Name __________________________________ Test Date__Tue, Oct. 4 th ______ UNIT III - CELL STRUCTURE AND FUNCTION I. DISCOVERY OF CELLS A. History of Microscopes The invention and development of the microscope in the 1600’s enabled scientists to discover and study cells - basic unit of structure and function in in all living things 1. Anton von Leeuwenhoek – was the first to try stacking several lenses _ together to view tiny objects. He looked at pond water _ through his lenses and became known as the first scientist to describe living cells as seen through a microscope. 2. Robert Hooke - In 1665, he used a _ microscope _ to examine thin slices of cork and then described what he saw and called them _ cells __. He chose the name “cells” because the chambers he saw reminded him of the rooms in a monastery which were called cells.
Transcript
Name __________________________________ Test Date__Tue, Oct. 4 th ______
UNIT III - CELL STRUCTURE AND FUNCTION
I. DISCOVERY OF CELLS A. History of Microscopes The invention and development of the microscope in the 1600’s enabled scientists to discover and study cells - basic unit of structure and function in in all living things
1. Anton von Leeuwenhoek – was the first to try stacking several lenses_ together to view tiny objects. He looked at pond water_ through his lenses and became known as the first scientist to describe living cells as seen through a microscope.
2. Robert Hooke - In 1665, he used a _microscope_ to examine thin slices of cork and then described what he saw and called them _cells__. He chose the name “cells” because the chambers he saw reminded him of the rooms in a monastery which were called cells.
B. Cell Theory Nearly a century after Hooke’s findings, several other scientists discoveries led to the formation of the _cell theory_.
1. Matthias Schleiden (botanist) & Theodor Schwann (zoologist) –together they reached the conclusion that ____all ____ living things were composed of cells _.
2. Rudolf Virchow – elaborated on Schleiden & Schwann’s proposal and added “omnia cellula e cellula” : all cells come from cells _
These discoveries, confirmed by other biologists, are summarized in the cell theory, a fundamental concept in Biology….. The cell theory states that:
a. All organisms are ____composed of cells______ b. Cells are the smallest working units of life. c. All cells come from ____pre-existing cells________
II. TYPES OF CELLS Living organisms are made of either _prokaryotic__ or _eukaryotic_cells – the two major kinds of cells which can be distinguished by _structural organization__
PROKARYOTIC EUKARYOTIC_Bacteria_____; Divided into two kingdoms, _Archaebacteria____ and _Eubacteria________
All organisms other than _bacteria______; Found in kingdoms _Protista____, _Fungi__, _Plantae___, and _Animalia______
_No_ true nucleus; Lack nuclear envelope
_True____ nucleus surrounded membrane known as nuclear envelope
Genetic material present in_nucleoid___________ region
Genetic material contained within_nucleus______________
A. Prokaryotic Cells – All Unicellular 1. Eubacteria – “True” Bacteria; Ex. include E.coli,Streptococcus.
2. Archaebacteria – “Ancient” bacteria; live in extreme environments (salty, hot, acidic); Ex. methanogens B. Eukaryotic Cells – Found in Unicellular and Multicellular organisms 1. Protista – ex. Amoeba, Euglena, Paramecium 2. Fungi - ex. Penicillium, yeasts, molds, mushrooms. 3. Plants – ex. Mosses, ferns, flowering plants. 4. Animals – ex. Sponges, worms, snails, insects, mammals.
III.
C. Microscopes - There are several types of modern microscopes: 1. Compound light microscope – More than one _lens (ocular & objective)________ uses light bent through lenses to magnify objects. 2. Electron Microscope – Uses _beams of electrons_________ . This enhances the resolution and magnification to allow researchers to study _cell structures____. There are two types of electron microscopes:
a. Transmission Electron Microscope or _TEM______________- electrons areTransmitted _through_____the specimen; used to study _internal___ cell structures.
b. Scanning Electron Microscope or _SEM_____ - uses electrons to trace the_surface_____ of the specimen; provides _depth___ of field or 3-D view.
