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Section 7-1. Are All Cells Alike?. All living things are made up of cells. Some organisms are composed of only one cell. Other organisms are made up of many cells. 1. What are the advantages of a one-celled organism? 2. What are the advantages of an organism that is made up of many cells?.

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are all cells alike

Section 7-1

Are All Cells Alike?
  • All living things are made up of cells. Some organisms are composed of only one cell. Other organisms are made up of many cells.
  • 1. What are the advantages of a one-celled organism?
  • 2. What are the advantages of an organism that is made up of many cells?
slide2

Section Outline

Section 7-1

  • 7–1 Life Is Cellular

A. The Discovery of the Cell

1. Microscopes

2. The Cell Theory

B. Exploring the Cell

C. Prokaryotes and Eukaryotes

1. Prokaryotes

2. Eukaryotes

slide3

Section 7-1

Discovery of the Cell

Robert Hooke – 1665 – named cell

Leeuwenhoek – 1674 – observed living microorganisms

Schleiden – 1838 – all plants made of cells

Schwann – 1839 – all animals made of cells

Virchow – 1855 - all cells come from cells

slide4

Section 7-1

Exploring the Cell

Microscopy

- the history of cytology is tied to the development of the microscope.

Light microscopes - pass light through the specimen

- can magnify up to about 1200x

- easy to prepare specimens and can look at living specimens.

slide5

Section 7-1

2. Transmission Electron Microscope

- send a beam of electrons through the specimen

- focused with magnets

- resolving power up to 100,000(+)x

- specimens have to be prepared and can’t be alive

slide6

Section 7-1

3. Scanning Electron Microscope

- bounce electrons off the surface of the specimen

- gives detailed three-dimensional images of the surface of the specimen

slide7

Section 7-1

  • Cell Theory
  • Cells are the basic structural and functional units of life
  • Under the conditions present on Earth today all cells come from other cells.
  • All living things are composed of cells
slide8

Section 7-1

  • Prokaryotes-cells that have genetic material that is not contained in the nucleus. Generally smaller and more simple than eukaryotes.
  • Bacteria are prokaryotes.
  • Eukaryotes-contains a nucleus in which their genetic material is separated from the rest of the cell. Plants, animals, fungi, and protists are Eukaryotes.
slide9

Cell membrane

Cytoplasm

Cell membrane

Cytoplasm

Prokaryotic and Eukaryotic Cells

Section 7-1

Prokaryotic Cell

Nucleus

Eukaryotic Cell

Organelles

slide10

Prokaryotes

Eukaryotes

Nucleus

Endoplasmic reticulum

Golgi apparatus

Lysosomes

Vacuoles

Mitochondria

Cytoskeleton

Cell membrane

Contain DNA

Venn Diagram

Section 7-1

division of labor

Section 7-2

Division of Labor
  • A cell is made up of many parts with different functions that work together. Similarly, the parts of a computer work together to carry out different functions.
  • Working with a partner, answer the following questions.
  • 1. What are some of the different parts of a computer? What are the functions of these computer parts?
  • 2. How do the functions of these computer parts correspond to the functions of certain cell parts?
slide12

Section Outline

Section 7-2

  • 7–2 Eukaryotic Cell Structure
  • A. Comparing the Cell to a Factory
  • B. Nucleus
  • C. Ribosomes
  • D. Endoplasmic Reticulum
  • E. Golgi Apparatus
  • F. Lysosomes
  • G. Vacuoles
  • H. Mitochondria and Chloroplasts

1. Mitochondria

2. Chloroplasts

  • 3. Organelle DNA
  • I. Cytoskeleton
slide13

Section 7-2

  • Nucleus
  • “control center” of the cell
  • Contains the chromosomes on which the genes are located
    • Fine threads called chromatin in nondividing cells
    • Condense into visible chromosomes during cell division
  • Nuclear membrane has two parallel membranes with nuclear pores penetrating them
  • Nuclear pores allow mRNA to leave the nucleus to go to the cytoplasm
  • Also contains the nucleolus where ribosomal subunits are produced
slide14

