Human Biology Flashcards
(117 cards)
1
Q
What is differentiation?
A
Differentiation is when unspecialised cells such as stem cells have genes switched on so they can perform a specific function or role within the body.
2
Q
Give an example of a differentiated cell type.
A
Nerve cells, red blood cells, cardiac muscle cells
3
Q
What method do somatic cells use to divide?
A
Somatic cells divide by mitosis
4
Q
What method do germline cells use to divide?
A
Meiosis
5
Q
How would we describe the chromosome compliment of somatic cells after cell division?
A
Somatic cells would be described as diploid after cell division
6
Q
How would we describe the chromosome compliment of germline cells after cell division?
A
Germline cells would be described as haploid after cell division
7
Q
If a mutation occurs in a somatic cell line what impact would it have?
A
A mutation in the somatic cell line would directly affect the individual.
8
Q
If a mutation occurs in the germline cell line what impact would it have?
A
A mutation in the germline cell line would have an impact on the offspring
9
Q
What is a benign tumour?
A
A benign tumour is a uncontrolled growth of cells that remains in one place
10
Q
What is a malignant tumour?
A
A malignant tumour is an uncontrolled growth of cells, eg cancer that breaks through the cell membrane and detach, spreading through the body.
11
Q
Identify the base pairing in DNA
A
In DNA, adenine pairs with thymine, and cytosine pairs with guanine
12
Q
What are the differences in bases between DNA and RNA?
A
In RNA thymine is replaced with uracil
13
Q
What type of bonding holds the complimentary base pairs together?
A
Hydrogen bonding holds the complimentary base pairs together, it is a weak bond and once it breaks it allows DNA to unzip
14
Q
What type of bonding holds the phosphate and sugar together in a DNA strand?
A
A phosphodiester bond holds the sugar and phosphate together. This is a strong bond and helps support and maintain the backbone of the structure.
15
Q
What type of sugar is present in DNA molecules?
A
Deoxyribose sugar is present in DNA molecules.
16
Q
What type of sugar is present in RNA molecules?
A
Ribose sugar is present in RNA molecules
17
Q
DNA is described as antiparallel, what does this mean?
A
One strand of DNA runs in the 5’ to 3’ direction, and the other strand runs in the 3’ to 5’ direction
18
Q
How are fragments made in the lagging strand of DNA?
A
Fragments are made at the lagging strand of DNA due to primers only being able to anneal (join) at the replication fork. More primers are added as the DNA strand continues to unzip.
19
Q
Where does transcription take place?
A
Transcription takes place in the nucleus of the cell.
20
Q
What is the starting molecule of transcription?
A
The starting molecule of transcription is DNA.
21
Q
What is the product of transcription?
A
A strand of mRNA is the product of transcription?
22
Q
What are the building blocks of mRNA
A
The building blocks of mRNA are ribonucleotides.
23
Q
Where does translation occur?
A
Translation occurs at the ribosomes
24
Q
What is the starting molecule of translation?
A
The starting molecule of translation is mRNA
25
What is the product of translation?
The product of translation is a polypeptide chain.
26
What are the building blocks of translation?
The building blocks of translation are amino acids.
27
What type of bonds hold the building blocks of translation together?
Peptide bonds hold the amino acids together to form a polypeptide chain.
28
What molecule is responsible for transferring amino acids?
tRNA is responsible for transferring the amino acids to the ribosome in the cell.
29
What is difference between primary mRNA and mature mRNA?
Primary mRNA is made up of both introns and exons.
The introns are removed via splicing, leaving only exons in the mature strand
30
What type of mutation causes a missense mutation?
A missense mutation is caused by a substitution mutation.
31
What impact might the above mutation have?
This may result in the wrong amino acid being incorporated into the polypeptide chain. This could result in a non functional protein, or a protein that serves a different function than originally intended.
32
What is a frameshift mutation?
