Cells and Tissues (Part I): • Cytology: the study of cells • Histology: the study of tissues • Levels of Organization: cell---tissue---organ--- system • Cell as basic unit of life Bathed in interstitial fluid (salt H 2 O) • Structure related to function • Variety of cell types (sizes, shapes, functions) • Unicellular Organism: consists of one cell (bacteria) • Multicellular Organism: consists of more than one cell
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Cells and Tissues (Part I): Cytology: the study of cells Histology: the study of tissues Levels of Organization: cell---tissue---organ---system Cell as.
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Cells and Tissues (Part I):
• Cytology: the study of cells• Histology: the study of tissues
• Levels of Organization: cell---tissue---organ---system• Cell as basic unit of life Bathed in interstitial fluid (salt H2O)
• Structure related to function• Variety of cell types (sizes, shapes, functions)
• Unicellular Organism: consists of one cell (bacteria)• Multicellular Organism: consists of more than one cell
• Prokaryotic Cell (Prokaryote): primitive Nuclear material spread out No nuclear membrane Examples: Bacteria and blue-green algae
• Eukaryotic Cell (Eukaryote): advanced Nuclear material confined within a nuclear membrane Examples: All cells except bacteria and blue-green algae
• Characteristics of Cells: Nutrition: involves the cell’s need for taking in food Digestion: the breakdown of food Reproduction: to make a copy Cellular Respiration: food being changed into energy Excretion: getting rid of wastes
Secretion: to release a product Synthesis: to make a product Irritability: response
• Cell Theory:• Schleiden (1804-1881); Schwann (1810-1882) All living things are composed of cells. All cells are similar in structure and function. The structure and function of an organism involves the organization
and action of all its cells. All cells come from pre-existing cells (Virchow)
• Exceptions: Viruses Cell parts that reproduce (mitochondria, chloroplasts) Not all cells are separated by a cell membrane (muscle)
Cell Biology Discoveries:
• Robert Hooke (1665): coined the term “cell ” (cork)• DuJardin: discovered cytoplasm• Robert Brown: discovered the nucleus
Cell Organelles (Cell Parts):
• Protoplasm: a clear jelly-like material (colloid) Contains H2O, wastes, nutrients
Cytoplasm: protoplasm within the cell membrane Keeps the cell hydrated
Nucleus
• “Control Center” Controls everything in the cell Contains DNA
• Has a double-layered membrane with pores
• Shape of nucleus conforms to the shape of the cell
• Involved with energy/ metabolism/cellular respiration/form ATP
• Contains cristae hold enzymes increase surface area
Ribosomes
• Made by the nucleolus
• Involved in protein synthesis
• Attached: on ER (protein sent out of the cell)
• Floating: in the cell (protein within the cell)
• Made up of RNA
Endoplasmic Reticulum
• Channel inside the cell
• Rough ER: contains ribosomes (protein sent out of the cell)
• Smooth ER: does not contain ribosomes (fats sent out of the cell)
Golgi Bodies
• “Packaging Center”
• Stack of coins
• Secretion
Secretion
Vacuoles
• Clear bubbles
• Hold Water
• Prevent dehydration
• Animal (small, several)
• Plant (few, large)
Lysosomes
• “Suicide Sacks” (membrane made fragile by high amounts of vitamin A)
• Contain digestive enzymes
Act as scavengers Eat old cell parts
• Related to aging, arthritis?
Peroxisomes
• “Detox Units” Filters all poisons Change free radicals to H2O2
Enzyme catalase converts H2O2 to H2O
• High number in kidneys and liver
• Tiny bubbles
Microtubules/Microfilaments
• “Skeleton of the Cell”
• Microtubules (support or shape); mini tubes
• Microfilaments (cell movement); threads
• Intermediate filaments:
Help to form
desmosomes
Plant Cell
• Cell Wall (to prevent dehydration)
• Chloroplasts (contain chlorophyll)
Green organelles Involved in photosynthesis
• Large Vacuoles
Cell Membrane:
• Surrounds both animal and plant cell to prevent dehydration• Semi-Permeable Membrane: Contains pores Some particles move inside the cell; Some particles move out of
the cell; Cell membrane is selective Movement depends on: size of particles, chemistry of particles,
temperature, pressure
• Sandwich Model (1935): Static model 2 phospholipid layers (phosphate + fat) between 2 layers of protein
• Fluid Mosaic Model (1970): Dynamic model Proteins immersed in the 2 layers of phospholipids (fluid)
Specializations of the Cell membrane:
• Gap Junctions: allow communication between cells (heart, embryonic cells)
• Microvilli: fingerlike projections that increase absorption• Desmosomes: buttonlike thickenings which aid in protection from
• Mutation: a mistake in nitrogen base pairs• Pattern of bases codes for a specific amino acid• Codon: 3 letter (bases) code for 1 amino acid
• Replication of DNA (Making an identical copy)
DNA unzips and hydrogen bases separate (action of DNA polymerase)
Free-floating nucleotides match up on each side Hydrogen bonds reform Result: 2 identical DNA molecules (Each contain 1 of
the original DNA strands) Semi-Conservative Model of Replication
• Each DNA molecule with a new strand and an old strand
• DNA never leaves the nucleus
Ribonucleic Acid (RNA)
• Made up of nucleotides• Sugar called ribose• Nitrogen Bases: A, C,G,U• Single-stranded• Located in the nucleus and in the ribosomes• 3 Types: Messenger RNA (mRNA); carries message of DNA to ribosomes (3
letter code – codon); single strand of letters Transfer RNA (tRNA): reads the mRNA code at the ribosomes (3
letter code – anticodon); carries an amino acid; shamrock shape Ribosomal RNA (rRNA): joins mRNA to tRNA
Transcription
• Making of mRNA from one side of DNA in nucleus
DNA polymerase unzips DNA Hydrogen bonds break and
energy is released One side of DNA acts as a
“template” (model) for making mRNA
Free-floating nucleotides line up and form mRNA
DNA reforms mRNA carries the message of
DNA to ribosomes
Translation
• Occurs at the ribosomes• Anticodon of tRNA joins
with codon of mRNA (rRNA helps)
• Amino acid pops off end of tRNA
• Amino acids string together to form a protein (Protein Synthesis)