UNIT 9 THE HUMAN GENOME I HUMAN GENETICS

UNIT 9 – THE HUMAN GENOME

I. HUMAN GENETICS (pp. 311 -313) A. Human Somatic Cells body diploid 2 n l ____ cells are ______ or __. 46 l Each cell contains ___ chromosomes, 23 or ___ pairs of chromosomes. 22 – Of the pairs, ___ are ______, homologous contain the same genes in the same order, and are called ______. autosomes

A. Human Somatic Cells l The 23 rd pair of chromosomes are the ____ chromosomes. sex – – Female =___ XX Male= ___. XY

B. Human Gametes are _______, or __, and haploid 23 contain ___ chromosomes. egg l Female gametes are _____ cells made ovaries in the ______ in the process of _____. meiosis sperm l Male gametes are ______cells made in the _____ in the process of testes meiosis _____. l

B. Human Gametes l l Egg cell can only contain an __ chromosome X Sperm cell produced has a ___% chance of 50 Y containing a ___ and a ___% chance of 50 containing an __. X – The _____ determines the sex of the offspring. male

C. Analyzing Human Chromosome Numbers Nondisjunction Abnormal numbers of gametes chromosomes in ______ result number disorders in genetic disorders called ______. nondisjunction “not coming apart” l ______, which means _______. 1.

C. Analyzing Human Chromosome Numbers A chromosome pair fails to separate anaphase correctly in ____ so the gametes produced have an abnormal ___________. number of chromosomes l Number disorders are not inherited; therefore, they cannot be predicted Punnett squares with ________. l

C. Analyzing Human Chromosome Numbers 2. l l Karyotypes – A karyotype is a photograph of ________. chromosome pairs mitosis Cells are stopped during _____ and are stained, photographed, and the photograph is enlarged.

C. Analyzing Human Chromosome Numbers The chromosomes are cut out and homologous arranged in ______ pairs in size order, with the ____ chromosomes sex making up the 23 rd pair. number l Used to detect _____ disorders gender and to determine the ____ of an unborn child. l

C. Analyzing Human Chromosome Numbers They do not detect abnormal _______; genes therefore, a normal karyotype does not normal guarantee a ______ child!

II. HUMAN GENETIC DISORDERS – NUMBER DISORDERS (pp. 313 -314) A. Autosomal Number Disorders l Most are _____. lethal l The only autosomal number disorder that allows survival into adulthood is Down syndrome __________.

Is there a problem with this karotype

A. Autosomal Number Disorders Down syndrome trisomy 21 l known as _____ because there are ___ chromosomes at the 3 21 st 2 ____ position, instead of ___. l Individuals have characteristic facial features; growth, behavior, and mental development are all affected

Autosomal Number Disorders Down syndrome There is also a higher risk of congenital _____ heart defects. l The incidence of babies with Down syndrome is much o older higher in ______ l mothers. l

Is there a problem with this karyotype?

B. Sex Chromosome Number Disorders 1. Turner Syndrome 45 XO l Called ______ l l because individuals lack _________. 2 nd sex chromosome female _______, typically ______ in stature, short underdeveloped sexually, sterile ______, with a normal life expectancy.

Does this individual have a number disorder?

B. Sex Chromosome Number Disorders 2. Klinefelter Syndrome 47 XXY l Called ____. l l Symptoms do not appear until ____ at which time puberty affected _____ show males poor sexual development and infertility. testosterone Treated with _____. Normal life expectancy.

B. Pedigrees (pp. 299 -301) l A pedigree is a diagram that follows the trait inheritance of a single _____ through several generations ______ of a family. – – l squares Males are represented by ____ circles Females, by _______. Individuals with the trait are represented shaded with ____ figures.

B. Pedigrees Individuals shown with unshaded figures _________. do not show the trait parents children l Vertical lines connect _______ and _______. spouses l Horizontal lines connect _____ or siblings _____. birth order l Children are placed in _____, from left to right _____. l

l Complete pedigrees in note packet

IV. INHERITED HUMAN GENETIC DISORDERS Gene Mutations a change in the DNA sequence of the gene _______________. A. l Causes Inherited human genetic disorders

IV. INHERITED HUMAN GENETIC DISORDERS B. Types of Inherited Genetic Disorders 1. Autosomal Genetic Disorders – Gene mutation is on any chromosome other than sex chromosomes ________ 2. Sex-Linked Disorders – Mutated gene is on X the ____ chromosome.

VI. GENETIC DISORDERS - AUTOSOMAL DISORDERS l l l autosomes Most genes are carried on the ______, 44 ______ chromosomes other than the sex chromosomes. autosomal Most genetic disorders are ______ disorders. These disorders affect males and females equally gene ____ and are due to _____ mutations.

Autosomal disorders can be divided into three groups based on the pattern of inheritance. 1. Autosomal Recessive 2. Autosomal Co-Dominant 3. Autosomal Dominant

A. Autosomal Recessive Disorders (pp. 297) l 1. Albinism – Characterized by failure to produce pigment, _____. Affected melanin eyes skin individuals lack coloration in ______, and _____. Very susceptible to ______. hair UV light Normal Symptoms appear _____; _____ life at birth expectancy

A. Autosomal Recessive Disorders 2. Cystic Fibrosis – Characterized by excess mucus production _________in _______, _____system. lungs digestive Symptoms appear just after birth and include frequent respiratory infections, poor nutrition. With treatment, patients can survive to young adulthood. Cystic fibrosis is the fatal most common _______ genetic disorder in the ____ United States among Caucasians. l

B. Autosomal Co-Dominant Disorders (pp. 303) Sickle cell anemia is an autosomal cohemoglobin dominant disorder that affects _____ production. oxygen Hemoglobin is the protein that binds ____ to red blood cells. 1.

