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Biology > BIOSCI 101 Short Answers > Flashcards

BIOSCI 101 Short Answers Flashcards

1
Q

What are the 3 Parameters of Magnification?

A

Magnification, Resolution, Contrast.

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2
Q

What is a Light Microscope used for?

A

To visualise cells and large subnuclear organelles.

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3
Q

What is an Electron Microscope used for?

A

Electron beam sees through specimen or onto its surface.

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4
Q

What are the 3 Differences between SEM and TEM?

A

SEM - 10nm res, onto surface, 3D images.

TEM - 2nm res, internal structure, through specimen

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5
Q

What do Plant Cells have that Animal Cells don’t?

A

Cellulose cell wall, central vacuole, chloroplasts.

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6
Q

What are the 2 Key Features of a Mitochondria?

A

Respiratory enzymes in inner membrane/matrix, contain own DNA/ribosomes.

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7
Q

What are the 2 Key Features of a Chloroplast?

A

Bound by outer and inner membrane, has thylakoids.

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8
Q

What are the 3 Functions of the Cytoskeleton?

A

Maintains cell shape, facilitates cell movement and movement of cell components.

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9
Q

What are the 3 Types of Cytoskeletal Filaments?

A

Microtubules, microfilaments, intermediate filaments.

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10
Q

Describe the Process that takes place in the ER.

A

Vesicle fuses with golgi to empty proteins, proteins are modified, budding off into vesicles.

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11
Q

What is the Function of Intermediate Filaments?

A

Anchors.

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12
Q

What is the Function of Microtubules?

A

Road network for organelles.

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13
Q

What is the order of Cell Fractionation?

A

Tissue cells, homogenisation, homogenate, centrifugation.

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14
Q

What is the Purpose of Cell Fractionation?

A

Isolates cell components based on size and density.

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15
Q

How is Centrifuge Speed related to Visible Components?

A

Slow speeds = Larger organelles.

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16
Q

How are Polymers Assembled and Degraded?

A

Assembly (dehydration) and degradation (hydrolysis).

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17
Q

Why are Lipids Insoluble?

A

Non-polar hydrocarbon chains.

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18
Q

What is the Difference between Saturated and Unsaturated Fats?

A

Saturated - solid at room temp.

Unsaturated - liquid at room temp.

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19
Q

What are the 3 Functions of Polysaccharides?

A

Energy/fuel, structural support, carbs can be added to improve other functions.

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20
Q

What are the Major Cell Characteristics?

A

Arise from preexisting cells, genetic info as DNA, proteins are synthesised on ribosomes, membrane encloses every cell.

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21
Q

What are Mitochondria?

A

Site of cellular respiration where oxygen and food are combined to make energy (ATP).

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22
Q

What is the Chemical Composition of Cells?

A

50%C, 10%N, 15%H, 20%O, 5% other.

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23
Q

What are the 3 Types of Polysaccharides?

A

Mono (1), Di (2), Poly (many).

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24
Q

How are Saccharides Stored in Plants?

A

Starch: granules in plastids, glucose released by hydrolysis.

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25
Q

How are Saccharides Stored in Animals?

A

Glycogen: in liver/muscle cells, glucose released by hydrolysis.

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26
Q

How can Lipids be Identified?

A

Long hydrocarbon chain, glycerol group, only contain H,C,O.

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27
Q

How can Proteins be Identified?

A

Contains C,H,O,N, contains NH2 group and an acid group.

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28
Q

How can Saccharides be Identified?

A

Only contains H,C,O, 1C:2H:1O ratio, arranged as a ring.

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29
Q

Describe the Phospholipid Bilayer.

A

7-8nm thick, made of hydrophilic head and hydrophobic tail.

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30
Q

How Fluid are Phospholipids?

A

Lateral movement happens 10 million times a second.

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31
Q

Which Experiment proved Cell Fusion was Viable?

