All You Need To Know About animal cell

animal cell

Animal cells are eukaryotic cells or cells with a membrane-bound nucleus.

Unlike prokaryotic cells, DNA in animal cells is housed within the nucleus. In addition to having a nucleus, animal cells also contain other membrane-bound organelles, or tiny cellular structures, that carry out specific functions necessary for normal cellular operation. Organelles have a wide range of responsibilities that include everything from producing hormones and enzymes to providing energy for animal cells.

Key Takeaways
Animal cells are eukaryotic cells that have both a membrane-bound nucleus and other membrane-bound organelles. These organelles carry out specific functions that are needed for the normal functioning of the cell.

Plant and animal cells are similar in that they are both eukaryotic and have similar types of organelles. Plant cells tend to have more uniform sizes than animal cells.
Cell structure and organelle examples include: centrioles, the Golgi complex, microtubules, nucleopores, peroxisomes, and ribosomes.
Animals typically contain trillions of cells. Humans, for example, also have hundreds of different cell types. The shape, size and structure of cells go along with their specific function.

Animal Cells vs. Plant Cells

animal cell

Animal cells and plant cells are similar in that they are both eukaryotic cells and have similar organelles. Animal cells are generally smaller than plant cells. While animal cells come in various sizes and tend to have irregular shapes, plant cells are more similar in size and are typically rectangular or cube shaped. A plant cell also contains structures not found in an animal cell. Some of these include a cell wall, a large vacuole, and plastids. Plastids, such as chloroplasts, assist in storing and harvesting needed substances for the plant. Animal cells also contain structures such as centrioles, lysosomes, cilia, and flagella that are not typically found in plant cells.


Organelles and Components of Animal Cells

animal cell

The following are examples of structures and organelles that can be found in typical animal cells:

Cell (Plasma) Membrane - thin, semi-permeable membrane that surrounds the cytoplasm of a cell, enclosing its contents.

Centrioles - cylindrical structures that organize the assembly of microtubules during cell division.
Cilia and flagella - specialized groupings of microtubules that protrude from some cells and aid in cellular locomotion.

Cytoplasm - gel-like substance within the cell.
Cytoskeleton - a network of fibers throughout the cell's cytoplasm that gives the cell support and helps to maintain its shape.

Endoplasmic Reticulum - an extensive network of membranes composed of both regions with ribosomes (rough ER) and regions without ribosomes (smooth ER).
Golgi Complex - also called the Golgi apparatus, this structure is responsible for manufacturing, storing and shipping certain cellular products.

Lysosomes - sacs of enzymes that digest cellular macromolecules such as nucleic acids.
Microtubules - hollow rods that function primarily to help support and shape the cell.
Mitochondria - cell components that generate energy for the cell and are the sites of cellular respiration.
Nucleus - membrane-bound structure that contains the cell's hereditary information.
Nucleolus - structure within the nucleus that helps in the synthesis of ribosomes.
Nucleopore - a tiny hole in the nuclear membrane that allows nucleic acids and proteins to move into and out of the nucleus.
Peroxisomes - enzyme containing structures that help to detoxify alcohol, form bile acid, and break down fats.
Ribosomes - consisting of RNA and proteins, ribosomes are responsible for protein assembly.

                                                       Animal Cell Types

animal cell

In the hierarchical structure of life, cells are the simplest living units. Animal organisms can be composed of trillions of cells. In the human body, there are hundreds of different types of cells. These cells come in all shapes and sizes and their structure suits their function. For example, the body's nerve cells or neurons have a vastly different shape and function than red blood cells. Nerve cells transport electrical signals throughout the nervous system. They are elongated and thin, with projections that extend out to communicate with other nerve cells in order to conduct and transmit nerve impulses. The major role of red blood cells is to transport oxygen to body cells. Their small, flexible disc shape enables them to maneuver through tiny blood vessels to deliver oxygen to organs and tissues.

Animal Cell Definition

Animal cells are the basic unit of life in organisms of the kingdom Animalia. They are eukaryotic cells, meaning that they have a true nucleus and specialized structures called organelles that carry out different functions. Animal cells do not have cell walls or chloroplasts, the organelle that carries out photosynthesis.

Animal Cell Overview

Animals, plants, fungi, and protists all have eukaryotic cells, while bacteria and archaea have simpler prokaryotic cells. Eukaryotic cells are distinguished by the presence of a nucleus and other membrane-bound organelles. Animal cells,

unlike plants and fungi cells, do not have a cell wall. Instead, multicellular animals have a skeleton which provides support for their tissues and organs.

Likewise, animal cells also lack the chloroplasts found in plants, which is used to produce sugars via photosynthesis.

As such, animal cells are considered heterotrophic, as opposed to autotrophic plant cells. This means that animal cells must obtain nutrients from other sources, by eating plant cells or other animal cells. However, like all eukaryotic cells, animal cells have mitochondria. These organelles are used to create ATP from various sources of energy including carbohydrates, fats, and proteins. Besides mitochondria, many other organelles are found within animal cells which help them carry out the many functions required for life.

Animal Cell Structure

The cell has a variety of different parts. It contains many different types of specialized organelles that carry out all of its functions. Not every animal cell has all types of organelles, but in general, animal cells do contain most if not all of the following organelles.

