Cell Structure and Function

Chapter 7

Prior Knowledge

• All Living Things are Composed of ____Cells___.

Influential Scientists• Robert Hooke – Looked at Cork Cells,

Called the little chambers “cells”• Anton van Leeuwenhoek – Simple

Microscope, Saw Small Living Organisms in the Water and Called them “animalcules”

• Matthias Schleiden – Plant Cells• Theodor Schwann – Animal Cells• Rudolph Virchow – Cells Come From the

Division of Existing Cells

The Cell Theory

1. All Living Things are Composed of Cells

2. Cells are the basic units of structure and function in living things.

3. New Cells Come From Existing Cells

Prokaryote vs. Eukaryote

• Prokaryote - have cell membranes and cytoplasm but do not contain nuclei. – Simple Cells (Unicellular)– All bacteria are prokaryotes.

• Eukaryote- Contain nuclei. Also have a cell membrane, cytoplasm, and specialized organelles.– Complex Cells– All plants, animals, fungi, and many

microorganisms, are eukaryotes.– Eukaryote cells are much larger than prokaryote cells

Fig. 4.5

Fig. 4.6a

Fig. 4.6b

Vocabulary

3 Components of the Cell TheoryRobert HookeAnton von LeeuwenhoekSchleiden vs. SchwannRudolf VirchowProkaryote vs. EukaryoteAnimal vs. Plant Cell

Vocabulary

Nucleus/NucleolusChloroplast/ChlorophyllMitochondriaChromosome vs. ChromatidCell Wall vs. Cell MembraneRibosomesGolgi Apparatus/Endoplasmic ReticulumVacuolesLysosomesCilia/Flagella

Cell Structure & Organelles

Organelles- specialized structure that performs important cellular functions within a eukaryotic cell

Cell Structure

• Cell Walls provide extra support and protection

• Plants, bacteria, algae, and fungi have Cell Walls

* In plants, cell walls are composed of cellulose

* Animal Cells

DO NOT

have

CELL WALLS

Chromosomes

Also called chromatin.

Composed of DNA

Found in the nucleus of eukaryotic cells and in the nucleoid region of prokaryotic cells.

Chloroplasts

• Found in plants, some algae, and some bacteria• Converts the sun’s light energy into chemical

energy during photosynthesis• Contains chlorophyll (green pigment)

Cilia• Small Hairlike Projections• Found in Eukaryotic Cells• Help unicellular organisms to move.• Also helps to move materials past other cells.

Cytoplasm• A thick solution that fills each cell and is

enclosed by the cell membrane. • Mainly composed of water, salts, and proteins. • In eukaryotic cells, the cytoplasm includes all

of the material inside the cell and outside of the nucleus.

Endoplasmic Reticulum• Organelle where components of cell

membrane are made and proteins are modified

– Rough E.R.• studded with ribosomes

• Either exports proteins from cell or sends them to the cytoplasm

– Smooth E.R.• No ribosomes

• Helps in lipid production and breakdown of toxic substances

The Endoplasmic Reticulum (E.R.)

Other Cell Structures

• Cilia (cilium): short hair-like projection; produces movement

in many

cells

• Flagella (flagellum): whip-like structure on some cells that is used for movement

Cilia Flagella

Golgi Apparatus• Vesicles (small transport sacs) carry proteins

from Rough E.R. to Golgi for processing/modification.

• Attaches carbohydrates and lipids to proteins, and the new proteins are “packaged” in new vesicles.

Lysosomes

• Small organelles filled with digestive enzymes– They can break down

needed materials, used cell parts, pathogens, and even play a role in development

• They destroy tissue to create fingers because our hands begin as solid structures!

Mitochondria

• cell organelle that releases energy from stored food molecules.

• Involved in cellular respiration- turning carbohydrates into energy.

• Cells that need more energy have more mitochondria

• Nucleus– Stores hereditary info in the form of DNA

• DNA is inside chromatin, a granular material that condenses into chromosomes during cell division

– Houses a nucleolus – small, dense region within responsible for the assembly of ribosomes

– Surrounded by a nuclear envelope

“The Control Center”

The Nucleus

Cell Membrane

• Outside of Cell

• Semi-permeable

• May have an outer coating of a cell wall

• Contained in all cells – prokaryotic and eukaryotic

• “Bodyguard” – Controls what goes in and out.

Ribosomes

• Make proteins

• Made up of rRNA (ribosomal RNA) and protein

• Can be free-roaming in cytoplasm or located on the Rough Endoplasmic Reticulum

Vacuole

Found in all eukaryotic cells

Large Central Vacuole in plants and numerous small vacuoles in animal cells.

Storage of Materials

Cytoskeleton• Network of protein filaments that helps

the cell maintain shape and is involved in cell movement. Contains 2 parts:

– Microfilaments – long, thin strands

that help a cell move and provide a

tough framework for the cell

– Microtubules – hollow tubes

by which organelles can move from

one part of a cell to another

Centrioles

• Tiny structures located in the cytoplasm of animal cells near the nuclear envelope.

• Play a role in cell division.

So Where Did These Eukaryotes Come From?

• Mitochondria and Chloroplasts contain their own DNA genetic information separate from the cells DNA.

• So, Scientists have done research and come up with a Theory…

• The ENDOSYMBIOTIC THEORY

The Endosymbiotic Theory

• The first eukaryotes may have formed from one bacteria engulfing another without killing it.

• Later a symbiotic relationship was formed

Stop and Think…

• Are plant and animal cells prokaryotic or eukaryotic?

• How does the meaning of prokaryotic or eukaryotic help you answer this question?

• Give one or two examples that help you answer this question.

Plant Cells

• Cell wall located outside the cell membrane. Cell wall is made from cellulose fibers, and it is used for support & protection

• Contains one large vacuole that contains water. Vacuole full = plant is rigid. Vacuole loses water = plant wilts

• Chloroplasts = contain chlorophyll, which captures sunlight & converts it into energy

Plant Cell

Build a plant cell

Animal Cells

• Have no cell wall

• NO chlorophyll

• CANNOT make their own food

So Plant and Animal Cells

are…

• Both eukaryotic cells- Both have nucleuses, organelles, cell membranes, cytoplasm

Plant and animal cell differences

• Plant Cells

• Cell wall

• Chloroplasts

• Large central vacuole

• No centrioles

Animal Cells• Have centrioles• No cell wall• No chloroplasts• No large

central vacuole

Construct a cell

Diversity of Life

• Unicellular organisms- A single-celled organism

• Unicellular organisms include both prokaryotes and eukaryotes.

A prokaryotic unicellular organismA eukaryotic unicellular organism (paramecium)

Contractile Vacuole

• Multicellular organisms- organisms that have more than one cell working together. Have cell specialization

• Cell specialization- specific roles for different types of cells

Diversity of Life Continued…

Levels of Organization

• Cells- the basic unit of life• Tissues- a group of similar cells that perform

a particular function • Organs- many groups of tissues work

together • Organ Systems- A group of organs that

work together to perform a specific function • Organism- An entire living being made up of

organ systems

Test your Knowledge…

Using the following terms, place the levels of organizationin the correct order of the chart.

-Stomach - Digestive System-Smooth muscle tissue -Muscle Cell

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