Chapter 4 A tour of the cell

Cell Theory u All living matter is composed of one or more cells. u The cell is the structural and functional unit of life.

Cell Theory u “Omnis cellula e cellula” u All cells are from other cells.

Types of Cells u Prokaryotic - lack a nucleus and other membrane bound structures. u Eukaryotic - have a nucleus and other membrane bound structures.

Both Have: u Membrane u Cytosol u Ribosomes (but the size is different)

ProkaryoticEukaryotic Nucleus

Prokaryotes u Bacteria u Came first in evolution u Less complex u Have cell wall but different than plants

Eukaryotic u Protists, Plants, Fungi, Animals u More complex

Animal Cell

Plant Cell

Organelle u Term means "small organ” Formed body in a cell with a specialized function. u Important in organizational structure of cells.

Organelles - function u Way to form compartments in cells to separate chemical reactions. u Keeps various enzymes separated in space.

Plant vs Animal Cell u Plants u Have a large central vacuole to hold water u Contain chloroplasts u Have cell wall made of cellulose

Animals u Have centrioles u Have lysosomes u Have flagella

Nucleus u Most conspicuous organelle. u usually spherical, but can be lobed or irregular in shape.

Structure u Nuclear membrane u Nuclear pores u Nucleolus u Chromatin

Nuclear Membrane u Double membrane Nuclear Pores u Allow things in and out of nucleus u Ex. mRNA during transcription

Nucleolus u per nucleus. u Storage area for ribosomes. u Synthesizes rRNA

Chromatin u Chrom: colored u - tin: threads u DNA and Protein in a “loose” format. Will form the cell’s chromosomes.

Nucleus - Function u Contains the genetic instructions to make proteins and more DNA

Ribosomes u Structure: 2 subunits made of protein and rRNA. No membrane. u Function: protein synthesis. u Site of translation

Endoplasmic Reticulum u Folded sheets or tubes of membranes. u Membrane is continuous with the nuclear membrane

Types of ER u Smooth ER: no ribosomes. u Used for lipid synthesis, carbohydrate storage, detoxification of poisons. u Rough ER: with ribosomes. u Makes secretory proteins.

Function of Golgi Bodies u Processing - modification of ER products (lipids, carbs). u Distribution - packaging of ER products for transport.

Vesicles u Small sacs of membranes that bud off the Golgi Body. u Transportation vehicle for the modified ER products.

Lysosome u Structure: Single membrane. u Made from the Golgi apparatus.

Function u Breakdown and degradation of cellular materials. u Contains enzymes for fats, proteins, polysaccharides, and nucleic acids. u Over 40 types known.

Vacuoles u Structure - single membrane, usually larger than the Golgi vesicles. u Function – store water, and sometimes other molecules

Plants u Large single vacuole when mature making up to 90% of the cell's volume.

Mitochondria u Structure: 2 membranes. The inner membrane has more surface area than the outer membrane. u Matrix: inner space. u Intermembrane space: area between the membranes.

Function u Cell Respiration - the release of energy from food. u Major location of ATP generation. u “Powerhouse” of the cell.

Chloroplasts u Structure - two outer membranes. u Complex internal membrane. u Fluid-like stroma is around the internal membranes.

Function u Photosynthesis - the use of light energy to make food.

Cytoskeleton u Network of rods and filaments in the cytoplasm.

Functions u Cell structure and shape. u Cell movement. u Cell division - helps build cell walls and move the chromosomes apart.

Flagella u Made of the same components as part of the cytoskeleton u Helps cell move through body

Centrioles u Usually one pair per cell, located close to the nucleus. u Found in animal cells. u Help in cell division.

Cell Wall u Nonliving jacket that surrounds some cells. u Found in: u Plants u Prokaryotes u Fungi u Some Protists

Cell Walls u Function as the cell's exoskeleton for support and protection.