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Biology > Foundations In Biology > Flashcards

Foundations In Biology Flashcards

1
Q

Outline how a student could prepare a temporary mount of tissue for a light microscope

A

Obtain thin section of tissue
Place plant tissue in drop of water
Stain tissue on a slide
As coverslip using mounted needle

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2
Q

Describe how light microscopes work

A

Lenses focus rays of light and magnify
Different structures absorb different amounts of light
Reflected light is transmitted to the observer via objective lens and eyepiece

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3
Q

Describe how a transmission electron microscope works

A

Beam of electrons through specimen
More dense structures appear darker
Focus image onto flourescent screen or photographic plate using magnetic lenses

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4
Q

Describe how a scanning electron microscope works

A

Focus beam of electrons onto surface using electromagnetic lenses
Reflected electrons hit a collecting device and are amplified to produce an image on a photographic plate

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5
Q

How a laser scanning confocal microscope works

A

Focus laser beam using objective lenses
Pluorophores in the sample emit photons
Photomuliplier tube amplifies the signal onto a detector an image is produced pixel by pixel

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6
Q

Calculate actual size

A

Actual size=image size/ magnification

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7
Q

Define magnification and resolution

A

Magnification=factor by which the image is larger than the actual specimen
Resolution=smallest separation distance at which 2 separate structures can be distinguished from each other

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8
Q

Why do samples need to be stained

A

Facilitates absorption of wavelengths of light to produce image and to differentiate structures

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9
Q

Mag. And res of a light microscope

A

Mag=×2000
Res=200nm

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10
Q

Mag and res TEM

A

Mag=×500000
Res=0.5nm

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11
Q

Mag and res SEM

A

Mag=×500000
Res=3-10nm

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12
Q

How to use an eyepiece graticule and stage micrometer

A

Place micrometer on stage to calibrate eye piece graticule
Count how many graticule divisions are in 100micrometers on the micrometer
Length of 1 eyepiece division=100 micrometers/ number of divisions
Use calibrated values to calculate actual length of structures

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13
Q

7 biologically important properties of water

A

Maximum density at 4°c
High surface tension
Incompressible
Solvent
High specific heat capacity
High latent heat of vaporisation
Cohesion

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14
Q

Why is it good for water to be incompressible

A

Provides turgidity to plant cells
Provides hydrostatic skeleton for some small animals like earthworms

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15
Q

Explain why ice floats on water

A

I’ve is less dense because of hydrogen bonds
Insulates water so aquatic organisms can survive

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16
Q

Why is it good for water to have high surface tension

A

Slows water loss due to transpiration
Some insects can skim across the surface of water

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17
Q

Water as a solvent

A

Dissolves and transports charged particles involved in intra&extracellular reactions

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18
Q

High specific heat capacity and high latent of vaporisation of water

A

Acts as a temperature buffer
Cooling effect when water evaporates from skin

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19
Q

Define monomer and polymer

A

Monomer:smaller units that join together to form larger molecules.
Polymer:formed when monomers join together

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20
Q

What happens in condensation and hydrolysis reactions

A

Condensation: Bond forms and water is produced
Hydrolysis: water is used to break a bond

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21
Q

Properties of alpha glucose

A

Small and water soluble- easily transported in blood stream

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22
Q

What type of bonds between monosaccharides

A

1,4 or 1,6 glycosidic bonds

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23
Q

3 disaccharides

A

Maltose: glucose and glucose
Sucrose:glucose and fructose
Lactose:glucose and galactose

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24
Q

Structure and function of starch

A

Storage polymer of alpha glucose
Insoluble, large
Made from amylose:1,4 glycosidic bonds helix shape and compact
Made from amylopectin: 1,4&1,6 glycosidic bonds branched

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25
Q

Structure and function of glycogen

A

Storage polymer of alpha glucose in animals
1,4 and 1,6 g bonds
Branched
Insoluble
Compact

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26
Q

Structure and function of cellulose

A

Polymer of beta glucose gives rigidity to plant cell walls
1,4 g bonds
Straight chain-unbranched
Alternate glucose molecules rotated 180°
H-bond crosslinks between parallel strands form microfibrils- high tensile strength

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27
Q

How do triglycerides form

A

Condensation reaction between 1 glycerol and 3 fatty acids forming ester bonds

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28
Q

Structure and function of triglycerides

A

High energy: mass ratio= high calorific value (energy storage)
Insoluble hydrocarbon chain= used for waterproofing
Slow conductor of heat= thermal insulation
Less dense than water= buoyancy

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29
Q

Structure and function of phospholipids

A

Glycerol backbone 2 hydrophobic fatty acid tails and 1 hydrophilic polar phosphate head
Forms phospholipid bilayer

