Unit A – Cells and Systems

Chapter 1 - Cells

Cells – Key Ideas Living things share many characteristics Living things share many characteristics All living things are made of up of one or more cells All living things are made of up of one or more cells Animal and plant cells are similar in some ways and different in others Animal and plant cells are similar in some ways and different in others Technology helps us learn about the structure and function of cells Technology helps us learn about the structure and function of cells Substances move in and out of cells Substances move in and out of cells 3

1.1 – Characteristics of Living Things How do you know if something is alive?

Organism – any individual living thing Before something can be classified as an organism, it must show all of the characteristics of living things (see Table 1 p5) 5

Characteristics of Living Things Living things are composed of cells Living things are composed of cells Living things reproduce, grow, and repair themselves. Living things reproduce, grow, and repair themselves. Living things require energy Living things require energy Living things respond to their environment Living things respond to their environment Living things have a life span Living things have a life span Living things produce waste Living things produce waste 6

Why isn’t a Solar Calculator Alive? What characteristic’s of life does it have? 7

Is a Star Fish Living? What characteristics does a star fish have? Require energy? Respond to environment? Reproduce? Grow? And repair? Have a lifespan? Produce waste? Is it made of cells? 8

Cell Theory Cells are the basic unit of all living things Cells are the basic unit of all living things The Cell Theory: The Cell Theory: All living things are composed of one or more cells All living things are composed of one or more cells All new cells arise only from cells that already exist (new cells come from old cells) All new cells arise only from cells that already exist (new cells come from old cells) 9

1.2 – Using a Microscope Be careful…please

The Parts of a Microscope 11

12

Microscope – Field of View The Field of View – is the circle of light you see when you look through the eyepiece of a microscope The Field of View – is the circle of light you see when you look through the eyepiece of a microscope Ratio = magnification of high-power lens/magnification of low-power lens Ratio = magnification of high-power lens/magnification of low-power lens Diameter of field (high power) = diameter of field (low power)/ratio Diameter of field (high power) = diameter of field (low power)/ratio 13

1.3 – Plant and Animal Cells What’s the Difference?

Plant and Animal Cells The cells of all plants and the cells of all animals have many structures in common The cells of all plants and the cells of all animals have many structures in common Using a microscope it is easy to tell between plant and animal cell but it is hard to tell which plant cell came from which plant and which plant cell came from which animal Using a microscope it is easy to tell between plant and animal cell but it is hard to tell which plant cell came from which plant and which plant cell came from which animal 15

Animal Cell Structures 16

The Nucleus The NUCLEUS is the control centre. It directs all of the cell’s activities. The NUCLEUS is the control centre. It directs all of the cell’s activities. In plant and animal cells, the nucleus is surrounded by a membrane. In plant and animal cells, the nucleus is surrounded by a membrane. Cells with a nuclear membrane are known as EUKARYOTIC CELLS Cells with a nuclear membrane are known as EUKARYOTIC CELLS 17

The Nucleus In some one-celled organisms, such as bacteria, the nucleus is not surrounded by a membrane. These cells are known as PROKARYOTIC cells In some one-celled organisms, such as bacteria, the nucleus is not surrounded by a membrane. These cells are known as PROKARYOTIC cells 18

The Nucleus EukaryoticProkaryotic 19

Chromosomes inside the nucleus Contain DNA or genetic information, which holds “construction plans” for all the pieces of the cell. This genetic information is duplicated and passed on to other identical cells. 20

Cell Membrane holds the contents of the cell in place Controls the movement of materials (nutrients and waste) into and out of the cell. consists of a double layer of fat molecules. 21

Cytoplasm watery fluid that contains everything inside the cell membrane and outside the nucleus. Allows materials to be transported quickly Stores wastes until they can be disposed of 22

Vacuole Used to store water and nutrients Also used to store waste and move excess water out of the cell 23

Animal Cell - Movement Some animal cells may have special structures that help them move in their environment FlagellumCilia 24

