QOD 10/17/11

• What is the basic unit of all life?

Cell Structure and Function

Timeline:History of Cells

• Robert Hooke -1665• First person to use the

term cell• From the Latin “cella”

meaning “small chamber”• Father of microscopy

Timeline:History of Cells

• Anton van Leeuwenhoek-1675

• A Dutch cloth merchant who became interested in studying cells.

• Was the first to see and describe bacteria, sperm cells and protista

Timeline:History of Cells

• Rene Dutrochet-1824• 1st scientist to

hypothesize that cells are the basic unit of life.

Timeline:History of Cells

• Robert Brown- 1833• Names the nucleus

and proposes that it has an important role in the control of cellular processes

• Matthias Schleiden (1838) – all plants are composed of cells.

• Theodor Schwann (1839) – all animals are composed of cells.

Timeline:History of Cells

Timeline:History of Cells

• Rudolf Virchow (1856) • “Where a cell exists,

there a cell must previously have existed”

How do we see cells?

• There are 3 kinds of microscopes:

1. Light Microscope• Magnifies up to 1000x

2. Scanning Electron Microscope (SEM)• Magnifies up to 100000x

3. Transmission Electron Microscope (TEM)• Magnifies up to 200000x

Scanning Electron Microscope

• Can look at surface of the specimen

• Specimen is coated in gold and an electron beam is sent into it, electrons bounce off onto a piece of film, which forms a 3-D picture of the specimen

Transmission Electron Microscope

• Can only look at thin sections of the specimen in 2-D

• A beam of electrons is sent through the thin slice of specimen, the image is enlarged and put on film

Electron micrographs of rabbit trachea

A) transmission electron micrograph - TEM

B) scanning electron micrograph - SEM

Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

A Paramecium

QOD 10/18/11

• Who is the father of microscopy?

Robert Hooke

• NOTE: I will be collecting QODs on Friday, you should have 25 by then…

• QUIZ 10/25 over cell organelles and functions

3 Parts of the Cell Theory

1. All living things are composed of cells.

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

3. All cells come from preexisting cells.

Number of Cells• Unicellular – composed of one cell

• Multicellular- composed of many cells that may organize

•Colonial – unicellular organisms that group together

There are 2 main types of cells:

Prokaryotic Cells

• Lack a true nucleus and membrane bound organelles

• Much smaller than eukaryotic cells

• Bacteria is an example

Basic Bacterial Cell(fill in blanks on notes)

Eukaryotic Cells• Have a true

nucleus and membrane bound organelles

• Include plants, animals, fungi and protista

Plasma Membrane

Cell Membrane• Present in all

cells• Regulates the

passage into and out of the cell

• Provides protection and shape

Plasma Membrane Structure• Composed of a double layer of phospholipids• It is semi-permeable (some things get in, some don’t) • Lipid bilayer is made up of hydrophilic and

hydrophobic regions

Cytoplasm• Also found in all

cells• Cytoplasm: the

liquid part of the cell• This is where

chemical reactions occur

• Mainly made of water

Nucleus• contains the DNA of

the cell–DNA is also called

chromosomes and chromatin

• surrounded by a membrane called the nuclear envelope

• Controls the cell’s activities

10/19/11

•What is the leader of the cell?–Nucleus!!

Nucleolus

• Where the DNA is concentrated within the nucleus

• This is where ribosomes are produced

Ribosomes• Make proteins • May be free in

the cytoplasm OR bound to the rough ER

Endoplasmic Reticulum• Comes from the

Greek Endo = “within” Latin reticulum = “network.”

• A membrane network within the cytoplasm

• This is the assembly line of the cell

Rough ER• Produces lipids and proteins• Called rough because of ribosomes• Things made here leave by Vesicles (little

sacs) that pinch off and move in the cytoplasm

Smooth ER

• No ribosomes• Builds lipids

Golgi Apparatus• Processes unfinished proteins• Packages finished proteins• Distributes finished proteins (in

vesicles)• Like the mailman of the cell

Vesicles

• Small, spherically shaped sacs that are surrounded by a single membrane and that are classified by their contents

Lysosomes• Vesicles that

contain digestive enzymes

• Used to digest cell invaders, old organelles, or food

• Also help to “kill” cells when needed, by releasing their enzymes

• Only in Animal Cells

• The cell’s powerhouse

• Involved in cellular respiration

• Helps to convert “food” into cellular energy = ATP

Mitochondria

Cytoskeleton

• A network of thin tubes and filaments made of proteins that crisscross in the cytosol.

