Neuroscience Flashcards
(101 cards)
1
Q
What is prophase?
A
when the nuclear envelope breaks down and chromosomes start to be pushed around, pairs of homologous chromosomes form special bonds with each other
2
Q
What is metaphase?
A
homologous chromosomes align at middle of cell; random alignments
3
Q
What is an allele?
A
- They are “flavours” of genes that arise from mutations
- Also inherited by offspring
- They arise from mutations
- Functional transporter = dominant (ex: W)
- Defective transporter = recessive (ex: w)
4
Q
What is a totipotent cell?
A
can become any of the 200 types of cells in the body, ultimate stem cell
5
Q
What is regulating gene expression?
A
Turning a gene or a set of genes on or off
6
Q
What is a heat map?
A
Graphical representation of data where the individual values contained in a matrix are represented as colours
- Aid in comparison of very complex data
- In general, a heat map displays relative abundance
- Used to correlate gene expression as a function of:
Time
Location in the body (cell type)
Condition (health/disease)
7
Q
What is a pluripotent cell?
A
Can form many types of cells within the same lineage
8
Q
What is unipotent?
A
Can divide to produce more skin cells
9
Q
What are the two major types of stem cells?
A
Embryonic (ICM) - Forms all the cells of you - Trophoblast forms the placenta Adult - Tissue specific, not totipotent - Hematopoietic stem cells (blood cells) - Epithelial and epidermal stem cells (skin)
10
Q
Explain the promise of stem cell research
A
- Identify drug targets and test potential therapeutics
- Study cell differentiation
- Understanding prevention and treatment of birth defects
11
Q
How do you clone an organism?
A
- To clone an organism, it is not enough for the DNA to be identical
- All the necessary information in the DNA must be unlocked
12
Q
What is differentiation?
A
Cells decrease in potential as they grow- the fate the cells is already locked in
13
Q
Cloning is achieved through the process of what?
A
Nuclear transfer
14
Q
Explain the idea that information can be unlocked in G0
A
A method to unlock inaccessible information in DNA
15
Q
Forensic DNA analysis focuses on what?
A
On the differences between individuals and “Variable regions” at specific locations throughout the genome tend to differ between individuals
16
Q
What type of variability does forensic DNA focus on?
A
Short Tandem Repeats (STRs)
- An STR can have different numbers of repeats
17
Q
What is a polymerase chain reaction?
A
Allow fabrication of millions of copies of molecules
18
Q
STRs are amplified using what?
A
PCR
- The PCR primers attach to DNA sequences on either side of the repeats
- These regions do not vary between individuals
- The same primers can amplify the repeat region in any individual
19
Q
Everyone inherits how many copies of STR?
A
Two- one from mom and one from dad
20
Q
Forensic DNA analysis uses a standard set of what?
A
STR markers
- The human genome contains thousands of STR markers
- For forensic investigation, the FBI has chosen 13 of the most reliable STRs, plus a marker called AMEL, which detects gender
- Using a standard set of markers allows information to be shared at the local state and federal level
21
Q
Explain the evolution of DNA sequencing methods
A
1980s: Sequencing technology was labour intensive and used hazardous radioactive chemicals
1990s: More automated steps- sample preparation, sequence reading, etc.
- Additional improvements over the years cut cost and increased speed, allowing the HGP to finish under budget and ahead of schedule
Today: next generation sequencing technology
- faster and cheaper
Next step: the $1,000 genome
- The goal: sequence a human genome for $1,000 by 2014
Next generation sequencing technologies are very close to reaching this goal; it is now $100
22
Q
How can information from the 1000 genomes project be used?
A
Genetic testing
23
Q
What does CRISPR stand for?
A
Clustered Regularly Interspaced Short Palindromic Repeats
24
Q
What does CRISPR do?
A
CRISPR-Cas9 recognizes invading DNA or RNA and cuts it into pieces
• This process can be engineered to introduce new DNA at two cut sites
• Gene drive alters the inheritance of this new DN from 50% to ~100%
25
What does homologous mean?
Similar chromosomes
26
What does diploid mean?
pairs of homologous chromosomes
27
What is a DNA profile?
The number of repeats an individual has in both copies of all 13 STR markers, plus AMEL
28
What is gene drive?
A manipulation in the copy of genes in which the altered gene is always inherited
29
What is the significance of parasitism?
* It changes the structure of the brain
* Changes the connections between brain cells
* Changes the activity of the brain, which leads to changes in behaviour
30
What is a stimulus?
any input (light, sound, touch, taste, gravity, movement)
31
What is processing?
what you do with the information
- This can be very simple (like a reflex when you touch a hot pan)
- Or it can be complex (taking an exam)
32
What is behaviour?
anything you do in response to the stimulus
33
What is action potential?
an electrochemical wave, driven by the movement of ions along their electrical and concentration gradients
34
What is a neuron?
