Module 2 - Early Development Process Flashcards
Each one of us originated from
two germ cells – a sperm and an ovum.
Germ cells are produced through
meiosis: the cell division process that results in a germ cell containing 23 chromosomes (not to be confused with mitosis).
Females are born with all of their ___________, whereas males make ___________ ________________
ovum, sperm continuously.
Meiosis involves two cycles of cell division called
meiosis 1 and meiosis 2
Sex cells are also known as __________
gametes
Each cycle of meiosis involves the same four phases as mitosis
PMAT. Just like mitosis the parent cell copies its DNA before cell division begins so each single stranded chromosome becomes double-stranded.
In prophase 1 the chromosomes condense and join together in pairs (one from father and one from mother). Genes are swapped in a pair called crossing over.
Metaphase 1 - pairs of chromosomes line up in the middle of the cell. Fibres attach the chromosomes to two bodies on opposite sides of the cell.
Anaphase 1 - the fibres seperate the pairs
Telophase 1 - two nuclei form and then the cell splits into two cells, each with 23 double-stranded chromosomes
Meiosis 2:
Each cell will divide again to form 4 cells with 23 single-stranded chromosomes
Prophase 2 - chromosomes condense and the nucleus breaks down
Metaphase 2 - the chromosomes line up in the middle of the cell.
Anaphase 2- Fibres pull single-stranded chromosomes apart
Telophase 2 - nuclei form and finally, the cells divide
The 4 cells produced by meiosis are genetically …
different to each other and to the original cell. This genetic variety explains why children can look and behave so differently from one another
During conception, how many sperm are released into the female ?
an average of 500 million (!!!)
sperm must swim for 6-7 hours to reach their destination
only about 200 sperm actually get close to the egg
A fertilized egg is known as
a zygote (at this point prenatal development has begun. )
Prenatal development is broken into 3 main stages:
The germinal period - weeks 0-2
the embryonic period - weeks 3-8
and the fetal period. - weeks 9 - birth
The first two weeks of prenatal development are known as
the germinal period. During this time, the zygote is rapidly dividing.
Day 1 - fertilization
Day 2-4: cell division takes places
Day 4-5: blastocyst reaches uterus
(Approximately 4-5 days after fertilization, the zygote enters the uterus from the fallopian tube. The zygote is now referred to as the blastocyst – it forms as a hollow ball of cells and will implant into the wall of the uterus.)
Day 5-9: Blastocyst implants
The germinal period comes to an end when the blastocyst is fully embedded, which takes about one week.
What prenatal development period lasts from implantation to 8 weeks?
embryonic period.
-cell differentiation begins
-beginnings of all organ systems are forming.
-Embryonic development follows a cephalocaudal pattern of development, meaning that areas near the head tend to develop first.
-By the end of the embryonic period, all bodily systems are functioning.
Three layers of cells differentiate
Ectoderm: The ectoderm will become the nervous system, nails, teeth, inner ear, eye lens, and epidermis.
Mesoderm: The mesoderm will become muscles, bones, circulatory system, and skin.
Endoderm: The endoderm will become the digestive system, lungs, urinary tract and glands.
At what stage of prenatal development does the neural tube form?
Embryonic period.
The neural tube - the precursor to the Central Nervous System.
The neural tube is created when the ectoderm folds in on itself, creating a u-shaped groove.
What is the embryo’s support system?
- the amniotic sac
- the placenta.
What are the functions of the placenta?
allowing nutrients, oxygen, and waste to pass through, while at the same time preventing maternal blood from mixing with the blood of the developing embryo.
When does the zygote enter the uterus from the fallopian tube?
Approx 4-5 days after fertilization (zygote is now referred to as the blastocyst)
What is the amniotic sac?
a liquid-filled sac in which the embryo floats, helping to protect it and maintain a constant temperature.
When does The fetal period begin?
at the end of the 2nd month and lasts until birth.
What happens during the fetal period of development?
development continues to be rapid and cephalocaudal in nature.
11-12 weeks, the fetus starts to become more active (spontaneous movements, reflexes) although movements are not felt by the mother until the fetus becomes larger, usually around 16 weeks.
20 weeks, the fetus starts to have facial expressions and begins putting on weight.
A premature birth at 20-22 weeks old has a chance of survival with significant medical intervention. However, 23 weeks is considered the age of viability, or the point at which the brain and lungs are developed enough for survival without major medical intervention.
