science warm-up 10/28/2012 write a paragraph that describes what physical abilities a professional...
TRANSCRIPT
Science Warm-up 10/28/2012
Write a paragraph that describes what physical abilities a professional soccer player should have. Also, include what physical features are not important for a soccer player to have.
Thank you for completing this individually and quietly.
Chapter 11: Complex Inheritance and Human
HeredityAaron Wood
By PresenterMedia.com
Overview
Section 1: Basic Patterns of Human Inheritance
Section 2: Complex Patterns of Inheritance
Section 3: Chromosomes and Human Heredity
Section 1: Basic Patterns of Human InheritanceOverview
Recessive genetic disordersDominant genetic disordersPedigreesAnalyzing pedigrees
Recessive Genetic Disorders
A recessive trait is expressed when the individual is homozygous recessive for the trait.
Ex) gg
Cystic Fibrosis
Affects the mucus-producing glands, digestive enzymes, and sweat glands.
Mucus is extremely thick, and extremely hard to get rid of.
1 in 3500 chances
Treatment is daily cleaningof the lungs, and medicine.
Albinism
Genes do not produce normal amounts of the pigment melanin.
1 in 17,000 occurrence
Galactosemia
Inability to break down galactose
Mental disabilities, enlarged liver, and kidney failure.
No cure 1 in 60,000 occurence
Tay-Sacs Disease
Absence of a substance that breaks down fatty substances.
Causes a buildup of fatty deposits in the brain, and mental delaying.
1 in 2,500 occurrence, mainly affects those with Jewish descent.
Dominant Genetic Disorders
Huntington’s disease
Achondroplaisia
Huntington’s Disease
A gene affecting neurological function is defective.
Decline of mental and neurological functions, and the ability to move deteriorates.
1 in 10,000 occurance
Achondroplasia
A gene that affects bone growth is abnormal.
Effects: short arms and legs, large head
Pedigrees
A pedigree is a diagram that traces the inheritance of a particular trait through several generations.
Compared to a family tree, but for a characteristic of disease.
Males are squares, females are circles. Normal is typically a blank circle, carriers are half-filled, and expressers are completely filled.
Analyzing Pedigrees
Inferring GenotypesKnowing physical traits can determine what genes an individual is most likely to
have.
Predicting DisordersRecord keeping helps
scientists use pedigree analysis to study inheritance patterns, determine phenotypes, and infer genotypes.
Section 2: Complex Patterns of Inheritance
Overview
Incomplete DominanceCodominanceMultiple AllelesEpistasisSex DeterminationSex-linked traits
Incomplete Dominance
This is when a heterozygous individual’s phenotype is an intermediate phenotype between the two homozygous phenotypes.
Codominance
This situation occurs when both alleles are expressed in the heterozygous condition
Ex) Sickle-cell disease
Sickle-cell disease
Changes in hemoglobin cause red blood cells to change to a sickle shape.
People who are heterozygous for the trait have both normal and sickle-shaped cells.
Sickle cell
Normal red blood cell
These sickle-cells are unable to carry as much oxygen as a normal cell. They also tend to block circulation in the hands and feet.
Why is there suchan overlap with sickle-cell andmalaria?
Individuals that are heterozygous for sickle-cell disease also have a higher resistance for malaria.
These individuals are more likely to survive and pass on the sickle-cell trait to offspring.
Multiple Alleles
Some forms of inheritance are determined by more than two alleles.
Ex) blood groups in humans (ABO)
Epistasis
Occurs when one allele hides the effects of another allele. This is the cause of coat color in Labrador retrievers.
No dark pigment present in fur Dark pigment present in fur
eebbeeB_ E_bb E_B_
Sex Determination
Sex chromosomes determine an individual’s gender.
For humans these are either the X chromosome and Y chromosome.
Sex-linked Traits
Genes located on the X chromosome
Color blindnessHemophilia
Color blindness
The trait for red-green color blindness is a recessive X-linked trait. This is very uncommon among females.
Hemophilia
A recessive sex-linked disorder, is characterized by delayed clotting of the blood.
Famous pedigree based on Queen Victoria of England (1819-1901)
Section 3: Complex Inheritance and Human Heredity
Overview
Environmental InfluencesKaryotypesTelomeresNondisjunction
Environmental Influences
The following things can impact the expression of certain characteristics
Environmental factorsDiet and exerciseSunlight and waterTemperature
Karyotype Studies
Micrograph in which the pairs of homologous chromosomes are arranged in decreasing size.
Karyotypes can be used to predict and test for genetic alterations.
Chromosomes are stained during metaphase.
Telomeres
Telomere caps consist of DNA associated with proteins
Serves as a protective function for the structure of a chromosome.
Nondisjunction
Cell division when sister chromatids fail to separate properly.
Causes disorders such as Down’s Syndrome.
Down’s Syndrome
Also known as trisomy 21.
Individuals receive an extra copy of the 21st chromosome.
Causes mental delaying and stunted growth.
Fetal Genetic Testing
There are different ways to test the genetic makeup of a fetus in the womb.
AmniocentesisChorionic villus samplingFetal blood sampling
Amniocentesis
Prenatal diagnosis of chromosomal abnormalities, and fetal infections.
Chorionic villus sampling
Removal of a small piece of the placenta tissue to determine chromosomal or genetic abonormalities.
Fetal blood sampling
Testing of a small amount of blood from the fetus to determine certain characteristics.