The Cell Cycle, Genetic Variation, Mendelian Genetics, And Complex Genetic Inheritance

In a cell cycle, there are specific checkpoints between each phases caused by the occurrence of cyclin. Cyclin determines how concentration flunctuatues. If the regulation is disrupted by a decreasein cyclin, there would be no mitosis, meaning the cell cycle would continuously go thre G0 phase. However, if there is an increase

Interphase: This particular stage is divided into three phases, G1 (first gap), S (synthesis), and G2 (second gap). During all three phases, the cell grows by producing proteins and other organelles within the cytoplasm. However, chromosomes are replicated only during the S phase. In all, a cell grows (G1), continues to grow as it duplicates its

A) Meiosis consists of two cell divisions and is broken up into Meiosis I and Meiosis II. At the beginning of the Cell Cycle, in this case there are four chromatids each from the homologous pairs being A, a, B, b. This is the Diploid number (4) meaning it is 2 times the haploid number that will be seen at the end of meiosis II. During the S phase of interphase, the chromatids replicate and reach the end of G2 phase. Now starting meiosis, during the first stage of prophase I the chromosomes condense and pair up through synapsis with their sister chromatids creating AA, aa, BB, bb. After they pair up they go through a process called crossing over, where the homologous chromosomes share a piece of their genetic material with each other. Crossing over allows for the genetic diversity of chromosomes. Now there are four homologous chromosomes Aa, Aa, Bb, Bb, each containing heterozygous alleles because the sister chromatids exchanged genetic information with their homologous pair. During late prophase I, spindle fibers being to form where they will later attach to a homologous chromosomes centromere. The next stage is Metaphase I. During metaphase I, the homologous pairs line up at the metaphase plate, also known to be the center of the cell. The homologous pairs form a tetrad which is considered a group of four homologous chromosomes. These homologous chromosomes orient themselves randomly, which is know as the process of independent

Without cell division and the cell cycle nearly all life would fail to exist. Cell division allows an organism to not only replace its own cells but to create offspring. The cell cycle consists of two main parts: interphase and mitotic phase. Within these two phases the processes can be broken down into further categories. Interphase can be broken down into three subphases that are the necessary preparations the cell makes in order to be ready to divide during mitosis. For this lab we looked mainly at the mitotic phase because of its fascinating and rapid changes to the cell. The cell types we looked at were prepared slides of whitefish and onion root tip.

The phase of mitosis proceeding anaphase in which two daughter cells are formed, their nuclei are formed, chromosomes unravel, and the cleavage furrow closes the gap between them and separates them (cytokinesis occurs).

Genetics can help answer questions about our traits and why we look different and advance in different ways from each other in the world. Chapter 1 explains the basics about how genes work, and the portrayal of DNA and RNA. Chapter 2 describes RNA more in detail and it consist of the explanation of the human genome. Specifically, Chapter 3 clarifies how evolution works and how it relates to genetic and medical research. Furthermore, Chapter 4 and 5 explains the knowledge researchers have about genes role in health and diseases, and how society is affected with the advances in medicine and science given approximate credit to these researchers.

The cell cycle has four main stages. The cell cycle is the regular pattern of growth. The four stages consist of Gap 1 (G1), Synthesis (S), Gap 2 (G2), and Mitosis (M). Gap 1, consists of a cell that carries its normal functions. Calls also increase in size, and the organelles increase in number. A cell will spend the most time in this phase. But it also depends on the cell type to see how long it will spend in this phase. During this phase the cell has to pass a critical checkpoint before it can continue into the (S) stage, also called the Synthesis stage. It would be dangerous for a cell to keep dividing if the certain conditions were not met. The cells in this stage also need signals from the other cells to tell the if division is needed. Now the next stage is the Synthesis stage. During this phase the cell makes a copy of it’s nuclear DNA. By the end of the (S) phase DNA appears grainy in photos and the cell nucleus contains two complete sets of DNA. Gap 2, is the third stage of the cell cycle. The cells continue doing there thing and more growth occurs. This phase is like the checkpoint, everything in the cell has to be going right for the cell to be able to enter mitosis.

