Genetic Foundations
- We carry a genetic code we get from our parents
- This code is in all our cells
- The code is how we pass on our characteristics to our kids
Genetic Building Blocks
- DNA
- Genes
- Chromosomes
DNA
Deoxyribonucleic Acid is a complex molecule, shaped like a double helix, that contains genetic information.
Genes
The units of hereditary information- short segments composed of DNA- that act as a blueprint for cells to reproduce themselves and manufacture the proteins that maintain life.
Chromosome
Threadlike structures that come in 23 pairs, one member of each pair coming from each parent.
Chromosomes contain the genetic material DNA.
Genetic Principles
- Dominant-Recessive genes principle
- Sex-Linked genes
- Polygenically inherited characteristics
Dominant-Recessive Genes Principle
- If one gene of a pair is dominant and one is recessive, the dominant gene exerts its effect, overriding the potential influence of the other, recessive gene.
- A recessive gene exerts its influence only if the two genes of a pair are both recessive.
Sex-Linked Genes
Two of the 46 chromosomes human beings normally carry are sex chromosomes. Ordinarily females have two X chromosomes and males have an X and a Y.
Polygenic Inheritance
- The genetic principle that many genes can interact to produce a particular characteristic.
- There are more than 60,000 genes, imagine the possible combinations!
Genotype
An individual's genetic heritage, the actual genetic material
Phenotype
The visible and measurable characteristics of a person's Genotype.
- Physical traits: height, weight, eye color
- Psychological characteristics: intelligence, creativity, personality
Genotypes & Phenotypes
For each Genotype, a range of Phenotypes can be expressed.
Behavior Genetics
- This is the study of the degree and nature of behavior's hereditary basis.
- Believes that behavior is due to a combination of heredity and environment.
- Behavior genetics often uses twins or adoption situations to study the influence of heredity on be
Twin Studies
- The behavioral similarity of identical twins is compared with the behavioral similarity of fraternal twins
- Identical twins (monozygotic twins) develop from a single fertilized egg that splits into two genetically identical replicas, each of which beco
Issues with Twin Studies
- By comparing groups of identical and fraternal twins, behavior geneticists capitalize on the basic knowledge that identical twins are more similar genetically than are fraternal twins.
- However, adults might stress the similarities of identical twins m
Adoption Studies
- Investigators seek to discover whether, in behavior and psychological characteristics, adopted children are more like their adoptive parents, who provided a home environment, or more like their biological parents, who contributed their heredity.
- Anoth
Molecular Genetics
Branch of science that determines the genes that determine a person's susceptibility to diseases and other aspects of health and well being.
Genome
- The term used to describe the complete set of instructions for making an organism
- Contains the master blueprint for all cellular structures and activities for the life span of the organism
- The human genome consists of tightly coiled threads of DNA
The Human Genome Project
- Began in the 1970's
- Is the process of mapping the human genome
- Has located the genes for Huntington disease, some forms of cancer, and many others
- May possibly be used to transplant healthy copies of missing/defective genes into affected cells
- M
Chromosomes Abnormalities
- Down Syndrome
- Klinefelter Syndrome
- Fragile X Syndrome
- Turner Syndrome
- XYY Syndrome
Gene-Linked Abnormalities
- Phenylketonuria
- Sickle-Cell Anemia
Down Syndrome
Caused by the presence of an extra chromosome
Characterized by:
- Round face
- Flattened Skull
- Extra fold of skin over the eyelids
- protruding tongue
- short limbs
- retardation of motor and mental abilities
- Woman younger than 18 and older than (40-4
Klinefelter Syndrome
Sex-Linked chromosome abnormality
Males have an extra X chromosome, makng them XXY instead of XY
Characterized by:
- Undeveloped testes
- enlarged breasts
- become quite tall
Fragile X Syndrome
Sex-Linked chromosome abnormality
The X chromosome becomes constricted and often breaks
Characterized by:
- mental deficiency (varied in form from mental retardation to short attention span)
Occurs frequently in males
(Cry-du-Chat) Syndrome
Turner Syndrome
Sex-Linked chromosome abnormality
Females are missing an X chromosome, making them XO instead of XX
Characterized by:
- Shortness of stature
- webbed neck
- possible mental retardation
- possible sexual underdevelopment
XYY Syndrome
Sex- Chromosome linked abnormality
The male has an extra Y chromosome
Early belief surrounding the syndrome was that the extra Y chromosome contributed to male aggression and violence
Researchers have since found that XYY males are no more likely to commi
Phenylketonuria
Gene-Linked abnormality
The individual cannot properly metabolize an amino acid (phenylalanine)
Currently easily detected
Treated by diet to prevent an excess accumulation of phenylalanine.
