Chapter 3 - Cells, Genes & Behavior Flashcards
(115 cards)
1
Q
Neurons
A
functional units in NS that enable us to receive info, process & act on it
- nerve cells
- 80 billion
2
Q
Glial Cells
A
Neuroglia or Glia
non-neuronal cells that provide multiple support functions
- 100 billion
3
Q
Nervous System is made up of? (2)
A
Neurons & Glia
4
Q
Neurons communicate via?
A
Electrochemical signals
5
Q
Nucleus
- (2) definitions
A
1) structure within cell body containing chromosomes
* house genetic material
2) cluster of similar cells that form functional grouping
* functionally related & densely packed
6
Q
Properties of Neurons (3)
A
- continously changing (plasticity)
- making new & losing old connections
- behavior produced by groups of neurons
- most have longevity
- not continuously replaced
7
Q
Most Neurons have longevity
- (2) exceptions
A
2 regions:
- Hippocampus
- Olfactory bulb
8
Q
Neurons: Basic Structure
- (3) main parts
A
1) Dendrites
2) Soma (cell body)
3) Axon
9
Q
1) Dendrites
- define
- (3) characteristics
- part(s)
A
branching extensions of neuronal membrane
- Unmyelinated (few exceptions - somatosensory)
- # per neuron varies
- gathers input (afferent part of neuron)
→ Dendritic Spines
10
Q
Dendrites are usually unmyelinated
- Exception?
A
Somatosensory Neurons
11
Q
1) Dendrites → Dendritic Spines
- function
- location of?
A
membranous protrusions from dendrite that typically recieve input from single synapse of axon (usual point of contact)
- increase SA
- where most synapses are found
12
Q
2) Soma (Cell Body)
- contains?
- functions? (2)
- (2) additional points
A
contains nucleus → genetic material (DNA)
- cellular functions (i.e. protein synthesis)
- processes input → integrates (excitatory & inhibitory)
→to determine whether or not to fire - can have synapses
- connects to axon via axon hillock
13
Q
Axon Hillock
A
specialized part of soma that connects to axon
- last site** in soma where **membrane potentials propogated** from **synaptic inputs** are **summated** before being **transmitted** to **axon
14
Q
3) Axon
→ define
→ (3)
→ components (3)
A
long, slender projection of neuron that carries msgs to other neurons
- 1 per neuron
- usually myelinated
- occurs with maturation
- sends output (carries info to other cells)
→ Axon Collaterals
→ Nodes of Ranvier
→ Terminal Boutons (Axon Terminals)
15
Q
Axon → Axon Collaterals
A
branches of axon
16
Q
3) Axon → Nodes of Ranvier
A
gaps between myelin sheaths (uninsulated)
- regenerates AP sent down axon
17
Q
3) Axon → myelin sheath
- forms when?
- functions (2)
A
Myelination occurs with maturation
- protects
-
speeds up communication
- allows saltatory (jumping) propogation of AP
18
Q
Nerve
A
bundle of axons in PNS
19
Q
Tract
A
bundle of axons in CNS
20
Q
3) Axon
→ Terminal Boutons (Axon Terminals)
A
distal terminal branches of axon that convey info to other cells
- site where electrical message converted to chemical & sent to next cell
21
Q
Synapse (Synaptic Cleft)
A
‘almost connection’ usually between terminal bouton of presynaptic neuron & dendritic spines of postsynaptic neuron
- site of information-transfer
→ permits passing of electrical/chemical signal to another neuron
22
Q
Types of Neurons (3)
A
different types of neurons are specialized for different types of functions
1) Sensory
2) Interneuron
3) Motor
23
Q
Types of Neurons (3)
1) Sensory
- axon
- cell body (soma)
A
recieves input from sensory receptors & sends to CNS
→ PNS
- axon projects from periphery (dendrites in PNS) to CNS via dorsal root
- cell body in dorsal root ganglion OR sensory cranial nerve ganglia
24
Q
Sensory Neurons → Somatosensory Neurons
- dendrites
- axon
- soma
A
brings sensory info from body into spinal cord
- few myelinated dendrites (in PNS) connect directly to axon, which projects into CNS
- soma off to side in dorsal root ganglia (PNS)
25
Types of Neurons (3)
2) **Interneuron**
**integrates** info from sensory neurons & conveys to **motor neurons**
**link** sensory & motor neural activity in **CNS**
26
Types of Neurons (3)
**3) Motor**
* cell body
* axon
sends **output** from CNS to effector organs
→ PNS (**lower** motor neurons)
* **soma & dendrites** in CNS (**spinal cord & brainstem**)
* axon projects into **PNS** forming spinal/cranial nerves → innervate **effector organs**
27
**Motor** Neurons → **Upper** vs. **Lower**
**Upper** → entirely in **CNS** & carry motor info to lower MN
**Lower** → project from **spinal cord** & innervate effector organs
28
**Specialization** of Neurons is reflected in their \_\_\_?
**Structure**, *which reflects function*
29
**Specialization** of Neurons is Reflected in **Structure**
* (3)
1) **#** of **dendrites**
2) **Size** of **Soma**
3) **length** of **axon**
30
Types of Neurons → **Sensory** Neurons
* structure
* function
* **bring** info to **CNS**
* ex) somatosensory
* **few** dendrites
* innervate small region to allow greater distinction of touch on different parts of body
Unipolar or Bipolar
31
Types of Neurons → **Interneurons**
* function
* structure
* examples (2)
link **sensory** & **motor** activity within **CNS**
**axons** branch into numerous **collaterals**
Examples:
* **Pyramidal** → throughout **cortex**
* **Purkinje** → in **cerebellum**
32
Interneurons → **Pyramidal Cell**
pyramid-shaped body
long axon
2 sets of dendrites projecting from **apex** & **sides**
33
Interneurons → **Purkinje** cells
**extremely branched** & fan-shaped dendrites
34
Types of Neurons → **Motor** Neurons
* function
* structure
send signals from **CNS** to **muscle**
**axons** project from **spinal cord/brain** forming **spinal/cranial nerves**
35
**Glia**
* provide support to neurons through? (5)
Insulation
Nutrients
Structural Support
Aid in Neuron Repair
Waste Removal
36
Glia
* Unlike neuron's characteristic of longevity...
Glia are **continuously** being **replaced**
37
Types of Glia (4)
1) **Ependymal** Cells
2) **Astroglia**/**Astrocytes**
3) **Microglia**
4) **Oligodendroglia** & **Schwann** Cells
38
Types of Glia (4)
1) **Ependymal Cells**
* location
* function
found on **ventricle walls** (within **choroid plexus**)
**produce** & **secrete** CSF
39
Types of Glia
1) Ependymal Cells
* **Hydrocephalus**
**blockage** of CSF (leads to hydrocephalus) → accumulation causing **↑ intracranial pressure**
* *obstruction in*
* *interventricular foramen, cerebral aqueduct or 4th ventricle → **non-communicating***
* *subarachnoid space due to prior bleeding or meningitis → **communicating***
treatment → 1 end of **shunt** (tube) inserted into blocked ventricle & other into vein, allowing CSF to drain into blood stream
40
Types of Glia
**2) Astroglia/Astrocytes**
* functions (5)
*star-shaped cells*
* **structural support** for CNS
* holds onto BV & neurons
* **nutrient & waste** bridge *between BV & neurons*
* part of **blood-brain barrier**
* feet hold endothelial cells closely
* allow certain substances across
* stimulate BV **dilation** → **enhance** brain activity
* Form **scar** to seal damage
41
Types of Glia
2) **Astrocytes/Astroglia**
* Scar formation to seal damage
* pros/cons
In **acute damage** phase → **beneficial** - seals off damaged area
* prevents cascade events from affecting other neurons *(further microbial infections/spread of cellular damage)*
In **long-term → harmful**
* scar tissue **prevents regrowth** & new connections
42
**Blood-Brain Barrier (BBB)**
* definition
* formed by?
* function
**highly selective permeable** membrane **seperating blood** from brain's **ECF** in CNS
* formed by **endothelial cells** connected by tight junctions
* encircled by **astrocyte feet**
* provide biochemical support
* *protect brain from substances in blood*
43
Types of Glia
3) **Microglia**
originate in **blood**
* **monitor** health of brain tissue → **immune system** role
* provide **growth** factors to **repair** damaged neurons
* **phagocytosis** - engulf foreign tissue & dead cells
→ *drawn to damaged area*
44
Types of Glia → 3) **Microglia**
* **PHAGOCYTOSIS**
p[rocess of engulfing **foreign** tissue & **dead** cells
45
Types of Glia
4) **Oligodendroglia** & **Schwann** Cells
support & **insulate** axons
form **myelin** **sheath** (glial coating surrounding & insulating axon)
46
Myelin Sheath
glial coating **surrounding** & **insulating** axon
* keeps info **localized & distinct**
47
Types of Glia → **Oligodendroglia**
* **function**
* axonal regeneration?
provide **myelin sheath** in **CNS**
* **Branches** form **segments** of myelin on adjacent axons
* **axons** do **NOT regenerate** in CNS
* *prevents by* *creating hostile, non-permissive growth environment*
48
Types of Glia → **Schwann** Cells
provide myelin sheath in **PNS**
* **facilitate regeneration** of **axons** in PNS
49
Multiple Sclerosis
NS disorder resulting from loss of/damage to **myelin** in CNS
* **cognitive & motor** effects
* since myelin can't be regenerated in CNS*
50
**Neuron Repair** in **PNS** →via **Schwann Cells**
* (4)
**14 - 35** days
i) peripheral axon **cut** → **dies**
ii) Schwann cells **shrink** & then **divide**, forming **glial cells** along **axon's former path** (secrete chemical signal)
iii) Neuron **sprouts** axons *(proximal segment - attached to cell body) →* 1 finds Schwann-cell path & becomes new axon
* distal segment **degenerates**
iv) Schwann cells **envelop** new axon to form **myelin**
51
**Regeneration in CNS**
* Why don't cells regenerate in CNS? (2)
Glial environment in CNS prevents regrowth
**_Astrocyte_** **scars** form (**chemical** & **physical**) **barrier** blocking regrowth
**_Oligodendroglia_** do NOT **form path** & **release chemical** that **repels** regrowing axons
52
Attempts at Regenerating Neurons (3)
1. **Placement** of **Tubes** across **Injured Area**
2. **Insertion** of **Immature Glial** Cells
3. Use of **Chemicals** to **Stimulate** Axon Growth
53
Attempts to Regenerate Neurons
## Footnote
**1) Placement of Tubes across Injured Area**
to provide path for axons
54
Parts of Cell Body (10)
1) Nucleus
2) Nuclear Membrane
3) Endoplasmic Reticulum (ER)
4) Mitochondria
5) ICF
6) Microtubules
7) Cell membrane
8) Lysosomes
9) Microfilaments
10) Golgi Bodies
55
Soma
1) Nucleus
contains genetic material (xsomes & genes)
56
Soma
2) Nuclear Membrane
double-layered membrane surrounding nucleus
## Footnote
*protective barrier*
57
Soma
3) Endoplasmic Reticulum (ER)
folded **extension** of nuclear membrane
* involved in **protein** & **lipid** synthesis
→ Smooth
→ Rough
58
Soma → Endoplasmic Reticulum
**Smooth** ER
lacks ribosomes
functions in **lipid & carbohydrate metabolism** & drug **detoxification**
59
Soma → Endoplasmic Reticulum
**Rough** ER
studded with **ribosomes**
site of **protein synthesis**
60
Soma
4) Mitochondria
**double-membraned** **organelle** that provides **cellular energy (ATP)**
* *gathers, stores & releases energy*
61
Soma
6) Microtubules
component of **cytoskeleton**
**structural** support & **pathway** for **synaptic vesicles**
62
Soma
7) Cell membrane
protective barrier surrounding entire neuron that seperates **intra**cellular & **extra**cellular components
63
Soma
8) Lysosomes
organelle enclosing **degradative enzymes**
* clean up waste within cell
64
Soma
9) Microfilaments
component of **cytoskeleton**
* **actin** filaments (thinnest)
* provide **structural** support
* cell motility
65
Soma
10) Golgi Bodies
membranous organelle
* **packages proteins** in vesicles *(to protect from degradation)* for **transport** to destination
66
Cell membrane → Structure
**phospholipid bilayer** that seperates **ICF** & **ECF →** *critical for neural functioning & protection*
* embedded **proteins** *control passage of substances*
* _Interior_: hydrophobic **non-polar** lipid tails
* _Exterior:_ hydrophillic **polar phosphate** heads
67
Cell membrane **regulates?**
* movement of substances in/out of cell
* [ions] & [water]
68
Storage of Genetic Materal
* location?
nucleus
69
Genes
**segment of** **DNA** that encode synthesis of particular **proteins**
* contained within **chromosomes**
70
Chromosomes
* # in human somatic cell
**double-helix structurse** that hold entire **DNA sequence**
* **23** pairs (**46** total)
71
**Deoxyribonucleic Acid (DNA)**
* made up of?
sequence of **nucleotides bases**
* Adenine (A)
* Thymine (T)
* Guanine (G)
* Cytosine (C)
72
Gene **Transcription**
* location
* process
occurs in **nucleus**
* **gene segment** of DNA **uncoils**
* 1 strand serves as **template** → attracts free-floating nucleotides
* **thymine** replaced by **uracil**
* complementary **mRNA** strand formed
* leaves nucleus
73
Translation
* process
**mRNA** carries **genetic code** out of nucleus to **ER**
* comes into contact with **ribosomes,** which move along mRNA strand
* **tRNA** drop off **AAs** encoded by consecutive sequence of 3 nucleotide bases, forming **polypeptide** chain
* forms **protein**
74
Translation
* **codon**
**sequence** of **3 bases** that **encodes** for **particular AA**
75
**Protein** vs. **Polypeptide**
**protein =** folded-up polypeptide chain
76
**Proteins →** _Packaging & Shipping_
* functions (4)
proteins
→ have various **functions**
* cell structures, enzymes, hormones, neurotransmitters
→ packaged in **golgi bodies** & shipped to **destination** along **microtubules**
77
Protein Destinations (3)
1) Incorporated into membrane
2) Remain within cell as **enzyme**
3) Excreted via **exocytosis**
78
Proteins **Embedded** in Cell Membrane
* ability?
* occurs when?
ability to change **shape**
* occurs in response to changes in:
* chemicals
* voltage
* touch/stretch (stimuli)
79
**Types of Proteins** in Cell Membrane (3)
1) Channel
2) Gated Channel
3) Pump
80
Types of Proteins in Cell Membrane
**1) Channel**
**opening** in protein embedded in cell membrane that allows **passage** of certain **ions**
81
Types of Proteins in Cell Membrane
## Footnote
**2) Gated Channel**
protein embedded in membrane that allows passage of substances through on **certain occasions**
* gates **open/close** in response to trigger
82
Types of Proteins in Cell Membrane
## Footnote
**3) Pump**
protein embedded in membrane that **actively** **transports** substances across
83
Genes do not _____ cause behavior
Genes do not **directly** cause behavior
84
**Genes** code for **proteins**, but other factors influence protein production (4)
1) **Gene** **pairs** → 1 expressed, other may not be
2) **Enzymes** change **mRNA** in nucleus
3) **Enzymes break-down** proteins to make more
4) Proteins **merge** to create different proteins
85
Behavioral Variation
* *flow chart*
**Genetic Variation**
→ Different **proteins**
→ Different cell **function**
→ Behavioral **variation**
86
Abnormal Behavior
* *****flow chart*
Abnormal **genes**
→ **defective** proteins
→ **impaired** cell function
→ **abnormal behavior**
87
Autosomes
**NON-**sex-determining xsome
pairs **1-22**
88
Sex Chromosomes
pair **23** of human somatic cells
89
Alleles
**alternate** forms of a **gene**
→ gene pair contains **2** alleles
* *pairs of xsomes → pairs of genes*
90
**Homo**zygous
having **2 identical** alleles for a trait
* *code for **same** protein*
91
**Hetero**zygous
having **2 different** alleles for a trait
92
**wild-type** allele
most **common nucleotide sequence** in a population
* **encodes** most common **phenotype**
93
Mutation
**alteration** of allele that **yields** a different version
**less frequently occuring** sequence of nucleotides
94
Heterozygous Alleles → **Dominant Allele**
member of gene pair that is **routinely expressed** as a **trait**
95
Heterozygous Alleles → **Recessive Allele**
member of gene pair that is **routinely unexpressed**
96
Phenotype
**physical & behavioral** **traits** expressed by organism
* depends upon **genotype**
97
Genotype
**genetic makeup** of organism (**genes**), which influences **phenotype** *(determines specific characteristics)*
* can refer to 2 alleles of particular gene
98
Codominance
traits of **both alleles** are expressed **completely**
99
Examples of Codominance (2)
**AB blood**
**Calico cats** (only female)
* X chromosome has color gene
100
Allele Disorders (2)
1) Tay-Sachs Disease
2) Huntington's Chorea
101
**Tay-Sachs Disease**
* caused by?
* results in?
caused by **recessive** allele on xsome 15
* causes **defective HexA** **enzyme** *that fails to break down lipids in brain*
* **lipids accumulate** in **neurons**
* results in **retardation, physical changes** (atypical growth) & death by ~ **age 5**
102
**Tay-Sachs Disease**
→ Normal **Carrier** x Normal
* possible outcomes & probability for offspring?
Normal **carrier → 50%**
Normal → **50%**
103
**Tay-Sachs Disease**
→ Normal **Carrier** x Normal **Carrier**
* possible **outcomes** & **probability** for offspring?
Tay-Sachs → **25%**
Normal → **25%**
Normal Carrier → **50%**
104
**Huntingtons Chorea**
* caused by?
* results in? when?
caused by **dominant allele**
* due to ↑ in # of **CAG repeats** on xsome **4**
* **\> 40**
* presents **middle age** *(earlier if ↑ repeats)*
* results in **motor & cognitive disturbances**
105
**_Huntington's Chorea_**
→ Normal **Carrier** x **Normal**
* possible outcomes & probability for offspring?
Huntingtons → **50%**
Normal → **50%**
106
**Huntington's Chorea**
→ **Carrier x Carrier** (will have if live long enough)
possible outcomes & probability for offspring?
Huntingtons → **75%**
Normal → **25%**
107
Relationship between **Genotype & Phenotype**
1 **Genotype** can produce many **phenotypes**
108
**Phenotype** is affected by? (2)
Gene Expression
Environment
109
Phenotypic Plasticity
capacity of one **genotype** to be expressed as more than one **phenotype** *when exposed to different environments*
* *even cloned animals have different phenotypes despite identical genotype*
110
Down Syndrome
**chromosomal** **abnormality** resulting in **mental retardation** & other **abnormalities**
caused by extra **#21 xsome**
111
Epigenetics
**differences** in **gene expression** related to **environment & experience**
112
Epigenetics
* How can **environmental factors** affect **protein production?** (3)
1) Histone Modification
2) DNA Modification
3) mRNA Modification
113
1) Histone Modification
genes may be:
* exposed via **acetylation**
* prevented from being exposed via **methylation**
**...** of tails of histones
which affects **transcription**
114
2) DNA Modification
DNA **transcription** into **mRNA** enabled/blocked
* **methyl (CH3)** groups bind to **CG base pairs** to **block** transcription
115
3) mRNA Modification
**mRNA translation** may be **enabled/blocked**
* binding of **ncRNA** to mRNA **prevents** translation
