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Cells

Cells. What is Life?. Before we tackle this question, it is important to consider what qualifies something as “living”. Characteristics of Living Things. Cellular organization Growth and development Require energy to survive Cells have DNA Reproduction- all living things reproduce

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Cells

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  1. Cells

  2. What is Life? • Before we tackle this question, it is important to consider what qualifies something as “living”

  3. Characteristics of Living Things • Cellular organization • Growth and development • Require energy to survive • Cells have DNA • Reproduction- all living things reproduce • Sense and respond to change in environment

  4. Living things include animals, plants, protists, fungi and bacteria

  5. Homeostasis • An organism’s outside environment may change, but conditions inside its body must remain the same • Many chemical reactions keep an organism alive • These reactions can only take place when conditions are exactly right • An organism’s ability to maintain a stable, internal condition to survive is called homeostasis

  6. Homeostasis is the maintenance of a stable internal environment For example: Your body maintains a temperature of about 37 degrees Celsius When you get hot, your body responds by sweating When you are cold, your muscles twitch in an attempt to warm you up Some living things maintain homeostasis by changing their environment

  7. A tissue is a group of cells that work together to perform a certain job Ex: blood, muscle, bone, fat, nerves • An organ is a structure that is made of two or more tissues working together to perform a specific function Ex: liver, heart, kidneys, lungs, brain • An organ system is a group of organs working together to perform a certain job Examples: circulatory system, digestive system, nervous system

  8. Robert Hooke • In 1665, Hooke, a physicist and inventor, became the first person to view cells using a slice of cork under a microscope • He named what he saw cells because they reminded him of tiny rooms in a monastery

  9. Anton van Leeuwenhoek1632-1723 • He was the first scientist to view living cells • Using a compound microscope that he invented, he discovered one-celled protists in pond water samples which he named animacules (little animals in Latin) • He also saw bacteria (1676) from teeth scrapings, as well as sperm from dogs and other animals (1677) • 200 years later other scientists discovered animals were made of cells as well

  10. The Cell Theory A. All cells come from pre-existing cells B. All organisms are either unicellular or multi-cellular C. Cells are the basic unit of structure of life

  11. What are some benefits to being multicellular? Unicellular Multicellular Organisms that are composed of many cells (animals, plants, fungi, and some protsists) • An organism made up of one cell (bacteria and some protists)

  12. Benefits to being multi-cellular • Larger size • Longer Life • Specialization- each type of cell has a different job, making multi-cellular organisms more efficient than unicellular organisms

  13. Five similarities of all Cells • Require energy • Produce proteins • Have a cell membrane • All cells divide to make new cells • All have DNA (genetic material)

  14. Eukaryotes Prokaryotes • These are plant and animal cells • These cells have enclosed membrane- bound organelles that carry out specific functions in the cell • Multi-cellular • DNA is stored in a nucleus • These are bacterial cells • Do not have membrane-bound organelles • Unicellular • Lacks a nucleus; instead it has a circular DNA region

  15. Prokaryote Prokaryotes are bacteria They are unicellular organisms They lack a nucleus, Instead, the DNA is coiled as a long, circular strand in the center of the cell Prokaryotes are much smaller in size than eukaryotes Some bacteria have a flagellum that provides them with movement

  16. Biological Molecules Our Body is Built on • Carbohydrates (glucose) • Lipids (fats) • Proteins • Nucleic Acid Cells rely on these to do their job, and in the cell you will soon learn that proteins and lipids are even manufactured there!

