Final Material Flashcards
(235 cards)
1
Q
How many amino acids comprise a protein?
A
20 different amino acids encoded by 20 different letters
2
Q
What are the letters of the 4 different nucleotides that comprise DNA?
A
A (Adenine), G (Guanine), T (Thymine) and C (Cytosine)
3
Q
What are 2 ways amino acids link together to form a type of protein?
A
- alpha-helix
- beta strand (or beta sheet)
4
Q
Nucleotides that come together in pairs which form the DNA double helix structure is called what?
A
A codon
5
Q
What’s the central dogma about the flow of genetic information?
A
DNA -> RNA -> protein
6
Q
What’s the central dogma on what are the 2 steps in which the flow of genetic information occurs?
A
- Transcription (DNA -> RNA)
- Translation (RNA -> Protein)
7
Q
What’s the intermediate molecule between DNA and protein?
A
RNA
8
Q
How can an alphabet of 4 letters give rise to millions of proteins?
A
We need something (RNA) that can transcribe and link the 4 letters of DNA to 20 letters of proteins
9
Q
What’s mRNA?
A
A messenger RNA
10
Q
What’s DNA?
A
A polymer of nucleotides (2 complementary strands)
11
Q
What’s RNA?
A
A polymer of nucleotides (single strand)
12
Q
What’s a protein?
A
Chain or polymer of amino acids
13
Q
What’s the unit of information?
A
The codon
14
Q
The DNA alphabet comprises how many “letters”?
A
4 “letters”
15
Q
The protein alphabet comprises how many “letters”?
A
20 “letters”
16
Q
How many possible amino acids can a singlet DNA code form?
A
4 possible amino acids
17
Q
How many possible amino acids can a doublet DNA code form?
A
16 possible amino acids (4^2 -> 4 to the power of 2)
18
Q
How many possible amino acids can a triplet DNA code form?
A
64 possible amino acids (4^3 -> 4 to the power of 3)
19
Q
What’s the 3 letter mRNA codon table?
A
- A genetic code for protein synthesis
- The codon table links each amino acid (20) to mRNA codons
- There are 16 different blocks, which include 64 codons (some that indicate stop or the start of transcription)
- Each block specifies the 1st and 2nd letter
20
Q
What’s an example of an amino acid that has 6 different codons?
A
Lucine
21
Q
The DNA coding strand is always what direction?
A
Always 5’ to 3’ direction
22
Q
The mRNA sequence is a perfect copy of what sequence?
A
The mRNA sequence is a perfect copy of the DNA sense sequence, except T is subtituted with U (uracil)
23
Q
What will be used to build the mRNA?
A
The anti-sense template
24
Q
Which letter from the DNA sense sequence is replaced by a U in the mRNA sequence?
A
The letter T is substituted with U (uracil)
25
Illustrate the difference between a sense DNA coding strand and an anti-sense DNA template strand
Sense: 5' ATGCATGCG 3'
Anti-sense: 3' TACGTACGC 5'
26
What is translated into a protein sequence?
The mRNA codons
27
What can you predict about a protein with the mRNA codons?
if protein is hydrophilic or hydrophobic
28
Can only one nucleotide triplet encode a specific amino acid?
- No, multiple codons can encode the same amino acids
- Since there are 64 triplet combinations and 20 amino acids
- The genetic code is degenerate
29
How can we conclude that mutations may not change anything about the protein at all?
Because multiple codons can encode the same amino acids
30
What's the difference between determining a protein primary structure from a DNA sequence and determining a DNA sequence from a protein primary structure?
- If you know the DNA sequence, you can accurately determine the protein primary structure
- If you know the protein primary structure you cannot determine the DNA sequence
- Because we are always uncertain about the 3rd base in the codon
31
What will happen if you put a gene into any kind of living organism?
It’ll express that protein (the protein may not function)
32
Why do we say the genetic code is universal?
- Because if you put a gene into any kind of living organism, it’ll express that protein even though the protein may not function
- Ex: if you take the green fluorescent gene from the cells of a jellyfish and implant it in a bacteria, a yeast cell and a mouse, they will all express that green fluorescent protein one way or another
33
What's the structure of a gene?
- All genes have a start codon, a stop codon, a promoter and a terminator
- Start with promoter
- Then the start codon and stop codon (end of the protein sequence but not the end of the mRNA sequence)
- Then the terminator
34
What's the function of the promoter in the gene structure?
