Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BIOLOGY OCR A > Module 2 > Flashcards

Module 2 Flashcards

Cell structure, Biological molecules, Nucleotides, Enzymes, Plasma membrane, Cell division

1
Q

What is a microscope?

A

Instrument that allows an object to be magnified

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

When was the first light microscope developed

A

16th to 17th century

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

When was the first cell observed, by who

A

1665, Robert Hooke

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

When was the first living cell observed

A

1674

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

When was the first nucleus observed, by who

A

1833, Robert Brown

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

When was the universal cell theory made, what is it

A

1873, “all living things are composed of cells and cell products

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How does a light microscope work?

A

Two lenses, objective and eyepiece. Light passes through the specimen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is magnification

A

How much bigger the image is then the actual object

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is resoloution

A

The ability to distinguish between two objects

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is magnification and resolution of a light microscope

A

Magnification up to 2000
Resolution of 200nm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the equation for magnification

A

AIM M = Image size/Actual size

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the difference between dry and wet mounts, examples

A

Dry mount - thin small samples are placed on the slide with a coverslip on top. Eg hair/pollen
Wet mount - Specimens are suspended in liquid, coverslip is placed at an angle. Eg aquatic samples

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is a squash slide, example

A

Wet mount, a soft sample is squashed between two slides, creating a thin layer of cells. Eg Root tips

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is a smear slide, example

A

A wet mount, the edge of a different slide is used to smear a sample, creating a thin, even layer of cells. Eg blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Why is it important to stain light microscope samples

A

increase contrast between organelles, by being absorbed more or less by different components

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How to stain a slide

A

Sample is allowed to air dry, then passed through a flame, the specimen is now adhered to the slide, and will take up the stain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are crystal violet and methylene blue attracted to?

A

Negatively charged materials in cytoplasm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are Congo red and Nigrosin attracted to

A

Repelled by negatively charged cytosol, so dye stains outside of cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What does differential staining do

A

Distinguishes between two types of organisms that would otherwise be harder to identify

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the risks of staining

A

Many stains are an irritant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How should scientific drawing be drawn?

A

Title, magnification, sharp pencil, white unlined paper, big drawing, smooth continuous lines, no shading, clearly defined structures, proportions are correct, label lines do not cross and do not have arrow heads and are parallel tot the top of a page, with a ruler

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is an eyepiece graticule

A

Glass disk with a scale of 1 to 100, which has no units. The relative size of the divisions increase in magnification, but it remains unchanged

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is a stage micrometer

A

Microscope slide with a scale in micrometers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Explain how to calibrate a light microscope

A

Put the stage micrometer in place and the eyepiece graticule in the eyepiece, align them
See where the scales line up on both scales, calculate the graticule division (number of micrometres/number of graticule divisions)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How does an transmission electron microscope work

A

A beam of electrons passed through the specimen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is the magnification/resolution of a TEM

A

x500,000, 3-10nm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

How does a scanning electron microscope work

A

A beam of electrons is sent across surface of a specimen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is the magnification/resolution of a SEM

A

x500,000, 3-10nm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Compare light microscopes and electron microscopes

A

Light
Small/portable
Simple sample prep
Up to x2000, 200nm
Specimens are living or dead

Electron
Expensive
Large
Complex sample prep, distorts material
Vacuum needed
Black and white images
x500,000,
Specimens are dead

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

How does a laser scanning confocal microscope work

A

moves a spot of focused light over a specimen, fluorescence from dyed areas, which are filtered through a pinhole aperture, Only light from close is sharp, from far away it is blurry, but these both have the same focal plane, so it is not blurry

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is the advantage of laser scanning

A

Non invasive, used in development of new drugs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is a fluorescent tag? What is an advantage?

A

glowing under UV light. Allows for more precision

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is a cell?

A

Basic unit of all life

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is the difference between prokaryotic and eukaryotic

A

Prokaryotic - single celled organisms with no membrane bound organelle
Eukaryotic - multicellular organisms with membrane bound organelle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Cell structure:
Describe the structure of the nucleus.

A

● Surrounded by a nuclear envelope
● Nuclear pores allow substances to enter/exit.
● Dense nucleolus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Cell structure:
Describe the function of the nucleus.

A

● Contains DNA in the form of chromosomes.
● Controls cellular processes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Cell structure:
Describe the function of the nucleolus.

A

producing ribosomes, composed of proteins and RNA, which is used to made rRNA and combined with proteins to make ribosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Cell structure:
Describe the structure and function of the endoplasmic reticulum (ER).

A

● Cisternae: network of tubules & flattened sacs extends from cell membrane & connects to nuclear envelope:
● Rough ER: many ribosomes attached for protein synthesis & transport.
● Smooth ER: lipid synthesis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Cell structure:
Describe the structure and function of the Golgi apparatus.

A

● Modifies & packages proteins for export.
● Synthesises glycoproteins.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Cell structure:
Describe the structure and function of ribosomes.

A

Formed of protein & rRNA.
Have large subunit which joins amino acids & small subunit with mRNA binding site.
Protein synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Cell structure:
Describe the relationship between the organelles involved in the production and synthesis of proteins

A

The ribosomes that synthesise proteins are attached to the rER. Vesicles transport proteins to the cis side of the Golgi apparatus, which modifies proteins for secretion via (secretory) vesicles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Cell structure:
Describe the structure of a mitochondrion.

A

● Surrounded by double membrane.
● Folded inner membrane forms cristae
● Fluid matrix: contains mitochondrial DNA, respiratory enzymes, lipids, proteins.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Cell structure:
Describe the structure of a chloroplast.

A

● Double membrane.
● Thylakoids: flattened discs stack to form
grana, containing chlorophyll
● lamellae: tubes attach thylakoids in adjacent grana.
● Stroma: fluid-filled matrix.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Cell structure:
State the function of mitochondria and chloroplasts.

A

● Mitochondria: site of aerobic respiration to produce ATP.
● Chloroplasts: site of photosynthesis
to convert solar energy to chemical energy.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Cell structure:
Describe the structure and function of a lysosome.

A

Hydrolytic enzyme removes waste products

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

Cell structure:
Describe the structure and function of a plant cell wall.