A frameshift mutation results in the codon sequence being altered. This impacts every subsequent codon as the base in question has either been deleted or inserted.
33
What type of bonding helps give a protein it’s final shape?
Hydrogen bonding helps give a protein it’s final shape.
34
What role does PCR serve?
PCR allows for the amplification of target DNA, making many copies of the original strand.
35
What are the three stages of PCR?
The stages of PCR are denaturation, annealing and extending.
36
In PCR what is the factor that changes between each of the three stages?
Temperature is the variable between the three stages of PCR, allowing the process to be regulated.
37
What enzyme drives the formation of new strands of DNA in PCR?
Taq polymerase drives the formation of new strands of DNA in PCR.
38
Identify two applications of genomic DNA analysis
Genomic DNA analysis can be used for forensic analysis or paternity testing.
39
In DNA probing, how are we able to identify if a gene has been expressed?
A fluorescent dye is used that is bound to the nucleotides. This can be visualised under UV light.
40
Describe the lock and key theory.
In the lock and key theory the enzymes active site is exactly shaped to the substrate. If the substrate does not have the exact shape then a reaction does not occur meaning no product is made.
41
Describe the induced fit model
In the induced fit model the active site is similarly shaped to the substrate. The active site can be changed to accommodate the shape of the substrate to allow a reaction to take place and an end product to be made.
42
What is an anabolic reaction?
An anabolic reaction is the biosynthesis of new molecules from more simple molecules.
43
What is a catabolic reaction?
A catabolic reaction is the degradation of molecules into more simple molecules.
44
What is a competitive inhibitor?
A competitive inhibitor competes with the substrate to join to the enzymes active site. As the active site is occupied by the inhibitor then the substrate can not interact with the enzyme. This means no end product will be made. In order to overcome the effects of a competitive inhibitor we can increase the concentration of the substrate. The effects of a competitive inhibitor are reversable.
45
What is a non competitive inhibitor?
A non competitive inhibitor binds to a site other than the active site. This results in a conformational change to the shape of the protein and in turn the active site. As the active site has changed shape the substrate no longer fits and a reaction can no longer take place. This means no end product will be made. This is an irreversible reaction .
46
What are the three stages of respiration?
The three stages of respiration are glycolysis, the TCA cycle and the electron transport chain.
47
Where does glycolysis take place?
Glycolysis takes place in the cytoplasm
48
Where does the TCA cycle take place?
In the matrix of the mitochondria.
49
Where does the electron transport chain take place?
In the cristae of the mitochondria
50
What are the three potential energy sources that can be used in respiration?
Carbohydrates, fats and proteins
51
How much ATP is produced in anaerobic respiration?
2 ATP
52
Where does anaerobic respiration take place?
Cytoplasm
53
What happened to the pryuvate at the end of glycolysis in anaerobic respiration?
The pryuvate is converted to lactic acid. This is a reversible process and the lactate can be converted back to pryuvate after the oxygen debt is repaid.
54
What happens to hydrogen released during respiration?
Hydrogen binds to the hydrogen acceptors NAD and FAD. They transport the hydrogen the electron transport chain where they are passed through a series of proteins to generate ATP. Oxygen acts as the final hydrogen acceptor, combining to form water.
55
How many ATP are made in aerobic respiration
38 ATP
56
Where does aerobic respiration take place?
Cytoplasm and mitochondria
57
What happens to the pryuvate at the end of glycolysis in aerobic respiration
The pryuvate is converted to Acetyl CoA and transferred to the TCA cycle.
58
What role does creating phosphate play?
Creating phosphate acts as an extra source of energy for muscles when initial ATP stores are depleted.
59
When would slow twitching muscle fibres be useful?
Slow twitching muscles fibres are able to maintain contractions over a long period of time. They are effective in sports such as long distance running, skiing or cycling.
60
When would fast twitch muscle fibres be useful?
Fast twitching muscle fibres are useful in activities that require short bursts of energy like sprinting or weight lifting.
