Unit 1 Flashcards
(117 cards)
1
Q
What is a hazard
A
Something that can cause harm
2
Q
What are examples of a hazard in the lab
A
Substances, organisms, or equipment
3
Q
What is risk
A
The likelihood of harm arising from a hazard
4
Q
What is a risk assessment, why do we do them, and what do we do in them
A
A risk assessment is conducted to reduce the likelihood or harm arising from an experiment by identifying and controlling hazards to reduce risk
5
Q
What are he two types of dilution
A
Linear and log
6
Q
When would a linear dilution be used
A
When the substance being diluted is the independent variable in an experiment
7
Q
How do linear dilutions differ
A
By an equal interval, eg., 0.2, 0.4, etc
8
Q
When would a log dilution be used
A
When needing to estimate the concentration or density of cells in a sample
9
Q
How do log dilutions differ
A
By a constant proportion (eg., 10-1, 10-2, 10-3…)
10
Q
What is colorimetry used to determine
A
Concentration or turbidity of a solution
11
Q
What is turbidity
A
A measure of the degree by which a fluid loses transparency due to the presence of suspended particles
12
Q
Why are buffers used
A
To prevent small changes in pH
13
Q
What is centrifugation used to separate
A
Substances based on density
14
Q
What are the two components involved in a centrifuged solution
A
The supernatant (less dense matter) and the pellet (denser matter)
15
Q
What is Thin layer/Paper Chromatography used to separate
A
Amino acids or sugars
16
Q
What does affinity chromatography separate
A
A target protein from a mixture of proteins
17
Q
How is affinity chromatography performed
A
The solution of mixed proteins is passed through a column containing molecules specific to the target protein (such as antibodies of ligands). The target proteins have a high affinity to the molecules in the column, so bind. The non-target proteins lack this affinity, so do not bind. The column is then washed, and the target proteins extracted.
18
Q
What are the two types of gel electrophoresis
A
Native and SDS-PAGE
19
Q
Do native gels denature the protein being tested?
A
No
20
Q
What do native gels separate by
A
Size, shape and charge
21
Q
How does SDS-PAGE work
A
The proteins being tested are denatured (preventing any further function) and a negative electrical field is applied to the medium. The native proteins move towards a positive electrode at the other end of the medium.
22
Q
What does SDS-PAGE separate by
A
Size alone
23
Q
What is Isoelectric point
A
The pH at which a protein has no net charge, and precipitates out of solution
24
Q
How can proteins be identified using their IEP’s
A
By buffering a solution to a specific pH, any proteins with the corresponding IEP will precipitate out of solution and can thus be identified.
25
What are immunoassay techniques used for
Identifying specific proteins
26
What are monoclonal antibodies
Antibodies with the same specificity as each other
27
What do reporter enzymes do
Induce a colour change in the target molecule
28
Explain what Western Blotting is, and when it is used.
After SDS-PAGE, the separated proteins are transferred to a solid medium and a specific antibody (containing a reporter enzyme) attached.
29
What is bright-field microscopy used to identify
Whole organisms, parts of organisms, thin sections of tissues, or individual cells
30
What is fluorescent microscopy used to identify, and what does it use to do it
Using fluorescent labels, it visualises certain molecules, or structures within cells
31
What is the purpose of aseptic technique
Elimination of unwanted microbial contamination
32
What are the two possible mediums that can be used to start a cell culture
An agar plate/medium, or a broth containing suitable nutrients
33
A primary cell line has how many divisions?
Limited
34
A tumour cell line has how many divisions?
Unlimited
35
WHat is a haemocytometer used for
To estimate cell numbers
36
What is vital staining used for
To distinguish between living and dead cells
37
How are living and dead cells identified using vital staining
Living/viable cells sill remain unstained, but dead cells will be stained.
38
How is the structure of a protein determined
By the order of amino acids
39
What is the proteome
The entire set of proteins expressed by the genome
40
Why is the proteome larger than the number of genes
Because more than one protein can be produces by a single genes as a result of alternative RNA splicing
41
What are the factors that affect the proteins expressed by a cell
Metabolic activity, cellular stress, responses to signalling molecules and whether the cell is diseased or healthy
42
How are amino acids joined together
By peptide bonds
43
What are the four types of R group, and what do they mean for the protein
Basic (additional NH2)
Acidic (additional COOH)
Polar (additional OH)
Hydrophobic (additional chain of CH3's)
44
What is primary structure
The sequence in which amino acids are synthesised into a protein
45
What is secondary structure
When parts of the protein begin to fold into certain shapes, held together by hydrogen bonds
46
What is tertiary structure
The protein after it fully folds, held together by interactions between R group
47
What interactions between R groups hold a tertiary protein together
Hydrogen bonds
LDF's
Disulfide bridges
Hydrophobic interactions
Ionic bonds
48
What is quaternary structure
When one or more subunits of a protein join together
49
What is a prosthetic group
A non-protein unit that binds to a protein, and is necessary for its function
50
What can R groups that are not involved in the folding of the protein do?