Functions as a docking site, a place for the gene to sit down
35
What structures of the gene structure control where RNA polymerase will start transcribing the DNA sequence into an mRNA transcript?
The promoter and start codon
36
What letter sequence box is absolutely conserved in every promoter?
TATAAT box
37
What are the functions of RNA polymerase, the AAAA tail and mRNA in the gene structure?
- RNA polymerase transcribes a AAAA tail that is NOT translated
- The AAAA tail protects the mRNA until it is translated
38
What do promoters bind?
Promoters bind RNA polymerase
39
What does the promoter interact with?
Transcription Factors
40
What are the functions of transcription factors?
- They can influence the transcription start site
- They recruit RNA polymerase
41
What are the functions of the steps involved in how the promoter interacts with transcription factors to make RNA polymerase?
These steps control gene expression and can produce alternative yet functional proteins that are highly specialized for a cell type or stage in development
42
The template strand serves as a template for what?
For building and mRNA
43
How can transcription factors give you mRNA?
With transcription factors binding to the TATAAT box, you will have mRNA
44
What is considered a translation machine?
The ribosome
45
How do the sequences associated with nucleic acids and proteins interact with ribosomes?
They are linked mechanistically through the ribosome
46
Describe the structure of the ribosome
- Structure comprised of large subunit and small subunit
- The 1st binding site is called the A-site (aminoacyl) and is only functional when small and large subunits bind together -> it's what the mRNA codes on
- Another binding site is the E-site (exit) and it will deal with covalent bonds
- The last binding site is the P-Site (peptidyl)
47
What's the function of tRNA?
- Found in a ribosome
- It binds to amino acids
- It transfers amino acids to a mRNA molecule bound to a ribosome
- It's reading mRNA and reading the amino acid
48
What's the function of the ribosome?
- Where mRNA is translated into amino acid sequences
- Where the sequences associated with nucleic acids and proteins are linked mechanistically
49
How can a tRNA be recharged?
By binding to an amino acid
50
Describe the ribosome in action
- mRNA binds to the small subunit and the anticodon of a charged tRNA (+Met) binds the first codon
- The large subunit allows another tRNA+aa to enter
- A peptide bond is formed, the discharged tRNA is released and a new charged tRNA enters
51
When can the large subunit bind to the mRNA, tRNA and small subunit?
When mRNA binds to the small subunit and the anticodon of a charged tRNA (+Met) binds the first codon
52
How can you make a lot of similar proteins, which is essential for when releasing a signal?
Because you can have multiple ribosomes working on the same RNA at the same time
53
What determines where the sequence starts being read out on the mRNA interacting with a ribosome?
The start codon
54
When does the ribosome release the polypeptide?
- Ribosome reaches a stop codon on mRNA which is in line with the release factor
- The release factor in the ribosome promotes hydrolisis of GTP, which creates the energy to release the polypeptide
55
What does the sequence of the gene determine?
The amino acid sequence of the protein and its shape and function
56
Bacteria have ribosomes but they don’t have what?
Endoplasmic riticulum
57
What's a silent mutation in DNA and how does it affect the shape and function of a protein?
- Mutations that occur in the 3rd base of the codon which will be silent
- It has not effect on the protein sequence or function, only on the nucleic acids
- Redundancy among codons
58
What's a missense mutation in DNA and how does it affect the shape and function of a protein?
- Results in an amino acid substitution (change from Pro to Thr)
- Protein function might change
59
What's a nonsense mutation in DNA and how does it affect the shape and function of a protein?
- Substitutes a stop codon for an amino acid
- Protein truncated, loss of function
60
Changes in the chemical nature of what group are very disruptive?
- R-group
61
How is sickle cell anemia disease caused?
- By a single change in one amino acid in a hemoglobin (acidic to non-polar)
- It has devastating effects on the hemoglobin
62
What's a frameshift mutation?
- Mutation that leads to a different protein, or truncated-loss of function or gain of function
- Such mutations are the cause of many diseases
- Ex: AGCGUACCCUAC (Ser-Val-Pro-Tyr) to AGCGCCCUACUU (Ser-Ala-Leu-Leu)
63
What form of frame-shift mutation is particularly disruptive?
Frame-shift mutations that truncate the protein
64
What's gain-of-function?
- A receptor that activates cell division without a signal
- Makes the protein lose the ability to respond to external signals
65
What's required for all life?
Cell division
66
What happens when cell division goes wrong?
