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Advanced Higher Biology > Cells And Protiens > Flashcards

Cells And Protiens Flashcards

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1
Q

Hazards in the lab include

A

Toxic or corrosive chemicals
Heat or flammable substances
Pathogenic organisms
Mechanical equipment

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2
Q

We can identify and control measures to minimise risks and reduce hazards by creating a…..

A

Risk assessment

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3
Q

Risk

A

The likely hood of harm arising from the exposure to a hazard

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4
Q

Control measure

A

Using appropriate handling techniques, protective clothing and equipment and aseptic techniques

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5
Q

Linear dilutions

A

Dilutions differ by an equal interval, for example: 0.1, 0.2, 0.3 ect

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6
Q

Log (serial) dilutions

A

Differ by a constant proportion, for example 10^-1, 10^-2, 10^-3 ect

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7
Q

Standard curve

A

Some investigations need you to plot known measurements on a graph to then use to determine unknown values

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8
Q

Buffers

A

A solution where adding acids or alkalis have very small effects on the ph. This allows ph in a reaction mixture to be kept constant

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9
Q

Colorimeters can be used to quantify….

A

Concentration and turbidity

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10
Q

Before use the colorimeters need to be…

A

Calibrated to provide a baseline reading

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11
Q

Centrifuge

A

Samples are spun at increasingly high speeds, sometimes up to 18,000rpm
This separates substances according to density
More dense components settle to form the pellet whilst less dense components remain in the supernatant

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12
Q

Paper and thin layer chromatography

A

Used to separate and identify substances such as amino acids and sugars
The speed that the solute travels along the chromatograph depends on its differing solubility in the solute used

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13
Q

Affinity chromatography

A

Used to separate proteins
A solid matrix or gel column is created with specific molecules (usually receptors) bound to it
Soluble target proteins in a mixture, with a high affinity for these molecules become attached to them as the mixture passes down the column
Non target molecules are washed out

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14
Q

Gel electrophoresis

A

Used to separate proteins and nucleic acids
The samples are backed into hells which have an electric current running through
Charged molecules will move towards the opposing charge
Smaller molecules travel faster and further than larger molecules

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15
Q

Native gels

A

Separate proteins by shape, size and charge and ensure they do not denatured the molecule

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16
Q

SDS-PAGE

A

Separates proteins by size by giving all molecules an equally negative charge and denaturing them

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17
Q

Isoelectric point (IEP)

A

Used to separate proteins from a mixture
IEP is the specific ph at which a soluble protein has no net charge and will precipitate out of a solution
The solution is buffered to a specific PH, only the proteins that have an IEP of that PH will precipitate
This can be used along with electrophoresis as a proteins stops migrating through the gel at its IEP

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18
Q

Immunoassay

A

Used to detect and identify proteins
Uses antibodies with the same specificity known as monoclonal antibodies an antibody specific to the protein antigen linked to a chemical label (or fluorescence or chemiluminescence)
The label is often a reporter enzyme producing a colour change
Can be used to detect diseases

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19
Q

ELISA Techniques

A

Enzyme-linked Immunoabsorbent Assay is an analytical technique using antibodies to detect the presence of an antibody within a soloution
There are thre types, direct, in direct and sandwich

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20
Q

Direct ELISA

A

The antigen is allowed to bind to the surface of a multi well plate
A primary antibody linked to a reporter enzyme is added to the well and binds to the antigen

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21
Q

Indirect ELISA

A

The antigen is allowed to bind to the surface of a multi well plate
A primary antibody is added to the well and binds to the antigen.
A secondary antibody linked to a reporter enzyme is added and binds to the antigen

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22
Q

Sandwich ELISA

A

A capture antibody is allowed to bind to the surface of a multi well plate
The antigen is added and allowed to bind to the capture antibody
A primary antibody binds to the antigen
A secondary antibody linked to a reporter enzyme is added to the well and binds to the primary antibody

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23
Q

Western Blotting

A

Used after SDS-PAGE Electrophoresis
Once the proteins are separated they are transferred or blotted onto a solid medium
Proteins can be identified by ELISA

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24
Q

Bright field microscopy

A

Used to observe whole organisms, parts of organisms, thin sections, dissected tissue or individual cells

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25
Q

Fluorescence microscopy

A

Uses specific fluorescent labels to bind to and visualise certain molecular structures within cells or tissues

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26
Q

Aseptic technique

A

Procedures used in laboratories to reduce contamination as well as the unwanted growth or spread of micro-organisms
Eg sterilisation by heat or chemical

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27
Q

Microbial culture

A

A method of multiplying microorganisms by letting them reproduce in a culture medium under controlled laboratory conditions
Can be started using an inoculum of microbial cells on an agar medium or broth

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28
Q

Animal cells are grown in….

