2.1 Cell Structure

Learning Objectives:

1. Identify names and functions of each part of a cell.

2. Explain how important a nucleus is in a cell.3. Compare tissues, organs, and organ systems.

2.1 Cell Structure

Cell Types – Two Groups:

Prokaryotic Cells Eukaryotic cells

Greek or Latin root words?-karyo means “nucleus”pro- means “before”eu- means “good or well”

2.1 Cell StructureCell Types – Two Groups:

Prokaryotic Cells Eukaryotic cells“Before nucleus” “Good nucleus”

Cells without membrane-bound structures (no nucleus)

Cells with structures that have membranes (have nucleus)

2.1 Cell StructureCell Types – Two Groups:

Prokaryotic Cells Eukaryotic cells

Only found in one-celled (unicellular) organisms, such as bacteria

Found in both unicellular and multicellular organisms, such as protists, fungi, plants, and animals

2.1 Cell Structure

Compare and Contrast the Two Cell Types

What do prokaryotes and eukaryotes have in common? (How do they compare?)

How are they different? (How do they contrast?)

2.1 Cell Structure – Cell Organization

Cell Wall• Function?• Plants, algae, fungi, most bacteria• Made of a carbohydrate called ____________• Can also contain pectin and lignin

ANALOGY?

2.1 Cell Structure – Cell Organization

Cell Membrane• Function?• All cells!• Made of a double layer of _______-like

molecules

ANALOGY?

2.1 Cell Structure – Cell OrganizationCytoplasm – All cellsRoot word alert! Cyto- means _________-Plasm(a) means “form or shape”

• Constantly flows inside cell membrane• What happens in the cytoplasm?

ANALOGY?

2.1 Cell Structure – Cell OrganizationCytoplasm• What structures are found in the cytoplasm?

– Cytoskeleton• Network of protein fibers• Proteins are organic molecules made up of _______

_______.• Function?

– Organelles – only found in ___karyotic cells!– Nucleus (plural: nuclei)

ANALOGIES?

2.1 Cell Structure – Cell OrganizationNucleus – only found in eukaryotic cells• Function?• Separated from cytoplasm by membrane• Contains coded instructions for everything cell does

(in hereditary material called DNA)• During cell division (mitosis or meiosis), the

hereditary material coils tightly around proteins to form chromosomes.

• The nucleolus is a structure within the nucleus.ANALOGY?

2.1 Cell Structure –Energy-Processing Organelles

Chloroplastschloro- means “green”-plast means “formed”

Mitochondria (singular: mitochondrion)mitos- means “thread”chondrion- means “little granule or lump of salt”

2.1 Cell Structure –Energy-Processing Organelles

Chloroplasts• Green organelles found in cytoplasm of plant cells• Capture light energy that is used to make a sugar

called glucose• Glucose molecules store the

captured light energy as chemical energy, which can be used to do work.

2.1 Cell Structure –Energy-Processing Organelles

Mitochondria• Release energy used by the cell• This energy is stored in food (glucose) that the

mitochondria breaks down into carbon dioxide and water.

• What types of cells would have lots of mitochondria?

ANALOGY?

2.1 Cell Structure –Manufacturing Organelles

Ribosomes• Function? To make _______________• Small organelles but not membrane-bound• Some float freely; others are attached to the cell’s

_______________ ________________• Are made in the nucleolus and move out into the

cytoplasm• Take directions from the __________________

ANALOGY?

2.1 Cell Structure –Processing, Transporting, & Storing Organelles

Endoplasmic Reticulum (or ER)• Function? • Extends from nucleus to the __________ _________• Two types:

– ____________ ER is covered with ribosomes.– ____________ ER processes other cellular substances that store energy (e.g., lipids).

ANALOGY?

2.1 Cell Structure –Processing, Transporting, & Storing Organelles

Golgi Bodies• Function: To sort proteins and other cellular

substances and package them into membrane-bound structures called vesicles.– Vesicles deliver these substances to other parts of the cell

or to the cell membrane for release.

• Look like a flattened stack of ______________. Yum!

ANALOGY?

2.1 Cell Structure –Processing, Transporting, & Storing Organelles

Vacuoles• Temporary storage of materials

(water, waste products, food, etc.)

• In plant cells, vacuoles may make up most of the cell’s volume.

ANALOGY?http://sanjit.homework-help.tripod.com/web-page-10-20-2004-science-sector.html

2.1 Cell Structure – Recycling Organelles

Lysosomes• Contain digestive chemicals that break down

__________, ___________, and ___________• Membrane prevents digestive chemicals from leaking

into cytoplasm and destroying cell• When cell dies, this organelle’s membrane

disintegrates to release digestive chemicals that break down all cell parts.

ANALOGY?

2.1 Cell Structure –From Cell to Organism

Cells working together to do one job form a __________.(1)

(1) are organized into __________(2), which are made up of two or more types of (1) that work together.

A group of (2) working together to form a certain function is an ________ ________. (3)

http://www.iq.poquoson.org/2002vasol/5sci/5sci02.htm

Cells come in many shapes and sizes!

Tools for Active Reading

What are some other ways that definitions can be given?

Journal QuestionWe have looked for ways that definitions can be given for new words.

Now you try writing a paragraph that includes a definition!

1. Think of a slang word that an adult might not know (nothing offensive!).

2. Use one example from Table 2.1 as a pattern.3. Write a paragraph that introduces the meaning for

your word.

