the medulla oblongata results in decreased signals result in decreased bpm
203
receptors in heart that detect change in ph and blood pressure
pH = chemoreceptors
pressure = pressure receptors
204
features of motor neurone
cell body
dendrites - carry act pot to surrounding cell
axon - carry nerve impulses along neurone
schwann cells - wrap around axon form myelin sheath and doesnt allow charge to pass through
205
key features of nerve impulse
resting potential = -70 mv
depolarisation - Na+ ion channel open they diffuse in and k+ ion channel open they move out voltage exceed the -55 mv threshold and goes up to creating an action potential
repolarisation - Na+ ion channel close and the k+ ion channel open and they keep diffusing out
hyperpolarisation = below -70v
206
establishing resting potential
1) active transport and cotransport of 3 Na+ ions out and 2 K+ ions in
2) create electrochemical gradient
207
whats the all or nothing principle
either act pot created or not they are always the same strength
ensure organism only responds to the stimuli that are large enough to create act pot
208
importance of hyper polarisation
period where act pot cant be created
enusres act pot only goes one direction
209
factors affetcing speed of conduction
1) myelin sheath
- saltatory conduction
jump between node of ranvier
2) axon diameter
- wider diameter less resistance so more speed
3) temperature
- ions diffuse faster and enzymes work at more optimal temperature
210
process of synaptic trasnmission
1) action potential arrive at presynaptic knob
2) depolarisation of presynaptic knob result in ca2+ ion channels opening and these diffuse in
3) vesicles containing neurotransmitter move towards and bind to the presynaptic membrane and neurotransmitter is released to the synaptic cleft
4) neurotransmitter diffuse down conc grad to postsynaptic membrane
5) neurotransmitter bind to the complementary receptor sites on the postsynaptic membrane
6) Na+ ion channel open and they diffuse in may lead to depolarisation
7) neurotransmitter degraded by acetylcholinesterase and released from the receptor Na+ ion channel close and resting potential etablished
211
two types of summation
temporal = one neurone send repeated signals to acheive action potential
summation = many neurones bind to one post synaptic neurone
212
inhibition at a synapse
1) Cl- ions diffuse into postsynaptic neurone and k+ diffuse out
2) result in hyperpolarisation
213
neuromuscular junction
1) presynaptic membrane carries action potential causes calcium ions to diffuse into the neurone
2) This stimulates vesicles containing the neurotransmitter acetylcholine (ACh) to fuse with the presynaptic membrane and get released
3) the acetylcholine diffuses across the neuromuscular junction and binds to receptor proteins on the sarcolemma
3) This stimulates ion channels in the sarcolemma to open, allowing sodium ions to diffuse in
4) results in depolarisation of the sarcolemma, generating an action potential that passes down the T-tubules towards the sarcoplasmic reticulum releases calcium ions
214
how is synaptic transmission unidirectional
1) receptor sites only on the postdynaptic neurone
2) neurotransmitter only released from the presynaptic neurone
215
describe sliding filament model
2) Calcium ions are released from the sarcoplasmic reticulum
3) Calcium ions bind to tropomyosin this change their position revealing the Myosin binding sites on the actin molecules
4) myosin heads bind with these sites, forming actin myosin cross-bridges
5) myosin perfom power stroke and pulls the actin and release adp + pi
6) atp bind to myosin head and it detaches from the actin
7) myosin hydrolyses the atp and myosin heaad returns back to its relaxed state
216
cell division eq
1 * 2*10^number of division
217
differences between the two types of muscle fibre
1) Fast twitch muscle fibres
- contract rapidly
- rely on anaerobic respiration for ATP supply (lactate produce fatigue quickly )
- short bursts of high intensity activity
- fewer capillaries
- large store of glycogen
2) Slow muscle fibres
- contract slower
- rely on aerobic respiration for ATP production
- log duration low intensity
- dense network of capillaries
- small amount of glycogen present
218
regulation of transcription
transcription factors
- bind to promoter sequence of the dna molecule stimulating the rna polymeraise
- results in gene turned on and transcription occurs OR gene turned off and no transcription occurs
219
how is oestrogen a transcription factor
