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1
Q

Why do electron microscopes produce images with higher resolution?

A

Electrons have smaller wavelength

Pass through objects more often

2
Q

Scanning electron microscope features?

A

3D image
100,000-500,000 x magnification
3-10nm resolution

3
Q

Transmission electron microscope?

A

No 3D image
500,000- 2,000,000 x magnification
0.2-0.5nm resolution

4
Q

Resolution:

A

Shortest distance between 2 objects that can be distinguished by the viewer

5
Q

Formula for image size (value you get with ruler)?

A

Image size= magnification x Size of object in reality (very small)

6
Q

value of a mm?

A

1 metre x 10^-3

7
Q

value of a um?

A

1 metre x10^-6

8
Q

Value of nm?

A

1 metre x 10^-9

9
Q

Prokaryotic cell=

A

In single celled organisms
DNA= supercoiled
Ribosomes= 70s, not 80s
Cell wall= peptidoglycan

10
Q

3 types of monosaccharides:

A

Triose
Pentose
Hexose (glucose)

11
Q

How’s Alpha glucose structure different

A
Draw 2 X's and add chimney on left
Carbon 1= Carbon at very right
There are OH groups on C1, C2, and C4
In Alpha OH group on C1 bellow plane
In Beta OH group on C1 above plane
12
Q

Glycosidic bond=

A

When 2 monosaccharides bond to form a disaccharide undergoing a condensation reaction

13
Q

Alpha glucose + Alpha glucose =

A

Maltose

14
Q

Alpha glucose + Fructose =

A

Sucrose

15
Q

Alpha glucose + Galactose =

A

Lactose

16
Q

Benedict’s test for reducing and non reducing sugars

A

Heat with benedict’s solution, if present blue to brick red

If no colour change, boil with HCl, which hydrolyses any sucrose present into fructose, and glucose
Nuetralise with sodium carbonate
Do benedict’s test again

17
Q

Test for starch?

A

Add Iodine solution

If present blue/black colour forms

18
Q

Triglyceride structure?

A

1 glycerol unit

3 fatty acid side chains

19
Q

Structure of glycerol?

A

3 carbons, each with an OH bonded on the same side, rest are hydrogen

20
Q

Fatty acid structure?

A

Hydrocarbon chain with carboxylic acid one side, and methyl group the other

21
Q

Phospholipid structure?

A

Same as triglycerides except one fatty acid chain replaced by phosphate group

22
Q

Example of a sterol?

A

Cholesterol

23
Q

How do synthesised proteins leave cell?

A

Synthesised on ribosome bonded to ER
They pass into it’s cisternae and packaged into transport vehicles
Move to Golgi apparatus with help from cytoskeleton
Proteins structurally altered and leave again via vesicles
Secretory vesicles take it to cell membrane where leave via exocytosis

24
Q

3 components of cytoskeleton?

A

Micofilaments
Microtubules
Intermediate fibres

25
Q

Structure of an amino acid?

A

NH2 CRH COOH
Amine group
R group
Carboxylic acid

26
Q

Peptide bond:

A

Bond between 2 amino acids ( covalent between amine and carboxylic acid)
Condensation reaction
Peptidly transferase

27
Q

Biuert test:

A

Sample mixed with equal amounts of NaOH solution
CuSO4 added until blue
Left still, if lilac colour appears protein is present

28
Q

Primary structure:

A

The sequence of amino acids in a polypeptide, determines final shape of protein

29
Q

Secondary strucure

A

The folding and coiling caused by hydrogen bonding between Nitrogen, Hydrogen and Oxygen of nearby aminos
(alpha helix, Beta pleated sheet)

30
Q

Tertiary structure=

A

Further folding of secondary structure, by bonds and interactions between R groups

Hydrogen bonds
Hydrophobic/phallic interactions
Disulphide bonds (cysteine)
Ionic bonds

31
Q

Quaternary structure:

A

Level of structure when 2 or more polypeptide subunits are bonded together

32
Q

Denaturation of a protein:

A

Increase in thermal energy
Increase in Kinetic energy
Bonds in tertiary structure will start to vibrate more and break
Weakest to strongest (hydrogen to disulphide)
As bonds break tertiary structure breaks down

33
Q

Nucleotide:

A

5 Carbon sugar
Phosphate group
Organic nitrogenous base

34
Q

Prymidines:

A

Single ring structure

Thymine and Cytosine

35
Q

Purines

A

Double ring structure

Adenine and Guanine

36
Q

A-T

A

2 Hydrogen bonds

37
Q

C-G

A

3 hydrogen bonds

38
Q

Differences in DNA and RNA

A

DNA:
Bases are AT CG
Deoxyribose sugar
Double stranded

RNA:
Bases are AU CG
Ribose sugar
Single stranded

39
Q

DNA replication

A

Enzyme helicase unwinds and unzips the 2 strands of DNA
By breaking hydrogen bonds between base pairs
Each new strand acts as template for new strands to be made against
Free DNA nucleotides hydrogen bond to templates via complementary base pairing
Enzyme DNA polymerase catalyses condensation between sugar and phosphate group, creating sugar phosphate backbone
= Semi conservative
Strands run in 2 opposite directions:
Leading strand=continueous replication
Lagging strand= replication done in okazaki fragments

40
Q

Why is DNA replication semi conservative?

A

2 DNA molecules made from one molecule, with one new and one old strand

41
Q

What’s replication;

A

DNA copies it self exactly

42
Q

What’s transcription?

A

Making mRNA by transferring the code of the gene onto the mRNA single strand

43
Q

Stages of transcription?

A

RNA helicase unwinds and unzips 2 strands of DNA being transcribed
Free RNA nucleotides hydrogen bond to antisense strand via complementary base pairing (AU, CG)
RNA polymerase catalyses condensation reaction between Ribose and Phosphate to form sugar phosphate backbone
mRNA leaves nucleus via nuclear pore, and travels to ribosome for translation

44
Q

Stages of translation?

A

Ribosome binds to mRNA at the beginning of strand at start codon
mRNA carries the code for synthesising the polypeptide
Sequence of bases on mRNA read in 3’s, (triple codons)
tRNA molecules each carry a specific amino acid, and have an anticodon on other side
tRNA lines up with opposite to correct codon via base pairing rule
Ribosomes catalyse reaction between adjacent amino acids forming peptide bonds
Process continues until stop codon reached
Polypeptide created

45
Q

4 Factors which affect rate of reaction in enzymes?

A

pH
Temp
Substrate conc
Enzyme conc

46
Q

Facillitated diffusion=

A

movement of molecules from a region of high concentration to low
Down a conc gradient
Uses carrier and intrinsic proteins

47
Q

How do carrier proteins work

A

Molecule/ion being transported binds to receptors of the channel of the carrier protein
Atp binds to carrier protein, and is hydrolysed into ADP and phosphate
Binding of Phosphate causes protein to change shape, opeining it up to inside of cell
Molecules/ions released into cell
Phosphate released and binds with ADP to form ATP

48
Q

Cytolysis

A

Animal cell bursting

49
Q

Crenation

A

Animal cell shrinking

50
Q

Plasmolysis

A

Plant cell shrinkning, protoplast pulled away from cell wall

51
Q

Stages of interphase

A

G1,S,G2

52
Q

G1

A

Protein synthesis
Organelles replicate
Cell grows

53
Q

S phase

A

DNA replicated in nucleus

54
Q

G2:

A

Cell continues to grow

Duplicated DNA checked for errors

55
Q

Prophase:

A

Chromatin condenses to form chromosomes, nucleolus and nucleus break down
Spindle fibres move centromers into centre of cell
Nuclear envelope disappears

56
Q

Metaphase:

A

Chromosomes moved by spindle fibres to form metaphase plate

57
Q

Anaphase:

A

Centromers holding pair of chromosomes divide

Shortening spindle fibres pull them to opposite ends of cell

58
Q

Telophase

A

Chromatids reached poles and are now chromosomes
2 new sets of chromosomes assemble at each pole
Chromosomes uncoil, nucleolus forms

Cytokinesis occurs

59
Q

Order of cell division?

A

Prophase, metaphase, anaphase, telophase, cytokenesis

60
Q

Prophase 1:

A

Chromosomes condense
Homologous chromosomes pair up in a process called synapsis to form bivalents
Crossing over occurs, arms of chromatids mix

61
Q

Metaphase 1:

A

Bivalents attach to spindle fibres, and are randomly arranged along spindle

62
Q

Anaphase 1:

A

Homologous chromosomes separated

Centromers pulled to opposite sides of cell

63
Q

Telophase 1:

A

Chromatids uncoil, nuclear envelope forms

64
Q

Mitosis forms?

