Discovery of the Cell Robert Hooke 16651 stperson

Discovery of the Cell Robert Hooke: 16651 stperson to see a cell Used a microscope to look at a piece of cork Saw small, empty “boxes”which reminded him of the small rooms monks lived in called cells. These “cells”weren’t alive. From Robert Hooke's Micrographia (1667 ed. ). National Library of Medicine

1 st Living Cells Anton van Leeuwenhoek 1 st person to see and describe living cells: 1673 Made his own microscopes Could magnify 200 times! Described the things he observed as “Animalcules” Wrote many description of his discoveries to the Royal Society in Londo. Many of his drawings and descriptions are very accurate even today

Cell Theory Developement From the 1 stobservation of the cell by Hooke and Leeuwenhoek it took 150 years to develop a theory that explained them. A lot of reasons for the length of time. Not many people had access to microscopes. Problems with making lenses. Previous knowledge/thoughts about where life came from (spontaneous generation). Development of technology to make lenses allowed for more people to study cells.

The Cell Theory 1. All Living things contain a cell or cells. 2. Cells are the basic unit of structure and function of life Anything smaller than a cell can’t be alive 3. Cells come only from other cells. Disproved spontaneous generation.

Two Basic Types of Cells Prokaryotes & Eukaryotes

PROKARYOTIC CELLS Only Unicellular (Single Celled) DO NOT have a NUCLEUS Examples include: The Kingdom Monera – Bacteria Only

PROKARYOTIC CELLS DO NOT have a NUCLEUS DO NOT have membrane bound organelles

Information about Prokaryotics Important Facts Evolved 4 billion years ago No membrane bound nucleus or organelles Some have flagella – whip like tail Some have cilia – short, hair like extension Pro = Before Karyon = Nucleus

Eukaryotic Cells Only Unicellular or Multicellular DO HAVE a NUCLEUS Examples include: The Kingdom Protista, Fungi, Plantae, and Animalia

Eukaryotic Cell

Information about Eukaryotics Important Facts Evolved 3 billion years later than bacteria Have membrane bound nuclei and organelles More complex than Prokaryotes Some unicellular organisms can have flagella or cilia Eu = True Karyon = Nucleus

There are two main types of eukaryotic cells animal and plant cells What is inside of animal and plant cells?

What is inside the eukaryotic cell? Cell Organelles Organelle= “little organ” Found only inside eukaryotic cells Everything in a cell except the nucleus is cytoplasm

Cell Membrane Boundary of the cell Made of a phospholipid bilayer Part is hydrophobic (water fearing) and part is hydrophillic (water loving)

The Nucleus Control center of the cell Contains DNA Surrounded by a double membrane Usually the easiest organelle to see under a microscope Usually one per cell

What is inside the nuclear envelope?

Inside the Nucleus Chromatin granular material inside nucleus Consists of DNA bound to proteins Chromosomes – what chromatin condenses to form Contains the genetic nformation Nucleolus Small dense region where assembly of ribosomes begins

Outside of the Nucleus

Endoplasmic Reticulum A. k. a. “ER” Connected to nuclear membrane Highway of the cell Rough ER: studded with ribosomes; it makes proteins Smooth ER: no ribosomes; it makes lipids

Ribosome Site of protein synthesis Found attached to rough ER or floating free in cytoplasm Produced in the nucleolus Two parts to the ribsome Large and small subunits that act together “reads” messagner RNA and makes polypeptides (proteins)

Golgi Apparatus Looks like a stack of plates Acts like the post office of the cell Modifies, stores and sorts packages (proteins)

Lysosomes Garbage disposal of the cell Contain digestive enzymes that break down wastes

Mitochondria “Powerhouse of the cell” Structure – organelle with double membranes; the inner membrane has many folds Cellular respiration occurs here to release energy for the cell to use Bound by a double membrane Has its own unique strand of DNA

Vacuoles Large central vacuole usually in plant cells Many smaller vacuoles in animal cells Storage center for the cell container for water, food, enzymes, wastes, pigments, etc.

Cytoskeleton Acts as skeleton and muscle Provides shape and structure Helps move organelles around the cell Made of three types of filaments Microtubules Actin filaments Intermediate filaments

Centriole Aids in cell division Usually found only in animal cells Made of microtubules

There additional organelles in plant cells not found in animal cells

Chloroplast Found only in plant cells Structure – thylakoid membranes are stacked; they contain pigments such as chlorophyll Contains the green pigment chlorophyll Convert solar energy into chemical energy through photosythesis (makes glucose) Bound by a double membrane

CHLOROPLAST

Cell Wall Found in plant and bacterial cells Rigid, protective barrier Located outside of the cell membrane Made of cellulose

Movement of Molecules Diffusion –movement of molecules from HIGH to LOW concentrations Does not require energy Osmosis – the diffusion of water

Movement through a membrane Facilitated diffusion -when substances move across a membrane through specialized protein channels

Active transport – movement of molecules in the cell against the gradient (from LOW to HIGH) Require s energy

Vocabulary to Know Isotonic = same solute as water

Hypotonic = less solute, more wtaer Hypertonic =more solute, less water

Concentration Determination Molecules will move until they are equal on each side of the membrane They will continue to pass back and forth across the membrane staying equal on both sides hypertonic/hypotonic solutions are determined by comparison of solute on each side of the membrane

Why are cells so small? The surface of a cell, its membrane, is the site of exchange between its interior and its external environment. This surface must allow sufficient exchange to support the contents of the cell. As an object increases in size its volume increases as the cube of its linear dimensions while surface area increases as the square. As these cubes illustrate the surface area to volume ratio of a small object is larger than that of a large object of similar shape. This ratio limits how large cells can be.

Cell Specialization Cells develop in different ways to perform different tasks Stem cells Levels of organization Cells Tissues Organs systems