Module 2

Cells and Cell Structure

Cell

Cell

It is the fundamental unit of any living organism

Cytology

Study of Cell and its function

Cell Membrane

Also called as the plasma membrane which is the outermost component of a cell. It forms a boundary and encloses the cell, separating the contents of the cell to the outside world; selective permeable.

Nucleus

The command center of the cell

Nucleoplasm

Also called as protoplasm, it is a gelatinous base material of the nucleus.

Chromosomes

It is consist of linear DNA molecules and protein embedded in the nucleoplasm.

DNA

The genetic material that makes up the genes of chromosomes.

RNA

It participates in the conversion of the genetic code into proteins and other gene products.

Nuclear Membrane/Envelope

It serves as the skin of the nucleus; contains nuclear pores that allows passage and exit of different materials.

Cytoplasm

It is the interior of a cell which is a jelly-like, semifluid, gelatinous, nutrient matrix (cytosol) that surrounds the organelles.

Endoplasmic Reticulum

Highly convoluted system of membranes that are interconnected and arranged to form a transport network of tubules and flattened sacs within the cytoplasm.

Rough Endoplasmic Reticulum

It is the site for protein synthesis. It also transport materials through the cells.

Smooth Endoplasmic Reticulum

It transport material through the cells. It produces and digests lipids and membrane proteins. It also stores calcium ions. Lastly, it breaks down or detoxifies alcohol and drugs.

Ribosome

Site of protein synthesis. It can be attached to any other organelles.

Free Ribosome

Ribosomes that are not attached

Golgi Apparatus

This is where lipids and proteins mature. It is a stack of flattened, membranous sacs that completes the transformation of newly synthesized proteins into mature and functional ones.

Lysosomes

A membrane-bound vesicles formed from the golgi apparatus. It breaks down foreign material through phagocytosis. Garbage disposal unit of the cell

Peroxisomes

Small-membrane bound vesicle in which hydrogen peroxide is both generated and broken down. H2O2 is a byproduct of fatty/amino acid breakdown that can be toxic to the cell.

Mitochondria

Responsible for producing considerable amounts of ATP by aerobic. Powerhouse of the cell.

Plastid (Plant cell)

Membrane bound structure containing various photosynthetic pigments. This is the site for photosynthesis.

Cytoskeleton

System of fibers that serves to strengthen, support and stiffen the cell, and give the cell its shape. It gives internal framework to the cell.

Microtubules

Help support the cytoplasm, assist in cell division, and form essential components of cilia and flagella.

Microfilaments

Structurally support the cytoplasm, determining the cell shape.

Intermediate Filaments

Enables the cell to shorten or contract

Cell Wall (Plant Cell)

External structure that provides rigidity, shape, and protection to the cell.

Flagella

Have a structure similar to that cilia but are much longer and they are usually occur only one per cell. Long, thin, whip-like structure that enables the cell to “swim” in liquid environment.

Cilia

Shorter organelles compared to flagellaMicrovilli used for locomotion. They project from the structure of certain cells.

Microvilli

These are specialized extensions of the cell membrane that are supported by microfilaments; do not actively move as cilia and flagella.

Mitosis

The method of reproduction of eukaryotic cells wherein part of the cell is replicated then separated into two new nuclei.

Mesosomes

The inward folding of the cell membrane where cellular respiration takes place in bacteria.

Plasmid

Extrachromosomal DNA; circular molecules of double-stranded DNA

Glycocalyx

Slimy, gelatinous material produced by the cell membrane and secreted outside the cell wall. This determines the bacterial virulence produced intracellularly and secreted extracellularly.

Peritrichous

Flagella over the entire surface

Lophotrichous

Flagella at one end

Amphitrichous

One or more flagella at the end

Monotrichous

Single polar flagellum

Pili (Fimbriae)

hair-like structures, much thinner than flagella, have a rigid structure and are not associated with motility. They are organelles of attachment.

Normal Pili (Adherence)

Enables the bacteria to adhere/attach to any surface, have the ability to invade and attach themselves to any type of cells.

Sex Pili

Enables the bacteria to transfer genetic material from one bacteria to another, for replication and duplication within a host cell.

Spores (Endospores)

Formed as a means of survival when their moisture or nutrients is low.

Coccus

Spherical

Bacillus

Cylindrical rod

Vibrio

Short curved rod

Spirillum

Helical shaped corkscrew

Spirochete

Long helical cell and flexible

Diplococci

In pairs

Streptococci

Chains

Staphylococci

Clusters

Tetrads

Packets of four

Octads

Packets of eight

Binary Fission

The simple division of one cell intro two cells after DNA replication and the formation of separating membrane and cell wall.

Generation Time

Time it takes for one bacterial cell to divide into two.

Taxonomy

The Science of classifying living organisms

Genotype

Complete collection of genes; genetic characteristics

Phenotype

Physical characteristics

Carl Linnaeus

He developed the binomial system of nomenclature in the 18th century. It is composed of Genus + specific epithet.

Robert H. Wittaker

He proposed a Five Kingdom System of Classification in 1969. This includes the following:

1. Prokaryotae

2. Protista

3. Fungi

4. Animalia

5. Plantae

Carl Woese

He devised a Three Domain System of Classification (Archaea, Bacteria, and Eukarya)