A

A medium containing proteins called growth factors from serum. These promote cell growth and proliferation
These are essential

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29
Q

Primary cell lines can divide a limited number of times whereas tumour cell lines….

A

Can preform unlimited divisions

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30
Q

Serial dilution

A

Allows the number of colonies on solid media to be of a low enough density to be counted

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31
Q

Heamocytometer

A

Specialised microscope cells used to estimate cell numbers in liquid culture

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32
Q

Vital staining

A

Allows a count on living cells only

Dead cells will not absorb the stain

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33
Q

The proteome

A

The entire set of proteins that is , or can be, expressed by a certain genome, cell, tissue, or organism at a certain time

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34
Q

More than one protein can be produced from a single gene due to….

A

Alternative gene splicing

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35
Q

Non coding RNA genes

A

Genes that do not code for proteins

Transcribed to produce tRNA, rNA, and RNA molecules that control the expression of other genes

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36
Q

The set of proteins expressed by a given cell type can vary over…

A

Time and under different conditions

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37
Q

4 factors affecting the set of proteins expressed by a given cell type are:

A

Metabolic activity of the cell
Cellular stress
Response to signalling molecules
Diseased vs healthy cells

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38
Q

The system of internal membranes in Eukaryotic cells ….

A

Increase the total area of the membrane

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39
Q

Because of their size, Eukaryotes have a relatively small…

A

Surface area to volume ratio

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40
Q

The plasma membrane of eukaryotic cells is too small to…

A

Carry out all the vital functions of the cell

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41
Q

Name 13 parts of the cell

A 
Cell membrane 
Golgi apparatus 
Golgi vesicles 
Nucleus 
Lysosome 
Ribosome 
Microtubules
Pinocytotic vesicles
Endoplasmic reticulum 
Centrioles 
Vacuole 
Mitochondria
Smooth endoplasmic reticulum
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42
Q

Endoplasmic reticulum

A

Forms a network of membrane tubules continuous with the nuclear membrane

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43
Q

Golgi apparatus

A

A series of flattened membrane disks

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44
Q

Lysosomes

A

Membrane bound organelles containing a variety of hydrolyses that digest proteins, lipids, nucleic acids and carbohydrates

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45
Q

Vesicles

A

Transport materials between membrane compartments

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46
Q

Parts of the cell involved in synthesis of membrane components

A

Ribosomes
Rough endoplasmic reticulum
Smooth endoplasmic reticulum

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47
Q

Lipids and proteins are synthesised in the…

A

Endoplasmic reticulum

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48
Q

What is the difference between rough endoplasmic reticulum and smooth endoplasmic reticulum?

A

RER has ribosomes on its cytosolic face while SER does not

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49
Q

Lipids are synthesised in…

A

The SER and inserted into its membrane

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50
Q

The synthesis of all proteins begins in the…

A

Cytosolic ribosomes

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51
Q

The synthesis of cytosol proteins is completed in the…

A

Cytosolic proteins, these proteins remain in the cytosol (liquid part of cytoplasm)

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52
Q

Transmembrane proteins

A

Carry a signal sequence which halts translation and directs the ribosome synthesising the protein to dock with the ER forming RER

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53
Q

Signal sequence

A

A short stretch of amino acids at one end on the polypeptide that determines the eventual location of a protein in a cell

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54
Q

Stage one of synthesis of membrane components by RER

A

Proteins are synthesised by ribosomes in the cytoplasm

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55
Q

Stage two of synthesis of membrane components by RER

A

A signal protein (SRP) from the membrane binds to the ribosome and stops translation

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56
Q

Stage three of synthesis of membrane components by RER

A

The SRP binds to the receptor which directs the ribosome to attach to the endoplasmic reticulum forming the RER

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57
Q

Stage four A of synthesis of membrane components by RER

A

Translation restarts and the protein is now inserted into the proteins of the ER

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58
Q

Stage four B of synthesis of membrane components by RER

A

Once translation is fixed the ribosome detaches

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59
Q

Once the proteins in the RER, they are ….