Unicellular organisms die and multicellular organisms get diseases
67
The one cell embryo is what kind of cell?
A stem cell
68
What's the name of the cell that's needed to produce any other cell?
Stem cell
69
What's the self-sustaining hierarchical differentiation of cells?
- Stem cells
- Progenitor cells
- Mature cells
70
What do stem cells produce?
- Red and white blood cells
- These cells are also in our skin
71
How many cells does a human have?
10^13 cells
72
What's the number of chromosome replications occurring per generation in humans?
10^16 divisions in the lifetime (10^13 -10^14 cells)
73
"Somatic" cells have what kind of cell division?
Binary tree division
74
"Stem" or "germ" cells have what kind of cell division?
One stem cell divisions
75
True of False: The cell cycle is different for different living cells
- False: The cell cycle is universal across all living cells
- The order never changes, and each step must be completed before the next step starts
76
What happens to cell division as you age?
Errors in cell division increase as you age
77
In what phase of the cell cycle does the cell actually undergo cell division?
During the "M" or mitosis phase
78
What does the cell cycle do?
It describes a series of events that occur during cell division
79
What about the cell cycle varies between organisms?
- The time required to complete each step, and for the entire cycle
- Ex: embryonic division are quite rapid because they lack the g1 & g2 phase since the cells are trying to reduce their size
80
The length of the cell cycle for each cell type is what?
It's stereotyped
81
How long does a human cell take to divide?
24 hours
82
Cell divisions always occur at what angle from the last cell?
90º angle
83
What's controlled for cyclin genes?
- The timing of expression of cyclin genes
- As a result, the concentration of cyclin protein is also controlled
84
What kind of cells have cyclin dependent Kinase?
All eukaryotic cells
85
What's controlling cyclins in the cell cycle?
Transcription factors
86
How do cyclins interact with the cell cycle?
- Cyclin expression cycle
- There's a set of cyclins specific to each phase for the cell cycle
87
What controls transitions in all eukaryotic cells?
Cyclin-dependent kinase (Cdk)
88
What needs to happen for Cdk to be active?
It needs to bind itself to ATP and phosphorylate itself which can only be done when it’s bound to a cyclin (co-enzyme)
89
When's the only time that the kinase is active?
When the cyclin is bound to it
90
Describe the Cdk cycle
1. cyclin binds to Cdk1
2. A phosphate-donating protein (kinase) binds to Cdk
3. Cyclin/Cdk complex is phosphorylated
4. ATP binds to Cdk
6. Cyclin-Cdk is now active
7. The cyclin specifies the targets
8. ATP binds to the target protein
8. Cdk phosphorylates the target and releases it and seperates from cyclin
9. Back to step 1
91
What are the different phases of the cell cycle?
- G1 phase (interphase) -> cell growth
- S phase (interphase) -> DNA synthesis
- G2 phase (interphase) -> cell growth
- Mitosis phase (mitotic phase)
- Cytokinesis phase (mitotic phase)
92
In what phase of the cell cycle do we see the formation of 2 daughter cells?
Mitotic phase
93
What's E2F and what is it needed for?
- Transcription factor
- Needed to express 100s of genes in G1 that are needed for all later phases of the cell cycle
- START of cell cycle
94
Describe the Rb regulation of the cell
- Unphosphorylated Rb binds transcription factor E2F
- E2F can't bind the DNA, and transcription is blocked
- Cell growth then triggers the phosphorylation of Rb
- Phosphorylated Rb releases E2F, which binds the DNA and turns on gene expression, thus advancing the cell cycle
95
When is START detected?
- When Rb/Whi5 disappears
- By inhibiting the inhibitor, you can allow the G1 phase do its work
96
What triggers the end of mitosis?
When Rb/Whi5 re-appears
97
What's the inhibitor of the transcription factor?
Rb
98
In what phase of the cell cycle is DNA replicated?
- S phase
- Also where chromosomes are replicated
99
What kind of chromosomes do eukaryotic cells have?
At least three linear chromosomes
100
What kind of chromosomes do prokaryotic cells have?
A single circular chromosome
101
How many chromosomes do we have?
22
102
What kind of molecule has 2 anti-parallel strands linked by hydrogen bonds?
Each DNA molecule
103
What is necessary to occur in order to replicate the DNA?
Each anti-parallel strand must be copied
104
What needs to have occurred for the cell to commit to enter mitosis?
The DNA has to be replicated
105
What are the different phases of mitosis in eukaryotes?
