UNIT 8 THE HUMAN GENOME Quiz 1 312

UNIT 8 – THE HUMAN GENOME Quiz 1 -31/2 -1 Test

I. HUMAN GENETICS (pp. 341 -343) A. Human Somatic Cells body Human somatic cells (____ cells) are ______ or __. Each cell contains ___ diploid 2 n 46 23 chromosomes, or ___ pairs of chromosomes. Of these pairs of 22 chromosomes, ___ pairs are homologous ______ pairs, meaning they contain the same genes in the same order.

A. Human Somatic Cells The 44 chromosomes that make up the 22 homologous pairs in each cell are autosomes called _____. The 23 rd pair of chromosomes are the ____ sex chromosomes. In female somatic XX cells, the sex chromosomes are ___; in a male’s cells, the sex chromosomes XY are ___.

B. Human Gametes are _______, or __, and contain haploid 23 ___ chromosomes. Female gametes are _____ cells and male gametes are egg sperm ______cells. Gametes are produced meiosis through the process of ____ in the testes _______ or ______, respectively. ovaries

B. Human Gametes homologous In meiosis, when the ______ pairs of chromosomes separate in ______, the anaphase I sex chromosomes separate also. The resulting egg cell can only contain an __ X chromosome, while the sperm cell produced 50 Y has a ___% chance of containing a ___ and a ___% chance of containing an __. 50 X male Therefore, the _____ determines the sex of the offspring.

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

Nondisjunction l l l In Anaphase I if homologous pairs do not separate correctly In Anaphase II if sister chromatids do not separate correctly In either case, Gametes are produced with an abnormal number of chromosomes. Number disorders are not inherited; therefore, they cannot be predicted with Punnett squares.

C. Analyzing Human Chromosome Numbers 2. Karyotypes - A karyotype is a photograph of __________. chromosome pairs Cells from the developing embryo or individual being tested are cultured in a nutrient growth medium, and then chemically treated to stop mitosis _____ in metaphase. The cells are stained, the chromosomes 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. Karyotypes number can only be used to detect _____ disorders and to determine the gender ____ of an unborn child.

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. 352, 353) A. Autosomal Number Disorders Most autosomal number disorders are lethal _____. 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 is also known as trisomy 21 _____ because there are 3 21 st ___ chromosomes at the ____ 2 position, instead of _______.

Down Syndrome

Autosomal Number Disorders Down syndrome Individuals have characteristic facial features; growth, behavior, and mental development are all affected. There is also a higher risk of _____ heart congenital defects. The incidence of babies with Down syndrome is much higher in older ______ mothers.

Patau Syndrome (Trisomy 13)

Trisomy 13 l l l l Cleft lip or palate Clenched hands (with outer fingers on top of the inner fingers) Close-set eyes -- eyes may actually fuse together into one Extra fingers or toes (polydactyly) Hole, split, or cleft in the iris (coloboma) Low-set ears Mental retardation, severe Scalp defects (missing skin) Seizures Single palmar crease Skeletal (limb) abnormalities Small head (microcephaly) Can have 3 types – – – One extra 13 th chromosome in all cells Trisomy 13 mosaicism-Extra 13 only in some cells, caused by mitosis after fertilization Partial Trisomy-due to translocation presence of a part of extra chromosome 13 in all cells

Edwards or Trisomy 18

Edward’s Syndrome (Trisomy 18) l l l l Symptoms Clenched hands Crossed legs (preferred position) Feet with a rounded bottom (rocker-bottom feet) Low birth weight Low-set ears Mental deficiency Small head (microcephaly) Small jaw (micrognathia) Underdeveloped fingernails Undescended testicle Unusual shaped chest (pectus carinatum. Trisomy 18 is a relatively common syndrome. It is three times more common in girls than boys. The syndrome is caused by the presence of extra material from chromosome 18. The extra material interferes with normal development. Can also be Full Trisomy 18, Partial Trisomy 18, or Mosaicism

Is there a problem with this karyotype?

B. Sex Chromosome Number Disorders 1. Turner Syndrome 45 XO Also called ______ because individuals 2 nd sex chromosome lack _________. Affected individuals are _______, typically short female in stature, underdeveloped sexually, with a normal life expectancy. * Generally infertile

Turner’s Syndrome

Does this individual have a number disorder?

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

l Klienfelter’s Syndrome

III. ANALYSIS OF HUMAN INHERITANCE A. Punnett Squares & Multiple Alleles (pp. 345 -346) A multiple alleles gene has that is, more than 2 ______ alleles. An example of this is 3 ABO blood groups. There are ____ alleles for this gene.

. Punnett Squares & Multiple Alleles (pp. 345 -346) A and B _______ are co-dominant, meaning they always show _______ if present. The third i (o) allele, ____, is recessive, meaning it ii will only show if the genotype is ___.

