CELL BIOLOGY

What is Cell Biology? Cell Biology (formerly called cytology)is a branch

of biology that studies the different structures and functions of the cell and focuses mainly on the idea of the cell as the basic unit of life.

Cell biology explains the structure, organization of the organelles they contain, their physiological properties, metabolic processes, signaling pathways, life cycle, and interactions with their environment.

 Research in cell biology is closely related to genetics, biochemistry, molecular biology, immunology, and developmental biology.

Cell Structure

Cell Diversity

Cell size

Classification of Cell  The cell shape varies among the different types of

organisms Two categories: Eukaryotes and Prokaryotes Eukaryotic cells - which are made up of animal, plant,

fungi, and protozoa cells - the shapes are generally round and spherical.

 Prokaryotic cells – which are composed of bacteria and archaea - the shapes are: spherical (cocci), rods (bacillus), curved (vibrio) and spirals

Focus on Cell Biology  Cell biology focuses more on the study of eukaryotic cells,

and their signaling pathways, rather than on prokaryotes which is covered under microbiology.

The main constituents of the general molecular composition of the cell includes: proteins and lipids.

This environment of the cell is made of hydrophilic and hydrophobic regions which allows for the exchange of the above-mentioned molecules and ions.

 The cell membrane consists of lipids and proteins which accounts for its hydrophobicity as a result of being non-polar substances. Therefore, in order for these molecules to participate in reactions, within the cell, they need to be able to cross this membrane layer to get into the cell. 

Cell Cycle

Growth and Development The growth process of the cell does not refer to the

size of the cell, but instead the density of the number of cells present in the organism at a given time.

Cell growth pertains to the increase in the number of cells present in an organism as it grows and develops; as the organism gets larger so too does the number of cells present.

Cell goes through the steps of the cell cycle and development which involves cell growth, DNA replication, cell division, regeneration, specialization, and cell death.

The cell cycle is regulated by a series of signaling factors and complexes such as CDK's, kinases, andp53. to name a few.

When the cell has completed its growth process, and if it is found to be damaged or altered it undergoes cell death, either by apoptosis or necrosis, to eliminate the threat it cause to the organism’s survival.

Cellular processes Active transport and Passive transport - Movement

of molecules into and out of cells. Autophagy - The process whereby cells "eat" their own

internal components or microbial invaders. Adhesion - Holding together cells and tissues. Cell movement

- Chemotaxis, contraction, cilia and flagella. Cell signaling - Regulation of cell behavior by signals from

outside. Division - By which cells reproduce either by mitosis (to

produce clones of the parent cell) or Meiosis (to produce haploid gametes)

DNA repair - Cell death and cell senescence. Metabolism - Glycolysis, respiration, photosynthesis,

and chemosynthesis. Signalling - The process by which the activities in the cell

are regulated Transcription and mRNA splicing - Gene expression.

Techniques used to study cells Cell culture is the basic technique of growing cells in

a laboratory independent of an organism. Immunostaining, also known as immunohistochemistry,

is a specialized histological method used to localize proteins in cells or tissue slices.

Computational genomics is used to find patterns in genomic information

DNA microarrays identify changes in transcript levels between different experimental conditions.

Gene knockdown mutates a selected gene. In situ hybridization shows which cells are expressing a

particular RNA transcript. PCR can be used to determine how many copies of a

gene are present in a cell. Transfection introduces a new gene into a cell, usually

an expression construct

Purification of cells and their parts

Cell fractionation: Release of cellular organelles by disruption of cells. Separation of different organelles by centrifugation.

Flow cytometry Immunoprecipitation:

The binding of an antibody to a target protein Collection of the target protein through elution

Proteins extracted from cell membranes by detergents and salts or other kinds of chemicals.

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