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Study cells and their function, systems, structure and interaction with other living organisms

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Performs lab tests and analyses, can work in different fields such as medicine, biology, environment and electronics

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Responsible for writing grant proposals, and to conduct research and report on their findings

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Nucleus - Monitors the main functions of the cell
Cell wall - Surrounds the cell and protects it
Vacuole - Vacuoles help with functions such as storage, ingestion, and digestion
Cell membrane
Chloroplasts
Ribsome
Mitochondria
Typically have distinct edges on the shape of the cell, and can be rectangular

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Nucleus Monitors the main functions of the cell
Cell membrane -
Mitochondria
Ribosomes
Cilia
Endoplasmic reticulum
Mostly round in shape, irregular, and do not have a distinct shape

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Job Overview

Here at Acme Corp, we are the leading company in our industry in the Springfield metro area. We're proud of our 3.9 Glassdoor rating. We are looking to hire a talented Lab Technician to join our team. If you're a passionate self-starter, Acme Corp is a perfect place to grow your career. This is the opportunity you've been looking for.

Responsibilities for Lab Technician

Perform routine and non-routine tests and analyses using the appropriate technical equipment and instruments

Receive or collect, as well as process, samples

Calculate test results, and log and report results using a computer

Prepare and supervise experiments

Perform quality control and calibrate equipment if necessary

Maintain equipment in proper working order and maintain a clean work area

Practice safe work habits, including complying with all safety, health, and environmental rules and regulations

Qualifications for Lab Technician

High school diploma or general education degree (GED) required, associate's or Bachelor's degree in a scientific field preferred

1-2 years of experience working in a lab

Computer skills: knowledge of Microsoft Office and other relevant computer programs

Analytical and numerical skills: ability to perform mathematical calculations (add, subtract, multiply, divide) in different units of measurement; ability to use concepts such as fractions, percentages, and ratios

Strong attention to detail

Ability to write correspondence and reports

Excellent organizational skills

Ability to perform physically demanding work such as moving and lifting equipment, standing for long periods of time, etc.

Ready to Hire a Lab Technician?
Try Job Postings

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Here at Acme Corp, we are the leading company in our industry in the Springfield metro area. We're proud of our 3.9 Glassdoor rating. We are looking to hire a talented Lab Technician to join our team. If you're a passionate self-starter, Acme Corp is a perfect place to grow your career.

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Table of Contents

cell wall, specialized form of extracellular matrix that surrounds every cell of a plant. The cell wall is responsible for many of the characteristics that distinguish plant cells from animal cells. Although often perceived as an inactive product serving mainly mechanical and structural purposes, the cell wall actually has a multitude of functions upon which plant life depends. Such functions include: (1) providing the living cell with mechanical protection and a chemically buffered environment, (2) providing a porous medium for the circulation and distribution of water, minerals, and other small nutrient molecules, (3) providing rigid building blocks from which stable structures of higher order, such as leaves and stems, can be produced, and (4) providing a storage site of regulatory molecules that sense the presence of pathogenic microbes and control the development of tissues.

Certain prokaryotes, algae, slime molds, water molds, and fungi also have cell walls. Bacterial cell walls are characterized by the presence of peptidoglycan, whereas those of Archaea characteristically lack this chemical. Algal cell walls are similar to those of plants, and many contain specific polysaccharides that are useful for taxonomy. Unlike those of plants and algae, fungal cell walls lack cellulose entirely and contain chitin. The scope of this article is limited to plant cell walls.