A

● Made of cellulose (support plant)
● Plasmodesmata form pathway to allow molecules to pass between cells.
● Middle lamella separates adjacent cell walls.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Cell structure:
What are bacterial and fungal cell walls made of?

A

bacteria: peptidoglycan (murein)
fungi: chitin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

Cell structure:
Describe the structure and function of centrioles.

A

● Spherical group of 9 microtubules arranged in a 9+2 arrangment
● Located in centrosomes.
● Migrate to opposite poles of cell during prophase & spindle fibres form between them.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Cell structure:
Describe the structure and function of flagella.

A

● made of the protein flagellin.
● Rotates to move (unicellular)
organism.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

Cell structure:
Describe the structure and function of cilia.

A

● protrusions on eukaryotic cells.
● Move back and forth rhythmically to sweep foreign substances / movement.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

Cell structure:
Why is the cytoskeleton important?

A

● Provides mechanical strength.
● Aids transport within cells.
● Enables cell movement.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

Cell structure:
Compare eukaryotic and prokaryotic cells.

A

Both have:
● cell membrane
● cytoplasm
● ribosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

Cell structure:
Contrast eukaryotic and prokaryotic cells.

A

Prokaryotic:
0.5-5µm
DNA is circular with no proteins, in the cytoplasm
Cell division occurs by binary fission - no spindle involved
70s ribosomes
No membrane bound organelles
Cell wall is made from peptidoglycan and murein

Eukaryotic
100µm
DNA is associated with proteins, and formed into proteins (linear)
Cell division occurs by mitosis or meiosis involves spindle fibres (Separate chromosomes)
80s ribosomes
Membrane bound organelles, and not membrane bound organelles
Cell wall is present in plants (cellulose), fungi (chitin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

Cell structure:
Describe the structure and function of the cell-surface plasma membrane.

A

‘Fluid mosaic’ phospholipid bilayer with extrinsic & intrinsic proteins embedded.
● Acts as a barrier
● Semi permeable
● Involved in cell signalling / cell recognition.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

Cell structure:
Explain the role of cholesterol, glycoproteins & glycolipids in the cell- surface membrane.

A

● Cholesterol: steroid molecule connects phospholipids & reduces fluidity.
● Glycoproteins: cell signalling, cell recognition (antigens) & binding cells together.
● Glycolipids: cell signalling & cell recognition.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

Biological Molecules:
How do hydrogen bonds form between water molecules?

A

Water is polar Forms O 𝛿- (slightly negative) & H 𝛿+ (slightly positive).
There are intermolecular forces of attraction between a on O 𝛿- of one molecule & H 𝛿+ on an adjacent molecule.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

Biological Molecules:
State 7 biologically important properties of water.

A

● reaches maximum density at 4℃
● high surface tension
● incompressible
● solvent for chemical reactions
● high specific heat capacity
● high latent heat of vaporisation
● cohesion between molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

Biological Molecules:
Why is the incompressible nature of water important for organisms?

A

Provides turgidity to plant cells.
Provides hydrostatic skeleton for some small animals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

Biological Molecules:
Explain why ice floats on water. Why is this important for organisms?

A

Ice is less dense than water because H-bonds hold molecules in fixed positions further away from each other.
Insulates water in arctic climates so aquatic organisms can survive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

Biological Molecules:
Why is the high surface tension of water important for organisms?

A

Slows water loss due to transpiration in plants.
Water rises in narrow tubes, lowering demand on root pressure.
Some insects can ‘skim’ across the surface of water.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

Biological Molecules:
Why is water an important solvent for organisms?

A

Polar universal solvent dissolves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

Biological Molecules:
Why are the high specific heat capacity and latent of vapourisation of water important for organisms?

A

Cooling effect when water evaporates from skin surface as sweat/ from mouth when panting.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

Biological Molecules:
Define monomer and polymer. Give some examples.

A

monomer: smaller units that join together to form larger molecule
● monosaccharides (glucose, fructose, galactose, ribose)
● amino acids
● nucleotides
polymer: molecules formed when many monomers join together
● polysaccharides
● proteins
● DNA/ RNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

Biological Molecules:
What happens in condensation and hydrolysis reactions?

A

Condensation: chemical bond forms between 2 molecules & a molecule of water is produced.

Hydrolysis: a water molecule is used to break a chemical bond between 2 molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

Biological Molecules:
Name the elements found in carbohydrates, lipids, proteins and nucleic acids.

A

carbohydrates & lipids: C, H, O
proteins: C, H, O, N, S
nucleic acids: C, H, O, N, P

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

Biological Molecules:
Draw the structure of ⍺-glucose and 𝛽-glucose.

A

:)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

Biological Molecules:
Describe the properties of 𝛼 glucose.

A

● Small & water soluble

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

Biological Molecules:
Draw the structure of ribose.

A

:)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

Biological Molecules:
What type of bond forms when monosaccharides react?

A

(1,4 or 1,6) glycosidic bond
● 2 monomers = 1 chemical bond = disaccharide.
● Multiple monomers = many chemical bonds = polysaccharide.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

Biological Molecules:
Describe how disaccharides form.
Name 3 disaccharides.
Molecular formula

A

Condensation reaction forms glycosidic bond between 2 monosaccharides.
● maltose: glucose + glucose
● sucrose: glucose + fructose
● lactose: glucose + galactose
all have molecular formula C12H22O11

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

Biological Molecules:
Describe the structure and functions of starch.

A

Storage polymer of 𝛼-glucose in plant cells:
● insoluble
● large
made from amylose:
● 1,4 glycosidic bonds
● helix
and amylopectin:
● 1,4 & 1,6 glycosidic bonds
● branched = many ends for hydrolysis into glucose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

Biological Molecules:
Describe the structure and functions of glycogen.

A

Store of 𝛼-glucose
● 1,4 & 1,6 glycosidic bonds.
● Branched = many ends for hydrolysis.
● Insoluble
● Compact.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

Biological Molecules:
Describe the structure and functions of cellulose.

A

Polymer of 𝛽-glucose gives rigidity to plant cell walls
● 1,4 glycosidic bonds.
● Straight-chain, unbranched molecule.
● Alternate glucose molecules are rotated 180°.
● H-bond crosslinks between parallel strands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

Biological Molecules:
How do triglyglcerides form?

