FUNCTIONS OF CELL STRUCTURES & ORGANELLES

THE CELL AS AN EFFICIENT,

OPEN SYSTEM

PHOTOMICROGRAPH

* A photograph taken through a microscope

* Each dark spot in the cells in the photomicrograph is the nucleus of the individual cells. The nucleus is just one of the organelles of a cell that work to carry out the life processes of the cell

THE CELL AS AN EFFICIENT,

OPEN SYSTEM

OPEN SYSTEM

* Any system that exchanges both matter and energy with its surroundings

* A perfect example of an open system is a living organism such as a human being. We actively interact with our environment, which results in changes to both the environment and us. For example, we eat to acquire energy. We are subject to the sun's radiation and the climate of our planet

THE CELL AS AN EFFICIENT,

OPEN SYSTEM

CELL MEMBRANE

* A protective barrier that surrounds the cell & allows the transport of nutrients into the cell & wastes out the cell 

* The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates the interior of all cells from the outside environment (the extracellular space) which protects the cell from its environment.

THE CELL AS AN EFFICIENT,

OPEN SYSTEM

CELL WALL

* A rigid, protective layer around the cell in plants, bacteria & some protists

*Protists are a diverse collection of organisms. While exceptions exist, they are primarily microscopic and unicellular, or made up of a single cell. The cells of protists are highly organized with a nucleus and specialized cellular machinery called organelles 

THE CELL AS AN EFFICIENT,

OPEN SYSTEM

CHLOROPHYLL

* A green pigment that makes photosynthesis possible

*Chlorophyll is a green pigment found in plants. Plants use chlorophyll and light to make food. People use chlorophyll as medicine. 

THE CELL AS AN EFFICIENT,

OPEN SYSTEM

CHLOROPLAST

* An organelle found in plants & some protists that contains chlorophyll & is the site of photosynthesis

* Are organelles found in plant cells and eukaryotic algae that conduct photosynthesis. Chloroplasts absorb sunlight and use it in conjunction with water and carbon dioxide gas to produce food for the plant.

THE CELL AS AN EFFICIENT,

OPEN SYSTEM

CYTOPLASM

* A gel-like substance inside the cell membrane in which the organelles are suspended 

* Is a thick solution that fills each cell and is enclosed by the cell membrane. It is mainly composed of water, salts, and proteins

THE CELL AS AN EFFICIENT,

OPEN SYSTEM

CYTOPLASMIC STREAMING

* The distribution of material within a cell through the circular flow of cytoplasm

* Is a movement of cytoplasm in various organisms including bacteria, higher plants, and animals. Cytoplasmic streaming assists in the delivery of nutrients, metabolites, organelles, and other materials to all parts of the cell

THE CELL AS AN EFFICIENT,

OPEN SYSTEM

ENDOPLASMIC RETICULUM (ER)

* A network of membranes tubes that branch out from the nuclear envelope & circulate materials throughout the cell

* A continuous membrane system that forms a series of flattened sacs within the cytoplasm of eukaryotic cells and serves multiple functions, being important particularly in the synthesis, folding, modification, and transport of proteins 

THE CELL AS AN EFFICIENT,

OPEN SYSTEM

GOLGI APPARATUS

* A flat stack of membranes that receive, modify & transport products of the endoplasmic reticulum throughout the cell

* A major organelle in most eukaryotic cells is the structure of membrane-bound sacs called the Golgi apparatus. It acts to process and package the macromolecules such as proteins and lipids that are synthesized by the cell

THE CELL AS AN EFFICIENT,

OPEN SYSTEM

LYSOSOME

* An organelle containing enzymes that digest food, destroy bacteria & break down damaged organelles in cells

* Is a membrane-bound cell organelle that contains digestive enzymes. Lysosomes are involved with various cell processes. They break down excess or worn-out cell parts. They may be used to destroy invading viruses and bacteria

THE CELL AS AN EFFICIENT,

OPEN SYSTEM

NUCLEAR ENVELOPE (NE)

*  A double-layered membrane that separates the nuclear contents from the cytoplasm

* Is a highly regulated membrane barrier that separates the nucleus from the cytoplasm in eukaryotic cells. It contains a large number of different proteins that have been implicated in chromatin organization and gene regulation

THE CELL AS AN EFFICIENT,

OPEN SYSTEM

NUCLEUS

* The organelle that contains the genetic material of the cell & directs all cell activities

* Is an organelle found in eukaryotic cells. Inside its fully enclosed nuclear membrane, it contains the majority of the cell's genetic material. This material is organized as DNA molecules, along with a variety of proteins, to form chromosomes

THE CELL AS AN EFFICIENT,

OPEN SYSTEM

PHOSPHOLIPID BILAYER

* The double layer of outward-facing phosphates & inward-facing lipids that form a cell membrane

* Phospholipid bilayers are critical components of cell membranes. The lipid bilayer acts as a barrier to the passage of molecules and ions into and out of the cell. However, an important function of the cell membrane is to allow selective passage of certain substances into and out of cells

THE CELL AS AN EFFICIENT,

OPEN SYSTEM

RIBOSOME

* An organelle in the cell that is the site of protein synthesis

* Ribosomes are a cell structure that makes protein. Protein is needed for many cell functions such as repairing damage or directing chemical processes. Ribosomes can be found floating within the cytoplasm or attached to the endoplasmic reticulum

THE CELL AS AN EFFICIENT,

OPEN SYSTEM

VACUOLE

* A membrane-enclosed sac in a cell that serves to store nutrients, products of secretion or fats

* Vacuoles are storage bubbles found in cells. They are found in both animal and plant cells but are much larger in plant cells. Vacuoles might store food or any variety of nutrients a cell might need to survive. They can even store waste products so the rest of the cell is protected from contamination

THE CELL AS AN EFFICIENT,

OPEN SYSTEM

VESICLE

* A membrane-enclosed sac that transports materials in a cell; similar to vacuole

* Is a structure within or outside a cell, consisting of liquid or cytoplasm enclosed by a lipid bilayer. Vesicles form naturally during the processes of secretion (exocytosis), uptake (endocytosis) and transport of materials within the plasma membrane

THE CELL AS AN EFFICIENT,

OPEN SYSTEM

MITOCHONDRIA

* Are rod-like structures where cellular respiration takes place

* Mitochondrion, membrane-bound organelle found in the cytoplasm of almost all eukaryotic cells (cells with clearly defined nuclei), the primary function of which is to generate large quantities of energy in the form of adenosine triphosphate (ATP)