Two copies of each autosomal gene affect phenotype (physical). Mendel studied autosomal gene traits, like hair texture. Autosome – chromosome with genes not related to sex of organism (body cells)

Karyotype The arrangement of all the chromosomes found in a cell. Includes: 23 rd pair Female sex chromosomes X X Female = Male = Sex Chromosomes: chromosome pair 23 Autosomes: chromosome pairs 1-22 X X Y

FEMALE MALE Sex Chromosomes (they determine male or female) “Autosomes”

Who determines the sex of the offspring? XX XY Sperm Body Cell XX X X X Y Y X X X 1female:1male Father – he can provide an X or Y chromosome Egg

–Carrier – has an allele for as trait or disease that is not expressed. –Carrier does not have disease symptoms but can pass it on to offspring. (dominant) Dominant allele disorders are rare. Huntington’s disease is an example of a disease caused by a dominant allele.

. Genes on sex chromosomes are called sex-linked genes. –Y chromosome - male characteristics. –X chromosome - genes affects many traits. Males can pass on X or Y Females only pass on X

1. Genetic disorder found on the sex chromosome X 2.Known as a “sex-linked” because its found on chromosome 23 3.Can’t distinguish between colors 4.More boys, than girls, are color blind…..WHY? Sex-linked disorder: Color Blindness

XCXC XCXC XCXC Y XCXC XCXC XCXC XCXC XCXC XCXC YY Color blind Dad and Normal mother produces…. XCXC XCXC XCXC Y XCXC XCXC XCXC XCXC XCXC XCXC YY Normal Dad and Carrier mother produces…. What is the only way to get a color-blind daughter?? Two normal sons 2 “carrier” daughters (NOT color blind) 1 color blind son, 1 normal son 1 “carrier” daughter, 1 normal daughter Sex-linked disorder: Color Blindness

1. Recessive genetic disorder found on the sex chromosome X 2.Disease in which blood doesn’t clot properly. Sex-linked disorder: Hemophila

XHXH XHXH XhXh Y XHXH XhXh XhXh XHXH XHXH XHXH YY Affected dad and Normal Mother produces…. XHXH XhXh XHXH Y XHXH XHXH XhXh XHXH XhXh XHXH YY Normal Father and Carrier Mother produces…. What cross will ALWAYS yield you 100% affected sons? Two normal sons 2 “carrier” daughters 1 color blind son, 1 normal son 1 “carrier” daughter, 1 normal daughter Sex-linked disorder: Hemophila

Males have an XY genotype. –All of a male’s sex-linked genes are expressed. –Males have no second copies of sex-linked genes –Y chromosome is much smaller

Females have an XX genotype. X chromosome inactivation -randomly “turns off” one X chromosome. Why are males more likely to than females to have genetic disorders? All sex-linked genes are expressed, even recessive. Females have a backup X chromosome.

Some traits are neither totally dominant nor totally recessive. Incomplete dominance - when neither gene is totally dominant to the other - Heterozygous phenotype is intermediate between the two homozygous phenotypes –Example: White flowers and red flowers produce pink flowers

Disease in which the body makes sickle-shaped red blood cells. Sickle-shaped cells don’t move easily through your blood vessels. They’re stiff and sticky and tend to form clumps and get stuck in the blood vessels. The disorder is found on chromosome 11 and is therefore not sex-linked. The Oxygen carrying hemoglobin can not carry oxygen as efficiently and the odd-shaped cells can easily clot and break. Fatigue, pain, and organ failure due to lack of oxygen supply are common symptoms of sickle cell anemia. It is common in the African community Sickle Cell Anemia Actual blood cells

Sickle Cell Anemia Codominance Practice Genes for blood cells: R = Round blood cells R’ = Sickle Cells RR RR’ R’R’ R R’ R Genotypes for blood cells RR = normal blood RR’ = some sickle cells, some normal cells R’R’ = has sickle cell anemia

Complete the following crosses, Report the genotypes and phenotypes of the offspring R = round blood cell R’ = sickle cell R R’ = carrier RR R’ R R R R R’ R R R’ Round Blood Cells x Hybrid x Mixed Cells x Hybrid x R’ R R’ R R’ Round Blood Cells x Sickle Sickle Cell Anemia x Pure Round x EXPECTED RESULTS EXPECTED RESULTS EXPECTED RESULTS EXPECTED RESULTS sickle cell anemia 2 mixed cells 1 normal cells 2 mixed cells 2 normal cells 1 sickle cell anemia 2 mixed cells 1 normal cells 1 sickle cell anemia 2 mixed cells 1 normal cells

Incomplete dominance Red White X Pink. There is a third color that exists in the heterozygous type. It’s a mixture between the two homozygous types.

