Unit 1 Flashcards
1
Q
What is the difference between a somatic cell and a germline cell?
A
A somatic cell is any cell in the body other than cells involved in reproduction, whereas germline cells are gametes (sperm and ova) and the stem cells that divide to form gametes.
2
Q
By what process do somatic stem cells divide?
A
Mitosis.
3
Q
What two types of cell division do germline stem cells undergo?
A
Mitosis and meiosis.
4
Q
What is the purpose of mitosis in germline stem cells?
A
To produce more germline stem cells.
5
Q
How many chromosomes are present in a diploid cell?
A
23 pairs of homologous chromosomes (46 in total).
6
Q
What is the result of meiosis in germline stem cells?
A
Haploid gametes.
7
Q
Describe the two divisions that occur during meiosis.
A
First, homologous chromosomes are separated; second, chromatids are separated.
8
Q
How many chromosomes do haploid gametes contain?
A
23 single chromosomes.
9
Q
What happens to homologous chromosomes and chromatids during meiosis?
A
Homologous chromosomes are separated in the first division, and chromatids are separated in the second division.
10
Q
What is cellular differentiation?
A
It is the process by which a cell expresses certain genes to produce proteins characteristic for that type of cell.
11
Q
How does gene expression relate to cell specialization?
A
By expressing certain genes, a cell produces specific proteins, allowing it to carry out specialized functions.
12
Q
What is the difference between pluripotent and multipotent stem cells?
A
Pluripotent cells can differentiate into all cell types in the body, while multipotent cells can only differentiate into all the types of cells within a particular tissue type.
13
Q
Why are embryonic stem cells considered pluripotent?
A
Because all the genes in embryonic stem cells can be switched on, allowing them to differentiate into any type of cell.
14
Q
Give an example of a type of cell that tissue stem cells can differentiate into.
A
Red blood cells, platelets, phagocytes, or lymphocytes.
15
Q
Where are blood stem cells located?
A
In bone marrow.
16
Q
What types of blood cells can multipotent stem cells in bone marrow produce?
A
Red blood cells, platelets, phagocytes, and lymphocytes.
17
Q
What is the difference between therapeutic and research uses of stem cells?
A
Therapeutic uses involve the repair of damaged or diseased organs or tissues, while research uses involve studying disease development and drug testing.
18
Q
Give two examples of therapeutic uses of stem cells.
A
Corneal repair and regeneration of damaged skin.
19
Q
How can stem cells be used to study disease development?
A
They can be used as model cells to study how diseases develop.
20
Q
What is meant by “model cells” in stem cell research?
A
Cells that are used to study biological processes and disease development.
21
Q
Why are embryonic stem cells valuable for laboratory research?
A
Because they can self-renew under the right conditions.
22
Q
What are some of the key processes that stem cell research helps scientists understand?
A
Cell growth, differentiation, and gene regulation.
23
Q
What is the main ethical concern surrounding the use of embryonic stem cells?
A
Their use involves the destruction of embryos.
24
Q
What is one argument in favor of using embryonic stem cells?
A
They offer effective treatments for disease and injury.
24
Why do cancer cells divide excessively?
Because they do not respond to regulatory signals.
25
What is a tumour?
A mass of abnormal cells resulting from uncontrolled cell division.
26
What can happen when cells in a tumour fail to attach to each other?
They can spread through the body.
27
What is a secondary tumour and how does it form?
It forms when cancer cells spread and establish new tumours in different parts of the body
28
What are the three components of a
DNA nucleotide?
Deoxyribose sugar, phosphate, and a base.
29
What forms the sugar-phosphate backbone of DNA?
The deoxyribose sugar and phosphate.
30
Which bases pair together in DNA?
Adenine pairs with thymine, and guanine pairs with cytosine.
31
What type of bond holds the bases together in a DNA strand?
Hydrogen bonds.
32
What is meant by DNA being "double stranded" and "antiparallel"?
DNA is composed of two strands running in opposite directions, each with a 3' end and a 5' end.
33
At which ends of the DNA strand are the deoxyribose sugar and phosphate located?
The deoxyribose is at the 3' end, and the phosphate is at the 5' end of each strand.
34
What is the overall shape formed by the DNA molecule?
A double helix.
35
What does the base sequence of DNA determine?
The genetic code.
36
When does DNA replication occur?
Prior to cell division.
37
What enzyme is responsible for adding DNA nucleotides during replication?
DNA polymerase.
38
What is a primer, and what role does it play in DNA replication?
A primer is a short strand of nucleotides that binds to the 3' end of the template strand to allow DNA polymerase to start adding nucleotides.
