CELLS STRUCTURE AND FUNCTION

CHAPTER 7

IDENTIFY THE CLASS OF LIPIDS THAT FORM BIOLOGICAL MEMBRANES (CELL MEMBRANE)?

Phospholipids

Lipid monomer = gylcerol and fatty acids

EXPLAIN WHAT IT MEANS TO BE A POLAR MOLECULE

DISTINGUISH BETWEEN THE TERMS HYDROPHILIC AND HYDROPHOBIC

DO YOU REMEMBER ANY OF THE EIGHT CHARACTERISTICS OF LIVING THINGS?

1. Living things are based on a universal genetic code (DNA)

2. Living things grow and develop3. Living things respond to their environment

(stimulus)4. Living things reproduce5. Living things maintain a stable internal

environment (homeostasis)6. Living things obtain and use material and energy

(metabolism)7. Living things are made up of CELLS8. Taken as a group, living things evolve over time

SOME SHORT VIDEOS/SONGS FOR CELL THEORY

History and Scientists of Cell Theory

Cell Theory Rap :)

ANTON VAN LEEUWENHOEK

Developed the first microscope

ROBERT HOOKE (1665)

English physicist used a primitive compound microscope to look at plant tissue (stems, wood, and cork).

Discovered cells He called the chambers “cells” because they

reminded him of the small rooms in a monastery

ROBERT BROWN

Discovered the nucleus

MATHIAS SCHLEIDEN

Stated that all plants are made of cells

THEODOR SCHWANN

Stated that all animals are made of cells

RUDOLF VIRCHOW (1855)

Stated that all cells arise from the division of preexisting cells

THE CELL THEORY:

All living things are composed of cells

Cells are the basic unit of structure & function in living things

All cells come from preexisting cells

TWO TYPES OF CELLS:

TWO TYPES OF CELLS:

Prokaryotic Cell or Prokaryote – unicellular organism that lacks a nucleus

pro = before; karyon = nucleus or kernel contain cell membranes and cytoplasm but no

nucleus DNA is scattered through cytoplasm examples: bacteria

Eukaryotic Cell or Eukaryote – organism whose cells contain a nucleus ( plant and animal)

eu = true; karyon = nucleus or kernel contain a nucleus that holds DNA and membrane

bound organelles that have specific functions examples: all plants, animals, some fungi, some

microorganisms

TWO CATEGORIES OF CELLS

DIFFERENCES BETWEEN PROKARYOTIC AND EUKARYOTIC CELLS:

No Nucleus (Nucleoid)

No membrane-bound organelles

“O” shaped chromosome (plasmid)

Have a Nucleus

Membrane-bound organelles

“X” shaped chromosomes

Prokaryotes: Eukaryotes:

Two categories of cells

Prokaryotic Eukaryotic

-No Nucleus

-Nucleus

-Smaller Ribosomes less complex

-Less complex

-DNA is X shaped

- Ribosomes larger and complex

-Membrane bound organelles

-Complex-Cell wall (plants and bacteria)

-DNA is circular

-Cell membrane-DNA-Cytoplasm-Ribosomes

-Multicellular

-Living things

-Unicellular

0.1-10µm10-100µm

ANIMAL CELL - EUKARYOTIC

ProkaryoticPlant Cell - Eukaryotic

PROKARYOTES AND EUKARYOTES:

Cell Organelles

How small are cells?How much is a micrometer?

1 micrometer (µm) = 1/1,000,000 m

Typical cell size = 5 to 50 µm in diameterIn a dice that is 1 cm3

We could fit 1,000,000 cellsCells Alive

How small are cells?

Cell Organelles: specialized structures that perform a specific

function inside of a cellCytoplasmNucleusNucleolusNuclear EnvelopeVacuoleLysosomeCytoskeletonCentrioles

RibosomesEndoplasmic

ReticulumGolgi ApparatusChloroplastMitochondriaCell WallCell membraneCilia & Flagella

Cytoplasm:Found: between the nucleus and the

cell membraneStructure: a clear “jelly-like” materialFunction: supports the organelles

Nucleus: control center of the cell

Found: in the cytoplasm near middle of cell

Structure: filled with chromatin (tightly coiled DNA)

Function: Stores hereditary information (DNA)

Prokaryotic cells lack a nucleus, but they do contain DNA

Chromatin and Chromosomes:Inside the nucleus are fine strands of

chromatin = a complex of DNA bound to protein

Chromatin coil up and become densely packed, forming chromosomesChromosomes are visible under a

microscope when a cell divides

Nucleolus and Nuclear Envelope:

Nucleolus – small dense region within the nucleus where ribosomes are synthesized

Nuclear Envelope – double membrane (lipid bilayer) that surrounds the nucleus -allows materials to move out of the nucleusNuclear Pore – allows RNA and proteins out of

the nucleus

Vacuole:Found: in the cytoplasmStructure: sac-like, fluid-filled organelles

Plant cells, there is a single large central vacuole filled with fluid - can occupy up to 90% of the cell’s volume

Animal cells – much smallerFunction: storage structure (water, salts,

proteins, and carbohydrates) AnimalAnimal

Plant

Paramecium’s Contractile Vacuole

Contracts rhythmically to pump excess water out of the cell – controls the water content of the organism

Paramecium Contractile Vacuole

Lysosomes:Found: In the cytoplasmStructure: Small enzyme filled organellesFunction: Breakdown large organic molecules,

and old nonfunctioning organellesRemoves “junk” that would clutter the cellKnown as the “Clean Up Crew” Found in animal cells and specialized

plant cellsSome humans have diseases that result from lysosomes that fail to function properly.