III. CELL BOUNDARIES A. Cell Wall Cell Walls are the outer most boundary in _bacteria_, _plants_, and _fungi_. They are not found in __animal cells_____. The primary function of the cell wall is to _provide support and structure__.
Plants have cell walls made of _cellulose___ Fungi have cell walls made of _chitin____. Eubacteria have cell walls made of _peptidoglycan_____. The cell walls of _Archaebacteria___ are composed of other
_polysaccharides_____.
B. Cell Membrane Every cell is surrounded by the cell membrane. Its function is to maintain homeostasis__ in the cell by separating and protecting the cell from its environment. It also regulates exchange with the environment. The cell membrane is also called the __plasma membrane_. It is _selectively permeable_ which means that it allows some substances to pass through; acts a barrier to others.
IV. INSIDE A EUKARYOTIC CELL Within the cell membrane, the cell is composed of the nucleus with its corresponding structures, the _nucleolus_ and _nuclear envelope__.
The cytoplasm includes all the rest of the material inside the cell membrane. The cytoplasm includes two components: Cytosol – a semi-gelatinous substance that contains dissolved nutrients and wastes Organelles – means “little organs”. Each has a specific role in the overall function of the cell.
Illustration Structure Type of Cell Characteristics & Function
Nucleus Euk _Control center____ of the cell. Contains most of cell’s DNA; stored as _chromatin___ (_DNA_______ wrapped in _protein_____)
Nucleolus EukSmall, dense region in the nucleus. Involved in the synthesis of _ribosomes_____ which are required for _protein______ synthesis.
Nuclear Envelope Euk
Double membrane, each consisting of a _phospholipid bilayer__. Perforated by nuclear _pores______ which allow _RNA______ to leave the nucleus
Ribosomes Pro + EukTiny, non-membrane bound organelles located on _endoplasmic reticulum_____ (bound) or suspended in _cytosol_______ (free). Free ribosomes help manufacture _proteins_____ that will stay in the cell; bound ribosomes help make proteins that will be transported out of cell
Rough Endoplasmic
Reticulum
Euk
Extensive network continuous with _nuclear envelope______. Called “rough” due to presence of _ribosomes____ all along the membrane. Function of the rough ER is to _modify____ and transport _proteins_____. Most of these proteins are packaged into _vesicles_____ (bubbles or sacs made from membrane) and shuttled to the _Golgi apparatus________
Smooth Endoplasmic
Reticulum
Euk Similar to rough ER in structure, except that it lacks _ribosomes______. Smooth ER functions in the synthesis of _lipids_____, metabolizes _glycogen___, detoxifies _poisons_____ and _toxins___. Also stores _calcium__needed for muscle contractions.
Golgi apparatus
Euk Flattened, round sacs that look like a stack of _pancakes______. Receives, modifies, and ships products by way of _vesicles_______ into the
Found in _animal ___ cells only?? Membrane-bound sacs containing _hydrolytic enzymes___ that break down _biomolecules_______ and _recycle____ used cell components. Also used as defense against _bacteria________ and _viruses______
Vacuole Euk Sacs that may be used as _storage_____ for water, ions, wastes. Plants have a large central vacuole.
Mitochondria EukDouble-membrane organelle with inner folds called _cristae_____. Uses _glucose_______ to manufacture energy in the form of _ATP_____. Mitochondria have their own _DNA____.
Chloroplast Euk – Plant Cells
Found in _plant____ cells. Contain green pigment called _chlorophyll_________ and their own _DNA__________. Chloroplasts harvest energy from the _sun____ to produce _glucose____ through _photosynthesis______.
Centrioles Euk – Animal Cells
Found only in _animal__ cells. Bundles of _microtubules________ that play a role in _cell division_____.
Cytoskeleton EukNetwork of _protein____ fibers known as _microtubules______ and _microfilaments_________. Anchor _organelles______ and provide _support______. Also provide motility for some cells in the form of _cilia______ or _flagella________. More extensive cytoskeleton found in _animal____ cells.