1. Prophase
2. Prometaphase
3. Metaphase
4. Anaphase
5. Telophase
6. Cytokinesis (result)
106
Describe the prophase of mitosis in eukaryotes
- Chromosomes condense and become visible
- Spindle fibers emerge from the centrosomes
- Nuclear envelope breaks down
- Nucleolus disappears
107
Describe the prometaphase of mitosis in eukaryotes
- Chromosomes continue to condense
- Kinetochores appear at the centrosomes
- Mitotic spindle microtubules attach to kinetochores
- Centrosomes move toward opposite poles
108
Describe the metaphase of mitosis in eukaryotes
- Mitotic spindle is fully developed, centrosomes are at opposite poles of the cell
- Chromosomes are lined up at the metaphase plate
- Each sister chromatid is attached to a spindle fiber originating from opposite poles
109
Describe the anaphase of mitosis in eukaryotes
- Cohesin proteins binding the sister chromatids together break down
- Sister chromatids (now called chromosomes) are pulled toward opposite poles
- Non-kinetochore spindle fibers lengthen, elongating the cell
110
Describe the telophase of mitosis in eukaryotes
- Chromosomes arrive at opposite poles and begin to decondense
- Nuclear envelope material surrounds each set of chromosomes
- The mitotic spindle breaks down
111
Describe cytokinesis
- The end result of all of the different phases of mitosis in eukaryotes
- The separation of daughter cells
- For animal cells: microfilaments form a cleavage furrow that separates the daughter cells where the contractile ring is
- For plant cells: a cell plate separates the daughter cells where the golgi vesicles are
112
What phases of mitosis in eukaryotes are completed in preparation for the metaphase?
- Prophase
- Prometaphase
113
What phases of mitosis in eukaryotes are completed in preparation for cytokinesis?
- Anaphase
- Telophase
114
What's an additional requirement for the cytokinesis of plant cells?
Exocitosis
115
How does division of nuclear material occur in prokaryotes?
- Occurs through binary fission
- As the chromosome is replicated, the 2 copies move to opposite ends of the cell by an unknown mechanism
116
How does separation of the daughter cells occur in prokaryotes?
FtsZ proteins assemble into a ring that pinches the cell in 2
117
How does division of nuclear material occur in animal cells?
- A mitotic spindle forms from the centrosomes
- The nuclear envelope dissolves
- Chromosomes attach to the mitotic spindle, which separates the chromosomes and elongates the cell
118
What happens if an error occurs in cell division?
- Checkpoints in the cell cycle prevent the cell from moving to the next step
- Act as tumour suppressors
- Diseases don't occur due to errors in cell division, but rather from a lack of checkpoints that'll detect these errors
119
Why are the cell cycles very error-prone?
Since they have to adapt to different changes (ex: different environment, changes in temperature)
120
What are errors that could be detected by the checkpoint in the G1 phase of the cell cycle?
- Not enough nutrients
- Cell volume is too small (cell needs to be big enough to succeed)
121
What are errors that could be detected by the checkpoint in the S and G2 phase of the cell cycle?
- DNA replication not complete
- DNA damage
122
What are errors that could be detected by the checkpoint in the M phase of the cell cycle?
- Chromosomes not attached
- Chromosomes have not separated
123
What are the checkpoints in the cell cycle made out of?
Enzymes and other proteins
124
What are the inputs sensed in the G1 phase of the cell cycle?
- Cell volume/size
- Nutrient concentration
125
What's the expression of genes needed to START and finish the cell cycle?
1. G1 CDK (cyclin D)
2. TF inhibitor (Rb)
3. TF (E2F)
4. CDK (cyclin E)
126
What is the S phase of the cell cycle essential for?
- "Proofreading"
- Prevents mutations
- Ex: “Bubble” caused by G - T mismatch cannot form a hydrogen bond -> proofreading “pocket” replaces T with C
127
What is the G1 phase of the cell cycle essential for?
- Where cells commit to entering the cell cycle
- Controlling START
128
What happens when there's a bubble in the DNA polymerase?
A "bubble" forms in the area of mismatch
129
What is the M phase of the cell cycle essential for?
- Chromosome attachment (from metaphase to anaphase) -> there's a specific checkpoint that’ll stop cells from going into anaphase if there is a missing attachment
- Chromosome separation (from anaphase to cytokinesis) -> another checkpoint will prevent Cytokinesis from happening too early
130
Where does cancer originate?
