Skip to main content. Cell Structure and Function. Search for:. Comparing Prokaryotic and Eukaryotic Cells Learning Objectives By the end of this section, you will be able to: Name examples of prokaryotic and eukaryotic organisms Compare and contrast prokaryotic cells and eukaryotic cells Describe the relative sizes of different kinds of cells.
Additional Self Check Question 1. Describe the structures that are characteristic of a prokaryote cell. Answer 1. Prokaryotic cells are surrounded by a plasma membrane and have DNA, cytoplasm, and ribosomes, like eukaryotic cells. They also have cell walls and may have a cell capsule. Prokaryotes have a single large chromosome that is not surrounded by a nuclear membrane.
Prokaryotes may have flagella or motility, pili for conjugation, and fimbriae for adhesion to surfaces. Muscle cells are slender fibers that bundle together for muscle contraction. The cells of multicellular organisms may also look different according to the organelles needed inside of the cell. For example, muscle cells have more mitochondria than most other cells so that they can readily produce energy for movement; cells of the pancreas need to produce many proteins and have more ribosomes and rough endoplasmic reticula to meet this demand.
Although all cells have organelles in common, the number and types of organelles present reveal how the cell functions. The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. The Rights Holder for media is the person or group credited.
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This "forgotten" branch of the eukaryote family tree is the kingdom Protista , made up of protists. This category of organisms is diverse, yet at the same time characterized by a lack of specialized tissues. Cells are the smallest irreducible structures that, by themselves, retain all of the properties of life. These properties include metabolism, which cells demonstrate in abundance in both the "building up" and "breaking down" directions, organization and structure and a means of reproducing.
All cells have a cell membrane forming the external boundary, cytoplasm forming most of the "gelatinous" interior, genetic material in the form of DNA deoxyribonucleic acid and ribosomes , which make proteins. Eukaryotic cells, which are descended from prokaryotic cells in a relationship going back several billion years, also have a smattering of other specialized components, called organelles. In eukaryotes such as protists, some cells in glands called gonads are set aside to divide into gametes , or sex cells.
This happens in a process called meiosis. The overwhelming majority of cells in your body, however, form and divide via a process called mitosis , a form of asexual reproduction akin to basic duplication. To learn more about subscribing to AccessScience, or to request a no-risk trial of this award-winning scientific reference for your institution, fill in your information and a member of our Sales Team will contact you as soon as possible.
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Contributors include more than 10, highly qualified scientists and 46 Nobel Prize winners. Cell biology Article by: Goodman, Steven R. Key Concepts Hide A cell is the microscopic functional and structural unit of all living organisms.
Eukaryotic cells have a nucleus and multiple, compartmentalized molecules of linear DNA. Prokaryotic cells lack a nucleus, have a single circular molecule of DNA, and are relatively smaller. In addition to a nucleus, the organelles of eukaryotic cells include the plasma membrane, cytoskeleton, endoplasmic reticulum, Golgi apparatus, lysosomes, mitochondria, and peroxisomes.
Many, but not all, plant cells contain characteristic features found only in plants, including a rigid outer cell wall, internal vacuoles for storage, and chloroplasts for energy production. Prokaryotic bacterial cells All eubacteria have an inner plasma membrane that serves as a semipermeable barrier Fig. See also: Cell membranes Eubacteria can be further separated into two classes based on their ability to retain the dye crystal violet.
Eukaryotic cells In a light microscopic view of a eukaryotic cell, a plasma membrane can be seen that defines the outer boundaries of the cell, surrounding the cell's protoplasm or contents.
See also: Cell organization ; Cytoplasm Fig. A term with an asterisk indicates that the structure is not found in plant cells. Plasma membrane The plasma membrane serves as a selective permeability barrier between a cell's environment and its cytoplasm. Cytoskeleton The cytoskeleton is involved in establishing cell shape, polarity, and motility, as well as in directing the movement of organelles within the cell.
Nucleus One of the most prominent organelles within a eukaryotic cell is the nucleus. Endoplasmic reticulum The endoplasmic reticulum is composed of membrane-enclosed flattened sacs or cisternae. Golgi apparatus The final modifications of proteins and glycolipids occur within a series of flattened membranous sacs comprising the Golgi apparatus.
Lysosome The lysosome is a membrane-bound organelle with a luminal pH of 5. Mitochondrion The mitochondrion contains a double membrane: the outer membrane, which contains a channel-forming protein named porin; and an inner membrane, which contains multiple infolds called cristae. Peroxisome Within the peroxisome, hydrogen atoms are removed from organic substrates, and hydrogen peroxide is formed. Additional features of plant cells Plant cells are distinguished from other eukaryotic cells by various features Fig.
A term with an asterisk indicates that the structure is not found in animal cells. Test Your Understanding Hide Compare and contrast the two types of biological cells. What other eukaryotic cellular structure is similar to a plant's chloroplast in structure and function? Critical Thinking: Why would it be disadvantageous for multicellular organisms to consist of prokaryotic cells?
Critical Thinking: Would you expect cells in different organs in complex animals to have the same structure? Why or why not? Critical Thinking: What advantage does the cytoskeleton give to large eukaryotic cells? You may already have access to this content. Sign In.
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