chapter 6 cells

Chapter 6 Cells

web.jjay.cuny.edu

Video cells

• http://www.youtube.com/watch?v=1Z9pqST72is&feature=youtube_gdata_player

All cells

• The basic unit of structure and function of life, cells come from pre existing cells

• Cell membrane/plasma membrane• Cytosol/cytoplasm• Chromosomes with genes in the form of DNA• Ribosomes to make proteins using the DNA

instructions.

Before the “nut” nucleusProkaryotes

• DNA not in a membrane bound nucleus, nucleoid area, circular strand of DNA.

• Evolved first, combinations in symbiotic relationships may have formed eukaryotes.

• Ribosomes: different type from eukaryotes• Cell wall outside of membrane• May have flagella or fimbriae to move or attach.• Capsule: outer coating for protection/may be

disease causing

Prokaryotic cell

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Eukaryotic Cells True “nut”• Nucleus, nuclear membrane, nucleolus, chromatin• Cytoskeleton/microfilaments, microtubules,

intermediate filaments• Membrane bound organelles: ER, mitochondria,

Golgi app, lysosomes, peroxisome, • Generally much larger compared to prokaryotes.• Larger ribosomes• plant: Cell wall, chloroplast/ large central

vacuole,plasmodesmata• Animal: centrosome/centrioles

Basic eukaryotic animal cell

Functions of Organelles

• What would happen if one were missing?• Understand the relationship between

organelles and cell survival!

Compare the cell to a city!

The NUCLEUS

• (“mayor of city hall”)• The nucleus houses the majority of genetic

material of a cell. The nucleus is the “brain” of the cell and controls all activity within the cell. Using DNA as a blueprint

• (like the blueprints of a city) the nucleus directs the production of proteins.

nucleus

A nucleus with the DNA coiled into chromatin.     Electron microscope picture of a nucleus

RIBOSOMES (“lumber or brick yard”)

• The ribosomes carry out manual labor in the form of protein synthesis for the nucleus. They bring together mRNA (copies of the original DNA blueprints)and tRNA which carries the amino acids to assemble proteins.

• The proteins created are essential to the proper functioning of the cell. Think of proteins as machinery for cell functions much like electricity and plumbing are essential in a real city. For example, enzymes are a type of protein without which life could not exist.

RIBOSOMES

• The large and small subunits of ribosomal RNA translating an mRNA strand into a polypeptide chain

The ENDOPLASMIC RETICULUM (“highways and road systems”)

• There are two types of endoplasmic reticulum (within the cytoplasm) (ER) – Smooth ER and Rough ER. This extensive network makes up approximately one half of all membranous tissue of the cell and is the site of membrane and protein synthesis.

• Rough ER is named for the presence of ribosomes along its membrane and is the source of proteins and more membrane.

• Smooth ER lacks ribosomes and is responsible for lipid synthesis, metabolism of carbohydrates, storage of calcium and a variety of metabolic processes such as drug detoxification.

The ENDOPLASMIC RETICULUM (

• Can you tell the difference between the smooth and rough ER?

CYTOSKELETON (“steel girders”)

• The cytoskeleton makes up the internal framework, like the steel girders that are the framework for buildings in a city that gives each cell its distinctive shape and high level of organization. It is important for cell movement and cell division (mitosis).

• Microfilaments, microtubules and intermediate filaments compose the cytoskeleton

CYTOSKELETON

GOLGI APPARATUS (“post office”)

• From the ER to the golgi a series of flattened membranes called cisternae. They receive and then send off in vesicles materials that the cell produces. The products are often modified in the process. The golgi even makes some carbohydrates.

• The process even includes marking the vesicles with chemicals to guide them to their intended locations!

GOLGI APPARATUS (“post office”)

LYSOSOMES (“waste disposal and recycling”)

• The lysosomes are digestive sacs that can break down macromolecules in the cell using the process of hydrolysis. The digestion is carried out with lysosomal enzymes found in the lysosome.

VACUOLES and VESICLES (“warehouses, water towers or garbage dumps”)

• Think of these membrane sacs that have a variety of functions as containment units for anything in excess in a city. They can hold many substances from organic molecules to simple excess water. Plant cells have a central vacuole that is important in maintaining plant turgidity

Cell wall

• Cellulose along with other polysaccharides• Microfibrils• Plasmodesmata: connections between cell

walls of plant cells.

Animal cells extra cellular matrix ECM

• No cell walls but they do have fibers out side of the cell membrane.

• integrins: proteins built into the membrane provide a method for communication with the outside and the inside of the cell.

• This can even trigger a change in gene expression! What protein is being made!

Cell junctions• Plant junctions:• Plasmodesmata: these openings allow plant

cells to share cytosol and even proteins and RNA!

Animal: Tight: very close, water tight, in skin cellsDesmosomes: anchoring, some movement, in

muscle cellsGap Junctions: communicating junctions, like

pores, in heart tissue.

mitochondrion

• Double membrane• Site of cellular respiration• Matrix • Has its own DNA

chloroplast

• Double membrane• Has its own DNA• Stroma, grana,

thylokoids

chloroplast

Read page 122

• The cell is greater than the sum of its parts!!!!

• http://www.youtube.com/watch?v=o1GQyciJaTA&feature=youtube_gdata_player

• Biotechnology Video on the cell.