- In the cell cycle
- Happens when things go wrong in the cell cycle
131
A healthy cell has what?
A healthy cell cycle
132
What did Susumu Tonegawa and others do?
They convinced mice that they had been shocked in one place when really they had been shocked somewhere else
133
What's a stimulus and examples of it?
- Any input
- Can be light, sound, touch, taste, gravity, movement, smell
134
How does the brain work (in a very broad and general way)?
- First, it takes in a stimulus
- Then, you have to process that information
- Then, you determine what to do next (behaviour)
135
What's processing in the brain?
- What to do with the information (stimulus)
- Can be simple or complex
136
What's an example of simple processing in the brain?
A reflex when you touch a hot pan or the need to breathe harder when running
137
What's an example of complex processing in the brain?
- Taking an exam or determining when and whether to swing at a baseball pitch
- Doesn't have to be slow
138
What's behaviour?
- Anything you do in response to the stimulus and processing
- Ex: removing your hand from the pan or filling in the circle for answer A
139
What's an action potential?
An electrochemical wave, driven by the movement of ions along their electrical and concentration gradients
140
What are neurons?
Cells in the brain that contain the same complement of organelles, cytoskeleton, DNA, etc., as other cells
141
What are neurons composed of?
- They have cell bodies that contain organelles, cytoskeleton & DNA
- Neurons have mitochondria, a nucleus, golgi apparatus, ribosomes, smooth and rough endoplasmic riticulum
142
What are the few features of a neuron that makes them unique?
- Dendrites
- Axon
- Synapse
143
What are dendrites?
- Processes near the cell body
- They receive input from other neurons
144
What are axons?
- Main conducting unit of the neuron
- Connects one cell body to another cell body
- Conveys information by propagating an electrical signal (action potential)
- Axons can be very long (they can go from spinal cord to the very tip of your finger) & can be very small (connecting 2 cells next to each other in the brain)
145
What's a synapse?
- Chemical connections that occur between the axon of one neuron and the dendrites of another neuron
- Used to communicate signals from one neuron to another
- Where the axon of one cell connects to the dendrites of another cell
146
What are checkpoints in the cell cycle signalling to the cycle to do?
To slow everything down
147
What happens when errors are detected in the cell cycle?
- The checkpoint delays the transition to the next phase
- This delay allows repair systems to respond and fix the error
- The checkpoint is then satisfied and the cell enters the next phase
148
What specifically fixes errors in the cell cycle?
Repair systems
149
Describe the checkpoint in the G1 phase
- Asks is environment favourable?
- If yes, then START transition occurs
- If yes, cell enters cell cycle and proceed to S phase
150
Describe the checkpoint in the S and G2 phase
- Asks is all DNA replicated?
- Asks is environment favourable?
- If yes, G2 to M transition occurs
- If yes, cell enters mitosis
151
Describe the checkpoint in the M phase
- Asks are all chromosomes attached to the spindle?
- If yes, Metaphase to Anaphase transition occurs
- If yes, trigger anaphase and proceed to cytokinesis
152
In each phase of the cell cycle, what do checkpoints do?
Monitor processes and conditions
153
For every type of cell, there is a type of ____?
Cancer
154
What are some characteristics of cancer?
- Abnormal responses to environmental signals (ex: increased proliferation, ability to disperse into “colonies”)
- Abnormal metabolism (ex: the Warburg effect)
- Abnormal proliferation or resistance to environmental or genetic stress
155
What do normal cells with too much damage undergo?
Apoptosis: programmed cell death
156
What can a cancer originate from?
- Losing control of a cellular process
- Losing a checkpoint that monitors a cellular process
- Losing control and a checkpoint (this leads to very serious cancer)
157
Does every cell have an accompanying type of cancer?
Yes, for every type of cell, there is a type of cancer
158
Where do we have epothelia?
On the cells on our skin (dermis)
159
What pumps out anaerobic respiration products?
Cancer cells
160
What causes homeostatis?
Normal cell division and normal apoptosis
161
What are 2 ways cells can cause a tumor?
- Increased cell division and normal apoptosis (issue with signalling)
- Normal cell division and decreased apoptosis
162
What causes apoptosis?