ABO Blood Types

Punnett Squares & Multiple Alleles (pp. 345 -346) 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 _______

B. Pedigrees l l l A pedigree is a diagram that follows the trait inheritance of a single _____ through several generations ______ of a family. squares males are represented by ____ and females, by _______. circles Individuals with the trait are represented shaded with ____ figures.

B. Pedigrees parents Vertical lines connect _______ and children _______. Horizontal lines connect spouses siblings _____ or _____. birth order l Children are placed in _____, left to right from _____. l

IV. INHERITED HUMAN GENETIC DISORDERS A. Gene Mutations Inherited human genetic disorders are the result of gene mutations; that is, a change in the DNA sequence of the gene _______________.

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

V. GENETIC DISORDERS - SEXLINKED DISORDERS A. Sex-Linked Inheritance (pp. 350, 351) A gene is referred to as “sex-linked” if it is X or Y located on a sex chromosome (______). In humans, sex-linked genes are almost always X located on the larger ___ chromosome. The Y __ chromosome is much smaller and carries only a few genes related to male sexual development _____________.

A. Sex-Linked Inheritance (pp. 350, 351) Females have __ X chromosomes; males have ____. 2 one Females will only show recessive traits located on the X chromosome if they are ___________. But a male will always homozygous recessive show a recessive trait located on the X chromosome one because he only has _____ X chromosome, so all genes _______ 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 l l Genotypes for sex-linked traits are written using the X and Y chromosomes to show path of inheritance. Male-pattern baldness is a sex-linked recessive trait. If H = normal head of hair and h = baldness – – – h h h bald male = _____; bald female = _____. X Y X X carriers Females can be _______ for sex-linked recessive disorders. A carrier has the defective allele, but _______. it does not show The genotype of a female carrier is ______. H h X X _______ be carriers for sex-linked traits because Males cannot their 2 nd sex chromosome is the _______! naked Y

Male Baldness

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?

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 – l Missing an enzyme required for blood clotting normal ______ - uncontrolled bleeding l results in ______ l Treated with blood transfusions, injections of missing factor.

Gene Therapy for Hemophilia

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

DMD

VI. GENETIC DISORDERS - AUTOSOMAL DISORDERS (pp. 345 -348) Most genes are carried on the ______, autosomes 44 ______ chromosomes other than the sex chromosomes. These disorders affect males and females ____ and are due to _____ equally mutations. Autosomal disorders can be gene divided into three groups based on the pattern of inheritance.

Autosomal Recessive Disorderd 1. Albinism Characterized by failure to melanin produce pigment, _______ UV rays 2. Very susceptible to _________ 1.

Autosomal Recessive Disorders l Cystic Fibrosis – – mucus lungs Characterized by excess ________ in ____, _________system. digestive Symptoms appear just after birth and include frequent respiratory infections poor nutrition. With treatment, patients can survive into adulthood. fatal Most common_______genetic disorder in the United States ____________ among Caucasians.

Cystic Fibrosis Gene

PKU Phenylketonuria or ____ l l l Characterized by an inability to breakdown the amino acid, ____________ Phenlyalanine If untreated, results in severe mental retardation All babies born in US hospitals are tested for PKU because it is easily treated with a diet proteins low in __________

Autosomal Co-Dominant Disorders l Sickle cell anemia is an autosomal co-dominant disorder that affects ________ production. Hemoglobin hemoglobin oxygen is the protein that binds _________ to red blood cells.

Sickle Cell Anemia 1. l AA Individuals with the normal genotype do not have the sickle cell allele and produce only normal hemoglobin.

Sickle Cell Anemia 2. SS l Sickle Cell Anemia l Produce abnormal hemoglobin that causes the red blood cells to “sickle” when oxygen availability is decreased; for example, in high altitudes or during period of stress. l Sickled RBCs are more fragile, easily destroyedenergy results in lack of ______due to decreased oxygen ________ in cells, blockage of blood vessels, and severe pain.

SS l l Shortened life expectancy. Most common inherited disease in individuals African of ________ ancestry.

3. AS l l heterozygous Described as ___________ Produce both normal and abnormal hemoglobin Do not typically show symptoms of the disorder. Heterozygote Advantage-Provides malaria resistance to _________

C. Autosomal Dominant Disorders 1. Huntington’s Disease l l Fatal genetic disorder in which symptoms do not Middle age show until ____________ Characterized by deterioration of m Mental functions and uncontrollable movements

Achondroplasia l l Dwarfism ________ (one form) Individuals with the homozygous dominant genotype do not live to birth; or die shortly after birth. Heterozygote genotype is the only viable genotype.

Marfan Syndrome l l Marfan syndrome- Dominant disorder that affects the connective tissue of the skeletal system, eyes, and circulatory system. Affected individuals have very long limbs, vision problems, and are susceptible to aortic rupture.

Marfan Syndrome