A

Mouse cell + human cell, hybrid cell, mixed proteins in 1 hour.

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32
Q

What are the 6 Functions of Membrane Proteins?

A

Enzymatic activity, signal transduction, cell-cell recognition, attachment to cytoskeleton and ECM, intercellular joining, transport.

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33
Q

What are some Examples of Active and Passive Transport?

A

Passive - Diffusion, facilitated

Active - Na/K Pump

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34
Q

Describe the Main Components of Active Transport?

A

Molecules move across membrane against concentration gradient, requires energy.

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35
Q

What are the Functions of Transport Proteins?

A

Provide selectivity, can increase of transport, continuously recycled, rate of transport limited.

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36
Q

What are the 3 Types if Endocytosis?

A

Phagocytosis, pinocytosis, receptor mediated endocytosis.

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37
Q

What are Nucleotides Composed?

A

Phosphate group, sugar/pentose, nitrogenous base.

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38
Q

How is Fluidity Impacted?

A

By saturation - unsaturated = greater fluidity.

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39
Q

How is Fluidity Maintained?

A

By squeezing of cholesterol at v. cold temperatures.

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40
Q

What are Integral Proteins?

A

Inserted into cell membrane associating with hydrophobic region.

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41
Q

What are Peripheral Proteins?

A

Outside of membrane.

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42
Q

What are the Functions of a Protein Extension?

A

Cell communication with outside environment, anchoring.

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43
Q

How many Connexins form a Gap Junction?

A

6.

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44
Q

What is the Function of Plasmodesmata?

A

Allow RNA/small proteins to move between cells.

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45
Q

When is Facilitated Diffusion required?

A

Hydrophylic can’t pass hydrophobic layer.

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46
Q

What is Selectivity?

A

Only select proteins can pass through.

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47
Q

What is ‘Cell Eating’?

A

Pseudopodium sent out to engulf food particle.

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48
Q

What is ‘Cell Drinking’?

A

Gulps of outside molecules.

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49
Q

What does ‘Receptor Mediated’ mean?

A

Bind to specific molecules.

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50
Q

Which Amino Acids are Hydrophobic and Hydrophilic?

A

Non-polar: Hydrophobic
Polar: Hydrophilic
Electrically: Hydrophilic

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51
Q

What is the Function of Peptide Bonds?

A

Link carboxyl group of one amino acid to amino group of the next.

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52
Q

What is RNA Responsible for?

A

Information in RNA determines amino acid sequence.

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53
Q

Where is the Alpha Helix Found?

A

In the regions of transmembrane proteins that cross the bilayer.

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54
Q

Where are Beta Pleated Sheets Found?

A

In the core of many globular proteins.

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55
Q

What are the 2 Functions of Chaperonins?

A

Assists the folding of proteins, check correct folding has occurred.

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56
Q

How does Heat Denature Structures?

A

Breaks weak bonds.

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57
Q

How does pH Denature Structures?

A

Changes ionisation patterns of R groups.

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58
Q

How do Reducing Agents Denature Structures?

A

Reduce S=S bonds to SH.

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59
Q

How do Organic Solvents Denature Structures?

A

Disturb hydrophobic and hydrophilic interactions.

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60
Q

How do Detergents Denature Structures?

A

Disrupt hydrophobic interactions.

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61
Q

What is an Anabolic Reaction?

A

Energy enters reaction and is stored in molecular products. Large molecules synthesised from small molecules.

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62
Q

What is a Catabolic Reaction?

A

Energy exits reaction and is available for cellular work. Breakdown of large molecules into energy + small molecules.

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63
Q

What is Transport Work?

A

ATP phosphorylates transport proteins.

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64
Q

What is Mechanical Work?

A

ATP binds non-covalently to motor proteins and then is hydrolysed.

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65
Q

What is the Function of an Enzyme?

A

Act as catalysts, lowering Ea and increasing rate of reaction.

