# data[].attributes.body
https://bit.ly/NotebookTemplates

# data[].attributes.attachment_link.description
Overview of 7th Grade Life Science Course in Savannah, Georgia. | Find thousands of free educational ebooks for classroom use at read.bookcreator.com

# data[].attributes.headline
Phenomena Brainstorm: Characteristics of Life

# data[].attributes.subject
Phenomena Brainstorm: Characteristics of Life

# data[].attributes.body
Shared Class Document: https://tinyurl.com/y3vs32xd

# data[].attributes.attachment_link.title
The wacky history of cell theory - Lauren Royal-Woods

# data[].attributes.body
https://bit.ly/CCCTemplates

# data[].attributes.body
High School Biology

# data[].attributes.attachment_link.description
A required part of this site couldn’t load. This may be due to a browser extension, network issues, or browser settings. Please check your connection, disable any ad blockers, or try using a different browser.

# data[].attributes.body
Template: https://tinyurl.com/y5kw4mfe

# data[].attributes.body
https://tinyurl.com/y54gw4g3

# data[].attributes.body
https://bit.ly/SEPTemplates

# data[].attributes.attachment_link.description
Learn about the basic properties of life as well as ongoing debates about the definition of life.

# data[].attributes.headline
Prokaryotic vs. Eukaryotic Cells: What's the Difference?

# data[].attributes.subject
Prokaryotic vs. Eukaryotic Cells: What's the Difference?

# data[].attributes.attachment_link.title
Prokaryotic vs. Eukaryotic Cells: What's the Difference?

# data[].attributes.attachment_link.description
Discover the structural and functional difference between prokaryotic and eukaryotic cells

# data[].attributes.headline
Advisement - Club Day - e-Learning Bell Schedule

# data[].attributes.subject
Advisement - Club Day - e-Learning Bell Schedule

# data[].attributes.attachment_link.title
Advisement - Club Day - e-Learning Bell Schedule

# data[].attributes.body
https://commons.wikimedia.org/wiki/File:Characteristics_of_life.svg

# data[].attributes.body
Video (7:42)

# data[].attributes.attachment_link.title
STEM Academy Student Handbook 2020-2021 (1)

# data[].attributes.attachment_link.readable_text
Identify the different kinds of cells that make up different kinds of organisms

There are two types of cells: prokaryotic and eukaryotic. In this section, we'll explore the similarities and differences between these two types.

LEARNING OBJECTIVES

Identify features common to all cells

Contrast the composition and size of prokaryotic and eukaryotic cells

Cells fall into one of two broad categories: prokaryotic and eukaryotic. The single-celled organisms of the domains Bacteria and Archaea are classified as prokaryotes ( pro = before; karyon- = nucleus). Animal cells, plant cells, fungi, and protists are eukaryotes ( eu = true).

Components of Prokaryotic Cells

All cells share four common components: (1) a plasma membrane, an outer covering that separates the cell's interior from its surrounding environment; (2) cytoplasm, consisting of a jelly-like region within the cell in which other cellular components are found; (3) DNA, the genetic material of the cell; and (4) ribosomes, particles that synthesize proteins. However, prokaryotes differ from eukaryotic cells in several ways.

A prokaryotic cell is a simple, single-celled (unicellular) organism that lacks a nucleus, or any other membrane-bound organelle. We will shortly come to see that this is significantly different in eukaryotes. Prokaryotic DNA is found in the central part of the cell: a darkened region called the nucleoid (Figure 1).

Unlike Archaea and eukaryotes, bacteria have a cell wall made of peptidoglycan, comprised of sugars and amino acids, and many have a polysaccharide capsule (Figure 1). The cell wall acts as an extra layer of protection, helps the cell maintain its shape, and prevents dehydration. The capsule enables the cell to attach to surfaces in its environment. Some prokaryotes have flagella, pili, or fimbriae. Flagella are used for locomotion, while most pili are used to exchange genetic material during a type of reproduction called conjugation.

Eukaryotic Cells

In nature, the relationship between form and function is apparent at all levels, including the level of the cell, and this will become clear as we explore eukaryotic cells. The principle "form follows function" is found in many contexts. It means that, in general, one can deduce the function of a structure by looking at its form, because the two are matched. For example, birds and fish have streamlined bodies that allow them to move quickly through the medium in which they live, be it air or water.

