Presentation on theme: "Human Heredity l How does a mutation occur? l A chromosome or specific gene is damaged. l If a mutation occurs in one of the gamete cells it’s called a."— Presentation transcript:
Human Heredity l How does a mutation occur? l A chromosome or specific gene is damaged. l If a mutation occurs in one of the gamete cells it’s called a germ cell mutation. l If a mutation takes place in a 2N cell it’s called a somatic mutation. l Most mutations decrease from 1 generation to the next. l It is truly a miracle to be born a healthy baby; everything has to form just right during mitosis.
4 main types of chromosome mutations l1l1. Deletion – is where a chromosome is broken off so that all the information is lost. l2l2. Inversion - is where a chromosome piece breaks off and reattaches the opposite way it was attached before it broke off. l3l3. Translocation – is where a broken piece of chromosome attaches itself to a different chromosome from which it was attached.
l4l4. Nondisjuction – this is where a chromosome doesn’t separate right during cell division. One daughter cell receives 1 more chromosome than the other daughter cell. lWlWhat is a mutation? lAlA sudden genetic change. lElExamples of gene mutations: l1l1. A gene is not copied correctly l2l2. Chromosome problems l3l3. Environmental influence - radiation
lWlWhat is a mutant? lOlOrganism showing a mutation lWlWhat is a mutagen? lAlA substance that causes a mutation lAlAn Ames test is used to identify mutagens. lWlWhat are some causes of mutations? lRlRadiation from sun, x-rays, nuclear lSlSmoke, chemicals, smog, etc.. lClCancer
lTlThomas Morgan was a famous geneticist who studied fruit flies to determine the relationship between chromosomes and inheritance patterns. lFlFruit flies were easy to study, since they only have 8 chromosomes. lMlMorgan discovered that all the female fruit flies had homologous chromosomes. XX- sex chromosomes. lHlHe then figured out the males had a heterozygous chromosome (XY). lAlAll the other chromosomes besides the sex chromosomes are called Autosomes.
lSlSex-linked traits are influence by the X of the sex chromosome. Remember males have 1 X & females have 2. lMlMorgan discovered that mainly male fruit flies had white eyes. This is a sex- linked trait. lFlF1 Gen. X R X R x X r Y lHlHomozygous Dominant X Homozygous Recessive lFlF2 Gen. X R X r x X R Y
Applied Genetics lTlThe start of genetics and how it got started. lHlHunters & gatherers were the 1 st humans to use primitive genetics. lNlNomadic people of 20 to 50. lMlMen hunted and the women gathered. lAlAbout 10,000 to 12,000 years ago lTlTheir nomadic lifestyle changed when the agricultural revolution started; this required to stay in one place.
Things that cause a genetic change l1l1. They started to domesticate crops – they grew them instead of gathering them l2l2. Domesticated animals. l3l3. Build houses – no longer nomadic l4l4. The soil was starting to lose nutrients. l5l5. Waste was starting to build up lHlHumans had to change crops and animals genetically in order to stay in one place and provide enough food to stay in one place.
lAlApplied genetics came along because of this change in lifestyle. lAlApplied genetics is the altering or controlling genetics to suit our needs. lClControl breeding for desired traits lElEx. Beef and grain production lMlMass selection is where the parents are selected from a large number of possibilities.
lIlInbreeding is the mating of close relatives. lMlMutations may occur more frequently. l2l20 to 30% of all albinos are produced in marriages of relatives lHlHybridization is the crossing of 2 different, but similar organisms. lElEx. Liger (tiger & lion), Beefalo (buffalo & cow)
lHlHybrid vigor is having the best traits of both parents. lHlHybrids are usually sterile (chromosomes are similar) lPlPolyploidy is where an organism has more than 1 complete set of chromosomes. lElEx. Strawberries, tomatoes, wheat lElEx. Wheat 14 to 28 to 42 chromosomes
lClCloning – making exact copies of the parent organism. l1l1 st done in plants. lNlNow in sheep, mice, and possibly humans. lGlGenetic engineering – manipulating genes. Taking genes from one organism and putting them into another organism. lGlGene splicing – take a gene from 1 organism & put it in a DNA of another organism. lTlThis comes from a plasmid (circular ring of DNA in bacteria).
