Eukaryotic Cell Structure

7.2

Biology

Mr. Hines

Comparing the cell to a factory

In order for a cell to maintain its internal environment (homeostasis), many things must go on.

This is similar to a factory. Things come and go in and out of a factory in an orderly fashion.

Things come and go in cells too, they are just very small.

Prokaryotic Cell

Cell membrane

Cell membrane

Cytoplasm

Cytoplasm

Nucleus

Organelles

Eukaryotic Cell

Section 7-1

Prokaryotic and Eukaryotic Cells

There are many structures in cells which perform different tasks. These structures are called organelles.

Organelle - specialized structure that performs important cellular functions within a eukaryotic cell

Cells are divided up into 2 main sections.a. cytoplasm - material inside the cell membrane—not including the nucleusb. nucleus - Control center of cell containing DNA

NucleusThe nucleus contains nearly all the cell’s DNA and

with it the coded instructions for making proteins and other important molecules

The nucleus is surrounded by a nuclear envelope composed of 2 membranes.

The nuclear membrane contains thousands of pores which allow materials to flow in and out.

The nucleus controls what goes on in the cell by sending chemical instructions through this membrane

The granular material inside of the nucleus is

called chromatin. Chromatin is made of DNA wound around proteins.

When the cell is about to divide, the chromatin coils up into chromosomes.

The nucleus also contains a smaller structure called the nucleolus.

The nucleolus is a dense region where the assembly of ribosomes begins.

RibosomesOne of the most important functions in a cell

is the production of proteins.Ribosomes are small particles of RNA and

Protein.Ribsomes make proteins. They do this by

following coded instructions from the nucleus (the boss)

Ribsomes are found in the cytoplasm and on the Endoplasmic reticulum.

Endoplasmic Reticulum (ER)

The endoplasmic reticulum is the site where lipid components of the cell membrane are assembled, along with proteins and other materials that are exported from the cell.

There are 2 kinds of ERa. Smooth ER – does not have ribosomesb. Rough ER – does have ribosomes

When ribosomes located on the rough ER make protein, the proteins are moved inside to the ER where it is chemically modified and sent to its needed location.

The smooth ER creates lipids for the cell membrane and detoxifies various chemicals.

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Golgi Apparatus

The golgi apparatus is composed of stacks of membranes.

The function of the golgi apparatus is to modify, sort, and package proteins and other materials from the endoplasmic reticulum for storage in the cell or secretion outside the cell.

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Cytoskeleton

Cytoskeleton is a network of protein filaments that helps the cell to maintain its shape. The cytoskeleton is also involved in movement.

There are 2 componets of the cytoskeleton1. Microtubules – hollow tubes made of proteins2. Microfiliments – threadlike structures made of

proteinMicrotubles and microfiliments are used by

microorganisms to move. (cilia and flagella)

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Lysosomes Lysosomes are small organelles filled with

enzymes (proteins)Lysosomes sort of clean up the cell.Lysosomes breakdown macromolecules such

as carbohydrates, lipids, and proteins into their monomers so they can be reused somewhere else.

Lysosomes will also disassemble organelles that are no longer useful to the cell.

Centrioles

Centrioles are structures made of proteins that help control the process of cell division.

Centrioles are not found in plant cells.

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Mitochondria

Mitochondria are located all over a cell’s cytoplasm.

Mitochondria convert the chemical energy stored in carbohydrates into simple compounds so the energy can be used.

Mitochondria is also called the “powerhouse” of the cell because it provides energy.

2 interesting facts.

1. Where did you get your mitochondria? From mom or dad? When the sperm fertilizes the egg, the sperm cell donates only DNA and no mitochondria. Your mitochondria are all from mom

2. Mitochondria have their own DNA and can reproduce themselves. It is theorized that before the time of living cells, mitochondria existed alone

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Cell membrane

Endoplasmicreticulum

Microtubule

Microfilament

Ribosomes Mitochondrion

Section 7-2

Figure 7-11 Cytoskeleton

Plant cell organelles

Plants have 2 organelles that are not found in animal cells.

1. Chloroplasts

2. Vacuole

3. Cell Wall

Chloroplasts Chloroplasts are organelles that capture the

energy from sunlight and covert it into chemical energy in a process called photosynthesis (create carbohydrates)

Chloroplasts are located in the cytoplasm of plant cells, some protists, and some bacteria.

Chloroplasts contain chlorophyll

1 interesting fact.

Chloroplasts have their own DNA and can reproduce themselves. It is theorized that before the time of living cells, chloroplasts existed alone

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VacuolesVacuoles are membrane bound organelles that

store carbohydrates, proteins, salts, or water.

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Animal Cell

Centrioles

NucleolusNucleus

Nuclearenvelope

Rough endoplasmic reticulum

Golgi apparatus

Smooth endoplasmicreticulum

Mitochondrion

CellMembrane

Ribosome(free)

Ribosome(attached)

Section 7-2

Figure 7-5 Plant and Animal Cells

Plant Cell

Nuclearenvelope

Ribosome(attached)

Ribosome(free)

Smooth endoplasmicreticulum

Nucleus

Rough endoplasmic reticulum

Nucleolus

Golgi apparatus

Mitochondrion

Cell wall

CellMembrane

Chloroplast

Vacuole

Section 7-2

Figure 7-5 Plant and Animal Cells

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