A

Transported by the vesicles that bud off from the ER and fuse with the Golgi apparatus

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60
Q

As proteins move through the Golgi apparatus they undergo…

A

Post translational modification

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61
Q

The major modification of post translational modification is…

A

The addition of carbohydrate groups

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62
Q

Molecules move through the Golgi discs in…

A

Vesicles that bud off from one disc and fuse to the next one in the sack

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63
Q

Enzymes catalyse the addition of various sugars in multiple steps to form

A

Carbohydrates (glyco proteins)

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64
Q

Vesicles that leave the Golgi apparatus take proteins to the…

A

Plasma membrane and lysosome

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65
Q

What do vesicles move along to other membranes and fuse with them within the cell

A

Microtubules

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66
Q

Secreted proteins are translated in the … way

A

Ribosomes on the RER and enter it’s lumen

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67
Q

Examples of secreted proteins

A

Peptide hormone

Digestive hormone

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68
Q

Describe the secretory pathway

A

The proteins move through the Golgi apparatus and are then packed into secretory vesicles. These vesicles move to fuse with the plasma membrane, releasing the proteins out of the cell

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69
Q

Many secreted proteins are synthesised as inactive proteins and require….

A

proteolytic cleavage to produce active proteins

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70
Q

Proteolytic cleavage

A

Another type of post translational modification

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71
Q

Give examples of secreted proteins that require proteolytic cleavage to become active

A

Digestive enzymes

Insulin

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72
Q

Describe the structure of proteins

A

Polymers of amino acid monomers

Amino acids are linked by peptide bonds to form polypeptides

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73
Q

Amino acids have the same basic structure but differ in…

A

The R groups present

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74
Q

R groups vary in…

A

Size, shape, charge , hydrogen bonding capacity and chemical reactivity

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75
Q

Amino acids are classified according to their R groups, like:

A

Basic (positively charged)
Active (negativity changed)
Polar
Hydrophobic

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76
Q

The wide range of functions carried out by proteins results from the diversity of…

A

Amino acid R groups

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77
Q

Primary structure

A

The sequence in which the amino acids are synthesised into the polypeptide

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78
Q

Hydrogen bonds along the backbone of the protein strand results in…

A

Regions of secondary structure

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79
Q

Some secondary structures of proteins are…

A

Alpha helices
Parallel or anti parallel beta pleated sheets
Turns

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80
Q

A polypeptide folds into a tertiary structure. This conformation is stabilised by …

A

Interactions between R groups

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81
Q

The tertiary structure of polypeptides is stabilised by interactions between R groups such as..

A 
Hydrophobic interactions
Ionic bonds
London dispersion forces 
Hydrogen bonds
Disulphide bridges (consistent bonds between R groups containing sulphur)
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82
Q

Quaternary structure

A

Exists in proteins with two or more connected poly peptide subunits
Describes the spread arrangement of the subunits

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83
Q

Prosthetic group

A

Ia nonpolar unit tightly bound to a protein and necessary for it to function for example the molecule haemoglobin

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84
Q

Haemoglobin

A

Iron containing oxygen transporting protein present in the red blood cells of almost all vertebrates

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85
Q

The ability of haemoglobin to binds to oxygen is dependent upon…

A

The non protein haem group

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86
Q

Interactions of the R groups can be influenced by

A

Temperature and pH

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87
Q

Increasing the temperature of a protein…

A

Disrupts the interactions that hold the protein and shape the protein begins to unfold eventually becoming denatured

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88
Q

The charges on acidic and basic R groups are affected by pH. As pH increases or decreases from the optimum….

A

The normal ionic interactions between charged groups are lost which gradually changes the confirmation of the protein until it becomes denatured

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89
Q

Ligand

A

A substance that can bind to a protein

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90
Q

R groups not involved in protein folding can allow…

A

Bonding to Ligands. The binding sites will have a complimentary shape and chemistry to the ligand

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91
Q

As a ligand binds to a protein binding site the confirmation of the protein changes this change in confirmation causes a….