If left untreated it can result in mental retardation and hyperac
Sickle-Cell Anemia
Gene-Linked abnormality
Occurs most often in African Americans
Affects the shape of red blood cells, hindering their ability to carry oxygen to the body's cells
Results in anemia and early death of the individual
Other Genetic Abnormalities
- Cystic Fibrosis
- Diabetes
- Hemophilia
- Huntington Disease
- Spina Bifida
- Tay-Sachs Disease
Reproduction Challenges & Choices
- Prenatal Diagnostic Tests
- Infertility
- Adoption
Prenatal Diagnostics Tests
- Amniocentesis
- Ultrasound Sonography
- Chorionic Villi Sampling
- Maternal Blood Test
Amniocentesis
- A prenatal medical procedure in which a sample of amniotic fluid is withdrawn by syringe and tested to discover if the fetus is suffering from any chromosomal or metabolic disorders
- Performed between the 12th and 16th weeks of pregnancy
- There exists
Ultrasound Sonography
- A prenatal medical procedure in which high frequency sound waves are directed into the pregnant woman's abdomen
- Echo from the sounds is transformed into a visual representation of the fetus's inner structures
- Able to detect such disorders as microen
Chorionic Villi Sampling
- A prenatal medical procedure in which a small sample of the placenta is removed
- Performed between the 8th and 11th weeks of pregnancy
- Provides information about the presence of birth defects
- Has a slightly higher risk of miscarriage than amniocent
Maternal Blood Test
- Called the alpha- fetoprotein (AFP) test
- A prenatal diagnostic techique used to assess blood alphaprotein level, which is associated with neural-tube defects
- Administered between the 14th and 20th weeks of pregnancy
Infertility
Infertility is the inability to conceive a child after 12 months of regular intercourse
Causes of Infertility (Women)
- Ovulation problems
- Antisperm secretions
- Blocked Fallopian tubes
- Endometriosis
Causes of Infertility (Men)
- Low sperm count
- Immobile sperm
- Antibodies against sperm
Infertility techniques
- (IVF) In Vitro Fertilization
- (GIFT) Gamete IntraFallopian Transfer
- (ZIFT) Zygote IntraFallopian Transfer
- (ICSI) IntraCytoplasmic Sperm Injection
- (IUI) IntraUterine Insemenation
(IVF) In Vitro Fertilization
Egg and sperm are combined in a laboratory dish and resulting fertilized embryo is transferred into the woman's uterus. (Success rate slightly less than 25%)
(GIFT) Gamete IntraFallopian Transfer
A doctor inserts eggs and sperm directly into a woman's Fallopian tube. (Success almost 30%)
(ZIFT) Zygote IntraFallopian Transfer
Eggs are fertilized in the laboratory then any resulting zygotes are transferred to a Fallopian Tube. (25% chance of success)
(ICSI) IntraCytoplasmic Sperm Injection
A single sperm is injected by pipette into an egg and the zygote is returned to the uterus. (25% chance of success)
(IUI) IntraUterine Insemenation
Frozen sperm, of the husband or donor, is placed directly into the uterus (10% chance of success)