61
What name is given to a nucleotide mutation that causes a protein to be cut short and be non functional?
Nonsense mutation
62
How do splice site mutations affect the production of proteins?
Non encoding introns are included in the mature mRNA transcript or coding exons are excluded from the mRNA transcript
63
In Tay-Sach’s disease, the mutation that causes the disease is a frameshift mutation. What does this mean?
This means that all of the codons after the mutation are altered and will drastically affect the protein produced.
64
Why are chromosomal mutations much more likely to be lethal compared to nucleotide mutations?
There are more substantial, larger pieces of DNA involved in the mutations and hence more likely to include a lethal outcome .
65
What causes haemophilia A?
An inversion of part of the gene that codes for the clotting factor, factor VIII.
66
What was the human genome project
It was the process of identifying and mapping all genes in the human genome.
67
A lot of information regarding genetics can be studied using a variety of computer software. What name is given to this practice?
Bioinformatics
68
Polymerase chain reaction (PCR) is used in order to amplify DNA molecules. Why would you want to do this?
To increase the quantity of DNA molecules to be able to study them more effectively e.g. through visualisation in gel electrophoresis.
69
How many primers are used in PCR and what do they specifically anneal to?
Two, one forward and one reverse, which bind to their complementary base pairs on each of the two template DNA strands.
70
Outline the three stages of the PCR cycle, including the temperatures that each stage is carried out at.
92-98 degrees to melt the DNA by breaking the hydrogen bonds between strands.
50-65 degrees to allow the primers to anneal (bind) to their complimentary regions on the two DNA strands
70-80 degrees to allow the taq polymerase to work on building the new strand
71
If you took a sample of DNA from a crime scene, and found that it only contained 3 DNA molecules, how many molecules of DNA would you have after carrying out 20 rounds of PCR
3 x 2^20 = 3,145,728 copies
72
Give an application of using gel electrophoresis to analyse DNA
Placing a suspect at a crime scene, paternity testing, disease detection, IDing remains that cannot be identified visually,
73
Give an advantage and a disadvantage of personalised medicine.
Advantages - risk prediction for disease, medication response prediction
Disadvantage- DNA profile may be used discriminatory by health providers, employers, insurance companies
74
How would pharmacogenetics end the one size fits all approach to medicine prescription?
It would study the effects of medicine on a genetically diverse group in order to determine which genetic makeup responds best to which medicine
75
What term is used to describe the process whereby cells in the body have had selected genes activated to carry out their specific function?
Cell differentiation
76
Why would a pregnant woman be more worried about a germline mutation found in a lab test than a somatic mutation?
Because germline mutations are heritable, so they can be passed on to the child. Whereas somatic mutations only affect the individual.
77
The test comes back as a benign tumour – what is meant by this, and what term is used to describe a more aggressive tumour?
A benign tumour is non-cancerous and does not spread to other tissue. A more aggressive tumour is termed malignant meaning it’s cancerous and can invade surrounding tissue.
78
During DNA replication, why are the two strands described a leading and lagging strands?
Because DNA polymerase can only add nucleotides in the 3’ - 5’ direction, so one strand is synthesised continuously (leading) and the other in fragments (lagging).
79
What is the name of the enzyme which carries out the replication process?
DNA polymerase
80
Describe the difference between the bond holding paired nucleotides together, and the bonds forming the backbone of the strand
Base pairs are held by hydrogen bonds. The backbone is held together by phosphodiester bonds
81
What is the name of the bond holding amino acids together
Peptide bond
82
What is meant by the term splicing?
Removal of introns from pre-MRNA and joining of exons to form mature MRNA.
83
When forming a 3-D structure, what bonds between different parts of the strand help to give a protein its unique shape?
Hydrogen bonds, ionic bonds, disulfide bridges
84
On what parameter are proteins separated during a gel electrophoresis?
