Basic Genetics
Phenotype – an organisms observable traits
Genotype – the traits that an organism can
pass on to its offspring through its genetic
material
Basic Genetics
• Genes - basic unit of heredity in a living organism
• Genes are located on chromosomes
– Threadlike structures in the nucleus of each cell
• Chromosomes occur in matched pairs
• Each species has a characteristic number of pairs
of chromosomes in each body cell
– Humans?
• The two genes (alleles) that control each trait are
situated at the same locus, one on each
chromosome of a particular pair.
Copyright © 2006 by Allyn and Bacon
Basic Genetics
Sex Chromosomes and Sex-linked Traits
 Sex chromosomes may not be matched pairs
 2 types of sex chromosomes – carry different genes
X
Y
 Female mammals have 2 X chromosomes
 Male mammals have X and Y chromosomes
Sex-linked traits – traits that are influenced by genes on the
sex chromosomes
 Mostly controlled by X chromosome
 Y chromosome – small, few genes
Basic Genetics
The Genetic Code and Gene Expression
 Several different kinds of genes
 Structural genes – contain information for the
synthesis of a protein
 Proteins – long chains of AA’s
 Control cellular activity
 All cells of the body contain exactly the same structural genes
 Operator genes – control structural genes (gene
expression)
 Function to determine whether each of its structural genes
initiates the synthesis of a protein and at what rate
* Major mechanism by which experience can interact
with genes to influence development
Mind and
Brain
Chapter 2
Structure and Functions of
Cells of the Nervous
System
Central Nervous System:
Brain
• The primary
function of the
brain is
behaviour.
– Sensing
– Perceiving
– Cognition
– Movement
Central Nervous System: Spinal Cord
• Primary relay
between the
external
environment and
the brain
• The same basic
components
– meninges
– CSF
– cells
Introduction
• The nervous system consists of 2 basic
divisions:
– The central nervous system – the brain and
spinal cord
– The peripheral nervous system – the part of
the nervous system outside the brain and
spinal cord, including the nerves attached to
the brain and spinal cord
Copyright © 2006 by Allyn and Bacon
Protecting the CNS
Meninges, Ventricles, and CSF
 CNS - encased in bone and
covered by three meninges
 Dura mater - tough outer
membrane
 Arachnoid membrane - weblike
 Pia mater - adheres to CNS
surface
 Cerebrospinal fluid (CSF)
 Fluid serves as a cushion
Protecting the Brain
 Physical protection
 Skull
 Meninges
 Cerebrospinal fluid (CSF)
 Chemical protection
 The blood-brain barrier – tightly-packed
cells of blood vessel walls prevent entry
of many molecules
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To understand how the nervous system controls
behavior, we must first understand its parts – the
cells that compose it
• Cells of the Nervous System
– Neurons
– Glial cells
• Communication Within a Neuron
• Communication Between Neurons
Introduction
• The brain is the organ that moves the muscles
– Movement, or behavior, is the primary function of the
nervous system
– Sensory neuron – a neuron that detects changes in
the external or internal environment and sends
information about these changes to the central
nervous system
– Motor neuron – a neuron located within the central
nervous system that controls the contraction of a
muscle or the secretion of a gland
– Interneuron – A neuron located entirely within the
central nervous system
Cells of the Nervous System
• Neurons
– Basic Structure
– Soma – cell body of a neuron which contains the
nucleus.
Figure 2.1
Cells of the Nervous System
• Neurons
– Basic Structure
– Dendrite – branched, treelike structure attached to
the soma; receives information from other neurons.
Figure 2.1
Cells of the Nervous System
• Neurons
– Basic Structure
– Axon – long, thin, cylindrical structure that conveys
information from the soma of a neuron to its
terminal buttons.
Figure 2.1
Cells of the Nervous System
• Neurons
– Basic Structure
– Terminal Button – bud at the end of a branch of
an axon; forms synapses with another neuron
Figure 2.1
Cells of the Nervous System
• Neurons
– Basic Structure
– Synapse – junction between the terminal button of an axon
and the membrane of another neuron.
– Neurotransmitter – a chemical that is released by a terminal
button
Figure 2.4
The Principal Parts: Together
Copyright © 2006 by Allyn and Bacon
Cells of the Nervous System
• Neurons
– Multipolar
– Unipolar
– Bipolar
• Glial cells
– Various types
– Provide a wide variety of supportive
functions
Cells of the Nervous System
– Types of Neurons
• Multipolar Neuron – neuron with one axon and many
dendrites attached to its soma; most common type in
CNS.
Figure 2.1
Cells of the Nervous System
Types of Neurons
• Bipolar Neuron – neuron with one
axon and one dendrite attached it its
soma.
– sensory systems (vision and
audition)
• Unipolar Neuron – neuron with one
axon attached to its soma; the axon
divides, with one branch receiving
sensory information and the other
sending the information into the
central nervous system.
– somatosensory system (touch, pain,
etc)
Figure 2.2
Copyright © 2006 by Allyn and Bacon