A

2 Genetically indentical haploid cells

65
Q

Meitosis forms?

A

4 genetically different diploid cells

66
Q

What’s a totipotent cell?

A

Can differentiate into any cell eg. zygote

67
Q

What’s a pluripotent cell?

A

Can form all tissue types, but not whole organism eg. early embryos

68
Q

Multipotent cell?

A

Can only form a range of cells within a tissue type eg.bone marrow

69
Q

Inspiration:

A

Diaphragm contracts, flattening and lowering
Intercostal muscles contract, ribs move upwards
Volume of thorax increased, pressure decreased
Air moves in

70
Q

Expiration

A

Diaphragm relaxes, moves to dome shape
Intercostal muscles relax, ribs move downwards
Volume of thorax decreased, pressure increased
air forced out

71
Q

Tidal volume=

A

air that moves in and out of lungs with each resting breath

72
Q

Vital capacity=

A

volume of air that can be breathed when strongest exhalation followed by strongest inhalation

73
Q

Inspiratory reserve volume=

A

Maximum volume you can breathe in over and above normal inhalation

74
Q

Expiratory reserve volume=

A

Extra amount of air you can force out of lungs above tidal volume

75
Q

Residual volume=

A

Volume of air left in lungs after strongest exhalation

76
Q

Total lung capacity=

A

Sum of vital capacity and residual volume

77
Q

How do fish maintain water flow when they stop moving?

A

Mouth opens, increasing volume of buccal cavity, pressure drops water moves in
Operculum valves containing, cavity containing gills expands and lowers
Buccal cavity moves back up, increasing pressure so water flows over gills

78
Q

Counter current system=

A

Water and blood flow in opposite directions maintaining concentration gradient

79
Q

Blood going through heart:

A

Vena cava to Right atrium
To right ventricle through tricuspid valve
To pulmonary artery and lungs through semi lunar valve
Enters via pulmonary vein, to left atrium, to left ventricle through mitrial valve
Then Aorta though semi lunar valve then the rest of the body

80
Q

How CO2 transferred in blood?

A

CO2 + Water = carbonic acid
Carbonic acid dissociates into H+ ions and HCO3 - ions
HCO3 - ions move out of cell via diffusion Cl - ions move in, maintain electrical balance= chloride shift
This maintains conc gradient for more CO2 to move in
When erythrocytes reach lungs carbonic acid back to it’s reactants, CO2 and Cl- move out

81
Q

Cardiac cycle=

A

Diastole-atria then ventricles fill up with blood

Systole- atria and ventricles contract, blood goes out of aorta and pulmonary artery

82
Q

How is heart beat maintained

A

Sino-atrial node sends out electrical excitation, atria contract
Non conducting tissue prevents it reaching ventricles
Electricity picked up by atrio ventricular node, reaches bundle of his (conducting tissue in septum)
Branch out from bottom of ventricles causing them to contract

83
Q

Late blight

A

fungus

84
Q

Black sigatoka

A

fungus

85
Q

TB

A

bacteria

86
Q

Meningitus

A

Bacteria

87
Q

What substance seperates of infected plant cells

A

callose

88
Q

Blood clotting

A

Tissue damaged
Platelts activated
Fibrin causes clot

89
Q

Inflamation

A

Mast cells produce cytokines which attract phagocytes
Mast cells make histamines which make blood vessel walls more leaky leading to swelling
Dilation of blood vessels= increased temp

90
Q

Humoral response

A

Pathogen enters body, engulfed by macrophages, non self antigens now present on it
B and T cells which are complementary to non self antigens bind on and are cloned T helper cells secrete cytokines, and B cells make clones
B cells become plasma cells and secrete antibodies killing infection, or become memory cells

91
Q

Cell meditated response

A

Self antigens turned into non self
Virus invades host cell, non self antigen present on cell
Complementary T cell binds to non self antigen, and divides my mitosis
Differentiates into killer helper and memory cells
Killer kill
helper cytokines

92
Q

Antibody

A
C= constant never changes binds to phagocyte
V= variable where antigens bind to