Size/molecular weight
85
A fishmonger has a box of unlabelled fish fillets in his store, and he doesn’t know what species they are. Explain why gel electrophoresis could be a useful technique when trying to figure out what type of fish it is.
Different species have unique protein/DNA banding patterns which can be compared to known references to identify the fish.
86
PCR is made from 3 stages. What variable is changed with each stage to keep the process moving on?
Temperature
87
PCR doubles your DNA count with every cycle. How many cycles does it take to get over 1000 strands of DNA when starting with a single strand?
10 cycles
88
Give an example of an applied use of genomic DNA analysis
Forensic analysis, paternity testing, diagnosing genetic disorders
89
During the DNA probe technique, what is added to the nucleotides to indicate that a gene is being expressed?
A fluorescent or radioactive label
90
What term describes a cell that has become specialised by expressing only certain genes?
Cell differentiation
91
Why are stem cells described as “unspecialised”
They have not yet expressed specific genes to become a particular cell type.
92
What is a therapeutic use of stem cells, and what is one ethical issue related to their use?
Therapeutic use: treatment of leukaemia or Parkinson’s; Ethical issue: destruction of embryos.
93
Why is DNA replication considered 'semi-conservative'?
Because each new DNA molecule contains one original strand and one newly synthesised strand.
94
Name two enzymes involved in DNA replication and briefly state their role
DNA helicase – unzips the DNA; DNA polymerase – adds complementary nucleotides.
95
What type of bonds form between complementary bases, and what type of bond forms the sugar-phosphate backbone?
Hydrogen bonds between bases; strong covalent bonds in the sugar-phosphate backbone.**
96
Where does transcription occur?
Nucleus
97
Where does translation occur?
Ribosome (cytoplasm)
98
What is the final product of transcription?
MRNA
99
What is the final product of translation?
Polypeptide chain/protein
100
What name is given to the type of RNA that carries the genetic code to the ribosome?
MRNA
101
What is meant by the term 'alternative RNA splicing'?
Different combinations of exons are joined together to produce different proteins.
102
What bonds help a protein fold into its final 3D structure?
*Hydrogen bonds, disulfide bridges, ionic bonds.
103
What factor determines the speed at which a protein moves through a gel in gel electrophoresis?
Size/molecular weight of the protein
104
Why might a forensic scientist use gel electrophoresis at a crime scene?
*To compare DNA from suspects with DNA found at the scene.*
105
Below is a section of a chromosome with a deleted base. What type of mutation is this?
Deletion mutation
106
PCR involves changes in which variable during its cycle stages? *
Temperature
107
If PCR doubles DNA every cycle, how many strands will result after 7 cycles starting from 2 strands? *
256 strands
108
Name one medical use of DNA profiling
Identifying genetic disorders or matching organ donors.
109
In a microarray or DNA probe technique, what is used to show where hybridisation has occurred?
A fluorescent or radioactive label
110
Describe how an enzyme-substrate complex forms during an anabolic reaction. Use the lock and key analogy. *
The substrate fits the enzyme’s active site like a key in a lock, allowing a reaction to build up a larger molecule.**
111
What is the name of the site where the substrate binds on an enzyme?
Active site
112
Contrast the effects of competitive and non-competitive inhibitors on enzyme activity.
**Competitive inhibitors bind to the active site and can be overcome by more substrate. Non-competitive inhibitors bind elsewhere and reduce maximum rate.
113
A graph shows a plateau in enzyme activity despite increasing substrate concentration. Explain this shape.
All active sites are saturated; the reaction is at maximum rate.*
114
End product of aerobic respiration?
Carbon dioxide and water
115
End product of anaerobic respiration?
Lactate (in animals)
116
What role does ATP synthase play in respiration?
It produces ATP by adding phosphate to ADP using energy from H+ ions.
117
What molecule allows muscle contraction to continue briefly after ATP runs out?
Creatine phosphate