  17. Organelles • Tiny cell structures that carry out specific jobs • They are membrane-bound • Found in both plant and animal cells (eukaryotes), but not in bacterial cells

  18. As you will soon see, the cell is like a factory- different organelles working together to make important materials for the cell

  19. The cell membrane is semi-permeable (only some things pass through it)- it controls what goes in and out of the cell-allows certain molecules to pass through

  20. Nucleus • The “control center” of the cell, because it contains DNA, it directs all the cell’s activities • The nucleus is protected and surrounded by a nuclear membrane

  21. Stores DNA….It is the control center of the cell!!

  22. Chromatin Chromatin are very thin strands of genetic material (DNA) that float around in the nucleus (the purple lines) These strands are the reason the nucleus is the “control center” of the cell

  23. Nucleolus • This small structure is located inside the nucleus • It is the site for the production of ribosomes

  24. Ribosomes • Attached to the surface of some endoplasmic reticulum, but also free floating in the cytoplasm • Makes (synthesizes) proteins • Proteins are made here and then sent to the golgi bodies via vesicles • Proteins are responsible for thousands of different chemical reactions that keep us alive and are also responsible for traits we are born with , like eye color and lip shape, etc

  25. The Protein Factories!

  26. Lysosomes Small round structures that contain chemicals that break down large food parts and old, worn-out cell materials They also release enzymes, so that they may be used again More common in animal cells than plant cells

  27. Mitochondria Rod shaped structures with a double- layer membrane The “power houses” of the cell because they produce energy the cell needs to do its work Unlike other organelles, they have their own DNA so they can divide and make more of themselves in the cell! Pretty cool, huh?

  28. Energy Center of the Cell! Uses energy released from glucose molecules

  29. Mitochondria • You eat and the intestines break down food into small molecules • A cell eats and the mitochondria breaks down the molecules for the cell using oxygen and glucose from food.

  30. Structure of the Mitochondria

  31. In which type of cells would you expect to find a lot of mitochondria? Muscle cells contain many mitochondria because our muscles require lots of energy to perform the tasks they do.

  32. Endoplasmic Reticulum A passageway through which proteins and other materials move within the cell Spots on the endoplasmic reticulum are called ribosomes Rough E.R. (has ribosomes)- so it makes proteins Smooth E.R.-(lacks ribosomes) it makes lipids The E.R. is always next to the nucleus

  33. Rough Endoplasmic Reticulum

  34. Smooth E.R. This organelle contains special enzymes for: • Synthesizing lipids (oils, phospholipids, and steroids) • Metabolizing carbohydrates • Detoxification of drugs and poisons Liver cells contain a lot of smooth E.R. with enzymes for detoxification of drugs Testes and Ovaries cells are rich in smooth E.R. with enzymes for making the sex hormones, testosterone and estrogen

  35. Proteins are transported by vesicles that bud off the E.R. and are sent to the golgi body and from the golgi body they bud off and are sent to other parts of the cell

  36. Golgi Bodies (Golgi Complex) • Structures within the cell that look like a flattened stack of pancakes • This structure is like the “post office” • It sorts, packages, modifies proteins and other material, then distributes throughout the cell and out

  37. Golgi Body

  38. Cytoplasm • The cytoplasm is the clear, gel-like fluid that is inside the cells between the cell membrane and the nucleus • It is constantly moving

  39. The jelly-like fluid in the cell that the organelles sit in is the cytoplasm

  40. Cytoskeleton The cytoskeleton acts as a “skeleton” ….. FUNCTIONS: -cell movement -internal movement of organelles -muscle fiber contractions Three types of cytoskeleton: Actin filaments Intermediate filaments Mictrotubles

  41. Plant cells have mostly the same organelles as animal cells, but a few differences do exist..

  42. Plant Cell Wall

  43. Cell Wall • Found only in plant cells and bacterial cells • It forms the outer most layer of the cell • It protects and supports the plant cell • It is rigid and made up of a carbohydrate called cellulose

  44. The Outer Most Layer of a Plant Cell is the Cell Wall

  45. All cells have a cell membrane!!! • In animal cells, the cell membrane forms the outer layer • In plant and prokaryote cells, the cell wall forms the outer most layer and the cell membrane is just inside of it • Animal CellPlant Cell

  46. Chloroplasts • Large green structures found only in plant cells • Chloroplasts capture energy from sunlight and use it to make food for the plant cell • Chlorophyll in the chloroplasts are responsible for the plant’s green color and is the main pigment used in photosynthesis

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