1.2 - Cell Ultrastructures

Microscopes, Cells, Membranes Topics 1.1, 1.2, 1.3, and 1.4

Prokaryotes

Genetic material not in a nucleus (nucleoid)

Simple in structure

Unicellular

Do not have compartmentalized, membrane bound organelles (i.e. mitochondria, vacuole, rER).

Prokaryotic reproduction

**Binary Fission**

Asexual reproduction

Duplicates genetic material before splitting DNA and cytoplasm in half into two identical daughter cells.

Cell Membrane

Phospholipid bilayer. Surrounds cell and controls what travels in and out. Separates cell from environment

Cytoplasm

Liquid contents within the cell membrane

Site of metabolic reactions

Cell Wall

Located outside of the membrane

Provides structural support to the cell

ONLY FOUND IN PROKARYOTES AND PLANT CELLS

Pili

Attachment and Sex

**Attachment Pili:** Shorter in length, allow bacteria to adhere to one another and other surfaces

**Sex Pili:** Longer in length, allow for the exchange of genetic material via BACTERIAL CONJUGATION

Ribosomes

Site of protein synthesis.

Prokaryotes have 70s ribosomes which are smaller than eukaryotes

Eukaryotes have 80s free ribosomes which are bigger and float around the cytoplasm like 70s do.

They also have membrane bound 80s ribosomes on the Rough Endoplasmic Reticulum.

Nucleoid

Region in a prokaryote containing naked DNA. Not associated with any proteins

Cilia

Hair like structures that assist in mobility as well as moving extracellular materials.

Flagella

Long whip-like structures that are used as the ‘motors’ for movement

Eukaryotes

Complex organisms.

Have compartmentalized, membrane bound organelles.

DNA contained within a nucleus

Advantages in being compartmentalized

**Efficiency of metabolism:** enzymes and substrates can localize and be much more concentrated

**Localized conditions:** pH and other such factors can be kept at optimal levels. The optimal pH level for one process in one part of the cell.

**Toxic/damaging substances can be isolated:** digestive enzymes, i.e., that could digest the cell itself are stored in the lysosomes.

**Numbers and locations of organelles:** can be changed depending on the cell’s requirements.

Nucleus

Contains the cell’s genetic info in the form of chromosomes

Surrounded by a double membrane called the nuclear envelope

Site of DNA replication and transcription

Rough Endoplasmic Reticulum

Has ribosomes on its outer surface

Role is to package proteins for secretion. Sends them in vesicles to the Golgi apparatus.

Vesicles

Small sacs made of membrane.

Used to transport materials within the cell.

Golgi Apparatus

Processes proteins that are received from the rER

Sends them in vesicles to the cell membrane

Mitochondrion

Responsible for producing energy in the form of ATP

Done through cell respiration

Chloroplast

Responsible for photosynthesis, which converts light energy into chemical energy.

ONLY FOUND IN AUTOTROPHIC (make your own food) ORGANISMS

Microtubules

Fibers that play an important role in moving chromosomes during cell division. (lil grabby things that separate chromosome halves).

In animal cells microtubules are anchored at structures called centrioles.

Lysosomes

Membrane bound cell organelles that contain digestive enzymes.

Involved with various cell processes such as breaking down excess or worn out cell parts. They can also be used to destroy invading viruses and bacteria.

Vacuoles

Similar to vesicles. Made of membrane

Role is to store water.

Can be very large in plant cells and provide structural support when they are that big.