HUMAN GENETICS Review Mendel the father of genetics

HUMAN GENETICS

Review • Mendel – the father of genetics • Heredity – the passing on of traits • Homozygous Dominant – two copies of the dominant allele ( BB) • Homozygous Recessive – two copies of the recessive allele (bb) • Heterozygous – Two different alleles (Bb)

Determining Sex • Each of us has 44 Autosomes and two SEX CHROMOSOMES ( Total of 46 Chromosomes) • Sex chromosomes determine your SEX • XX ( female ) or XY ( male)

Sex Linked and X/Y linked Traits • Some genes are located on the X or Y chromosomes. • If there is error that occurs on either the X or Y chromosome then it is called SEX LINKED. • X- Linked means that it is carried on the X Chromosome • Y – Linked means that it is carried on the Y chromosome

What is Linkage? • Linkage occurs when two genes occur close together on a chromosome • The are always passed on together. • The Location or LOCI can be found indicated on a Chromosome map.

What are polygenetic traits? Polygenic traits are controlled by two or more genes (a single inherited phenotypic trait that is controlled by two or more different genes- think back to tossing the pennies 6 times in our baby lab to determine what skin color your baby would have) Examples include: • Skin color • Eye color • Height • Foot size Watch the video: https: //www. youtube. com/watch? v=7 Q 29 SE 8 z. Yyg

What are multiple allele traits? • This happens when there are 3 or more alleles of the same gene for a single trait. • Ex Blood Types A, B, O Groups. They are all variations of the gene for blood type indicated by an I • Types A and B are CODOMINANT. • Type O is RECESSIVE TO A and B.

Mutations Review

Mutations- In Genes 1. Point Mutation- when there is change in one nitrogenous base. -Substitutions – when one base is changed but everything else is unaffected. -Insertions -Deletions 2. Frameshift – when one or more base (s)s ( nucleotide) are substituted, added or deleted that changes how the codons are read.

Example of Gene a Mutation Sickle cell anemia – one A is substituted by a T and causes the RBC to become sickle shaped. Affects people of African descent. Provides some protection from malaria.

Chromosomal Mutations 1. Deletions – when part of a chromosome is deleted. 2. Insertions- when part of a chromosome is inserted. 3. Inversion – when a piece of a chromosome is flipped. 4. Translocation – when a piece of a chromosome breaks off and attaches somewhere else. 5. Nondisjunction – when homologous pairs fail to separate during meiosis.

Examples of Chromosomal Mutations 1. Down’s Syndrome – 3 copies of chromosome 21 ( TRISOMY) 2. Kleinfelters syndrome – XXY (TRISOMY) 3. Turner’s syndrome- XO ( MONOSOMY)

Why do mutations occur? • • Chemical mutagens Viruses Radiation High Temperature Remember that some cancers can be caused by mutations that lead to uncontrolled cell division.

Other Genetic Disorders • • • Huntington’s Dwarfism Polydactyl Cataracts Albinism PKU ( Phenylketonuria) • • • Tay Sachs Cystic Fibrosis Muscular Dystrophy Hemophilia Color Blindness (Blue = Sex-linked )

Cystic fibrosis • Autosomal recessive disorder that affects 1/2000 Caucasians. • Cystic fibrosis is an inherited disorder that causes severe damage to the lungs, digestive system and other organs in the body. • A defective gene causes the secretions to become sticky and thick. Instead of acting as a lubricant, the secretions plug up tubes, ducts and passageways, especially in the lungs and pancreas.

Tay-Sachs • Autosomal recessive disorder • This defective gene causes the body to not make a protein called hexosaminidase A. • Without this protein, chemicals called gangliosides build up in nerve cells in the brain, destroying brain cells.

Phenylketonuria (PKU) • Autosomal recessive disorder • A disorder that increases the levels of a substance called phenylalanine in the blood. Phenylalanine is a building block of proteins (an amino acid) that is obtained through the diet. It is found in all proteins and in some artificial sweeteners. • A buildup can result in the following symptoms: musty odor, skin rashes, neurological issues (seizures), delayed development, and behavioral and social issues.

Albinism • Autosomal recessive disorder • Individuals have little or no pigment in eyes, skin, or hair. • Cells don’t produce the normal amount of melanin.

Sickle- Cell Anemia • Autosomal recessive disorder that affects 1/500 African-Americans and 1/12 African- Americans are carriers. • Individuals with this disorder have atypical hemoglobin molecules called hemoglobin S, which can distort red blood cells into a sickle, or crescent, shape. • Signs and symptoms of sickle cell disease usually begin in early childhood. Characteristic features of this disorder include shortness of breath, pain due to blood clots, swelling of hands and feet, frequent infections, delayed growth, and vision problems.

Huntington’s Disorder • Autosomal dominant disorder that affects 1/10, 000 people. • An inherited disorder in which nerve cells in the brain break down over time. • Eventually results in uncontrolled movements, emotional problems, and loss of cognitive abilities.