The Flagellum Flagellum- a whip-like tail that helps a cell to move 25

Cilia Cilia- tiny hairs that work to move a cell or the fluid around a cell 26

Plant Cell Structures 27

Vacuole Just like animal cells except usually much larger 28

Cell Wall Provides protection and support to the plant cell 29

Chloroplasts Are the food factories of the cell Contain many molecules of a green pigment called chlorophyll Chlorophyll is necessary for photosynthesis 30

1.4-Technological Advances of the Microscope

The Single – Lens Microscope Anton van Leeuwenhoek’s (1660’s) single lens microscope magnified things 10 x’s (made objects 10 times bigger than their normal size) 32

The Compound Light Microscope Single lens were not enough for scientists who wanted to see things in greater detail Eventually a second lens was added to magnify the image ( 10x’s X 10 x’s = 100 x’s) Light microscope is limited to about 2000 x’s (image becomes too blurry) Greater magnification is needed to see the details of a human cell 33

Compound Light Microscope 34

The Transmission Electron Microscope Are capable of x’s magnification Use electrons instead of light Limitations Must use extremely thin specimens Only dead cells can be observed 35

The Transmission Electron Microscope 36

The Scanning Electron Microscope It uses electrons that are deflected of a specimen to create a digital three-dimensional image Because it uses only reflected electrons the thickness of the specimen does not matter Limitations Only the outside of the specimen can be seen Cannot magnify as high as the transmission electron microscope 37

The Scanning Electron Microscope 38

1.6 – Parts of a Cell Seen with an Electron Microscope

Organelles organelle -a tiny structure within the cytoplasm of a cell; specialized to carry out a function 40

Mitochondria: Energy Production mitochondria (sing. mitochondrion) - circular or rod-shaped organelles that provide the cells with energy through a process called cellular respiration. 41

Cellular Respiration cellular respiration - a process in which mitochondria release energy by combining sugar molecules with oxygen to form carbon dioxide and water Sugar + O 2 CO 2 + ENERGY 42

Ribosomes: Protein Manufacturing ribosome - a very small organelle that uses information from the nucleus and molecules from the cytoplasm to produce proteins Proteins are needed for Cell growth RepairReproduction 43

Endoplasmic Reticulum: Material Transport endoplasmic reticulum (ER) - a cell structure that consists of a series of folded membranes that act as canals to carry materials through the cytoplasm Rough – with ribosomes (proteins) Smooth – without ribosomes (lipids (fats)) 44

The Golgi Apparatus: Protein Storage Golgi apparatus - an organelle that stores proteins and puts them into packages, called vesicles 45

Lysosomes: Recycling lysosome - an organelle formed by the Golgi apparatus to control and clean the cytoplasm; contains special proteins used to break down large molecules into smaller molecules; also destroys damaged or worn-out cells Also destroy harmful substances and bacteria that enter the cell. 46

1.7 – Cells in Their Environment

Cell Membranes Cells allow some materials to enter and leave but not others Permeable = permitting passage Impermeable = not permitting passage The cell membrane is said to be selectively permeable 48

Selectively Permeable A membrane that allows certain substances to enter or leave 49

Diffusion DIFFUSION- the movement of molecules from an area of high concentration to an area of low concentration Molecules are constantly in motion, when they collide, they bounce off each other which causes the molecules to spread out 50

Diffusion and Cells Diffusion is one of the ways that substances move into and out of cells Substances that the cell needs (oxygen) are in higher concentration outside the cell and then diffuse across the membrane into the lower concentration inside the cell Substances the cell doesn’t need (waste – carbon dioxide) tend to get more concentrated inside the cell, so they will diffuse across the cell membrane to the lower concentration 51

1.8 - Osmosis

Osmosis Osmosis - is the diffusion of water across a selectively permeable membrane The direction of water movement depends on the concentration of water inside the cell compared with the concentration outside the cell 53

A Model of Osmosis (see p.25 fig. 2) 54

Cells in Solutions of Different Concentrations 55

Turgor Pressure (see p.27) Turgor Pressure - the pressure created inside a plant cell when water molecules enter the cell by osmosis; the water fills the vacuole and cytoplasm, causing them to swell up and push against the cell wall 56

1.11 – Career Profile: Modellers