A

Condensation reaction between 1 molecule of glycerol &
3 fatty acids
forms ester bonds.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

Biological Molecules:
Contrast saturated and unsaturated fatty acids.

A

Saturated:
● contain only single bonds
● straight-chain molecules
● higher melting point = solid at room temp
● found in animal fats
Unsaturated:
● contain C=C double bonds
● ‘kinked’ molecules
● lower melting point = liquid at room temp
● found in plant oils

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

Biological Molecules:
Relate the structure of triglycerides to their functions.

A

● High energy:mass ratio = energy storage
● Insoluble hydrocarbon chain = waterproof plants
● Slow conductor of heat = thermal insulation
● Less dense (floats) water = buoyancy of aquatic animals.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

Biological Molecules:
Describe the structure and function of phospholipids.

A

glycerol attached to 2 hydrophobic fatty acid tails & 1 hydrophilic polar
phosphate head.
● Forms phospholipid bilayer in water = component of membranes.
● Tails can splay outwards = waterproofing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

Biological Molecules:
Are phospholipids and triglycerides polymers?

A

No. They are macromolecules.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

Biological Molecules:
Describe the structure and function of cholesterol.

A

Steroid structure of 4 hydrocarbon rings. Hydrocarbon tail on one side, hydroxyl group (-OH) on the other side.
Adds stability to cell surface phospholipid bilayer by connecting molecules & reducing fluidity.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

Biological Molecules:
What is the general structure of an amino acid? Draw it

A

-COOH carboxyl group
-R variable side group
-NH2 amine group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
81
Q

Biological Molecules:
How do polypeptides form?

A

Condensation reactions between amino acids form peptide bonds
(-CONH-)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
82
Q

Biological Molecules:
Define ‘primary structure’ of a protein.

A

Primary: straight chain of amino acids, determined by sequence of codons on mRNA.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
83
Q

Biological Molecules:
Describe the 2 types of secondary protein structure.

A

α-helix:
● All N-H bonds on same side of protein chain.
● Spiral shape.
● H-bonds parallel to helical axis.
β-pleated sheet:
● N-H & C=O groups alternate from one side to the other.
● Pleated sheet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
84
Q

Biological Molecules:
Define ‘tertiary structure’ of a protein. Describe the bonds present.

A

3D structure formed by further folding
● Disulfide bonds: strong covalent S-S bonds (cysteine only)
● Ionic bonds: strong bonds between charged R groups
● Hydrogen bonds: numerous & easily broken.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
85
Q

Biological Molecules:
Define ‘quaternary structure’ of a protein.

A

● May consist of more than one polypeptide.
● Precise 3D structure held together by the same types of bond as tertiary structure.
● May involve addition of prosthetic groups

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
86
Q

Biological Molecules:
Describe the structure and function of globular proteins.

A

● Spherical & compact.
● Hydrophilic R groups face outwards & hydrophobic R groups face inwards = water-soluble.
● Involved in metabolic processes (enzymes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
87
Q

Biological Molecules:
Describe the structure of haemoglobin.

A

● Globular conjugated protein with prosthetic group.
● 2 𝛼-chains, 2 𝛽-chains, 4 prosthetic haem groups.
● Water-soluble
● Fe2+ haem group bonds with O2.
● Tertiary structure changes so it is easier for O2 to bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
88
Q

Biological Molecules:
Describe the structure and function of fibrous proteins.

A

● Can form long chains or fibres.
● Insoluble in water.
● Useful for structure and suppor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
89
Q

Biological Molecules:
List the functions of collagen, elastin and keratin.

A

Collagen: component of bones, cartilage, tendons.
Elastin: provides elasticity to connective tissue, arteries, skin, lungs,
Keratin: structural component of hair, nails, hooves/ claws,

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
90
Q

Biological Molecules:
Describe how to test for proteins in a sample.

A

Biuret test #
1. Add biurets regenat
3. Positive result: colour changes from blue to purple
Negative result: solution remains blue.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
91
Q

Biological Molecules:
Describe how to test for lipids in a sample.

A
  1. Dissolve solid samples in ethanol.
  2. Add an equal volume of water and shake.
  3. Positive result: milky white emulsion forms
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
92
Q

Biological Molecules:
Describe how to test for reducing sugars.

A
  1. Add an equal volume of Benedict’s reagent to a sample.
  2. Heat the mixture in an electric water bath at 100℃ for 5 mins.
  3. Positive result: colour changes from blue to orange & brick-red precipitate forms.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
93
Q

Biological Molecules:
Describe the Benedict’s test for non-reducing sugars.

A
  1. Negative result: Benedict’s reagent remains blue.
  2. Add Hydrochloric acid
  3. Heat in a boiling water bath for 5 mins.
  4. Neutralise the mixture using sodium carbonate solution.
  5. Proceed with the Benedict’s test as usual - positive test means non-reducting sugar
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
94
Q

Biological Molecules:
Describe the test for starch.

A
  1. Add iodine solution.
  2. Positive result: colour changes from orange to blue-black.
    Negative - orange
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
95
Q

Biological Molecules:
How can the concentration of a solution be measured quantitatively?

A

● Use colorimetry to measure absorbance/%transmission. use a calibration curve from solutions of known concentration.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
96
Q

Biological Molecules:
Outline the process of paper chromatography.

A
  1. spot solution onto pencil ‘start line’ (origin) 1 cm above bottom of paper.
  2. Place chromatography paper in solvent.
  3. Allow solvent to run until it almost touches other end of the paper.
    Molecules in mixture move different distances based on relative solubility in solvent/attraction to paper.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
97
Q

Biological Molecules:
What are Rf values? How can they be calculated?

