Exam Revision Flashcards
(106 cards)
1
Q
What is a hypothesis?
A
An explanation based on observations and assumptions that leads to a testable prediction.
2
Q
What is deductive reasoning?
A
Reasoning that flows in the opposite direction - predictions of results that will be found if a particular premise is incorrect.
3
Q
What are polymers?
A
Long chains of covalently joined monomers.
4
Q
What are nucleic acids?
A
Polymers of nucleotides.
5
Q
What are proteins?
A
Polymers of amino acids.
6
Q
What is polymer synthesis?
A
The set of dehydration reactions that removes water and creates a longer polymer.
7
Q
What is polymer hydrolysis?
A
The set of hydrolysis reactions which adds water and breaks the polymer down.
8
Q
What is a nucleotide composed of?
A
A sugar, a base and a phosphate group.
9
Q
Which part of DNA is charged?
A
The phosphate group.
10
Q
What are the pyrimidines?
A
CUT - Cytosine, Uracil and Thymine.
11
Q
What are the purines?
A
Adenine and Guanine.
12
Q
Where is the DNA of a prokaryotic cell found?
A
In the nucleoid.
13
Q
What is the average cell size of a prokaryotic cell?
A
1um to 0.001mm
14
Q
What are the three components of the cell theory?
A
All cells arise by division of pre-existing cells.
Cells are the basic unit of life.
All living organisms are composed of cells.
15
Q
What is protein primary structure?
A
The specific sequence of amino acids.
16
Q
What is protein secondary structure?
A
The regular coiling or folding which is produced by by hydrogen bonds between NH and CO groups of the polypeptide backbone.
17
Q
What is protein tertiary structure?
A
The irregular folding pattern which is produced by weak interactions between R groups of the polypeptide.
18
Q
What is protein quaternary structure?
A
The overall structure of an oligomeric protein.
19
Q
What is the fluid mosaic model?
A
The fluid mosaic model proposes that proteins are embedded in the phospholipid bilayer in a mosaic or discontinuous fashion.
20
Q
What are the roles of the endomembrane system?
A
Sorting and directing proteins, metabolic functions and carrying out different chemical reactions.
21
Q
What is the cell size range for a eukaryotic cell?
A
10-100 um
22
Q
What is the endosymbiont theory?
A
The theory states that an early ancestor of eukaryotic cells engulfed an oxygen-using non-photosynthetic prokaryotic cell. Eventually the engulfed cell formed a relationship with the host cell and over the course of evolution it evolved into a single cell.
23
Q
What is the cytoskeleton?
A
A network of fibres extending throughout the cytoplasm.
24
Q
What is the role of microtubules?
A
Maintenance of cell shape, cell motility, chromosome movement and organelle movement.
25
What is the role of microfilaments?
Contribute to cell shape.
26
What is the role of intermediate filaments?
Contribute to overall cell shape and also are the major component of nuclear lamina.
27
What is step one of cell signalling?
The signal must be detected by binding to a protein receptor.
28
What is step two of cell signalling?
Signal transduction from an activated receptor to another molecule within the cell.
29
What is the third step of cell signalling?
The response itself. Could be converting a specific enzyme from an inactive form to an active form or vice versa.
30
What enzymes catalyse DNA synthesis?
DNA polymerases.
31
What direction of synthesis does it always go?
5' to 3'
32
What does DNA helicase do during DNA replication?
Separates strands by breaking hydrogen bonds.
33
What does DNA gyrose do during DNA replication?
Removes strains in the DNA molecule by underwinding.
34
What does DNA primase do during DNA replication?
Synthesis short lengths of RNA attached to base pairing to provide an attachment point for DNA polymerase.
35
What does DNA polymerase do during DNA replication>
Removes RNA primer and replaces it with DNA.
36
What are Okazaki fragments?
Short lengths of DNA formed between RNA primers.
37
What does DNA ligase do during DNA replication?
Sets up gaps between fragments.
