BIOSCI 101 Short Answers Flashcards
(162 cards)
1
Q
What are the 3 Parameters of Magnification?
A
Magnification, Resolution, Contrast.
2
Q
What is a Light Microscope used for?
A
To visualise cells and large subnuclear organelles.
3
Q
What is an Electron Microscope used for?
A
Electron beam sees through specimen or onto its surface.
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
5
Q
What do Plant Cells have that Animal Cells don’t?
A
Cellulose cell wall, central vacuole, chloroplasts.
6
Q
What are the 2 Key Features of a Mitochondria?
A
Respiratory enzymes in inner membrane/matrix, contain own DNA/ribosomes.
7
Q
What are the 2 Key Features of a Chloroplast?
A
Bound by outer and inner membrane, has thylakoids.
8
Q
What are the 3 Functions of the Cytoskeleton?
A
Maintains cell shape, facilitates cell movement and movement of cell components.
9
Q
What are the 3 Types of Cytoskeletal Filaments?
A
Microtubules, microfilaments, intermediate filaments.
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.
11
Q
What is the Function of Intermediate Filaments?
A
Anchors.
12
Q
What is the Function of Microtubules?
A
Road network for organelles.
13
Q
What is the order of Cell Fractionation?
A
Tissue cells, homogenisation, homogenate, centrifugation.
14
Q
What is the Purpose of Cell Fractionation?
A
Isolates cell components based on size and density.
15
Q
How is Centrifuge Speed related to Visible Components?
A
Slow speeds = Larger organelles.
16
Q
How are Polymers Assembled and Degraded?
A
Assembly (dehydration) and degradation (hydrolysis).
17
Q
Why are Lipids Insoluble?
A
Non-polar hydrocarbon chains.
18
Q
What is the Difference between Saturated and Unsaturated Fats?
A
Saturated - solid at room temp.
Unsaturated - liquid at room temp.
19
Q
What are the 3 Functions of Polysaccharides?
A
Energy/fuel, structural support, carbs can be added to improve other functions.
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.
21
Q
What are Mitochondria?
A
Site of cellular respiration where oxygen and food are combined to make energy (ATP).
22
Q
What is the Chemical Composition of Cells?
A
50%C, 10%N, 15%H, 20%O, 5% other.
23
Q
What are the 3 Types of Polysaccharides?
A
Mono (1), Di (2), Poly (many).
24
Q
How are Saccharides Stored in Plants?
A
Starch: granules in plastids, glucose released by hydrolysis.
25
How are Saccharides Stored in Animals?
Glycogen: in liver/muscle cells, glucose released by hydrolysis.
26
How can Lipids be Identified?
Long hydrocarbon chain, glycerol group, only contain H,C,O.
27
How can Proteins be Identified?
Contains C,H,O,N, contains NH2 group and an acid group.
28
How can Saccharides be Identified?
Only contains H,C,O, 1C:2H:1O ratio, arranged as a ring.
29
Describe the Phospholipid Bilayer.
7-8nm thick, made of hydrophilic head and hydrophobic tail.
30
How Fluid are Phospholipids?
Lateral movement happens 10 million times a second.
31
Which Experiment proved Cell Fusion was Viable?
Mouse cell + human cell, hybrid cell, mixed proteins in 1 hour.
32
What are the 6 Functions of Membrane Proteins?
Enzymatic activity, signal transduction, cell-cell recognition, attachment to cytoskeleton and ECM, intercellular joining, transport.
33
What are some Examples of Active and Passive Transport?
Passive - Diffusion, facilitated
| Active - Na/K Pump
34
Describe the Main Components of Active Transport?
Molecules move across membrane against concentration gradient, requires energy.
35
What are the Functions of Transport Proteins?
Provide selectivity, can increase of transport, continuously recycled, rate of transport limited.
36
What are the 3 Types if Endocytosis?
Phagocytosis, pinocytosis, receptor mediated endocytosis.
37
What are Nucleotides Composed?
Phosphate group, sugar/pentose, nitrogenous base.
38
How is Fluidity Impacted?
By saturation - unsaturated = greater fluidity.
