Biology I Chapters 23 & 24 Bacteria and Viruses

Do Now In two lines, explain the difference between prokaryotes and eukaryotes. Prokaryotic Does not have a nucleus or membrane-bound organelles. Eukaryotic Has a nucleus and membrane-bound organelles.

Do Now What are the two metabolic pathways by which cells obtain energy from nutrients? Aerobic Respiration Fermentation

Review What are the two kingdoms that prokaryotes compose? Archaeabacteria Eubacteria

Prokaryotes Prokaryotes-single-celled organisms that do not have a membrane-bound nucleus. Prokaryotes are the most numerous organisms on Earth. 3.5 billion years

Classification Eubacteria=Bacteria Archaebacteria=Archaea The phylogenetic relationship is based on comparisons of ribosomal RNA sequences. Bacteria can be classified according to their: Type of cell walls Methods of obtaining energy Gram-staining characteristics

Classification rRNA analysis shows that Archaea are more closely related to eukaryotes than they are to bacteria.

Do Now What is used to distinguish Archaea from Bacteria?

Archaea Archaea differs from bacteria in the makeup of their cell walls. Peptidoglycan-a protein-carbohydrate compound found in bacterial cell walls

Archaea Methanogens-convert hydrogen gas and carbon dioxide into methane gas Halophiles-“salt-loving”-live in environments that have very high salt concentrations Thermoacidophiles-live in very acidic environments that have very high temperatures

Bacteria Most known prokaryotes are bacteria. They occur in many shapes and sizes and have distinct biochemical and genetic characteristics.

Bacilli-rod-shaped Cocci-sphere-shaped Sprilla-spiral-shaped Bacteria Bacilli-rod-shaped Cocci-sphere-shaped Sprilla-spiral-shaped

Strept-chains Staph-grapelike cluster Bacteria Strept-chains Staph-grapelike cluster

Bacteria The procedure used to distinguish between two types of bacterial cell wall composition is called gram-staining.

Bacteria Gram-negative bacteria-have cell walls that are complex and have relatively small amounts of peptidoglycan. Stain red

Bacteria Gram-positive bacteria-simpler cell walls that have more peptidoglycan Stain purple

Cyanobacteria-use photosynthesis to get energy from sunlight

Structure and Function Cell Wall-gives shape and protects the cell from toxic substances Cell membrane-acts as a selective barrier Cytoplasm-a semifluid solution that contains ribosomes, DNA, small organic and inorganic molecules, and ions.

Structure and Function Capsule-an outer covering that protects the cell against drying out Pilli-short, hairlike protein structures on the surface of bacteria that help to attach the bacteria to surfaces Endospores-a thick-coated, resistant structure used by the bacteria when the environment gets harsh

Flagella-long, whip-like tail Movement Flagella-long, whip-like tail

Nutrition Photoheterotroph-Uses light energy but gets its carbon from other organisms Chemoheterotroph-obtains both energy and carbon from other organisms Photoautotroph-uses light energy and gets carbon from CO2 Chemoautotroph-obtain their energy from inorganic molecules, rather than from the sun

Do Now What form of asexual reproduction do bacteria do when the cell membrane pinches in two to form two identical daughter cells?

Reproduction Binary fission-a form of asexual reproduction when the cell membrane pinches in two to form two identical daughter cells.

DNA Exchange Transformation-occurs when a prokaryote takes in DNA from its outside environment.

Conjugation-the process by which two prokaryotes bind together and one cell transfers DNA to the other cell.

Transduction-a virus obtains a small part of DNA from a host prokaryote.

Pathology Pathology-the scientific study of disease Pathogen-bacteria and other organisms that cause disease Exotoxin-toxic substances that bacteria secrete into their environment. Endotoxin-toxic substances that are not released until the cell dies

Antibiotics Antibiotic-affect bacteria by interfering with certain cellular activities Prevent bacteria from making cell walls Broad-spectrum antibiotic-antibiotics that can kill more than one kind of organism Antibiotic resistance-the evolution of populations of pathogenic bacteria that antibiotics are unable to kill.

Foodborne Illnesses Many foodborne illness can be avoided by selecting, storing, cooking, and handling food properly.

Bacteria in Industry Buttermilk, Sour cream, Yogurt, Cheese Sauerkraut, Pickles, Coffee, Soy sauce, Acetone, Antibiotics, and Insulin.

Bioremediation-uses bacteria to break down pollutants Crash Course Liquid wastes Outflow

Do Now In the 1970s, many biotechnologists worked to develop a biodiesel that was an alternative to petroleum diesel. The results of their research was a biodiesel fuel that can be burned by most regular diesel engines and releases up to 50% less carbon emissions than petroleum diesel. If the majority of diesel-burning vehicles in the United States begin using biodiesel, what would be the most likely environmental impact? A. The amount of acid rain falling on the country will increase. B. Air quality across the country will improve. C. There will be no environmental impact. D. The amount of polluted runoff flowing into the ocean will decrease. Answer B

Do Now List four characteristics of living things.

Characteristics of Living Organisms Cellular organization Reproduction Metabolism Homeostasis Heredity Responsiveness Growth & development

Virus Virus-a nonliving particle made up of nucleic acid and a protein coat or nucleic acid and a lipid-protein coat Viruses are not living organisms, they are of interest to biologists because they cause many diseases in living organisms and they are useful tools for genetic research, and because they are active in living cells.

Viruses Why viruses are considered non-living: Cannot reproduce by themselves Are not made up of cells Cannot carry out metabolism by themselves

Characteristics of Viruses Viruses do not have cytoplasm or organelles Cannot carry out cellular functions Have genetic material Reproduce only in living cells.

Classification Viruses are classified according to whether they contain RNA or DNA, the shape of their genome, and whether they have a membrane envelope.

Structure A typical virus consists of a protein coat and a nucleic acid core. Capsid-a protein coat-surrounds some viruses; Protective outer coat

Lytic Cycle Lytic Cycle-a virus invades a host cell, produces new viruses, and ruptures the host cell when releasing newly formed viruses. Destroys host cell Bacteriophage (Phage)- a virus that infects a bacteria

Lysogenic Cycle Lysogenic Cycle-Viral DNA become integrated into the host cell’s DNA Temperate Virus-a virus whose replication includes the lysogenic cycle

Overview

Origin Most scientists think that early viruses originated from existing cell parts.

Viral Diseases Types of Viral Diseases Hepatitis SARS Shingles The clearing of forests for housing is associated with the emergence of viruses not previously seen in humans

Can be spread by: Mosquitoes Ticks Humans Viral Spread Can be spread by: Mosquitoes Ticks Humans

Vaccine Antibiotics are ineffective against viral infections because antibiotics interfere with cellular processes that viruses do not perform. Vaccination and vector control have been the most successful at fighting viral diseases.