Genetics Biology S 2 Introduction video http viewpure

Genetics Biology – S 2

Introduction video http: //viewpure. com/17 fo. W 4 m. LBFk? start=0&e nd=0 Also on H: Drive

Mendel tested all 34 varieties of peas available to him through seed dealers. The garden peas were planted and studied for eight years. Each character studied had two distinct forms, such as tall or short plant height, or smooth or wrinkled seeds. Mendel's experiments used some 28, 000 pea plants. Some of Mendel’s pea traits he work with * FATHER OF GENETICS

Conclusions from Mendel's work 1) Individual factors control each trait (genes) the different forms a gene can take are called (alleles) 2) Principal of Dominance- some factors are dominant over others, which are called recessive The Monohybrid Cross- Mendel was curious as to what would happen if you crossed 2 different pea plants with contrasting traits

3) Law of Segregation- during gamete formation alleles are separated and each gamete carries only a single copy of each gene. "Peas Out" Mendel also wanted to know what happened to the recessive alleles? Had they disappeared? Were they still present in the F 1 plants?

Some Genetics Terminology necessary to understanding key concepts Purebred- 2 of the same alleles for a trait (Homozygous) Homo=same Hybrid- 2 different alleles for a trait (Heterozygous) Hetero=different Allele- different forms a gene can take Gene- part of a chromosome with DNA information Genotype- the genetic make-up of an organism, letters Genotypic Ratio- ratio, in numbers, of the possibilities of a genetic cross Phenotype- the physical characteristics of the possibilities of a genetic cross, what they look like Phenotypic Ratio- ratio, in numbers, of the different phenotypic possibilities

Independent Assortment After discovering the Principal of Segregation, Mendel wondered if gametes did so independently or did the traits have a tendency to be passed on together. It does matter if they are on the same chromosome however. R-smooth is dominant over constricted r Y-yellow is dominant over green g Two-factor Cross Dihybrid Cross He crossed two traits: shape and color

Gamete production in a two factor cross FOIL - gametes can be created by this method F-first 1&3 O-outside 1&4 I-inside 2&3 L-last 2&4 Ss. Yy 1234

Other methods of inheritance-important exceptions to Mendel's discoveries Incomplete Dominance- 2 or more alleles influence the phenotype of the offspring -flower color -like mixing colors

Co-dominance- both alleles are expressed in offspring - human blood types - coat colors in some mammals - checkered chickens Red Roan -sickle cell disease HR x HW HRW

ABO BLOOD TYPING: • Blood type AB is the most dominant • Blood type O is the most recessive

1) A man with heterozygous B type blood marries a women with heterozygous A blood. What are the chances of them having children with type A blood? _____, Type B blood? _______, O type blood? _______. 2) Determine the possible blood types from the mating of a person who is homozygous A blood type and a person who is heterozygous B blood type. 3) At a local hospital, Mr. and Mrs. Lump had a child at the same time as Mr. and Mrs. Bump. The Lumps had a boy and called him Bill, while the Bumps also had a boy and called him Tony. A few weeks past and the Bumps claimed the babies were switched. They sued the hospital and all 6 individuals were asked to get their blood tested. The results of the tests were: Mr. Lump had A type blood, his wife had B type blood, and Bill had A type blood. Mr. Bump tested for O type blood, his wife had AB blood, and Tony had O type blood. Was there a switch? _____.

Genetics and Probability- the likelihood that a particular event will occur Rules 1 you only get the expected outcome with large number of trials 2 previous events don't affect future results 3 independent events happening at the same time is a product of their probabilities- Product Rule Flipping coins- having children- it's all the same!

Meiosis Overview http: //viewpure. com/r. B_8 d. Tuh 73 c

Diploid Polyploid Tetrad & Crossing over Diploid Haploid Diploid- (2 n) refers to a complete set of chromosome (46 in humans) Haploid- (n) refers to ½ the normal set of chromosomes (human 23) Polyploid http: //highered. mcgraw-hill. com/sites/0072495855/student_view 0/chapter 2/animation__comparison_of_meiosis_and_mitosis__quiz_1_. html http: //highered. mcgraw-hill. com/sites/dl/free/0072835125/126997/animation 5. html

Meiosis- division of germ cells to create sex cells Spermatogenesis- creation of sperm cells in the male testes Adult males can produce approximately 100 million sperm cells/day

Oogenesis- creation of egg cells in the female ovaries derived from germ cells Polar Bodies are never fertilized