- oestrogen diffuse into cell across phospholipid bilayer as it is a lipid soluble molecule
- oestrogen binds to a complementary receptor on the transcription factor
- this binding results in the transcription factor changing shape and binding to promoter region of the dna
- rna polymeraise is stimulated and phosphodiester bonds form between adjacent rna nucleotides
- mrna molecule is made and then this expresses gene
220
whats RNAi and what is it used for
interfering rna and stops tranlsation of a target gene
join to the mrna molecule via comp base pairing and breaks phosphodiester bonds in the mrna
therefor rna cant be translated and the gene wont be expressed stopping production of polypeptide
221
define epigenetics
- altering in the function of a gene without changing the base sequence of the nucleotides
- these characteristics are also heritable
222
two types of epigenetics and how they affect transcription
decreased acetylation of histones
- stops transcription of the gene as dna coiled too tightly to be transcribed
increased methylation of dna promoter sequence of the molecule
- come from smoking and processed meat
- transcription factor is unable to bind to the promoter sequence as it no longer fits so transcription stops
223
how does menopause result in higher risk of cancer
increased oestrogen and therefor increased transcription as the transcription factorss are activated by the oestrogen and may result in unlimited cell division
may use molecule with complementary shape to block oestrogen binding site on the tf
224
how do mutations result in increased risk of tumors
if mutation occurs in gene coding for proto-oncogene then this is converted to a oncogene and this is constantly activated and results in rapid uncontrollable cell division resulting in a tumor
if mutation / methylation occurs in the promoter sequence in the dna molecule of the tumor supressing gene then these wont be expressed / transcribed result in uncontrollrd cell growth formation of tumor
225
types of mutation
1) addition
- adding an extra nucleotide result in frame shift
2) deletion
- remove a nucleotide result in frame shift
3) inversion
- section of bases is removed from sequence and gets replaced flipped
4) duplication
- when a particular base is duplicated result in frame shift
5) substitution
- a nucleotide is swapped for another one
6) translocation of bases
- section of bases detach from chromosome and join onto a completely different chromosome
226
what is a stem cell
undifferentiated cell that can continually divide and become specialized
227
different types of stem cells and how they divide
totipotent
- produce any type of body cell an unlimited amount of times only in embryo
pluripotent
- divide into almost every cell an unlimited amount of times present in embryos
multipotent
- divide to produce limited amount of cells and divide a limited amount of times
bone marrow
unipotent
- divide to become only one type of cell
cardiomyocites
228
what are induced pluripotent stem cells and how do you make them
- take sample from liver
- switch genes off that made those cells specialized
- cells turned back into pluripotent state
229
what is epigenetics
heritable change in a gene function without changing dna base sequence
230
different types of tumor and their properties
1) benign
dont metatstecise (spread)
divide at a slow rate
2) malignant
do metastacise (spread)
divide at rapid rate
231
how does technology benefit methods of sequencing the genome
automate sequancing and constantly improve efficiency
232
why its easier to determine the genome when studying the proteome of prokaryotes
as they lack introns and all their dna is used to make proteins
233
producing dna fragments
1) reverse transcription
- add many mRNA for specific protein and add reverse transcriptase and free nucleotides
- reverse transcriptase adds complementary nucleooutides to mRNA base sequence
- will have created single stranded cDNA
- dna polymerase is added and forms a double stranded dna as it condense adjacent nucleotides
2) restriction endonuclease
- enzyme cut dna leaving sticky or blunt end
3) gene machine
- dna sequence put into computer and and this creates fragment
234
methods of cloning dna fragments
in another cell
invivo
- cloning inside a living organism
- dna is cut using restriction endonuclease and this leaves sticky end
- promoter region is added and this acts as binding site for rna polymerase to trigger transcription
- terminator sequence must be added at end of the sequence result in rna polymerase to fall off