A eukaryotic cell is a cell that has a membrane-bound nucleus and other membrane-bound compartments or sacs, called organelles, which have specialized functions. The word eukaryotic means "true kernel" or "true nucleus," alluding to the presence of the membrane-bound nucleus in these cells. The word "organelle" means "little organ," and, as we learned earlier, organelles have specialized cellular functions, just as the organs of your body have specialized functions.

Cell Size

At 0.1-5.0 µm in diameter, prokaryotic cells are significantly smaller than eukaryotic cells, which have diameters ranging from 10-100 µm (Figure 2). The small size of prokaryotes allows ions and organic molecules that enter them to quickly spread to other parts of the cell. Similarly, any wastes produced within a prokaryotic cell can quickly move out. However, larger eukaryotic cells have evolved different structural adaptations to enhance cellular transport. Indeed, the large size of these cells would not be possible without these adaptations. In general, cell size is limited because volume increases much more quickly than does cell surface area. As a cell becomes larger, it becomes more and more difficult for the cell to acquire sufficient materials to support the processes inside the cell, because the relative size of the surface area across which materials must be transported declines.

IN SUMMARY: COMPARING PROKARYOTIC AND EUKARYOTIC CELLS

Prokaryotes are single-celled organisms of the domains Bacteria and Archaea. All prokaryotes have plasma membranes, cytoplasm, ribosomes, a cell wall, DNA, and lack membrane-bound organelles. Many also have polysaccharide capsules. Prokaryotic cells range in diameter from 0.1-5.0 µm.

Like a prokaryotic cell, a eukaryotic cell has a plasma membrane, cytoplasm, and ribosomes, but a eukaryotic cell is typically larger than a prokaryotic cell, has a true nucleus (meaning its DNA is surrounded by a membrane), and has other membrane-bound organelles that allow for compartmentalization of functions. Eukaryotic cells tend to be 10 to 100 times the size of prokaryotic cells.

Check Your Understanding

Answer the question(s) below to see how well you understand the topics covered in the previous section. This short quiz does not count toward your grade in the class, and you can retake it an unlimited number of times.

Use this quiz to check your understanding and decide whether to (1) study the previous section further or (2) move on to the next section.

# data[].attributes.attachment_link.description
There are two types of cells: prokaryotic and eukaryotic. In this section, we'll explore the similarities and differences between these two types. Identify features common to all cells Contrast the composition and size of prokaryotic and eukaryotic cells Cells fall into one of two broad categories: prokaryotic and eukaryotic.

# data[].attributes.attachment_link.description
Create a new spreadsheet and edit with others at the same time -- from your computer, phone or tablet. Get stuff done with or without an internet connection. Use Sheets to edit Excel files. Free from Google.

# data[].attributes.attachment_link.description
This video introduces biology and the characteristics that make something living. It is made for my 9th and 10th grade high school biology students.

# data[].attributes.body
Video (3:44)

# data[].attributes.attachment_link.readable_text
List the defining characteristics of biological life

Biology is the science that studies life, but what exactly is life? This may sound like a silly question with an obvious response, but it is not always easy to define life. For example, a branch of biology called virology studies viruses, which exhibit some of the characteristics of living entities but lack others. It turns out that although viruses can attack living organisms, cause diseases, and even reproduce, they do not meet the criteria that biologists use to define life. Consequently, virologists are not biologists, strictly speaking. Similarly, some biologists study the early molecular evolution that gave rise to life; since the events that preceded life are not biological events, these scientists are also excluded from biology in the strict sense of the term.

From its earliest beginnings, biology has wrestled with these questions: What are the shared properties that make something "alive"? And once we know something is alive, how do we find meaningful levels of organization in its structure?

Learning Objectives

List the properties of life

Order the levels of organization of living things

Properties of Life

All living organisms share several key characteristics or functions: order, sensitivity or response to the environment, reproduction, growth and development, regulation, homeostasis, and energy processing. When viewed together, these characteristics serve to define life.

Order

Organisms are highly organized, coordinated structures that consist of one or more cells. Even very simple, single-celled organisms are remarkably complex: inside each cell, atoms make up molecules; these in turn make up cell organelles and other cellular inclusions.