A

Ratios that allow comparison of how far molecules have moved in chromatograms.
Rf value = distance between origin / distance between origin and solvent front.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
98
Q

Biological Molecules:
What is ATP, what does it do

A

Adenosine triphosphate, nitrogenous base, pentose sugar, and 3 phosphate groups

Releases immediate energy, by breaking the bond between phosphate groups forming ADP, during a hydrolysis reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
99
Q

Biological Molecules:
What is the ATP reaction to release energy

A

ADP + water -> ADP + P + energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
100
Q

Biological Molecules:
What is phosphorylation

A

ADP attaching to a phosphate group, during a condensation reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
101
Q

Biological Molecules:
What is some properties of ATP

A

Small - moves in and out of cells
Water soluble - happens in aqueous environments
Intermediate energy - used in cellular reactions
Releases is small quantities - not wasted as heat
Easily recharged

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
102
Q

Biological Molecules:
What is semiconservative replication

A

Two new molecules of DNA are formed, each with one old strand of DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
103
Q

Biological Molecules:
Explain DNA replication

A

DNA helicase unzips two strands of DNA, free nucleotides in the nucleoplasm attach to their complementary base, DNA polymerase creates phosphodiester bonds between bases, Products are identical and contain one original strand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
104
Q

Biological Molecules:
How are Okazaki fragments formed

A

DNA polymerase can only bind to the 3’ side, so moves from 3’ 5’ direction. The 5’ to 3’ (lagging strand) strand DNA polymerase has to wait until another section has been unwound. (discontinuous replication)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
105
Q

Biological Molecules:
What happens to Okazaki Fragments

A

Ligase join Okazaki fragments on the lagging strands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
106
Q

Biological Molecules:
What is DNA mutation?

A

Errors (change in the sequence of bases) created randomly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
107
Q

Biological Molecules:
What is the Genetic code? What are 3 features about it?

A

DNA coding for an amino acid.
Triplet code - read in threes (codon)
Degenerate - Codons are not overlapping. amino acids can be coded for by many codons
Universal - genetic code is the same for most organisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
108
Q

Biological Molecules:
What is a start codon?

A

Met - Codon that starts of DNA translation/transcription, signalling the start of a gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
109
Q

Biological Molecules:
Put the order of Protein synthesis

A

Replication, Transcription, Translation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
110
Q

Biological Molecules:
What is the difference between coding and template strands

A

The strand we want to copy is called the coding strand, The template strand is the one we transcribe

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
111
Q

Biological Molecules:
What are the 4 bases of RNA

A

Adenosine, Uracil, cytosine, Guanine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
112
Q

Biological Molecules:
Explain DNA transcription

A

Free RNA nucleotides pair with complementary bases on the template strand. Phosphodiester bonds form on the RNA nucleotides by the enzyme RNA polymerase. mRNA is formed, which is an exact copy of the Coding strand and complementary to the template strand, but with Uracil, instead of Thymine. MRNA detaches from the DNA, and leaves the nucleus through nuclear pores. Double Helix reforms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
113
Q

Nucleotides:
What is ribosomes split into, what does it contain

A

Small and large subunit, contains ribosomal RNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
114
Q

Nucleotides:
What is the anticodon on tRNA. What does tRNA do?

A

Anticodon is complementary to mRNA strand. tRNA brings over amino acid, corresponding to that codon

115
Q

Nucleotides:
Explain DNA translation

A

mRNA bonds to small subunit of ribosome, at the start codon. tRNA with complimentary anticodon then binds to the mRNA, only two tRNA can be bound at the same time. Peptide bonds are created between amino acids, catalysed by an enzyme. Ribosome moved down mRNA chain, until it reaches a stop codon, where the primary structure is released. The protein then folds into secondary and tertiary structures

116
Q

Nucleotides:
What happens to proteins after translation

A

Protein moves to Golgi apparatus, to be modified

117
Q

Plasma Membrane:
What does the cell surface membrane do?

A

Acts as a barrier, controls movement in and out of cell

118
Q

Plasma Membrane:
What is compartmentaillsation?

A

formation of separate membrane bound areas in a cell,

119
Q

Plasma Membrane:
What can compartmentalisation be used for?

A

incompatible reactions, so allows for specific conditions of the reactions

120
Q

Plasma Membrane:
What is a phospholipid

A

Hydrophilic phosphate head, hydrophobic fatty acid tails

121
Q

Plasma Membrane:
What is the phospholipid bilayer, draw it

A

2 phospholipids, Phosphate heads face outwards, tails point inwards

122
Q

Plasma Membrane:
What are the properties of phospholipids that makes it suited to be in the membrane

A

cells exist in aqueous environments, and are also aqueous, , heads can interact with water

123
Q

Plasma Membrane:
Why is the phospholipid bilayer a theory

A

Membrane is seen as two black lines during electron microscopy

124
Q

Plasma Membrane:
What is the fluid mosaic model?

A

Shows the components of a plasma membrane

125
Q

Plasma Membrane:
Compare intrinsic and extrinsic proteins

A

Intrinsic - embedded through BOTH layers of phospholipids
Extrinsic - proteins that are present on only one side of bilayer, some can move between layers

126
Q

Plasma Membrane:
What are channel proteins?

A

Intrinsic protein, with hydrophobic channel that allows for diffusion of polar molecules

127
Q

Plasma Membrane:
What are carrier proteins?

A

Intrinsic proteins that are part of active transport, they change shape

128
Q

Plasma Membrane:
What are glycoproteins

A

Intrinsic proteins, that have a carbohydrate chan. Play a role in cell adhesion (two cells join to form a junction), and receptors in cell signalling (chemical binds to receptor, causing a response)

129
Q

Plasma Membrane:
What are glycolipids

A

lipid with a carbohydrate tail attached, act as cell markers, so a cell can be recognised

130
Q

Plasma Membrane:
What is cholesterol

A

lipid with a hydrophilic end and hydrophobic end, regulates the fluidity of the membrane, adding stability

131
Q

Plasma Membrane:
How does temperature impact membrane structure?

A

temperature is increased, so phospholipids move more, making the membrane loose it’s structure, so molecules can pass easier

if temp gets too high, eventually breaking down Carrier and channel proteins will denature, decreasing permeability

132
Q

Plasma Membrane:
How does solvents impact membrane structure?

A

Organic solvents (less polar then water) will dissolve membranes. making it more fluid/permeable
Pure alcohol will destroy cells, non-polar alcohol disrupts the membrane, making it more fluid/permeable

133
Q

Plasma Membrane:
What is diffusion?

A

Net, passive movement of particles from a high concentration to a low concentration. until there is an equilibrium

134
Q

Plasma Membrane:
What are the factors effecting the rate of diffusion?

