Cells. Levels of cellular organization Atom Molecule Organelle Cell Tissue Organ Organ System...
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Transcript of Cells. Levels of cellular organization Atom Molecule Organelle Cell Tissue Organ Organ System...
Cells
Levels of cellular organization
Atom MoleculeOrganelleCellTissueOrganOrgan SystemOrganism
Cells
Prokaryotic
Bacteria
Eukaryotic
Animal Plant
Division of Cells
Eukaryotic Cells Literally means “True nucleus”
Have a nucleus Complex Cells Have membrane-bound organelles Organisms made of eukaryotic cells are called
“eukaryotes”Examples: Animals, Plants, Fungi, Unicellular organisms like paramecium and amoeba
Cellular Components
Cytoplasm Gel-like substance within the cell
where organelles are foundCytoskeleton
“Cell skeleton” Network of protein fibers that
maintain the shape of cell Composed of three networks of fibers
1. Microtubules: largest; hollow tubes made of protein; determine cell shape; scaffolding
2. Intermediate Filaments: Provide strength of cell
3. Actin Filaments: smallest; contractile string-like proteins that allow for cell movement
Cellular Components
Cell Membrane Semi-permeable barrier that
encloses the cell Regulates what enters and exits
the cell Provides protection Found in all types of cells
Cell Wall Porous, rigid barrier found
surrounding the cell membrane Adds additional layer of support
and protection Not found in animal cells
Organelles
Nucleus Houses the genetic
material (DNA) needed for replication of the cell
“Control Center” of the cell Contains the instructions
for the creation of proteins (made from DNA)Exterior: Surrounded by nuclear envelope: double-layered
membrane that encloses the DNA; contains nuclear pores: small openings that allow for the passage of molecules between the cytoplasm and the nucleus
Interior: DNA in the form of chromatin (string-like)• Nucleolus: where ribosomes are made; very dense region
Organelles
Endoplasmic Reticulum A grouping of sac-like
structures Two Types of ER:
Rough ER: contain ribosomes (creating ‘rough’ appearance); involved in the process of protein synthesis
Smooth ER: no ribosomes; involved in lipid synthesis
Ribosomes Location where proteins are
made (protein synthesis)
Organelles
Golgi Apparatus Looks like a stack of membranes (pancake-like
appearance) Modifies, sorts and packages proteins received from
the ER. Break off from the golgi apparatus; floats freely in the
cell or travels to cell membrane where it will eventually exit the cell.
Creation of lysosomes
Organelles
Lysosomes Contain enzymes necessary for digestion of cell food
or waste Can break down lipids, carbs, proteins Digest non-functional organelles, ‘cleaning up’ the cell
Organelles
Vacuoles Sac-like structure responsible for storage of various
materials (e.g. water, carbs, proteins, etc.)
Organelles
Mitochondria The “Powerhouse” of the cell Convert food energy into energy that is used by the
cell itself (for growth, development, movement, etc.) via cellular respiration ATP (Adenosine Triphosphate)
Complex structure
Organelles
Chloroplast Site of photosynthesis
Energy from sun is captured and converted into chemical energy
Contain the pigment chlorophyll which absorbs solar energy used in photosynthesis Responsible for the green
color of plants
Organelles
Centrioles Made of microtubules Located near nucleus Organize microtubules within the cytoskeleton prior
to cell division
Division of Cells
Prokaryotic Cells Include Bacteria & Archaea Literally means “before nucleus”
So-have no nucleus Lack membrane-bound organelles Simpler and much smaller than Eukaryotes Organisms made of prokaryotic cells are called
“prokaryotes”
Structure of Prokaryotes
Three basic shapes1. Bacilli: rod-shaped bacteria2. Cocci: Spherical-shaped bacteria3. Spirilla: Spiral-shaped bacteria; flexible
Prokaryotic Cell Parts: Interior
Do prokaryotic cells have DNA if they lack a nucleus?
Nucleoid: a region within the cytoplasm of the cell in which the DNA is located; center of the cell (no membrane encloses the DNA)
Cytoplasm Semifluid, gel-like solution
encased within the cell membrane of the cell
Interior
Ribosomes Made of two subunits
(each containing a combination of various proteins and rRNA) which work together to synthesize protein
Located throughout the cytoplasm
External Layers
Cell Membrane Regulates the entrance
and exit of various substances in and out of the cytoplasm
Cell Wall Provides shape,
structure, and support for cell
Glycocalyx The outermost layer of
bacterial cells; gel-like protective layer
External Structures
Flagella Allows for cell movement Long, rotating filament that
propels the cell forwardFimbriae
Hair-like bristles located on the external surface of the cell
Allow cells to attach to surfaces
Conjugation Pili Tube-like structures that
allow for bacteria to pass DNA from cell to cell; usually larger and less numerous than fimbriae