39
How is Fluidity Maintained?
By squeezing of cholesterol at v. cold temperatures.
40
What are Integral Proteins?
Inserted into cell membrane associating with hydrophobic region.
41
What are Peripheral Proteins?
Outside of membrane.
42
What are the Functions of a Protein Extension?
Cell communication with outside environment, anchoring.
43
How many Connexins form a Gap Junction?
6.
44
What is the Function of Plasmodesmata?
Allow RNA/small proteins to move between cells.
45
When is Facilitated Diffusion required?
Hydrophylic can't pass hydrophobic layer.
46
What is Selectivity?
Only select proteins can pass through.
47
What is 'Cell Eating'?
Pseudopodium sent out to engulf food particle.
48
What is 'Cell Drinking'?
Gulps of outside molecules.
49
What does 'Receptor Mediated' mean?
Bind to specific molecules.
50
Which Amino Acids are Hydrophobic and Hydrophilic?
Non-polar: Hydrophobic
Polar: Hydrophilic
Electrically: Hydrophilic
51
What is the Function of Peptide Bonds?
Link carboxyl group of one amino acid to amino group of the next.
52
What is RNA Responsible for?
Information in RNA determines amino acid sequence.
53
Where is the Alpha Helix Found?
In the regions of transmembrane proteins that cross the bilayer.
54
Where are Beta Pleated Sheets Found?
In the core of many globular proteins.
55
What are the 2 Functions of Chaperonins?
Assists the folding of proteins, check correct folding has occurred.
56
How does Heat Denature Structures?
Breaks weak bonds.
57
How does pH Denature Structures?
Changes ionisation patterns of R groups.
58
How do Reducing Agents Denature Structures?
Reduce S=S bonds to SH.
59
How do Organic Solvents Denature Structures?
Disturb hydrophobic and hydrophilic interactions.
60
How do Detergents Denature Structures?
Disrupt hydrophobic interactions.
61
What is an Anabolic Reaction?
Energy enters reaction and is stored in molecular products. Large molecules synthesised from small molecules.
62
What is a Catabolic Reaction?
Energy exits reaction and is available for cellular work. Breakdown of large molecules into energy + small molecules.
63
What is Transport Work?
ATP phosphorylates transport proteins.
64
What is Mechanical Work?
ATP binds non-covalently to motor proteins and then is hydrolysed.
65
What is the Function of an Enzyme?
Act as catalysts, lowering Ea and increasing rate of reaction.
66
Are Enzymes ever 'Used Up'?
No - they are not consumed by the reaction.
67
What are Co-Factors?
Non-proteins that help with catalytic activity.
68
How do Temperature and pH impact Enzyme Activity?
They influence secondary, tertiary and quaternary structure.
69
How do Enzymes Regulate Activity?
By controlling when and where certain enzymes are active.
70
How do Enzymes Dance?
They oscillate between active and inactive forms.
71
What is Feedback Inhibition?
Metabolic pathway is switched off by the end product, binding to/inhibiting an enzyme that acts early in the pathway.
72
How does ATP Release Energy?
Hydrolysing ATP cleaves away a P, energy is released and used to drive cellular processes.
73
How is ATP involved in Transport Work?
ATP donates a P group, providing energy for carrier protein to change shape.
74
How is ATP involved in Mechanical Work?
ATP binds to motor protein, energy released stimulates shape change so protein can take 'steps'.
75
What are the 3 Basic Components of Enzymes?
Majority are made of protein and highly selective/specific, catalyse reactions.
76
How does Substrate amount impact ROR?
Increased substrate = increased ROR (dwindling impact until saturation point reached).
77
What are Prosthetic Groups?
Organic or inorganic molecules tightly bound to the protein.
78
What are Coenzymes?
Small organic molecules non-covalently bound to protein.
79
What were Franklin and Williams Responsible for?
1st to generate X-ray diffraction image of DNA (2 strands).
80
Who came up with the Double Helix Structure?
Watson and Crick.
81
What does each Nucleotide consist of?
Nitrogenous base, sugar, phosphate group.
82
What is a Chromosome?
DNA packed together with proteins.
