1.2 Ultrastructure of CellsProkaryotes and Eukaryotes

“primitive cells”

cells that lack membrane-bound organelles

ie: no nucleus, no mitochondria, no vacuoles, etc

Ex: bacteria (ie E. Coli) – found in soil, water, on your skin, in your intestine

Ex: blue green algae

Prokaryotic Cells

organisms that are made of prokaryotic cells.

Most prokaryotes are unicellular, such as bacteria, however, they can be multicellular too, such as blue green algae

Prokaryotes

E. coli

Blue- Green Algae

Prokaryote Cell Structure

Prokaryote Cell Structue

CELL SURFACE MEMBRANE / PLASMA MEMBRANE: Thin layer composed of phospholipids Controls the entry/ exit of substance via active

or passive transport Selectively permeable

Prokaryote Cell Parts

CELL WALL: Rigid to semi-rigid wall surrounding the plasma

membrane. Contains pores to allow passage of materials in

and out of the cell. The Cell wall supports the cell and provides

shape

Prokaryote Cell Parts

SLIME CAPSULE: Protective outside layer, found outside the cell

wall Also known as “surface layer” or the “S-layer” Protects the cell from environmental dangers Contains proteins and or glycoproteins

Prokaryote Cell Parts

Cytoplasm: The “inside” of the cell Contains cytosol (fluid of the cell) Contains the enzymes (biological catalysts) for

catalyzing chemical reactions of metabolism Contains ribosomes and naked DNA No membrane bound organelles!

Prokaryote Cell Parts

NUCLEOID: Region of the prokaryotic cytoplasm where

genetic information is found (1 main chromosome and plasmids)

The 1 chromosome is made of NAKED DNA This means that the DNA is not bound to proteins

(like histones) This reduces the amount of space they take up Usually circular

Prokaryote Cell Parts

PLASMID: Small, circular, naked, DNA Smaller, and contains less information than the

chromosome. Found in the cytoplasm

Prokaryote Cell Parts

Mesosome: Indentation in the cell membrane of bacteria Unknown function, produced by chemical

fixation techniques.

Prokaryote Cell Parts

RIBSOSOME: Made of RNA and proteins Makes proteins Less dense than eukaryotic ribosomes

Prokaryote Cell Parts

FLAGELLUM: threadlike, motile proteins structures and are

used for locomotion Cell may have none, 1, or several

Prokaryote Cell Parts

PILI (plr) / PILUS (singular): Thin protein tubes found outside the plasma

membrane and extend out from the slime capsule

Attachment Pili Have sticky ends that allow it to attach to

surfaces (i.e. another cell) Conjugation Pili (Sex Pili)

Longer Build a bridge between 2 bacterial cells allowing

for exchange of DNA (conjugation)

Prokaryote Cell Parts

Prokaryotic cells divide asexually by binary fission (similar to mitosis)

They duplicate their chromosome (their circular DNA) and then split in half (each new daughter cell gets half the cytoplasm and 1 chromosome)

Prokaryotic Reproduction

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Since binary fission is a form of asexual reproduction, the daughter cells produced are identical to the original parent cell.

Conjugation (with the help of conjugation pili) allows for genetic variation – allows for a new combination of DNA

http://www.google.ca/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=W5iSnr2trdLYeM&tbnid=AFrw59Rim4K-XM:&ved=0CAUQjRw&url=http://academic.pgcc.edu/~kroberts/Lecture/Chapter%207/horizontal.html&ei=po36UvKOM8i92wWy8YCABg&bvm=bv.61190604,d.aWc&psig=AFQjCNEWgqQ_D76mtSc6qEUGyusN9KdXNQ&ust=1392238348682531