Blood Types • Autosomal inheritance that involves multiple alleles. • Remember A and B are co-dominant. • Blood type is determined by the antigens on the surface of the red blood cell. • Can have type A, B, AB, and O.

Hair Color, Eye Color, Skin Color, & Height • Polygenic inheritance

Color-Blindness • Recessive, sex-linked inheritance. • Condition characterized by the inability to clearly distinguish different colors of the spectrum.

• Recessive, sex-linked inheritance. Hemophilia • A rare disorder in which your blood doesn't clot normally because it lacks sufficient blood-clotting proteins (clotting factors). • If you have hemophilia, you may bleed for a longer time after an injury than you would if your blood clotted normally

Muscular Dystrophy • Recessive, sex-linked disorder. • Disorder characterized by progressive weakness and degeneration of the skeletal or voluntary muscles which control movement.

Down’s Syndrome • Inherited through non-disjunction in sex chromosomes. • Disorder in which the individual has distinct facial features, upward slanted eyes, poor muscle tone, short fingers and toes, small hands and feet, short height, and intellectual disabilities.

Turner’s Syndrome • Inherited through non-disjunction in sex chromosomes. • Disorder that affects females only. • These females have a short stature, delayed puberty, infertility, heart defects, and learning disabilities.

Klinefelter’s Syndrome • Inherited through non-disjunction in sex chromosomes. • Males with this disorder have an extra X chromosome. • These males experience reduced muscle mass, reduced facial and body hair, enlarged breast tissue, taller than average stature, weak bones, and smaller genitals.

Pattern Baldness • Inherited through a sex-influenced trait • Individuals with baldness have a receding hairline and hair thinning on the crown of their head.

How can we detect genetic Disorders? Genetic Screening Examine the family history of the individual. - Pedigree ( a chart showing inheritance of traits or disorders over generations ) Karotyping ( a picture of your choromosomes)

What if a problem is suspected? Genetic counseling – advise couples trying to have babies of the risks that may affect their offspring. Genetic Testing: • Amniocentesis – fluid is drawn form amniotic sac to detect disorders • Fetoscopy –surgery or samples taken from fetus • Chorion Villi sampling- used for karoytyping • Ultrasonography

Cancer and Vitamin D • Vitamin D produced by the body as a response to sun exposure; it can also be consumed in food or supplements. • Vitamin D helps your support your immune system, helps prevent and fight cancer, and in angiogenesis or the formation of new blood vessels. • To obtain vitamin D you need to be out in the sun however if you are out in the sun to much there is the risk of altering DNA in the skin and causing skin cancer. Need a balance.

• Your pancreas makes a hormone called insulin. It's what lets your cells turn glucose from the food you eat into energy. People with type 2 diabetes make insulin, but their cells don't use it as well as they should. Doctors call this insulin resistance. • Genetics, obesity, and diet can all be a factor in causing this type of diabetes.

Type 2 Symptoms • Symptoms include increased thirst, frequent urination, hunger, fatigue, and blurred vision. In some cases, there may be no symptoms.

• Diabetes can cause serious health problems, such as heart disease, stroke, and eye and foot problems. • Prediabetics also can cause health problems. The good news is that type 2 diabetes can be delayed or even prevented. • The longer you have diabetes, the more likely you are to develop health problems, so delaying diabetes by even a few years will benefit your health. • You can help prevent or delay type 2 diabetes by losing a modest amount of weight by following a reduced-calorie eating plan and being physically active most days of the week.

Type II Diabetes Prevention • Lose weight and keep it off. You may be able to prevent or delay diabetes by losing 5 to 7 percent of your starting weight. 1 For instance, if you weigh 200 pounds, your goal would be to lose about 10 to 14 pounds. • Move more. Get at least 30 minutes of physical activity 5 days a week. If you have not been active, talk with your health care professional about which activities are best. Start slowly to build up to your goal. • Eat healthy foods most of the time. Eat smaller portions to reduce the amount of calories you eat each day and help you lose weight. Choosing foods with less fat is another way to reduce calories. Drink water instead of sweetened beverages.

Environmental Influences • An environmental influence is any external factor such as air, water, minerals, and other organisms surrounding and affecting a given organism at any time.

Background ( Review) • A gene is expressed when a protein is made. • Proteins are composed of amino acids • A zygote is formed when an egg is fertilized by a sperm. • A zygote divides and differentiates into many different types of cells such as blood, nerve, and muscle cells via cell differentiation. – Cell differentiation is when some genes are selectively turned on or off in a cell.

What Influences Gene Expression? • Gender: – Pattern Baldness- expressed mostly in males due to higher levels of testosterone. – Lactation – Breast Cancer

Other Environmental Influences • Pollutants • Day Light Exposure Time • Color of Light • Temperature