Chapter 2 IB Biology
2.1 Cell Theory
2.1.1 Outline the cell theory (2).
• All organisms are composed of one or more cells
• Cells are the smallest units of life
• All cells come from preexisting cells
• TOK: cell theory replaces the former ideas of spontaneous generation or abiogenesis in which inanimate matter assembles itself into living forms • Exception: muscle cells- more than 1 nucleus, very long; (fungal cells) hyphae roots- not a single unit; protoctista- not specialized to single function; subcellular things like organelles 2.1.2 Discuss the evidence for the cell theory (3).
• Robert Hooke first described cells in 1665 while observing cork with a microscope he built. Coined the term “cell” • Antoine van Leeuwenhoek
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• As organisms grow, cells divide. 2 small cells are more efficient than one. • Alveoli in lungs maximize surface for gas exchange.
2.1.7 State that multicellular organisms show emergent properties (1). • Different things come together to make process
• Cells-tissues-organs-etc.
• Ability to reproduce themselves. Allows possibility of growth and for replacement of damaged or dead cells. 2.1.8 Explain that cells in multicellular organisms differentiate to carry out specialized functions by expressing some of their genes but not others (3). • Start out as single cell that reproduces at a rapid rate then the resulting cells go through a differentiation (different cells- different functions- to run an organism) process to produce all required cell types that are necessary for organism. • Every cell in a multicellular organism contains all the genes of that organism. However, the genes that are activated vary from cell to cell. • Differentiation- when we break something complex into its component pieces, they each appear to be simple. Combined, they can perform a whole new function. Cells within a multi cellular organism specialize their function. • Examples: muscles cells, cardiac cells
• This differentiation process is the result of the expression of certain specific genes but not others • Genes allow for the production of all different cells in the organism • Each cell contains all the genetic info for the production of the complete organism • Each
2. Define multicellular organism - are those organisms containing more than one cell, and having differentiated cells that perform various functions.
Without the cells there will be no life. A cell is the the building block of the body. There 2 different types of cells there are animal cell and plants cells. Eukaryote is any cell that has a cell membrane bound. It also contains organelles.
There are many parts of a cell, they all have specific duties, and are all
contrast the reasons cell division is important for unicellular and multicellular organisms. Cell division is the method in which single celled organisms reproduce. Cell division allows multi-cellular to grow and repair dead or damaged cells
Coelomates have an enclosed body cavity, which means advance muscle structure, enhanced locomotor capabilities, and more structural integrity.
The cell has the ability to reproduce, this ensure the continuation of the organism as cells regenerate and repair. There are two types of cell division:
The cell is the basic unit of life and is the smallest, simplest organism that can perform all of life’s functions. The cell was discovered in 1665 by Robert Hooke. The three types of cells are plant cells, animal cells, and prokaryotic cells. These cells share many qualities but are also different in many ways.
B. Growth – over a lifetime, organisms grow larger through an increase in size or number of cells. Differentiation is when cells have specialized functions
Cells are some of the smallest organisms around. All living things consist of cells, and yet they are invisible to the naked eye. Cells are the basic structural and functional units of life. Cells are made up of many different parts which allow them to function properly.
The cell is the smallest unit able to sustain life, and they are often referred to as the building blocks of life. There are two primary types of cell, which are categorized according to the way their genetic material is packaged, rather than size or shape. These are:
Genes come in different varieties, called alleles. Somatic cells contain two alleles for every gene, with one allele provided by each parent of an organism. Genotype refers to the information contained in an organisms DNA, or genetic material. Its phenotype is the physical
Gene expression is the ability of a gene to produce a biologically active protein. This process is regulated by the cells of an organism, it is very important to the survival of organisms at all levels. This is much more complex in eukaryotes than in prokaryotes. A major difference is the presence in eukaryotes of a nuclear membrane, which prevents the simultaneous transcription and translation that occurs in prokaryotes. Initiation of protein transcription is started by RNA polymerase. The activity of RNA polymerase is regulated by interaction with regulatory proteins; these proteins can act both positively, as activators, and negatively as repressors. An example of gene regulation in cells is the activity of the trp operon. The trp
Lets start by looking at the cell and the source of heritable traits. We know that all organisms are made up by cells and that new cells can only spring from existing cells. Cell growth depends upon the production of new cells and within each cell exists DNA. DNA contains the hereditary instructions need for each organism to grow and develop. Every
But first, let us talk about the discovery of cells and the cell theory. Robert Hooke, an english scientist, was the man who first discovered the cell in 1665, proof being a book he released at that time called Micrographia. In this book, Hooke gave 60 observations of random objects under a compound microscope with a magnification of 30x. Because of this, he was not able to see the internal structures in the cell, like nuclei and vacuoles, and what he proclaimed to be cells were just empty cell walls of plant tissues. He shared his observations with The English Royal Society, until they started receiving letters from a scientist named Anton van Leeuwenhoek. The letters stated that Anton made use of a microscope containing improved lenses that magnified objects up to 275x, enough to identify the living parts of a cell. He kept on sending
Cells, they are the building block of all life, they are what make up the entirety of living things on Earth and without them living things would cease to exist. It is because of this that cells are considered to be the most important known unit of life and are studied so often. Cells were first observed in the mid 17th century by English physicist and microscopist Robert Hooke using on of the earliest versions of the microscope. (Biologyreference.com, 2017) Hooke’s observations led to further investigations and studies into the topic of cells resulting in many major breakthroughs in the field of biology. Possibly the biggest of these breakthroughs is credited to have being made by Theodor schwann, Matthias Schleiden and Rudolph Virchow,