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30
Q

General structure of an amino acid

A

COOH group
R variable group
NH2 amine group

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31
Q

How polypeptide form

A

Condensation reaction forms peptide bonds

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32
Q

Primary and secondary protein structure

A

Primary-sequence number and type of amino acids
Secondary- h-bonds form alpha helix and beta pleated sheets

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33
Q

Tertiary protein structure

A

Disulfide bridges
Ionic bonds
Hydrogen bonds
Hydrophobic/phillic interactions

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34
Q

Quaternary protein structure

A

More that one poly peptide chain

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35
Q

Structure and function globular proteins

A

Spherical and compact
Usually water soluble
Involved in metabolic processes e.g amylase, insulin and haemoglobin

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36
Q

Structure and function of fibrous proteins

A

Can form long chains or fibres
Insoluble in water
Structural function

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37
Q

Functions of collagen elastin and keratin

A

Collagen: component of bones cartilage tendons etc
Elastin: elasticity to arteries,skin,lungs,cartilage,ligaments
Keratin: component of hair,nails,hooves,claws,epithelial cells of outer skin layer

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38
Q

Test for proteins

A

Buiret test
Equal volumes of sodium hydroxide to sample
Drops of copper(II) sulfate solution
Mix
Positive result= blue->purple

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39
Q

Test for lipids

A

Dissolve in ethanol
Add equal volume of water and shake
Positive result= milky white emulsion

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40
Q

Test for reducing sugars

A

Add benedicts reagent
Heat in water bath 100°c for 5 mins
Positive result= blue-> orange&brick red precipitate forms

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41
Q

Test for non reducing sugars

A

Hydrolyse non reducing sugars by adding 1cm^3 of HCl heat for 5 mins
Neutralise solution with sodium carbonate solution
Proceed with usual benedicts test

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42
Q

Test for starch

A

Add iodine
Positive = orange->blue black

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43
Q

Measure the concentration of a solution quantitavely

A

Use colorimetry to measure absorbance
Use biosensors

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44
Q

Rf values

A

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

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45
Q

Pentose sugars in DNA &RNA

A

DNA= deoxyribose
RNA=ribose

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46
Q

How polynucleotide strands are formed and broken down

A

Condensation between nucleotides dorm phosphodiester bonds hydrolysis reactions break these bonds
Enzymes catalyse these reactions

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47
Q

Structure of DNA

A

Double helix of 2 polynucleotide strands H-bonds between complementary base pairs (AT and CG) in strands that run antiparallel

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48
Q

Purine bases

A

Adenine and guanine
Two ring molecules

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49
Q

Primitive bases

A

Thymine cytosine uracil
One ring molecules

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50
Q

Complementary base pairs

A

DNA 2 h bonds AT
RNA-2 h bonds AU
both- 3 h bonds GC

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51
Q

What is semiconservative replication

A

Strands from original DNA act as templates

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52
Q

Role of DNA helicase

A

Breaks h bonds between base pairs to form 2 single strands

53
Q

How is a new strand formed in semiconservative replication

A

Free nucleotides attach to exposed bases
DNA polymerase joins adjacent nucleotides in a 5’->3’ direction to form phosphodiester bonds
H bonds reform

54
Q

Features of the genetic code

A

Non-overlapping
Degenerate
Universal

55
Q

How does a gene determine the sequence of amino acids

A

Consists of base triplets that code for specific amino acids

56
Q

Transcription

A

Produces mRNA
Occurs in nucleus

57
Q

Process of transcription

A

RNA polymerase binds to promoter region on gene
DNA uncoils so exposed bases
Free nucleotides attach to complementary bases
RNA polymerase joins adjacent nucleotides

58
Q

After transcription

A

RNA polymerase detaches
H bonds reform and DNA rewinds
Splicing removes introns from pre-mRNA in eukaryotic cells
mRNA moves out of nucleus via nuclear pore &attaches to ribosome

59
Q

Translation

A

Produces proteins
Occurs on ribosomes

60
Q

Process of translation

A

Ribosome moves along RNA until start codon
tRNA anticodon attaches to complementary bases on mRNA
Condensation reactions between between AA on tRNA form peptide bonds requires energy
Process continues to form polypeptide chain until stop codon

61
Q

Structure of ATP&ADP

A

Nucleotide derivative of adenine
ATP has 3 inorganic phosphate groups
ADP has 2

62
Q

What is a mutation

A

An alteration to the DNA base sequence

63
Q

What are enzymes

A

Biological catalysts

64
Q

Example of an enzyme that catalyses an intracellular reaction

A

Catalase -decomposition of hydrogen peroxide into water and oxygen

65
Q

Examples of enzymes that catalyse extracellular reactions

A

Amylase and trypsin

66
Q

Induced fit model

A

Conformational change enables ES complexes to form, puts strain on substrate bonds , lowering activation energy