Mitosis vs. Meiosis Mitosis: • If a cell wants to make a duplicate of itself, it first must copy its DNA (part of a chromosome). • The copies then must be separated & sorted into two sides of the cell. • The cell then splits in two. Part of each parent is carried to the two new cells. • Results in cells such as internal organs, skin, bones, blood, etc. Meiosis: • As in mitosis, if a cell wants to make a duplicate of itself, it first must copy its DNA (part of a chromosome). • occurs in reproductive cells or gametes (sperm, eggs, ). • Part of each parent is carried to the four new cells. http: //viewpure. com/Ba 9 LX KH 2 zt. U

Meiosis Terminology: 1. Homologous chromosomes- pair of identical chromosomes (code for the same genes) 2. Diploid (2 N)- full set of chromosomes (46 chromosomes) 3. Haploid (N)- ½ set of chromosomes (23 chromosomes) 4. Tetrad-a pair of chromatids (4 chromosomes total)

Label the following structures: centrioles, nuclear membrane, spindle fibers, centromeres, tetrads

Prophase I spindle fiber centrioles aster fibers • Tetrads form • Crossing over (exchange of genetic material) occurs

Crossing over Tetrad nonsister chromatids chiasma: site of crossing variation

Metaphase I • Tetrads align on the metaphase plate • INDEPENDENT ASSORTMENT OCCURS: 1. Orientation of homologous pair to poles is random = genetic variation OR metaphase plate

Anaphase I • Spindle fibers pull homologous chromosomes apart

Telophase I • Each pole now has diploid set of chromosomes • Cytokinesis occurs and two diploid daughter cells are formed.

Meiosis II Prophase II • No interphase II (or very short - no more DNA replication) replication • same as prophase in mitosis

Metaphase II • same as metaphase in mitosis metaphase plate

Anaphase II • same as anaphase in mitosis • sister chromatids separate

Telophase II • Remember: four haploid daughter cells are produced.

Meiosis Overview

How does meiosis create genetic variation? 1. Crossing over- Prophase I, homologous chromosomes exchange pieces of genetic material 2. Independent assortment of chromosomes. Metaphase I, tetrads line up in the middle at random 3. Mutations- a change in genetic information 1. Deletion 2. Duplication 3. Inversion 4. Translocation 5. Insertion

Human Heredity- recent technological advances have let humans learn more about their inheritance than ever before. Examples: New high power microscopes, Human Genome project, gene mapping, karyotypes, and 23 andme Karyotype- a picture is taken of a cell in mitosis, where the chromosomes are condensed and they cut them and arrange into pairs 46 Chromosomes Sex Chromosomes are located at the end. 46 XX is female 46 XY is male

Non-disjunction- failure of chromosomes to separate properly during meiosis (AKA: meiosis gone bad)

Genetic Disorders Video http: //viewpure. com/8 s 4 he 3 w. Lgk. M

Trisomy 21 Downs Syndrome Maternal Age at Delivery Risk at Term 32 1/725 33 1/592 34 1/465 35 1/365 36 1/287 37 1/255 38 1/177 39 1/139 40 1/109 41 1/85 42 1/67 43 1/53 44 1/41 45 1/32 46 1/25 47 1/20 48 1/16 49 1/12 Autosomal (genetic chromosomes) Nondisjunction Disorders The result of an extra copy of chromosome 21. People with Down syndrome are 47, 21+. Down syndrome affects 1: 700 children and alters the child's phenotype either moderately or severely: ·characteristic facial features, short stature; heart defects ·susceptibility to respiratory disease, shorter lifespan ·prone to developing early Alzheimer's and leukemia ·often sexually underdeveloped and sterile, usually some degree of mental retardation. ·Down Syndrome is correlated with age of mother but can also be the result of non-disjunction of the father's chromosome 21.

Non-disjunction of Sex Chromosomes / X-Linked Genetic Disorders Turners Syndrome 1: 5000 live births; women with Turner's have only 45 chromosomes!!! XO individuals are genetically female, however, they do not mature sexually during puberty and are sterile. Short stature and normal intelligence. (98% of these fetuses die before birth) high hairline and some webbing of the neck.

Klinefelter's Syndrome 47 XXY Males. Male sex organs; unusually small testes, sterile. Breast enlargement and other feminine body characteristics. Normal intelligence. Affects 1: 500 to 1: 1000 males

How would you label these examples?

Sex-linked disorders- most are on X chromosome, some on Y Colorblindness and Hemophilia are Recessive disorders carried on the X chromosome Royal Pedigree showing Hemophilia

Methods of Inheritance of Hemophilia and Colorblindness

Why would this scenario be very hard to come by?

Are You Colorblind? Sex-Linked Traits: 1. Normal Color Vision: A: 29, B: 45, C: --, D: 26 2. Red-Green Color-Blind: A: 70, B: --, C: 5, D: -3. Red Color-blind: A: 70, B: --, C: 5, D: 6 4. Green Color-Blind: A: 70, B: --, C: 5, D: 2