A

Functional change in the protein

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92
Q

Allosteric

A

Interactions which occur between spatially distinct sites

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93
Q

The binding of a substrate molecule to one active site of an allosteric enzyme increases…

A

The affinity of the other active sites for Binding of subsequent substrate molecules

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94
Q

The activity of allosteric enzymes can vary greatly with…

A

Small changes in the substrate concentration

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95
Q

Many allosteric proteins consist of

A

Multiple subunits which means they have a quaternary structure

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96
Q

Allosteric proteins with multiple subunits sure cooperativity and binding. what is this?

A

Changes in binding at one subunit alter the infinity of the remaining subunits

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97
Q

Allosteric enzymes contain a second type of site called…

A

An allosteric site

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98
Q

Modulators

A

Regulate the activity of the enzyme when they binds to the allosteric site

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99
Q

What is the effect of a modulator

A

The confirmation of the enzyme changes and this alters the affinity of the active site for the substrate

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100
Q

Positive modulators

A

Increase the enzymes affinity for the substrate (activation)

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101
Q

Negative modulators

A

Decrease the enzymes affinity for the substrate (inhibitors)

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102
Q

Give an example of a molecule that shows cooperativity

A

Haemoglobin

103
Q

What combination of shift of pH and temperature will lower the affinity of haemoglobin for oxygen

A

A decrease in pH and an increase in temperature

104
Q

Reducing the binding of oxygen in actively respiring tissue to haemoglobin will promote

A

Increased oxygen delivery to tissue

105
Q

The addition of removal of phosphate can cause…

A

Reversible confirmational changes in proteins this is a common form of post-translational modification

106
Q

Protein kinases

A

Catalyse the transfer of aphosphate group to other proteins

107
Q

Which phosphate of ATP is transferred to specific R groups in the protein

A

Terminal phosphate

108
Q

Protein phosphaleses

A

Catalyse the reverse reaction to protein kinases

109
Q

Phosphorylation

A

Beings about confirmational changes which can affect. the activity of many cellular proteins such as enzymes and receptors are regulated in this way. some proteins are activated by phosphorylation but others are inhibited

110
Q

Adding A phosphate group adds…

A

Negative charges.

Ionic interactions in the unphosphorylated protein can be disrupted a new one is created

111
Q

Fluid mosaic model

A

A model that describes the structure of a cell membrane

112
Q

Name parts of a cell membrane

A 
Integral glycoprotein
Carbohydrates 
Membrane channel
Peripheral protein 
Integral protein
113
Q

What holds Integral membrane proteins in the phospholipid bilayer

A

Regions of hydrophobic R group allow strong hydrophobic interact that hold them in

114
Q

Integral membrane proteins

A

Interact extensively with the hydrophobic region of membrane phospholipids
Some integral membrane proteins are transmembrane proteins which mean they span the entirety of the cell

115
Q

Peripheral membrane proteins

A

Peripheral membrane proteins have hydrophilic R group on their surface and are bound to the surface of membranes, mainly by ionic and hydrogen bond interactions. Many peripheral proteins interact with the surface of integral membrane proteins

116
Q

Phospholipid bilayer

A

The phospholipid bilayer is a barrier to ions and most unchanged polar molecules
Some small molecules, such as oxygen and carbon dioxide, pass through the bilayer by simple diffusion

117
Q

Transport proteins

A

Facilitated diffusion is the passive transport of substances across membrane through specific transmembrane proteins

118
Q

To perform specialised functions, different cell types have different….

A

Channels and transporter proteins

119
Q

Channels

A

Multi-subunit proteins with the subunits arranged to form water-filled pores that extend across the membrane

120
Q

Most channel proteins in plants and animals are highly selective. This means

A

They let very few types of molecules pass through

121
Q

Some channel proteins are gated, this means…

A

They change conformation to allow or prevent diffusion

122
Q

Ligand gated channels

A

Controlled by the binding of signal molecules

123
Q

Voltage gated channels

A

Controlled by changes in ion concentration

124
Q

Transporter proteins

A

Bind to the specific substance to be transported and undergo a conformational change to transfer the solute across the membrane

125
Q

Transporters alternate between two conformation so that…

A

The binding site for a solute is sequentially exposed on one side of the bilayer, then the other