Mechanical properties

All cell walls contain two layers, the middle lamella and the primary cell wall, and many cells produce an additional layer, called the secondary wall. The middle lamella serves as a cementing layer between the primary walls of adjacent cells. The primary wall is the cellulose-containing layer laid down by cells that are dividing and growing. To allow for cell wall expansion during growth, primary walls are thinner and less rigid than those of cells that have stopped growing. A fully grown plant cell may retain its primary cell wall (sometimes thickening it), or it may deposit an additional, rigidifying layer of different composition, which is the secondary cell wall. Secondary cell walls are responsible for most of the plant's mechanical support as well as the mechanical properties prized in wood. In contrast to the permanent stiffness and load-bearing capacity of thick secondary walls, the thin primary walls are capable of serving a structural, supportive role only when the vacuoles within the cell are filled with water to the point that they exert a turgor pressure against the cell wall. Turgor-induced stiffening of primary walls is analogous to the stiffening of the sides of a pneumatic tire by air pressure. The wilting of flowers and leaves is caused by a loss of turgor pressure, which results in turn from the loss of water from the plant cells.

Components

Although primary and secondary wall layers differ in detailed chemical composition and structural organization, their basic architecture is the same, consisting of cellulose fibres of great tensile strength embedded in a water-saturated matrix of polysaccharides and structural glycoproteins.

Cellulose consists of several thousand glucose molecules linked end to end. The chemical links between the individual glucose subunits give each cellulose molecule a flat ribbonlike structure that allows adjacent molecules to band laterally together into microfibrils with lengths ranging from two to seven micrometres. Cellulose fibrils are synthesized by enzymes floating in the cell membrane and are arranged in a rosette configuration. Each rosette appears capable of "spinning" a microfibril into the cell wall. During this process, as new glucose subunits are added to the growing end of the fibril, the rosette is pushed around the cell on the surface of the cell membrane, and its cellulose fibril becomes wrapped around the protoplast. Thus, each plant cell can be viewed as making its own cellulose fibril cocoon.

Matrix polysaccharides

The two major classes of cell wall matrix polysaccharides are the hemicelluloses and the pectic polysaccharides, or pectins. Both are synthesized in the Golgi apparatus, brought to the cell surface in small vesicles, and secreted into the cell wall.

Hemicelluloses consist of glucose molecules arranged end to end as in cellulose, with short side chains of xylose and other uncharged sugars attached to one side of the ribbon. The other side of the ribbon binds tightly to the surface of cellulose fibrils, thereby coating the microfibrils with hemicellulose and preventing them from adhering together in an uncontrolled manner. Hemicellulose molecules have been shown to regulate the rate at which primary cell walls expand during growth.

The heterogeneous, branched, and highly hydrated pectic polysaccharides differ from hemicelluloses in important respects. Most notably, they are negatively charged because of galacturonic acid residues, which, together with rhamnose sugar molecules, form the linear backbone of all pectic polysaccharides. The backbone contains stretches of pure galacturonic acid residues interrupted by segments in which galacturonic acid and rhamnose residues alternate; attached to these latter segments are complex, branched sugar side chains. Because of their negative charge, pectic polysaccharides bind tightly to positively charged ions, or cations. In cell walls, calcium ions cross-link the stretches of pure galacturonic acid residues tightly, while leaving the rhamnose-containing segments in a more open, porous configuration. This cross-linking creates the semirigid gel properties characteristic of the cell wall matrix-a process exploited in the preparation of jellied preserves.

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cell wall | Description, Properties, Components, & Communication

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cell wall, specialized form of extracellular matrix that surrounds every cell of a plant. The cell wall is responsible for many of the characteristics that distinguish plant cells from animal cells. Although often perceived as an inactive product serving mainly mechanical and structural purposes, the cell wall actually has a multitude of functions upon which plant life depends.

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Vacuole | Definition, Structure, Function, & Facts

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Vacuole, in biology, a space within a cell that is empty of cytoplasm, lined with a membrane, and filled with fluid. Especially in protozoa, vacuoles are cytoplasmic organs, performing functions such as storage, ingestion, digestion, excretion, and expulsion of excess water.

