1. Cell Structure and Function
Chapter 2

2. Lesson 1: Cells and Life

3. Understanding Cells People didn’t always know about cells
Too small to be seen without proper tools
Robert Hooke (English Scientist)
300 years ago he built a microscope
Used his microscope to look at cork (from oak tree)
Small openings he saw reminded him of the rooms that Monks live in called “cells”

4. Cell Theory After Hooke’s discovery, microscopes were improved
Scientists began looking for cells in many other places (pond water, blood)
The newer microscopes enabled scientists to see structures inside of cells.
Matthias Schleiden, a German scientist, used the microscope to look at plant cells.
Theodor Schwann used the microscope to study animal cells
Both scientists realized that plant and animal cells have similar structures.

5. Cell Theory
Rudolf Virchow, a German doctor proposed that all cells come from previously existing cells.
The observations of these scientists were combined to form THE CELL THEORY 1 2 3

6. Basic Cell Substances
Cells are made of smaller parts that are joined together, called macromolecules
Macromolecules form by joining many small molecules together.
The main ingredient of macromolecules is water
More than 70% of a cell is water
Water surrounds cells
This surrounding water helps insulate your body
This helps your body maintain homeostasis, or a stable internal environment

7. There are 4 types of macromolecules:
Nucleic Acids
Contain genetic information (make up your DNA)
Proteins-Amino acids
Communication, Transport, Chemical Breakdown, and Structural Support
Lipids-Fats
Energy Storage, protective membranes, and communication
Carbohydrates –sugars and starches
Energy storage, structural support and communication

8. Macromolecules

9. Lesson 2: The Cell

10. Cell Shape and Movement
Cells come in many shapes and sizes
The size and shape of the cell relate to it’s function
Cell structures that make up a cell also have unique functions
In a cell, the different structures perform different functions that keep a cell alive
They work together!

11. Cell Membrane vs Cell Wall
All cells are surrounded by a protective covering called a membrane.
A Cell Membrane is a flexible covering that protects the inside of a cell from the environment outside.
Membranes are mostly made up of proteins and lipids
Some cells are also surrounded by a structure called a cell wall
A Cell Wall is a stiff structure outside the cell membrane.
Cell Walls protect against harmful attacks, as well as help with shape and support

12. Cell Membrane vs Cell Wall

13. Cell Appendages Arms and legs are appendages on an organism
Cells can have Flagella or Cilia to help them move

14. Cytoplasm and Cytoskeleton
Most of the Cells water is in the Cytoplasm
Cytoplasm: a fluid inside of a cell that contains salts and other molecules.
The cytoplasm also contains a Cytoskeleton
Cytoskeleton: a network of threadlike proteins that are joined together in a framework
This helps give the cell it’s shape

15. Cytoplasm and Cytoskeleton

16. Prokaryotic Cells vs. Eukaryotic Cells
Prokaryotic – Genetic material (DNA) is not surrounded by a membrane (nucleus)
Most Prokaryotic cells are unicellular organisms called Prokaryotes
Eukaryotic – Genetic material (DNA) is surrounded by a membrane
Has many other structures called organelles, each having their own function

17. Cell Organelles Nucleus Largest organelle Directs cell activities
Contains Genetic information (DNA)

18. Manufacturing Molecules
Proteins are made in tiny structures called a Ribosome
Ribosomes don’t have membranes surrounding them.
Ribosomes are round floating in the Cytoplasm as well as attached to a web like structure called the Endoplasmic Reticulum

19. Manufacturing Molecules
Endoplasmic Reticulum
Rough E.R. – with ribosomes attached to the side
Where proteins are manufactured
Smooth E.R. – without ribosomes
Where lipids such as cholesterol are made
Helps remove harmful substances from the cell

20. Processing Energy - Mitochondria
Mitochondria are surrounded by two membranes
Energy is released during a chemical reaction that takes place in the mitochondria
This energy is stored in high- energy molecules called ATP
ATP is fuel for cellular processes

21. Processing Mitochondria - Chloroplasts
Chloroplasts are found in plant cells and some protists
Chloroplasts use light energy and make food-a sugar called glucose- from water and carbon dioxide in a process called photosynthesis
This sugar glucose, contains energy that can be released when the plant cell needs it

22. Golgi Apparatus Golgi apparatus
Prepares proteins for their specific jobs or functions
Then it packages the proteins into tiny, membrane bound, ball like structures called vesicles
Vesicles are structures that transport substances from one area of a cell to another area of a cell.
Some Vesicles in an animal cell are called lysosomes
Lysosomes contain substances that help break down and recycle cellular components

23. Golgi Apparatus, Vesicles, and Lysosomes

24. Storing Molecules Vacuoles Saclike structures
Stores food, water, and waste material
Plant cells usually have one very large vacuole that stores water and other substances

25. Lesson 3: Moving Cellular Material

26. Passive Transport A cell membrane is semipermeable
Semipermeable means that the membrane only allows certain substances to enter or leave the cell