83
What are RNA Molecules?
Single polynucleotide chains.
84
What is the Function of mRNA?
Conveys info from DNA in nucleus to the ribosome.
85
What is the Function of tRNA?
Translator: nucleotide sequence from mRNA into amino acids.
86
What is each tRNA made of?
4 base-paired regions, 3 loops including anticodon, amino acid attachment site.
87
What is the Function of Single-Strand Binding Proteins?
Prevent single-strand binding DNA from re-pairing.
88
What is the Function of Topoisomerase?
Breaks, swivels and rejoins parental DNA ahead of replication fork (removes strain caused by DNA unwinding).
89
What is the Function of Primase?
Synthesises short RNA primers using the parental DNA as template.
90
What is the Function of Telomeres?
Protect ends of chromosomes, prevent loss of genes near ends.
91
What are the Functions of 5' Cap and 3' Poly-A Tail?
May promote export of mRNA from nucleus, protects mRNA from degradation, 5' cap facilitates ribosome attachment.
92
What happens during Splicing?
Introns are cut out and the exons are ligated together to form the mature mRNA molecule.
93
What is a Codon?
Sequence of 3 nucleotides which can be translated into a particular amino acid.
94
What are tRNA Molecules made up of?
Amino acid attachment site, anticodon loop to pair with the mRNA codon.
95
What is Responsible for Attaching the Correct Amino Acid to each tRNA Molecule?
Aminoacyl tRNA synthetase.
96
Where do Ribosomes Bind?
The 5' end of newly transcribed mRNA at the mRNA binding site.
97
What is the Signal Mechanism?
Signal peptides on the newly generated polypeptides can target them to the ER.
98
What is the Genetic Code?
Set of rules which determines how mRNA info is translated into amino acid sequence.
99
What is the Problem associated with the Genetic Code?
There are only 4 nucleotide bases to specify 20 amino acids.
100
What is Wobble?
Where some tRNA molecules only require accurate pairing for first 2 positions, so 3rd can be mismatched.
101
What is a Start Codon?
Initiates translation but also codes for methionine.
102
What are Point Mutations?
Change in a single base pair.
103
What is a Silent Mutation?
Where there is no effect on amino acid sequence.
104
What is a Missense Mutation?
Where an amino acid is changed.
105
What is a Nonsense Mutation?
Creation of a termination codon or premature stop codon.
106
How can DNA be Damaged?
Incorrectly paired or altered nucleotides, chemical changes of DNA bases.
107
How does Gene Expression Differ in Prokaryotes and Eukaryotes?
Prokaryotes involve response to changes in available nutrients, eukaryotes regulate cell differentiation.
108
What is a Mutation?
Can a permanent, inheritable alteration in the DNA sequence.
109
What is a Mammary Cell?
Totipotent - capable of giving rise to any cell type.
110
What is Alt. RNA Splicing?
Different mRNA molecules are produced from the same pre-mRNA.
111
What is Protein Processing?
Many protein functions require a mutation, proteins can be marked for destruction.
112
What happens during Tryptophan Synthesis?
As tryptophan increases, enzyme 1 can be shut down rapidly. Full repression is less rapid.
113
What happens during Negative Gene Regulation?
Repressor protein binds to operator to prevent gene being expressed.
114
What happens to cAMP when Glucose Decreases?
Decrease in glucose = increase in cyclic AMP.
115
What is DNA Methylation?
Condensation of chromatin and reduced transcription.
116
What are Transcription Factors?
Proteins that can initiate and regulate transcription in eukaryotic cells.
117
How long does mRNA take to Degrade?
Typically minutes.
118
Describe Protein Processing?
Protein modification and trafficking is regulated, as well as the length of time a protein functions.
119
How can Non-Coding RNAs Control Gene Expression?
Influencing: chromatin packing, translation, mRNA degradation.
120
Which 2 Levels does Metabolic Control occur at?
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
How do E.Coli adapt to Lactose?
As a new food source by regulating transcription.
122
How do the Numbers of B-Gal increase so quickly?
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
What are the 3 Structural Genes in the Lac Operon?
Lac Z, Lac Y, Lac A.