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They have a different shape, with plant cells having a more square or rectangle shape, and animal cells having a more irregular and rounder shape. This is because plant cells have a cell wall which creates a shape of the cell, while animal cells do not have a cell wall, causing them to appear irregular.
Plant cells are larger in size than animal cells are, and have a nucleus on the side, while animal cells have a nucleus in the center.
Plant cells have one vacuole, but animal cells have many smaller vacuoles

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They are both eukaryotic cells, this is because eukaryotic cells contain a nucleus, organelles, and are enclosed by a membrane.
They have a lot of the same organelles, which include the mitochondrion, nucleus, cytoplasm, ribosomes, and an endoplasmic reticulum

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By Antonia Čirjak on June 19 2019 in Feature

A diagram showing the differences between plant and animal cells.

Around 1838, an animal physiologist, Theodor Schwann, and a botanist, Matthias Schleiden, put forth the unprecedented work on the concept of cells as the building blocks of all living organisms. From that point forward, cell theory has grown into the foundations of modern era biological research without which none of today's discoveries would be possible.

We now know that there are a myriad of different cell types, with outstanding capabilities and functions. Regardless of how different all types of cells may be, there are common characteristics to all of them, along with established differences as well.

Whether we are looking at multicellular organisms or those containing one single cell, all of them will be manifesting the same features necessary to support life. We will go over certain similarities and characteristics of the animal and plant cells, in order to gain a better understanding of each. In that context, the last few paragraphs we will be focusing on the primary differences between plant cells and animal cells.

Plant Cells

The size of plant cells usually ranges from 10-100 µm, which is a range that is bigger than animal cells. The primary function of these cells in plants is to carry out the process of photosynthesis via chloroplast which gives them their color. The cells themselves maintain their structure thanks to cellulose that make the walls of the cells. These cell walls aren't found in cells within the animal kingdom - we'll look at that in just a bit.

There are several different small structures inside the cell itself, called organelles, each with a specific function. These organelles are found in both types of cells discussed here, with many of them identical in function. Here are some of the most important ones that we find in plant cells:

Plasma Membrane - makes sure the structure of the cells remains intact and consequently keeps the cell content from spilling out. It also enables molecule movement via osmosis and diffusion.

Cell wall - different from a membrane by being found only in plant cells where it encompasses the cell membrane. The cell wall is firm but completely porous at the same time.

Chloroplasts/plastids - also found only in plant cells, these organelles enable photosynthesis when exposed to sunlight. Plastids are a group name for various kinds of chloroplasts that differ in color.

Vacuoles - provide structural integrity to the cell but also contain a variety of liquids or solids. These organelles are responsible for the colors we see on flowers.

Cytoplasm - the enzymes found within these structures are at the helm of all metabolic processes that happen inside.

Animal Cells

Animal cell size ranges from 10-30 µm, which makes it obvious that plant cells can be much bigger, clearly, depending on the plant. The primary difference from plant cells is that animal cells don't contain chloroplast nor structurally important cell walls.

It is obvious why animal cells lack in chloroplast, as there is no process of photosynthesis that generates food for the cells - animal cells create their energy via different process. But the interesting question is why exactly do they lack cell walls.

The primary theory is that the main "culprit" for the absence of cell wall is the evolution itself. Unlike plants, animal kingdom evolved to have more complex cells that are specialized to a greater extent and are able to sustain the structure of the cell without the cell wall. Obviously, just like plants cells, they also contain organelles with a variety of functions:

Plasma membrane - just like in plant cells, this structure allows for molecule movement through the cell itself and protects the internal structures of the cell, that is, other organelles.

Mitochondria - generates the energy necessary to sustain cell life by breaking down nutrients and transforming them into "food" molecules for the cell.

Cytokinesis - responsible for the division of cytoplasm while the cell is dividing. In animal cells, this division happens via the formation of cleavage furrow that grips the membrane and divides it in half.

Centrioles - cylindrically shaped objects within the cells are active during the process of cell division. Their function is to arrange the formation of microtubules - structural polymers of the cell.

Cilia - microtubules that assist in locomotion of the cell.