• They contain the same complement of organelles, cytoskeleton, DNA, etc.
• They have features that make them distinct
- They contain axons, dendrites and synapses
35
What are dendrites?
- Processes near the cell body
| - Receive input from other neurons
36
What are axons?
- Main conducting unit of the neuron
- Connects one cell to the next
- Conveys information by propagating an electrical signal (the action potential)
37
What are synapses?
- Used to communicate signals from one neuron to another
| - Where the axon of one cell connects to the dendrites of another cell is the synapse
38
Describe the concentration gradient in a neuron before action potential fires
- High concentration of sodium ions OUTSIDE the cell
- Low concentration of sodium ions inside
- This means we have a concentration gradient for sodium Na+ to go IN
- Sodium is an ion and it carries a positive charge
39
What is voltage?
a force that moves oppositely charged particles toward each other and similar particles away from each other
- To create voltage, you need to separate opposite charges
- Separating charge creates voltage or “potential difference”
- Voltage is a force, so that if you release the charges, they will move toward one another (this is how a battery works)
40
What is an electrical gradient?
positive and negative will come together
- Separating the charge with a cell membrane creates a voltage
- Adding a channel to the membrane allows charged particles to flow through, along the electrical gradient
41
What are Schwann cells?
They wrap around the axon
42
What is multiple sclerosis?
an autoimmune disease that results in damage to and breakdown of the myelin
43
What are neurotransmitters?
• They modulate a cell’s activity
• They basically affect the probability and timing of action potentials
- how much input will be needed to fire
- when the cell will fire relative to that input
- how many action potentials will be produced
44
What is multi-sensory integration?
The ability to pull together information from more than one sense at the same time
45
What is the thalamus?
a relay station for early sensory information
46
What is the cortex?
outermost part of the brain, layered structure, does higher-level processing
- Dendrites are in the layers of the cortex
- Axons appear white in brain scans (white matter)
47
What is electroencephalography (EEG)?
Uses electrodes to measure electrical activity along the scalp
- Pros: non-invasive, people can move around during recording
- Cons: it's hard to determine exactly where a change in activity happens
48
What is positron emission tomography (PET)?
Person eats radioactively labeled sugar, it gets picked up by active cells, and cells will give off radiation that can be detected by the scanner
- Pros: better resolution that the EEG and can see deeper brain structures
- Cons: you have to eat the sugar and you cannot move around much
49
What is functional magnetic resonance imaging (fMRI)?
Involves a scanner, but it uses magnets; the scanner applies magnetic fields to the brain , then measures the energy emitted by different brain areas
- because deoxygenated blood is more magnetic than oxygenated, areas that are more metabolically active emit different signals than less active areas
- Measures changes in blood flow → relies on the idea that cells that are working hard use more oxygen
- pros: offers reasonable resolution
- cons: participants can't move around much
50
What is electrophysiology?
Uses electrodes to measure action potential of neutrons; can measure one or hundreds at the same time
- it can help surgeons determine where speech and language areas are located and avoid them, but this is mostly done in animals
- high resolution
51
What is gene and protein expression in analyzing brains?
- Label mRNA proteins with radioactivity, dye, or antibodies attached to fluorescent or other tags
- Pros: enables you to look at a wide range of brain areas, expression within single neurons, changes in specific molecules
- Cons: have to take the brain out to look at it
52
Explain the importance of immediate early genes in brain analysis
- Types of proteins that are transcribed after there is a change in the brain
- Tells us whether a cell was active at a particular time, during a behaviour or response to stimulus
- If we label for other proteins, we can know what kind of cell it is
EXAMPLE: C-fos!
53
How do you know what a brain area does?
• Look at when it is active
- Increase the activity of cells
- Decrease the activity of cells
- Modulate the activity of cells
54
What is memory?
a behavioural change caused by experience
- In the brain, it’s a change in the number or strength of synaptic connections
- Changes in the activity of neurons or circuits can lead to changes in synaptic connections --> this can lead to the formation of memories
55
What is synaptic plasticity?
changes to the spines and synapses (happens EVERYWHERE in the brain)
56
What is episodic memory?
about autobiographical events, things that happened to you
| - Involve what, where, when
57
What is spatial memory?
use of geographic location and spatial cues
- Ex: London taxi drivers have a bigger hippocampus as the need to be able to navigate through the city by memory
- Thus, the hippocampus is larger in individuals that tend to do more spatial activity
- Removing the hippocampus impairs spatial learning and memory
58
What are place cells?
