Biologia

The cell

Development of the Cell Theory
• Early observations:
– Robert Hooke, English, saw microscopic “cells” in thin
pieces of cork in 1665.
– Antonie van Leeuwenhoek saw microscopic bloodcells,
sperm and “animalcules” in the late 1600s.
– Theodor Schwann in 1839 stated that cells are the
elementary particles of both plants and animals.
– Mattias Scheleiden in the mid 1800s statedthat cells are
the absolutely indispensable fundamental basis of life.
– Rudolf Virchow in the late 1850s predicted that cells come
from cells.
Modern Cell Theory has three principles:
– 1. Everyliving organism is made up of one or
more cells.
– 2. Cells are the smallest functional units of life.
– 3. All cells arise from pre-existing cells.
• All cells have at least three components:
–Plasma cell membrane, double layer of
phospholipids
– Genetic material (DNA). Hereditary blueprint
– Cytoplasm.
Cell
It is the smallest functional unit of life.
Characteristics of living things.* They are complex and organized.
* They use the energy of the sun and acquire and convert nutrient molecules.
* They are homeostasts (They stay the same)
* Perceive and respondenvironmental stimuli.
* They reproduce
* Their population can evolve.
Types of cells:
1. Prokaryot: cells lack a membrane-bound or true nucleus, are small in size and lack most cellularorganells. Earliest cells to evolve. Asexual reproduction

2. Eukaryotic: cells have a membrane-bound or true nucleus, are larger in size and have cellular organelles. Two types: Animal and PlantsCytoplasm contains many types of membranebound organelles within a fluid matrix (the cytosol).

Have cytoplasmic cytoskeleton: network of protein fibers providing shape and organization.

Almostall eukaryotic cells have
these organelles:
–Nucleus
–Endoplasmic Reticulum (ER)
–Golgi Complexes
–Lysosomes
–Mitochondria
–Plasmatic Membrane

NUCLEUS
• Control center.
• Parts of nucleus:...