Cellular Structure and Organization

Miss. BurriesciOctober 2018

OLH

WHAT ARE THE 3 PARTS TO THE CELL THEORY AS STATED BY VIRCHOW????

Cell come from pre-existing cells.

All living things are COMPOSED of cells.

The cell is the BASIC functional and structural unit of life.

Prokaryotes & Eukaryotes▪All cells are surrounded by a thin flexible barrier called a plasma membrane.▪Cells fall into one of the two categories based on whether or not they contain a nucleus, which is a large membrane enclosed structure that contains genetic material in the form of DNA and controls many of the cells activities. ▪Note: Prokaryotes DO NOT enclose their DNA in nuclei.

…2 Categories of Cells

▪Eukaryotic:▪Membrane bound organelles▪Nucleus, Endoplasmic Reticulum, Golgi, Vesicles, Mitochondria, Chloroplasts

▪Prokaryotic:▪Circular chromosome (DNA)▪No membrane bound organelles

Prokaryotic Cell Features●Prokaryotic cell organization is a characteristic of the

kingdoms Eubacteria and Archaebacteria. Prokaryotic cells lack internal compartments.

●All prokaryotes have●plasma membrane●nucleoid region with DNA●cytoplasmic ribosomes

●Some prokaryotes have ●cell wall (made of Peptidoglycan, which Is a large single

polymer of amino acids and sugar)●outer membrane and capsule●photosynthetic membranes

Prokaryotic Cell Movement and Response to Stimuli

●Some prokaryotes have rotating cilia and flagella for movement.

●Pili are projections by which prokaryotic cells attach to one another or to environmental surfaces.

Eukaryotic Cell Features

●Eukaryotic cell organization is a characteristic of the other four kingdoms – Animalia, Protista, Plantae, Fungi.

●Eukaryotic cells have many membrane-enclosed compartments, including a nucleus containing DNA.

Animal/ Plant Eukaryotic Cell Organelles

Cytoplasm:▪The portion of the cell outside the nucleus.

▪Prokaryotic cells have a cytoplasm to, even though they do not contain a nucleus. ▪A fluid that fills the cell.

The Nucleus • Control Center of a cell.• Contains DNA.• Prokaryotic Cells lack nucleus, they do have DNA.• Surrounded by a double layered nuclear envelope.• The nucleus is studded with pores to allow materials

to pass in and out (RNA, etc.).• Chromosomes are found within the nucleus ( spread

out in the form of Chromatin, a complex of DNA bound to proteins).

• Nucleolus= is where the “assembly of ribosomes” begins.

Organelles that Store, Clean Up, and Support: ▪Vacuoles (large, saclike membrane enclosed structure) store materials like water, salts, proteins, and carbohydrates. ▪ In plant cells, there is one large central vacuole filled with liquid. ▪Vesicles are smaller membrane-enclosed structures that store and move materials between cell organelles, as well as to and from the cell surface. ▪Lysosomes (“The Clean-Up Crew”/ Remove “Junk”), are small organelles filled with enzymes to help break down lipids, carbohydrates, and proteins into small molecules that can be used by the rest of the cell. ▪They are involved in breaking down organelles that have over lived their usefulness.

Organelles that Store, Clean Up, and Support: Continued…

▪The Cytoskeleton= this is what gives eukaryotic cells their shape and internal organization by a network of protein filaments. (Helps cell to maintain shape and

it is involved in movement)

▪Microfilaments, are threadlike structures made up of a protein called Actin.

-Tough flexible framework that supports the cell. They can also help the cell move, such as helping amoebas and other cells crawl along surfaces. ▪Microtubules, are hollow structures made up of proteins called Tubulins. Critical role in maintaining cell shape. ▪Centrioles, are also formed from Tubulins. They are located near the nucleus and help organize cell division.

(Centrioles are NOT FOUND in plant cells)

▪Microtubules also help build projections from the cell surface such as cilia and flagella, which allows cells to swim through liquid.

Organelles that Build Proteins:▪ Ribosomes, are small particles of RNA and protein found throughout

the cytoplasm in all cells. ▪ Ribosomes synthesize (make) proteins by following coded instructions from

DNA.

▪Ribosomes are like “factory machines.”▪Endoplasmic Reticulum or ER, (internal membrane system) where lipid components of the cell membrane are assembled along with proteins and other materials.

▪Rough ER= synthesizes proteins for export (will be released or secreted for lysosomes), studded with ribosomes at the surface.

▪Smooth ER= ribosomes are not found on its surface. Synthesizes lipids and the detoxification of drugs.

EX. Liver cells contain large amounts of smooth ER. *Proteins receive their “address tags” here.

Organelles that Build Proteins▪Golgi Apparatus, (appears as a stack of flattened membranes) modifies, sorts, and packages proteins and other materials from the endoplasmic reticulum for storage in the cell or release outside the cell. ▪From the Golgi…. “packages” are “shipped” to their final destinations in or out of a cell.

Organelles that Capture and Release Energy▪Chloroplasts, (the biological equivalent's of solar power plants) capture energy from the sunlight and covert it into food that contains chemical energy in a process called Photosynthesis.

▪Inside the organelle are layered stacks of other membranes that contain a green pigment called Chlorophyll.

Organelles that Capture and Release Energy▪Mitochondria: convert the chemical energy stored in food into compounds that are more convenient for the cell to use.

FUN FACT: CHLOROPLASTS AND MITOCHONDRIA CONTAIN THEIR OWN GENETIC MATERIAL IN THE FORM OF SMALL-DNA MOLECULES. THIS OBSERVATION LED TO THE IDEA THAT THEY MAY BE DESCENDED FROM INDEPENDENT MICROORGANISMS…........................ENDOSYMBIOTIC THEORY (Cells living within Cells!!!!!)

Cell Boundaries▪Cell Wall, serves as a protective barrier that keeps a cell safe and secure. ▪Many cells, including prokaryotes, produce a cell membrane around them. ▪Many cells have a cell wall, in addition to a cell membrane. ▪The main function is to support, shape, and protect the cell. ▪Animal cells DO NOT have cell walls. ▪ Cell Walls lie outside the side membrane. ▪Most cell walls are porous, to allow water/oxygen/carbon dioxide/ and

other substances to pass through easily. ▪ Cell Walls are needed in plants in order for them to withstand gravity.

Cell Membranes:▪ All cells contains cell membranes, which are almost always made up of a

double layered sheet called a…Lipid Bilayer.

▪ Lipid Bilayer gives cell membranes a flexible structure that forms a strong barrier between the cell and its surroudings.

▪ The cell membrane regulates what enters adn leaves a cell and also protects and suppuorts a cell.

Fluid Mosaic Model:• Proteins molecules are embedded within the lipid bilayer of most cell

membranes. Because these proteins can “float” among the lipids, and because so many other kinds of molecules make up the cell membrane, scientists describe the cell membrane as a “fluid mosaic.”

-Selectively Permeable Membrane (Semipermeable membrane)= meaning that some substances can pass across the membrane and others cannot.