66
Q

Are Enzymes ever ‘Used Up’?

A

No - they are not consumed by the reaction.

67
Q

What are Co-Factors?

A

Non-proteins that help with catalytic activity.

68
Q

How do Temperature and pH impact Enzyme Activity?

A

They influence secondary, tertiary and quaternary structure.

69
Q

How do Enzymes Regulate Activity?

A

By controlling when and where certain enzymes are active.

70
Q

How do Enzymes Dance?

A

They oscillate between active and inactive forms.

71
Q

What is Feedback Inhibition?

A

Metabolic pathway is switched off by the end product, binding to/inhibiting an enzyme that acts early in the pathway.

72
Q

How does ATP Release Energy?

A

Hydrolysing ATP cleaves away a P, energy is released and used to drive cellular processes.

73
Q

How is ATP involved in Transport Work?

A

ATP donates a P group, providing energy for carrier protein to change shape.

74
Q

How is ATP involved in Mechanical Work?

A

ATP binds to motor protein, energy released stimulates shape change so protein can take ‘steps’.

75
Q

What are the 3 Basic Components of Enzymes?

A

Majority are made of protein and highly selective/specific, catalyse reactions.

76
Q

How does Substrate amount impact ROR?

A

Increased substrate = increased ROR (dwindling impact until saturation point reached).

77
Q

What are Prosthetic Groups?

A

Organic or inorganic molecules tightly bound to the protein.

78
Q

What are Coenzymes?

A

Small organic molecules non-covalently bound to protein.

79
Q

What were Franklin and Williams Responsible for?

A

1st to generate X-ray diffraction image of DNA (2 strands).

80
Q

Who came up with the Double Helix Structure?

A

Watson and Crick.

81
Q

What does each Nucleotide consist of?

A

Nitrogenous base, sugar, phosphate group.

82
Q

What is a Chromosome?

A

DNA packed together with proteins.

83
Q

What are RNA Molecules?

A

Single polynucleotide chains.

84
Q

What is the Function of mRNA?

A

Conveys info from DNA in nucleus to the ribosome.

85
Q

What is the Function of tRNA?

A

Translator: nucleotide sequence from mRNA into amino acids.

86
Q

What is each tRNA made of?

A

4 base-paired regions, 3 loops including anticodon, amino acid attachment site.

87
Q

What is the Function of Single-Strand Binding Proteins?

A

Prevent single-strand binding DNA from re-pairing.

88
Q

What is the Function of Topoisomerase?

A

Breaks, swivels and rejoins parental DNA ahead of replication fork (removes strain caused by DNA unwinding).

89
Q

What is the Function of Primase?

A

Synthesises short RNA primers using the parental DNA as template.

90
Q

What is the Function of Telomeres?

A

Protect ends of chromosomes, prevent loss of genes near ends.

91
Q

What are the Functions of 5’ Cap and 3’ Poly-A Tail?

A

May promote export of mRNA from nucleus, protects mRNA from degradation, 5’ cap facilitates ribosome attachment.

92
Q

What happens during Splicing?

A

Introns are cut out and the exons are ligated together to form the mature mRNA molecule.

93
Q

What is a Codon?

A

Sequence of 3 nucleotides which can be translated into a particular amino acid.

94
Q

What are tRNA Molecules made up of?

A

Amino acid attachment site, anticodon loop to pair with the mRNA codon.

95
Q

What is Responsible for Attaching the Correct Amino Acid to each tRNA Molecule?

A

Aminoacyl tRNA synthetase.

96
Q

Where do Ribosomes Bind?

A

The 5’ end of newly transcribed mRNA at the mRNA binding site.

97
Q

What is the Signal Mechanism?

A

Signal peptides on the newly generated polypeptides can target them to the ER.

98
Q

What is the Genetic Code?

A

Set of rules which determines how mRNA info is translated into amino acid sequence.

99
Q

What is the Problem associated with the Genetic Code?

