PSYC 3850 Chapter Notes - Chapter 4: Genetic Counseling, Nuclear Membrane, Hydrogen Bond

31 views10 pages
PSYC 3850
CHAPTER 4
GENETIC AND CHROMOSOMAL FACTORS
There are at least three reasons why understanding genetic and chromosomal
disorders are important:
- Implications for prevention
- Treatment
- Genetic Counseling
The Role of Genes and Chromosomes In Heredity
At the time of conception, when the sperm from a male unites with the ovum from a
female a single cell known as zygote results creating the blueprint of the person. It
eventually duplicates itself over and over until it becomes a living organism with its
unique characteristics.
Cells and Their Structure
There are two types of cells:
- Somatic (body)
- Germ (sex)
Each of these is involved in different types of cell divisions. The stricture of all cells
is the same (page 95) as they include a cell membrane (surrounds the cell matter or
cytoplasm) In the cytoplasm there is the nucleus surrounded by the nuclear
membrane. The nucleus is viral to hereditary as it includes the chromosomes on
which the genes are located. Genes are considered the basic/smallest unit when it
comes to hereditary. The genetic blueprint is known as a genotype.
Composition of the Chromosomes and Genes
Chromosomes are made up of strands of DNA. Watson and Crick suggested that DNA
looked like a double spiral (helix) similar to a twisting ladder that consists of several
chemicals including phosphates, sugars, and nitrogen bases. It has four bases:
- Adenine (A)
- Thymine (T)
- Guanine (G)
- Cytosine (C)
The function of DNA is the unique way in which these bases are joined together to
form base pairs VIA a hydrogen bond. The rungs would have four possible
combinations: AT, TA, GC or CG. There are estimates that we house almost 3 billion
base pairs. They dictate inherited characteristics through the process of
synthesizing specific proteins that are needed by the body at various stages of
development occurring through biochemical, transmission VIA ribonucleic acid.
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 10 pages and 3 million more documents.

Already have an account? Log in
Human Genome Project: designed to identify the exact chromosomal location of all
human genes and determine their function related to health and disease. There was
also a goal to complete the sequence of the 3 billion bases.
Number and Types of Chromosomes
We have 46 chromosomes that are paired together. 22 pairs are known as
autosomes. The 23rd pair is known as the sex chromosomes determining the sex of
the offspring. Females have XX while males have XY. Chromosome pairs have a
numerical designation (1-23) and are grouped with a letter designation (A-G).
Karotype: shows the magnified chromosomes placed in pairs and they are placed in
regards to their length. It may help indicate an obvious abnormality.
Cell Division
Meiosis: the cell division occurs within the sex cells. It is known as reductive due to
the fact that the 46 chromosomes are halved (haploid state). This results in the
sperm and ova each containing 23 chromosomes.
Mitosis: refers to somatic cell division where the chromosomes in the nucleus
duplicate themselves before dividing. After the genetic code has been set through
conception, each of the 46 chromosomes of the newly formed zygote initially split
by having the pairs break. Then, each separate strand will act as a template for the
development of the new strands due to the fact that each base needs to bond with
the analogous base. When the cell (parent cell) divides, the two new cells known as
daughter cells will contain 46 chromosomes.
Autosomal Genetic Disorders
Genes that produce different characteristics are known as alleles; a child with
inherit one from each biological parent. They can either have a homozygous pairing
(GG) or heterozygous pairing (Gg). There are two accepted explanations:
- IGOD: suggests that the precense of a single gene will result in the disorder
- OTL: suggests that there are multiple genes in combination that are the cause
of the disorder
- Multifactorial Transmission: combination of genetic and environmental
factors.
Single gene disorders can be either dominant or recessive.
Autosomal Dominant Disorders
If either of the parents passes on the allele for a given disorder, the child will have
the disorder. In rare instances, a child will not inherit the dominant disorder. This is
known as nonpenetrance. A punnett square demonstrates the various genetic
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 10 pages and 3 million more documents.

Already have an account? Log in
combinations that result from a mother and father with the known allele pairs.
However it is only a theoretical possibility.
Tuberous Sclerosis (TS)
Caused by a nonworking gene that is located on either the 9th or 16th chromosome.
These genes ordinarily act to suppress the development of tumors in the body. The
condition is characterized by tumors that can affect a number of organs including
the brain. The tumors are shaped like tubers (potatoes) and calcify (become
sclerotic) with age. Another common characteristic is the presence of skin lesions
that can take on several forms: red, vascular lumps on the face. Most causes are due
to new mutations.
Neurofibromatosis (NF)
NF, the growth of tumors can occur in either the PNS or the CNS.
- NF1: results in multiple tumors (neurofibromas) or “café au lait” spot lumps
on the skin above the peripheral nerve and the nodules on the eyes. It can
also result in macrocephaly along with bone malformation. The hallmarks
are: cognitive implications, learning disabilities along with emotional and
behavioral difficulties
- NF2: results in tumors that can lead to hearing loss.
A parent with NF1 or NF2 will always have a child with the same type, but
the severity can be different.
Autosomal Recessive Disorders
If it is recessive in nature, both parents must pass that particular allele to the child
for them to inherit the disorder. Many of these disorders leading to CID’s are
metabolic disorders due to having enzyme deficiencies resulting in the inability to
break down certain substances in the body and excessive accumulation can lead to
toxic side effects. These conditions are often known as “inborn errors of
metabolism”. They are also linked to ethnic background.
Galactosemia
It is caused by the lack or insignificant reduction of the enzyme galactose which
breaks down the carbohydrate sugar. These sugars are converted to glucose for the
body to use as energy but the lack of enzyme stops this process from happening. It
has serious consequences such as: brain damage resulting in a CID, cataracts, and
the failure of organs including liver and kidneys. It can be identified within the first
week of life using a blood test and treatment can be initiated immediately. Even with
treatment there is some evidence that they may still have lower IQ’s and speech
difficulties.
Hurler Syndrome
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 10 pages and 3 million more documents.

Already have an account? Log in

Document Summary

There are at least three reasons why understanding genetic and chromosomal disorders are important: The role of genes and chromosomes in heredity. At the time of conception, when the sperm from a male unites with the ovum from a female a single cell known as zygote results creating the blueprint of the person. It eventually duplicates itself over and over until it becomes a living organism with its unique characteristics. Each of these is involved in different types of cell divisions. The stricture of all cells is the same (page 95) as they include a cell membrane (surrounds the cell matter or cytoplasm) in the cytoplasm there is the nucleus surrounded by the nuclear membrane. The nucleus is viral to hereditary as it includes the chromosomes on which the genes are located. Genes are considered the basic/smallest unit when it comes to hereditary. The genetic blueprint is known as a genotype. Chromosomes are made up of strands of dna.

Get access

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