The Cell

Robert Hooke

1665—observed cork under a microscope

Named the units “cells”

Reminded him of tiny rooms in a jail or monastery

More Contributions

Henry Dutrochet—1824 all living things were comprised of cells

Robert Brown—1831 named “nucleus”

Felix Dujardin—observed the jelly-like fluid in cells and called it protoplasm—now is called protoplasm, cytoplasm, or cytosol

Matthias Scheiden

1838—observed and proposed that all plants and plant parts are made up of cells

Theodor Schwann

1839—observed and proposed that all animals and animal parts are made up of cells

Rudolf Virchow

1858—stated that all cells come from the division of preexisting cells

Summary is known as The Cell Theory

The Cell Theory

1. All living things ( organisms ) are made of one or more cells.

2. The cell is the basic unit of life ( it is the basic structure and carries out the basic functions of all organisms).

3. All new cells come from preexisting cells.

Two Basic Cell Types:

1. Prokaryotes:• Smaller and

simpler• Have cell

membranes and cytoplasm

• No nuclei or other membrane bound organelles

• Bacteria

Two Basic Cell Types:

2. Eukaryotes:• More complex with

specialized parts• Have cell

membranes, cytoplasm, nuclei, and membrane-bound organelles

• ALL plants, animals, fungi, some microorganisms

Cell Structures:

Cell Wall—protects and supports the cell Found in plants, fungi, and nearly all

prokaryotes Plant cell walls made of cellulose Rigid layer outside the cell membrane

Cell Structures

Nucleus—controls most cell processes and contains the hereditary information of DNA

“control center of the cell” Transmits hereditary information Synthesizes ribosomes

Nuclear Structure

1. Chromatin—granular material within the nucleus consisting of DNA bound to proteins

2. Chromosomes—condensed chromatin that forms during cell division—carries genetic information

3. Nucleolus—small, dense regions where the assembly of ribosomes begin

4. Nuclear envelope—double-membrane layer that surrounds the nucleus

Cell Structures

Cytoskeleton—network of protein filaments that helps the cell maintain its shape; also involved in many forms of cell movement

Made of: Microtubules Microfilaments

Cytoskeleton

Microtubules Tubes of protein that

maintain cell shape and can serve as “tracks” along which organelles are moved

Form cilia and flagella in some cells

Form bundles called spindle fibers during cell division

Microfilaments Long, thin filaments

that function in movement an support of the cell

Threads made of the protein actin

Can play a role in the contraction of muscle cells

Cytoskeleton

Cell Structures

ALL cells have a cell membrane and cytoplasm

Cell membrane—regulates what enters and leaves the cell, holds cell together, made of lipids and proteins

Cytoplasm—fluidlike material between the nucleus and cell membrane. The site of chemical reactions and location of organelles

Organelles in the Cytoplasm

1. Ribosome2. Endoplasmic

Reticulum3. Golgi apparatus4. Lysosomes5. Vacuoles6. Chloroplasts7. Mitochondria

Ribosomes Produce proteins following coded

instructions that come from the nucleus

Tiny knob-like organelle—can be found attached to Endoplasmic Reticulum or free

Endoplasmic Reticulum

Organelle in which components of cell membrane are assembled and some proteins are modified

Series of canals or channels

Transportation between cytoplasm and nucleus

1. Rough ER—has attached ribosomes.

free ribosomes are not attached to a membrane

2. Smooth ER—no ribosomes on its surface

contains specialized enzymes

Golgi apparatus

Stack of flattened membranes in the cell in which enzymes attach carbohydrates and lipids to proteins

Storage and packaging of chemicals, helps make proteins

Lysosomes Small organelles filled with digestive

enzymes Digests large particles: “ suicide” sac

Breaks down lipids, carbohydrates, and proteins into particles that can be used by the rest of the cell

Helps break down old ( retired ) organelles

Vacuole

Saclike structure in which cells store materials such as water, salts, proteins, and carbohydrates

Fluid-filled membrane bound organelle In plant cells, single, larger and fluid-

filled In animal cells, may be called vesicles

Chloroplasts

Use the energy from sunlight to make energy-rich molecules during photosynthesis

Has flattened sacs called thylakoids which are put into stacks called grana. The fluid around the thylakoids is the stroma.

In plants, algae, and some bacteria

Chloroplast

Plastids

Chromoplasts Contains pigments Carotene-orange Xanthophyll-yellow Phycoerythrin-red Fucoxanthin-brown Aids in

photosynthesis and stores food

Leukoplasts Colorless plastids Stores starch and

other plant nutrients

Mitochondria

Organelles that release energy from food molecules to make high-energy compounds the cell can use to power growth, development, and movement

“ the powerhouse of the cell” Smooth outer layer, folded inner

layer

Mitochondria

Typical Animal Cell

Typical Plant Cell