Unit 4 Genetics, Evolution, Development & Plasticity Flashcards
(169 cards)
1
Q
What two factors influence everything you do?
A
Your genes and your environment
2
Q
What did researchers find about facial expressions in people born blind?
A
They were remarkably similar to those of their sighted relatives
3
Q
What does the term ‘Mendelian Genetics’ refer to?
A
Inheritance occurs through genes, units of heredity that maintain their structural identity
4
Q
What are the pairs of genes aligned along?
A
Chromosomes
5
Q
What is the classical definition of a gene?
A
Part of a chromosome composed of the double-stranded molecule deoxyribonucleic acid (DNA)
6
Q
What does a strand of DNA serve as a template for?
A
The synthesis of ribonucleic acid (RNA) molecules
7
Q
What type of RNA serves as a template for the synthesis of protein molecules?
A
Messenger RNA
8
Q
What determines the order of amino acids in a protein?
A
The order of bases along an RNA molecule
9
Q
what are the two ways genes can present as
A
- Homozygous
- Heterozygous
10
Q
What is a dominant gene?
A
A gene that shows a strong effect in either the homozygous or heterozygous condition
11
Q
What is a recessive gene?
A
A gene that shows its effects only in the homozygous condition
12
Q
How many genes contribute to variations in eye color?
A
At least 10 genes
13
Q
What are sex-linked genes?
A
Genes on the sex chromosomes (X and Y in mammals)
14
Q
What defines a female mammal in terms of sex chromosomes?
A
Two X chromosomes
15
Q
What is an example of a human sex-linked gene?
A
The gene that controls red-green color vision deficiency
16
Q
What are sex-limited genes?
A
Genes present in both sexes but active mainly in one sex
17
Q
What is mutation in genetics?
A
A heritable change in a DNA molecule
18
Q
What kind of mutation involves part of a chromosome appearing twice or not at all?
A
Duplication or deletion
19
Q
What does epigenetics study?
A
Changes in gene expression
20
Q
What can modify gene expression?
A
Various experiences and environmental factors
21
Q
What does heritability indicate?
A
The extent to which observed differences among individuals depend on genetic differences
22
Q
What is the difference between monozygotic and dizygotic twins?
A
Monozygotic twins share the same genes; dizygotic twins do not
23
Q
What evidence do researchers use to determine heritability?
A
- Comparison of monozygotic and dizygotic twins
- Studies of adopted children
- Examination of virtual twins
gene identification
24
Q
Fill in the blank: A dominant gene shows a strong effect in either the _______ or _______ condition.
A
homozygous, heterozygous
25
True or False: All RNA molecules code for proteins.
False
26
What can severe traumatic experiences in early childhood affect?
Methylation of many brain genes
27
What is a key role of enzymes in the body?
Regulate chemical reactions
28
What happens to the expression of certain genes during puberty?
Certain genes that had been almost silent become much more active
29
What is the effect of maternal malnutrition on offspring?
Alters the expression of certain genes to conserve energy
30
What is implied by any genetic similarity between behaviors?
Environmental influences
## Footnote
Behavioral differences suggest genetic influences.
31
What do studies of adopted children indicate about hereditary influence?
Tendency to resemble biological parents
## Footnote
Evidence is not always decisive due to prenatal environment.
32
What types of behaviors have researchers found significant heritability for?
* Loneliness
* Neuroticism
* Television watching
* Childhood misbehavior
* Social attitudes
* Cognitive performance
* Educational attainment
* Speed of learning a second language
## Footnote
Religious affiliation has not shown significant heritability.
33
What does heritability of a trait depend on?
The specific population
## Footnote
Example: Alcohol abuse shows moderate heritability in the U.S.
34
What is the candidate gene approach?
Testing hypotheses linking specific genes to behaviors
## Footnote
Example: Gene linked to serotonin transporter and depression.
35
What is a genome wide association study?
Examines all genes comparing two groups
## Footnote
Risks include false positives and misleading results in diverse samples.
36
What are some well-supported findings from behavioral genetics?
