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 micrographs of liver cell
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
EUKARYOTIC CELLS
Eu = True, karyon meaning ‘kernel’, referring to the nucleus  True
Nucleus
The general size of a eukaryotic cell is about 5-100 um.
The ribosomes are larger than eukaryotic cells (80S versus 70S
ribosomes)
Compartmentalization allows chemical reactions to be separated
increasing the efficiency of the cell
ORGANELLES
Endoplasmic Reticulum
Ribosomes
Lysosomes (not usually in plant cells)
Golgi Apparatus
Mitochondria
Nucleus
Chloroplasts (only in plant cells)
Vacuoles
ENDOPLASMIC RETICULUM
Extensive netowrk of tubules or channels that extends almost eveywhere in the cell
from the nucleus to the plasma membrane
Function: transportation of materials throughout the internal region of the cell
Smooth ER
Rough ER
Produces membrane phospholipids and
cellular lipids
Involved in protein development and
transport (function as support for
ribosomes)
Produces sex hormones (testosterone and
estrogen)
Detoxifies drugs in the liver
Stores calcium ions needed for contraction in
muscle cells
Transport lipid based compounds
Aid the liver in releasing glucose into the
bloodstream when needed
RIBOSOMES
Carry out protein synthesis
Can be free in the cytoplasm or attached to the rough ER
Composed of RNA and protein
Larger and denser in eukaryotes vs prokaryotes
Composed of two subunits (80S)
LYSOSOMES
Digestive centers the arise from the Golgi apparatus
Sacs of hydrolytic enzymes the catalyze the breakdown of proteins, nucleic acids,
lipids and carbohydrates
Fuse with old or damaged organelles to recycle the components
Responsible for breaking down materials brought into the cell by phagocytosis
The interior of a functioning lysosome is acidic
GOLGI APPARATUS
Composed of flattened sacs called cisternae
Functions in the collection, packaging, modification, and distribution of materials
synthesized in the cell
One side is always close to the rough ER (cis side) receiving products from the ER
Movement occurs to discharge the product from the opposite (trans) side. Small sacs,
called vesicles, can be seen coming off the trans side carrying modified materials to
wherever they are needed inside or outside the cell.
Prevalent in glandular cells that manufacture and secrete substances (ex. in the pancreas)
MITOCHONDRIA
Have their own DNA! (a circular chromosome similar to that in bacterial cells)
Double membrane – smooth on the outside, folded on the inside
Reactions within produce usuable cellular energy (ATP), where it gets its nickname
‘the powerhouse’
Produces and contains its own ribosomes (70S)
Cells that have high energy requirements, such as muscle cells, have large numbers
of mitochondria
NUCLEUS
Isolated region housing the DNA in the form of chromosomes (strands of DNA
wrapped around histones [protein])
Double membrane  nuclear envelope (allows for compartmentalization – providing
an area where DNA can carry out its functions and not be affected by processes
occurring in other parts of the cell)
Nuclear pores in the nuclear membrane allow communication with the cell’s
cytoplasm
CHLOROPLASTS
ONLY in algae and plant cells!
Double membrane, about the same size as mitochondrion
Has its own DNA (in the form of a ring) and 70S ribosomes
Grana (pile of thylakoids) + stroma (fluid containing enzymes necessary for
photosynthesis)
Can reproduce independently of cell
VACUOLE
Storage organelles the usually form from the Golgi apparatus
Occupy large space in plant cells
Can store food, metabolic wastes and toxins, and water
Enable cells to have higher surface area to volume ratios
In plants, they allow an uptake of water providing rigidity
CENTROSOME
Generally contains a pair of centrioles which are involved in assembling microtubules
(important in providing cell structure and allowing movement)
Important to cell division
Higher plant cells produce microtubules even though they do not have centrioles
Located at one end of the cell, close to the nucleus
Prokaryotic Cells
Eukaryotic Cells
DNA in ring form without histones
DNA with protein as
chromosomes/chromatin
DNA free in cytoplasm (nucleoid region)
DNA enclosed in a nuclear envelope
No mitochondria
Mitochondria present
70S ribosomes
80S ribosomes
No internal compartmentalization to form
organelles
Internal compartmentalization present to
form many types of organelle
Size = less than 10 micrometers
Size = more than 10 micrometers
SIMILARITIES OF PROKARYOTIC AND
EUKARYOTIC CELLS
1. Both types of cell have some sort of outside boundary that
always involves a plasma membrane
2. Both types carry out all the functions of life
3. DNA is present in both cell types
EUKARYOTIC CELLS
Plant Cells
Animal Cells
Exterior of cell includes an outer cell wall
with a cell membrane just inside
Exterior of cell includes only a cell
membrane
Chloroplasts present in the cytoplasm
No chloroplasts
Possess large centrally located vacuoles
Vacuoles are usually small or non existent
Store carbohydrates as starch
Store carbohydrates as glycogen
Do not contain centrioles within a
centrosome area
Contain centrioles within a centrosome
area
Fixed, often angular shape (because of
rigid cell wall)
Cell is flexible and usually round