39
To which end of the new strand does DNA polymerase add nucleotides?
The 3' end.
The 3' end.
40
What must happen to the DNA molecule before replication begins?
The DNA is unwound and the hydrogen bonds between bases are broken to form two template strands.
41
Why is the leading strand replicated continuously?
Because DNA polymerase can add nucleotides in one direction only.
42
Why is the lagging strand replicated in fragments?
Because DNA polymerase can only add nucleotides in one direction, requiring multiple starting points on the lagging strand.
43
What enzyme joins the fragments on the lagging strand?
Ligase.
44
What is the purpose of PCR?
To amplify DNA using complementary primers for specific target sequences.
45
What are primers in PCR, and what are they complementary to?
Primers are short strands of nucleotides that are complementary to specific target sequences at the ends of the DNA region to be amplified.
46
What happens to DNA during the heating stage of PCR (92-98°C)?
The DNA strands separate.
47
What is the purpose of cooling the
DNA to 50-65°C during PCR?
To allow primers to bind to target sequences.
48
What happens at 70-80°C during
PCR?
Heat-tolerant DNA polymerase replicates the region of DNA.
49
Why is a heat-tolerant DNA polymerase used in PCR?
Because it can withstand the high temperatures required during the heating stage of PCR.
50
Name three practical uses of PCR.
To help solve crimes, settle paternity suits, and diagnose genetic disorders.
51
What are the two main stages involved in gene expression?
Transcription and translation.
52
Are all the genes in a cell expressed?
No, only a fraction of the genes in a cell are expressed.
53
Name the three types of RNA involved in gene expression.
mRNA (messenger RNA), tRNA (transfer
RNA), and rRNA (ribosomal RNA).
54
Describe the structure of RNA.
RNA is single-stranded and composed of nucleotides containing ribose sugar, phosphate, and one of four bases: cytosine, guanine, adenine, and uracil.
55
Which sugar is found in RNA nucleotides?
Ribose sugar.
56
What base is found in RNA instead of thymine?
Uracil.
57
What is the role of messenger RNA (mRNA)?
It carries a copy of the DNA code from the nucleus to the ribosome.
58
Where is mRNA transcribed and where is it translated?
mRNA is transcribed in the nucleus and translated in the cytoplasm by ribosomes.
59
What is a codon?
A triplet of bases on the mRNA molecule.
60
What does each codon code for?
A specific amino acid.
61
What is the function of transfer RNA (tRNA)?
To carry its specific amino acid to the ribosome.
62
What causes a tRNA molecule to fold?
Complementary base pairing.
63
What are the two key features of a tRNA molecule?
An anticodon (an exposed triplet of bases) and an attachment site for a specific amino acid.
64
What forms the structure of a ribosome?
Ribosomal RNA (rRNA) and proteins.
65
What is the role of RNA polymerase in transcription?
It moves along DNA, unwinds the double helix, breaks hydrogen bonds, and synthesises a primary transcript of mRNA.
66
What happens to the DNA molecule during transcription?
The double helix is unwound and hydrogen bonds between bases are broken.
67
How is the primary mRNA transcript formed?
By complementary base pairing of RNA nucleotides with the DNA template strand.
68
Which RNA base pairs with adenine during transcription?
Uracil.
69
What are introns?
Non-coding regions of the primary transcript.
70
What are exons?
Coding regions of the primary transcript.
71
What happens to introns during
RNA splicing?
They are removed.
72
What happens to exons during RNA splicing?
They are joined together to form the mature transcript.
73
Is the order of exons changed during splicing?
No, the order of exons remains unchanged.
74
Where does translation occur?
At a ribosome in the cytoplasm.
75
What signals the start and end of translation?
A start codon begins translation and a stop codon ends it.
76
How do anticodons on tRNA pair with codons on mRNA?
By complementary base pairing.
77
What is the result of translation?
A sequence of amino acids forming a polypeptide.
78
What type of bond joins amino acids during translation?
Peptide bonds.
79
What happens to each tRNA after it delivers its amino acid?
It leaves the ribosome.
80
How can different proteins be expressed from the same gene?
Through alternative RNA splicing.
81
What determines which mature mRNA transcript is produced?
Which exons are retained during splicing.
81
How are amino acids linked together to form polypeptides?
By peptide bonds.
82
What causes a polypeptide to fold into a three-dimensional shape?
Interactions between individual amino acids.
83
What holds the folded protein structure together?
Hydrogen bonds and other interactions.
84
Why do proteins have different functions?
Because they have a large variety of shapes.