What happens when the blastocyst becomes implanted in the uterine wall?
Begins to differentiate.
1st - into an inner cell mass that becomes the embryo
and outer mass that becomes the organism’s support system
Then the inner cell mass differentiates into several layers that will form various systems of the body
Then a fold in the top layer develops into the neural tube
What does the neural tube become?
One end of the tube will become the brain and the other the spinal cord.
The fetal experience includes
movement
sensory experiences
learning
Fetal behaviour - movement helps…
promote muscle development. Interestingly, there are large individual differences in prenatal activity, with these differences continuing into infancy. In other words, an active fetus is likely to become an active newborn.
Fetal behaviour - sensory experiences…
A fetus experiences some degree of sensory input from all five senses, although visual input is minimal.
Since a fetus can move around, it can experience tactile sensations such as kicking the walls of the uterus.
Amniotic fluid contains both odours and flavours (related to what the mother ingests), which a fetus can smell and taste. Researchers suspect that this may be one way in which cultural flavour preferences are transmitted.
A fetus can hear the world around them. This includes both the maternal world (e.g., mom’s heartbeat) and the outside world (e.g., voices of their family members).
Fetal behaviour - Learning…
When discussing fetal learning, we are only considering learning in its most simple form - habituation and dishabituation.
In other words, this essentially allows researchers to examine whether a fetus gets “bored” of a stimulus and if interest peaks when the stimulus is changed.
Research suggests that the nervous system of a fetus is developed enough to engage in this type of basic learning (e.g., they habituate to repeated stimuli). A fetal brain, however, is not yet developed enough to engage in more complex forms of learning.
Meiosis
cell division that produces germ cells
Ectoderm
the outermost layer of cells of an embryo in early development, which includes nerve cells
Mesoderm
the middle layer of cells of an embryo in early development, which includes the bones
Endoderm
the innermost layer of cells of an embryo in early development, which includes the lungs
Amniotic sac
a transparent, fluid-filled membrane that surrounds and protects the fetus
Placenta
a support organ for the fetus that consists of semi-permeable membrane
Germinal Period
- Blastocyst develops
- period ends at implantation
- begins at fertilization
Embryonic Period
- Neural tube develops
-Weeks 3-8 - 3 layers of cells form during this period
Fetal Period
-A premature infant may survive is born during this period.
- The mother will begin noticing movements during this period.
-Main feature of this period is weight gain
What is a teratogen?
is anything that has an adverse impact on development
What are examples of teratogens?
Chemicals
Medications
Recreational Drugs
Alcohol and Nicotine
Some Viruses and Bacteria
Maternal Health
The impact that a given teratogen will have on a developing fetus depends on many factors, including:
Type of Teratogen
Dosage
Duration of Exposure
Timing of Exposure
Genetics of the Mother
Genetics of the Fetus
Most infamous teratogen
Thalidomide, a medication that was approved for pregnant women without proper testing. Thalidomide resulted in serious birth defects for newborns who were exposed in utero.
Teratogen - alcohol
Germinal Period - organ system have not yet started to develop, mild alcohol consumption is unlikely to result in major birth defects
Embryonic period - major organ systems are rapidly developing. Exposure to teratogens during this period can cause major structural abnormalities. Exposure to alcohol can have significant impact on CNS.
Fetal Period- teratogen exposure during this period is more likely to result in physiological defects or minor structural abnormalities.
**The more mothers drink, the more likely it is to have an effect on their child; however, some babies will be unaffected due to their mother’s and/or their own genetic endowments.
Why are Major structural defects less likely to happen in the fetal period?
Because the basic organ systems are already in place.
what is one of the leading causes of preventable birth defects and developmental disabilities.
Alcohol.
But, not all pregnancies with such exposures will result in birth defects. First, there is a dose-response relationship between exposure to teratogens like these and the likelihood of negative outcomes. In other words, the higher the dose, the greater the likelihood of negative outcomes. Second, both maternal and fetal genetic susceptibilities (e.g., variation in the rate a drug will be metabolized) influence the final outcome.
The second most common drug used during pregnancy
Cannabis
maternal cannabis use during pregnancy has adverse impacts on children across development. Longitudinal research indicates that children exposed to cannabis early in development are at a greater risk for attention deficits, increased hyperactivity, and increased likelihood of substance use.
While this is likely to continue to be an active area of research, it is important to note that there is no evidence that there is a safe amount of cannabis exposure for a developing fetus.
