Biology Chapter 11 PDF

Chapter 11 Part 1 The larger a cell becomes, the less efficient it is in moving materials across its cell membrane. It also places increasing demand on its own DNA Surface area - the amount of “covering” of a object Formula - L x W x 6 = Xcm2 Volume - the amount of space inside a cell/object; the...

Chapter 11 Part 1 The larger a cell becomes, the less efficient it is in moving materials across its cell membrane. It also places increasing demand on its own DNA Surface area - the amount of “covering” of a object Formula - L x W x 6 = Xcm2 Volume - the amount of space inside a cell/object; the amount of space the object takes up. Formula - L x W X H = Xcm3 Ratio is SA:V Information Crisis - The bigger the cell, the more demand placed on DNA. Traffic Problems - Volume grows to fast relative t surface area, material exchange is insuffcient. Cell Division ​ It produces two daughter cells. ​ Cell must replicate DNA before cel division. ​ Dividing to make more, smaller cells keeps surface area to volume ratio high. Asexual Reproduction - A single parent produces genetically identical offspring Sexual Reproduction ​ Sexual reproduction involving the fusion of two speerate parent cells ​ Offspring inert ssome genetic information form each parent Comparing assexual and sexual reproduction Asexual -​ Produce many offspring in short period -​ Dont need tofind a mate -​ In stable environment genetically identical offspring thrive -​ If conditions change, offspring nt well adapted Sexual -​ Relatively fewer offspring; growth takes more time -​ Need to find a mate -​ In changing environments, genetic diversity can be beneficial -​ Offspring may be less well adapted to current conditions Part 2 Chromosomes ​ Where genetic information is bundled together in packages of DNA. ​ In prokaryotic cells, DNA is packaged into a single, circular chromosome; in Eukaryotic cells, DNA is packaged into multiple thread-like chromosomes. Prokaryotic Cell Cycle uses binary fission. Duplicate chromosomes then divide Eukaryotic cells have a more complex cell cycle. Interphase - time between cell divisions Mitosis - division of the nucleus Cytokinesis - Division of the cell G1 Phase (Cell Growth) - Cells do most of their growing during the G1 phase. Cells increasein size and make new proteins and organelles. S Phase (DNA Replication) - New DNA is made as the chromosomes are replicated. G2 Phase (Preparing for Cell Division) - Cell makes organelles and molecules needed for division. Usually shortest phase in interphase. M Phase - Cell division occurs during this stage -​ Prophase - The nucleus condenses and chromosomes become visible. The spindle begins to form. ​ Chromosomes - Condensed, duplicated chromosomes. ​ Centromere - point where each duplicated chromosome is attached to each other. ​ Centrioles - Organelle in animal cells where spindle fibers connect to form the spindle apparatus. -​ Metaphase - Chromosomes line up at the center of the cell. -​ Anaphase - Chromosomes move toward opposite poles -​ Telophase - The cell begins to divide into daughter cells -​ Cytokinesis - In animal cells, the cell membrane pinches in the center to form two daughter cell. In plant cells, cell plates form between the two nuclei and becomes the cell wall. Meiosis Every cell has chromosomes, the number of chromosomes depends on the species. Genes are located on chromosomes, genes control the traits of the individual. Chromosomes come in matching sets ​ These are called homologous pairs Cells in our body have a complete set, they are called diploid Sex cells only have half (23), they are called haploid When gametes combine, the zygite gets 23 chromosomes from mom, and 23 from dad. Zygotes are diploid (46) The process of creating sex cells is called Meiosis, it establishes 4 gametes/daughter cells. Oogenesis - makes eggs (ovum) Spermatogenesis - makes sperm The stages of meiosis occur in two divisions mitosis 1 and meiosis 2 -​ Homologous pairs join -​ crossing over - sections of chromosomes switching places, crossing genes. Independent assortment - different genes independently separate from one another during meiosis, the pairs of homologous chromosomes are divided in half to form haploid cells, and this separation, or assortment, of homologous chromosomes, is random Regulating the Cell Cycle The cell cycle is controlled by regulatory proteins inside and outside the cell. Cell Division and Repair Have to replace damaged cells through mitosis Healing a Bone ​ Cells at the edge of an injury are stimulated to divide rapidly ​ As an injury heals, the rate of cell division slows. The Discovery of Cyclins ​ Scientists found a protein in a ccell undergoing mitosis ​ They injected the protein into a non-dividing cell ​ A mitotic spindle started to form ​ Cyclins - proteins that regulate cell cycle Regulatory Proteins Internal regulators ​ Resond to events inside the cell ​ Let cell cycle proceed only when certain steps have already happened External Regulators ​ Respond to events outside the cell ​ Direct cells to speed up or slow down the cell cycle ​ Growth Factors -​ Wound healing and embryonic development -​ Stimulate the growth and divsion of cells Apoptosis ​ A process of programmed cell death ​ Important role in structing tissues during growth and development ​ Cell undergoes a series of controlled steps for self-destruction. Cancer ​ Cancer is a disorder in which the body cells lose the ability to control growth. ​ Caner cells dont respond to normal regulatory signals. ​ Cell cycle is disrupted. ​ Cells grow and divide uncontrollably. ​ Tumor - mass of cells -​ Not all tumors are cancerous -​ Noncancerous tumor are called benign. They do not spread to surrounding healthy tissue or other parts of the body. ​ In all cancers, control over the cell cycle has broken down. ​ Cancer results from a defect in genes (mutation) that control cell growth and division ​ Carcinogens - things that are know to cause cancer Treatments for Cancer Surgery to remove localized tumor, radiation to destroy canncer cell DNA, chemotherapy to kill cancer cels or slow their growth, immunotheraooy stimulates the body’s own immune cells to attack the cancerous cells.