Allow for ligand binding
51
How does a change in binding at one allosteric site affect the other allosteric sites in an allosteric enzyme showing co-operativity
A change in binding at one site (binding or release) will affect the binding of the other sites of the protein.
52
What is a modulator
A ligand that binds to the allosteric site of a protein, affecting the enzymes affinity for the substrate and thus affecting activity
53
What is special about heaemoglobin
It shows co-operativity in binding
54
How does a decrease in pH, or an increase in temperature, affect haemoglobin
It reduced its affinity for oxygen, reducing the binding of oxygen in each subunit.
55
Why is a lowered affinity of oxygen a good thing for muscle cells
It allows more oxygen to leave the blood and go to the muscle cells
56
What do protein kinases do
Catalyse the transfer of a phosphate group from one protein to another (phosphorylation)
57
What do protein phosphatases do
Catalyse the transfer of a phosphate group from one protein to another (dephosphorylation)
58
What is the fluid mosaic model
The model showing the phospholipid bilayer of a cell membrane
59
Is a phospholipids tail hydrophobic or hydrophilic?
Hydrophobic
60
Is a phospholipids head hydrophobic or hydrophilic?
Hydrophilic
61
Where are integral proteins held, and how are they held there
Within the membrane, held by strong hydrophobic interactions between the hydrophobic tails of the phospholipids and the hydrophobic R groups on the proteins surface.
62
Where are peripheral proteins held, and how are they held there
On the outside of the membrane, held by hydrophilic interactions between the R groups on their surface
63
Where do most peripheral proteins reside on the membrane, in relation to integral proteins
Many peripheral proteins interact with the surface of integral proteins
64
What is the phospholipid bilayer a barrier to
Ions and most uncharged polar molecules
65
What molecules can pass through the layer, and what type of diffusion do they use to do it
Small molecules like oxygen and carbon dioxide, using simple diffusion to move through the membrane
66
What is facilitated diffusion
The passive transport of substances across the membrane through specific proteins
67
What are the two types of gated channel
Ligand gated and voltage gated
68
How do gated channels allow or prevent diffusion
By changing conformation
69
How do voltage gated channels move substances across the membrane
Using changes in ion concentrations
70
How do ligand gated channels move substances across the membrane
Using the binding of signal molecules
71
How do transporter proteins work
They bind to specific substances and undergo a conformational change to transport the solute across the membrane
72
What is an electrochemical gradient
The concentration gradient and the electrical potential difference (the difference between charges on two molecules) combined
73
How do ion pumps establish and maintain ion gradients
By using energy from the hydrolysis of ATP, they move ions across the membrane
74
What are receptor molecules
Proteins with a binding site for a specific signalling molecule
75
How does signal molecule binding affect the receptor, and what does this do
Signal molecule binding changed the conformation of the receptor, which initiated a response from within the cell
76
Do hydrophobic signalling molecules target intracellular receptors or extracellular receptors (are they lipid soluble or lipid insoluble )
Being lipid soluble, hydrophobic signalling molecules target intracellular receptors
77
What are the receptors for hydrophobic signalling molecules, and what do they do
The receptors are transcription factors, and they are proteins that either initiate or inhibit protein transcription
78
What are some examples of hydrophobic signalling molecules
Steroid hormones, such as oestrogen and testosterone
79
What does the signalling molecule form when binding to the receptor
The hormone-receptor complex (HRC)
80
Where does the HRC move to, where does it bind, and what does it do
It moves into the nucleus, binding to specific hormone response elements (HRE's) that affect the rate of transcription, and the proteins produced by the cell
81
Do hydrophilic signalling molecules target intracellular receptors or extracellular receptors (are they lipid soluble or lipid insoluble )
Being lipid insoluble, hydrophilic signalling molecules target extracellular receptors
82
What are some examples of hydrophilic signalling molecules
Peptide hormones, eg. Insulin, and neurotransmitters, eg noradrenaline and acetylcholine
83
What happens to the receptor upon binding with the signal molecule
It changes conformation
84
What does the receptor do to the signal?
