NOTES FOR BIOLOGY 1201

Section 001

Spring 2005

DR. STEVEN POMARICO

Prokaryotes vs. Eukaryotes 3.1.2

>>>>>An overview of “the cell”

---Prokaryotic versus Eukaryotic cells

---Nucleoid

---Cytoplasm

---Cytosol

---Organelle

Plant and Animal Cell Overview: The Basics - 3.1.3

---Plasma membrane

-Compartmental organization

The Nuclear Envelope: The Initial Tour - 3.1.5

Nuclear Function: Who’s in Charge? - 3.1.6

>>>>>The nucleus contains the cell’s genetic library

---Nucleus

---Nuclear envelope

---Chromatin

---Chromosomes

---Nucleolus

>>>>>Many cell organelles are connected through the endomembrane system

Endomembrane system

         -components include:

                   -Nuclear envelope

                   -Endoplasmic reticulum

                   -Golgi apparatus

                   -Lysosomes

                   -Vacuoles

All of the components are related either directly or indirectly

Cellular Function: Endoplasmic Reticulum - 3.2.1

>>>>>The endoplasmic reticulum manufactures membranes and performs other vital biosynthetic functions

---Endoplasmic reticulum (ER)

-Smooth ER

         Functions

                   1. Synthesis of lipids

                   2. Carbohydrate metabolism

                   3. Detoxification

                   4. Calcium storage

-Rough ER

         Functions

                   1. Manufacture of membranes

                   2. Synthesis of secretory proteins

                             A. Makes glycoproteins by attaching sugars to the proteins

---Glycoproteins

Cell Function: Golgi Apparatus - 3.2.2

>>>>>The Golgi apparatus finishes, sorts and ships many cell products

---Golgi apparatus

-Cis face and trans face

Food Vacuole Formation: The Role of the Lysosome - 3.2.3

>>>Lysosomes are digestive compartments

---Lysosomes

         Functions of lysosomes:

                   1. Intracellular digestion

                             ---Phagocytosis

                                       -Macrophages

                   2. Recycling of cellular material

                   3. Programmed cell destruction

Still More Vacuoles and Peroxisomes - 3.2.4

>>>>>Vacuoles have diverse functions in cell maintenance

---Vacuoles

Vacuoles (large) versus vesicles (smaller)

         Vacuole Types:

                   ---Food vacuole

                   ---Contractile vacuole

                   ---Central vacuole

                   ---Tonoplast

>>>>>Peroxisomes consume oxygen in metabolic functions

---Peroxisomes

Functions:

         1. Oxidation of molecules

                   A. Breakdown of fatty acids 

         2. Breakdown of peroxide (H₂O₂)

         3. Detoxification

                   Alcohol

>>>>>Mitochondria and chloroplasts are the main energy transformers of cells

General features:

         -Double membrane

         -Membranes are not part of the endomembrane system

         -Contain ribosomes and DNA

                   Make some but not all of their proteins (10-20%)

         -Are semi-autonomous

                   Can grow, move, change shape and reproduce

         -More permeable outer membrane

Mitochondria: Welcome Guests - 3.2.5

---Mitochondria

Features:

         -Size 1-10μm

         -Number per cell varies with metabolic activity

         -Outer membrane is highly permeable to small molecules but blocks passage                of proteins and other macromolecules

-Inner membrane is highly folded to increase surface area. The infolded structures are called cristae

         -Space between the outer and inner membranes is called the intermembrane             space

         -Space inside the inner membrane is called the mitochondrial matrix

---Plastids

Three types of plastids: Amyloplasts, Chromoplasts, and Chloroplasts

The Structure of a Chloroplast - 5.2.2

---Chloroplasts

Features:

         -Size 2.0-5.0 μm

         -Number per cell varies with metabolic activity

         -Outer membrane is highly permeable to small molecules but blocks passage                of proteins and other macromolecules

         -Inner membrane runs along the inside of the outer membrane creating a narrow                  intermembrane space

         -Space inside the inner membrane is called the stroma.

---Stroma

         -A third membrane system, the thylakoids, is found in the chloroplast stroma.

---Thylakoids

---Grana

---Thylakoid space

The Cytoskeleton: Basic Components - 3.3.1

>>>>>The cytoskeleton provides structural support and functions in cell motility.

---Cytoskeleton

General functions:

         -Mechanical support for the cell

         -Allows the cell to maintain shape and change shape

-Involved with organelle movement and cell movement by interacting with specialized proteins called motor molecules

General features:

-Constructed from at least three types of fibers: microtubules (thickest), microfilaments (thinnest), and intermediate filaments (in between size)

Cell Walls - 3.3.3

>>>>>Plant cells are surrounded by cell walls

Composed of cellulose fibers embedded in a matrix of other polysaccharides and proteins.

Development of the cell wall:

         -Young plant cell secrete a thin flexible primary cell wall

         -Between the primary cell walls of adjacent cells is the middle lamella that                    is composed of sticky polysaccharides that cement the cells together

-As the plant cells mature and stop growing they may add a hardening substance to the primary cell wall and/or secrete a secondary cell wall between

                             the primary cell wall and the plasma membrane.