CELLSChapter 7

CELL THEORY All living things are made of cells Cells are the basic units of structure

and function in living things New cells are produced from existing

cells

MICROSCOPES

Compound light microscope – allows light to pass through a specimen and uses two lenses to form an imageMagnifies to 1000xStains or dyes are used to show specific

featuresFluorescent dies are used to tag molecules produced by cells

MICROSCOPES

Electron microscopes – use beams of electrons that are focused by magnetic fields – can be used to see objects one billionth of a meterTransmission electron microscopes – thin slices , electrons pass through the specimen - 2D image

Scanning electron microscopes – a pencil-like beam is scanned over the surface – makes a 3D image

SEM images

PROKARYOTES AND EUKARYOTES All cells have a cell membrane - a thin

flexible barrier surrounding the cell Not all cells have a nucleus – a large

membrane-enclosed structure that contains genetic material in the form of DNA and controls many of the cells activities Prokaryotes - do not have a nucleus

Typically smaller and more simple Eukaryotes = have a nucleus

Typically larger and more complex Can be unicellular or multicellular

7.2 CELL STRUCTURE – EUKARYOTIC CELLS

The cytoplasm is the fluid portion of the cell outside the nucleus.

Many cellular structures act as if they are specialized organs. These structures are known as organelles, literally “little organs.”

THE CELL AS A FACTORYThe eukaryotic cell is much like a living version

of a modern factory. The specialized machines and assembly lines of

the factory can be compared to the different organelles of the cell.

Cells, like factories, follow instructions and produce products.

THE NUCLEUS

The nucleus = the control center of the cell It contains most of the cell’s DNA, the

instructions for making proteins and other important molecules

Nuclear envelope = surrounds the nucleus contains pores (holes) that allow material to go in and out of the nucleus

Chromosomes – carry the cell’s genetic information (DNA)

Found in the nucleus Nucleolus – a small dense region in the nucleus

Ribosomes are assembled here

ORGANELLES THAT STORE, CLEAN UP, AND SUPPORT

Vacuoles –large saclike structures with membranes Store water, salt, proteins, and carbohydrates In plants there is often 1 vacuole filled with liquid Also found in unicellular organisms and animals for storing

and moving materials

ORGANELLES THAT STORE, CLEAN UP, AND SUPPORT

Lysosomes – small organelles filled with enzymes Break down lipids (fats) , carbohydrates,

and proteinsHelp break down “old” organelles -

removes “junk” from the cellFound in animal cells and some plant cells

ORGANELLES THAT STORE, CLEAN UP, AND SUPPORTCytoskeleton – a network of protein

filaments that give cells shape and internal organizationHelps maintain cell shape and involved in

movementMicrofilaments – form a framework that

supports the cell and help them moveMicrotubules – hollow structures made of

proteins called tubulins and are involved in maintaining cell shape and in cell division Also form cilia and flagella Centrioles – located near the nucleus and organize cell

division in animals (made of tubulins)

ORGANELLES THAT BUILD PROTEIN

Ribosomes – the “protein factory” - where proteins are assembledsmall particles of RNA and protein found

throughout the cytoplasm in all cells. produce proteins by following coded instructions

that come from DNA. Each ribosome is like a small machine in a factory,

turning out proteins on orders that come from its DNA “boss.”

ORGANELLES THAT BUILD PROTEIN

Endoplasmic reticulum (ER) – an internal membrane system where lipids are assembled and proteins and other materials are exported from the cell. Rough endoplasmic reticulum (rough ER) – the ER

where protein synthesis occurs ribosomes on its surface Proteins made in the rough ER can be exported out of the cell or

transported to other locations in the cell Smooth endoplasmic reticulum (smooth ER) – the ER

where no ribosomes are found Contains enzymes to do tasks like making membrane lipids or

detoxification of drugs

ORGANELLES THAT BUILD PROTEIN

Golgi Apparatus - modifies, sorts and packages proteins and other materials from the ER for storage in the cell or transport out of the cell. Looks like a stack of flattened membranes “Ships” proteins to their final destination

ORGANELLES THAT CAPTURE AND RELEASE ENERGY

Chloroplasts – capture the energy from sunlight and convert it into food (photosynthesis) Found in plants and some other organisms “solar power plants”

ORGANELLES THAT CAPTURE AND RELEASE ENERGY

Mitochondria – “The POWER HOUSE” convert the chemical energy stored in food into

compounds easier for the cell to use In humans, you inherit most of your mitochondria

from your mom Contain small DNA molecules which suggest they may

have been descended from independent microorganisms.