67
Q

Lock and key model

A

Complementary to 1 substrate formation of ES complex lowers the activation energy

68
Q

5 factors that affect the rate of enzyme controlled reactions

A

Enzyme concentration
Substrate concentration
Inhibitor concentration
pH
Temperature

69
Q

Substrate concentration

A

Rate increases proportionally to substrate concentration until no more enzymes left

70
Q

Enzyme concentration

A

Rate increases proportionally to enzyme concentration until no more substrate

71
Q

Temperature on rate of enzyme action

A

Increases ans kinetic energy increases until bonds start to break and it is denatured

72
Q

Temperature coefficient

A

Q10 measures change in rate of reaction per 10°c temperature increase
Q10= rate2/ rate 1

73
Q

pH rate of enzyme action

A

Outside range protons/ OH- ions interfere with bonds

74
Q

Competitive inhibitors

A

Bind to active site (similar to substrate) temporarily prevent ES complexes forming , increasing substrate concentration decreases their affect

75
Q

Non-competitive inhibitors

A

Bind elsewhere on enzyme trigger change in active site shape
Substrate concentration has no impact

76
Q

End product inhibition

A

One of the products in a reaction acts as an inhibitor for an enzyme in the pathway preventing further formation of products

77
Q

Metabolic poison

A

Damages cells by interfering with metabolic reactions , usually an inhibitor

78
Q

Examples of metabolic poisons

A

Cyanide
Malonate
Arsenic

79
Q

Inactive precursors in metabolic pathways

A

To prevent damage to cells
One part of the precursor acts as an inhibitor

80
Q

Cofactors

A

Non-protein compounds required for enzyme activity

81
Q

coenzymes

A

Do not bind permanently, often transport molecules or electrons between enzymes

82
Q

Inorganic cofactors

A

Facilitate temporary binding between substrate and enzyme oftem metal ions
Eg. Cl- is the cofactor for amylase

83
Q

Prosthetic groups

A

Tightly bound cofactor act as a permanent part of enzymes binding site e.g. zn2+ for carbonic anhydrase

84
Q

Fluid mosaic model

A

Phospholipid bilayer in which individual phospholipids can move membrane has flexible shape extrinsic and intrinsic proteins are embedded

84
Q

Fluid mosaic model

A

Phospholipid bilayer in which individual phospholipids can move membrane has flexible shape extrinsic and intrinsic proteins are embedded

85
Q

Role of cholesterol &glycolipids in membranes

A

Cholesterol: steroid molecule in some plasma membranes connect phospholipids and reduces fluidity to make bilayer more stable
Glycolipids: cell signalling and recognition

86
Q

Function of extrinsic proteins in membranes

A

Binding sites /receptors
Antigens
Bind cells together
Involved in cell signalling

87
Q

Function of intrinsic transmembrane proteins in membranes

A

Electron carriers, Channel proteins ,carrier proteins

88
Q

Function of membranes inside cells

A

Internal transport system, selectively permeable to regulate movement into/out of organelles
Provide a reaction surface
Isolate organelles from cytoplasm for specific metabolic reactions

89
Q

Function of the cell surface membrane

A

Isolates cytoplasm from extracellular environment
Selectively permeable regulate transport of substances
Involved in cell signalling / recognition

90
Q

3 factors that effect membrane permeability

A

Temperature
pH
Solvent

91
Q

How colorimetry can investigate membrane permeability

A

Plant tissue with soluble pigment in vacuole. Tonoplast and cell surface membrane disrupted = more permeability = pigment dissolves into solution
Select colorimeter filter with complementary colour
Use water to set colorimeter to 0
Measure absorbance/ transmission
High absorbance= more pigment

92
Q

Osmosis

A

Water diffuses across semi permeable membranes from an area of high water potential to an area of low water potential

93
Q

What is water potential

A

Pressure created by water molecules measured in kPa
Pure water =0
More solute = more negative

94
Q

Osmosis affect plant and animal cells

A

Into:
Plant- turgid animal-lysis
Out:
Plant-flaccid, animal- crenation

95
Q

Simple diffusion

A

Passive process- no energy
Net movement of small lipid soluble molecules from area of high conc to low conc

96
Q

Facilitated diffusion

A

Passive process
Specific channel or carrier proteins with complementary binding sites transport large/ polar molecules/ ions down a concentration gradient