126
Q

Active transport

A

Uses pump proteins that transfer substances across the membrane against their concentration

127
Q

Pumps that mediate active transport

A

Transporter proteins coupled to an energy source

128
Q

What is required for active transport

A

Metabolic energy

129
Q

Some active transport proteins hydrolyse ATP directly to provide…

A

The energy for conformational change required to move substances across the membrane

130
Q

ATPases

A

The enzymes used to hydrolyse ATP for active transport

131
Q

For a solute carrying a net charge the concentration gradient and the electrical potential difference (voltage) …

A

Combine to form the electrochemical gradient that determines the transport of the solute

132
Q

The electrochemical gradient

A

Forms due to the net positive charge outside the cell and the net negative charge inside the cell

133
Q

Membrane potential

A

(An electrical potential difference)

Created when there is a difference in electrical charge on the two sides of the membrane

134
Q

Where does the energy for the sodium potassium pump come From and what is used for?

A

The hydrolysis of ATP

To establish and maintain ion gradients

135
Q

Sodium potassium pump

A

Transports ions against a steep concentration gradient using energy from ATP hydrolysis
Transports sodium ions out of the cell a potassium ions into the cell

136
Q

Describe the first stage of the sodium potassium pump

A

The pump has high affinity for sodium ions inside the cell

Binding occurs and the pump is phosphorylated by ATP

137
Q

Describe the second stage of the sodium potassium pump

A

The confirmation of the protein changes and the affinity for sodium ions decreases. This means the sodium ions are released outside of the cell

138
Q

Describe the third stage of the sodium potassium pump

A

The potassium ions bind outside the cell

139
Q

Describe the fourth stage of the sodium potassium pump

A

Dephosphorylation occurs and the conformation of the protein changes

140
Q

Describe the fifth stage of the sodium potassium pump

A

Potassium ions are taken into the cell and the affinity returns to start

141
Q

How is the electrical and chemical gradient established in the sodium potassium pump

A

For each ATP hydrolysed, three sodium ions are transported out of the cell and two potassium ions are transported into the cell

142
Q

The sodium potassium pump is found in most animal cells, accounting for…

A

…a high proportion of the basal metabolic rate in many organisms

143
Q

What is the role of the sodium potassium pump in the small intestine

A

The sodium gradient created by the sodium potassium pump drives the active transport of glucose

144
Q

Describe the process of the sodium potassium pump in the small intestine

A

In intestinal epithelial cells the sodium potassium pump generates a sodium ion gradient across the plasma membrane.
The glucose transporter responsible for this glucose symport transports sodium ions and glucose at the same time in the same direction
Sodium ions enter the cell down their concentration gradient.
The simultaneous transport of glucose pumps glucose into the cell against its concentration gradient

145
Q

Hydrophobic

A

Molecules that are seemingly repelled by a mass of water.

These molecules are known as non-polar

146
Q

Hydrophobic signalling molecules

A

Can diffuse directly through the phospholipid bilayer of membranes, and so bind to the intercellular receptors. These receptors are transcription factors

147
Q

Transcription factors

A

Protein that when bound to DNA can either stimulate or inhibit initiation of transcription

148
Q

Examples of hydrophobic signalling molecules

A

Oestrogen

Testosterone

149
Q

Steroid hormones bind to…

A

Specific receptors in the cytosol or the nucleus

150
Q

What happens after a steroid hormone bonds to a receptor

A

The hormone-receptor complex moves to the nucleus where it binds to specific sites on DNA and effects gene expression

151
Q

Hormone response elements (HRE’s)

A

The hormone receptor complex of steroid hormones binds to this specific DNA sequences
Binding at these sites influences the rate of transcription, with each steroid hormone affecting the gene expression of many different genes

152
Q

Hydrophilic

A

A molecule that is attracted to water molecules and tends to be dissolved by water
also known as a polar molecule

153
Q

Hydrophilic signal molecules

A

Binds to transmembrane receptors and do not enter the cystol

examples of hydrophilic extracellular signalling molecules are peptide hormones and neurotransmitters

154
Q

Transmembrane receptors change confirmation when…

A

The ligand binds to the extracellular face

155
Q

The signal molecule does not enter the cell but

A

Is transduced across the plasma membrane

156
Q

Transduction

A

A process by which a chemical or physical signal is transmitted through a cell by a series of molecular events resulting in a cellular response