Main Differences Between Plant and Animal Cells

Both types of cells are identical in so much that they need to somehow produce energy to support themselves and to allow for growth. Both cell types also contain internal structures that are employed in specific processes that permit optimal functioning on a cellular level.

As was visible throughout the article, there are certain types of cells that are found in animal cells that cannot be found in plant cells, and vice versa.

Different Organelles

The most obvious ones are cell chloroplast, wall, and vacuoles. These cells can only be found in plants. Although both animal and plant kingdom falls under the eukaryotes (multi-celled, as opposed to prokaryotic, which is single-celled), animal cells have much more complex structure.

Some organelles that are found in animal cells but not in plant cells are as follows: centrioles, cilia, desmosomes and lysosomes.

Size and Structure

Animal cells look very different to plant cells. They are typically smaller than plant cells, with a roundish shape which is fairly irregular. Plant cells have a rectangular shape and are larger.

The Cell Wall

Animal cells do not contain cell walls as one of the organelles, but they do have a plasma membrane which is the same as in plants.

Nucleus Position

Both types of cells do have a nucleus, which is expected. However, in plants, it is located to the side of the cell, whereas in animal cells have their nucleus in the middle.

Number of Vacuoles

Animal cells contain a multitude of small vacuoles, while plant cells can only accommodate one, which is quite large.

Nutrient Synthesis

Animal cells are not equipped to carry out the synthesis of nutrients, while plants have no issues with synthesising various acids, vitamins and similar.

Lack of Communication Signals

Pores called plasmodesmata are in charge of communication signals, but also the passing of molecules between two cells. These pores are not identified in animal cells.

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What are the Differences Between Plant Cells and Animal Cells?

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By Antonia Čirjak on June 19 2019 in Feature Around 1838, an animal physiologist, Theodor Schwann, and a botanist, Matthias Schleiden, put forth the unprecedented work on the concept of cells as the building blocks of all living organisms. From that point forward, cell theory has grown into the foundations of modern era biological research without which none of today's discoveries would be possible.

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Eukaryotic Cell Definition

Eukaryotic cells are cells that contain a nucleus and organelles, and are enclosed by a plasma membrane. Organisms that have eukaryotic cells include protozoa, fungi, plants and animals. These organisms are grouped into the biological domain Eukaryota. Eukaryotic cells are larger and more complex than prokaryotic cells, which are found in Archaea and Bacteria, the other two domains of life.

Characteristics of Eukaryotic Cells

Eukaryotic cells contain a variety of structures called organelles, which perform various functions within the cell. Examples of organelles are ribosomes, which make proteins, the endoplasmic reticulum, which sorts and packages the proteins, and mitochondria, which produce the energy molecule adenosine triphosphate (ATP). They also have a true nucleus, which contains the genetic material DNA and is surrounded by a nuclear envelope. All of the organelles are stabilized and given physical support through the cytoskeleton, which is also involved in sending signals from one part of the cell to the other. In eukaryotic cells, the cytoskeleton is composed mainly of three types of filaments: microtubules, microfilaments, and intermediate filaments. The gel-like substance that surrounds all the organelles in the cell is called cytosol.

The figure below shows the structure of a eukaryotic cell; this is an animal cell. The nucleus and other organelles are shown. The cytosol is the blue substance surrounding all of the organelles. Together, the cytosol with all organelles besides the nucleus are grouped as cytoplasm.

Eukaryotic Cell Cycle

The cell cycle is the life cycle of a cell. During this cycle, it grows and divides. Checkpoints exist between all stages so that proteins can determine whether the cell is ready to begin the next phase of the cycle.

Quiescence (G₀)

Quiescence, also known as senescence or resting, is a phase in which the cell is not actively dividing. It is also known as Gap 0, or G ₀. This stage is considered the start of the cell cycle, although it is one that cells can reach and then stop dividing indefinitely, which ends the cell cycle. Liver, stomach, kidney cells, and neuron are all examples of cells that can reach this stage and remain in it for long periods of time. It can also occur when a cell's DNA is damaged. However, most cells do not go into the G ₀ stage at all, and can divide indefinitely throughout the life of an organism.

