Cells The smallest unit of life

Which of these is the smallest object? 1.Human cell 2.Protein molecule 3.Virus 4.Bacteria 5.Amino acid

Prokaryotic organisms lack a nucleus in their cells. Which of these organisms is prokaryotic? 1.Plants 2.Fungi 3.Protists (such as Amoeba and Paramecium) 4.Bacteria

Which of these objects can be seen with the aid of an ordinary student microscope? 1.Human cell 2.Virus 3.Protein molecule 4.Oxygen atom

Which of these is made up of cells? 1.Animals 2.Plants 3.Fungi 4.Bacteria 5.Only animals and plants 6.All of these

Discovering the Cell Robert Hooke

Anton van Leeuwenhoek - late 17th, early 18th centuries

1839 – Cell Theory is proposed independently by Theodore Schwann and Matthias Jakob Schleiden.

Cell Theory: The cell is the fundamental structure of all living things. All living things are made of cells. Cells arise from pre-existing cells through cell division.

Ernst Ruska

Light micrograph Scanning electron micrograph Paramecium

Cell Membrane Transmission electron micrograph Scanning electron micrograph

Which of these can be seen with an electron microscope but not a light microscope? 1.Human cells 2.Bacteria 3.Protein molecules 4.Amino acids

Discuss and write down your ideas: How did the invention of the microscope change the human view of the world? How did the invention of the electron microscope change our understanding of cells? WORKTOGETHERWORKTOGETHER

Prokaryotic Cells

Prokaryotic Features No membrane-bound organelles, such as a nucleus. DNA in one large ring-shaped chromosome An enormous variety of metabolic pathways. Highly successful and adaptable.

External structure Coccus (spherical) Spirillus (spiral)Bacillus (rod-shaped)

Internal Structure Figure 4-20a Biology: Life on Earth 8/e ©2008 Pearson Prentice Hall, Inc. chromosome (nucleoid region) plasmid (DNA) cytosol plasma membrane cell wall capsule or slime layer prokaryotic flagellum food granule ribosomes pili

True or False: A virus is a kind of bacteria. 1.True 2.False

Viruses A virus is usually not considered living. A virus consists only of a protein coat (sometimes with a lipid outer layer) and a piece of genetic material (DNA or RNA).

Bacteria vs. Virus FeaturesBacteriaVirus Reproduces independently? Has genetic material? Has cell membrane? Has metabolism? Living? YesNo Yes No Yes

Which of these does a bacteria NOT have? 1.DNA 2.Cell membrane 3.Nucleus 4.Bacteria have none of these.

Eukaryotic Cells

Eukaryotic Features Cells contain membrane-bound organelles. Nucleus holds multiple strands of DNA, which condense into chromosomes during cell division. May be single-celled or multi-cellular organisms.

Figure 4-3 Biology: Life on Earth 8/e ©2008 Pearson Prentice Hall, Inc. smooth endoplasmic reticulum mitochondrion cytosol lysosome ribosomes on rough ER centriole Golgi apparatus vesicle nuclear pore nuclear envelope chromatin (DNA) nucleolus plasma membrane rough endoplasmic reticulum free ribosome nucleus Animal cell

Figure 4-9a Biology: Life on Earth 8/e ©2008 Pearson Prentice Hall, Inc. nuclear pores nuclear envelope chromatin nucleolus Nucleus

Figure 4-12 Biology: Life on Earth 8/e ©2008 Pearson Prentice Hall, Inc. vesicles rough ER smooth ER ribosomes Endoplasmic Reticulum

Figure 4-13 Biology: Life on Earth 8/e ©2008 Pearson Prentice Hall, Inc. Protein-carrying vesicles from ER merge with Golgi apparatus Golgi apparatus Vesicles carrying modified protein leave Golgi apparatus Golgi Apparatus

Figure 4-14 Biology: Life on Earth 8/e ©2008 Pearson Prentice Hall, Inc. 1 A protein is synthesized in the rough ER. 5 Vesicles merge with the plasma membrane and release protein by exocytosis. 4 Completed protein is packaged into vesicles. 3 Vesicles fuse with Golgi. The protein may be altered and finished. 2 Protein is packaged into vesicles and travels to Golgi apparatus. ER and Golgi function

