cell discovery, theory, & organelles direct instruction synthesize notes on 26r
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Cell Discovery, Theory, & Organelles
Direct InstructionSynthesize Notes on 26R
Cell Diversity and Size
First Sightings of Cells
Around 1590, the invention of the microscope made it possible for people to discover and learn about objects on the micro (µ) scale. Micro = 10-6
One of the first people to observe cells was Robert Hooke. He looked at cork samples and named what he saw “cells”.
Robert Hook’s composite microscope
Anton von Leeuwenhoek was the first person to observe what are now called bacteria.
Matthias Schleiden found that all plants are made of cells.
Theodor Schwann, found that all animals are made up of cells.
Rudolf Virchow proposed that new cells are formed only from existing cells
The Cell Theory
One of the fundamental ideas of modern biology
Includes 3 principles: 1. All living organisms are composed of
one or more cells 2. Cells are the basic unit of structure
and organization of all living organisms 3. Cells arise only from previously
existing cells
Remember 2 major cell types
EukaryotesProkaryotes
Prokaryotic cells Cells that do not
contain a nucleus & membrane bound organelles
Prokaryotes contain DNA, but only a single, circular molecule
Which kingdoms contain living organisms with only prokaryotic cells?
PROKARYOTES
• UNICELLULAR ORGANISMS
• EXAMPLE= cyanobacteria
Fossil 2 billion years old (left) and living (right). Note the similarities in
appearance. Interspersed among the cyanobacteria colonies are chains of rod-
shaped bacteria.
Eukaryotic cells Contain a nucleus
and membrane-bound organelles
More advanced – organelles allow specialized cell functions to take place in different parts of the cell at the same time
Which kingdoms contain eukaryotic cells?
INTERNAL ORGANIZATION
• ORGANELLES:– CELL COMPONENT THAT PERFORMS SPECIFIC
FUNCTIONS FOR THE CELL
Parts of the cell that both eukaryotes and prokaryotes have
Most cells have a: Cell Wall
Cell wall Thick, rigid, mesh of fibers that
surrounds the outside of the plasma membrane, protecting the cell and giving it support
Which Kingdom does NOT have a cell wall??
Make sure you know what each kingdom’s cell wall is composed of!!
All cells have a: Plasma membrane PLASMA MEMBRANE
Plasma membrane – flexible boundary that controls the movement of substances into and out of the cell
Plasma Membrane The plasma membrane has selective
permeability: Allows some substances to pass through while
keeping others out
Structure of the plasma membrane
The plasma membrane can have this selective permeability because it is composed of a phospholipid bilayer Phospholipid bilayer = two layers of phospholipid
molecules arranged with polar heads facing outside and nonpolar tails facing inside
Plasma membrane – phospholipid bilayer
Plasma membrane continued… Proteins are embedded
in the phospholipid bilayer Held in place by polar
(charged)/non-polar attractions
Help cells recognize each other
Recognize & bind specific substances
Move substances in and out of cell
The phospholipids create a “sea” in which other molecules can float, like apples floating in a barrel of water.
All Cells HaveCYTOPLASM:
– CELL GOO INSIDE CELL
– WHERE THE ORGANELLES ARE LOCATED
– ALSO CALLED CYTOSOL
Cytoplasm Cytoplasm=
semifluid material inside the cell’s plasma membrane
In prokaryotes, all of the cell’s functions take place directly in the cytoplasm
In eukaryotes, all of the cell’s functions take place within organelles in their cytoplasm Cytoplasm
Cytoskeleton Supporting network
of long, thin protein fibers that form a framework for the cell and provide an anchor for the organelles inside the cells
CYTOSKELETON• NETWORK OF LONG
PROTEIN STRANDS IN THE CYTOSOL
• NO MEMBRANE• AIDS IN MOVEMENT OF
ORGANELLES • MICROFILAMENTS:
– THREADS OF A PROTEIN CALLED ACTIN.
– SMALLEST STRAND MAKES UP CYTOSKELETON
MICROTUBLES:• LARGEST STRANDS • HOLLOW TUBES• WHEN CELL IS ABOUT TO DIVIDE BUNDLES COME TOGETHER AND EXTEND ACROSS THE CELL
SPINDLE FIBERS:
• THICK BUNDLES
• ASSISTIN MOVEMENT OF CHROMOSOME DURING CELL DIVISION
All cells have: RIBOSOMES• MAKES PROTEINS
• MOST NUMEROUS ORGANELLE IN THE CELL
• NO MEMBRANE
• 60% RNA AND 40% PROTEINS MAKE UP RIBOSOME'S
• PRODUCED & ASSEMBLED IN THE NUCLEOLUS
• Many Proteins are produced by a specialized cell, e.g. antibodies– transported and used
elsewhere in the organism• WHEN RIBOSOMES ARE
ATTACHED TO ER:– PROTEINS INSERTED TO
MEMBRANES
– PROTEINS EXPORTED FROM CELL
Electron Micrograph of ribosomes. The ribosomes operate in chains when translating a
mRNA.
Proteins (AA chains) being made by ribosomes from mRNA
Once amino acids bond together to form a chain, it is now a protein, and can be used by the body.