124
What happens during Negative Regulation?
A repressor protein binds to the operator to prevent the gene being expressed.
125
What happens during Positive Regulation?
A transcription factor or a transcription activator binds to the promoter and enables RNA polymerase to initiate transcription.
126
What does the Lac Repressor do?
Binds to the operator and obstructs the promoter.
127
What does Lactose do when Present?
It acts as an inducer, binds to lac repressor so it changes shape and cannot bind to the operator.
128
Does Bacteria prefer Lactose or Glucose?
Glucose.
129
What happens when Glucose is Low and Lactose is Present?
E.Coli will generate enzymes for lactose breakdown and use lactose as an energy source.
130
How do our Bodies detect Low Glucose Levels?
Without glucose, the signalling molecule (cAMP) accumulates, binding to/activating the activator protein (CAP).
131
What is Positive Gene Regulation?
Where active CAP binds to promoter and facilitates binding of RNA polymerase to promoter, resulting in transcription of the Lac Operon genes.
132
What happens to the Repressor when Lactose is Present?
Repressor is unable to bind to operon.
133
What happens to cAMP when Glucose Increases?
cAMP will fall, so it cannot activate CAP.
134
What happens to the Lac Operon if Glucose is Present?
CAP detaches, RNA polymerase binds less efficiently to promoter, so transcription occurs at a low level.
135
What happens when there is a Mutation in the Structural Genes of the Lac Operon?
A non-functional protein may be produced.
136
What happens when there is a mutation in Lac I?
Transcription is abolished, RNA polymerase binding site may be destroyed, transcription may be permanently turned on.
137
What is Recombinant DNA Technology?
Genes or DNA from 2 different sources are combined in vitro into the same molecule.
138
What are the Two Sections of a Typical Gene?
Promoter and coding region.
139
What is Biotechnology?
The manipulation of organisms or their components to make useful products.
140
What is Genetic Engineering?
The in vitro alteration or recombination of genetic material and the reintroduction of the altered genetic material into a living organism.
141
What do Restriction Enzymes do?
Cut DNA at specific sequences 4-8 bp in length.
142
What are Cloning Vectors?
DNA molecule that can carry foreign DNA.
143
When is a Cell Competent?
Once the cell is ready to take up DNA.
144
What are the 2 types of Selectable Marker?
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
What is DNA Ligase?
The sticky or blunt ends of DNA.
146
What does DNA Ligase do?
Catalyses the formation of covalent bonds that close up the sugar-phosphate backbone.
147
What is Transformation used for?
Introducing plasmid DNA into bacterial cells.
148
What is PCR?
A 3 step process that produces millions of copies of a targeted region of DNA.
149
How long do the D,A,E Cycles take?
D - 10 secs
A - 30 secs
E - 1 min per kilo based pair
150
What does Gel Electrophoresis do?
Separates macromolecules on the basis of their rate of movement though a gel in an electrical field - molecular sieve.
151
What does Rate of Movement in Gel Electrophoresis depend on?
Size, electrical charge, other physical properties.
152
What is the Genome?
The total compliment of DNA that makes up the inherited genetic material of an organism.
153
What is the Function of DNA Sequencing?
Reveals the order of nucleotides along a strand of DNA.
154
How do we Identify Bases?
There is a distinct fluorescent tag for each type of nucleotide.
155
What is Next-Gen Sequencing?
The ability to sequence multiple DNA strands simultaneously.
156
What is Reproduction?
When an entity undergoes division that results in the production of two entities of the same kind.
157
What is the Difference between the Mitotic Phase and Interphase?
Mitotic Phase - division
| Interphase - non-dividing
158
How does Random Fertilisation impact Variation?
Adds to the variation arising from meiosis.
159
What is Complete Dominance?
An allele is dominant when the phenotypic effect is the same in both the heterozygous and homozygous conditions.
160
What is Incomplete/Partial Dominance?
The dominant allele is not fully expressed in heterozygotes. The heterozygote has an intermediate phenotype.
161
What is Co-Dominance?
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
What is an example of Multiple Alleles?
The gene encoding the ABO blood group.