Are sushi and chicken pox considered teratogens?
Sushi - no
Chicken pox (Varicella) - yes.
What two things contribute to development
both genes and the environment contribute to development. Nature versus nurture is no longer a debate.
What represents the “nature” factor when it comes to development
genes
What carries all of the “instructions” for making a person, which are packaged in genes.
DNA (deoxyribonucleic acid)
genes code for ____________, NOT for _____________
proteins, specific behaviors
What is the key ingredient that determines a cell’s characteristics and functions.
Proteins
Cells contain different forms of the same gene called
alleles.
This “back up copy” is helpful to ensure proper development.
What is responsible for most human traits?
polygenic inheritance
although every cell contains all genes, only some….
only some genes are expressed, and only some genes result in observable characteristics
Genotype
The set of genes that an organism carries
Phenotype
Expressed characteristics, influenced by genes and environment.
Ex: a baby has brown eyes.
most human traits, including eye colour, are the result of polygenic inheritance.
What controls where and how much protein is made by a gene, effectively turning the gene “on” or “off”?
Epigenetic “markers”
This occurs naturally during prenatal development when cells are differentiated (e.g., one cell becomes a brain cell while another becomes skin)
Identical twins originate from the same…
DNA
Epigenetics
The study of how DNA interacts with a multitude of smaller molecules found within cells, which can activate and deactivate genes
Genes in DNA are expressed when they are…
read and transcribed into RNA, which is translated into proteins by structures called ribosomes.
What mostly determines a cell’s characteristics and function?
Protein
What can boost or interfere with the transcription of a specific gene?
Epigenetic changes.
The most common way interference happens is that DNA or the proteins it is wrapped around gets labelled with small chemical tags.
The set of all the chemical tags that are attached to the genome of a given cell is called the epigenome.
How do epigenome’s inhibit gene expression?
Some of these, like a methyl group, inhibit gene expression by derailing the cellular transcription machinery or causing the DNA to coil more tightly, making it inaccessible. The gene is still there but it is silent.
How do chemical tags boost transcription?
Some chemical tags will unwind the DNA, making it easier to transcribe, which ramps up production of the associated protein.
Can epigenetic changes survive cell division?
Yes.
This means they can affect an organism for the rest of its life.
Epigenetic changes are part of normal development.
The cells in an embryo start with…
one master genome.
As the cells divide some genes are activated and others inhibited.
Approximately how many cell types are in our body
200 (they have essentially the same genome, but its own distinct epigenome)
The chemical tags that turn genes on and off can be influenced by factors including…
diet, chemical exposure, and medication. The resulting epigenetic changes can eventually result in disease if for example, they turn off a gene that make a tumor suppressing protein.
What is part of the reason why genetically identical twins can grow up to have very different lives.
Environmentally induced epigentic changes
As twins get older, their epigenomes diverge, affecting the way they age and their susceptibility to disease.
Can social experiences cause epigenetic changes?
Yes.
Ex: mother rats not attentive enough to pups, genes in the babies that helped them manage stress were methylated and turned off. And it might not stop with that generation.
Most epigenetic marks are erased when egg and sperm cells are formed, but researchers think that some of those imprints survive, passing those epigenetic traits onto the next generation.
Are epigenetic changes permanent?
Not necessarily. A balanced lifestyle that includes a healthy diet, exercise and avoiding exposure to contaminants may in the long run create a healthy genome.
Behavioural genetics
the study of how nature and nurture contribute to behaviour.
Specifically, behavioural genetics tries to determine how much variation in behaviour is the result of environmental versus genetic factors.
Twin studies
compare monozygotic (identical, 100% genetic similarity) twins to dizygotic (fraternal, 50% genetic similarity) twins.
Researchers typically assume that the twins were raised in the same environment. This is one reason why dizygotic twins are used instead of siblings, as dizygotic twins have more similarity in their environment (starting from the womb!).
**If correlation on a given trait is higher for monozygotic twins than for dizygotic twins, researchers can assume that there is a genetic contribution to the behaviour.
adoption studies
Look to see if offspring become more similar to their biological parents or to their adoptive parents.
If they become more similar to their adoptive parents on a given trait (e.g., reading ability), we can assume there is an environmental contribution.
On the other hand, if the children become more similar to their biological parents on a given trait (e.g., shyness), we can assume there is a genetic contribution.
heritability of traits
A statistic looking at the proportion of variance in a trait that is due to genetics. the percentage of variance in a population due to genes.