Transduces the signal, converting the extracellular signal into an intracellular signal and transducing it across the membrane
85
What are the two methods of signal transduction
G-protein cascade or phosphorylation cascade
86
How do G-proteins function
They relay the signal from the receptor to target proteins, such as an enzyme or ion channels
87
How do phosphorylation cascades relay a signal
One kinase enzyme phosphorylates another in a chain until the target protein is phosphorylated and activated
88
What hormone is involved in the control of blood glucose levels, and where it is produced
Insulin, produced in the pancreas
89
What happens within the cell when insulin binds to its receptor, and what does this mean for the cell
The receptor changes conformation and a signalling cascade occurs, triggering the recruitment of GLUT4 transporters to the membrane of the cell. This allows glucose to be transported into muscle and fat cells
90
Explain type 1 Diabetes Mellitus
Present from birth and caused by the inability to produce insulin. Must be treated using direct injections of insulin into the body
91
Explain type 2 Diabetes Mellitus
Begins later in life and generally associated with obesity. Caused by a loss of function in insulin receptors, it is often treated with changes in an individuals lifestyle, such as an increase in exercise
92
How does an increase in levels of exercise improve blood glucose regulation
Triggers the recruitment of GLUT4 transporters, allowing more glucose to enter fat and muscle cells
93
What is the resting potential
The state of a neuron where there is no net flow of ions across the cell's plasma membrane
94
What is an action potential
A wave of excitation along the nerves plasma membrane, caused by a rapid change in a neurons electrical potential difference
95
Describe the electrical potential of the inside and outside of a neurons plasma membrane
The inside is more negative than the outside, which is less negative/more positive
96
What does the cytoskeleton do, and what does it consist of
It gives mechanical support and structure to the cell, and includes microtubules
97
What proteins are microtubules made from
Tubulin
98
Where do microtubules radiate from
The Microtubule organising centre (MTOC) or the centrosome
99
What is a proto-oncogene, and what can it mutate to form
It is a normal gene that is usually involved in the process of cell growth and division, and it can mutate into a tumour-promoting oncogene
100
What are the two phases of the cell cycle
Mitotic (M) phase and Interphase (G1, G2 and S phase)
101
What do cyclins do, and how they they interact with cyclin-dependant kinases (CDK's)
Cyclins accumulate in the cell during cell growth and activate CDK's to form cyclin-CDK complexed. These complexes phosphorylate proteins that regulate progression of the cell cycle. If sufficient phosphorylation occurs, then the cell cycle progresses
102
What are the four stages of mitosis, and what is the other stage in the mitotic phase
PMAT - prophase, metaphase, anaphase, telophase. Cytokinesis comes after
103
What happens during prophase
DNA condenses into chromosomes (two sister chromatids) and the nuclear membrane begins to break down. Spindle fibres attach to the kinetochores of the chromosomes in their centrosome region
104
What happens during metaphase
The chromosomes are aligned at the metaphase plate
105
What happens during anaphase
Spindle fibres depolymerise and shorten, pulling the chromosomes apart to the poles of the cell
106
What happens during telophase
The chromosomes start to decondense and a nuclear membrane starts to reform around the two new groups of chromosomes
107
What happens during cytokinesis
The nuclear membrane divides to make two daughter cells
108
What is the purpose of the G1 checkpoint
Ensure that the cell has grown enough to produce two daughter cells upon dividing
109
What occurs during G1 checkpoint
Retinoblastoma protein (Rb) usually acts as a tumour suppressor, inhibiting the transcription of genes that allow for DNA replication. Cyclin-CDK complexed phosphorylate Rb, which inhibits it, allowing the cell to produce proteins required for DNA replication. If there are enough cyclins in the cell, then the checkpoint will be passed
110
What is checked during the G2 checkpoint
The success of DNA replication is assessed, and any damage to DNA is recognised.
111
What occurs during the G2 checkpoint
If DNA is found to be damaged, then p53 will activate. p53 will stimulate DNA repair, arrest the cell cycle, or induce apoptosis
112
What does the metaphase checkpoint check for
The chromosomes correctly aligned at the metaphase plate. If they are not aligned correctly, then the cell cycle will not continue
113
How does an external cell death signal induce apoptosis
It binds to a specific receptor triggering a protein cascade with produces caspases.
114
How does an internal cell death signal induce apoptosis
It causes the activation of p53, which causes a caspase cascade
115
What type of enzyme are caspases
Proteases
116
Why is apoptosis essential during development
As it removes cells no longer required, such as in metamorphosis
117
What is another condition for a cell to initiate apoptosis
Absence of growth factors