Simplified translation on the ribosome
JHK
JHK
JHK
PROTEIN CHAIN
JHK
JHK JHK
JHK
JHK
JHK
JHK JHK JHK
JHK
RIBOSOMES Allow PROTEIN CHAINS to be made correctly
Translation = the language of nucleic acids translated to the language of proteins
Eukaryotes have organelles that prokaryotes do not have.
NUCLEUS:– LARGE
– NEAR CENTER OF CELL
– CONTAINS MOST OF CELLS GENETIC INFO
– DIRECTS MOST ACTIVITIES OF CELL
Nucleus In eukaryotic cells, the
central membrane-bound organelle that manages cellular functions and contains DNA
Surrounded by a nuclear envelope – a double membrane that has nuclear pores to allow substances in and out of the nucleus
• NUCLEAR MATRIX= PROTEIN SKELETON
• NUCLEAR ENVELOPE= DOUBLE MEMBRANE AROUND NUCLEUS
• CHROMOSOME= DENSELY PACKED (“X”) CHROMATIN
• CHROMATIN= COMBO OF DNA & PROTEIN (stretched out chromosome)
• NUCLEAR PORE= SMALL HOLES (Doors)
• NUCLEOLUS= RIBOSOME SYNTHESIS, PRODUCTION
nuclear pores
nucleus
ENDOPLASMIC RETICULUM (ER)• A SYSTEM OF MEMBRANE BOUND SACS AND TUBULES• INTRACELLULAR “HIGHWAY”
– MOLECULES MOVE FROM ONE PART OF CELL TO ANOTHER• 2 TYPES OF ER:
– SMOOTH ER= (no ribosomes)
– ROUGH ER= (COVERED W/RIBOSOMES)
Endoplasmic reticulum Highly folded
membrane system in eukaryotic cells that is the site for protein and lipid synthesis
ROUGH ER:• MAKE PROTEINS
• USED FOR EXPORT OUT OF THE CELL
• ALSO TO BE INSERTED INTO THE CELL MEMBRANE
SMOOTH ER: • INVOLVED IN
PRODUCTION (SYNTHESIS) OF STEROID GLAND CELLS
• REGULATION OF CALCIUM LEVELS
• BREAKDOWN OF TOXIC SUBSTANCES BY LIVER CELLS
SMOOTH ER
ROUGH ER
Golgi apparatus “UPS crew” Flattened stacks or sacs of membranes that
modifies, sorts, and packages proteins into sacs called vesicles Vesicles can fuse with the cell’s plasma membrane
to release proteins to the environment outside of the cell
GOLGI APPARATUS• PROCESSING• PACKAGING• SECRETING
ORGANELLE• SYSTEM OF
MEMBRANES “PANCAKES”
• MODIFIES PROTEINS FOR EXPORT BY CELL
Vacuoles “storage crew” Membrane-bound
vesicle for temporary storage of materials such as food, enzymes, and wastes
LYSOSOME “clean up crew”
• SMALL• SPHERICAL ORGANELLE • ENCLOSE ENZYMES in a
SINGLE MEMBRANES• DIGEST PROTEIN, CARBS.,
LIPIDS, DNA, RNA– When needed: OLD
ORGANELLES, VIRUSES, BACTERIA THAT WERE INGESTED
• RARE IN PLANT CELLS
MITOCHONDRIA
• CONTAIN THEIR OWN DNA (circular)
• SURROUNDED BY A DOUBLE MEMBRANE
Mitochondria “Power-house” “Mighty Mouse”
Converts fuel (sugars) into the energy molecule ATP for the rest of the cell
• TRANSFER ENERGY FROM ORGANIC COMPOUNDS (pyruvate) TO ATP VIA CHEMICAL RXN’S
• ATP = (AdenosineTriPhosphate) MOLECULE THAT MOST CELLS USE AS ENERGY CURRENCY
• CAR (MITOCHONDRIA)
• GASOLINE (CHEMICAL RXN)
• GAS + ENGINE = CAR STARTS (ATP MADE)
• CAR RUNS (ENERGY)
MITOCHONDRIA IN HUMAN LIVER CELL
• SURROUNDED BY:
• 2 MEMBRANES– OUTER & INNER
• CRISTAE:– THE LONG FOLDS OF
THE INNER MEMBRANE
• ENLARGE SURFACE AREA
• WHERE CHEMICAL RXNS TAKE PLACE
HOW CELLS MOVE• CELLS USE HAIRLIKE STRUCTURES THAT
EXTEND FROM THE SURFACE OF THE CELL
• SHORT & IN LARGE QUANTITIES = CILIA
• LONG & LESS NUMEROUS = FLAGELLA
Cilia and Flagella Flagella
Long, tail-like projection with a whiplike motion that helps a cell move through a watery environment
Cilia Short, numerous
projections that look like hair and function in cell movement
Plant cells have 3 structures that animal cell lack
1. Cell wall 2. Chloroplasts 3. Central vacuole
Chloroplast Double membrane
organelle that captures light energy and converts it to chemical energy through photosynthesis
Central vacuole Membrane bound space that stores water;
Aids in the rigidity of the cell
Draw/Color Plant Cell
Draw/Color Animal Cell
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