Annotate and Identify Structures from and electron micrograph of E. Coli

ribosome

Nucleoid region (DNA, plasmid)Cell wall

cytoplasmPlasma membrane

No visible slime capsule in this diagram

PILUS

SLIME LAYER

Metabolic Activity of Prokaryotic Cells

1. Photosynthesis: light + CO2 + H2O C6H12O6 + O2

2. Nitrogen Fixation: Convert nitrogen from an unusable from to a usable form

3. Fermentation: convert organic substances into simpler substances (ie sugar into ethanol)

complex cells with membrane bound organelles Ex: the cells that make up you! (and other

animals) Ex: plant cells

STRUCTURE: all eukaryotes contain: Plasma membrane Central nucleus with DNA Membrane bound organelles in the cytoplasm

Eukaryotic Cells

Plasma Membrane: Outer surface of animal cells Made of phospholipid bilayer Controls the entry and exit of

molecules

Eukaryotic Organelles

Nucleus: Control center of the cell Largest organelle Surrounded by a double membrane (nuclear envelope) Contains chromosomes – made of DNA and proteins

Nuclear Envelope: Controls entry and exit of molecules Contains nuclear pores (openings)

Eukaryotic Organelles

Chromosomes: Contains hereditary info Made of DNA and proteins

Nucleolus: In center of nucleus Makes ribosomes

Eukaryotic Organelles

Endoplasmic Reticulum: Tubules for transport and synthesis of large

organic molecules Often continuous with the nuclear envelope RER – rough ER – has ribosomes SER – smooth ER – makes carbs and lipids

Eukaryotic Organelles

Ribosomes: Made of proteins and RNA Site of protein synthesis

Lysosomes: “suicide sac” Contains digestive enzymes breakdown of macromolecules Digest worn-out cell parts/organelles Digest pathogens Can cause cell death if it breaks open (cell

lysis) and releases enzymes

Eukaryotic Organelles

Mitochondrion: Site of cellular respiration Makes ATP (adenosine triphosphate) energy for the cell Double membrane Has its own DNA (mDNA) Own ribosomes

Chloroplast: Site of photosynthesis (makes sugar from light energy) Has double membrane, own DNA, own ribosomes

Eukaryotic Organelles

Flagella: Long microtubules strand “whiplike” tail For motility

Cillia: Short microtuble strands For motility

Eukaryotic Organelles

Golgi Apparatus/Golgi Body/Golgi Complex: Looks like a stack of deflated balloons Membranous sacs “Packaging plant” of the cell Packages cell products (ie: carbs and lipids)

Vacuoles: Membrane bound organelles used for storage of

water, wastes, and macromolecules

Eukaryotic Organelles

Cell Wall: Rigid outer layer of plant cells Made of cellulose

Plasmodesmata: Gaps in cell walls Create junctions between plant cells

Eukaryotic Organelles

Atypical Cells Striated Muscle Muscle Fibres

(Muscle Cells) Longer than

typical cells (30mm opposed to <0.3mm)

Multiple nuclei

Atypical Cells Giant Algae Ex Acetabularia, a

unicellular organism, can grow to a length of 10 cm, despite having only 1 nucleus.

Usually organisms that large consist of several cells.

Atypical Cells Aseptate Hyphae Narrow thread like

structure in fungi Have a cell wall

and membrane. In aseptate fungi,

the hyphae is an uninterrupted tube-like structure with many nuclei spread along it.

Animal vs Plant Cells

ANIMAL CELL No chloroplasts No cell wall Usually no large central

vacuole Carbohydrates stored as

glycogen Have lysosomes Amorphic shape

PLANT CELL Chloroplasts usually present Cell wall present Have large central vacuole

Carbohydrates stored as starch or cellulose

Generally lack lysosomes Rigid shape, often with

straight edges

Prokaryotic Cell vs Eukaryotic Cell

PROKARYOTES Do not have membrane

bound organelles Naked circular DNA (no

proteins associated) DNA in nucleoid region RIBOSOMES: free floating

in cytoplasm No mitochondria; uses

plasma membrane for respiration

EUKARYOTES Membrane bound

organelles present DNA wrapped around

histone proteins DNA within the nucleus Ribosomes: attached to

RER or free floating in cytoplasm

Has mitochondria for aerobic cellular respiration