A

There are only 4 nucleotide bases to specify 20 amino acids.

100
Q

What is Wobble?

A

Where some tRNA molecules only require accurate pairing for first 2 positions, so 3rd can be mismatched.

101
Q

What is a Start Codon?

A

Initiates translation but also codes for methionine.

102
Q

What are Point Mutations?

A

Change in a single base pair.

103
Q

What is a Silent Mutation?

A

Where there is no effect on amino acid sequence.

104
Q

What is a Missense Mutation?

A

Where an amino acid is changed.

105
Q

What is a Nonsense Mutation?

A

Creation of a termination codon or premature stop codon.

106
Q

How can DNA be Damaged?

A

Incorrectly paired or altered nucleotides, chemical changes of DNA bases.

107
Q

How does Gene Expression Differ in Prokaryotes and Eukaryotes?

A

Prokaryotes involve response to changes in available nutrients, eukaryotes regulate cell differentiation.

108
Q

What is a Mutation?

A

Can a permanent, inheritable alteration in the DNA sequence.

109
Q

What is a Mammary Cell?

A

Totipotent - capable of giving rise to any cell type.

110
Q

What is Alt. RNA Splicing?

A

Different mRNA molecules are produced from the same pre-mRNA.

111
Q

What is Protein Processing?

A

Many protein functions require a mutation, proteins can be marked for destruction.

112
Q

What happens during Tryptophan Synthesis?

A

As tryptophan increases, enzyme 1 can be shut down rapidly. Full repression is less rapid.

113
Q

What happens during Negative Gene Regulation?

A

Repressor protein binds to operator to prevent gene being expressed.

114
Q

What happens to cAMP when Glucose Decreases?

A

Decrease in glucose = increase in cyclic AMP.

115
Q

What is DNA Methylation?

A

Condensation of chromatin and reduced transcription.

116
Q

What are Transcription Factors?

A

Proteins that can initiate and regulate transcription in eukaryotic cells.

117
Q

How long does mRNA take to Degrade?

A

Typically minutes.

118
Q

Describe Protein Processing?

A

Protein modification and trafficking is regulated, as well as the length of time a protein functions.

119
Q

How can Non-Coding RNAs Control Gene Expression?

A

Influencing: chromatin packing, translation, mRNA degradation.

120
Q

Which 2 Levels does Metabolic Control occur at?

A
  1. Adjust the catalytic activities of the enzymes already made
  2. Adjust the production of enzyme molecules by regulating expression of the genes encoding enzymes.
121
Q

How do E.Coli adapt to Lactose?

A

As a new food source by regulating transcription.

122
Q

How do the Numbers of B-Gal increase so quickly?

A

Bacterial mRNA only lasts a few minutes, so bacteria can rapidly change pattern of protein synthesis in response to a change in food source.

123
Q

What are the 3 Structural Genes in the Lac Operon?

A

Lac Z, Lac Y, Lac A.

124
Q

What happens during Negative Regulation?

A

A repressor protein binds to the operator to prevent the gene being expressed.

125
Q

What happens during Positive Regulation?

A

A transcription factor or a transcription activator binds to the promoter and enables RNA polymerase to initiate transcription.

126
Q

What does the Lac Repressor do?

A

Binds to the operator and obstructs the promoter.

127
Q

What does Lactose do when Present?

A

It acts as an inducer, binds to lac repressor so it changes shape and cannot bind to the operator.

128
Q

Does Bacteria prefer Lactose or Glucose?

A

Glucose.

129
Q

What happens when Glucose is Low and Lactose is Present?

A

E.Coli will generate enzymes for lactose breakdown and use lactose as an energy source.

130
Q

How do our Bodies detect Low Glucose Levels?

A

Without glucose, the signalling molecule (cAMP) accumulates, binding to/activating the activator protein (CAP).

131
Q

What is Positive Gene Regulation?