Mitosis is one of two main methods of cell replication, the other being meiosis. It is “the simple duplication of a cell and all of its parts” resulting from the splitting of a cell. The ‘parent’ or original cell splits, duplicating its DNA (packaged in chromosomes) producing two ‘daughter’ or new cells with the same genetic code. There are four stages of mitosis; Prophase, Metaphase, Anaphase and Telophase. Interphase is not an official phase of mitosis as the cell is at ‘rest’ and not being divided during this phase. It is often called one of the phases of mitosis as it is one of the stages in the life cycle of a cell; however it is not a phase of mitosis due to the fact that no division takes place.

Gregor Johann Mendel, the father of genetics, was born in 1822. He was a priest and scientist who became famous for his work and studies on the inheritance patterns using pea plants. Gregor Mendel used pea plants known as Pisumsativum in his research where he developed two fundamental laws of genetics known today as the “Law of segregation”, and the “Law of independent assortment” (Hartl, 1992). The “Law of segregation” states that when an individual produces a gamete, the copies of a given gene separate in which each gamete receives only one copy of that gene. The phenotypic ratio in the F2 generation according to the “Law of

In genetics, the way people retrieve their genes and traits is through cell division; mitosis and meiosis. Mitosis in cell division is the process in making body cells. There are 7 stages in mitosis; interphase, prophase, prometaphase, metaphase, anaphase, telophase, and cytokinesis. In interphase, the cell is growing normally and synthesizes with organelles. In prophase, changes occur in the cell and parts of the structures begin to break down, setting the stage for chromosome division. Prometaphase is the stage where the chromosomes are sorted and made very compact, and metaphase is when the chromatids of each chromosome are attached to a microtube to form a spindle. Anaphase it the process in which the chromosomes split, leading into telophase, which is where the chromatids travel to opposite poles in a cell and new membranes form around the nuclei. The final stage in mitosis, cytokinesis, is when the chromatids split in two.

All cancers arise as a result of changes that have occurred in the DNA sequence of the cell genomes, occurring through chromosome abnormalities (Stratton, Campbell, and Futreal, 2009). Chromosomes are made up of tightly wound DNA and proteins which form a highly condensed tertiary structure. Chromosomal abnormalities are a prominent characteristic of cancer cells, often resulting from nondisjunction, the failure of chromosomes to separate properly during meiosis (Peña-Diaz et al., 2012). Nondisjunction results in cells that have too many or too few chromosomes. A normal human karyotype would contain forty-four autosomes and two sex chromosomes; each chromosome has a homologous pair. Females

Heredity – the transmission of traits from one generation to another, from parents to offspring; the protoplasmic continuity between parents and offspring

Interphase, also known as the, “resting stage” is the key phase of the cell cycle. This is where normal cell function and cell preparation begin. Cells will spend approximately 16 to 18 hours in this phase (Hay). It is sectioned into 3 phases: Gap 1 (G1), Synthesis (S), and Gap 2 (G2). During the Gap 1 phase, the cell resumes normal cell functions and growth. During the Synthesis phase, the chromosomes are replicated and sister chromatids are formed. During the Gap 2 phase,

It’s the metabolic activity phase and the cell just prepares itself to new division. And consist of 2 gaps (G1,G2) and DNA synthesis phase (S phase) (1)

The main focus of this lab was to be able to understand the different phases of mitosis and the cell cycle and also identify what those stages may look like. Mitosis is the process in which concerns the production of new cells. For example, when apoptosis(cell death) the process of Mitosis begins to replace the dead cells. To be able to familiarize ourselves with this concept, we took a sample of an onion root and had it put through a process to be able to look at the different phases under the microscope. We found that the majority of the cells were mostly undergoing Interphase or Prophase which are the phases in charge of crossing over of DNA and where the chromosomes then become visible and the nuclear envelope dissipates. The conclusion of this lab was that Mitosis is essential for the production of new cells. In the case of the onion root sample, the cells were damaged leading to the tester to undergo Mitotic cell division and it was found that mainly Interphase and Prophase were the stages that occurred in this lab.