3.3 Eukaryotic Cells

It should be clear that prokaryotic cells have a more complex structure than eukaryotic cells.

Functions can occur in the cell at the same time.
Before we discuss the functions of the cell's organelles, we need to look at the two most important parts of the cell.

The figure shows a typical animal and plant cell.

Alipid is a molecule composed of two acid chains and a glycerol backbone.

The passage of some substances, such as organic molecule, ion, and water, can be prevented by the plasma membrane, which regulates the passage of some substances.
Other compounds don't move much.

There is a bilayer oflipids in the plasma membrane.

Cholesterol and carbohydrates can be found in the membranes, along with other components.

The cells that specialize in absorption are folded into tiny projections called microvilli.

The surface area is increased by folding.
The cells are found in the lining of the small intestine.
This is an example of form matching a structure.

People with the disease have an immune response to wheat, barley, and rye.

Microvilli are damaged by the immune response and afflicted individuals can't absorb vitamins.
This leads to dehydration.
Patients with the disease have to follow a diet that is free of wheat.

There are other organic molecules in the cytoplasm.

There are also simple sugars and derivatives of glycerol found there.
The elements are dissolved in the cytoplasm.
The cytoplasm is where many metabolic reactions take place.

There are ion and organic molecules in the cell's cytoplasm, as well as a network of protein fibers that help to maintain the cell's shape, as well as the ability for unicellular organisms to move independently.

Microfilaments, actin filaments, and intermediate filaments are three types of fibers within the cytoskeleton.

The cell's cytoskeleton is composed of microfilaments, intermediate filaments, and microtubules.

Microfilaments are the smallest of the fibers and are used in moving cellular components.

The structure of microvilli, the extensive folding of the plasma membrane, is maintained by them.
These components are found in muscle cells.

Intermediate filaments are of intermediate diameter and have structural functions.

The compound that strengthens hair and nails is called Keratin.

The smallest of the cytoskeletal fibers is called a microtubule.

These hollow tubes can be dissolved quickly.

The structures that pull chromosomes to their poles are called microtubules.

They are part of flagella and cilia.

There are nine double microtubules on the outside and two on the center in flagella.

The centrosome is located near the nucleus of animal cells and is a microtubule-organizing center.

There are two structures that lie close to each other.
There are nine triplets of microtubules in a centriole.

The centrosome replicates itself before a cell divides, and the centrioles play a role in pulling duplicated chromosomes to opposite ends of the dividing cell.

The function of the centrioles in cell division is not clear, since cells that have the centrioles removed can still divide, and plant cells, which lack centrioles, are capable of cell division.

There is only one flagellum or a few flagella in the cell.

They are short, hair-like structures that are used to move entire cells or substances along the outer surface of the cell.

There is a group of cells that work together to modify, package, and transport.

We will cover the nuclear envelope, lysosomes, and vesicles soon.

The nuclear envelope is the outer boundary of the nucleus.

The nuclear envelope consists of two phospholipid bilayers, an outer and an inner one.

The nuclear envelope has pores that control the passage of things between the nucleus and the cytoplasm.

It is helpful to first consider the chromosomes.

There are structures within the nucleus that are made up of genes.
There is a combination of genes.
The chromosomes are linear structures.
Every species has a specific number of chromosomes.
In fruit flies, the chromosomes number is eight, whereas in humans it is 46.

When a cell is getting ready to divide, chymosomes are only visible.

The chromosomes look like an unwound bunch of threads when the cell is in the growth and maintenance phases.

ribosomal RNA is found in some of the chromosomes.

The rough and smooth areas of the reticulum are where these two functions are performed.

The cisternal space is the hollow portion of the ER tubules.

The nuclear envelope is continuous with the ER's phospholipid bilayer.

While attached to the ER, the ribosomes transfer their newly synthesized proteins into the RER where they undergo modifications such as folding or addition of sugars.

The RER makes conjugates for cells.

If the modified proteins are not destined to stay in the RER, they will be packaged within the vesicles and transported from the RER.

The RER is involved in modifying the genes that will be produced from the cell.

The SER's functions include steroid hormones, cholesterol synthesis, alcohol metabolism, and calcium ion storage.

The transport vesicles need to be sorted, packaged, and tagged before they reach their final destination.

The Golgi apparatus in this transmission electron micrograph of a white blood cell is visible as a stack of semicircular flattened rings in the lower portion of the image.
There are several vesicles near the Golgi apparatus.

The transport vesicles that form from the ER travel to the receiving face and empty their contents into the Golgi apparatus.

Modifications are made to the proteins and lipids as they travel through the Golgi.
The addition of short chains of sugar is the most frequent modification.
The newly modified genes are tagged with small groups so they can be routed to their destinations.

The vesicles that bud from the opposite face of the Golgi are modified and tagged.

While some of these vesicles, transport vesicles, deposit their contents into other parts of the cell where they will be used, others, secretory vesicles, release their contents outside the cell.

The amount of Golgi in different cell types shows that form follows function.

Cells that engage in a lot of secretory activity have a lot of Golgi.

Some of the Golgi's work is incorporated into the cell wall and some of it is used in other parts of the cell.

The lysosomes aid in the breakdown of many substances.

lysosomes are important for the digestion and recycling of food in single-celled eukaryotes.
The enzymes are more acidic than the ones in the cytoplasm.
Many reactions that take place in the cytoplasm could not be done at a low pH.

