4-1 Introduction to the Cell Biology – The study of life
Bio – life Ology – study of
Cell – smallest unit of matter that can carry on all life functions
Saw “little boxes” Reminded him of small
rooms that monks lived in called cells
So that is how cells got their name!
Cell Theory 150 years later …. Cell theory – 3 parts
1. All living things are composed of at least one cell
2. Cells are the basic unit of structure and function in an organism
3. Cells come from other cells
A. Size Most are microscopic few are seen by the
naked eye Size is limited by: Ratio of surface area to volume
Nutrients must enter the cell If it is too large – materials won’t enter the
cell fast enough
C. Internal Organization Organelles – cell component that performs
a specific function Like organs of the body – “Itty bitty baby
organs”
EUKARYOTIC CELL Eukaryotic cell – has a nuclear membrane
and membrane- bound organelles Just like you and me!! All cells that are not bacteria
I. Cell Membrane Holds everything inside the cell Semipermeable – (selectively permeable) –
Only allows some things through
Cell Mem. Make-up Made of:
Phospholipid bilayer – fat with a phosphate group attached
Proteins – allows certain things through
The phospholipid Hydrophilic end Hydrophobic end Latin:
Hydro=__________ Philic=__________ Phobic=__________
The cell membrane Proteins Some proteins
go all the way through the mem.
These serve as channels or pores
Fluid Mosaic Model of cell mem For many years scientists thought that
proteins were static (stuck in 1 place)
The phospholipid bilayer behaves more like a fluid than a solid Proteins can move Cell membrane is always changing
2. Mitochondria (MIGHTY) Powerhouse of the cell
(Makes energy) Makes ATP (adenosine
triphosphate) -molecule that gives us energy
Double membrane with series of folds (Cristae)
Highly active cells= lots of mitochondria
Has own DNA Comes from your mama
3. Ribosome Help make proteins Most numerous NOT membrane bound (in bth eukaryotic
and prokaryotic cells) Some are free others are attached to the
endoplasmic reticulum
4. Endoplasmic Reticulum System of tubules and sacs Function= path for molecules Two types:
1. Rough E.R. – has ribosomes
2. Smooth E.R.- no ribosomes
Smooth Endoplasmic Reticulum Forms channels
within the cell Breaks down and
make lipids Helps detoxify
chemicals
Rough Endoplasmic Reticulum Rough b/c of
ribosomes on the outside
Ribosomes help make proteins
RER connects to the nucleus and helps make proteins
5. Golgi Body (apparatus) Processing,
packaging, and shipping proteins
Stacked membranes Vesicles (membrane
bound bags) carry materials.
6. Lysosome Latin: Lys – to break or split Sac filled with digestive enzymes Digests anything bad – like the garbage
disposal of the cell. Suicide sac-can kill a cell
Human hand begins as a solid and lysosome kills cells to make spaces btwn fingers
7. Cytoskeleton Provides support Move organelles within the cytoplasm Two types:
1. Microfilaments – play a role in cellular movement
2. Microtubules – form spindle fibers (attach to centrioles and chromosome during cellular division
8. Cilia Short hair like extensions that help with
movement (made of microtubules) Single-celled organisms use it to move Multi-cellular organisms use it to clean
Ex: Respiratory system
Three main parts1. Surrounded by semi permeable membrane
(Nuclear membrane/ envelope) Double mem. That surrounds the nucleus Has pores
2. Nucleolus Helps make ribosomes
3. DNA
DNA (Deoxyribonucleic acid) Two forms of DNA
1. Chromosome )( - DNA is condensed around proteins – ONLY during cellular reproduction
2. Chromatin – DNA is all spread out like a plate of spaghetti