Pulling It Together - DramaAgent Mildew has just started working for the FBI.

It’s his first day on the job, and he has been given some cells that were collected from a crime scene. He needs your help to figure out if the cells come from a plant, animal, or bacteria.

Develop a skit that shows Agent Mildew learning about what he should look for under the microscope to know what kind of cells he has. All group members must participate.

2.2 Viewing CellsLearning Objectives:

1. Compare the differences between the compound light microscope and the electron microscope.

2. Summarize the discoveries that led to the development of the cell theory.

3. Relate the cell theory to modern biology.

2.2 Viewing CellsCompare the differences between the compound light microscope and the electron microscope.

compound light microscope

Two sets of lenses: eyepiece and objective

Eyepiece may have two tubes (object looks 3D) or one tube (not 3D)

Usually have two to four movable objective lenses

Lenses direct beams of light through a thin object and into your eye

Powerful lenses on some compound microscopes magnify objects up to 2,000x.

How do you calculate total magnification?

2.2 Viewing CellsCompare the differences between the compound light microscope and the electron microscope.

compound light microscope electron microscope

Two sets of lenses: eyepiece and objective Instead of lenses, use a magnetic field to direct beams of electrons

Eyepiece may have two tubes (object looks 3D) or one tube (not 3D).

Show things too small to be seen with other microscopes

Usually have two to four movable objective lenses

Several types: Scanning Electron M (SEM), Transmission Electron M. (TEM), ScanningTunneling M. (STM)

Lenses direct beams of light through a thin object and into your eye.

Images must be photographed or electronically produced.

Powerful lenses on some compound microscopes magnify objects up to 2,000x.

Some can magnify images up to one milliontimes (1,000,000x).

Electron Microscopes

SEM:• Realistic, 3D image• Only the surface of the specimen can be observed

TEM:• 2D image of a thinly-sliced specimen• Show details of cell parts

STM: • Show arrangement of atoms on the surface of a molecule• Hills and valleys of specimen’s surface are mapped.

2.2 Viewing CellsSummarize the discoveries that led to the development of

the cell theory.

1665 – Robert HookeCork = ???

Hooke named them cells.

2.2 Viewing CellsSummarize the discoveries that led to the development of

the cell theory.

1830s – Matthias Schleiden & Theodore Schwann

MS: Studied plant parts. “All plants made of cells.”

TS: Studied animal cells. “All animals made of cells.”

MS + TS: “All living things are made of cells.”

2.2 Viewing CellsSummarize the discoveries that led to the development of

the cell theory.

Late 1800s – Rudolf Virchow“All cells come from other cells.”

2.2 Viewing CellsSummarize the discoveries that led to the development of

the cell theory.

What are the three parts of the Cell Theory?

1.

2.

3.

2.2 Viewing CellsRelate the cell theory to modern biology.

What are the parts of a microscope?Draw a detailed picture of a microscope in your Science

Notebook. Label the following parts:

1. Eyepiece or Ocular (___x)

2. Revolving Nosepiece (“Turret”)

3. Arm

4. Stage

5. Scanning Objective (___x)

6. Low Power Objective (___x)

7. High Power Objective (___x)

8. Light Source

9. Coarse Adjustment Knob

10.Fine Adjustment Knob

11.Stage Clip

12.Base

13.On/Off Switch

14.*Variable Illumination Control

15.*Mechanical Stage Adjustment

Knobs

Friday’s Quiz: Chapter 2, Section 2 (Viewing Cells)

What information would be “fair game”? What questions do you think I might ask you?• Look at “What You’ll Learn” (p. 47), the section assessment (p.

51), “Reading Check” (p. 51)– Similarities and differences between compound light

microscopes and electron microscopes– Calculating magnification– Identifying the parts of a compound microscope– Cell Theory and the discoveries that led to it– Extra credit from p. 48-49 “Visualizing Microscopes”

2.3 Viruses

Learning Objectives:

1. Explain how a virus makes copies of itself.2. Identify the benefits of vaccines.3. Investigate some uses of viruses.

What are viruses?

• Some examples of viruses:– Cold sores– Measles– Chicken pox– Colds– Influenza (“flu”)– HIV/AIDS

What are viruses?

– A virus is a strand of hereditary material surrounded by a protein coating.

– Don’t have a ________________ or other organelles.

– Don’t have a cell ____________________.– Come in lots of shapes.– Cannot be seen with a ___________ microscope ,

so they weren’t discovered until the invention of the _______________ microscope.

How do viruses multiply?

• Crystallized forms of some viruses can be stored for many years. They can reproduce quickly if they enter an organism.

• Cannot reproduce on their own• Need help of a living cell: HOST CELL• Once virus is inside host cell, can be active or

become latent (inactive stage).

How do viruses multiply?

Active Viruses vs. Latent Viruses

• Active viruses enter host cell and cause cell to make new viruses. This destroys the host cell.

How do viruses multiply?

How do viruses multiply?Active Viruses vs. Latent VirusesLatent Viruses• Virus enter host cell; hereditary material becomes part

of the cell’s hereditary material.• Does not immediately make new viruses or destroy host

cell.• As host cell reproduces, viral DNA is copied.• A virus can be latent for many years before being

activated by certain conditions (inside or outside body).• Example: Cold sore

How do viruses affect organisms?

Fighting Viruses

The First Vaccine

Treating and Preventing Viral Disease

Research with Viruses