Interphase

In interphase, the cell grows and takes in nutrients in preparation for division. Interphase takes up about 90 percent of the cell cycle. It consists of three parts: Gap 1, Synthesis, and Gap 2.

Gap 1 (G₁) is also known as a growth phase. The cell gets larger and increases its stock of proteins, along with organelles such as the energy-producing mitochondria.

Synthesis (S) is the phase in which DNA replicates. During synthesis, the chromosomes replicate so that each chromosome is made up of two sister chromatids. At the end of this phase, there is double the amount of DNA in the cell.

Gap 2 (G₂) is another growth phase. The cell becomes even larger in order to prepare for mitotic division.

Mitosis (M)

Mitosis, or M phase, is when the cell begins to organize its duplicated DNA for separation into two daughter cells. The chromosomes separate so that one of each chromosome goes into each daughter cell. This results in the daughter cells having identical chromosomes to the parent cell. Mitosis itself is divided into prophase, metaphase, anaphase, and telophase, which mark various points in the DNA separation process. Mitosis is then followed by a process called cytokinesis, during which the cell separates its nuclei and other organelles in preparation for division and then physically divides into two cells.

Examples of Eukaryotic Cells

Plant Cells

Plant cells are unique among eukaryotic cells for several reasons. They have reinforced, relatively thick cell walls that are made mostly of cellulose and help maintain structural support in the plant. Each plant cell has a large vacuole in the center that allows it to maintain turgor pressure, which is pressure from having a lot of water in the cell and helps keep the plant upright. Plant cells also contain organelles called chloroplasts which contain the molecule chlorophyll. This important molecule is used in the process of photosynthesis, which is when a plant makes its own energy from sunlight, carbon dioxide, and water.

Fungal Cells

Like plant cells, fungal cells also have a cell wall, but their cell wall is made of chitin (the same substance found in insect exoskeletons). Some fungi have septa, which are holes that allow organelles and cytoplasm to pass between them. This makes the boundaries between different cells less clear.

Animal Cells

Animal cells do not have cell walls. Instead, they have only a plasma membrane. The lack of a cell wall allows animal cells to form many different shapes, and allows for the processes of phagocytosis "cell eating" and pinocytosis "cell drinking" to occur. Animal cells differ from plant cells in that they do not have chloroplasts and have smaller vacuoles instead of a large central vacuole.

Protozoa

Protozoa are eukaryotic organisms that consist of a single cell. They can move around and eat, and they digest food in vacuoles. Some protozoa have many cilia, which are small "arms" that allow them to move around. Some also have a thin layer called a pellicle, which provides support to the cell membrane.

Related Biology Terms

Cell - The basic biological unit of living things; they can be either prokaryotic or eukaryotic.

Mitosis - Part of the cell cycle, it is the process by which a cell replicates itself.

Eukaryote - An organism whose cells are eukaryotic.

Organelles - Specialized structures inside cells that perform specific cell functions.

Quiz

1. What are the three parts of interphase in the cell cycle?
A. Gap 1, Synthesis, Gap 2
B. Quiescence, Synthesis, Mitosis
C. Gap 1, Mitosis, Gap 2
D. Quiescence, Gap 1, Gap 2

2. Which is a possible characteristic of a eukaryotic cell?
A. Having a cell wall made of cellulose
B. Having a cell wall made of chitin
C. Having no cell wall
D. All of the above are seen in eukaryotic cells

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Eukaryotic Cell - Definition, Characteristics, Structure and Examples

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Eukaryotic cells are cells that contain a nucleus and organelles, and are enclosed by a plasma membrane. Organisms that have eukaryotic cells include protozoa, fungi, plants and animals. These organisms are grouped into the biological domain Eukaryota. Eukaryotic cells are larger and more complex than prokaryotic cells, which are found in Archaea and Bacteria, the other two domains of life.

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