“We, all of us, are what happens when a primordial mixture of hydrogen and helium evolves for so long that it begin to ask where it came from” -Jill Tarter Life’s home: The Cell Chapter 4

Cell Theory All living organisms are composed of cells Unicellular or multicellular Cells come from _______ cells Modern additions to the theory All cells use energy and have a metabolism All cells have similar chemical composition All cells have genetic information in the form of DNA

Cells are Specialized Over ____ different cells in the human body You are made of trillions of cells!! Reproductive cells Red blood cell Cardiac muscle cells Bone cells Nerve cell

Why so small? Surface area to volume ratio! Greater surface area means greater ________ Transporting stuff into and out of the cell

Two Main Groups of Cells Prokaryotic (Bacteria and Archaea) Eukaryotic (Protists, Plants, Animals and Fungi) *Not to scale

Prokaryotic and Eukaryotic Cells Prokaryotic cell

Size of Prokaryotic Cells

Domains of Life Bacteria Archaea Eukarya Unicellular prokaryotes Extremophiles Eukarya Unicellular and __________ eukaryotes Protists Fungi Plants Animals

Domain: Bacteria Prokaryotic cells No membrane bound nucleus or organelles Single-celled organisms Asexual reproduction ___________ in cell wall separates bacteria from archaea

Domain: Archaea Prokaryotic cell but similar to Eukaryotes in DNA replication and Protein synthesis More closely related to ___________ ______________: organisms that live grow best in one or more conditions that would kill most organisms Thermophiles: live in extremely hot environments Halophiles: live in extremely salty environments Methanogens: Methane releasing archaea that are poisoned by oxygen

A Borrowed Life Virus: an infections particle incapable of replicating outside of a cell, which consists of an RNA or DNA genome enclosed in a protein coat (capsid) ________________ parasites Arguments for describing viruses as non-living Can not __________ outside of host cell Can not carry out ________________ outside of host cell Lack ribosomes and enzymes HIV attacking a white blood cell

Prokaryotic Cells Pili: attachment structures on the surface of some prokaryotes ________: location of cell’s DNA (not enclosed in a membrane) Ribosomes: site of protein synthesis Cell wall: rigid structure outside of cell membrane Bacterial chromosome ____________: sticky outer coating on many prokaryotes A typical rod-shaped bacterium Flagella: locomotion organelles in some bacteria A thin section through the bacterium Bacillus coagulans

Eukaryotic Cells

Prokaryotic Reproduction ____________: DNA replicates and then the cell divides into two separate cells

Prokaryotic and Eukaryotic Cells Characteristics Prokaryotic Cells Eukaryotic Cells Cell Size Small (0.2 – 2.0 µm in diameter) Large (10 – 100 µm in diameter) Organization Always single celled Often _________________ Nucleus _________________ or nucleus, Nucleoid Membrane bound nucleus Membrane-enclosed organelles ___________ Present (e.g. lysosomes, Golgi complex, mitochondria) Cytoplasm No cytoskeleton or cytoplasmic streaming Cytoskeleton, cytoplasmic streaming Ribosomes Present, smaller size Present, larger size Chromosomes (DNA) Usually _______________ chromosome _______________ chromosomes Cell division Binary fission Involves mitosis Sexual Recombination None, transfer of DNA only Involves meiosis

Major Components of Eukaryotic Cells Nucleus: membrane bound region that contains the cell’s DNA Organelles: highly organized structure in the cell that performs a specific cellular function Cytosol: protein rich, jelly-like fluid in which the organelles are immersed Cytoskeleton: internal supports of the cell made up of protein fibers Plasma membrane: a complex, ___________ membrane that encloses the cytoplasm and regulate passage of ions and molecules into and out of the cell Nucleus Other organelles Cytosol Cytoskeleton Plasma membrane

Origin of Organelles Autogenesis: _______ of prokaryote plasma membranes lead to compartmentalization Endoplasmic reticulum, golgi, nuclear membrane _________________: one organism lives inside the cell of another organism Mitochondria, chloroplasts Endosymbiosis Autogenesis Endosymbiosis

Specific Functions of Organelles

The Nucleus Control center of the cell Stores DNA Nuclear membrane Chromatin: uncoiled DNA ______________: coiled DNA containing genes Nuclear membrane Contains pores Nucleolus: region inside nucleus where ribosomal subunits in manufactured Chromosome DNA Nucleus Nucleolus Gene

Endomembrane System Rough endoplasmic reticulum: network of membranes that aid in protein processing Studded with ___________ Smooth endoplasmic reticulum: network of membranes that functions in the synthesis lipids and ___________ of harmful molecules including alcohol, drugs and metabolic wastes. Lacks ribosomes

Golgi Complex Protein processing and distribution _____________ determine shipping route

Lysosomes _______ old cellular products and foreign material Cell “digestive system” Recycles useable molecules Go on to form new organelles Found in _______ cells

Protein Production Summary

Protein Production: Step 1 ______________: process in which a section of DNA is copied onto messenger RNA (mRNA) RNA polymerase mRNA DNA Direction of transcription

Protein Production: Step 2 Translation: process by which a __________ is produced in a ribosome from information encoded within a messenger RNA

Mitochondria Creates Adenosine Triphosphate (ATP) from food (cellular respiration) ATP = cellular energy Requires macromolecules from food and O2, expels CO2 Breakdown generates _____ (metabolic heat)

Cell Cytoskeleton Aids in cell structure, cell movement and transport of materials within cell Made up of three types of protein fibers Microfilaments: solid, rod-like fibers that aid in cell division and changes in cell shape Intermediate filaments: rope-like structures that give the cell strength and maintain cell shape ___________: long hollow tubes that aid in the movement of molecules and organelles throughout the cell

Cell Movement Modified microtubules ____: short, hair-like projections often found in large numbers on the exterior of the cell. Used for locomotion or movement of fluid around a cell. Flagella: long, tail-like extension used for locomotion. Typically one per cell

Plant and Animal Cells

Plant and Animal Cells Animal Cell Plant Cell Both

Plant Cells: Chloroplasts Contain chlorophyll (photosynthesis) Endosymbiosis Thylakoid

Plant Cells: Central Vacuole Maintains cell pressure Stores __________ Degrades cell waste products Large central vacuole

Plant Cells: Cell Wall _________: polysaccharide that is a main structural component of cell walls Limits water absorption Structural strength

Cell Communication Plant Cells Plasmodesmata: channels between plant cell walls Creates continuous cytoplasm Do not open and close

Cell Communication Animal Cells Gap junctions: protein assemblage that forms a communication channel between adjacent animal cells Open and close as needed