Color blindness is a problem in which red or green look like shades of gray or other colors. The gene is carried on the X chromosome and is a recessive trait. X C X C X C X c X C Y X c Y XCXC XcXc XCXC Y X C X C = normal female X C X c = female, normal vision (carrier) X C Y = normal vision male X c Y = color blind male

Codominant - alleles will both be completely expressed. –Codominant alleles are neither dominant nor recessive. –The ABO blood types result from codominant alleles. Many genes have more than two alleles. Example – red and white flower produce a flower with BOTH colors

1. Blood Type there are _________________________ 4 different blood types Blood TypeGenes Blood Type AA A or A O Blood Type BB B or B O Blood Type ABA B Blood Type OO

Which blood types are compatible for transfusion?? OB Yes or No ? BA AA B A O Yes No Yes No Yes

AA B B AO B O AB A B AB O O OO A O AO A O AB BO AOOO AAAB BB AO BO OO AA

Blood type statistics… If there are 100 people in the room: 39 will be O+ 7 will be O- 34 will be A+ 6 will be A- 9 will be B+ 2 will be B- 3 will be AB+ and only 1 in 200 will be AB- Note: The + and – is the presence (or absence) of a third antigen (Rh).

Polygenic traits are produced by two or more genes. Order of dominance: brown > green > blue.

Epistatic gene - can interfere with the expression of all other genes. Mice have 5 genes that control fur color. 2 genes for general color 1 for shading 1 for spots 1 epistatic gene for color that overrrules all other genes

Height is an example of a phenotype strongly affected by the environmental factors such as early nutrition and health care. The sex of sea turtles depends on both genes and the environment. Warm eggs develop into females Phenotype is a combination of genotype and environment.

Gene linkage was explained through fruit flies. Morgan found that linked traits are on the same chromosome. Traits can be inherited as a group. Chromosomes, not genes, assort independently during meiosis. Wild type Mutant

Linked genes are not inherited together every time. Chromosomes exchange homologous genes during meiosis.

Linkage maps – map of location of genes on a chromosome. The closer together two genes are, the more likely they will be inherited together. Cross-over frequencies are related to distances between genes.

Cross-over frequencies can be converted into map units. – gene A and gene B cross over 6.0 percent of the time – gene B and gene C cross over 12.5 percent of the time – gene A and gene C cross over 18.5 percent of the time

Human genetics follows the patterns seen in other organisms. The basic principles of genetics are the same in all sexually reproducing organisms. –Inheritance of many human traits is complex. –Single-gene traits are important in understanding human genetics.

Females can carry sex-linked genetic disorders. Males (XY) express all of their sex linked genes. Expression of the disorder depends on which parent carries the allele and the sex of the child. X chromosome carries about 1100 genes while the Y carries about 250

Pedigree - chart for tracing genes in a family. Phenotypes are used to infer genotypes on a pedigree. Autosomal genes show different patterns on a pedigree than sex-linked genes. Widow’s peak: W = widow’s peak w = non widow’s peak

If the phenotype is more common in males, the gene is likely sex-linked. Colorblindness: M = normal vision m = colorblindness

Several methods help map human chromosomes. Karyotype - a picture of all chromosomes in a cell. X Y

FEMALE MALE Sex Chromosomes (they determine male or female) “Autosomes”

Amniocentesis A medical technique used to collect the chromosomes of a developing fetus. It is done by inserting a needle into the womb and gathering cells in the amniotic fluid.

Karyotypes can show changes in chromosomes. –deletion of part of a chromosome or loss of a chromosome –large changes in chromosomes –extra chromosomes or duplication of part of a chromosome