In multicellular organisms (Figure 1), similar cells form tissues. Tissues, in turn, collaborate to create organs (body structures with a distinct function). Organs work together to form organ systems.

Sensitivity or Response to Stimuli

Organisms respond to diverse stimuli. For example, plants can bend toward a source of light, climb on fences and walls, or respond to touch (Figure 2).

Even tiny bacteria can move toward or away from chemicals (a process called chemotaxis) or light ( phototaxis). Movement toward a stimulus is considered a positive response, while movement away from a stimulus is considered a negative response.

Watch this video to see how plants respond to a stimulus-from opening to light, to wrapping a tendril around a branch, to capturing prey.

Reproduction

Single-celled organisms reproduce by first duplicating their DNA, and then dividing it equally as the cell prepares to divide to form two new cells. Multicellular organisms often produce specialized reproductive germline cells that will form new individuals. When reproduction occurs, genes containing DNA are passed along to an organism's offspring. These genes ensure that the offspring will belong to the same species and will have similar characteristics, such as size and shape.

Growth and Development

Organisms grow and develop following specific instructions coded for by their genes. These genes provide instructions that will direct cellular growth and development, ensuring that a species' young (Figure 3) will grow up to exhibit many of the same characteristics as its parents.

Regulation

Even the smallest organisms are complex and require multiple regulatory mechanisms to coordinate internal functions, respond to stimuli, and cope with environmental stresses. Two examples of internal functions regulated in an organism are nutrient transport and blood flow. Organs (groups of tissues working together) perform specific functions, such as carrying oxygen throughout the body, removing wastes, delivering nutrients to every cell, and cooling the body.

Homeostasis

In order to function properly, cells need to have appropriate conditions such as proper temperature, pH, and appropriate concentration of diverse chemicals. These conditions may, however, change from one moment to the next. Organisms are able to maintain internal conditions within a narrow range almost constantly, despite environmental changes, through homeostasis (literally, "steady state")-the ability of an organism to maintain constant internal conditions. For example, an organism needs to regulate body temperature through a process known as thermoregulation. Organisms that live in cold climates, such as the polar bear (Figure 4), have body structures that help them withstand low temperatures and conserve body heat. Structures that aid in this type of insulation include fur, feathers, blubber, and fat. In hot climates, organisms have methods (such as perspiration in humans or panting in dogs) that help them to shed excess body heat.

Energy Processing

All organisms use a source of energy for their metabolic activities. Some organisms capture energy from the sun and convert it into chemical energy in food (photosynthesis); others use chemical energy in molecules they take in as food (cellular respiration).

Levels of Organization of Living Things

Living things are highly organized and structured, following a hierarchy that can be examined on a scale from small to large. The atom is the smallest and most fundamental unit of matter. It consists of a nucleus surrounded by electrons. Atoms form molecules. A molecule is a chemical structure consisting of at least two atoms held together by one or more chemical bonds. Many molecules that are biologically important are macromolecules, large molecules that are typically formed by polymerization (a polymer is a large molecule that is made by combining smaller units called monomers, which are simpler than macromolecules). An example of a macromolecule is deoxyribonucleic acid (DNA) (Figure 6), which contains the instructions for the structure and functioning of all living organisms.

Some cells contain aggregates of macromolecules surrounded by membranes; these are called organelles. Organelles are small structures that exist within cells. Examples of organelles include mitochondria and chloroplasts, which carry out indispensable functions: mitochondria produce energy to power the cell, while chloroplasts enable green plants to utilize the energy in sunlight to make sugars. All living things are made of cells; the cell itself is the smallest fundamental unit of structure and function in living organisms. (This requirement is why viruses are not considered living: they are not made of cells. To make new viruses, they have to invade and hijack the reproductive mechanism of a living cell; only then can they obtain the materials they need to reproduce.) Some organisms consist of a single cell and others are multicellular. Cells are classified as prokaryotic or eukaryotic. Prokaryotes are single-celled or colonial organisms that do not have membrane-bound nuclei or organelles; in contrast, the cells of eukaryotes do have membrane-bound organelles and a membrane-bound nucleus.

