CELL STRUCTURE & FUNCTION

7.1 Life is Cellular

Discovery of the Cell England- In1665, Robert

Hooke viewed a thin slice of cork under a microscopeReminded him of a

monastery's tiny rooms, he

called them cells Holland- In 1674, Anton

van Leeuwenhoek observed microorganisms in pond water

Discovery of the Cell

1838 German botanist Matthias Schleiden concluded that all plants were made of cells

1939 German biologist Theodor Schwann stated that all animals were made of cells

Discovery of the Cell

In 17855, German physician Rudolf Virchow concluded that all cells must come from preexisting cells

The Cell Theory

All living things are composed of cells.

Cells are the basic unit of structure and function in living things.

New cells are produced from existing cells.

Exploring the Cell

Variety of shapes & sizesFrom tiny bacteria

(0.2 μm) to large amoeba (1,000 μm)

All are surrounded by a cell membrane and contain DNA

Prokaryotes & Eukaryotes Nucleus- large

membrane-enclosed structure that contains the cell’s genetic material (DNA)Prokaryotes- do not

contain nucleiEukaryotes- contain

nuclei

Prokaryotes

Prokaryotic cells are generally smaller, simpler, and single cellularThere are many exceptions to this

rule, but NONE of them have genetic material that is contained in a nucleus.○Example: BACTERIA

Prokaryotes Genetic material

not contained in the nucleus

Carry out every activity associated with living thingsGrow, reproduce,

respond to stimuli

Eukaryotes Eukaryotic cells

are larger, more complex, and can be single or multicellular.

Genetic material is separated into nucleus

Examples: Plants, animals, fungi, and protists

CELL STRUCTURE & FUNCTION

7.2 Eukaryotic Cell Structure

Comparing the Cell to a Factory

Organelles- “little organs”; specialized functions

Two Major Parts:NucleusCytoplasm- portion

of the cell outside the nucleus

Nucleus Control center;

“office” Nuclear envelope Chromatin- protein

bound DNA Chromosomes-

condensed chromatin

Nucleolus- assembly of ribosomes

Nucleus

The control center of the cell Contains most of the cell’s DNA DNA contains instructions for making

proteins and other important molecules. The nucleus is surrounded by the

nuclear envelope , composed of two membranes with thousands of pores allows messages from the nucleus to reach

the cytoplasm.

Nucleus

The granular material in the nucleus is called chromatin and consists of DNA bound to protein.

Most of the time, chromatin is spread throughout the nucleus. However, chromatin condenses to form chromosomes during cell division.

Nucleus

The small dense region in the nucleus is called the nucleolus and is the site where ribosomes begin to form.

Ribosomes Protein

synthesizing “machine”

Makes proteins using coded instructions from the nucleus

Found throughout the cytoplasm

Endoplasmic Reticulum

Internal membrane system; “transport”

Lipid components of the cell membrane are assembled

Rough ER- ribosomes on surface; produce proteins for export

Smooth ER- contains enzymes responsible for cell detox

Golgi Apparatus

A specialized stack like system of membranes

Modifies, sorts, and packages proteins made in the Rough ER

Like a “customization shop” preparing proteins for shipment

Lysosomes Recycles worn out

cellular products; “Clean Up Crew”

Small organelles filled with enzymes

Breaks down lipids, carbs, and proteins for use elsewhere in the cell

Vacuoles Saclike structures;

Cell “storage” Store materials

such as water, salts, proteins, and carbohydrates

Assists in maintaining homeostasis inside the cell

Mitochondria & Chloroplast

Produce energy for the cell; “powerhouse”

Mitochondria- convert chemical energy stored in food into compounds the cell can use

Chloroplast- capture energy from sunlight and transform it into chemical energy photosynthesis

Mitochondria and Chloroplast

Only organelles that contain their own DNA

Lynn Margulis proposed that these organelles descended from prokaryotes which took up residence within the eukaryotic cell.

Cytoskeleton

Supports the cell; maintains shape

Network of protein filaments

Also involved in movementMicrofilaments

○ Cilia○ Flagella

MicrotubulesCentrioles- aid in cell

division in animal cells

CELL STRUCTURE & FUNCTION

7.3 Cell Boundaries

The Cell Membrane

Regulates what enters and leaves the cell

Provides protection and support

Semipermeable

Made up of a double layered sheet called a lipid bilayer

Lipid Bilayer

Lipids are made up of 2 parts:1. Hydrophobic layer

2. Hydrophilic layer Contains proteins

throughout Carbohydrate

molecule chains attached to the proteins

Types of Transport

Passive Transport Does NOT require

energy Types:

1. Diffusion

2. Facilitated Diffusion

Active Transport DOES require

energy

Diffusion

Causes many substances to move across a cell membrane but does not require the cell to use energy

Solutions move from high concentration to low concentration

Diffusion

The process of diffusion continues until a state of equilibrium is reached in which the concentration is the same throughout the system.

Special Type of Diffusion: Osmosis The diffusion of water through a

selectively permeable membrane

Solutions

In a hypertonic solution, a cell will shrink as water moves out of the cell through osmosis.

In a hypotonic solution, a cell will expand as water moves into the cell

In an isotonic solution, the size of the cell will remain the same as an equal amount of water moves into and out of the cell.

Osmosis – Isotonic Solution

Osmosis – Hypotonic Solution

Osmosis – Hypotonic Solution

Osmosis – Hypertonic Solution

Osmosis – Hypertonic Solution

Osmosis

Facilitated Diffusion Molecules which cannot move through

the cell membrane on their own use a protein channel to move from high concentration to low concentration

Active Transport A process in which energy is required to

move a molecule from low concentration to high concentration. Energy requires ATP.

Active Transport - Endocytosis

The process of taking large amounts of material into the cell by means of infoldings, or pockets, of the cell membrane

Active Transport – Endocytosis: Phagocytosis

• A form of endocytosis in which large particles are taken in to the cell

Active Transport – Endocytosis: Pinocytosis In a process similar to endocytosis,

many cells take up liquid from the surrounding environment.

Tiny pockets form along the cell memebrane, fill with liquid, and pinch off to form vacuoles within the cell.

Active Transport - Exocytosis The removal of large amounts of

material from a cell

CELL STRUCTURE & FUNCTION

7.4 The Diversity of Cellular Life

Unicellular Organisms

Sometimes a cell IS an organism.

They do everything an organism would doGrowRespondTransform energyReproduce

Dominant form of life on Earth

Multicellular Organisms

Animals and PlantsCell Specialization-

cells develop in different ways to perform different tasks

Levels of Organization

In order of increasing complexityCellsTissuesOrgansOrgan Systems

Levels of Organization

Tissues- group of similar cells that perform a particular function

Types in Animals MuscleEpithelialNervousConnective

Levels of Organization

Organs- groups of tissues that work together to perform closely related functions

Levels of Organization Organ Systems- group of organs that work

together to perform a specific function