157
Q

Transmembrane receptors

A

Act as signal transducers by converting the extracellular ligand binding event into intercellular signals which alters the behaviour of the cell

158
Q

Transduced hydrophilic signals

A

Involve G proteins or cascades of phosphorylation by kinase enzymes

159
Q

G-proteins

A

Really signals from activated receptors

160
Q

Activated receptors

A

Receptors that have bound a signal molecule to target the proteins such as enzymes and ion channels

161
Q

Phosphorylation cascades

A

allow more than one intercellular signalling pathway to be activated involve a series of events with one Kinase activating the next in the sequence and so on
phosphorylation cascades can result in the phosphorylation of many proteins as a result of the original signalling event

162
Q

What happens when insulin binds to its receptor hormone

A

The binding of the peptide hormone insulin to its receptor results in an intercellular signalling cascade that triggers recruitment of GLUT 4 glucose transporter proteins to the cell membrane of fat and muscle cells

163
Q

Step one of the binding of insulin

A

Binding insulin to its receptor causing a conformation change that triggers phosphorylation of the receptor

164
Q

Step two of the binding of insulin

A

The phosphorylation of the receptor starts a phosphorylation cascade inside the cell

165
Q

Step three of the binding of insulin

A

This phosphorylation eventually leads to GLUT 4- containing vesicles being transported to the cell membrane

166
Q

Diabetes mellitus can be caused by…

A

Failure to produce insulin (type 1) or loss of sensitivity (type 2)

167
Q

Type 2 diabetes is generally associated with…

A

Obesity

168
Q

How does exercise help treat type 2 diabetes

A

Exercise triggers recruitment of GLUT 4, so can improve the uptake of glucose to fat and muscle cells

169
Q

What is the cause of type 1 diabetes

A

Body fails to produce insulin

170
Q

What is the cause of type 2 diabetes

A

Receptors do not respond to insulin

171
Q

What is the treatment of type 1 diabetes

A

Daily insulin injections

172
Q

What is the treatment of type 2 diabetes

A

Controlled diet and exercise

173
Q

Nerve impulse

A

A signal transmitted along a nerve fibre

174
Q

Resting membrane potential

A

A state where there is no net flow of ions across the membrane

175
Q

The transmission of a nerve impulse requires….

A

Changes in the membrane potential of the neurons plasma membrane

176
Q

Action potential

A

A wave of electrical excitation along a neurons plasma membrane

177
Q

Neurotransmitters

A

Chemicals that transmit a signal across a synapse (a gap between two neurons)

178
Q

Neurotransmitters initiate a response by…

A

Binding to their receptors (ligand gated ion channels) at a synapse

179
Q

Name things involved in a nerve impulse

A 
Neurotransmitter
Neurotransmitter transporter 
Synaptic vesicle
Voltage gated Ca2+ channel
Post synaptic destiny 
Receptor 
Axon terminal
Synaptic cleft
Dendrite
180
Q

Depolarisation

A

A sudden change in membrane potential, usually from a relatively negative to positive change

181
Q

Depolarisation of the plasma membrane as a result of the entry of positive ions triggers…

A

The opening of voltage gated sodium channels and further depolarisation occurs

182
Q

Inactivation of the sodium channels and the opening of potassium channels restores…

A

The resting membrane potential

183
Q

Binding of a neurotransmitter triggers the opening of

A

Ligand gated ion channels at a synapse

184
Q

Fast chemical synapses contain…

A

Inotropic receptors

185
Q

Ion movement occurs when there is…

A

Depolarisation of the plasma membrane

186
Q

If sufficient ion movement occurs, and the membrane is depolarised Beyond a threshold value…

A

The opening of the voltage gated sodium channels is triggered and sodium ions enter the cell down their electrochemical gradient.
This leads to a rapid and large change in membrane potential.
A short time after the opening, the sodium channels become inactivated voltage gated potassium channels, then open to allow potassium ions to move out of the cell to restore the resting membrane potential

187
Q

What is the first stage of the restoration of Resting membrane potential

A

Stimulus starts the rapid change in voltage or action potential
This much reach above a threshold voltage to start membrane depolarisation