In larger organisms, cells combine to make tissues, which are groups of similar cells carrying out similar or related functions. Organs are collections of tissues grouped together performing a common function. Organs are present not only in animals but also in plants. An organ system is a higher level of organization that consists of functionally related organs. Mammals have many organ systems. For instance, the circulatory system transports blood through the body and to and from the lungs; it includes organs such as the heart and blood vessels. Organisms are individual living entities. For example, each tree in a forest is an organism. Single-celled prokaryotes and single-celled eukaryotes are also considered organisms and are typically referred to as microorganisms.

All the individuals of a species living within a specific area are collectively called a population. For example, a forest may include many pine trees. All of these pine trees represent the population of pine trees in this forest. Different populations may live in the same specific area. For example, the forest with the pine trees includes populations of flowering plants and also insects and microbial populations. A community is the sum of populations inhabiting a particular area. For instance, all of the trees, flowers, insects, and other populations in a forest form the forest's community. The forest itself is an ecosystem. An ecosystem consists of all the living things in a particular area together with the abiotic, non-living parts of that environment such as nitrogen in the soil or rain water. At the highest level of organization (Figure 7), the biosphere is the collection of all ecosystems, and it represents the zones of life on earth. It includes land, water, and even the atmosphere to a certain extent.

Practice Question

From a single organelle to the entire biosphere, living organisms are parts of a highly structured hierarchy.

Which of the following statements is false?

1. Tissues exist within organs, which exist within organ systems.

2. Communities exist within populations, which exist within ecosystems.

3. Organelles exist within cells, which exist within tissues.

4. Communities exist within ecosystems, which exist in the biosphere.

Check Your Understanding

Answer the question(s) below to see how well you understand the topics covered in the previous section. This short quiz does not count toward your grade in the class, and you can retake it an unlimited number of times.

Use this quiz to check your understanding and decide whether to (1) study the previous section further or (2) move on to the next section.

# data[].attributes.attachment_link.description
Biology is the science that studies life, but what exactly is life? This may sound like a silly question with an obvious response, but it is not always easy to define life. For example, a branch of biology called virology studies viruses, which exhibit some of the characteristics of living entities but lack others.

# data[].attributes.body
Video (3:33)

# data[].attributes.attachment_link.title
Characteristics of Living Things-What makes something alive?

# data[].attributes.attachment_link.description
Covers seven characteristics shared by all living organisms.

# data[].attributes.body
Video: Starting at 2:25

# data[].attributes.attachment_link.title
What is Biology? The Characteristics of Life.

# data[].attributes.attachment_link.description
This is the first video tutorial in the Biology Series. This video introduces biology and explains what it means to be alive. Thanks for watching. Please ‘like’ and ‘subscribe’ Learn more science at www.thescienceclassroom.org #biology

# data[].attributes.body
bioexplorer.net

# data[].attributes.attachment_link.readable_text
Cellular Organization: Life exhibits a wide variety of levels of organization. For one, the cell is considered the smallest living functional unit of an entity and is always known as the basic unit of life. Despite their minute size, cells are still organized in a precise manner.

What is Cellular Organization?

By definition, cellular organization is the components that make up the cell and how they are arranged inside it. Each component called an organelle, performs a specific function vital for the cell. This page will explore the basic functional components of the cell and cell shape and its size. Let's take a closer look.

Functional Components Of The Cell

1. Nucleus

2. Cell Membrane (also Plasma Membrane)

3. Cytoplasm

By definition, the cytoplasm is the fluid that fills the cell up and is surrounded by the cell membrane. The cytoplasm is mainly composed of salts and proteins dissolved in water.

In eukaryotes, the cytoplasm is consisted of all materials (i.e. organelles) located in within the cell, excluding the nucleus.

The part of the cytoplasm that does not contain any organelles is referred to as the cytosol.

4. Cell Wall

5. Mitochondrion

6. Chloroplast

7. Rough Endoplasmic Reticulum

8. Smooth Endoplasmic Reticulum

9. Ribosome

Ribosome are the sites where protein synthesis occurs. These proteins are important as they serve a variety of purposes like catalyze biochemical reactions, act as structural support, and building blocks of some membranes.

Ribosomes are found in both prokaryotic and eukaryotic organisms.

Inside the cell, the ribosomes are either found to be suspended in the cytoplasm or attached to the rough ER.

10. Golgi Body

11. Vesicle

12. Vacuole

13. Lysosome

14. Centrioles

Cell Shape And Size

Different cells have different shapes and their unique morphologies are directly related to their function:

Plant cells, in general, have rectangular, rigid walls, and distinct edges. Such structure is contributed by the presence of cell wall that forces the cell to have a definite shape.