97
Q

Explain how channel and carrier proteins work

A

Channel: hydrophilic channels bind to specific ions one side closes and the other opens
Carrier: binds to complementary molecule = conformational change releases molecules on other side

98
Q

Active transport

A

Active process ATP hydrolysis releases phosphate group that binds to a carrier protein causing it to change shape
Specific carrier proteins transports molecules/ions from an area of low conc to an area of high conc

99
Q

Exocytosis and endocytosis

A

Active process
Bulk transport and transporting large particles
Vesicles fuse with cell surface phospholipid membrane

100
Q

5 factors affecting rate of diffusion

A

Temperature
Diffusion distance
Surface area
Size of molecule
Difference in concentration

101
Q

The cell cycle

A

Regulated cycle of division with intermediate growth periods
Interphase
Mitosis/meiosis
Cytokinesis

102
Q

Interphase

A

G1: cell synthesises proteins for replication & cell size doubles
S: DNA replicates
G2: organelles divide

103
Q

Purpose of mitosis

A

Produces 2 genetically identical daughter cells for
Growth
Cell replacement/ tissue paper
Asexual reproduction

104
Q

Stages of mitosis

A

Propose
Metaphase
Anaphase
Telophase

105
Q

Prophase

A

Chromosomes condense
Centrioles move to opposite poles and spindle forms
Nuclear envelope and nucleuolus breakdown

106
Q

Metaphase

A

Sister chromatids line up at the cell equator attached to the spindle by their centromeres

107
Q

Anaphase

A

Requires energy
Chromatids separate and are pulled to opposite poles of cell

108
Q

Telophase

A

Chromosomes decondence
New nuclear envelope reforms

109
Q

Cytokinesis

A

Cell membrane cleavage furrow forms
Contractile division of cytoplasm

110
Q

Cell cycle regulated

A

Checkpoints regulated by by cell-signalling proteins ensure damaged cells do not progress to next stage of cycle
Cyclin-dependent kinase enzymes phosphorylate proteins that initiate next phase of reactions

111
Q

What happens at each checkpoint

A

Between G1 and S cell checks for DNA damage
Between G2 and M cell checks chromosome replication
At metaphase checkpoint cell checks that sister chromatids have attached to spindle correctly

112
Q

Meiosis

A

A form of cell division that produces four genetically different haploid cells with half the number of chromosomes found in the parent cell known as gametes

113
Q

What happens during meiosis I

A

Homologous chromosomes pair to form bivalents
Crossing over Occurs at chiasmata
Cell divides into two homologous chromosomes separate randomly each cell contains either maternal or paternal copy

114
Q

Homologous chromosomes

A

Pair of chromosomes with genes at the same locus 1 maternal and 1 paternal some alleles may be same while others are different

115
Q

Meiosis II

A

Independent segregation of sister chromatids
Each cell divides again producing 4 haploid cells

115
Q

Meiosis II

A

Independent segregation of sister chromatids
Each cell divides again producing 4 haploid cells

116
Q

How does meiosis produce genetic variation

A

Crossing over during meiosis I
Independent assortment of homologous chromosomes &sister chromatids
Result in a new combination of alleles

117
Q

How do cells become specialised

A

Some genes are expressed while others are silenced . Cells produce proteins that determine their structure and function

118
Q

What is a transcription factor

A

A protein that controls the transcription of genes so only certain parts of the DNA are expressed

119
Q

How do transcription factors work

A

Move from the cytoplasm into nucleus
Bind to promoter region upstream of target gene
Makes it easier or more difficult for RNA polymerase to bind to gene this increases or decreases rate of transcription

120
Q

Stem cells

A

Undifferentiated cells that can divide indefinitely and turn into other specific cell types

121
Q

4 types of stem cell

A

Totipotent-can develop into any cell type including the placenta and embryo
Pluripotent- any cell except placenta and embryo
Multipotent- only develop into a few different types of cell
Unipotent- only develop into one type of cell

122
Q

Uses of stem cells

A

Repair damaged tissue
Drug testing
Treating neurological diseases
Researching developmental biology

123
Q

2 types of specialised cells

A

Erythrocytes- biconcave,no nucleus, haemoglobin
Leucocytes-lymphocytes,eosinophil,neutrophils,monocytes

124
Q

Structure of squamous and ciliated epithelia

A

Squamous: smooth layer fixed in place by basement membrane
Ciliated: made or ciliated epithelial cells

125
Q

Meristems

A

Totipotent undifferentiated plant cells that can develop into various types of plant cell including xylem vessels and phloem sieve tubes

126
Q

Structure of phloem tissue

A

Sieve tube elements - form a tube
Companion cells - involved in atp production
Plasmodesmata- gaps where cytoplasm links

Biology (6 decks)

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