A

Temperature - higher temp = faster diffusion (particles have high kinetic energy)
Concentration difference. (greater difference the faster the rate of diffusion

135
Q

Plasma Membrane:
What is simple diffusion

A

Absence of a barrier or membrane

136
Q

Plasma Membrane:
What molecules can diffuse across a partially permeable membrane? Why?

A

non polar molecules (no charges)
Hydrophobic tails repels substances with positive or negative charges
Small polar molecules can pass through easier then large ones

137
Q

Plasma Membrane:
What is the rate of diffusion across a membrane affected by?

A

Surface area - larger exchange surface = higher rate of diffusion
Thickness of membrane - thinner exchange surface = higher rate of diffusion

138
Q

Plasma Membrane:
What is facilitated diffusion? What does this allow for?

A

Diffusion with involve carrier proteins (without the need for energy) or channel proteins. Allows for movement of polar molecules and ions

139
Q

Plasma Membrane:
What is facilitated diffusion impacted by?

A

Temperature, Concentration gradient, membrane surface area and thickness, and number of protein channels
More protein channels = higher rate

140
Q

Plasma Membrane:
What is active transport

A

A selective, active movement of molecules from a low concentration to a high concentration. Requiring energy

141
Q

Plasma Membrane:
Explain active transport

A

Molecule binds to the channel of the carrier protein. ATP binds to the carrier protein and gets hydrolysed. This causes the carrier protein to change shape, opening to the inside of the cell. ADP and P group bond to form ATP, the carrier

142
Q

Plasma Membrane:
What is bulk transport

A

Active transport of large molecules are transported in and out of a cell. Like enzymes, hormones and bacteria

143
Q

Plasma Membrane:
What is endocytosis

A

Bulk transport into cells

144
Q

Plasma Membrane:
What is phagocytosis?
What is pinocytosis?

A

Phagocytosis - Endocytosis of solids
Pinocytosis - Endocytosis of liquids

145
Q

Plasma Membrane:
Explain endocytosis

A

Cell surface membrane bends inwards as it comes into contact with material. Membrane enfolds the material, forming a vesicle, Which pinches off and moves into the cytoplasm

146
Q

Plasma Membrane:
What in endocytosis

A

Vesicles (formed by the Golgi apparatus) move towards and forms with the cell surface membrane, contents of the vesicle are released to the outside of the cell

147
Q

Plasma Membrane:
Why does Bulk transport require energy?

A

ATP is needed for the movment of vesicles along the cytoskeleton, changing shape of cells to engulf materials, fusion of cell membranes as vesicle or as they meet the cell surface membrane

148
Q

Plasma Membrane:
What is osmosis

A

the passive diffusion of water across a partially permeable membrane

149
Q

Plasma Membrane:
What is water potential?

A

the pressure exerted by water molecules as they collide with a container or membrane

150
Q

Plasma Membrane:
What is water potential measured in

A

Pascals (Pa) Killa Pascals (KPa) 𝛙

151
Q

Plasma Membrane:
What is pure water measured as. What is other water measured as?

A

0Kpa, all other solutes have a negative water potential (more concentrated, the more negative)

152
Q

Plasma Membrane:
In a closed system, what does the diffusion of water into a solution lead to

A

Hydrostatic pressure

153
Q

Plasma Membrane:
What is the effect on an animal cell if it is placed in a solution that has a higher water potential then the cytoplasm

A

Water moves into the cell, cell may burst (cytolysis)

154
Q

Plasma Membrane:
What happens is an animal cell is placed in a solution that has a lower water potential then the cytoplasm?

A

Cell looses water, causing a shrunken or shrivelled (crenation)

155
Q

Plasma Membrane:
What is the effect on a plant cell if it is placed in a solution that has a higher water potential then the cytoplasm

A

Water enters the cell, increased hydrostatic pressure, pushing the membrane against the rigid cell wall, (pressure is called turgor), the turgor resists entry of further water (turgid)

156
Q

Plasma Membrane:
What happens to a plant cell if it is placed in a solution that has a lower water potential then the cytoplasm?

A

Water is lost, the cytoplasm looses volume, causing the cell surface membrane away from the cell wall (plasmolysed)

157
Q

Cell division:
What is the cell cycle?

A

Sequence of events that take place, resulting in the division of the cell

158
Q

Cell division:
What are the two main phases in the cell cycle

A

Interphase and mitotic phase

159
Q

Cell division:
What is interphase

A

Long periods of growth and normal workings

160
Q

Cell division:
What happens during interphase?

A

DNA is replicated and checked for errors in the nucleus, Protein synthesis occurs in the cytoplasm, Mitochondria grow and divide, (chloroplasts grow and divide), Normal metabolic processes if cells occur

161
Q

Cell division:
What are the three stages of interphase?

A

G1
S
G2

162
Q

Cell division:
What occurs during G1 of interphase

A

Proteins from which organelles are synthesised and produced, organelles replicate, increasing cell size

163
Q

Cell division:
What occurs during S of interphase?

A

DNA is replicated in the nucleus

164
Q

Cell division:
What occurs in G2 of interphase

A

Cell increases in size, energy stores are increased and duplicated, DNA is checked for errors

165
Q

Cell division:
What is the difference between mitosis and cytokinesis

A

Mitosis - nucleus divides
Cytokinesis - cytoplasm divides, two cells are produced

166
Q

Cell division:
What is G0

A

During stage G1 Cell leaves the cycle, either temporarily or permanently

167
Q

Cell division:
Why might a cell enter G0?

A

Differentiation - cell becomes specialised and is no longer able to divide (does not re-enter)
DNA of a cell may be damaged - No longer viable, normal cells can only divide a limited number of times, eventually becoming senescent (does not re-enter)

168
Q

Cell division:
What are checkpoints in the cell cycle

A

Monitor and verify whether the processes have been accurately completed, before the cell can progress

169
Q

Cell division:
Where is the G1 checkpoint? What do this check for? Where does an unsatisfactory cell go?

A

G1 checkpoint - end of G, before entry into S, checks for cell size, nutrients, growth factors, DNA damage
Cell travels to G0 (resting state)

170
Q

Cell division:
Where is the G2 checkpoint? What do this check for? Where does an unsatisfactory cell go?

A

End of G2 phase, before mitotic phase, checks for cell size, DNA replication, DNA damage

If not cell goes to resting state

171
Q

Cell division:
Where is the Spindle assembly (metaphase) checkpoint? What do this check for? Where does an unsatisfactory cell go?