Measured at the population level. Not individuals.
Heritability is abstract. Tells us nothing about specific genes or environmental factors that contribute to behaviour.
Heritability operates in context. Genetics to play a stronger role with environments are stable, but the opposite can be true for disadvantaged environments.
Heritability estimates range from 0-1
0 means the variation in a trait is completely due to environmental factors.
1 means that 100% of the variation in a trait is completely due to genetic factors.
Genes code for
Protiens
Behavioural Genetics
The study of how nature and nurture contribute to behaviour
Epigenetics
The study of external modifications to DNA that turns genes “on” and “off”.
Twin studies
Research design that compares monozygotic to dizygotic twins.
Adoption studies
Used to examine whether offspring become more similar to biological or adoptive parents
Key processes of brain development
Neurogenesis
Neural Migration
Myelination
Synaptogenesis
Synaptic Pruning
Neurogenesis
Begins 3-4 weeks after conception, generally ends by weeks 18-20
Neurogenesis is the process through which new neurons are formed in the brain.
At its peak, 250,000 neurons are formed each minute. Prenatal neurogenesis is essentially complete by the 18th week, but it continues in some areas of the brain throughout life. Adult neurogenesis especially depends on the environment - it is now considered a normal part of healthy development, but can be inhibited by risk factors like stress.
Neural Migration
6-24 weeks after conception
Neural migration is the process by which neurons migrate, or move, to their adult location in the brain. Neurons migrate using both active and passive movement – some actively propel themselves, while others are carried along passively.
Myelination
3rd trimester-adulthood
Once in their final destination, neurons continue to grow and differentiate.
They also develop their myelin sheath – myelination is the process by which the myelin sheath (fatty sheath) forms around the axons of neurons.
The myelin sheath increases the speed of neural transmission and increases information-processing abilities in the brain.
Synaptogenesis
3rd trimester-adulthood
Once grown and developed, neurons start “talking” to each other through synapses.
Synaptogenesis is the process through which neurons form synapses with other neurons, resulting in trillions of connections.
Synaptic Pruning
Occurs throughout development, with bursts in early development and during adolescence
Synaptic pruning is a normal developmental process through which certain synapses are eliminated.
About 40% of the synapses that develop are eventually eliminated. Pruning occurs in different areas of the brain depending on development.
gray matter becomes less dense as the brain matures. The prefrontal cortex, which controls executive functioning and long-term planning, is the last to mature.
The saying “use it or lose it” truly applies when it comes to
Synaptic pruning
Why does pruning happen?
it is an evolutionary advantage to have a changeable brain – this allows organisms to adapt to their environment and survive in changing conditions.
Plasticity
Plasticity reflects the capacity of the brain to be affected by experience.
Experience-expectant plasticity
involves normal wiring of the brain and occurs in part from typical, expected experiences.
For example, hearing sounds and language is an expected part of development, and helps to develop associated brain areas. If this doesn’t happen, these brain regions do not develop in typical ways and will be taken over by other sensory areas.
Relatedly, experience-expectant plasticity is associated with the concept of sensitive periods.
Ex: the infant brain is wired to be responsive to language. If an infant is not exposed to language early in development, it is much more difficult for language capacities to develop in the brain
Experience-dependant plasticity
refers to the process by which neural connections are created/reorganized based on an individual’s personal experience
This type of plasticity is related to learning and memory and occurs throughout the lifespan.
Ex:, London taxi drivers have highly developed hippocampi
Human interactions are complex and can be involved in both kinds of plasticity
Infants instinctively attempt to elicit attention from adults. This stimulates neurodevelopment and helps the child learn from the world around them in species-expectant ways. In other words, infants expect adult interactions to develop cognitive, social, and emotional connections in the brain.
However, interactions between all infants and their caregivers are not equal. For example, higher quality (e.g., stable, predictable, attentive, warm) interactions enhance brain connections moreso than lower quality interactions. Thus, depending on what exactly is occurring in these parent-child interactions, a child’s brain will organize in different ways.
Neurogenesis
The process through which new neurons are formed in the brain.
Neural Migration
The process by which neurons move to their adult location in the brain.
Synaptogenesis
The process through which neurons form synapses with other neurons
Prenatal development occurs through 3 stages:
germinal (zygote), embryonic, and fetal.
