INFLUENCE OF HEREDITY

Heredity: the passing on of certain

characteristics from earlier generations.

Can be……Eye color, hair color, height, body build, blood type, intelligence, gender, and many other characteristics

Explains why brothers and sisters often resemble each other.

Also explains why brothers and sisters often look very different.

Genes: biochemical messenger that

determines inherited characteristics.

The features and capacities we inherit are determined by genes given to us at the moment of conception.

Characteristics can be physical and mental

Come from both parents and combine to make different combinations.

Some genes are dominant and some are recessive.

Chromosome: a threadlike strand of DNA in

the cell nucleus that carries the genes

Sex chromosomes are identified by the symbols X and Y, and determine the gender of the child.XX = Female

XY = Male

Female will pass on an X chromosome, while the male can pass on either. Gender is determined by the father!

Genetics: scientific study of inherited

traits.

Each person begins life with his/her own set of blueprints or specifications.

Individuals normally inherit 23 pairs of chromosomes.

When the sex cell of a female, containing 23 chromosomes, combines with the sex cell of a male, containing 23 chromosomes, the result is a cell containing 46 paired chromosomes.

One chromosome in each pair comes from the mother and one from the father.

Each chromosome is made up of thousands of genes.

DOMINATE Gene: More powerful - trait seen in person

RECESSIVE Gene: Weaker and hides in the background. Trait can only determine when two of them are present - may show up in future generations.

CARRIER: Has a recessive gene that is not visible

SEX-LINKED: Mother passes the recessive X to son

Color-blind male receives the trait from his mother.

The mother is usually not color-blind herself.

B = BROWN eyes (dominate) b = BLUE eyes (recessive)

BB = BROWN eyes

bb = BLUE eyes

Bb = BROWN eyes but carry the recessive BLUE eye gene

MULTIPLE BIRTHS

MONOZYGOTE: Identical Twins 1 Egg + 1 Sperm

Fertilized ovum splits into 2 identical cells - Always the same gender

DIZYGOTE: Fraternal Twins 2 Eggs + different Sperm

Will look different - May be different or the same gender

MULTIPLE BIRTHS: More than 2

May be identical, fraternal or both - May be different or the same gender

CONJOINED (Siamese) TWINS: Ovum splits apart, but the separation is not completed. Babies are joined at some part of their bodies.

ZYGOTE: the cell that is formed when a sperm fertilizes an egg (ovum)

FACTORS that may contribute to Multiple Births….

1) History in the family

2) Increased hormones naturally More than one egg released

3) Fertility DrugsMore than one egg released

4) Age: 30’s and 40’s

Diseases or Disabilities

Sometimes, as the chromosomes come together and the genes matchup they do not pair properly and certain diseases or disabilities may be passed on to the child.

Syndrome: When a group of signs and symptoms occur

together and characterize a particular problem.

Congenital Malformation: A condition that is

present at birth.

Multi-factorial Defects: Interaction of genes , gene

combinations or with environmental factors.

Chromosomal Error: The fertilized egg cell that

contains chromosomes in an abnormal number, structure or arrangement.

Diseases or Disabilities

Genetic Counseling Genetic counselors help people understand the way

hereditary diseases and disabilities are passed on. They help parents weigh options and risks.Research the problem

Tests are given (amniocentesis)

Doctors study the cell to determine if faulty chromosomes have been passed onto the fetus.

Even though there are many possibilities that a child may be born with a hereditary disease or disability, the majority of children come into this world as healthy, happy babies. It is a miraculous happening!

Genetic Testing

Ultrasound: uses sound waves and converts them into a image of the fetus in the womb

Amniocentesis: sample of amniotic fluid to detect birth defects.

Chronic Villus Sampling: tissue sample is taken from the amniotic sac.

CASE STUDY:There are many factors that influence the development of a child.

Heredity Influences: Genetic characteristics

Environmental Influences: Learned characteristics

Sammy has brown eyes and is five years old. She attends a neighborhood preschool everyday. Her teachers have fallen in love with her witty personality and honey-colored hair. She is very intelligent and does well with the task assigned her. Sammy’s parents are divorced and she misses her father very much. Sammy has Juvenile Arthritis and must see a doctor often. At her last doctor’s visit, the doctor reminded Sammy’s mom that diabetes has run in her family for several generations and that Sammy should be watched closely for any early symptoms of diabetes. Sammy’s growth chart shows that she will probably be small for her age.

List the various influences in the correct categories:

Heredity vs. Environmental

Assignment

Complete the assignment in your packet:

Heredity vs. Environment

Mark an “H” for heredity

Mark an “E” for environment

Mark a “B” for both