A

During metaphase, all chromosomes should be attached to spindles, Mitosis cannot occur until this checkpoint is passed

172
Q

Cell division:
What enzyme allows the passing of a cell cycle checkpoint? What does this enzyme do?

A

Kinases
Catalyse the addition of a phosphate group to a protein (cyclins), Forming a CDK (cyclin dependent kinase) changing the tertiary structure

173
Q

Cell division:
What is cancer? What is a tumour

A

Uncontrolled division of cells, abnormal mass

174
Q

Cell division:
What is the difference between benign and malignant tumours

A

Benign - Stop growing and do not travel to other locations
Malignant - Does not stop growing, can break off and spread to other areas

175
Q

Cell division:
What can cause tumors?

A

Damage or mutation of genes that encode proteins needed to regulate cell cycle.

Overexpression of cyclin gene, disrupts cell cycle, leading to uncontrolled division

176
Q

Cell division:
Why is mitosis important?

A

Growth, replacement and repair, asexual reproduction

177
Q

Cell division:
What is a chromatid? What is a centromere

A

Chromatid - identical DNA molecules
Centromere - area that joins the chromatids

178
Q

Cell division:
What are the four stages of mitosis?

A

PMAT
Prophase
Metaphase
Anaphase
Teleophase

179
Q

Cell division:
What is Prophase? Draw a diagram

A

Chromosomes condense, Nucleolus disappears and the nuclear membrane begins to break down, Spindle structures at poles of cell formed, centrioles migrate to poles. Spindle fibres attach to centromere and begin to pull them to the centre of the cell

180
Q

Cell division:
What is metaphase. Draw a diagram

A

Chromosomes are moved by spindle fibres, chromosomes line up in the middle of a cell, caused the metaphase plate

181
Q

Cell division:
What is anaphase. Draw a diagram

A

Centromeres divide, chromatids are separated due to the shortening of spindle fibres

182
Q

Cell division:
What is telophase. Draw a diagram

A

Chromatids have reached the poles, and are now called chromosomes, two new sets of chromosomes assemble, nuclear envelope reforms, chromosomes start to uncoil and the nucleolus is formed

183
Q

Cell division:
What is cytokinesis

A

Actual division of cell into two separate cells

184
Q

Cell division:
What is a cleavage furrow?

A

In animal cells, a cleavage furrow forms around the middle of the cell, cell surface membrane is pulled inwards by the cytoskeleton until it is close enough to close enough to fuse

185
Q

Cell division:
What happens in plant cells during cell division?

A

Cell wall prevent formation of a cleavage furrow, Vesicles from the Golgi apparatus assemble and fuse with one another, cell surface membrane divides in two, cell wall forms along cell membrane

186
Q

Cell division:
Compare diploid cells and haploid cells

A

Diploid - two chromosomes of each type (one from each parent)
Haploid - One chromosome of each type (gamete)

187
Q

Cell division:
What is a gamete? What is a Zygote

A

Gamete - Haploid sex cell (sperm or egg)
Zygote - fertilised egg, combination of two gametes

188
Q

Cell division:
How are gametes formed? What division is this?

A

Formed by meiosis, reduction division

189
Q

Cell division:
What are homologus chromosomes

A

matching sets of chromosomes, has the same genes at the same loci

190
Q

Cell division:
What is the loci of genes

A

Position of genes on a chromosome

191
Q

Cell division:
What is an allele

A

Different versions of the same gene. (eg different eye colours)

192
Q

Compare Meiosis and mitosis

A

Mitosis - 2 identical daughter cells
1 division
PMAT
Meiosis - 4 genetically different daughter cells
2 divisions
PMAT PMAT

193
Q

Cell division:
What is the stages in meiosis

A

Prophase I, Metaphase I, Anaphase I, Telophase I, Prophase II, Metaphase II, Anaphase II, Telophase II

194
Q

Cell division:
What happens in Meiosis I

A

First division, each cell only contains one full set of genes, instead of two, cells are haploid

Prophase I, Metaphase I, Anaphase I, Telophase I

195
Q

Cell division:
What happens in Meiosis II

A

Second division, forming 2 new cells, four haploid cells are produced

196
Q

Cell division:
When does crossing over of chromosomes occur, What does this cause

A

Crossing over occurs in Prophase I, this causes genetic variations

197
Q

Cell division:
What happens in Prophase I

A

Chromosomes condense, nuclear envelope disintegrates, nucleolus disappears.
Homologous chromosomes pair up, forming bivalents, chromosomes entangle, causing crossing over

198
Q

Cell division:
What happens in Metaphase I

A

same as mitosis, but
Orientation of each pair of homologous pairs is random, maternal (female parent of parent) or parental (male, parent of parent) chromosomes can end up facing either pole, resulting in independent assortment

199
Q

Cell division:
What happens in Anaphase I

A

Homologous chromosomes are pulled to poles, chromatids remain joined.
Sister chromatids become entangled, break of and re-join, (break is called chiasmata), if exchange occurs, this forms recombinant chromatids (alleles are exchanged). This leads to genetic variation

200
Q

Cell division:
What happens in telophase I, and after telophase I

A

Chromosomes assemble at poles, nuclear membrane reforms, chromosomes uncoil.

After - cytokinesis - reduction in chromosome number, from diploid (two chromatids) to haploid (One chromatid)

201
Q

Cell division:
What happens in Prophase II

A

Chromosomes (two chromatids) condense and become visible, nuclear envelope breaks down, spindle formation begins

202
Q

Cell division:
What happens during Metaphase II

A

Individual chromosomes assemble on the metaphase plate. Due to crossing over, chromatids are no longer identical so there is independent assortment and more genetic variation

203
Q

Cell division:
What happens in Anaphase II

A

Chromatids are pulled apart

204
Q

Cell division:
What happens in Telophase II, What happens after

A

Chromatids assemble at the poles, chromosomes uncoil and and form chromatin, nuclear envelope reform and nucleolus becomes visible

Cytokinesis - divisions of cells form four genetically different haploid daughter cells.

205
Q

Cell division:
Why are the four daughter cells at the end of meiosis genetically diffrent?

