A Tour of the Cell

What is a cell?

The cell is the fundamen

tal unit of life (for biology, as the atom is fundamental for chemistry). All organisms are made of cells --> basic units of structure and function. Each action of an organism begins at the cellular level.

What do biologists use to study cells?

To study cells, biologists use microscopes and the tools of biochemistry.

- light microscopes (LM) - uses visible light to illuminate the objects

- electron microscopes (EM) - uses beams of electrons instead of light

.. scanning electron microscope (EEM)- surface view

.. transmission electron microscope (TEM) - look inside

What is the difference bet

ween animal and plant cell?

- Plant cells have cell walls, a central vacuole, plasmodesmata and chloroplasts (animal cell x).

- Animal cells have Lysosomes, Centrosomes with centrioles and flagella (sometimes present in plan

t sperm)

Facts:

- The cell is fundamental to the living systems of biology as the atom is to chemistry.

- The light microscope offers

advantages in studying living cells (methods used in electron microscopy kill the cells).

- Larger organism do not generally have larger cells than smaller organisms - simply more cells.

- Improvements in microscopy that affect the parameters of magnification, resolution, and contrast have catalyzed progress in the study of cell structure.

- All cells are bounded by a plasma membrane.

Key terms:

cell = basic functional unit of all living things

lipid bilayer = double phospholipid membrane --> outer hydrophilic heads and hydrophobic tails pointing towards inside

organelles = bodies within the cytoplasm that serve to physically separate the various metabolic reactions that occur within the cells

nucleus = "brain" of the cell

ribosome = consisting of RNA

endoplasmic reticulum = stacks of flattened sacs involved in the production of various materials

golgi apparatus = group of flattened sacs arranged like a stack of bowls, functioning to modify and package proteins and lipids into vesicles

lyzosomes = vesicles from a golgi apparatus that contain digestive enzymes

mitochondria = organelles that carry out aerobic respiration

chloroplasts = organelles that carry out photosynthesis

flagella and cilia = structures that protrude from the cell membrane and make wavelike movements

Summary:

Although the cell is the smallest unit of life, it is by no means simple. The human body is made up of tens of trillions of cells, which have developed a highly synchronized set of components to carry out the processes that keep the organism alive, allow it to reproduce and adapt to changing environments.

Organelles are bodies within the cell cytoplasm that serve to physically separate the various metabolic reactions that occur within the cell. Some of them are : the nucleus, ribosomes, endoplasmic reticulum, golgu apparatus, lysosomes, peroxisomes, mitochondria, chloroplasts, microtubules, fagella and cilia, centrioles, cell walls, vacuoles and vesicles...

Extra:

animal cell (video)