* Almost everything in psychology shows genetic influence
* Nothing in psychology has 100% heritability
* Heritability depends on many genes with small effects
* Stability of behavior over age is due to genetics
## Footnote
Few identified genes with major effects exist.
37
What are potential reasons for not locating strong links between genes and behaviors?
* Many genes exert small effects
* Microduplications or microdeletions
* Rare mutations with large effects
* Epigenetic effects
## Footnote
These factors complicate the understanding of genetic influences.
38
What is phenylketonuria (PKU)?
A genetic inability to metabolize phenylalanine
## Footnote
Can lead to brain development issues if untreated.
39
How can environmental interventions modify PKU?
Strict low-phenylalanine diet
## Footnote
Success shows that heritable traits can be modified.
40
What is the relationship between genes and behavior?
Genes produce proteins influencing behavior through complex interactions
## Footnote
Genes can influence behavior indirectly via environmental interactions.
41
What did Charles Darwin prefer to call evolution?
Descent with modification
## Footnote
Emphasizes changes without implying improvement.
42
What are the two questions about evolution?
* How did some species evolve?
* How do species evolve?
## Footnote
These address evolutionary relationships and mechanisms.
43
What is artificial selection?
Selecting individuals with desired traits for breeding
## Footnote
Used in agriculture and animal breeding.
44
What is a common misconception about evolution regarding the use of traits?
Use or disuse of traits causes evolutionary changes
## Footnote
This idea is rooted in Lamarckian evolution, which lacks evidence.
45
Does modern medicine stop human evolution?
No, evolution depends on reproduction, not just survival
## Footnote
Genes can still spread if certain individuals reproduce more.
46
What does evolution improve according to its definition?
Fitness
## Footnote
Fitness is defined by the number of gene copies that endure in later generations.
47
Does evolution benefit individuals or species?
It benefits the genes
## Footnote
Genes use individuals to reproduce themselves.
48
What is a misconception about lemmings and evolution?
Lemmings jump off cliffs to control population
## Footnote
This would disadvantage the 'self-sacrificing' gene.
49
histones
proteins that bind DNA into a shape that resembles a string would around a ball
50
what happens when Acetyl groups are add and removed within a cell (epigenetics - how does the experience modify gene expression)
added -> loosens dna and gene is turned on
removed -> tightens dna and gene is turned off
51
what happens when methyl groups are added and removed within a cell (epigenetics - how the experience modifies gene expression)
added: gene is turned off
removed: gene is turned on
52
methylation
biochemical process where Methyl groups are added to a molecule such as DNA/ When added to DNA the gene is turned off/removed gene is turned on
53
common misunderstandings of evolution
use/disuse changes traits (based on Lamarckian evolutionary theory - traits evolve only through inheritance genetic change)
Humans stopped evolving (evolution depends on reproductive success, not just survival)
Evolution = improvement (evolution is improved fitness, not necessarily moral or social betterment
Evolution favors species (false, evolution favors genes, behaviour that benefit gene carriers spread)
54
evolutionary psychology
focuses on how behaviors evolved (via natural selection)
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altruistic behaviour
an action that benefits someone other than the action (in humans - charity, in non humans, rare)
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explanations for altruism
kin selection, reciprocal alturism, and group selection
57
kin selection
selection for a gene that benefits the individuals relatives (bc they share your genes)
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reciprocal altruism
idea that individuals help those who will return the favour (people help those they see helping others)
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group selection
cooperative groups survive better than selfish/less cooperative ones
60
What are homeobox genes?
Genes found in vertebrates, insects, plants, fungi, and yeast that regulate gene expression and anatomical development.
## Footnote
They control body orientation and mutations can lead to deformities and brain disorders.
61
When does the human central nervous system begin to form?
At 2 weeks of embryo development.
## Footnote
The neural tube forms, leading to the development of the hindbrain, midbrain, and forebrain.
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What occurs at 7.5 weeks of embryo development?
Muscle movements start, limited to stretching muscles.
## Footnote
Spinal cord activity drives muscle movement before sensory organs are functional.
63
What is the weight of the human brain at birth?