A

Where active CAP binds to promoter and facilitates binding of RNA polymerase to promoter, resulting in transcription of the Lac Operon genes.

132
Q

What happens to the Repressor when Lactose is Present?

A

Repressor is unable to bind to operon.

133
Q

What happens to cAMP when Glucose Increases?

A

cAMP will fall, so it cannot activate CAP.

134
Q

What happens to the Lac Operon if Glucose is Present?

A

CAP detaches, RNA polymerase binds less efficiently to promoter, so transcription occurs at a low level.

135
Q

What happens when there is a Mutation in the Structural Genes of the Lac Operon?

A

A non-functional protein may be produced.

136
Q

What happens when there is a mutation in Lac I?

A

Transcription is abolished, RNA polymerase binding site may be destroyed, transcription may be permanently turned on.

137
Q

What is Recombinant DNA Technology?

A

Genes or DNA from 2 different sources are combined in vitro into the same molecule.

138
Q

What are the Two Sections of a Typical Gene?

A

Promoter and coding region.

139
Q

What is Biotechnology?

A

The manipulation of organisms or their components to make useful products.

140
Q

What is Genetic Engineering?

A

The in vitro alteration or recombination of genetic material and the reintroduction of the altered genetic material into a living organism.

141
Q

What do Restriction Enzymes do?

A

Cut DNA at specific sequences 4-8 bp in length.

142
Q

What are Cloning Vectors?

A

DNA molecule that can carry foreign DNA.

143
Q

When is a Cell Competent?

A

Once the cell is ready to take up DNA.

144
Q

What are the 2 types of Selectable Marker?

A
  1. A marker to make sure the bacterium has taken up the plasmid.
  2. A marker to make sure that the plasmid has an insert or foreign gene.
145
Q

What is DNA Ligase?

A

The sticky or blunt ends of DNA.

146
Q

What does DNA Ligase do?

A

Catalyses the formation of covalent bonds that close up the sugar-phosphate backbone.

147
Q

What is Transformation used for?

A

Introducing plasmid DNA into bacterial cells.

148
Q

What is PCR?

A

A 3 step process that produces millions of copies of a targeted region of DNA.

149
Q

How long do the D,A,E Cycles take?

A

D - 10 secs
A - 30 secs
E - 1 min per kilo based pair

150
Q

What does Gel Electrophoresis do?

A

Separates macromolecules on the basis of their rate of movement though a gel in an electrical field - molecular sieve.

151
Q

What does Rate of Movement in Gel Electrophoresis depend on?

A

Size, electrical charge, other physical properties.

152
Q

What is the Genome?

A

The total compliment of DNA that makes up the inherited genetic material of an organism.

153
Q

What is the Function of DNA Sequencing?

A

Reveals the order of nucleotides along a strand of DNA.

154
Q

How do we Identify Bases?

A

There is a distinct fluorescent tag for each type of nucleotide.

155
Q

What is Next-Gen Sequencing?

A

The ability to sequence multiple DNA strands simultaneously.

156
Q

What is Reproduction?

A

When an entity undergoes division that results in the production of two entities of the same kind.

157
Q

What is the Difference between the Mitotic Phase and Interphase?

A

Mitotic Phase - division

Interphase - non-dividing

158
Q

How does Random Fertilisation impact Variation?

A

Adds to the variation arising from meiosis.

159
Q

What is Complete Dominance?

A

An allele is dominant when the phenotypic effect is the same in both the heterozygous and homozygous conditions.

160
Q

What is Incomplete/Partial Dominance?

A

The dominant allele is not fully expressed in heterozygotes. The heterozygote has an intermediate phenotype.

161
Q

What is Co-Dominance?

A

Full expression of both alleles in the heterozygote. In humans that have the AB blood group both proteins are present and detected by immunological tests.

162
Q

What is an example of Multiple Alleles?

A

The gene encoding the ABO blood group.

Biology (15 decks)

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