Chapter 18 Rev.

MAJOR TOPIC TWO

Chapter 18 Review: Patterns of Chromosome Inheritance
1. Chromosomes and the Cell Cycle
Chromosomes occur in pairs in the body’s cells. A karyotype is a visual display of a person’s chromosome. A normal human karyotype shows 22 homologous pairs of autosomes and one pair of sex chrom. The normal sex chrom. In males is XY, and in females XX. The cell cycle occurs continually and has 4 stages to it. G1, S, G2, M. In G1 a cell doubles organelles and accumulates materials for DNA synthesis. In stage S DNA replication occurs. N G2, a cell synthesizes proteins needed for cell division.
2. Mitosis
This is the duplication division that assures that all body cells have the diploid number & the same kinds of chromosomes as the cell that divides. Prophase: Chromosomes attach to spindle fibers. Metaphase: They align at the equator. Anaphase: Chromatids separate, becoming chromosomes that move toward the poles. Telophase: Nuclear envelope form around chromosomes, cytokinesis begins. Cytokinesis is the division of cytoplasm and organelles following mitosis.
3. Meiosis
This involves two cell divisions, I and II. In stage I, homologous chromosomes pair and then separate. In stage II, sister Chromatids separate, resulting in four cells with the haploid number of chromosomes that move into daughter nuclei. Meiosis is a part of a gametogenesis.
4. Comparison of Meiosis and Mitosis
They are both nuclear divisions but there are several differences between them. Meiosis only occurs at a certain time in the life cycle of sexually reproducing organisms. The events of meioses II are just like those of mitosis except in meiosis II the nuclei contain the haploid number of chromosomes. Meiosis is a part of spermatogenesis the production of sperm in males, and oogenesis in the eggs of a female.
5. Chromosomes Inheritance
Meiosis is a part of gametogenesis and contributes to genetic diversity. Nondisjuction changes the chromosome number in gametes, resulting in trisom or monosomy. Autosomal syndromes include trisomy and Down syndrome. No disjunction during oogenesis can result in gametes that have too few or too many X or Y chromosomes. The syndromes names are: Turner, Klinefelter, poly-x, and Jacobs.

CHAPTER 18-22 PHOTO'S

Genetics Lab Write Up

In scarnerio 6 were crossed two flies also and got two differnt matches.

In Scenario5 here we were aked to cross two flies. Heterzygous and homozygous.

This is the results after i matched up the chromosomes to be identical.

This here represents the two different dragons that I have before matching up their chromosomes.

All genes are made up of DNA – the inherited genetic material passed on from one generation to the next that is found in all cells of the human body. Genes are responsible for how your body develops looks and works. Your genes are unique to you – nobody else has the same set of genes unless you have an identical twin. The two copies of the gene may be exactly the same or be slightly different versions, called alleles. Examples of alleles can be found in the genes for eye color and hair color. These genes are present in all people, but slightly different versions, or alleles, account for the variations seen in eye and hair color. Genotype is a term that refers to the individual's genetic makeup. Phenotype is a term that refers to the traits or features that a person displays. The relationship between genotype and phenotype is often complicated. Although a child has half his or her genetic information from each parent, he or she is not necessarily a simple combination of the parents' traits. This is because of the complex interaction between the two alleles for each gene, between different genes, and between genes and the environment. Genes run in families and are passed on to you from your parents - half of your genes have come from your mother and half from your father. This is how family resemblance and an increased risk of a disease running in the family are passed down from one generation to the next. Depending on the combination of genes you inherit you will end up with some traits that resemble your mother and others that resemble your father.While most characteristics and conditions have a complex genetic and environmental basis, there are a few traits or diseases for which the role of genes is well understood. In most cases, these traits or diseases are due to different alleles of a single gene. As described below, the alleles can be dominant or recessive. The concept of dominant and recessive alleles was first described in the 1860s by a monk named Gregor Mendel who studied the relationship between genotype and phenotype in pea plants. Therefore, traits or diseases which are due to single genes are sometimes called Mendelian.

We now discuss the Punnet Square Lab: In this discussion, cross dominate, recessive will be talked about. In this lab we were asked to cross two flies half of a heterozygous gray bodied and half of a homozygous gray bodied. ( Gg, GG). We were creating 2 new flies. In the creation the half homozygous fly had indentical matches of the body color. They were not alike but had alike skin tones. This is th GG fly. The other fly which is represented by Gg had two different colored skin flies. This occured because one fly was dominate which was letter G and the other recessive one (g).

Dragon Lab:In this lab we were given instructions to move and change several different genotypes, which meant changing the apperance of the dragon( phenotype. )While reading the interactive lab it noted that the dragons had different physical appereances because of their genotype. The chromosomes for the dragons were labeled with what they contorleed(ex: tail, fire, skin etc..). We were asked to match the two dragons until they were identical. In orderto do that all that i had to do was take a couple minutes to review Dragon 1's phenotype and and change Dragon 2's alleles until the two dragons became identical. Therefore without genetic inheritanc life would not be possible. Genetic inheretance happens when offspring of cells inherits different traits of the parents.