85
What determines an organism's phenotype?
Proteins produced as a result of gene expression.
86
Besides gene expression, what else can influence phenotype?
Environmental factors.
86
What is a mutation?
A mutation is a change in the DNA.
87
What effects can mutations have on proteins?
They can result in no protein or an altered protein being synthesised.
88
What causes a single gene mutation?
An alteration of a DNA nucleotide sequence due to substitution, insertion, or deletion of nucleotides.
89
Name the three types of nucleotide substitution mutations.
Missense, nonsense, and splice-site mutations.
90
What happens during a missense mutation?
One amino acid is changed for another.
91
What possible effects can a missense mutation have on a protein?
It may result in a non-functional protein or have little effect.
92
What is the result of a nonsense mutation?
A premature stop codon is produced, resulting in a shorter protein.
93
What is a splice-site mutation?
A mutation that affects the regions where splicing of mRNA occurs.
94
What can splice-site mutations result in?
Some introns being retained and/or some exons not being included in the mature transcript.
95
What causes a frame-shift mutation?
Insertion or deletion of nucleotides.
96
Why do frame-shift mutations have a major effect on the protein produced?
Because they change all of the codons and amino acids after the mutation.
97
What are the four types of chromosome structure mutations?
Duplication, deletion, inversion, and translocation.
98
What happens in a duplication mutation?
A section of a chromosome is added from its homologous partner.
99
What happens in a deletion mutation?
A section of a chromosome is removed.
100
What happens in an inversion mutation?
A section of a chromosome is reversed.
101
What happens in a translocation mutation?
A section of a chromosome is added to a chromosome that is not its homologous partner.
102
Why are chromosome structure mutations often lethal?
Because they involve substantial changes in the chromosome.
103
What is the genome of an organism?
The genome is the organism's entire hereditary information encoded in DNA.
104
What does a genome consist of besides genes?
Other DNA sequences that do not code for proteins.
105
What is genomic sequencing?
The process of determining the sequence of nucleotide bases in individual genes and entire genomes.
106
What can genomic sequencing determine?
The sequence of nucleotide bases.
107
What role do computer programs play in genomic sequencing?
They are used to identify base sequences by looking for sequences similar to known genes.
108
How can computer programs identify base sequences?
By comparing them to sequences of known genes.
109
What tools are required to compare sequence data?
Computer and statistical analyses, also known as bioinformatics.
110
Why might an individual's genome be analysed?
To predict the likelihood of developing certain diseases.
111
What is pharmacogenetics?
The use of genome information in the choice of drugs.
112
How is pharmacogenetics used in medicine?
It helps determine the most effective drug and dosage for treating a person's disease.
113
What is personalised medicine?
The use of an individual's personal genome sequence to tailor medical treatment.
114
How can an individual's genome influence drug choice and dosage?
By identifying which drugs will be most effective and what dosage is most appropriate for that individual.
115
What are metabolic pathways?
Integrated and controlled pathways of enzyme-catalysed reactions within a cell.
116
What types of steps can metabolic pathways include?
Reversible steps, irreversible steps, and alternative routes.
117
What are anabolic reactions, and what do they require?
Anabolic reactions build up large molecules from small molecules and require energy.
118
What are catabolic reactions, and what do they release?
Catabolic reactions break down large molecules into smaller molecules and release energy.
119
What controls metabolic pathways?
The presence or absence of particular enzymes and the regulation of the rate of reaction of key enzymes.
120
What is the induced fit model of enzyme action?
It occurs when the enzyme's active site changes shape to better fit the substrate after the substrate binds.
120
What happens to the enzyme's active site during induced fit?
It changes shape to more closely match the substrate.
121
What is the affinity of substrate molecules for the active site?
Substrate molecules have a high affinity for the active site.
122
Why do products leave the active site after a reaction?
Because they have a low affinity for the active site.
123
How does the presence of substrate or removal of product affect reversible reactions?
It drives the sequence of reactions in a particular direction.
123
What is competitive inhibition?
When inhibitors bind at the active site, preventing the substrate from binding.
124
How can competitive inhibition be reversed?
By increasing the substrate concentration.
125
Where do non-competitive inhibitors bind?
Away from the active site.
126
How do non-competitive inhibitors prevent the substrate from binding?
They change the shape of the active site.
127
Can non-competitive inhibition be reversed by increasing substrate concentration?
No, it cannot be reversed by increasing substrate concentration.
128
What is feedback inhibition?
When the end-product of a pathway inhibits an earlier enzyme in the same pathway.
129
When does feedback inhibition occur, and what does it do?
