2.3.1: Draw and label a diagram of the ultrastructure of a liver cell as an example of an animal cell 2.3.2: Annotate the diagram with the functions

Topic 2.3 Eukaryotic Cells

Assessment Statements

2.3.1: Draw and label a diagram of the ultrastructure of a liver cell as an example of an animal cell

2.3.2: Annotate the diagram with the functions of each named structure

2.3.3: Identify structures from 2.3.1 in electron micrograph of liver cells

2.3.4: Compare prokaryotic and eukaryotic cells 2.3.5: State three differences between plant and

animal cells 2.3.6: Outline two roles of extracellular

components

What is a eukaryotic cell?

Eukaryotic cells range in size: 5 to 100 µm (in diameter)

Most noticeable organelle: nucleus Others can be noticeable with high

enough resolution

What is a eukaryotic cell?

Organelles: are non-cellular structures that carry out specific functions Organelles found in cell vary with the

type of cell Organelles bring out

compartmentalization▪ Allows chemical reactions to be separated

(important because some chemical reactions are not compatible with others)

NOT in prokaryotic cells

Organelles of Eukaryotic Cells Common organelles:

Endoplasmic Reticulum (ER) Ribosomes Lysosomes (not usually in plants) Golgi apparatus Nucleus Chloroplasts (only in plant and algal cells) Centrosomes ▪ Centrioles (type of centrosomes—not in plants)

Vacuoles

Organelles of Eukaryotic Cells

Cytoplasm-not an organelle but a region All organelles occur within The fluid part between the organelles is

referred as the cytosol


Endoplasmic Reticulum Extensive network of tubules or channels

that extend almost everywhere in the cell from the nucleus to the plasma membrane▪ Enables the function of transportation of

materials throughout the internal region of the cell

Two general types▪ Smooth and Rough


Endoplasmic Reticulum (Smooth) Has no ribosomes attached to it Has many unique enzymes embedded on its

surface▪ Function:▪ Production of membrane phospholipids and cellular lipids▪ Production of sex hormones such as testosterone and estrogen▪ Detoxification of drugs in the liver▪ Storage of calcium ions needed for contraction in muscle cells▪ Transportation of lipid-based compounds▪ To aid the liver in releasing glucose into the bloodstream when

needed

Organelles of Eukaryotic Cells Endoplasmic Reticulum (Rough)

Has ribosomes on the exterior of the channels

Ribosomes involved in protein synthesis

Function:▪ Protein development and transport

Most cells contain both types of ER with the rough being closer to the nuclear membrane


Ribosome Not have a exterior membrane Function: Protein synthesis Can be found free (in cytoplasm) or

attached (ER) Found in both Eukaryotic and

Prokaryotic cells▪ Ribosomes found in eukaryotic cells are

larger and denser then ones in prokaryotic cells

▪ All ribosomes contain 2 subunits ▪ Eukaryotic: 80S▪ Prokaryotic 70S


Lysosomes Intracellular digestive centers (come from

Golgi ) No internal structures They are sacs bounded by a single

membrane but contain as many as 40 different hydrolytic enzymes (very acidic)

Function: Fuse the old or damaged organelles from within the cell to break them down so that recycling of the components may occur▪ Also involved breakdown of materials brought

into cell by phagocytosis


Golgi Apparatus Consists of flattened sacs called

cisternae (stacked on top of eachother)

Functions: in collection, packaging, modification, and distribution of materials synthesized in cell▪ Cis side-near ER, to receive product▪ Move into the cisternae of the Golgi

▪ Trans side-product is discharged from▪ small sacs called vesicles are released from this

side These carry modified materials to wherever

they are needed inside and outside the cell


Mitochondria Rod shaped organelle that appear

throughout the cytoplasm (same size as a bacterial cell)

Has their own DNA, circular Double Membrane-Outer (smooth),

Inner (Folded into cristae)▪ Inside the inner membrane is a semi-

fluid substance called matrix▪ Inner membrane spaces-lies between the

two membranes


Mitochondria-Function The cristae provides huge internal

surface area for chemical reactions to occur▪ Most chemical reactions involve the

production of usable cellular energy-ATP

Contains its own ribosomes (70S type)

Cells that have high energy requirements, such as muscle cells, have a large numbers of mitochondria