Sickle cell Anemia l Individuals with the normal genotype, AA, do not have the sickle cell allele and produce only normal Hemoglobin.

Sickle cell Anemia Individuals that are SS produce abnormal hemoglobin that causes the red blood cells to “sickle” when oxygen availability is decreased; – for example, in high altitudes or during periods of stress. Sickled RBCs are more fragile, easily destroyed – results in energy ATP lack of ____ due to decreased _____ production in cells, blockage of blood vessels, and severe pain. Shortened life expectancy. Most common inherited disease African in individuals of ______ ancestry.

Sickle cell Anemia l Heterozygotes (AS) produce both normal and abnormal hemoglobin and are said to have ________. They do not show symptoms of sickle cell trait the disorder. In certain areas, individuals with sickle cell trait have a benefit over individuals that lack the sickle cell allele because they are resistant to malaria _______. Malaria is a serious, sometimes fatal mosquitoes disease spread by _____ that affects millions of people each year in _______. This increased Africa malarial resistance has resulted in a very high incidence of AS individuals. If two heterozygotes 25 marry and have children, they have a ___% chance of having a child with sickle cell anemia.

C. Autosomal Dominant Disorders (pp. 298) 1. Huntington’s Disease – Fatal genetic disorder in which symptoms do not show until 30 s to 40 s _______. Characterized by deterioration of _______. nervous system Dwarfism 2. Achondroplasia - ______

V. GENETIC DISORDERS - SEXLINKED DISORDERS (pp. 305 -308) A. Sex-Linked Inheritance l “Sex-linked” if it is located on a sex X or Y chromosome (______). l In humans, sex-linked genes are almost X always located on the larger ___ chromosome. Y – The __ chromosome is much smaller and carries only a few genes related to male sexual development ____________.

A. Sex-Linked Inheritance (pp. 305 -308) l l 2 Females have __ X chromosomes; one males have ____. Females will only show recessive traits located on the X homozygous recessive chromosome if they are ____________. Males will always show a recessive trait located on the one X chromosome because he only has _____ X chromosome, – genes so all _______ on the X chromosome will show. males having a much higher This results in _____ incidence of sex-linked disorders.

A. Sex-Linked Inheritance 1. Genotypes for sex-linked traits are written using the X and Y chromosomes to show path of inheritance. – – – For example, male-pattern baldness is a sex-linked recessive trait. If H = normal head of hair and h = baldness, h h h X Y bald male = _____; bald female = _____. X X carriers Females can be _______ for sex-linked recessive disorders. it does not show A carrier has the defective allele, but _______. H h The genotype of a female carrier is ______. X X cannot be carriers for sex-linked traits because Males _______ their 2 nd sex chromosome is the naked Y _______!

2. Sex-Linked Punnett Squares In sex-linked traits, probabilities for male and female offspring must be calculated separately because traits are inherited differently ________. If a man with a full head of hair marries a woman who is heterozygous, what is the probability they would have a son who would go bald? A daughter?

Sex-Linked Punnett Squares. If a man with a full head of hair marries a woman who is heterozygous, what is the probability they would have a son who would go bald? A daughter? Key: _________ Cross: _________ l Probability of bald daughter = ____ Probability of bald son= ______

B. Sex-Linked Disorders All of these disorders are sex-linked recessive __________. 1. Color Blindness – Inability to differentiate and distinguish colors __________.

Results For Ishihara Test(above) Normal Color Vision Red-Green Color Blind Left Right Top 25 29 Top 25 Spots Middle 45 56 Middle Spots 56 Bottom 6 8 Bottom Spots

B. Sex-Linked Disorders 2. Hemophilia – Missing an enzyme required blood clotting for normal ______ - results in uncontrolled bleeding ___________. Treated with blood transfusions, injections of missing factor.

B. Sex-Linked Disorders 3. Duchenne’s Muscular Dystrophy – Symptoms develop at ______. 3 -6 years Muscles weaken, break down __________, leading to eventual death. No available treatment cure _____ or ______. Death usually occurs before adulthood.

Examples: A colorblind female marries a man with normal vision. What is the probability of colorblind children? Key: _______ Cross: _______ 1. Probability of colorblind daughter: _______ Probability of colorblind son: ____

2. A genetics counselor interviews a couple with a family history of hemophilia to evaluate the possibility of offspring with the disorder. The woman does not have hemophilia, but states that her father had the disorder. The man is normal. Key: _______ Cross: ______ Son with: _____ daughter with: ______

III. ANALYSIS OF HUMAN INHERITANCE A. Punnett Squares & Multiple Alleles (pp. 304) more than 2 1. multiple alleles; that is, ______ alleles. An example of this is ABO blood groups. 3 There are ____ alleles for this gene. Two of the alleles, _______ are co-dominant, meaning A and B they always show _______ if present. The third allele, ____, is recessive, meaning it will only show if i (o) the genotype is ___. ii –

. Punnett Squares & Multiple Alleles l 2 Each individual inherits ___ alleles for this gene, one from _____ and one mom dad from ____.

Punnett Squares & Multiple Alleles The possibilities for blood group genotypes and phenotypes are: Phenotypes Genotypes A A A I I or I i Type A blood _______ B B B Type B blood _______ I I or I i A B I I Type AB blood _______ ii Type O blood _______

l Complete ABO Blood Type Punnetts in Notes packet