350 grams.
## Footnote
By the end of the first year, the brain weighs about 1000 grams.
64
What areas of the cortex mature early?
Primary sensory areas, including vision and hearing.
## Footnote
These areas establish connections to the thalamus early in development.
65
Which part of the brain shows significant development in the first couple of years?
Prefrontal cortex.
## Footnote
It is involved in attention, working memory, and decision-making.
66
What is the adult weight range of the human brain?
1200-1400 grams.
## Footnote
This weight is reached after several years of development.
67
What is synaptogenesis?
The formation of synapses that give a neuron its distinctive properties.
## Footnote
It begins before birth and continues throughout life.
68
What is myelination?
The process by which glia produce insulating fatty sheaths that accelerate transmission in vertebrate axons.
## Footnote
It begins in the spinal cord and continues into adulthood.
69
What traditional belief did Cajal hold about neuron formation?
That vertebrate brains only formed neurons during embryological development or early infancy.
## Footnote
This belief has been challenged by recent findings.
70
Which brain area is known for forming new neurons in both birds and mammals?
Hippocampus.
## Footnote
New neurons support learning and memory formation.
71
What is the C-14 Radioactive Isotope Method used for?
To track the age of cells based on carbon-14 concentration in their DNA.
## Footnote
This method revealed insights into neuron turnover rates in different tissues.
72
What happens to neurons that do not receive nerve growth factor (NGF)?
They undergo apoptosis (programmed cell death).
## Footnote
NGF promotes the survival and growth of axons.
73
What is fetal alcohol syndrome (FAS)?
A condition resulting from prenatal alcohol exposure, leading to various cognitive and physical impairments.
## Footnote
It can cause thinner cerebral cortex and lasting effects into adulthood.
74
How does alcohol affect developing neurons?
It disrupts neuron proliferation, migration, differentiation, and synaptic transmission.
## Footnote
Alcohol alters neurotransmitter activity, promoting neuron death.
75
What is the role of neurotrophins?
They promote the survival and activity of neurons.
## Footnote
BDNF (brain derived neurotrophic factor) is an important neurotrophin related to depression.
76
What is the principle of neural Darwinism?
Competition among axons to establish appropriate synapses.
## Footnote
More appropriate synapses are strengthened while others are eliminated.
77
What did Rita Levi-Montalcini discover about neuron formation?
Muscles do not determine the number of axons formed, but rather how many survive.
## Footnote
This led to understanding that the nervous system overproduces neurons.
78
What are the effects of maternal stress on offspring?
Influences offspring's brain and behavior, leading to more academic and social difficulties.
## Footnote
Stressed mothers may groom less, resulting in fearful offspring.
79
What happens to early-stage transplanted neurons?
They fully adopt the properties of the new cortex location.
## Footnote
This shows the adaptability of neurons during development.
80
What did the ferret experiment demonstrate about sensory input?
It can guide the development and specialization of cortical areas.
## Footnote
Researchers rerouted optic nerves to auditory areas, showing functional plasticity.
81
How do adult neurons change shape?
Through growth, retraction, or disappearance of dendritic branches.
## Footnote
This plasticity allows adaptation to new experiences.
82
What is brain plasticity?
The nervous system can remodel in response to experience.
83
How do adult neurons change shape?
Particularly in peripheral dendritic branches.
84
What percentage of dendritic spines change within a month?
~6%.
85
What is linked to learning in the context of dendritic spines?
Changes in spines = synapse turnover.
86
What are the effects of enriched environments on rats?
* Developed thicker cortex
* More dendritic branching
* Improved learning.
87
What difference was observed between wild-caught rats and lab rats?
Wild rats had more neurons in visual areas, fewer in auditory areas.
88
What does stimulating environments promote across species?
Axon/dendrite sprouting.
89
What is a significant benefit of using a running wheel for rodents?
Boosts growth of axons/dendrites and learning.
90
How do enriched environments affect humans?
Effects are less clear; better outcomes seen in normal environments vs. minimal-care orphanages.
91
What is 'far transfer' in learning?
Improvement on unrelated tasks.
92
What is 'near transfer' in learning?
Improvement on similar tasks.
93
Is there strong evidence for far transfer?
No, evidence shows far transfer is weak.
94
What cognitive skills do brain puzzles improve?
Puzzle-specific skills, not general cognition.
95
What cognitive benefits have been associated with complex 3D video games?
Potential cognitive benefits after prolonged play.
96
What are the effects of general brain training?
Limited/temporary improvements.
97
What happens to the brain when sensory systems are impaired?
The brain can reorganize.
98
How do blind individuals demonstrate enhanced sensory attention?
Increased attention to touch and sound.
99
What is the outcome of tactile tasks for blind individuals?
They outperform sighted individuals.
100
What happens to the occipital cortex in blind individuals during touch-based tasks?
It becomes active.
101
What is the effect of music training on the auditory cortex?
Musicians show stronger auditory cortex responses (about 2x).
102
What brain changes are associated with musicians?
* Enlarged brain areas related to hearing and finger control
* Enhanced subcortical responses to music and speech.
103
How does early music training affect the brain?
Earlier training leads to greater effects.
104
What is focal hand dystonia?
A disorder where one or more fingers are in constant contraction.
105
What is a cause of focal hand dystonia?
Brain-based overlap in brain maps of fingers.
106
What behavioral traits are associated with adolescence?
* More impulsive than adults
* Prefer immediate rewards.
107
How does the prefrontal cortex relate to impulse control in adolescents?
It is less mature, correlating with impulse control.
108
What happens to cognitive abilities in old age?
* Memory and reasoning generally fade
* Loss of synapses.
109
What misconceptions exist about cognitive decline in older adults?
Not all older adults experience significant decline; many retain sharp cognitive abilities.
110
What protective factors can boost cognitive function in older adults?
* Exercise
* Engaging in mentally stimulating activities.
111
What happens to the hippocampus with age?
It shrinks, leading to memory declines.
112
What is the effect of blood transfusion studies on learning and memory in mice?
* Old to young: impairs plasticity and learning
* Young to old: improves dendritic spine density and learning.
113
stages in neuron development
proliferation
migration
differentiation
myelination
114
proliferation
Production of new cells, occurring mainly in the ventricles of the brain.
115
stem cells
undifferentiated cells that divide and produce daughter cells that develop more specialized properties)
116
migration
moving of cells
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differentiation
to develop the axon and dendrites, and synapses that give a neuron its distinctive properties
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synaptogeneis
formation of synapses
119
myelination
process by which glia produce the insulating fatty sheaths that accelerate transmission in many vertebrate axons
120
tectum
visual area of the brain
121
neural Darwinism
principle of competition among axons
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nerve growth factor
a protein that promotes the survival and growth of axons in the sympathetic nervous system and certain axons in the brain
123
apoptosis
programmed cell death
124
neurotrophins
chemical that promotes the survival and activity of neurons (i.e. NGF, BDNF)
125
DBNF
brain derived neurotrophic factor
126
gastrulation
crucial embryonic stage, errors here are fatal
127
fetal alcohol syndrome
a condition resulting from prenatal exposure to alcohol and marked by characteristics like: hyperactivity, impulsiveness, decreased alertness, varying degrees of cognitive impairment
128
what do the early, mid, and later stages of alcohol damage look like
early -> dirupts neuron proliferation (fewer neurons produced)
mid -> impairs neuron migration (neurons moving to correction location) and differentiation (how neurons develop functions)
later -> impairs synaptic transmission
129
how does alcohol prevent developing neurons from being stimulated
Alters NT activity and promotes apoptosis by inhibiting glutamate receptors (helps neurons stay active, neurons die due to decrease in excitation) AND enhancing GABA receptors (gaba is inhibitory, and slows activity, further suppresses neural activity)
130
how does alcohol continue to cause harm in the fetus after it has left the system?
○ Neurons adapted by building extra glutamate receptors (to compensate suppression)
○ When alcohol leaves, glutamate overexcites receptors
Causes excess sodium and calcium to flood cells, poisoning the mitochondria
131
far transfer
improvement on unrelated tasks
132
near transfer
improvement on similar tasks
133
What are common causes of brain damage?
Tumors, infections, exposure to radiation or toxic substances, degenerative conditions like Parkinson's and Alzheimer's.
134
What is a closed head injury?
A sharp blow to the head that does not puncture the brain.
135
What is the most common cause of brain damage in young people?
Closed head injury.
136
What does the duration of confusion and memory loss predict?
Strong predictor of long-term outcome.
137
What percentage of closed head injury cases require hospital treatment?
7-8%.
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What are the causes of damage after a closed head injury?
* Rotational forces that drive brain tissue against the inside of the skull
* Blood clots that interrupt blood flow to the brain.
139
How do woodpeckers avoid brain injury despite high-speed impacts?
* Use light taps before hard strike
* Hard strike is straight and controlled
* Rigid neck and spongy skull bones act as natural shock absorbers.
140
What implications do woodpeckers' adaptations have for humans?
Better helmet design, tuck chin to chest in crashes.
141
What is a stroke?
Temporary interruption of normal blood flow to a brain area, also known as a cerebrovascular accident.
142
What is the common cause of brain damage in older people?
Stroke.
143
What is ischemia?
Result of a blood clot or other obstruction in an artery.
144
What happens to neurons during ischemia?
They are deprived of blood and lose much of their oxygen and glucose supplies.
145
What is hemorrhage in the context of stroke?
Result of a ruptured artery.
146
What are the effects of hemorrhage on neurons?
Flooding with blood and excess oxygen, calcium, and other chemicals.
147
What is edema?
Accumulation of fluid that increases pressure on the brain and probability of additional strokes.
148
What is denervation supersensitivity?
Increased sensitivity to neurotransmitters by a postsynaptic neuron after loss of input.
149
What is the role of tissue plasminogen activator (tPA) in stroke treatment?
It is a drug that breaks up blood clots, improving outcomes for ischemia if administered quickly.
150
What challenges exist in determining if a stroke is ischemic or hemorrhagic?
Only an MRI can determine this, but time is limited for treatment.
151
What are some other treatment attempts for stroke?
* Decrease stimulation by blocking glutamate synapses
* Cooling the brain
* Antioxidants
* Antibiotics
* Albumin
* Treatments affecting the immune system.
152
What effects do cannabinoids have on stroke damage in animals?
Reduce stroke damage by reducing glutamate release, having anti-inflammatory effects, and altering brain chemistry protectively.
153
What is the general recovery process following a brain injury?
Surviving brain areas reorganize and increase activity.
154
What is diaschisis?
Decreased activity of surviving neurons after damage to other neurons.
155
What was the outcome of Feeney's experiment with rats and cats after cortical damage?
Amphetamine increased dopamine and enhanced behavioral recovery.
156
What is axon sprouting?
After a cell loses input from an axon, it secretes neurotrophins inducing other axons to form new branches.
157
What does denervation supersensitivity compensate for?
Lost input from active synapses.
158
What is the phantom limb phenomenon?
Continuing sensation of an amputated body part.
159
What can trigger phantom sensations in amputees?
Stimulation of adjacent body parts.
160
What is the significance of artificial limbs in relation to phantom pain?
They can help displace abnormal connections that cause phantom sensations.
161
What is the effect of therapy on recovery from brain damage?
It encourages learning to make better use of abilities that were spared.
162
What are deafferented limbs?
Limbs that have lost afferent (sensory) input but still have motor nerve connections.
163
What is a key implication for stroke recovery?
Forcing patients to use the weaker limb by preventing use of the normal limb.
164
What factors can make recovered behaviors vulnerable?
* Alcohol
* Exhaustion
* Stress
* Aging.
165
166
deafferented
lost afferent (sensory) input but motor nerves still connect to muscles in the limb
167
homozygous
having two identical gens for a given characteristic, identical genes on both chromosomes
168
heterozygous
different versions of a gene, unmatched pair
169
three types of genes
dominant, recessive, and intermediate