lRlRecombinant DNA – DNA segments from at least 2 different organisms. lVlVideo lAlApplications of Recombinant DNA l1l1. Insulin – made for diabetics l2l2. Interferon – protein produced by humans to stop the reproduction of viruses. l3l3. Oil eating bacteria l4l4. Disease resistant plant crops l Test tube baby – remove egg from mother and fertilize with sperm of the father. lSlSurrogate mother
Genetic Disorders lAlA group of genes located on a chromosomes is a linkage group. lVlVideo – genetic disorders lRlRed-green color blindness is an example of a sex-linked disorder in which the disorder occurs on the X chromosome. lOlOccurs mainly in males. Why? lMlMales only have 1 X, so they either carry it or don’t. lGlGenotypes: X C X C (normal), X C X c (carrier), X c X c (color blind female), X C Y (normal), X c Y (color blind male). lVlVideo – Manipulating genes
l Color-blindness occurs in 8% of males and about 1% of females. l Hemophilia (bleeders disease) – blood doesn’t clot properly. l 1 st discovered in Queen Victoria l Inherited same as red-green color blindness (sex-linked) l 1 in every 10,000 born have hemophilia l These people lack factor VIII in their blood, which helps clot the blood.
lSlSex influence traits are influenced by sex hormones produced by the individuals. lElEx. Baldness occurs more with the hormone testosterone. lElEx. Harelip (cleft palate) testosterone (males) lElEx. Spinalbifida estrogen (females)
l Chromosomal Disorders l Usually caused by nondisjunction – a failure of chromosome pairs to separate properly during meiosis. l 1. Monosomy – missing a chromosome (22 + 23 = 45) l 2. Trisomy – one more chromosome (24 + 23 = 47)
lDlDown Syndrome – caused by an extra chromosome on the 21 st chromosome pair. lTlTrisomy on the 21 st chromosome pair l4l47 total chromosomes lOlOccurs in about every 1 in 600 births lTlTurner’s Syndrome – a sex chromosome in a female is missing. lElEx. XX – normal, X – Turner’s Syndrome lUlUndeveloped female
lKlKleifelter’s Syndrome – an extra X sex chromosome in males. lElEx. XXY lPlPoorly developed male lJlJacobs’ Syndrome – an extra Y sex chromosome in males. lElEx. XYY l“l“Normal Male”
l Amniocentesis is used by physicians to determine birth defects. They use a needle and syringe to remove some amniotic fluid from the mother’s amniotic sac that surrounds the fetus. l Why is not used as much as ultrasound? l Ultrasound uses high-frequency sound waves that bounce off the fetus to form an image.
l Population sampling is where researchers use a small number of individuals to represent the whole population. l Gene pool – all the genes in a given population. l Gene frequency – the number of times a gene occurs in a population.
lTlTypes of Twins l1l1. Fraternal twins – develop from 2 fertilized eggs. lNlNot identical – can get a boy and a girl lOlOccurs in about 1 in every 100 births lMlMost likely to occur in 35 – 40 year old mothers. lTlTends to run in families l2l2. Identical twins – develop from a single fertilized egg. lTlThey have the same DNA
Other Genetic Disorders l PKU (phenylketonuria) – a genetic disease due to a “bad” gene (phenylalanine hydroxylase). l This person is unable to produce a certain enzyme. l This causes damage to the nervous system. l Sickle-cell Anemia – genetic disease of mainly blacks. Abnormal hemoglobin impairs the flow of oxygen to the body. l 9% of U.S. blacks have this; 40% of Africans have it.
lHlHuntington Disease – occurs in a autosomal dominant alleles of a trait. lClCauses loss of muscle control lClCystic Fibrosis – most common lethal genetic disorder among white Americans. lHlHave trouble digesting food and breathing
Blood Types l Antigens determine a person’s blood type l A, B, AB, O l Video Video l Red blood cells are covered with an antigen l Plasma is the liquid that contains an antibody which reacts with antigens. l Blood type antigens l 1. Type A Ia or Ia Io l 2. Type B Ib or Ib Io l 3. Type AB Ia Ib l 4. Type O Io
lTlType A can receive blood from A or O. It can donate to A or AB. lTlType B can receive blood from B or O. It can donate to B or AB. lTlType AB can receive from A, B, AB, or O (universal receiver). It can donate to AB lTlType O can receive from O. It can donate to A, B, AB, or O (universal donor).
l Mixing the wrong type of blood causes the cells to clump together or agglutinate. l Rh factor – protein found in RBCs l Found 1 st in the rhesus monkey l 87% of white U.S. population has the protein (+). l 13% lack this protein (-).
l Polygenetic trait – more than two genes determine the trait. l Ex. Skin color – melanin (pigment in skin) l Albinism – no melanin l P1P1 & P2P2 – darkest melanin l P1p1 & P2p2 – medium melanin l p1p1 & p2p2 – no melanin