Section 7-2

Ribosomes

- sites of protein synthesis – where amino acids are joined

- many are attached to Rough ER; others are free in the cytoplasm

- composed of RNA and protein

- attached ribosomes make proteins for export

- free ribosomes make proteins for intracellular use

slide15

Section 7-2

Endoplasmic Reticulum

- membranous-walled canals and flat sacs that extend from the plasma membrane to the nucleus

- important in the synthesis, modification, and movement of materials within the cell

A. Rough Endoplasmic Reticulum

- has ribosomes attached to its’ surface

- ribosomes make proteins which move into the cisternae of the ER and are transported toward the Golgi apparatus

slide16

Section 7-2

B. Smooth Endoplasmic Reticulum

- lacks ribosomes

- transports, synthesizes, and chemically modifies small molecules

- synthesizes certain lipids and carbohydrates and creates membranes for use throughout the cell

slide17

Section 7-2

Golgi Apparatus

- series of flattened membranous sacs that modify protein products of the rough endoplasmic reticulum

- final products are packaged in vesicles which can then be moved to the cell membrane for export

- some of these vesicles remain in the cell as lysosomes

- can also give rise to new membrane structures for the cell

slide18

Section 7-2

Lysosomes

- digestive system of the cell

- membranous sacs which pinch off the Golgi apparatus

- contain hydrolytic enzymes which digest particles or large molecules that enter them

- also responsible for digesting unneeded or unhealthy cells and cell parts

slide20

Section 7-2

Vacuoles

- saclike structures used for storage within the cell

- stores water, salts, proteins, and carbohydrates

- discerning feature in many plant cells that is

large and liquid filled

makes possible for plants to support heavy

structures such as leaves and flowers

- in many cases the vacuole is controls the water content of the cell which maintains homeostasis

slide21

Section 7-2

Mitochondria

- “power plants” of cells

- double membraned organelle with fluid between the membranes

- lots of enzymes attached to both membranes

- enzymes catalyze oxidation reactions of cellular respiration and capture the energy of sugars in the bonds of ATP

- provide 95% of the cell’s energy

- contain their own ribosomes and DNA and can replicate themselves

slide22

Section 7-2

Chloroplasts

- capture the energy of the sunlight and convert it into the chemical energy of sugar in a process called photosynthesis

- double membraned organelle like mitochondria

- also contain their own DNA

- contain large stacks of membranes containing chlorophyll

slide23

Section 7-2

Cytoskeleton

Internal support framework made up of rigid, rodlike proteins that support the cell and allow movement and mechanisms that can move the cell or its parts

Acts as both muscle and skeleton for cell

Cell Fibers

- form a three-dimensional support framework

- support endoplasmic reticulum, mitochondria, and free ribosomes

slide24

Section 7-2

1. Microfilaments – smallest fibers

- cellular muscles that provide for movement

2. Intermediate filaments – form much of the support network of the cell

3. Microtubules – maintain cell shape and move things within the cell made up of proteins known as tublin

4. Tubulin is also used to make structures in animal cells known as the centrioles. These aid in organization during cell division

slide25

Cell membrane

Endoplasmic

reticulum

Microtubule

Microfilament

Ribosomes

Mitochondrion

Figure 7-11 Cytoskeleton

Section 7-2

slide26

Smooth endoplasmic

reticulum

Vacuole

Ribosome

(free)

Chloroplast

Ribosome

(attached)

Cell

Membrane

Nuclear

envelope

Cell wall

Nucleolus

Golgi apparatus

Nucleus

Mitochondrion

Rough endoplasmic reticulum

Figure 7-5 Plant and Animal Cells

Section 7-2

Plant Cell

slide27

Ribosome

(attached)

Ribosome

(free)