Disease-causing organisms that might enter the cell are destroyed by lysosomes.

A group of white blood cells called macrophages are part of your body's immune system.
A section of the macrophage invaginates (folds in) is engulfed by a pathogen in a process known as phagocytosis.
The invaginated section with the pathogen inside becomes a vesicle.
There is a lysosome in the vesicle.

A macrophage has destroyed a potentially pathogenic bacterium by attaching a lysosome to it in the cell.

For simplicity, the other organelles are not shown.

The vacuole is larger than the other components of the cell.

Vesicles can connect with other cells.
The plant vacuoles can break down macromolecules.

The endomembrane system works to modify and package.

When viewed through an electron microscope, ribosomes appear to be either clusters or tiny dots.

Large and small ribosomes can be attached to either side of the reticulum.
Ribosomes are involved in the synthesis of proteins.

ribosomes are found in almost every cell, even though they are smaller in prokaryotic cells.

They are abundant in immature red blood cells, which play a key role in the transport of oxygen throughout the body.

Cellular respiration is the process by which the breakdown of sugar leads to the formation of a molecule of a molecule of a molecule of a molecule of a molecule of a molecule of a molecule of a molecule of a molecule of a molecule of a molecule of a molecule of a molecule of a molecule of Mitochondria have their own ribosomes and DNA.

There is a bilayer embedded in the membrane.
The inner layer has folds called cristae, which increase the surface area.
The mitochondrial matrix is surrounded by folds.
The cristae and matrix play different roles in cellular respiration.

In keeping with our theme of form following function, it is important to point out that muscle cells have a high concentration of mitochondria because they need a lot of energy to contract.

This transmission electron micrograph shows achondrion.

The oxidation reactions break down the acids.

Many poisons can enter the body.
Alcohol is removed from the cells of the body.
H2O2 is contained within the peroxisomes to prevent it from damaging cellular components outside of the organelle.
Hydrogen peroxide can be broken down into water and oxygen.

There are some striking differences between animal and plant cells, such as centrioles, centrosomes, and lysosomes.

Plant cells have a large central vacuole and a cell wall, while animal cells do not.

The protist cells have cell walls.

The major organic molecule in the plant cell wall is a polysaccharide made up of long, straight chains of glucose units.

The information about nutrition refers to the content of the food.

Chlorops have their own genes and ribosomes.

Light energy, water, and carbon dioxide are used to make food.
The major difference between plants and animals is that plants can make their own food, while animals must rely on other organisms for their organic compounds or food source.

There is a set of stacked, fluid-filled sacs called thylakoids in the space between the chloroplast's outer and inner membranes.

The stroma is the fluid that surrounds the grana.

The diagram shows the outer, inner, and stroma of a chloroplast.

The energy of the sun's rays is captured by the green pigment in the chloroplasts.

Protists have the same cells as plant cells.
Somebacteria do not have chloroplasts.
The cell has a thylakoid membrane.

Both the mitochondria and the chloroplasts contain ribosomes.

There is strong evidence that explains the explanation.

Symbiosis is a relationship in which organisms from two different species live in close association.

There is a relationship in which organisms live inside each other.
Nature has a lot ofycorrhizal relationships.
The human gut hasMicrobes that produceVitamin K. The relationship is beneficial for us because we can't make vitamins K and K2 and it's also beneficial for the microbes because they are protected from other organisms.

Scientists have noticed that the organisms are the same size.

We know that the cells of the mitochondria and the cells of the chloroplasts have the same genetic material.
Scientists believe that host cells andbacteria formed a beneficial relationship when the host cells ate aerobicbacteria but did not destroy them.
The aerobic and the photosyntheticbacteria became specialized in their functions through evolution.

vacuoles are essential components of plant cells.

Plants have a large central vacuole that occupies most of the cell.
Turgor pressure is the outward pressure caused by the fluid inside the cell and is provided by the liquid inside the central vacuole.
Water moves out of the central vacuoles and into the soil when the water concentration in the soil is lower than in the plant.
The cell wall is supported by the central vacuole.
The bitter taste of this fluid discourages insects and animals from consuming it.

The central vacuole has a function to store proteins.

The main components of these materials are glycoproteins.

The cells within the tissue can communicate with each other thanks to the extracellular matrix.

The network of substances in the matrix are produced by cells.

Blood clotting shows the role of the matrix in cell communication.

When a blood vessel is damaged, the cells in it display a tissue factor.
When tissue factor binding with another factor in the extracellular matrix causes platelets to adhere to the wall of the damaged blood vessel, it stimulates adjacent smooth muscle cells in the blood vessel to contract, and causes a series of steps that stimulates the platelets to produce clotting factors.

Intercellular junctions are where cells can communicate with each other.

Plants and animals do this in different ways.

The cells of the same plant can't touch each other because they are separated by the cell walls.

There are connections between cells.

The cells are held against each other by the proteins.

The materials are not leaking between the cells.
Most of the skin is composed of tight junctions in the epithelial tissue that lines internal organs.
The tight junctions of the cells in the bladder prevent urine from leaking.

They keep cells together in tissues that stretch like the skin, heart, and muscles.

The components of prokaryotic and eukaryotic cells can be found in this table.