PSYC3850 Chapter 4: Chapter 4

57 views16 pages
Chapter 4
Genetic and Chromosomal Factors
Key Points
- The role of genes and chromosomes in heredity
oChromosomes are made up of strands of DNA
oThere are 22 pairs of autosomes and 1 pair of sex chromosomes
oGenes are located on the chromosomes and dictate inherited characteristics
- Autosomal genetic disorders
oDisorders can be dominant (tuberous sclerosis, neurofibromatosis) or recessive (PKU,
Tay Sachs)
- Sex-linked genetic disorders
oFragile X is the most common, genetically inherited form of cognitive/intellectual
disability
oOther sex-linked disorders include Lesch-Nyhan and Rett syndrome
- Disorders related to the number of chromosomes
oCan result from nondisjunction, translocation, and mosaicism
oMost common is Down syndrome
- Disorders related to the structure of chromosomes
oMost common cause is a deletion of part of a chromosome
oPrader-Willi syndrome is caused by a deletion of the long arm of chromosome 15
- Disorders with multiple or unknown causes
oConditions with multiple causes include hydrocephalus and microcephalus
oSturge-Weber is a disorder with an unknown cause
- CIDs are primarily the result of environmental or unknown causes
oHowever, there are a number of genetic and chromosomal causes
- 3 reasons understanding genetic and chromosomal disorders is important
oPrevention
find more resources at oneclass.com
find more resources at oneclass.com
Unlock document

This preview shows pages 1-3 of the document.
Unlock all 16 pages and 3 million more documents.

Already have an account? Log in
Through techniques such as gene therapy, the possibility of preventing
disorders exists
oTreatment
With early screening and detection is possible to treat some disorders to avoid
serious consequences
oGenetic counseling
Improved diagnostic procedures have given parents increased knowledge about
the nature of their unborn baby
Genetic counselors can provide information and support to those parents
Can also test parents to give a better idea of the probability of having a child
with the disorder
The role of genes and chromosomes in heredity
- At conception, a male sperm unites with a female ovum, forming a single cell called a zygote
oAt that point the genetic blueprint of the individual is determined
oThe zygote duplicates over and over to become a living organism, complete with its
unique characteristics
Genes and chromosomes play an important role in this development
- Cells and their structure
oThere are 2 types of cells
Somatic cells (body cells) and germ cells (sex cells)
oThe structure of all cells is the same
Cell membrane
Surrounds the cell matter or cytoplasm
In the cytoplasm is the nucleus
Is surrounded by the nuclear membrane
Is vital to heredity as it includes the chromosomes
oOn which the genes are located
The smallest, most basic unit of heredity
Provides a blueprint for the characteristics and
functions of the human body
find more resources at oneclass.com
find more resources at oneclass.com
Unlock document

This preview shows pages 1-3 of the document.
Unlock all 16 pages and 3 million more documents.

Already have an account? Log in
Genes for specific functions have specific
locations on the chromosomes and are the
chemical determinants of heredity
This genetic blueprint is called a genotype
oChromosomes contain all inherited material that is passed
generation to generation
- Composition of chromosomes and genes
oChromosomes are made up of deoxyribonucleic acid (DNA)
DNA
A helix composed of several chemicals
oThe strands are phosphates and sugars
oNitrogenous bases form the rungs
There are 4 bases:
Adenine (A), thymine (T), guanine (G), and
cytosine (C)
The bases are joined together to form base pairs via
hydrogen bonds
A-T, G-C
One on each side of the rung
Human chromosomes house ~3 billion base pairs
oGenes, located on the chromosomes, contain thousands of base pairs
They dictate inherited characteristics through the process of synthesizing
specific proteins needed by the body at different stages of development
Occurs through biochemical transmission via ribonucleic acid (produced
by DNA)
oAttempts have been made to determine the specific location of various genes (genetic
mapping) and the sequencing of base pairs
Human Genome Project was involved in mapping over 30,000 genes and
sequencing over 3 billion chemical combinations that make up human DNA
- Number and types of chromosomes
oHumans have 46 chromosomes that are paired together
find more resources at oneclass.com
find more resources at oneclass.com
Unlock document

This preview shows pages 1-3 of the document.
Unlock all 16 pages and 3 million more documents.

Already have an account? Log in

Get access

Grade+
$10 USD/m
Billed $120 USD annually
Homework Help
Class Notes
Textbook Notes
40 Verified Answers
Study Guides
1 Booster Class
Class+
$8 USD/m
Billed $96 USD annually
Homework Help
Class Notes
Textbook Notes
30 Verified Answers
Study Guides
1 Booster Class