By: Jordyn

CHAPTER 3 REVIEW

Robert Hooke was the fi rst to describe cells, He used an early light microscope to examine dried cork. When he did this he saw thousands of tiny empty chambers which then later called them cells.

Research over the next 175 years led to the cell theory, the concept that cells are the fundamental parts of all plant and animal tissues. Cells are the building blocks of all plants and animals. Cells are produced by the division of preexisting cells. Cells are the smallest units that perform all vital

physiological functions Each cell maintains homeostasis at the cellular level Homeostasis at the tissue, organ, system, and individual

level reflects the combined and coordinated actions of many cells.

BASIC CONCEPTS OF CELL THEORY

Our cell floats in a watery medium known as the extracellular fluid.

It basically holds the rest of the fluid that the cell can’t

The cell membrane separates the contents or cytoplasm from the fluid. The cytoplasm then can be further subdivided into a fluid, the cytosol, and intracellular structures collectively known as organelles.

The subdivisions of the extracellular fluid are: Tissue fluid Interstitial

FLUID CONTENTS OF THE CELL

The cell membrane also called the plasma membrane and in which it forms the outer boundary of the cell.

The cell membrane is called a phospholipid bi-layer because they form two distinct layers.

The main functions of the membrane are isolation from the outside environment, protection, sensitivity, and organization. The major components of the cell membrane are:

Phospholipids Proteins Glycolipids Cholesterol

THE CELL MEMBRANE

Cells in the body work together to maintain homeostasis at the tissue, organ, and system levels. The essential communication and coordination activities involve the cell membrane which forms the interface between each cell and its surroundings.

The cell membrane regulates the dynamic exchange between the intracellular and extracellular fluids.

INTERACTIONS WITH ITS ENVIRONMENT

Cytoskeleton- Strength, movement of cellular structures and materials.

Microvilli- Absorption of extracellular materials.

Centriole- Movement of chromosomes during cell division.

Cilia- Movement of materials over surface

Ribosome- Protein synthesis

NONMEMBRANOUS ORGANELLES

Mitochondria – about 95 percent of the energy needed to keep a cell alive.

Nucleus- control of metabolism, storage and processing of genetic information.

Endoplasmic reticulum- Secretory protein synthesis, lipid, and carbohydrate synthesis.

Golgi Apparatus – Storage, alternation, and packing of the secretory products and lysosomes.

Lysosomes- intracellular removal of damaged organelles or of pathogens.

Peroxisomes- Neutralization of toxic compounds.

MEMBRANOUS ORGANELLES

The sun is basically the main component in giving the cell enough fuel to power all of the functions dealing with the cell.

Not only does it get power from the sun it gets that and energy from the mitochondria.

The mitochondria has small organelles that have an unusual double membrane.

With the ability to use both of the energizers, it gives all the power and energy to fuel all of the functions of the cell.

HOW THEY OBTAIN ENERGY

The nucleus is the control center for cellular operations, most all cells have a single nucleus skeletal muscle cells have some exceptions.

A nuclear envelope surrounds the nucleus and separates it from the cytosol. It is double membrane containing a narrow preinuclear space. Chemical communication between the nucleus and cytosol which occurs through nuclear pores.

The term nucleoplasm refers to fluid contents of the nucleus. It contains ions, enzymes, RNA, and DNA nucleotides, proteins, and small amounts of RNA and DNA.

THE ROLE OF THE NUCLEUS

The G1 phase occurs during interphase. The cell is doing its everyday job, there are only two chromosomes each one has one molecule of DNA.

During S phase the DNA duplicates, now the chromosomes have two molecules of DNA.

In G2 phase the cell carries out many processes that are necessary for mitosis to begin.

Mitosis is the stage when the cells DNA gets divided into two separate nuclei's.

In Mitosis there are four stages: Prophase, Metaphase, anaphase, and telophase.

Cytokinesis is a separate process from the division of mitosis, during this the two daughter cells start forming.

At the end of the cycle, the daughter cells are formed. They are smaller than there parents but are genetically daughter cells.

THE LIFE CYCLE/HOW THE CELL DIVIDES

The transmembrane potential of living cells are very small.

Two factors, one passive and one active, interact to create and maintain the transmembrane potential.

The passive factor is that the membrane permeability for sodium and potassium are quite diff erent potassium ions can diff use out of the cell through potassium channels faster than sodium channels.

The active factor is the presence of the sodium potassium exchange pump in the membrane surface.

The transmembrane potential is characteristic of all living cells because it results from the active and passive properties of their cell membranes.

TRANSMEMBRANE POTENTIAL

Most cells in the body are fi rmly attached to other cells or to extracellular protein fi bers. The attachments occur at cell junctions that are not involved in membrane fl ow.

There are four types of cell junctions: Gap Junctions– the two cells are held together by the interlocking of

membrane proteins.

Tight Junctions- there is a partial fusion of the lipid portions of the two cell membranes.

Intermediate Junctions- the opposing cell membranes while remaining distinct are held together by a thick layer of proteoglycans.

Desmosomes- there is a very thin proteoglycan layer between the opposing cell membranes reinforced by a network of intermediate fi laments that lock the two cells together.

HOW ATTACHMENTS AFFECT BODY TISSUES