Cytoskeleton:Found: Throughout the cellStructure: A network of

protein filamentsMicrotubules (25 nm)Microfilaments (7nm)

Function: Gives cells structure; helps to maintain shape & size; involved in cell movementHelps to transport materials

between different parts of the cell

Network of protein strands (scaffold)

Microfilaments:Thin threads made of actin (structural

protein) Supports the cellContribute to cell movement

Microtubules:Larger strands; hollow tubes made of tubulin

(proteins)Maintain cell shapeImportant in cell division – forms the mitotic

spindle which helps to separate chromosomesForm centrioles in animal cellsHelp build cilia and flagella

Centrioles:Found: Within the cytoplasm only in animal

cellsStructure: Made of a microtubules (tubulin)

arranged in 9 groups of 3

Function: Used to organize cell division (mitosis)

1

2

3

4

5

6

7

8 9

Centrioles - Mitosis

Cilia:Short hairs present in large numbers

Propel unicellular organismsLine cells of respiratory tract

Flagella:Longer hairs that are less numerous

Found on sperm cellsWhip back and forth

Ribosomes:Found: Most numerous organelle – found

throughout the cytoplasm in all cells Structure: Small and grain-like, made of large and

small subunits; not surrounded by a membraneFunction: Produce PROTEINS by following

coded instructions that come from DNAMade of RNA and protein in the nucleolus &

transported to the cytoplasm

Endoplasmic Reticulum (ER):Found: just outside the nucleusStructure: System of membranous

tubules & sacsFunction: Moves molecules from one part

of the cell to anotherIntracellular Highway

Rough ER:Dotted with ribosomesInvolved in the synthesis of proteinsAbundant in cells that make large amounts

of protein

Smooth ER:Does not have ribosomes attached Contains collections of enzymes that

perform specialized tasks (i.e. detoxifying - liver)

Golgi Apparatus:Found: in the cytoplasmStructure: Processing, packaging, and

secreting organelleFunction: Modifies, sorts and packages

proteins and other materials for storage or release

Works with the ERModifies proteins for export

Mitochondria:Found: in the cytoplasmFunction: Convert chemical energy stored in

food into compounds that the cell can use – “powerhouse” of the cellTransfer energy to ATP (main energy currency)Surrounded by two membranes and contain

DNAMost numerous in cells with high energy requirements (liver & muscle)

How Cells Obtain Energy

Chloroplast:Found: Only in the cytoplasm of plant cellsStructure: Stack of membranes that contain

photosynthetic pigments (chlorophyll)Function: Capture energy from the sun&

convert it to chemical energy (food) - photosynthesisSurrounded by two membranes and contain DNAContains the green pigment chlorophyll

Plastid – major organelle found in plant and algae cells. Plastids are the site of manufacture and storage of important chemical compounds used by the cell. They often contain pigments used in photosynthesis, and the types of pigments present can change or determine the cell's color. Plastids can also store products like starch, fat, protein and can synthesize fatty acids.

Cell Wall:Found: Rigid structure outside the cell

membraneStructure: Made of celluloseFunction: Supports and protects the cellFound only in plant cells

Cell Membrane:Found: Located around the perimeter of the

cell Structure: Made primarily of lipids and

proteinsFunction: Regulates what leaves and enters

the cell and provides protection and supportSelectively permeable

Fluid Mosaic Model:

Components of Cell Membrane:1. Phospholipids – polar head & nonpolar

tails2. Integral Proteins – imbedded in lipid

bilayer; usually have carbohydrates attached to them

3. Peripheral Proteins – surface only

Animal Cell:

Plant Cell:

Animal Cell - Label

Cell membrane Centriole

Cytoplasm

Rough ER

Smooth ER

Ribosomes

Golgi ApparatusMitochondria

Vacuole

Nuclear envelop

e

Nucleolus

Nucleus

Lysosome

Plant Cell - LabelCytoplasm

Plastid

Rough ER

Smooth ER

Ribosomes

Golgi ApparatusMitochondria

Chloroplast

Nuclear envelope

Nucleolus

Nucleus

Vacuole

Cell membrane

Cell wall

Plant and Animal Cell Comparison

Classification – Prokaryotes/Eukaryotes

Prokaryotes (Kingdom Monera): 1. Archaea (love extreme cold or heat – food is diverse) 2. Bacteria – regular prokaryotes

Eukaryotes: Everything else (plant, animal, fungi, ciliates, etc.)

Great websites to check out!Interactive Cell Models – Cells Alive

http://www.cellsalive.com/index.htm

Inside a Cell – Learn.Genetics (University of Utah)http://learn.genetics.utah.edu/content/begin/cells/insideacell/

Video – BBC Secret Universe: The Hidden

Life of the Cellhttp://www.youtube.com/watch?v=4GZXRMG5i_w

Video – Inside the Cellhttp://www.youtube.com/watch?v=Ao9cVhwPg84