- Programmed cell death occurs when cells have an issue they can’t fix, they eliminate themselves from the population
- Apoptosis is a checkpoint response -> I can’t fix it so let’s get rid of it
- If body doesn’t recognize cell damage, it won’t undergo apoptosis, but if signalling defect, there will be apoptosis
163
Describe the pathway of maintaining control with cell division
A growth factor stimulates the cell to divide
↓
Growth factors bind to receptors on the cell surface
↓
The activated receptor triggers an appropriate response
↓
The response of effectors is controlled
164
Describe the pathway of losing control with cell division
A growth factor stimulates the cell to divide
↓
Growth factors bind to receptors on the cell surface
↓ (Mutation in the receptor)
The activated receptor triggers an inappropriate response
↓ (Mutation in an effector)
The response of effectors is uncontrolled
165
What happens when your cells follow the "losing control" pathway to cell division?
- Your cells start to behave as if you’ve injured yourself but you haven’t
- They think you have because they’re getting signals that say grow grow grow
166
What are the 2 paths to cancer?
- Oncogenes (overactivity mutation - gain of function)
- Tumour suppressors (under activity mutation - loss of function)
167
Describe the oncogene (overactivity mutation - gain of function) path to cancer
- Normal cell
- Single mutation event
- Creates oncogene
- Activating mutation enables oncogene to promote cell transformation
- Cells en route to cancer
168
What's an oncogene?
Thing in the receptor or downstream the receptor that signals for cells to proliferate (divide) without there being a reason to proliferate
169
Describe the tumour suppressor (underactivity mutation - loss of function) path to cancer
- Normal cell
- Mutation event (inactivates tumour suppressor gene)
- No effect of mutation in one gene copy
- Second mutation event (inactivates second gene copy)
- 2 inactivating mutations functionally eliminate the tumor suppressor gene, promoting cell transformation (2 mutations: one on each one)
170
What are some proto-oncogene mutations that could turn proto-oncogenes into oncogenes?
- Deletion or point mutation in coding sequence
- Regulatory mutation
- Gene amplification
- Chromosome rearrangement
171
What happens with the deletion or point mutation in coding sequence proto-oncogene mutation?
Leads to hyperactive protein made in normal amounts
172
What happens with the regulatory mutation proto-oncogene mutation?
Leads to a normal protein being greatly overproduced
173
What happens with the gene amplification proto-oncogene mutation?
Leads to a normal protein being greatly overproduced
174
What happens with the chromosome rearrangement proto-oncogene mutation?
- Nearby regulatory DNA sequence causes normal protein to be overproduced
- Fusion to actively transcribed gene produces hyperactive fusion protein
175
What's an example of an overactive receptor?
A proto-oncogene that has experienced gain-of-function and is now activating cell division without its usual extracellular receptor which when binding to growth factors, would be active and trigger intracellular signalling
- Now the receptor doesn't know when it is active or not and triggers intracellular signalling without binding to growth factors
176
What's loss-of-function?
The brake restraining the cell cycle is gone
177
What's an example of a tumour suppressor gone bad?
- Rb/Retinoblastoma
- There's hereditary retinoblastoma and nonhereditary retinoblastoma
- Leads to tumours in the eye
178
What's a type of cancer that isn't bad?
- Benign or non-malignant tumours
- ex: skin tags (epidermal growths)
179
Does proliferation kill you?
Proliferation isn’t enough to kill you -> what’s bad is when the proliferation spreads
180
What's the difference between a benign and a malignant tumour?
A benign tumor will stay put but a malignant tumor (ex: in your gut) will change so much that it’ll escape out of the basal lamina envelope and go into your blood (they'll disperse)
181
What's Rb?
A transcription mutation inhibiter
182
Describe the process that leads to metastasis
- Cells grow as benign tumor in epithelium
- Cells become invasive and enter capillary
- Cells travel through bloodstream (fewer than 1 in 1000 cells will survive to form metastases)
- Cells adhere to blood vessel wall in liver
- Cells escape from blood vessel to form micrometastasis
- Cells colonize liver, forming full-blown metastasis
- These cells can go to other places in the body and colonize and grow
183
What's the critical prevention for cancer?
Preventative medicine -> you can stop most cancers if you catch them early on
184
What do we say is a microevolutionary process?
Cancer
185
How many copies of Rb does a normal healthy individual have?
- 2 copies of Rb in your genes (1 from mom and one from dad)
- If you’re born with only 1 inherited genetic mutation you’re fine
- But if you gain a mutation from two carriers not just one from mom or dad, this could lead to being born with cancer
186
What happens with hereditary retinoblastoma?