A

Independent assortment - Maternal and parental chromosomes face either poles during metaphase
Crossing over - Chromosomes entangle, during Prophase I and anaphase I, During anaphase I, parts of the chromatids break of and re-join (called Chiasmata), these are recombinant chromatids, with genes being exchanged
Mutation - random mutation can cause genetic variation

206
Q

Cell division:
What is specialisation?

A

unspecialised cells become specialised and have different roles

207
Q

Cell division:
How are Erythrocytes (red blood cells) specialised

A

flattened biconcave shape - increases surface area to volume ratios
no nucleus - increases space for haemoglobin, so more oxygen can be carried
Flexible - able to fit through capillaries

208
Q

Cell division:
How are Neutrophils (white blood cells) specialised?

A

Multi-lobed nucleus - easier for them to move through small gaps and get to site of infection
Granular cytoplasm - contain many lysosomes used to attack pathogens

209
Q

Cell division:
How are sperm cells specialised?

A

Flagellum - capable of movement
Contain many mitochondria - supply energy for swimming
Acrosome (head) contains digestive enzymes - digest protective layers around the ovum

210
Q

Cell division:
How are palisade cells specialised?

A

Contain chloroplasts - absorb large amounts of light
Rectangular shaped - closely packed together
Thin cell walls - increase rate of diffusion of CO2
Large vacuole - maintain turgor pressure
Chloroplasts can move in the cytoplasm to absorb more light

211
Q

Cell division:
How are root hair cells specalised?

A

Long extensions - increase surface area, maximising uptake of water and minerals

212
Q

Cell division:
How are guard cells specialised?

A

When guard cells lose water and becomes less swollen they change shape - stomata closes to prevent further water loss

213
Q

Cell division:
What is a tissue?

A

Collection of differentiated cells that have specialised function

214
Q

Cell division:
What are the four main category’s of tissues in animals

A

Nervous - electrical impulses
Epithelial tissues - cover body surfaces (internal and external)
Muscle tissue - adapted to contract
Connective tissue - adapted to hold other tissues together or act as a transport medium

215
Q

Cell division:
What is the squamous epithelium, how is it adapted? One example

A

Flat and Thin - one cell thick, allows for rapid diffusion
Alveoli - needs diffusion of oxygen and carbon dioxide

216
Q

Cell division:
What is the ciliated epithelium , how is it adapted? One example

A

Hair-like structures called cilia
Goblet cells - release mucus to trap unwanted particles
Bronchi - prevent pathogens or bacteria reaching the alveoli

217
Q

Cell division:
What is the cartilage , how is it adapted? One example

A

Contains fibres of of elastin and collagen
Firm and flexible - prevents end of bones rubbing together
Trachea - prevents collapse

218
Q

Cell division:
What is the muscle , how is it adapted? One example

A

Need to contract and relax

219
Q

Cell division:
What is the Epidermis, how is it adapted?

A

layer of cells on surface of plants,
covered by a waxy cuticle - prevents water loss
Stomata - allow for movement of gasses

220
Q

Cell division:
What is the Xylem tissue , how is it adapted?

A

responsible for transport of water and minerals
Composed of dead cells and strengthened by lignin - provides structural support

221
Q

Cell division:
What is the phloem tissue, how is it adapted?

A

Responsible for transport of nutrients
Composed of sieve tube cells

222
Q

Cell division:
What is an organ

A

collection of tissues that are adapted to perform a particular function

223
Q

Cell division:
What is an organ system?

A

composed of many organs working together working together to carry out a function in the body

224
Q

Cell division:
What are three examples of organ systems

A

Digestive system
Cardiovascular system
Gaseous exchange system

225
Q

Cell division:
What are stem cells

A

Undifferentiated cells

226
Q

Cell division:
Stem cells loose the ability to do what once they become specialised

A

Divide, they enter the G0 phase of the cell cycle

227
Q

Cell division:
What is stem cell potency

A

Cells ability to differentiate into different cells

228
Q

Cell division:
What is totipotent?

A

Cell can differentiate into any type of cell.

229
Q

Cell division:
Give an example of a totipotent cell

A

A zygote, or the first 8-16, egg cells from the first few mitotic divisions

230
Q

Cell division:
What is a pluripotent cell

A

Can form all tissue types but not the whole organisms

231
Q

Cell division:
Give an example of a pluripotent cell

A

Early embryos

232
Q

Cell division:
What is a multipotent cell

A

Can only form a range of cells within a certain types of tissue

233
Q

Cell division:
Give an example of a multipotent cell

A

Hematopoietic stem cells in bone marrow, produce various types of blood cell

234
Q

Cell division:
Why is it important that cells differentiate?

A

They can become adapted to a specific role, and become more efficient

235
Q

Cell division:
Why is it important that red blood cells be replaced? How many are made per day

A

short lifespan - around 120 days
Around 3 billion per kilogram per day

236
Q

Cell division:
Why is it important white blood cells are replaced. How many are made per hour, why might this increase?

A

Short life span - 6 hours. Produce 1.6 billion per hour, increases during infections

237
Q

Cell division:
What are two sources of Animal stem cells

A

Embryonic stem cells - very early stage = totipotent, After 7 days, a blastocyst has formed = pluripotent
Adult stem cells - found in specific areas, multipotent

238
Q

Cell division:
Where are plant stem cells found, what type of stem cells are these?

A

Meristem tissue - wherever growth occurs in plants (roots and shoots)
Between phloem and xylem tissues, these are pluripotent

239
Q

Cell division:
What could stem cells be used for?

A

Heart disease, type 1 diabetes, Parkinson’s disease, Alzheimer’s disease, macular degeneration, birth defects, spinal injuries, burns, drug trials, development biology

240
Q

Cell division:
How are embryonic stem cells harvested

A

Left over embryos from IVF

241
Q

Cell division:
Why are embryonic stem cells better then adult stem cells

A

Pluripotent, so can differentiate into any stem cell

242
Q

Cell division:
Give both sides of embryonic stem cells

A

For - can help cure life altering diseases, like Alzheimer’s and type 1 diabetes
Against - involves destruction of ‘possible life’.