Animal cell structure

This is an artist’s rendering of the parts of an animal cell.

Nucleus

The nucleus contains a cell’s deoxyribonucleic acid (DNA), its genetic material. DNA contains instructions for making proteins, which controls all of the body’s activities. In the nucleus, DNA is tightly winded around histones,

which are proteins, to form structures called chromosomes. The nucleus regulates which genes are expressed in the cell, which controls the cell’s activity and functioning and will be different depending on the type of cell. DNA is located in the nucleolus region of the nucleus, where ribosomes are made. The nucleus is surrounded by a nuclear envelope (also called nuclear membrane), which separates it from the rest of the cell.

The nucleus also regulates the growth and division of the cell. When the cell is preparing to divide during mitosis, the chromosomes in the nucleus duplicate and separate, and two daughter cells are formed. Organelles called centrosomes help organize DNA during cell division. Cells usually have one nucleus each.

Ribosomes

Ribosomes are where proteins are synthesized. They are found within all cells, including animal cells. In the nucleus, a sequence of DNA that codes for a specific protein is copied onto a complementary messenger RNA (mRNA) chain. The mRNA

chain travels to the ribosome via transfer RNA (tRNA), and its sequence is used to determine the correct placement of amino acids in a chain that makes up the protein. In animal cells, ribosomes can be found freely in a cell’s cytoplasm, or attached to membranes of the endoplasmic reticulum.

Endoplasmic Reticulum

The endoplasmic reticulum (ER) is a network of membranous sacs called cisternae that branches off from the outer nuclear membrane.

It modifies and transports proteins that are made by ribosomes. There are two kinds of endoplasmic reticulum, smooth and rough. Rough ER has ribosomes attached. Smooth ER does not have ribosomes attached and has functions in making lipids and steroid hormones and removing toxic substances.

Vesicles

Vesicles are small spheres of a lipid bilayer, which also makes up the cell’s outer membrane. They are used for transporting molecules throughout the cell from one organelle to another and are also involved in metabolism. Specialized vesicles called lysosomes contain enzymes that digest large molecules like carbohydrates, lipids, and proteins into smaller ones so that they can be used by the cell.

Golgi Apparatus

The Golgi apparatus, also called the Golgi complex or Golgi body, is also made up of cisternae, but the cisternae are not interconnected like those of the ER. The Golgi apparatus receives proteins from the ER and folds, sorts, and packages these proteins into vesicles.

Mitochondria

The process of cellular respiration occurs in the mitochondria. During this process, sugars and fats are broken down and energy is released in the form of adenosine triphosphate (ATP). ATP powers all cellular processes, and mitochondria produce a cell’s ATP, so mitochondria are commonly known as “the powerhouse of the cell”.

Cytosol

The cytosol is the liquid contained within cells. Cytosol and all the organelles within it, except for the nucleus, are collectively referred to as a cell’s cytoplasm. This solution is mostly made of water, but also contains ions like potassium, proteins, and small molecules. The pH is generally neutral, around 7.

Cytoskeleton

The cytoskeleton is a network of filaments and tubules found throughout the cytoplasm of the cell. It has many functions: it gives the cell shape, provides strength, stabilizes tissues, anchors organelles within the cell, and has a role in cell signaling. There are three types of cytoskeletal filaments: microfilaments, microtubules, and intermediate filaments. Microfilaments are the smallest, while microtubules are the biggest.

Cell Membrane

The cell membrane surrounds the entire cell. Animal cells only have a cell membrane; they do not have a cell wall as plant cells do. The cell membrane is a double layer made up of phospholipids. Phospholipids are molecules with a phosphate group head attached to glycerol and two fatty acid tails. They spontaneously form double membranes in water due to the hydrophilic properties of the head and hydrophobic properties of the tails.

The cell membrane is selectively permeable, meaning it only allows certain molecules through. Oxygen and carbon dioxide pass through easily, while larger or charged molecules must go through a special channel in the membrane. This maintains homeostasis within the cell.

Animal Cells Function

Cells carry out all the processes of the body including producing and storing energy, making proteins, replicating the DNA, and transportation of molecules through the body. Cells are highly specialized to carry out specific tasks. For example, the heart has cardiac muscle cells that beat in unison. Digestive tract cells have cilia, which are finger-like projections that increase surface area for the absorption of nutrients during digestion. Each cell type has the organelles suited to its particular task.

There are over 200 different types of cells in the human body. Red blood cells contain hemoglobin, the molecule that carries oxygen, and they have no nuclei; this is a specialization that allows each red blood cell to carry as much oxygen within it as possible.

Multiple cells form tissues. These groups of cells carry out a specific function. In turn, groups of similar tissues form the body’s organs, such as the brain, lungs, and heart. Organs work together in organ systems, like the nervous system, digestive system, and circulatory system. Organ systems vary depending on the species.

For example, insects have open circulatory systems, where blood is pumped directly into body cavities and surrounds their tissues. Vertebrates such as fish, mammals, and birds, on the other hand, have closed circulatory systems. Their blood is enclosed within blood vessels where it travels to target tissues. In this way, all animal have evolved specific uses for each of the cells in their bodies.