• Certain cells are active at certain positions
• As a group, place cells respond to an entire environment; each cell responds to just a tiny part
• You can determine the location of an animal on the maze based in the activity once you have to “place code”, the information that you get when you know how all the cells respond
- The code is complex
ESSENTIALLY, part of the code for navigating and remembering the environment
59
What is the goal of place cells?
- Verify that the hippocampus is indeed one place that stores episodic memory
- Get a very basic idea of how we know that memory is there and how that memory is encoded
60
What is conditioning?
A form of associative learning = learn to associate two stimuli with each other
61
What is fear conditioning?
To quickly associate a place with an experience and demonstrating that they remember the experience by displaying a conditioned response
- Immediate early gene expression (c-fos) after giving a stimulus produces a particular pattern of active cells
- These cells in the hippocampus are holding the memory of the place and the experience
62
How is c-fos used?
• C- fos is often used as a marker of neural activity (it's an immediate early gene)
- Cells express cFOS when they are more active
- More action potentials = more transcription and translation of cFOS = more cFOS expression
- it regulates the transcription of other genes
63
What is a transgene?
a gene that is transferred from one organism to another
| - tTA in our example
64
What is TRE?
the promoter for a very special gene for a protein called ChR2-EYFP
65
Explain the EYFP portion of ChR2-EYFP
- EYFP part is an enhanced yellow fluorescent protein
- Modified from green fluorescent protein found in jellyfish
- It fluoresces (glows) when you hit it with a particular wavelength of light
- Though don’t let the yellow part fool you, it actually tends to look more green
- This protein is just a way to tell if the system worked
66
Explain the ChR2 part of ChR2-EYFP
- It’s a channel rhodopsin
- Rhodopsin are channels that respond to light
- They open when light of a certain wavelength hits them
- These channels open and close when they are hit with light
- Unlike other channels, they are non-specific- they let any ion in
- They are from algae
67
What is doxycycline (DOX)?
- controls the labeling of active cells
| it blocks the tTA that’s produced, so there’s no labeling of cells with ChR2-EYFP (but there’s cFOS)
68
What is mCherry?
Like EYFP, but it's red
69
What is the function of the basal ganglia?
To help us learn motor tasks
70
What were the human characteristics 6-2 million years ago?
• During this time period, early humans began to walk upright and make simple tools
- Brain size increased, but only slightly
- Small canine teeth
-Bipedal (walked upright)
• Chimp characteristics:
- Grew rapidly after birth and reached adulthood earlier than modern humans
- Long, strong arms, curved fingers adapted for tree-climbing
- Apelike face proportions
- Small brain
71
What is the significance of "Lucy"?
She had both ape and chimp characteristics
72
What is bipedalism?
walking on two limbs instead of four
- Apes can do so occasionally, but they are posturally more suited for using four limbs
- For humans to do this required changes in the hips, lower back, and pelvis
73
What were the human characteristics 2 million to 800,000 years ago?
* Brain and body size increase
* During this time period early humans spread around the globe, encountering many new environments on different continents
* Greater use of tools and fire (though not yet controlled use)
* These challenges, along with an increase in body size, led to an increase in brain size
74
What is homo Erectus?
• First human species to live outside of Africa
• Oldest known early humans with human-like body proportions
- Longer legs, shorter arms relative to the torso
- Indicates adaptations for ground dwelling and loss of adaptations for tree-climbing
• Expanded brain case relative to the size of the face
• May have been one of the earliest humans to show reduced hair or fur
• The first big increase in brain size
75
How did the transition to eating meat occur for the homo Erectus?
- Brains are energetically expensive; you need a way to give them energy
- Transition to eating meat was important for growing and maintaining a larger brain
- This meant there needed to be a way to hunt that food
76
What is Homo neanderthalensis?
• Lived in the cold
- Shorter and stockier than us, thought to be an adaptation to the cold
• Made and used a diverse set of sophisticated tools
• Skilled hunters, also ate plants
• Controlled fire
• Lived in shelters
• Wore clothing
• Buried their dead
- Marked graves with flowers or offerings
• It is possible to study Neanderthal DNA (Neanderthal genome project)
77
What is homo sapien?
* Lighter skeletal build compared to earlier humans
* Less heavily developed jaws, with smaller teeth
* Less (if any) heavy brow ridges and prognathism of other early humans
* Skull recognition- a thin walled, high vaulted skull with a flat and near vertical forehead
78
When were there two “bursts” or big increases in brain size?