243
Q

Cell division:
What are the medical uses of plant stem cells

A

Medical drugs can be created from stem cells, for cheap

244
Q

Enzymes:
What are enzymes

A

Globular proteins that are biological catalysts, that interact with substrates

245
Q

Enzymes:
What are the chemical reactions for growth called. What are the chemical reactions for breaking down called?

A

Building up - Anabolic
Breaking down - Catabolic

246
Q

Enzymes:
What is metabolism

A

Sum of all the different chemical reactions happening in the cell

247
Q

Enzymes:
What is a Vmax

A

Enzymes can only increase the rate of reaction up to a certain point

248
Q

Enzymes:
What conditions effect enzyme action

A

Temperature, pressure, pH, concentration (of substrate and enzyme)

249
Q

Enzymes:
What happens to enzyme action when temperature and pressure increase

A

molecules have higher kinetic energy, resulting in more frequent successful collisions, increasing rate of reaction

250
Q

Enzymes:
What is the specificity of an enzyme

A

An enzyme can only catalyse one reaction

251
Q

Enzymes:
What is the activation energy of a reaction

A

Energy needed to be supplied for a reaction to start

252
Q

Enzymes:
What do enzymes do in terms of the activation energy

A

Enzymes help molecules collide successfully, reducing activation energy

253
Q

Enzymes:
Explain the lock and key hypothesis

A

Only a specific substrate can lock into the active site of the enzyme. When the substrate binds to an enzyme, The R groups interact, holding the substrate in place, a enzyme substrate complex is formed. Substrate reacts, forming an enzyme-product complex, products are released, enzyme remains unchanged.

254
Q

Enzymes:
Explain the induced fit-hypothesis

A

Enzyme changes shape slightly when substrate enters,

255
Q

Enzymes:
Why did the induced fit hypothesis become created

A

Initial interaction between enzymes and substrate is weak, however, this changes the enzyme’s tertiary structure, strengthening the binding and lowering activation energy

256
Q

Enzymes:
What are intracellular enzymes. What are extracellular enzymes

A

Intra - Enzymes in the cell.

Extra - Enzymes that work outside the cell, break down large molecules, so that they can enter the cell

257
Q

Enzymes:
Explain starch breaking down

A

Amylase breaks starch into maltose.
Maltose is broken down into glucose by maltase

258
Q

Enzymes:
Where is Amylase produced

A

Amylase is produced in salivary glands and pancreas, and released in pancreatic juice and small intestine

259
Q

Enzymes:
Where is maltase present

A

Small intestine

260
Q

Enzymes:
How does temperature impact enzyme action?

A

Increasing temperature increases the kinetic energy of particles, so collide successfully more frequently

261
Q

Enzymes:
What is the temperature coefficient (Q10)

A

How much the Rate of reaction increases with a 10oc rise

262
Q

Enzymes:
What does denatured means

A

Enzyme’s active site changes shape, meaning it is no longer complementary to the substrate

263
Q

Enzymes:
What happens if temperature increases too much

A

Enzyme becomes denatured, Temperature coefficient does not apply any more, as the enzymes has become denatured

264
Q

Enzymes:
What is the optimum temperature

A

temperature at which enzyme activity is at it’s highest

265
Q

Enzymes:
What adaptations have enzymes adapted if they are in temperature extremes

A

Cold - more flexible structure
Warm - les flexible structure (more bonds)

266
Q

Enzymes:
What is the impact of pH on enzyme action

A

pH above or below the optimum pH causes the active site to change, but if the pH returns, then active site resumes normal shape - renaturation
Significant pH change causes irreversible denature

267
Q

Enzymes:
What is the impact of substrate and enzyme concentration on enzyme action

A

Higher concentration of either increases rate of reaction
Substrate - higher collision rate with enzyme
Enzyme - increases available active sites
RoR increases to maximum Vmax - all active sites are occupied

268
Q

Enzymes:
What is the limiting factor

A

Factor that prevents more reactions occurring

269
Q

Enzymes:
Why is it important to control enzyme action

A

So that reactions do not occur too fast, reactions can be multi-step

270
Q

Enzymes:
how can enzymes be activated?

A

Cofactors

271
Q

Enzymes:
How can enzymes be inhibited?

A

inhibitors

272
Q

Enzymes:
What are the two types of inhibitors

A

Competitive, non-competitive

273
Q

Enzymes:
What are competitive inhibitors

A

Molecule with similar shape to the substrate fit into active site, blocking the substrate from entering the active site, so enzyme cannot carry out it’s function, slowing down rate of reaction

274
Q

Enzymes:
What are the impacts of competitive inhibitors

A

Reduces rate of reaction, without changing the Vmax, if substrate concentration is increased, there will be much more substrate than inhibitors, so Vmax can be reached

275
Q

Enzymes:
Give an example of a competitive inhibitors

A

Statins - CI of an enzyme used to synthesize cholesterol
Aspirin - Inhibits the active sites of COX enzymes preventing chemicals for pain/fevers

276
Q

Enzymes:
What are non competitive inhibitors?

A

Inhibitor binds to an enzyme at a location other then the active site, causing the tertiary structure of an enzyme, resulting in the active site no longer having a complementary shape, so the enzyme cannot carry out it’s function, they can be reversible or irreversible

277
Q

Enzymes:
What is the effect of non-competitive inhibitors on enzyme activity

A

Increasing the concentration of an inhibitor decreases rate of reaction, increasing enzyme or subsrate concentration will not overcome inhibitor

278
Q

Enzymes:
What is an example of an irreversible non-competitive inhibitor

A

Organophosphates - insecticides, inhibit acetyl cholinesterase, (enzyme necessary for nerve impulses)

279
Q

Enzymes:
What is end product inhibition.

A

Enzyme inhibition occurs when the product of a reaction acts as an inhibitor, negative feedback

280
Q

Enzymes:
What are cofactors

A

non protein ‘helper’ components

281
Q

Enzymes:
What are inorganic cofactors

A

Obtained via the diet, minerals, vitamins

282
Q

Enzymes:
What are prosthetic groups

A

Cofactors and are required by some enzymes, tightly bound to the enzyme, forming a permanent feature

283
Q

Enzymes:
What is precursor activation

A

Need to undergo a change in shape to be activated, through the addition of a cofactor or coenzyme

284
Q

Enzymes:

A

BIOLOGY OCR A (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions