Chapter 3 - Cell Function Flashcards
what was the debate in the early 1900s
about what is the smallest unit of human thought
camillo golgi’s view on the smallest unit of human thought
collection of fibers working together - no cell bodies - did the golgi stain
Golgi stain
used colour stain to discover neuron’s cell bodies - opposed his theory
santiago ramon y cajal view on smallest unit of human thought
each fibers is connected to cell - discovery of neuron
purpose of neuron
recieve and send signals from other neurons
what does a typical neuron have
lots of dendrites
dendrite purpose
recieve signals
axon
generate electrical impulse - AP
axon terminals
lots of terminals
send signals
very short or very long
myelin sheath
conserving energy and preserving energy loss
sensory neuron
most simple neurson
basic kind of neuron
bring information to the central nervous system
allows us to sense the world
pyramidal cells
cortical neurons/neurons in forebrain
majority of neurons in cerebral cortex
two types of cells in crebellum
purkinje cells and granule cells
cerebellum percentage of neurons
has 80% of the neurons that are in the brain
purkinje cells
heavy branches
very distinctive
only found in cerebellum
granule cells
most frequent in the brain
very small
not very developed
interneurons
is the connection between neurons
takes info from one and pass it on
they give feedback on whether to apply less or more forces to the spinal cord
can also change the signal
brain - interneuron - muscle
afferent neuron
coming into the brain
efferent neuron
exiting the brain
motor neurons
tend to be the largest neurons
longest axons
synapses directly against muscle fibers
number of neurons and gilial cells
equal number
types of gilial cells
astrocytes
microglial cells
astrocytes
no dendrites/axons
always around neurons
1st role: support neurons with nutrients out of the blood and into neuron
2nd role: maintain blood brain barrier
how do astrocytes maintain blood brain barrier
wraps itself around the artery - blood vessel cells and around the neuron
very tight junctions
protects brain from toxins in the blood while receiving nutrients
provide reinforcement too
microgilial cells two roles
1st - clear out debris - extracellular
2nd - main role - if there is damage in the brain - respond to it in repair role
ependymal cells
constantly producing cerebrospinal fluid
lines within spinal cord
two types of myelin
oligodendrocytes
schwann cells
oligodendrocytes
myelin in the CNS
formed by these cells
schwann cells
myelin in the PNS
also is able to rebuild the axons of neurons in the peripheral nervous system
how do schwann cells regenerate axons
when the axon dies, the schwann cells first shrink and then divide, forming gilial cells along former path, neuron sends out new axon and becomes a new axon, new myelin is also formed
why can’t myelin regenerate axon in the CNS
the enviroment is too complex and damage cannot be repaired
chromosomes 1-5
have lots of genes
chromosomes 6 and over
have fewer genes
purpose of proteins
allow for genotype to be expressed as a phenotype
purpose of genes
code for the conduction of diff types of proteins - source of a behaviour/trait
genotype
genetically coded info
phenotype
physical manifestations of genotype
the human genome project
trying to count the number of genes in the human body
contains less than 30K genes
DNA components
adenine, thymine, guanine, cytosine
dna component groupings
AT + GC
what determined which protein is produced
sequence of bases of each gene
bases code for amino acids which join to make proteins
genes to protein process
bases (ATGC) - amino acids (lysine) - protein
amino acids
an amino acid chain forms a protein
proteins
proteins are required to maintain a cell function
typically degrade within days
constantly being produced
process of making a dna
DNA - transcription - mRNA - translation - amino acid chain
transcription
copy of the DNA is made into mRNA
T is turned into U
happens within the nucleus
translation
reading the mrna AND every 3 bases into an amino acid - codon
happens in the ER
ribosomes read mRNA
creates amino acid chain
protein packaging and golgi bodies
proteins enter the golgibodies when they are wrapped in a membrane and given a shipping address
each protein package is attached to a motor molecule and moves along a microtubule to its destination
a protein may be incorprated into the membrane, remain within the cell, or excreted
function of protein
allows openings in the cell to let ions in
based on instructions of DNA
created as channels or pumps - sodium and potassium
wildtype genetic traits
how much of population shows that trait naturally - most people are right handed
what messes with wildtype genetic traits?
transgenic techniques - genes can be kicked in or out - silenced or introduced - fur colour in mice or genes for genetic disorders
tay sachs disease
inherited birth defect
appears 4-6 months after birth and results in severe brain damage and death about age 5
carried by reccesive gene
results of tay sachs disease as a reccesive gene disease
both parents need to be carried to have 25% chance of getting disease
one carrier will create a carrier but not expression
huntington’s disease
disorder that results in motor and cognitive disturbances - attack basal ganglia - form of dementia
dominant gene on chromosome 4
type of disease depends onw hen they develop it
huntington’s disease results based on dominant gene
will be eradicated since people choose not to have chidlren BUT
only needs one copy required to exhibit trait
one carrier or two carriers
mutation of FOXP2 gene
results in apraxia of speech
disruption of physical production of speech - motor outputs
someone can have the gene and have disruption but no cognitive deficits
gene augmentation
mutated gene (loss of function) is replaced by a different version can be introduced
introduce using a non-harmful virus
two types of gene therapy
gene augmentation and gene suppression
gene suppression
mutated gene (with gain of function defect) is replaced with inhibitory sequence with corrected gene
tumour
mass of cells that grows independetly of the body
associated with inactivation of tumor supressor genes - proteins
suicide gene induced
suicide gene
programmed cell death - inject gene into tumour - tumour is programmed to die
bubble boy story
not enough immune cells - reintroduced immune cells - which repopulated 0 most people with this gene are alive 0 severe combined immunodeficiency
potential complications to effective gene therapies
immunotoxicity
mutagenesis and risk of vertical transmission
excessive t-cell reactivity
immunotoxicity
adverse response to either viral delivery vector or augmented gene - might affect another aspect of functoining
mutagenesis and risk of vertical transmission
risk of mutation and passing that mutation on
excessive t-cell reactivity
most gene therapy is used for cancer
boosting immune system or t-cells might be overdone and kill good cells as well
alziehmers
overproduction of one protein which might suffocate other neurons and might destroy the good protein
epigenetic drift
drift of genetics due to enviromental and genetic differences
when does epigenetic drift happen
behavioural and genetic differences show up after twins start getting older - at any point of protein creation
3 types of epigenetic drift
histone modification
DNA modification
mRNA modification
histone modification
happens during the unravelling of DNA
a methyl group bind to the histones which are used to unravel dna for transcription
they either allow the dna to unravel or not - blocks the dna from unravelling - during transcription
DNA modification
happens after dna is unraveled and mrna is being created
methyl groups bind to CG base pairs - transcription
certain parts are not transcribed
mRNA modification
happens during translation when amino acids codons are being made
- original protein is not being produced - preventing translation
alterations of gene impacts
stable interactions in dna structure - altered gene expression - depressive symptoms
