cells!. have we always known about cells? no, they are too small to see with just our eyes. first,...
TRANSCRIPT
Cells!
Have we always known about cells?
No, they are too small to see with just our eyes.
First, we needed the invention of the microscope to see things this small.
Compound microscope Specimen is magnified as light passes through several lenses.
Robert Hooke: English Scientist:
observed cork with a microscope. He thought the box-like structures he saw
looked like jail cells…
Anton Van Leewuenhooke:
Discovered bacteria, protizoa, and other microscopic organisms.
Electron Microscope
Some things are so small light waves totally miss them. Waves from electrons are used to “see” these very small objects.
Blood as seen with compound microscope
Blood seen with electron microscope
Pollen
Foot of house fly
Staple in Paper
Moth scales
Cell Theory:
Cells are the basic unit of life.
All cells come from pre-existing cells.
Exceptions to the cell theory
The First Cell could not have arisen from a pre-existing cell.
Viruses are not composed of cells but do contain genetic material.
Although considered organelles, Mitochondria and Chloroplasts contain genetic material and can reproduce inside a cell.
Two types of cells
Prokaryotic cells: Lack membrane bound structures such as a nucleus, mitochondria and chloroplasts.
Pro = before Karyotic = nucleus
Examples: Bacteria
Notice… no nucleus, no mitochondria, no chloroplasts
Eukaryotic cells
Have membrane bound structures such as a nucleus, mitochondria…
Eu = true Karyotic = nucleus
Examples: all other cells
Cell Size Prokaryotic/bacteria: very small… 1 to 10
micrometers Eukaryotic: bigger… from 10 to 100
micrometers Chicken egg cell = 6 cm (the whole egg) Nerve cell = 1 meter long Human egg cell = 100 micrometers Red blood cell = 9 micrometers Skin cell = 20 micrometers
White blood cell and bacteria
Cell size and surface area
Length of side (cm)
1 cm 3 cm
Total surface area (cm2)
Total volume (cm3)
Surface are to volume ratio
Cell size and surface area
Length of side (cm)
1 cm 3 cm
Total surface area (cm2)
1cm2 x 6 sides = 6cm2
9cm2 x 6 sides = 54 cm2
Total volume (cm3)
1x1x1 = 1cm3 3x3x3 = 27cm3
Surface are to volume ratio
6:1 54:27 = 2:1
Structural heirarchy: Atoms: elements = carbon, hydrogen Molecules: water, glucose Organelles: nucleus, ribosome Cells: muscle cell, blood cell Tissue: fat tissue, bone tissue Organ: Stomach, lung Organ system: digestive system Organism: us
Cell Organelles 1. Plasma membrane (cell membrane)
– Function: selectively permiable, keeps contents of cell in
– Structure: phospholipid bilayer
– In both plant and animal cells
Cytoplasm Function: site of many chemical
reactions, gives cell its shape
Structure: gel like substance made of 80% water.
Nucleus Function: the control center for all cell
functions. It controls growth and cell division
Structure: Envelope surrounding DNA
Nucleolus Function: Makes ribosomes
Structure: Dense body inside the nucleus
Endoplasmic Reticulum Function: Aids in the assembly and transport
of proteins and lipids.
Structure: a network of folded membranes that form channels from the cell membrane through the cytoplasm to the nuclear membrane
Ribosome: Function: assembles proteins
Structure: small dot like structures found on the E.R. or in cytoplasm
Mitochondria Function: break down carbohydrates
and sugars, making energy from the food we eat
Structure: 2 membranes, inner membrane folded, has own DNA
Golgi Complex Function: Packages materials for
release from the cell. Structure: Stacks of flattened
membranes and vesicles budding off
Lysosome Function: disposal and recycling units of the
cell. (little stomachs)
Structure: Membrane bound structures containing enzymes necessary for digesting certain material in a cell
Vacuole: Function: stores food, water, and waste
Structure: fluid filled sac (plant cells have large vacuoles)
Centriole: Function: aids in animal cell division
Structure: nine sets of three fused microtubles arranged in an open star shape and located just outside of the nucleus
Chloroplast Function: turns the sun’s energy into
food (photosynthesis) Structure: 2 membranes, oval, green
Cell Wall Function: support and structure for cell.
Structure: cellulose fibers
Cell Membrane
Phospholipid bilayer
Selective Permeability
The following substances can easily pass through the cell membrane….
Lipid soluble substances
Small stuff – Glucose, oxygen, carbon dioxide, ions
Passive Transport: no energy required
Diffusion: movement of molecules from a high concentration to a low concentration
Facilitated diffusion– Membrane proteins help molecules pass
through the cell membrane.
Osmosis: Movement of WATER molecules from a high to a low concentration.
Active Transport: requires energy (ATP)
Movement of molecules from a Low to a High concentration.
Facilitated transport:– Some membrane proteins require energy
to move molecules through the cell membrane.
Pinocytosis: cell drinking
Phagocytosis: cell eating
Cell Organelle Lab These pictures are what you should
have seen in the microscope…
Cork
Elodea
Cheek cells
Onion skin