CELLULAR BOUNDARIES Cell Wall – supports, shapes, and protects the

cell Allow water, oxygen, carbon dioxide to pass through Found in prokaryotes and eukaryotes (NOT ANIMALS) Provides strength in plants (wood is made of mostly

cell walls) Cell Membrane – controls what enters and

leaves the cell and supports Made of a lipid bilayer (see the next slide)

CELLULAR BOUNDARIES

The cell membrane is made of a double layered sheet with lipids and proteins

The cell membrane is selectively permeable – some substances are allowed to pass and some are not.

PLANT VS ANIMAL CELLS PG 206

7.3 CELL TRANSPORT

Passive Transport = The movement of materials across the cell membrane without using cellular energy is called passive transport. Diffusion - The process by which particles move from an

area of high concentration to an area of lower concentration

PASSIVE TRANSPORT CONT.

Facilitated Diffusion – the process where molecules that cannot directly diffuse across the membrane pass through special protein channelsOsmosis –the diffusion of water

through a selectively permeable

membrane

Water moves across a membrane

until equilibrium is reached

OSMOSISTypes of Solutions Isotonic = When the concentration is the same on both

sides of the membrane Hypertonic = The more concentrated solution Hypotonic = The dilute solution Osmotic pressure = the net movement of water out of or

into a cell exerts a force

ACTIVE TRANSPORT

Active transport = the movement of materials against a concentration difference (requires energy

MOVEMENT OF LARGE MOLECULES

CHAPTER 9 – ENERGY AND EXERCISE (PG 265)

Your body uses energy in the form of ATP Quick energy

First few seconds (50 m of a race) – use ATP stored in cells

Up to 90 seconds (200-300 m) – lactic acid fermentation (make lactic acid – to get rid of it, you need oxygen = breathing hard)

Long-term energy Over 90 seconds – cellular respiration glycogen (carbohydrate stores) are used up in 15-20 minutes followed by other molecules including fats.

CHOOSE THE CORRECT ORGANELLE

1. A.NucleusB.Nuclear

MembraneC.NucleolusD.GolgiE.Smooth ERF. Rough ER

2.

3.

4.

CHOOSE THE CORRECT LETTER

5. 6.

7.

8.

9. 10.

A.VacuoleB.ChloroplastC.CytoplasmD.Cell WallE.Cell MembraneF.Mitochondria

MATCH THE STRUCTURE AND FUNCTION

11. Controls what enters and leaves the cell

12. Gives support to cells, found in plants

13. Contains genetic material in the form of DNA and controls many of the cells activities

14. Makes ribosomes15. fluid portion of the cell

outside the nucleus.16. Controls what goes in and

out of the nucleus

A.NucleusB.Nuclear

MembraneC.NucleolusD.CytoplasmE.Cell WallF.Cell

Membrane

MATCH THE STRUCTURE AND FUNCTION

17. Storage18. Breaks down “old junk”19. “Protein factory”20. Membrane that has

ribosomes on it – makes proteins

21. Membrane that does not have ribosomes – makes lipids

22. modifies, sorts and packages proteins and other materials

A.RibosomesB.Smooth ERC.Rough ERD.Golgi BodiesE.VacuoleF.Lysosome

MATCH THE STRUCTURE TO THE FUNCTION

23. A cell with a nucleus

24. A cell without a nucleus

25. The “power house”

26. Structures in the nucleus made of DNA

27. Convert energy in sunlight to food

A.MitochondrionB.ChloroplastC.ChromosomesD.ProkaryoteE.Eukaryote