- Person has an inherited mutant Rb gene
- The occasional cell inactivates its only good Rb gene copy
- But excessive cell proliferation can lead to retinoblastoma
- Result: most people with inherited mutation develop multiple tumors in both eyes
187
What happens with non-hereditary retinoblastoma?
- Person has 2 good copies of Rb gene
- Occasional cell inactivates one of its 2 good Rb genes
- Occasional cell inactivates its only good Rn gene copy
- Excessive cell proliferation leading to retinoblastoma
- Result: only about 1 in 30,000 normal people develop one tumor in one eye
188
Most tumours are malignant or benign?
Benign, but some don't stay that way
189
Why is it hard to find a cure for cancer?
- Because cancer is a microevolutionary process
- Every cancer once it begins changes overtime
- 6 months later you’re dealing with a different cancer due to so many mutations
190
What's the multiple hit hypothesis about cancer?
Once a cancer cell loses control (through cell proliferation), additional mutations are more likely to occur
191
What kind of cells grow on the basal lamina (envelope around the tumour cells)?
Epithelial cells
192
What happens to tumor cells overtime?
- They change
- Cells die, and are replaced with new cells that are likely to acquire additional mutations
- As a result, the original tumour is replaced by a very different (and malignant) tumour
- This occurs throughout life (example: breast cancer)
193
After approximately how many mutations are you dealing with a new cancer?
Once you’ve gotten 4 mutations, you’re dealing with a new cancer
194
Breast epithelial cells must do what?
Divide throughout life
195
Through what does tumour regeneration occur?
- Via cancer stem cells
- Some cancer cells are “stem cells”, single cells that can regenerate the tumour
- Cancers will shed what are called cancer stem cells, which have the possibility to become yet another cancer
- STEM cells allow the cancer to act as if it’s not a muscle but bigger such as a stomach lining
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What's a promoter?
A region of DNA that initiates the transcription of a particular gene
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What's a transgene?
A gene that's transferred from one organism to another
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What's referential signalling in language and what are examples?
- Referential signals: Signals that contain information about the environment
- Chickadees can use referential signalling: they can indicate the size and how
dangerous a predator is by changing the
number of ‘D’ notes in their calls
- Vervet monkeys have different sounds for different types of predators
- Bees perform a “waggle dance” to indicate where a good food source is
- Referential signalling isn't exactly language because it can only be in the present and concrete
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What are examples of different referential signalling in vervet monkeys?
- Snakes: when someone makes the snake call, everyone looks down, and stands up bipedally
- Hawks: when someone makes the hawk call, everyone looks up and runs for the nearest bush
- Leopards: when someone makes the leopard call, everyone checks the trees and ground, runs out onto branches that
can’t support the leopard’s weight
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What's displacement?
- the ability to talk about something
temporally or spatially distant
- With language, we can talk about things that happen at a different time (the future, the past)
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In what animal do we find referential signalling and syntax but no productivity language?
- Bees
- Referential: can communicate where they came across a good food source as well as how good the food was (displacement)
- Syntax: The waggle dance has a clear structure or syntax
- Parts of the dance can be modified to indicate different information (distance, direction)
- Has a modifiable sequential structure
- Productivity: Bees don't make completely new signals with completely different
meaning (no productivity)
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What's the productivity characteristic of language?
- the creation of new signals
- We can make new signals out of existing signals
- Without this ability, we could not talk about all kinds of things today (everything from airplanes to the internet)
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What's the syntax characteristic in language?
Detailed structure or sequence that has rules
204
What are homologous traits?
Traits that arise from a common
ancestor
205
What are analogous traits?
Traits that are similar in function or
structure, but not because they come from shared ancestry (evolve independently)
206
In order to develop an eye, animals require what gene?
- PAX6
- control gene
- Regulates the expression of other
genes in a cascade during development
- In particular, PAX6 determines where an
eye will develop
- If you put it on the leg of an embryo, the
embryo will develop an eye there
- Wherever PAX6 gets turned on or expressed, the embryo will eventually develop an eye
- Mutations in the PAX6 gene result in individuals with small (or no) eyes
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Could other species evolve language?
Sure!
But, from current data, it doesn’t seem to have happened yet
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What's FOXP2 important for?
- Appears to be important for motor learning
- In songbirds, FOXP2 deficits result in poor song learning,
and the production of aberrant, garbled songs
- In bats FOXP2 may be important for echolocation, which requires a lot of sensory-motor integration but isn’t a learned vocalization
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Eyes are an example of what?
Convergent evolution
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What's convergent evolution?