Exposure to teratogens can negatively impact prenatal development. The likelihood of negative outcomes depends on…
many factors related to the teratogen, as well as the mother and developing fetus.
While all psychological traits have a heritability component (due to genetic factors), genes do not account for the full picture. What further influences development?
Environments further influence development and gene expression through epigenetics.
Hazards to prenatal development
-spontaneous abortion/misscarriage
-teratogens (drugs, environmental pollutants)
-Maternal factors (age, nutrition, disease, emotional state)
The human brain begins to develop in the womb and continues to develop over the life course in what ways?
experience-expectant and experience-dependant ways.
What did Dr. Noble and her team find?
lower family income was linked with smaller cortical surface area, especially in brain regions involved in language and cognitive control abilities.
Epigenesis
The emergence of new structures and functions in the course of development (modern form of epigenetics)
epigenetics
study of how DNA interacts with a multitude of smaller molecules found within cells, which can activate and deactivate genes
gamates/germ cells
-singel cell that resulted from the union of two cells - a sperm and an egg.
-they only contain 1/2 the genetic material found in other cells
-produced via meiosis
Meiosis
A form of cell division in which the eggs and sperm receive only one member from each of the 23 chromosome pairs contained in all other cells of the body
Largest human cell
Egg.
But sperm is among the smallest
Spontaneous abortion
Male fetuses are more susceptible to spontaneous abortion than females in both the 1st week and last several weeks of pregnancy
Female fetuses more susceptible in weeks 10-15
Male fetuses
more likely to experience fetal distress at birth
higher mortality rates for boys
More sensitve to teratogens
More likely to die from SID and have higher rate of developmental disabilities (attention disorders and Autism)
Female fetuses
Less likely than males to survive early gestation
Zygote
fertilized egg
4 major development processes of zygote transformation
1) Cell division
2) cell migration
3) Cell differentiation
4) Death - apoptosis (cell suicide)
Embryonic stem cells
embryonic cell that can develop into any type of body cell
All human fetuses, regardless of genes they carry can develop…
either male or female genitalia
If androgens are absent, female genitalia develops.
Source of androgens is male fetus itself (fetus influences own development)
At what stage do monozygotic (identical) twins most often originate?
Around 4th day after conception, when the cells arrange themselves into a hallow sphere with a bulge of cells, called the inner cell mass, on one side.
Dizygotic (fraternal) twins occur when…
two eggs happen to be realsed from the ovary into the fallopian tube and both are fertilized (only half genes in common)
Inner cell mass is initially how thick?
A single layer, but during second week it folds itself into 3 layers:
top - becomes nervous system, nails, teeth, inner ear, lens of eyes, outer surface of skin
middle - becomes muscles, bones, the circulatory system, inner layers of skin
bottom - becomes digestive system, lungs, urinary tract and glands
Cephalocaudal development
the pattern of growth in which areas near the head develop earlier than areas farther from the head.
What is related with children age 10 being more behaviourally inhibited?
32 week fetuses whose heart rates were generally slower and moved less
habituation
simple form of learning that involves a decrease in response to repeated or continued stimulation
As young as 30 week gestation shows habituation to both visual and auditory stimuli, indicating that their CNS is sufficiently developed for learning and short term memory to occur.
dishabituation
introduction to new stimulus rekindles interest following habituation to a repeated stimulus.
What has to happen in order to make a protien?
DNA has to be unwound from its histones. Called acetylation process
Biological drive to make sense of the world by 3 continuous processes (Paiget Theory)
1) Adaptation
2) Organization
3) Equilibration
Paiget argued that across all stages, learning unfolds through the processes of accomodation and assimilation. These processes lead to both short term learning as well as long term developmental stages.
Paiget’s theory 4 stages
1) Sensorimotor (0-2)
2) preoperational (2-7)
3) concrete operational (7-12)
4) formal operational (12+)
Sensorimotor stage example and thinking error
Infant cannot think about a cup of water unless they are experiencing it.
Object permanence >8 months
A not B error (infants will continue to look for hidden object, rather than new location it was hideen.)
Preoperational stage example and thinking error
Start to be able to represent experiences through language and symbolic thought
Ex: see a cup of water and know that the words “water” refer to the substance in the cup
Only tend to focus on one feature of an object; and error known as centration
Concrete operational example
Children can reason logically, but cannot think abstractly.
Ex: pour water from short glass into tall glass and understand the amount hasn’t changed.
Formal operational
Able to think abstractly and about hypothetical situations.
