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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
Organelles of Eukaryotic Cells
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
Organelles of Eukaryotic Cells
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
Organelles of Eukaryotic Cells
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
Organelles of Eukaryotic Cells
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
Organelles of Eukaryotic Cells
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
Organelles of Eukaryotic Cells
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
Organelles of Eukaryotic Cells
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
Organelles of Eukaryotic Cells
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
Organelles of Eukaryotic Cells
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
Organelles of Eukaryotic Cells
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
Organelles of Eukaryotic Cells
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)