Bio 101 Medgar Evers College Fall 2017 The Cell Bio 101 Medgar Evers College Fall 2017

The History of Eucaryotes They first appeared approximately 2 billion years ago. Evidence suggests evolution from procaryotic organisms by symbiosis. Organelles originated from procaryotic cells trapped inside them.

The Cell Theory All living things are made up of cells Cells are the functional units of life Cells are the structural units of life All cells come from previous cells

Prokaryote vs Eukaryote cell Primitive cells 1-10 µm in size Bacteria/ archaea No nucleus No membrane bound organelles Advanced cells 10- 100µm in size Found in Eukarya domain of life Nucleus Membrane bound organelles

3 Domains

External Structures Locomotor appendages function in motility Flagella, whip like structure function in motility cilia similar in overall structure to flagella, but shorter and more numerous function in motility, feeding and filtering.

External Structures Glycocalyx an outermost boundary that comes into direct contact with environment usually composed of polysaccharides functions in adherence, protection, and signal reception

External Boundary Structures Cell wall rigid, provides structural support and shape

External Boundary Structures Cytoplasmic (cell) membrane typical bilayer of phospholipids and proteins sterols confer stability serves as selectively permeable barrier in transport Eucaryotic cells also contain membrane-bound organelles that account for 60-80% of their volume.

Internal Structures Nucleus compact sphere, most prominent organelle of eucaryotic cell nuclear envelope composed of two parallel membranes separated by a narrow space and is perforated with pores contains chromosomes nucleolus – dark area for rRNA synthesis and ribosome assembly

Internal Structures Endoplasmic reticulum – two types: Rough endoplasmic reticulum (RER)– originates from the outer membrane of the nuclear envelope and extends in a continuous network through cytoplasm; rough due to ribosomes; proteins synthesized and shunted into the ER for packaging and transport; first step in secretory pathway Smooth endoplasmic reticulum (SER)– closed tubular network without ribosomes; functions in nutrient processing, synthesis and storage of lipids, etc.

Internal Structures Golgi apparatus consists of a stack of flattened sacs called cisternae closely associated with ER Transitional vesicles from the ER containing proteins go to the Golgi apparatus for modification and maturation. Condensing vesicles transport proteins to organelles or secretory proteins to the outside.

Internal Structures Lysosomes vesicles containing enzymes that originate from Golgi apparatus involved in intracellular digestion of food particles and in protection against invading microbes

Internal Structures Mitochondria consists of an outer membrane and an inner membrane with folds called cristae Cristae hold the enzymes and electron carriers of aerobic respiration. divide independently of cell contain DNA and procaryotic ribosomes function in energy production

Internal Structures Chloroplast found in algae and plant cells outer membrane covers inner membrane folded into sacs, thylakoids, stacked into grana larger than mitochondria contain photosynthetic pigments convert the energy of sunlight into chemical energy through photosynthesis primary producers of organic nutrients for other organisms

Internal Structures Ribosomes composed of rRNA and proteins 40S and 60S subunits form 80S ribosomes larger than procaryotic ribosomes function in protein synthesis

Internal Structures Cytoskeleton flexible framework of proteins, microfilaments and microtubules form network throughout cytoplasm involved in movement of cytoplasm, amoeboid movement, transport, and structural support

Vacuoles Membrane bound structures that store food, water, or waste.

Centrioles Cylindrical shaped organelles involved in cell division.

Differences between a plant and animal cell 1- Plant cells have a cell wall 2- Plant cells are rectangular in shape 3- Plant cells have no centrioles 4- Plant cells have chloroplast 5- plant cells have a central vacuole.

Difference between plant and animal cell Plant cells have a cell wall 2- Plant cells are rectangular in shape 3- Plant cells have no centrioles 4- Plant cells have chloroplast 5- plant cells have a central vacuole.