- The first occurred with the split between the austropithecines and the homonids
- Around the emergence of homo erectus
- The second was around the time of the emergence of the first homo sapiens
79
Brain size is related to what?
Body size
80
Why were homo Erectus significantly larger than ancestral hominids?
- Large size makes them better equipped to get food:
- Chase carnivores off of carcases
- Hunt animals by running them to heat exhaustion
- Dig deeply for tubers which are more energy rich than grasses
A better diet was critical to produce a large metabolically expensive brain
81
Why is cooking important?
Cooking is important for getting more calories out of the food, so it can increase the amount of energy available from food
82
What is the strongest evidence of habitual cooking?
- Stone hearths
- Clay cooking vessels
- Bones encircling patches of dark ground or ash
83
What was the result of the reorientation of the body?
Instead of holding the body at an angle from the hips to the head, the reorientation resulted in the torso and all of the organs resting vertically on top of the hips and pelvis
• This reorganization was significant not just for walking but also for childbirth
84
What is the result of upright walking?
- Results in a vertical shortening of the pelvis
| - Limits how wide the pelvis can be
85
What is the difference of brain growth between mammals and chimps?
• In mammals:
- The brain mostly stops growing after birth
• In chimps:
- The brain grows for longer after birth compared to other mammals
86
Describe the skull of great apes
not one solid piece of bone, but a number of large pieces of bone connected by more flexible tissue
• These connections between large bones are called sutures
- The soft spots are called fontanelles
- Before birth, the sutures and fontanelles are soft, which allows the skull and brain to be molded and squeezed a little as the head passes through the birth canal
- Then, after birth, these sutures solidify or fuse, resulting in a continuous, solid skull
87
What is the significance of sutures and fontanelles?
* Sutures and fontanelles enable chimps to have a larger brain than species where the skull can’t be squeezed
* Sutures and fontanelles plus continued growth after birth meant humans could have even larger brains
88
Why did see a plateau in brain size between 1.5 and 0.5 million years ago?
One hypothesis is that eventually the benefits of improving diet no longer offset the costs of increasing brain size
89
Explain the second growth in brain size
• One possibility is that this was due to intraspecies interactions
• Basically, as population sizes started to increase there was more competition for resources within a species
- Food, mates, good places to live, etc.
- More cooperation and alliances between individuals
• A larger brain can hold more cells, larger cells, and more connections between cells
• Cells are larger when they hold more DNA
• The human genome is pretty big, so it requires larger cells
• Having more cells and connections allows for more complex behaviour
90
What is vocal learning?
- Found in very few species (humans, cetaceans, hummingbirds, parrots, elephants, bats)
Requires sensory input
- Young animals need to hear examples of the sound
- If they don’t, they will produce abnormal sounds
Requires practice
- Young animals have to try to make the sound many times before they get it right
- They have to be able to hear themselves while they do it
- If they can’t hear, they will produce abnormal sounds
The brain areas (like the basal ganglia) that are important for this sort of learning are similar across species and similar to brain areas that you need for learning other “motor” tasks
91
Explain referential signalling
- Signals can contain information
- Ex: animals have different sounds for different types of predators
- With language, we can talk about things that happen at a different time (the future, the past)
92
Explain syntax
- There are rules or principles governing the structure or sequence of communication signals
- Once you know the rules, you can change content
(Ex: once you know the rules for making a sentence in English, you can make all kinds of sentences with different words and meanings, following the same structure)
93
Explain productivity
- We can make new signals out of existing signals
- Means that language isn’t finite but can increase to incorporate new things
- Without this ability, we would have much more difficulty talking about all kinds of things today (everything from airplanes to the internet)
94
What does language involve and allow for?
- Displacement: the ability to talk about something temporally or spatially distant
- Syntax: a detailed structure or sequence that has rules and allows productivity
- Productivity: the creation of new signals
95
What are homologous traits?
they arise from an ancestor
96
What are analogous traits?
similar in function or structure, but not because they come from shared ancestry
97
How do we determine whether something is convergent?
by looking at the phylogeny
98
What is FOXP2?
an ancient control gene found in a wide array of species
• It’s not just in humans, it’s not just important for vocal learning, but possibly for motor learning, but doesn’t appear to be a language gene
99
How does GABA inhibit action potential?
- It makes the inside of the cell more negative (ex: -90mV) so that the cell will need a stronger input to fire
- GABA's a chloride channel, so Cl- flows into the cell
100
What is Hebb's Law?
Neurons that fire together wire together. The dendritic spines can change in size. They grow when neurons fire at the same time regularly, and they shrink when they stop happening at the right frequency.
101
What is convergent evolution?
the process whereby organisms not closely related independently evolve similar traits