188
Q

What is the second stage of the restoration of Resting membrane potential

A

Depolarisation is caused by a rapid rise in membrane potential opening of sodium channels in the cellular membrane, resulting in a large influx of sodium ions

189
Q

What is the third stage of the restoration of Resting membrane potential

A

Membrane depolarisation results from rapid sodium channel inactivation as well as a large efflux of potassium ions resulting from activated potassium channels

190
Q

What is the fourth stage of the restoration of Resting membrane potential

A

Hyper polarisation is a lowered membrane potential caused by the efflux of potassium ions and the closing of the potassium channels

191
Q

What is the fifth stage of the restoration of Resting membrane potential

A

Resting stage is when membrane potential returns to the resting voltage that occurred before stimulation occurred

192
Q

Depolarisation of a patch of membrane causes neighbouring regions of membrane to..

A

Depolarise and go through the same cycle, as adjacent voltage gated sodium channel are opened

193
Q

When the action potential reaches the end of the neuron it causes….

A

Vesicles containing neurotransmitters to fuse with the membrane, this releases neurotransmitter which stimulates a response in a connecting cell

194
Q

Restoration of the resting membrane potential allows….

A

The inactive voltage gated sodium channels to return to a conformation that allows them to open again in response to depolarisation of the membrane

195
Q

Ion concentration gradients are re-established by …

A

The sodium potassium pump which activity transports ions in and out of the cell

196
Q

Following repolarisation the sodium and potassium ion gradients are…

A

Reduced

197
Q

The sodium potassium pump restores the…

A

Sodium and potassium ions back to resting potential levels

198
Q

Name parts of the eye

A 
Choroid 
Retina
Fovea
Optic nerve
Ciliary body
Iris
Lense
Pupil
Cornea
199
Q

Retina

A

The area of the eye that detects light and contains two types of photo receptor: rods and cones

200
Q

Rods

A

Function in dim light but do not allow colour perception

201
Q

Cones

A

Responsible for colour vision and only function in bright light

202
Q

How are the photo receptors in animals formed

A

The light sensitive molecule retinal is combined with the protein ops in

203
Q

In rod cells the retinal-Opsin complex is called

A

rhodopsin

204
Q

Retinal absorbs a photon of light and…

A

Rhodopsin changes conformation to photoelectrical rhodopsin. A cascade of proteins amplifies the signal

205
Q

A single Photo excited rhodopsin actives…

A

Hundreds of molecules of G-protein called transducin

206
Q

A Transducin molecule activates

A

A single molecule of the enzyme phosphodiesterase (PRE)

207
Q

PDE catalyses…

A

The hydrolysis of a molecule called cyclic GMP (cGMP)

208
Q

Each active PDE breaks down…

A

Thousands of cGMP molecules per second

209
Q

The reduction in cGMP concentration as a result of its hydrolysis affects…

A

The function of the ion channels in the membrane of the rod cells, resulting in their closure

210
Q

The closure of ion channels the the membrane of rod cells triggers…

A

Nerve impulses in nerves in the retina

211
Q

A very high degree of amplification results in…

A

Rod cells being able to respond to low intensities of light

212
Q

In cone cells, different forms of ops in combine with retinal to give different…

A

Photoreceptor proteins, each with a maximal sensitivity to specific wavelengths: red, blue, green and uv

213
Q

Describe step one of a nerve impulse in the vertebrae eye…

A

Light stimulation of rhodopsin leads to activation of a G-protein (transduction)

214
Q

Describe step two of a nerve impulse in the vertebrae eye…

A

Activated G protein activate cGMP

Phosphodiesterase (PDE)

215
Q

Describe step three of a nerve impulse in the vertebrae eye…

A

PDE hydrolyses cGMP, reducing its concentration

216
Q

Describe step four of a nerve impulse in the vertebrae eye…

A

This leads to closure of the Na+ channels

217
Q

Cytoskeleton

A

A complex network of protein filaments that gives mechanical support and shape to cells

218
Q

The cytoskeleton consists of

A

Different protein structures including microtubules which are found in all eukaryotic cells

219
Q

Microtubules

A

Hollow cylinder is composed of the protein tubulin

We they radiate from the Microtubule organising centre (MTOC) (centrosome)

