Two copies of each autosomal gene affect phenotype

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)

Several methods help map human chromosomes. • Karyotype - a picture of all chromosomes in a cell. XY

• 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

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

Write down three different statements you could use to describe the difference between autosomes and sex chromosomes. Process Box

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.

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

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

• 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

King Henry VIII is known for being ‘angry’ with his wives and blamed them for not producing a son. Explain why King Henry VIII should have found fault with himself. Process Box

• 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 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

Sex-linked disorder: Color Blindness 1. Genetic disorder found on the sex chromosome X 2. Known as a “sex-linked” because its found on chromosome 23 3. Normal Color Vision (N) = Dominant Colorblindness (n) = Recessive 2. Can’t distinguish between colors 3. More boys, than girls, are color blind…. . WHY?

• 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. XCXC = normal female XCXc = female, normal vision (carrier) XCY = normal vision male Xc. Y = color blind male XC XC Y Xc X CX C X CX c X CY Xc. Y

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

Sex-linked disorder: Hemophila 1. Recessive genetic disorder found on the sex chromosome X 2. Disease in which blood doesn’t clot properly. 3. Normal Blood Clotting (N) = Dominant Hemophila (n) = Recessive

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

– 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 allele disorders are rare. Huntington’s disease is an example of a disease caused by a dominant allele. (dominant)

• 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

Incomplete Dominance X Straight Curly Pink There is a third color that exists in the heterozygous type. It’s a. mixture between the two homozygous types.

Incomplete Dominance

Incomplete Dominance Incomplete dominance

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

Co-dominance Heterozygous type shows BOTH phenotypes exist TOGETHER

Co-dominance

Co-dominance

Sickle Cell Anemia • 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. and is therefore not sex-linked. 11 • 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 Actual blood cells

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

Complete the following crosses, Report the genotypes and phenotypes of the offspring R = round blood cell R’ = sickle shape RR: Round cells RR’ = sickle cell trait R’R’: sickle cell anemia Mixed Cells x Hybrid ----- x -----R’ R’ R R R’ R RR EXPECTED RESULTS 1 sickle cell anemia ------------- R’ R’ R 2 mixed cells -------------1 normal cells ------------- R RR RR Sickle Cell Anemia x Pure Round ----- x -----R’ R R R’ R’ R Round Blood Cells x Hybrid ----- x -----EXPECTED R R EXPECTED RESULTS 4 mixed cells -------------------------------------- RESULTS 2 -------------mixed cells 2 -------------normal cells ------------- Round Blood Cells x Sickle ----- x -----R’ R R’ R’ R EXPECTED RESULTS 4 -------------mixed cells --------------------------

1. Blood Type 4 different blood types • there are _____________ Blood Type Genes Blood Type A IAIA or IAi Blood Type B IBIB or IBi Blood Type AB IAIB Blood Type O ii

Which blood types are compatible for transfusion? ? Yes or No ? O B A AB B Yes A No AB Yes A No Yes O AB

IB IB IA IA IAIB IA IA IAIA IB IA i IAIB ___________ i IB IAIB IBIB i i IAi ii 4______ type AB blood IB ii i 1 -pure A blood ______ 2 -AB blood i 1 -pure B blood ______ IA ______ 2 -hetero A blood i 2 O blood ______ IA i IAIB IBi IAi ii IA IB IAi IBi IAIA IAi 1 -AB blood 1 -hetero A blood ______ 1 -hetero B blood 1 -pure O blood ___________ 2 -hetero A blood ______ 2 -hetero. B blood ______ IAi ii ______ 2 -hetero A blood ______ 2 - O blood

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 ABNote: 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

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

• 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

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

Some examples of human codominant traits include: blood groups: ABO, Duffy, Kell, Kidd, MNS, Rhesus red cell enzymes: acid phosphatase, adenylate kinase serum proteins: haptoglobulins cell surface antigen: human leucocyte antigen (HLA)