Can think more about moral, philosophical, ethical issues
Key components of information-processing theories
-Cognitive development is continuous
-Active child
-Thinking is a process that occurs over time
Cognitive development is continuous
basic learning and memory capabilities are present from birth and increase continuously over development
Problems with Paiget’s theory
stage model - children’s thinking not consistent
underestimated infants competence
underestimated influence of environment
Not all cultures reach formal operations stage
Information processing Theory
-Theories that focus on cognitive systems and processes
-Posits that childrens thinking is limited to;
hardware - memory + processing speed
software - availability of useful strategies and knowledge
-Theories focus on:
structure of cognitive systems
mental activities
how changes in thinking occur
Active Child
Children are active problem solvers, contributing to their own cognitive development
Thinking is a process that occurs over time (Information processing theories)
Simple behaviours like asking a question actually reflect a longer sequence of mental processes (e.g., remembering info relevant to question)
3 main cognitive capabilities that contribute to memory
1) changes in basic processes (associating, recognizing, recalling)
2) changes in strategies (rehearsal, elaboration, selective attention)
3) changes in content knowledge (improves encoding, provides guidelines for what is (an is not) possible/likely)
Sociocultural Theories - Vgotsky
1) Social interactions are important for learning
2) Role of culture in learning
3) Role of language in learning
4) Internalization of speech
5) Zone of proximal development
What is Vgotsky’s most famous contribution to cognitive development?
Zone of proximal development. The range of tasks a child can perform with assistance from others, but cannot yet perform independently.
-Direct Scaffolding
-Indirect Scaffolding
Direct Scaffolding
divide into smaller tasks, added structure, physical tools, feedback, questions about the task
Indirect scaffolding
creating an environment that supports learning
Dynamic systems theory
Focus on how change occurs over time in complex systems
Considers the complex interactions both within the child and their environment that might influence cognitive development
Posit development is non-linear (2 steps forward, 1 step back)
-the stepping reflex
Attractor states (Dynamic systems theory)
refer to each new motor skill; as its learnt it becomes deeper
4 major theories of cognitive development
Paiget - 4 stage model
Info processing - how we take in info influences our thinking
Sociocultural - emphasizes relationships. Includes language and culture
Dynamic Systems - interactions between factors that may impact dev.
Soft assembly (Dynamic systems theory)
motor skills assembled online; they are not hardwired, they are acquired through practice and through slow learning skills and skills learned in real time.
Minnesota study of twins
identified genetic contributions to “almost every behavioural trait so far investigated from reaction time to religiosity”
gene synthesis
A method in producing DNA
Development is a combined function of genetic and environmental factors
1) Parents genotyoe - child’s genotype
2) Child’s genotype - Chid’s phenotype
3) Child’s environment - Child’s phenotype
4) Child’s Phenotype - Child environment
5) Child’s environment - Child’s genotype
Parents genotyoe - child’s genotype
Involves transmission of genetic material from parent to offspring
- human heredity
-genetic diversity + individual differences
-sex determination
Child’s genotype - Chid’s phenotype
phenotype includes both physical and behavioural charactersitics
genes influence unobservable, intermediate aspects of the phenotype that impact behaviour - notably brain and nervous system
Intermediate phenotypes (endophenotypes) mediate the pathways between genes and behaviour
model of hereditary and environmental influences have 3 key elements
genotype
phenotype
environment
Child’s environment - Child’s phenotype
Because of continuous interaction of genotype and environment, a given genotype may develop differently in different environments.
Ex: a phenotype produced by genotype-environment interaction is PKU - a disorder related to a defective recessive gene on chromosome 12 - cannot metabolize phenylalanine (amino acid in red meat, aspartame)
Child’s Phenotype - Child environment
Active Child
Child’s environment - Child’s genotype
Although structure of genetic code remains “fixed” during one’s lifetime, the expression of genetic code is altered.
-specific gene does not lead to specific phenotype but that, instead, the genetic encoding of protiens alters the ways in which genes are expressed as phenotypes.
Behaviour Genetics
Quantitative genetics research designs (family study, twin studies)
Heritability
Molecular genetics research designs (DNA variation)
Environmental effects (growing up in the same family, experiences diverge, much harder to measure than genes)
Brain development
Collaboration between nature and nurture
Neuron; cell body ,dendrites, axon
Cortex; cerebral constitutes 80% of human brain, 4 main lobes, divided into 2 hemispheres.