220
Q

Microtubules control

A

The movement of membrane-bound organelles and chromosomes

221
Q

Microtubules also form

A

The spindle fibers that are active during cell division

This means that the cytoskeleton needs to be remodelled during cell division

222
Q

The formation and breakdown of microtubules involves

A

Polymerisation and depolymerisation of tubulin

223
Q

The cell cycle consists of

A

Interphase and mitotic phase (M phase)

224
Q

Which is shorter than the mitotic phase or the interphase

A

The mitotic phase

225
Q

Interphase involves

A

Growth and DNA synthesis

226
Q

Name the stages of interphase

A

G1, S, G2

227
Q

G1

A

Growth phase

228
Q

S

A

The phase or DNA is replicated (synthesis)

229
Q

G2

A

Second growth phase

230
Q

The mitotic phase involves

A

Mitosis and cytokinesis

231
Q

Mitosis

A

The separation of chromosomal material by the spindle microtubules

232
Q

Cytokinesis

A

Separation of the cytoplasm into two daughter cells

233
Q

Mitosis consists of

A

Prophase
Metaphase
Anaphase
Telophase

234
Q

Prophase

A

DNA condenses into chromosomes, each consist of two sister chromatids.
nuclear membrane breaks down spindle microtubules extend from the MTOC by polymerisation and attach to chromatids via their kinetochores in the centromere region

235
Q

Metaphase

A

Chromosomes are aligned the metaphase plate

236
Q

Anaphase

A

As spindle microtubules shorten by depolarisation, sister chromatids are separated and the chromosomes are pulled to opposite poles

237
Q

Telophase

A

The chromosomes decondense and nuclear membranes form around them

238
Q

Checkpoints

A

Mechanisms within the cell that assess the condition of the cell during the cell cycle and halt progression to the next phase until certain requirements are met

239
Q

Cyclin proteins

A

Accumulate during cell growth and are involved in regulating the cell cycle

240
Q

Cycling combine with and activate….

A

Cyclin dependent kinases (CDKs)

241
Q

Active cyclin-CDK complexes…

A

Phosphorylate proteins that regulate progression through the cycle. If sufficient for formulation is reached progression occurs

242
Q

G1 checkpoint

A

Retinoblastoma protein acts as a tumour suppressor by inhibiting the transcription of genes that code for proteins needed for DNA replication.
Phosphorylation by G1 cyclin inhibits the retinoblastoma protein. This allows transcription of genes that code for proteins needed for DNA replication so cells progress from G1 to S phase

243
Q

G2 checkpoint

A

The success of DNA replication and any damage to DNA is assessed.
Do you any damage triggers the activation of several proteins including PS3 That can stimulate DNA repair, Arrest the cell cycle or cause cell death.
If this checkpoint passes the sale progresses from G2 to M phase

244
Q

Metaphase checkpoint

A

Controls progression from metaphase to anaphase
Here progression is halted until the chromosomes are Aligned correctly on the metaphase plate and attached to the spindle microtubules

245
Q

I don’t controlled reduction in the rate of the cell cycle may result in

A

Degenerative disease for example Alzheimer’s disease

246
Q

An uncontrolled increase in the rate of the cell cycle may result in

A

Tumour formation

247
Q

Proto-oncogenes

A

And normal gene usually involved in the control of cell growth and division which can mutate to form a tumour promoting oncogene

248
Q

Apoptosis

A

The death of cells which occurs as a normal and controlled part of an organisms growth and development

249
Q

Apoptosis is triggered by

A

Cell death signals that can be external or internal

250
Q

External death signals

A

The production of this signal molecules from lymphocytes as an example of an external death signal. the death signal molecules bind to a surface receptor protein and trigger a protein cascade within the cytoplasm

251
Q

Internal death signals

A

Do you any damage is an example of an internal death signal

And internal death signal resulting from DNA damage causes the activation of PS3 tumour suppressor protein

252
Q

Both types of death signal result in

A

The activation of caspases (Types of protease enzyme) That cause the destruction of the cell

253
Q

Apoptosis is essential during the development of an organism to remove….

A

Sales no longer required as development progresses or during metamorphosis

254
Q

Cells may initiate apoptosis in the absence of

A

Growth factors

Advanced Higher Biology (3 decks)

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