Nucleolus

Nucleus

Cell

Membrane

Nuclear

envelope

Mitochondrion

Smooth

endoplasmic

reticulum

Rough

endoplasmic

reticulum

Centrioles

Golgi apparatus

Figure 7-5 Plant and Animal Cells

Section 7-2

Animal Cell

slide28

Animal Cells

Plant Cells

Cell membrane

Ribosomes

Nucleus

Endoplasmic reticulum

Golgi apparatus

Lysosomes

Vacuoles

Mitochondria

Cytoskeleton

Cell Wall

Chloroplasts

Centrioles

Venn Diagram

Section 7-2

in or out

Section 7-3

In or Out?
  • How is a window screen similar to a cell membrane? Read on to find out.
  • 1. What are some things that can pass through a window screen?
  • 2. What are some things that cannot pass through a window screen? Why is it important to keep these things from moving through the screen?
  • 3. The cell is surrounded by a cell membrane, which regulates what enters and leaves the cell. Why is it important to regulate what moves into and out of a cell?
slide30

Section Outline

Section 7-3

  • 7–3 Cell Boundaries

A. Cell Membrane

B. Cell Walls

C. Diffusion Through Cell Boundaries

1. Measuring Concentration

2. Diffusion

D. Osmosis

1. How Osmosis Works

2. Osmotic Pressure

E. Facilitated Diffusion

F. Active Transport

1. Molecular Transport

2. Endocytosis and Exocytosis

slide31

Section 7-3

  • Cell Membrane
  • All of the membranes of the cell have similar structure.
  • Plasma Membrane
  • -Fluid Mosaic Model – developed by Singer and Nicolson
  • -Molecules are arranged in a sheet
  • -Molecules are held together by chemical attractions between them and their interactions with water.
  • -Primary structure is a double layer of phospholipid molecules

Phosphate heads are hydrophilic; tails are hydrophobic

slide32

Section 7-3

-Cholesterol molecules within the membrane help it function at body temperatures.

-Because the hydrophobic tails make-up most of the membrane, water soluble materials can’t pass through the membrane.

-Channel proteins which are embedded in the membrane help control movement of materials into and out of the cell

-Glycoproteins have carbohydrates attached and serve as cell surface identifiers

-Receptor proteins react to specific chemicals and cause changes within the cell.

-Overall, the plasma membrane is selectively permeable.

  • Cell Membrane-cont.
slide33

Outside

of cell

Carbohydrate

chains

Proteins

Cell

membrane

Inside

of cell

(cytoplasm)

Protein

channel

Lipid bilayer

Figure 7-12 The Structure of the Cell Membrane

Section 7-3

slide34

Section 7-3

-Provide support and protection for the cell.

-Most are composed of fibers of carbohydrate and protein

-Plant cell walls are mostly cellulose

  • Cell Walls
slide36

Section 7-3

Passive Transport Processes

-Do not require energy expenditure by the cell

-Second Law of Thermodynamics

Diffusion

- movement of particles from an area of high concentration to an area of low concentration down a concentration gradient.

- continues until equilibrium is reached

- membrane channels are pores through which specific ions or small water-soluble molecules can pass

- gases also move by diffusion

  • Movement Through the Cell Boundaries
slide38

Section 7-3

Passive Transport Processes cont.

Osmosis

- diffusion of water through a selectively permeable membrane

- water moves down it’s concentration gradient – this often means it is moving toward higher salt concentrations

- Osmotic Pressure – water pressure that develops as a result of osmosis

- healthy cells are normally in an environment where the net movement of water is 0.

slide39

Section 7-3

Passive Transport Processes cont.

Osmosis cont.

- Tonicity – ability of a solution to move water in/out of a cell and change its shape

a. Isotonic – osmotic pressure is = inside and outside

b. Hypertonic – osmotic pressure is greater than within the cell – water moves out of cell causing crenation

c. Hypotonic – osmotic pressure is less than within the cell – water moves into the cell causing lysis.

slide41

Figure Osmosis

Section 7-3

slide42

Osmosis Video

Section 7-3

slide43

Glucose

molecules

High

Concentration

Cell

Membrane

Protein

channel

Low

Concentration

Facilitated Diffusion

Section 7-3

  • Facilitated Diffusion

- movement through carrier proteins along the concentration gradient

- rate is dependent on concentration gradient and availability of carrier molecules

slide44

Molecule to

be carried

Energy

Molecule

being carried

Section 7-3

-cell uses metabolic energy to move materials

1. Molecular Transport

- carrier-mediated process that moves substances against their concentration gradients

- opposite of diffusion

- substances are moved by pumps which use ATP to change shape and move their cargos

- carrier proteins bind to cargo, change shape, and release the cargo

  • Active Transport
slide46

Section 7-3

2. Endocytosis and Exocytosis

- allow things to enter and leave a cell without actually passing through the plasma membrane.