- Comprised of analogous traits which are similar in function or structure, but not because they come from shared ancestry
- Things that are analagous are said to evolve independently, that is, without a shared ancestor
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What's the effect of age on developing cancer?
- The longer you live, the more cell divisions you have
- Since there’s more risk for more cell divisions, your risk for cancer keeps increasing as you grow
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What are R-tumours?
Come from “Stochastic” errors in DNA replication —> mutations
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What are D-tumours?
Mutations that come from genetics, environment
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What are animal adaptations that protect against cancer?
- Very large animals (lots of cells) -> leads to adaption of extra copies of proto-oncogene genes
- Very long lived animals (many replications) -> leads to extra copies of tumour suppressor genes
- Extremophile animals (ex: tardigrades) -> leads to extra copies of tumour suppressor genes and unique protective proteins
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What's the ultimate stem cell?
- A zygote (2 nuclei: egg nucleus and sperm nucleus)
- It has the capacity to generate >200 types of cells in the human body
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What does a 2-celled embryo lead to?
Both cells can form a human which will lead to identical twins
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What's the process of going from an embryonic stem cell to an adult stem cell?
- Totipotent cell
- Pluripotent cell
- Multipotent cell (adult stem cell)
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Sperm and eggs are what kind of germ cells?
- Haploid germ cells
219
What happens when the sperm fertilizes the egg?
The result is a diploid 1-celled embryo called a zygote
220
Human cells contain pairs of what?
- Homologous chromosomes (one homolog from mom and one from dad)
- Sperm and eggs have 1 copy of the genome
- Every cells in body except for bacteria cells has 2 chromosomes (one set from mom other from dad)
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What's the difference between genes and chromosomes with regards to alleles?
One gene = many alleles
One allele per chromosome
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Alleles are described as what?
“flavors” of one gene
223
The allele that leads to gain of function and has a functional transporter is?
Dominant
224
The allele that leads to loss of function and has a defective transporter is?
Recessive
225
What's CRISPR?
- Clustered Regularly Interspaced Short Palindromic Repeats
- a prokaryotic immune system
226
How do bacteria defend themselves from the invasion of viruses?
- Important for bacteria to remember the virus and protect themselves
- To protect: places a copy of gene into area
227
What's Cas9?
an enzyme that recognizes and cuts invading DNA or RNA into pieces
(specifically, DNA/RNA from viruses)
228
What were the CRISPR mechanism and Cas9 enzyme engineered for?
- To introduce custom genes into the DNA of any organism
- Gene Drive alters the inheritance of this new DNA from 50% to ~ 100%
229
What does the CRISPR-Cas9 do?
- Genetic scissors
- Molecular tool that can be used to make precise incisions in genetic material, making it possible to easily change the code of life
230
What can the CRISPR-Cas9 help with?
- In plant breeding, researchers can give plants specific characteristics, such as
the ability to withstand drought in a warmer climate
- In medicine, this gene editor is contributing to new cancer therapies and the first studies attempting to cure inherited diseases
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What's gene drive?
- Driving expression of any gene you introduce
- Based in the targeted insertion of a sequence of DNA (stored on a plasmid)
-> this sequence contains: 5’ H1 template DNA + The Cas9 gene + The guide RNA gene + The “payload gene” + 3’ H2 template DNA
- Once the Gene Drive sequence is inserted into the genome, it will express the Cas9 nuclease and guide RNA that cuts the chromosome between the H1 and H2 sequences
- The targeted insertion relies on DNA repair enzymes that use the plasmid DNA as a template for repairing the broken chromosomal DNA
- The modified chromosome is used as a template to repair the homologous chromosome - and chromosomes have the the gene drive system and “payload” gene
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What's the result of gene drive?
- All gametes carry the edited gene
- All offspring will edit the gene on the homologous chromosome
- Their gametes will carry the edited gene
- In a few generations, virtually every organism in the population has two copies of the edited gene (especially in places where population is high and where mating occurs frequently)
233
What's mendelian inheritance?
one gene = one trait
234
What does each daughter cell have to choose between independently of its sister?
a 50% probability of remaining as a stem cell and a 50% probability of commitment to differentition
235
Is the rest of the brain fooled by the false memory implanted in mouse?
Yes
- That explains how they get
a change in behavior,
because the areas that are
important for producing that
behavior are also tricked by
the false memory!
- Other parts of the brain important for
determining how to respond to scary or
dangerous stimuli also respond as though
the false memory actually happened