38
What are the challenges in replication of DNA?
Unwinding the DNA strands, the fact that DNA synthesis needs to be very accurate and the antiparallel nature of DNA strands poses a problem in replication.
39
What is interphase?
Interphase is when the cell is produced, where DNA replication occurs.
40
What happens during G2?
The chromosomes are still uncondensed and cannot be distinguished individually.
41
What is G1?
The first period before DNA replication.
42
What is the order of the lytic cycle of a bacteriophage?
The viral DNA enters the cell, it is then transcribed into mRNA, then translated into protein. When 100 progeny viruses have been assembled, a virus encoded enzyme punctures the cell membrane, ruptures the cell and releases progeny viruses.
43
How do viruses rapidly evolve?
The way viruses reproduce within their host cells makes them particularly susceptible to genetic changes which subsequently drives their rapid evolution.
44
What is a germline mutation?
A germline mutation is a mutation which occurs in gametic cells and can be passed onto offspring.
45
What is a somatic mutation?
A mutation that occurs within a single body cell and cannot be inherited.
46
What best describes the logic of scientific theory?
If my hypothesis is well formulated, I can make predictions which can be tested.
47
If DTTP is added to a culture of rapidly growing bacterial cells, where in the cell would you expect to find the greatest concentration of radioactivity?
The nucleoid.
48
What is the difference between DNA and RNA?
RNA has a hydroxyl group on the 2' carbon of the ribose and DNA does not.
49
When biological membranes are frozen and then fractured they tend to break along the middle of the bilayer. Why>
The hydrophobic interactions that hold the membrane together are weakest at this point.
50
At which level of protein structure are interactions between the side chains most important?
Tertiary.
51
What is a function of a signal peptide?
To direct polypeptides into the ER lumen.
52
What is the arrangement of an Okazaki fragment?
5' RNA nucleotides, DNA nucleotides 3'
53
Where does transcription start?
At a promoter.
54
What is a description of chromosomes, genes and DNA.
A chromosome consists of one double-stranded DNA molecule, which contains discrete units of hereditary information called genes.
55
After the first meiotic division...
Each chromosome is still in the two-chromatid state.
56
What are the three primary mechanisms that contribute to horizontal gene transfer in bacteria are?
Transformation, transduction and conjugation.
57
Why do RNA viruses have a higher rate of mutation?
Because RNA polymerase introduces more errors than DNA polymerase.
58
Bacteria containing recombinant plasmids are often identified by which process?
Exposing the bacteria to an antibiotic that kills cells lacking the resistant plasmid.
59
What is the key enzyme used in PCR?
DNA polymerase,
60
What kind of sequence occurs in front of a gene and initiates gene transcription?
Promoter.
61
What is a silent mutation?
A mutation which does not affect the amino acid specified.
62
What is a missense mutation?
A mutation that causes an amino acid substitution.
63
What is a nonsense mutation?
A mutation that specifies an animo acid into a stop codon.
64
What is an insertion/deletion mutation?
A mutation which involves the gain or loss of one or several base-pairs.
65
What is a frameshift mutation?
A mutation which causes the reading frame of the mRNA codons to be altered. This occurs if the number of bases is deleted or added is not three or a multiple of three.
66
What is a spontaneous mutation?
A mutation that occurs randomly during DNA replication, repair or recombination.
67
What is an induced mutation?
A mutation that has been caused by a mutagen such as radiation or chemicals.
68
What is translation?
Translation is the synthesis of a polypeptide using the information in the mRNA. The cell must translate the nucleotide sequence of an mRNA molecule into the amino acid sequence of a polypeptide.
69
What is the site of translation?
Ribosomes.
70
What is transduction?
Transduction is the process of gene transfer between bacteria that is mediated by the action of bacterial viruses.
71
What is polymer synthesis?
Polymer synthesis in the cell is a set of dehydration reactions which removes water and creates a longer polymer.