A. Endocytosis – plasma membrane traps some extracellular material and moves it to the interior in a vesicle.

- Phagocytosis – large particles are engulfed within a vesicle that then fuses with lysosomes to digest particles

- Pinocytosis – fluid and the substances dissolved in it enter the cell

  • Active Transport (cont.)
from simple to more complex

Section 7-4

From Simple to More Complex
  • Many multicellular organisms have structures called organs that have a specific function and work with other organs. Working together, these organs carry out the life processes of the entire organism.
slide49

Section 7-4

  • 1. Some activities cannot be performed by only one person, but need a team of people. What type of activity requires a team of people to work together in order to complete a task?
  • 2. What do you think are some characteristics of a successful team?
  • 3. How is a multicellular organism similar to a successful team?
slide50

Section Outline

Section 7-4

  • 7–4 The Diversity of Cellular Life

A. Unicellular Organisms

B. Multicellular Organisms

1. Specialized Animal Cells

2. Specialized Plant Cells

C. Levels of Organization

1. Tissues

2. Organs

3. Organ Systems

slide51

Section 7-4

  • Unicellular Organisms
  • Single-celled organisms that grow, respond to the environment, transform energy, and reproduce
  • Multicellular Organisms
  • Organisms that are made up of many cells that are developed for different tasks through a process called cell specialization
slide52

Muscle cell

Smooth muscle tissue

Stomach

Digestive system

Levels of Organization

Section 7-4

  • Levels of Organization
  • 1. Cells
  • 2. Tissues
  • 3. Organs
  • 4. Organ Systems
section 1 answers

Interest Grabber Answers

Section 1 Answers
  • 1. What are the advantages of a one-celled organism?
  • A one-celled organism has simpler needs and can respond immediately to its environment because its entire cell is immersed in its environment.
  • 2. What are the advantages of an organism that is made up of many cells?
  • In a multicellular organism, different jobs are divided among different groups of cells that work together. Also, a multicellular organism can continue to survive even if it loses some of its cells.
section 2 answers

Interest Grabber Answers

Section 2 Answers
  • Working with a partner, answer the following questions.
  • 1. What are some of the different parts of a computer? What are the functions of these computer parts?
  • Answers may include: monitor (interfaces with the computer’s environment), software (instructions for how to carry out different jobs), CPU (directs the computer's activities), recycle bin or trash can (storage area for wastes), and so on.
  • 2. How do the functions of these computer parts correspond to the functions of certain cell parts?
  • Students should try to link the functions they described in question 1 to the functions of the different cell structures. The cell needs a way to interface with its environment (cell membrane), instructions for carrying out different jobs (DNA), and a CPU to direct the cell’s activities (nucleus).
section 3 answers

Interest Grabber Answers

Section 3 Answers
  • 1. What are some things that can pass through a window screen?
  • Answers may include air, fine dust, and rainwater.
  • 2. What are some things that cannot pass through a window screen? Why is it important to keep these things from moving through the screen?
  • Insects, leaves, and other matter that may fall from trees. The screen keeps out annoying insects and objects that may bring dirt into the home.
  • 3. The cell is surrounded by a cell membrane, which regulates what enters and leaves the cell. Why is it important to regulate what moves into and out of a cell?
  • Materials such as oxygen and food that are needed by the cell have to be able to get inside the cell. At the same time, excess materials have to leave the cell.
section 4 answers

Interest Grabber Answers

Section 4 Answers
  • 1. Some activities cannot be performed by only one person, but need a team of people. What type of activity requires a team of people to work together in order to complete a task?
  • Answers might include building a human pyramid or constructing an arch out of blocks.
  • 2. What do you think are some characteristics of a successful team?
  • Divide up jobs and cooperate well with one another.
  • 3. How is a multicellular organism similar to a successful team?
  • The functions of the organism are divided up among its parts (organs and organ systems). All the parts cooperate to carry out all the functions of the whole organism.
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