CELLS

…a sense of scale…..

Single-cellular OrganismMade of just one cell

Multi-celluar OrganismMade of many cells working together

Cell Types

• There are two major types of cells– Prokaryotic Cells

• Pro=Before• Karyon=Kernel or nucleus

– Eukaryotic Cells• Eu=New• Karyon=Kernel or nucleus

Cell Types

Prokaryote• Smaller• Less Complex• No nucleus• No organelles with

membranes• Bacteria

Eukaryote• Larger• More Complex• Has a nucleus• Organelles with

membranes• Plants, Animals,

Fungi, Protists

Discovery of Cells

Hans and Zacharias Janssen (1590)

• Made the First compound light microscope

Robert Hooke (1663)• Looked at a

piece of cork and called what he saw “cells”

Anton van Leeuwenhoek (1674)

• First to observe living cells

Theodor Schwann (1838)

• All animals are made of cells

Matthias Schlieden(1838)

• All plants are made of cells

Together they said all living things are made of cells

Rudolf Virchow (1855)

• Stated that Cells can only come from pre-existing cells

Cell Theory1. All organisms are composed of

one or more cells.2. The cell is the basic unit of

structure and organization of organisms.

3. All cells come from pre-existing cells.

Cell Structure

Organelles: structures inside cells that are specializedto perform specific tasks

(eukaryotic) cells are divided into 2 major parts: the nucleus & the cytoplasm (everything outside the nucleus)

Nucleus: contains almost all the cells’ DNA (the instructions for making the molecules of life)

Nuclear Envelope: the membrane surrounding the nucleus

Nuclear Pores: portals for materials to go in & out of the nucleus

Nucleolus: dense region of nucleus (which is made of RNA and protein) where ribosomesribosomes are made

Chromatin: strands of DNA bound to protein-condensesinto compact Chromosomes only when the cell divides

Ribosomes: the cellular “factories” that assemble

proteins

Endoplasmic Reticulum: where membranes & othercell “products” are assembled Rough ER- contains ribosomes / Smooth ER- no ribosomes

Golgi Apparatus: modifies, sorts, & “packages” proteinsmade in the ER for storage in the cell or “export”

Products get “shipped” from the ER & the Golgi apparatus in Transport Vesicles

Lysosomes: organelles filled with enzymesthat break down food molecules into smallermolecules that the cell can use

Lysosomes are important in developing embryos to “kill” off unneeded cells by breakingopen & spilling their contents inside cells

Lysosomes also break down old, worn-out cells, which is

why they are called the “suicide sacks” of the cell.

Vacuoles: saclikestructures that store materials for the cell (like H2O)

…the pressurecreated bywater in a plant’s central vacuolehelps keep plantsupright

Mitochondria: convert the chemical energy in foodinto compounds that are easier for the cell to use

Mitochondria have their own DNA. Another

interesting fact is that you inherit them ONLY

from your mother!

Chloroplasts: use energy from sunlight to convert H2O& CO2 into glucose (& O2) by photosynthesis

Cytoskeleton: a network of protein filamentsthat helps give a cell its shape.

There are 3 main types of fibers in the cyto-skeleton:

1)Microfilaments: made of the protein actin, they help cells change shape & help muscles contract

2) Intermediate Filaments: have ropelike structure-function to resist tension & stretching & anchoring certain organelles. These are made of various types of proteins.

3) Microtubules: straight, hollowtubes made of protein tubulin.-reinforce cell shape-act as tracks along which some organelles move-build cilia & flagella

Your white blood cells can “crawl” around bythe assembling & disassembling of microfilaments

bacteria

Cilia & Flagella: Both are arrangements of microtubules extending from some cells,either to move the cell or move things around the cell

Cilia are generallyshorter & morenumerous thanflagella

Compare and ContrastPlant cells & Animal Cells:

Cytoplasm

Cell Membrane

LARGEvacuoles

Chloroplast

Cell Wall

Rectangleshaped

SmallVacuoles or

NONE.

*Centrioles &Lysosomes

Roundshaped

Nucleus &Nuclear

Membrane

Plant Cells Animal Cells