– Give the cell shape and structure

Cilia and Flagella• Hair-like structures that

extend from the surface of a cell and they assist in movement

• Cilia are short and present in large numbers

• Flagella are long and usually very few are present

• Both are made of microtubules

QOD 10/20/11

• The cell’s ATP is made in which organelle?

–MITOCHONDRIA

Centrioles• Made of

microtubules• Organize movement

of all microtubules during cell division

• Only in animal cells

Differences in Plant and Animal Cells

• Plants have cell walls, chloroplasts, plastids, and a central vacuole; animals have none of these

• Animals have lysosomes and centrioles, while plants do not

Central Vacuole• Storage area• Stores nutrients in

animal cells• Helps to give

support in plant cells- holds water

Cell Wall• The cell wall is a rigid

structure that is found in plants, fungi, and bacteria cells

• Made mainly of cellulose• Has pores for the

movement of water, ions, and nutrients

• It supports and maintains the shape of the cell and is extremely strong.

Plastids• Organelles that are

surrounded by a double membrane and contain their own DNA (like mitochondria)

• Examples:– Chloroplasts- contain

green pigments– Chromoplasts- contain

other color pigments– Amyloplasts- store starch

• Site of photosynthesis• Contains the green pigment chlorophyll

Chloroplasts

QOD 10/20/10

• What do plant cells have that animal cells do not?

QOD 11/1/11

• What is the function of the cell membrane?

QOD 11/2/11

• What is osmosis?

Cell Transport

Cellular Transport

• Concentration gradient- from high concentration to low concentration

• Passive Transport - no energy needed– Goes WITH the concentration gradient– Examples are diffusion, osmosis, and

facilitated diffusion• Active Transport - needs energy

– Goes AGAINST the concentration gradient– Examples are protein pumps, endocytosis,

and exocytosis

Diffusion• Diffusion- The

movement of molecules from an area of high concentration to an area of low concentration–Movement WITH

the concentration gradient (passive transport)

Diffusion

• Diffusion occurs until equilibrium is reached– Equilibrium is when the concentration of

molecules is the same throughout a space they occupy

Osmosis• Water is one of the small, polar

substances that can easily pass through the selectively permeable plasma membrane

• The diffusion of water across a membrane is called osmosis.

• Water moves from high to low concentration

(passive transport)

Isotonic Solution (Iso=Same) The concentration of water molecules and solutes

are the same inside and outside the cell.

Remember, solutes are dissolved in water, like salt or sugar

Water molecules will move across the membrane at the same rate in both directions.

NO NET MOVEMENT, cell remains the same

Solute concentration

sare equal on both sidesof the cell

Hypertonic Solution (Hyper=above)

• Hypertonic solution = high solute / lower water on outside

• Water will move OUT of the cell• Plant cells will lose Turgor Pressure (the pressure

water molecules exert on the cell wall)• Plasmolysis occurs which is where cell

membranes shrivel

water moves out of the cell

cell will shrink

Hypotonic Solution (Hypo=below) • Lower concentration of solute on outside of cell

when compared to the inside of cell• Water will move IN the cell• Cell will swell or possibly burst (called cytolysis)• Plant cells will gain Turgor Pressure

Water moves into the cell

Cell May Burst

Plasma Membrane

• Remember, the function of the plasma membrane is control the movement materials into and out of the cell

Plasma Membrane

• The plasma membrane is selectively permeable which means some things can get through and some cannot.• It is made of a phospholipid bilayer, but also

contains embedded proteins that help with transport into it

• Small molecules pass– Water, carbon dioxide, and oxygen

• Large molecules like glucose and ions do not pass

Facilitated Diffusion• Proteins help transport molecules WITH their

concentration gradient that cannot diffuse by themselves (from HIGH to LOW concentration- passive transport)

• Carrier proteins or Channel Proteins assist these molecules with facilitated diffusion

Facilitated Diffusion• Different carrier proteins will transport different

molecules (each protein is specific!)• Glucose is transported this way• Molecules can be moved in OR out of the cell

Active Transport

• This type of transport requires energy and usually moves against the concentration gradient

• Carrier proteins are usually involved, but may be called protein pumps

Endo and Exocytosis• Some

substances are too large to transport into the cell through carrier proteins– So, endocytosis

and exocytosis are used

Endo and Exocytosis• Endocytosis is the process by which cells take

substances IN • Exocytosis is the process by which cells let

substances OUT