A cell that produces a lot of protein must have an extensive: 1.Nucleus 2.Rough ER 3.Smooth ER 4.Golgi apparatus

Proteins are packaged for delivery by the: 1.Nucleus 2.Rough ER 3.Golgi apparatus

Discuss and summarize in your own words the roles of: the cell nucleus the rough ER the Golgi complex WORKTOGETHERWORKTOGETHER

Lysosomes

ER, Golgi, & Lysosome Function after Phagocytosis Figure 4-15 Biology: Life on Earth 8/e ©2008 Pearson Prentice Hall, Inc. 1 Enzymes are synthesized in ER. plasma membrane waste ER digestive enzymes food vacuole lysosome Golgi nucleus 4 Lysosome fuses with food vacuole and enzymes digest food. 3 Lysosomes bud from Golgi. 2 Golgi modifies enzymes.

Mitochondrion cristae outer membrane inner membrane intermembrane compartment 0.2 micrometer matrix

White blood cells must locate, engulf, and destroy many foreign particles. Which organelle will help them most in this task? 1.Nucleus 2.Lysosome 3.Endoplasmic reticulum 4.Golgi bodies

Discuss and summarize in your own words the roles of the lysosome and the mitochondrion in animal cell nutrition. WORKTOGETHERWORKTOGETHER

Figure 4-3 Biology: Life on Earth 8/e ©2008 Pearson Prentice Hall, Inc. smooth endoplasmic reticulum mitochondrion cytosol lysosome ribosomes on rough ER centriole Golgi apparatus vesicle nuclear pore nuclear envelope chromatin (DNA) nucleolus plasma membrane rough endoplasmic reticulum free ribosome nucleus Animal cell

True or false: Plant cells are much more primitive than animal cells and have far fewer types of organelles. 1.True 2.False

Plant cells are: 1.Eukaryotic 2.Prokaryotic

Plant Cell - same organelles as an animal cell, plus a few more ribosomesfree ribosome nuclear pore nuclear envelope chromatin (DNA) nucleolus nucleus smooth endoplasmic reticulum vesicle rough endoplasmic reticulum Golgi apparatus choloroplast mitochondrionplastid plasma membrane plasmodesma cell wall central vacuole cytosol

Cell Wall secondary cell wall middle lamella plasma membrane primary cell wall

How is the cell wall of plant cells similar to an animal’s skeleton? How is it different? WORKTOGETHERWORKTOGETHER

Chloroplast thylakoid outer membrane inner membrane channel interconnecting thylakoids 1 micrometer stroma granum (stack of thylakoids)

Leucoplasts and other plastids starch globules 0.5 micrometer plastid

What do chloroplasts do? 1.Make energy 2.Use energy to make molecules. 3.Break sugar down to release energy.

Chloroplasts carry out photosynthesis to make sugars and other monomers. What does the plant use these monomers for? WORKTOGETHERWORKTOGETHER

One-celled Eukaryotic organisms have unique challenges. A Paramecium must: ingest food excrete waste sense and respond to the environment

(a) Cilium (b) Flagellum propulsion of fluid return strokepower stroke plasma membrane direction of locomotionpropulsion of fluid continuous propulsion

cilium Paramecium 0.1 micrometer protein "arms" central pair of microtubules section of cilium (transmission EM) basal body plasma membrane

contractile vacuole full reservoir contracted reservoir

pore collecting ducts central reservoir Reservoir contracts, expelling water through pore. Water enters collecting ducts, fills central reservoir.

In a one-celled organism, which organelle is most like: A stomach (assists with digestion)? A kidney (removes excess water)? WORKTOGETHERWORKTOGETHER

Recap Prokaryotic cells have no membrane- bound organelles. Eukaryotic cells have membrane-bound organelles, which compartmentalize processes for better efficiency. ALL cells have a cell membrane and DNA.