It occurs when the end-product reaches a critical concentration, blocking the pathway to prevent further synthesis of the end-product.
130
What is glycolysis and where does it occur?
Glycolysis is the breakdown of glucose to pyruvate, and it occurs in the cytoplasm.
131
What is required during the energy investment phase of glycolysis?
ATP is required for the phosphorylation of glucose and intermediates.
132
What happens during the energy pay-off phase of glycolysis?
More ATP is generated, resulting in a net gain of ATP.
133
What is the net result of glycolysis in terms of ATP?
A net gain of ATP.
134
What happens to pyruvate in aerobic conditions?
It is broken down to an acetyl group.
135
What does the acetyl group combine with to form acetyl coenzyme A?
It combines with coenzyme A.
136
In the citric acid cycle, what does the acetyl group combine with to form citrate?
It combines with oxaloacetate.
137
What happens to citrate during the citric acid cycle?
It is gradually converted back into oxaloacetate through a series of enzyme-controlled steps.
138
What are the products of the citric acid cycle?
ATP is generated and carbon dioxide is released.
139
Where does the citric acid cycle take place?
In the matrix of the mitochondria.
140
What is the role of dehydrogenase enzymes in glycolysis and the citric acid cycle?
They remove hydrogen ions and electrons and pass them to NAD, forming NADH.
141
What molecule do hydrogen ions and electrons reduce to form
NADH?
The coenzyme NAD.
142
Where is NADH passed after it is formed?
To the electron transport chain on the inner mitochondrial membrane.
To the electron transport chain on the inner mitochondrial membrane.
143
What happens to electrons in the electron transport chain?
They are passed along the chain, releasing energy.
144
Where is the electron transport chain located?
On the inner mitochondrial membrane.
145
What does the energy released by the electron transport chain do?
It allows hydrogen ions to be pumped across the inner mitochondrial membrane.
146
How is ATP produced by ATP synthase?
The flow of hydrogen ions back through ATP synthase results in the production of ATP.
147
What happens to hydrogen ions and electrons at the end of the electron transport chain?
They combine with oxygen to form water.
148
What is the role of ATP in the cell?
ATP is used to transfer energy to cellular processes that require energy.
149
Which cellular processes require
ATP?
Any processes in the cell that require energy
150
What happens in muscle cells during vigorous exercise when oxygen is insufficient?
The muscle cells do not get enough oxygen to support the electron transport chain.
151
What is pyruvate converted into under anaerobic conditions?
Pyruvate is converted into lactate.
152
What is transferred from NADH to pyruvate to form lactate?
Hydrogen ions are transferred from NADH to pyruvate.
153
Why is the regeneration of NAD important during glycolysis?
Regenerating NAD allows glycolysis to continue and maintain ATP production.
154
What builds up in muscles during vigorous exercise, causing fatigue?
Lactate accumulates, causing muscle fatigue.
155
What is meant by "oxygen debt"?
It is the amount of oxygen needed after exercise to restore the body to resting conditions, including converting lactate back to pyruvate and glucose.
156
What happens to lactate in the liver after exercise is complete?
It is converted back into pyruvate and then glucose.
157
What energy source is used to convert lactate back to pyruvate and glucose?
Energy from respiration is used.
158
How do slow-twitch muscle fibres contract compared to fast-twitch fibres?
They contract more slowly but can sustain contractions for longer.
159
What types of activities are slow-twitch fibres suited for?
Endurance activities like long-distance running, cycling, or cross-country skiing.
160
Which type of respiration do slow-twitch fibres rely on for ATP production?
Aerobic respiration.
161
Name three features of slow-twitch muscle fibres that support aerobic respiration.
They have many mitochondria, a large blood supply, and a high concentration of myoglobin.
162
What is the major storage fuel of slow-twitch fibres?
Fats.
163
How do fast-twitch muscle fibres contract?
They contract quickly over short periods.
164
What type of physical activities are fast-twitch fibres suited for?
Activities such as sprinting or weightlifting.
165
How do fast-twitch fibres produce
ATP?
Mainly through glycolysis.
166
How do fast-twitch fibres compare to slow-twitch fibres in terms of mitochondria and blood supply?
They have fewer mitochondria and a lower blood supply.
167
What is the major storage fuel in fast-twitch muscle fibres?
Glycogen.
168
Do most humans have only one type of muscle fibre?
No, most human muscle tissue contains a mixture of both types.
169
How do the muscle fibre patterns of athletes differ?
Athletes show distinct patterns of muscle fibres that reflect the demands of their sporting activities.
