Cellular System

Red Blood Cells

The adult human body contains 100 trillion cells

Cellular Structure

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What tool do we use to observe cells?

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Observing a Cell

Microscope History

Robert Hooke – English scientist; first to use the term “cell”; came from monk’s quarters

Anton von Leeuwenhook - Dutch scientist first to observe and describe microorganisms

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Microscope Characteristics Magnification - making image larger than it really is

Resolution - measure of clarity of an image

Good = clear crisp image

Poor = fuzzy image

Micrograph – the image produced by a microscope

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Types of Microscopes

Compound Light – uses two lenses; magnify up to 1,000 times, can view live specimens

Electron Microscope – magnify up to 200,000 times

-Used to look at cell structure or cell surfaces

Scanning Tunneling Microscope – able to view atoms, can view live specimens

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Transmission Electron Microscope

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Smallest unit of life is the cell

Cell Theory

- developed by 3 German scientists: Schleiden, Schwenn, and Virchow

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Cell Features

3 parts of Cell Theory

1) all living things are made of one or more cells

2) cells are the basic unit of structure and function in organisms

3) all cells arise from existing cells

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Why are cells so small?

Smaller = more efficient

Small cells can exchange substances more readily

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Surface area and cell size

Cell size is limited by the cell surface area

Cell size increases = surface-area-to-volume ratio decreases

When the volume of a cell increases, the surface area increase at a slower rate.

Surface area is important to cell growth because the cell may become too big to take in enough food and to remove enough wastes.

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Two types of cells

Prokaryotic & Eukaryotic

Only eukaryotic cells have membrane-bound organelles

Orgnaelles: structures that perform a specific function

All cells have the following:

Cell membrane, cytoplasm, cytoskeleton, ribosomes

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Chromosomes

Cilia or

Flagella

Cell Membrane

Ribosomeso

Cytoplasm

Cytoskeleton

Cell Wall(NO NUCLEUS)

Centrioles

Endoplasmic Reticulum

Golgi Complex

Lysosomes

Mitochondria

Nucleus

Peroxisomes

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Comparing Cells

small single celled organism that lacks a nucleus and other internal compartments (lacks membrane-bound organelles)

DNA is single, circular molecule

cell wall determines shape due to no internal skeleton

many use flagella for locomotion

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Prokaryotes (bacterium)

Examples of Prokaryotic Cells

Blue Green BacteriumE.Coli Bacterium

Salmonella Bacterium

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(plants, animals, fungi, protists)

Cell Membrane

* encloses the contents of a cell

* allows materials to enter and leave

cell

* selective permeability – allows

certain substances to pass thru

cell membrane

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Eukaryotes

Cell Membrane as a Barrier

phospholipid – phosphate group and two fatty acids Forms a lipid bilayer within a cell membrane phosphate group – polar heads that interacts with H20 fatty acids – non-polar tails

lipid bilayer non-polar tails form interior of membrane polar head form exterior

membrane proteins proteins and enzymes embedded in membrane polar and non-polar amino acids, which allow them to remain in membrane

different roles played:

cell-surface marker

receptor proteins

transport proteins

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Diagram of Lipid Bilayer

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Membrane Proteins

Lipid Bilayer

Outside of cell

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Diagram of Eukaryotic Cell

Cell Organelles: Structure that performs a specific function Found only in Eukaryotes

A. The Nucleus

controls most functions of the cell

nuclear membrane/ nuclear envelope: double membrane around the nucleus that has nuclear pores

heredity info coded as DNA in nucleus as strands called chromosomes

Identifies cell as Eukaryotic

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Ribosome and Endoplasmic Reticulum (ER)

B. ribosomes – where proteins are made

-attached to ER and others are free floating

C. ER – move proteins and other substances

thru the cell, maintains homeostasis

rough ER – ribosomes attached

smooth ER – lack ribosomes; make lipids

and breakdown toxic substances

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D. Golgi Apparatus – flatten, membrane-bound sacs that serve as packaging and distributing center of cell(warehouse of cell)

Produces vesicles filled with proteins

E. Lysosomes – contain cell’s digestive enzymes (Fig. 3.15 in book)

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Packing and Distributing Proteins

harvests energy from organic compounds to make ATP

outer and inner membrane

have specific mitochondrial DNA; different from nuclear DNA

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Mitochondria

Other Organelles

Cilia: short, hairlike structures that protrude from the surface of a cell

Packed in tight rows

Help in movement

Flagella: used for movement

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1. Cell Wall – support and maintain cell shape (cellulose)

2. Chloroplasts – use light energy to make carbs from CO2 and H20, photosynthesis

-have own DNA

3. Central Vacuole – stores water & nutrients; maintains rigidity of plant.

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Unique Features of Plant Cells

Anatomy of Animal Cell

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