- the vector is the plasmid in bacteria and same restriction endonuclease is used to cut section out the plasmid so fragment is complementary to this area
- host cell is then heat shocked of added sol of ca ions to increase permeability of the host cell
- vector enter cytoplasm of host cell
235
three possible outcomes of invivo
1) dna sticky ends may have rejoined with itself
2) plasmid sticky ends may rejoin with itself
3) the plasmid and dna combination may have not got into the cell
236
methods of cloning dna fragments
in a machine
invitro / pcr
- temp increased to 95°C and this separates the h bonds between the base pairs form 2 single strands
- decreased to 55°C and this allows primers to attach
- increased to 72°C this is optimal temperature for taq polymeraise to join adjacent nucleotides
237
nephron structure
afferent arteriole ~> glomerulus ~> efferent arterioles
surrounding that glomerulus is the renal capsule ~> proximal convoluted tubule ~> loop of henle ~> distal convoluted tubule ~> collecting duct
capillaries wrap around whole thing
238
function of kidney
- selectively reabsorb the useful molecules back into the kidney and
- wont find proteins or blood cells in the urine as these are too big to be filtered from glomerulus to the renal capsule
239
whats the first step in the nephron
adaptations
1) ultrafiltration
- high hydrostatic pressure in the glomerulus force out water and small molecules into the renal capsule
-filtration first occurs when blood passes through the fenestrations in walls of capillary
-the basement membrane adds another layer of filtration
- podocytes = cells that wrap around the capillary and have tiny gaps adds another stage of filtration
239
whats the second step in the nephron
2) selective re-absorption
- glomerulus filtrate passes through the proximal convoluted tubule and the desired content gets reabsorbed back into the blood
- sodium ion conc is low in pct cell as they are actively transported out of pct into the blood
- sodium ion flow down the conc grad from lumen of pct to the cells in the lining of the pct carry a glucose molecule with it
- glucose then diffuse from lining of the pct to the blood stream
240
whats the third step in the nephron
3) in the loop of henle
- sodium ions actively transported out of the ascending limb
- accumulation of sodium ions outside nephron lower water potential
- water diffuses out and then gets reabsorbed into the blood
decendinng limb the walls are permeable to water as they are much thinner
240
whats the fourth step in the nephron
4) dct and collecting duct
- the sodium ions atcively transported out the loop of henle the filtrate then moves to the distal convoluted tubule and is very dilute
- more water diffuse out of the dct and collecting duct any remaining filtrate forms urine
240
1) checking if the plasmid took up dna fragment
2) checkin that host cell took up the plasmid
marker genes
- specific genes on plasmid
- used to identify if the plasmid took up by host cell
three different types of
marker gene
- antibiotic resistance
- genes coding for flourescent proteins
- genes coding for enzymes
241
using antibiotic resistant marker genes
gene for resistance to tetracycline and ampicillin on a plasmid
the tetracycline resistance gene is deliberately disrupted and no longer functional
grow bacteria on agar tranfer colonies onto amipcillin infused agar transfer the end result onto a second agar block infused with tetracycline
only the bacteria that lived on ampicillin and died on tetracycline have plasmids
241
using flourescent genes in determining if the plasmid has been taken up
flouresent green gene is disrupted by the plasimd that is inserted
no longer flourescent
241
using enzyme markers in determining if the plasmid has been taken up
lactase enzyme makes some things appear blue
gene for the enzyme is inserted into plasmid in middle of gene for the enzyme and this disrupts the gene and the enzyme not created
242
what are dna probes and what are they used for
small sections of dna that are labeled floyrescently or radioactively that can be easily identified in order to locate a specific gene
242
genetic counselling
- screening for prescence of a specific allele
- can be used to give specific medicine
- people may be given advice about thier disorder and what options are available for you
243
genetic fingerprinting
vntr
variable number tandem repeats
repeated sequence in the intron probability of two peole having same one is tiny