Unlike plant cells, animal cells tend to have more irregular body shapes due to the absence of cell wall in their overall structure.

Microorganisms like bacteria have three types of cell shape: oval (cocci), rod-shaped (bacilli), spiral, star-shaped, and rectangular.

See the differences between plant and animal cells here.

Like shapes, the size of cells is also linked to their functions. Depending on the type of organism, the size of the cell greatly varies.

In particular, egg cells are the largest cells that an organism has. This is very much related to their function as the development of the zygote after fertilization requires huge amounts of energy. Approximately, the human egg cell measures 0.12 mm in diameter.

On the other hand, the smallest cell is that of the parasitic bacterium Mycoplasma gallicepticum. This bacterium, which thrives in the bladder, respiratory and reproductive tracts of mammals. This cell has an average diameter of 0.0001 mm.

To perform more efficiently, cells usually undergo a so-called multi-cellular organization where similar cells group together to form tissues. A group of tissues and similar structures which perform similar functions together constitute an organ. A group of organs performing physiological processes form an organ system and organ systems that work together constitute an organism.

Isn't it amazing how a single cell can be so complex?

Cite This Page

[1] - Cooper, Geoffrey M. "The Nucleus." The Cell: A Molecular Approach. 2nd edition. January 01, 1970. Accessed January 06, 2017. Link.

[2] - Cooper, Geoffrey M. "Structure of the Plasma Membrane." The Cell: A Molecular Approach. 2nd edition. January 01, 1970. Accessed January 06, 2017. Link.

[3] - Wilkin, Ph.D. Douglas, and Ph.D. Jean Brainard. "Phospholipid Bilayers." CK-12 Foundation. November 21, 2016. Accessed January 06, 2017. Link.

[4] - Nature.com. Accessed January 06, 2017. Link.

[5] - ScienceDaily. Accessed January 06, 2017. Link.

[6] - "Endoplasmic Reticulum (Rough and Smooth)." British Society for Cell Biology. Accessed January 06, 2017. Link.

[7] - Wada, Yoh. "Vacuoles in mammals: A subcellular structure indispensable for early embryogenesis." Bioarchitecture. January 01, 2013. Accessed January 06, 2017. Link.

[8] - Cooper, Geoffrey M. "Lysosomes." The Cell: A Molecular Approach. 2nd edition. January 01, 1970. Accessed January 06, 2017. Link.

[9] - "CELLS II: CELLULAR ORGANIZATION." CELLS II: CELLULAR ORGANIZATION. Accessed January 06, 2017. Link.

# data[].attributes.attachment_link.title
Cellular Organization | Exploring The Cell | BioExplorer.Net

# data[].attributes.attachment_link.description
By definition, cellular organization is the components that make up the cell and how they are arranged inside it. Each component, called an organelle, performs a specific function that is vital for the cell. In this article, we will explore the basic functional components of the cell and cell shape and its size.

# data[].attributes.attachment_link.title
Metabolism | Definition, Process, & Biology

# data[].attributes.attachment_link.description
metabolism, the sum of the chemical reactions that take place within each cell of a living organism and that provide energy for vital processes and for synthesizing new organic material. Living organisms are unique in that they can extract energy from their environments and use it to carry out activities such as movement, growth and development, and reproduction.

# data[].attributes.attachment_link.title
Heredity, Genes, and DNA - The Cell - NCBI Bookshelf

# data[].attributes.attachment_link.description
Perhaps the most fundamental property of all living things is the ability to reproduce. All organisms inherit the genetic information specifying their structure and function from their parents. Likewise, all cells arise from preexisting cells, so the genetic material must be replicated and passed from parent to progeny cell at each cell division. How genetic information is replicated and transmitted from cell to cell and organism to organism thus represents a question that is central to all of biology. Consequently, elucidation of the mechanisms of genetic transmission and identification of the genetic material as DNA were discoveries that formed the foundation of our current understanding of biology at the molecular level.

# data[].attributes.body
Notes from khan academy.

# data[].attributes.attachment_link.description
Create a new document and edit with others at the same time -- from your computer, phone or tablet. Get stuff done with or without an internet connection. Use Docs to edit Word files. Free from Google.