27. Passive Transport
2 water molecules
Passive transport is the movement of substances through a cell membrane without using the cell’s energy
Molecules must be small to pass through membranes
Such as Oxygen or Carbon Dioxide molecules
Passive transport depends on the amount of a substance on each side of a membrane
Example: Suppose there are more Oxygen molecules (O2) outside of a cell than inside it
Will the O2 molecules move? Which direction will they move?
Yes, the O2 molecules will move into that cell until the amount of O2 is equal on both sides of the cell’s membrane
8 water molecules
5 Oxygen molecules
4 Oxygen molecules

28. Passive Transport
The concentration of substance is the amount per unit volume
Diffusion
The movement of substances from an area of higher concentration to an area of lower concentration
Usually, diffusion will continue through a membrane until the concentration of a substance is the same on both sides of the membrane

29. Passive Transport Osmosis-The Diffusion of water
Diffusion refers to the movement of any small molecules from higher to lower concentrations
Osmosis is the diffusion of only water molecules through a membrane
Example: Water diffusing out of a plant cell
Concentration of water in air is less than water in vacuoles of plant cell
Water continues to diffuse into the air until the concentrations of water inside the plant’s cells and in the air are equal
If plant is not watered to replace the water it loses, what will eventually happen?
It will wilt and eventually die
Salt Molecules
Water Molecules

30. Facilitated Diffusion
Some molecules are too large or chemically unable to travel through a membrane by diffusion
Facilitated diffusion happens when molecules pass through a cell membrane using special proteins celled transport proteins
Like diffusion, no energy is required for facilitated diffusion
Channel proteins form pores through the membrane
Carrier Proteins carry large molecules such as sugar through the membrane

31. Active Transport
The movement of substances through a cell membrane only by using the cell’s energy is Active Transport
When substances move from a low concentration to a higher concentration it requires energy

32. Endocytosis & Exocytosis
When a substance is too large to enter a cell membrane by diffusion or by using a transport protein they must enter by another process called Endocytosis:
The process during which a cell takes in a substance by surrounding it with the cell membrane is called Endocytosis
When a substance is too large to leave a cell it leaves through a process called Exocytosis
Exocytosis: The process during which a cell’s vesicles release their contents outside the cell

33. Cell Size and Transport
Remember: the movement of nutrients, waste materials and other substances into and out of a cell are very important for survival
For Movement to happen, the area of cell membrane must be large compared to the volume of the cell
Area of cell membrane = Cell’s Surface Area
Amount of space inside cell = Cell’s Volume

34. Cell Size and Transport
As the cell grows, both volume and surface area grow
Volume of cell increases faster than the cell’s surface area
Why is this a problem?
As cell grows it needs larger amounts of nutrients and create more waste material. But the surface area of the cell’s membrane is too small to move enough nutrients and wastes into or out of cell for it to survive

35. Lesson 4: Cells and Energy

36. Cellular Respiration All living things need energy to survive
Cellular Respiration is a series of chemical reactions that convert the energy in food molecules into a usable form of energy called ATP

37. Cellular Respiration Glycolysis: The first Step
Occurs in the cytoplasm
Process in which glucose, a sugar, is broken down into smaller molecules
Produces some ATP, but Glycolysis also needs ATP to happen

38. Cellular Respiration 2nd Step: Occurs in the Mitochondria
Requires Oxygen (O2)
The smaller molecules made from Glycolysis are broken down

39. Cellular Respiration
Large amounts of ATP – usable energy- are produced
Cells use this ATP to power ALL cellular processes
Two waste products – water (H2O) and Carbon Dioxide (CO2) – are given off during this step

40. Fermentation
A reaction that both eukaryotic and prokaryotic cells can use to obtain energy from food when oxygen levels are too low
Takes place in the cell’s cytoplasm
Produces less ATP than cellular respiration because no oxygen is used

41. Fermentation Lactic Acid fermentation:
When Glucose is converted into ATP and produces Lactic Acid as a waste product
Muscle cells in humans and other animals use lactic- acid fermentation to produce energy during excercise

42. Fermentation
Some types of bacteria make ATP through a process called Alcohol Fermentation
Instead of producing lactic acid, an alcohol called ethanol and CO2 are produced.
Some bread is made using yeast
The CO2 produced during alcohol fermentation makes the dough rise

43. Photosynthesis
Plants and some unicellular organisms obtain energy from light
Photosynthesis is a series of chemical reactions that convert light energy, water and CO2 into the food energy molecule glucose and give off Oxygen
Photosynthesis requires light energy. In plants, pigments such as chlorophyll absorb the light energy
Green light is reflected as green color seen in leaves. Plants also reflect other colors we see such as red and yellow.
Light energy powers chemical reactions that take place in the chloroplasts of plant cells.

44. The Photosynthesis & Cellular Respiration Relationship
Photosynthesis uses CO2 that is released during cellular respiration to make food energy and release oxygen

45. The Photosynthesis & Cellular Respiration Relationship
When an organism eats plant material, it takes in food energy.
An organism’s cells use oxygen released during photosynthesis to convert food energy into usable energy.