Cytology The study of cells

1) Procaryotic 2) Eucaryotic Cell Types 1) Procaryotic 2) Eucaryotic

Procaryotic Cells Cells lack a true nucleus Cells have only non-membrane bound organelles Bacteria and some algae

Eucaryotic Cells Cells have a true nuclues Cells have membrane bound organelles Most protists All fungi, plants, animals, and humans

1) Boundary 2) Cytoplasm 3) Nucleus Cellular Structures 1) Boundary 2) Cytoplasm 3) Nucleus

Cellular Boundaries Plasma membrane Cell wall Middle lamella Capsule / sheath / slime coat

Plasma membrane The outermost boundary of all cells Semi-permeable Phospholipid bilayer Proteins are embedded within transportation cell recognition cell adhesion

Plasma membrane

Laminin video clip by louie giglio

Cell wall Rigid structure surrounding some cells Porous all procaryotes plants, algae, fungi, and protozoans Porous Composed of cellulose or chitin

Middle lamella Layer between two adjacent cell walls Acts as a lubricant

Capsule / Sheath / Slime coat A cellular secretion of polysaccharides Surrounds unicellular or colonial organisms Protective Attackers must first dissolve the capsule or penetrate it

Cytoplasmic Organelles Cytoplasmic matrix Ribosomes Endoplasmic reticulum Mitochondria Plastids Golgi body Lysosomes Vacuoles Centrioles Flagellum Cilia

Cytoplasmic Matrix (aka: the cytoplasm) Located in all types of cells A semi-solid watery substance in which all other organelles are suspended Think “jello salad” Provides structure to the cell thanks to its cytoskeleton Cytoplasmic streaming – contents are always moving

Ribosome Located in all types of cells Mass of proteins and RNA Function: protein synthesis

Endoplasmic Reticulum Seen only in eukaryotic cells Folds of cellular membranes Continuous with both the plasma membrane and the nuclear membrane Functions: Provide flexible but structural shape Synthesis of proteins, lipids, & polysaccharides Movement of substances throughout the cell

Types of ER’s

Mitochondria Seen only in eukaryotic cells A double-membrane bound bean shape structure Inner membrane is folded to form cristae Function: cellular respiration Quantity is dependent on the activity level of the cell

Mitochondria

Plastids Seen only in plants and algae A double-membrane bound structure Function: synthesis and storage of polysaccharides

Types of Plastids Chromoplasts Contains the pigments used in synthesizing polysaccharides Given specific names based on the type of pigment in the chromoplast Most important chromoplast: the chloroplast (green pigment)

Chloroplast Inner membrane is folded to form the thylakoid Stack of thylakoids is called a grana Fluid within the chloroplast is called stroma

Types of Plastids Leucoplasts Colorless structure Function: a storehouse of starch Most numerous in the fleshy, storage areas of plants

Golgi body Seen only in eukaryotic cells A flat, curved, membrane structure Function: Synthesizing polysaccharides Final modifications of proteins & lipids for their final destination

Lysosome Seen only in eukaryotic cells Small, membrane bound spherical structure Contains digestive enzymes Function: digestion of old, used organelles digestion of invading cells

Vacuoles Seen only in eukaryotic cells Function: storage 4 types of vacuoles Phagocytic Pinocytic Waste Contractile

Types of Vacuoles Phagocytic Pinocytic Waste Storage of food Formed by phagocytosis Pinocytic Storage of water Formed by pinocytosis Waste Storage of nondigestible material Fuses with the plasma membrane to release material

Types of Vacuoles Contractile vacuole Found in unicellular organisms that live in a freshwater environment Collects excess water and pushes the water back out of the cell

Centriole Seen only in eukaryotic cells, except plants 2 cylinders occurring at right angles to each other Always located near the nucleus Function: cell division

Flagellum Located in all types of cells Long, tubular extension of the cytoskeleton within the cytoplasm Small quantity: usually have 1 – 4 flagella on a cell Function: locomotion of the cell

Cilia Located in all types of cells Short extensions of the cytoskeleton Usually covers the entire cell or a large section of a cell Function: locomotion of the cell or movement of substances within an organism

Internal Structure of Cilia & Flagella Both have the same internal structures Both structures have been used to disprove evolution Irreducibly complex

Nucleus (the control center of the cell) Nuclear envelope Chromatin material Nucleolus

Nuclear Envelope Seen only in eukaryotic cells Porous Phospholipid bilayer Continuous with the endoplasmic reticulum

Chromatin Material Seen in all types of cells Long, thin strands consisting of DNA and proteins Function: codes for the information needed for protein synthesis DNA permits activity of a cell, but it does not decide what the cell is capable of doing DNA was programmed by God at creation

Nucleolus An area with a large concentration of RNA (a substance similar to DNA)

Review of Cellular Structures