243
steps in genetic fingerprinting
1) dna is collected
2) pcr may be used to create larger sample
3) restriction endonuclease enzyme used to cut dna fragment
4) samples put into wells on gel plate and electrical voltage is applied to it
5) the negatively charged dna is attracted to the positive terminal and the shorter peices move further
6) put alkali sol on the gel make dna single stranded
244
what is the first stage of nitrogen cycle
nitrogen fixation
- atmospheric nitrogen turned into ammonium ions
- happens by the nitrogen fixing bacteria that may be free living in the soil or have symbiotic relationship with legumionus plants can live in roots
245
what is the second stage of nitrogen cycle
ammonification
- organic molecules get decomposed and turned into ammonium ions
- carried out by saprobionts
246
what is the third stage of nitrogen cycle
nitrification
- ammonium ions are converted to nitrates then nitrites
247
what is the fourth stage of nitrogen cycle
denitrification
- Denitrifying bacteria use nitrates in the soil during respiration
- This process produces nitrogen gas, which returns to the atmosphere
- only happen in anaerobic conditions
248
how to prevent denitrification
plough feild to aerate it
249
why do we need phosphorus
needed in many biological molecules
250
first step in phosphorus cycle
erosion of rocks release phosphate ions into soil or water
251
second step in phosphorus cycle
plants assimilate/take in phoshate ions
252
third step in phosphorus cycle
plants get eaten by animals and they use the phosphate ions in synthesizing biological molecules
253
fourth step in phosphorus cycle
animals die and phosphate return to the soil
254
fifth step in phosphorus cycle
mineralisation
bacteria in soil break down phosphate ions into inorganic forms
255
sixth step in phosphorus cycle
phosphate ions get washed into water and bet assimilated by plants again
256
define genotype
all the genes within an organism
257
define phenotype
physical expression of the genotype may be influenced by the environment
258
define allele
different forms of the same gene
259
whats monohybrid inheritance
inheritance of one single characteristic controlled by a single gene
260
whats dihybrid inheritance
inheritance of two characteristics control;ed by two genes on two different chromasomes
261
working out a dihybrid question
1) identify the parent genotype
2) do all possible arrangements of each parents alleles
3) cross the 4 pairs over should result in 16=9:3:3:1
262
whats is codominance
both alleles get expressed neither are recessive
263
multiple alleles
some genes have more than 2 alleles
264
sex linkage
a gene that is found on a sex chromasome most genes are carried by the x chromasome
males only have one x so only need one copy of the allele for it to be expressed
265
autosomal linkage
non sex chromasomes
- dont get separated in independant segregation
- if phenotypic ratio is not as expected then likely genes will be linked
- 3:1
266
epistasis
where one gene masks the expression of the other gene
- alleles result in the fucntionality of a protein and will result in the production of colour
267
what is negative feedback
restore system back to origional level
268
why do we need to control blood glucose
affects the water potential of the blood so water may leave or enter cell result in destruction
269
what is glycogenesis
what homone does this
conversion of glucose to glycogen
insulin
270
what is glycogenolysis
what homone does this
hydrolysis of glycogen to glucose
glucagon and adrenaline
271
what is gluconeogenesis
what homone does this
conversion of non carbohydrates into glucose
272
what happens if blood glucose too high
- beta cells in islet of langer hans in the pancreas release insulin
- liver cells become more permeable to the glucose
- glucose get removed from blood stream and is stored as glycogen in the cells (glycogenesis)
273
what happens if blood glucose too low
- alpha cells in islet of langer hans in the pancreas release glucagon and the adrenal gland release adrenaline
- glucagon binds and causes activation of adneylate cyclase which converts ATP ~> cAMP (second messenger )
- cAMP activates protein kinase this hydrolises glycogen into glucose
274
how too high blood glucose may occur
eating too much carbohydrates
275
how too low blood glucose may occur
not eating enough
lost in exercise
276
types of diabetes and how do they occur
type 1
- cell unable to produce insulin
type 2
- cell become resistant to insulin