Organelles of Eukaryotic Cells Nucleus-is an isolated region where the DNA

resides Bordered by a double membrane referred to as the

nuclear envelope▪ Allows for separation for the DNA—providing an area

where DNA can carry out its functions and not be affected by the other parts of a cell

▪ DNA (genetic material) is usually found in a form of chromosomes▪ Carry all the information necessary for the cell to exist (allows for

survival)

▪ DNA is only found in the form of chromatin during cellular division (formed from histones and DNA (nucleosome)▪ Nucleosome consists of 8 histones with a DNA wrapped around them


Nucleus Usually located centrally in

the cell Most cells only contain one! Cannot reproduce without a

nucleus▪ Only found in very specialized

cells (example: blood) Nucleolus: dark area inside

the nucleus▪ Function of nucleolus:

production of ribsomes


Chloroplast Only occurs in plant and algae cells Double membrane and is about the size of a

bacterial cell▪ Contains its own DNA (circular) and 70S ribosomes

Also contains granum, thylakoid, and stroma▪ Granum-is made up of numerous thylakoids stacked

in a pile▪ Thylakoid-are flattened membrane sacs with

components necessary for absorption of light ▪ Stroma-similar to cytosol: occurs outside the grana

but within the double membrane (contains enzymes and chemicals necessary to complete photosynthesis


Centrosome Occurs in all eukaryotic

cells▪ Consists of a pair of

centrioles at a right angle to one another▪ Involved in assembling

microtubules (important for movement, structure, and cell division)

▪ Plants do not have centrioles but the centrosome is located at one end of the cell close to the nucleus


Vacuoles-are storage organelles that usually form from the Golgi Apparatus Membrane bound and have many

possible functions Plant cells-occupy VERY large area

inside the cell▪ Allows an uptake of water that provides

rigidity Function: storage of number of different

substances including potential food, metabolic wastes and toxins, and water▪ Enable cells to have higher surface area to

volume ratio

Comparison of Prokaryotic and Eukaryotic cells (differences)

Prokaryotic Cells Eukaryotic Cells

DNA in a ring form without protein

DNA with proteins as chromosomes/chromatin

DNA free in the cytoplasm (nucleoid region)

DNA enclosed within a nuclear envelope (nucleus)

No mitochondria Mitochondria present

70S ribosome 80S ribosome

No internal compartmentalization to form organelles

Internal compartmentalization present to form many types of organelle

Size less than 10 µm Size more than 10 µm

Comparison of Prokaryotic and Eukaryotic cells

Similarities: Both types of cells have some sort of

outside boundary that always involves a plasma membrane

Both types of cell carry out all the functions of life

DNA is present in both cell types

Comparison of Plant and Animal cells (differences)

Plant cells Animal Cells

Exterior of cell includes an outer cell wall with a plasma membrane just inside

Exterior of cell includes only a plasma membrane. There is not cell wall

Chloroplasts are present in the cytoplasm

There are not chloroplasts

Possess large centrally located vacuoles

Vacuoles are usually not present or Very small

Store carbohydrates as starch Store carbohydrates as glycogen

Do not contain centrioles within a centrosome area

Contain centrioles within a centrosome area

Because a rigid cell wall is present, this cell type has a fixed, often angular, shape

Without cell wall, this cell is flexible and more likely to be rounded shape

Comparison of Plant and Animal cells

The outermost region of various cell types is often unique:

Cell Outermost partBacteria Cell wall of Peptidoglycan

Fungi Cell wall of Chitin

Yeasts Cell wall of glucan and mannan

Algae Cell wall of cellulose

Plants Cell wall of cellulose

Animals No cell wall: plasma membrane secretes a mixture of sugar and proteins called Glycoproteins that form the extracellular matix

Extracellular matrix (ECM): Extracellular matrix (ECM): composed of

collagen fibers plus a combination of sugars and proteins called glycoproteins Fiber-like structures that anchor the matrix to

the plasma membrane—strengthens the plasma membrane and allows attachment between adjacent cells

ECM allows for cell to cell interaction (many researchers believe it is involved in directing stem cells to differentiate)

Documents

2.3.1: Draw and label a diagram of the ultrastructure of a liver cell as an example of an animal cell 2.3.2: Annotate the diagram with the functions