72
What is polymer hydrolysis?
Polymer hydrolysis in the cell is a set of hydrolysis reactions which adds water and breaks the polymer down into monomers.
73
How are the chromosomes when the cell is in the interphase stage?
The chromosomes are quite uncondensed and the genes are accessible for the processes of gene expression and the interphase cell is active in protein synthesis, respiration etc.
74
What are the stages of mitosis?
Prophase, prometaphase, metaphase, anaphase and telophase then cytokinesis.
75
What is prophase?
A preparatory stage when the chromosomes uncondense so they can be moved without becoming tangled.
76
What is prometaphase?
Prometaphase is the stage when the nuclear envelope breaks down.
77
What is metaphase?
Metaphase is where the microtubules have moved the chromosomes so that they are aligned at the midpoint of the spindle apparatus.
78
What is anaphase?
Anaphase is where the sister chromatids are pulled apart.
79
What is telophase?
Telophase is where the preparatory events of prophase are undone.
80
What is cytokinesis?
Cytokinesis is the process by which the cell divides to place the separated sets of chromosomes into two individual daughter cells.
81
What happens in prophase 1 (meiotic division)?
During Prophase 1 crossing over or recombination of non-sister chromatids occur.
82
What happens in metaphase 1 (meiotic division)?
Homologous pairs of chromosomes line up.
83
What happens in anaphase 1 (meiotic division)?
The two members of the pairs of homologous chromosomes are separated, this is called segregation.
84
And the end of meiotic division what are the two cells called?
Haploid.
85
What are the details about the second meiotic division?
There is no DNA replication between the two divisions.
The second meiotic division is similar to mitotic division.
During Anaphase 2 the sister chromatids are separated from each other.
86
What is the final outcome of meiosis?
Four, haploid nuclei.
87
How does meiosis produce genetic variation?
Meiosis creates genetic variability by producing new combinations of alleles in gametes. This occurs through independent assortment and recombination. Random fertilisation provides a third mechanism.
88
What are the female chromosomes?
XX.
89
What are the male chromosomes?
XY.
90
How would you tell if a cell was eukaryotic or prokaryotic?
Whether or not the cell was partitioned by internal cell membranes.
91
Why is the electron microscope useful in studying bacteria?
Because bacteria are so small.
92
Why do biological macromolecules have specific conformations?
Because weak interactions bring different parts of the molecule together.
93
Why can humans digest starch but not digest cellulose?
Because humans have enzymes that can hydrolyse the alpha glucoside linkages of starch but not the beta glycoside linkages of cellulose.
94
What observations give support to the endosymbiont theory?
The similarity in size between the cytosolic ribosomes of prokaryotes and the ribosomes within mitochondria and chloroplasts.
95
What organelles are in abundance in the liver to detoxify poisons and drugs?
Smooth ER.
96
The nucleus of a human somatic body cell contains..
Four copies of every gene.
97
What best describes the genetic code?
The set of rules defining how nucleotide triples specify amino acids.
98
What are the three stages of PCR?
Denaturation
Extension
Annealing
99
What does a frequency of recombination of 50% indicate?
That two genes are likely to be located on different chromosomes.
100
Two ways that eukaryotic cells can regulate transcription are?
DNA methylation and histone acetylation.
101
The ability of genes from one species to be expressed in a different species is possible because of which property of the genetic code?
The near universality.
102
Most of the human genome is made up of?
Repetitive DNA
103
Three differences between RNA and DNA
DNA is double stranded, RNA is single stranded.
RNA has a ribose sugar, DNA has a deoxyribose.
RNA has uracil and DNA has thymine.
104
What are the three major steps in processing eukaryotic m-RNA transcripts?
5’ capping
Polyadenylation
Splicing
105
Why are lipids not polymers
Because the monomers are not covalently bonded
106
What is an example of beneficial bacteria and pathogenic bacteria?
E.Coli adds digestion.
| Salmonella causes food borne illness.
