Cells: Structure and Function


Today in class, we took notes on cells and their functions in the green packet.
What are the structures? What do they do?

All cells come in different shapes and sizes, and it is impossible to see a plant or animal cell with the naked eye.

1. Light Microscope – visible light passes through the specimen, glass lenses enlarge the image. (the microscopes we use in class)

· Resolving power = 0.2 micrometers (one thousand micrometers in a millimeter)

2. Electron Microscope – uses beam of electrons instead of light

· Resolving power = 0.2 nanometers ( hundred thousand in a millimeter)

A. Scanning electron microscopes look at the actual surface of a cell

B. Transmission electron microscopes explore the inside of a cell

I. Prokaryotic vs. Eukaryotic

Prokaryotic: Eukaryotic:

Prokaryotic cells contain bacteria and archaea. Eukaryotic cells contain protists, plants, animals, and fungi.

Pro = before Eu = true

Karyon = kernel (nucleus) Karyon = kernel (nucleus)

II. Plant Cells and Animal Cells

Plant Cells Contain:
· Plasma membrane
· Nucleus
· Cytoplasm/Cytosol
-Chloroplasts/plastids (not green)
· Cell walls (forms a rigid, rectangular shape, not flexible)
· Square morphology

Animal Cells Contain:
· Plasma membrane
· Nucleus
· Cytoplasm/Cytosol
· Centriole (cell division)
· Round morphology (a more circular shape, flexible)

III. Cell Organelles

Organelle – (little organs) structure with a specialized function within a cell.

Organelles are eukaryotic.

Organelles are made up of a cell membrane that contains a nucleus, within a cytoplasm.

IV. Nucleus

The nuclear envelope contains a double membrane with pores that surround the nucleus. Little things are allowed to get in while big things stay inside. DNA is attached to a protein found in the nucleus in the form of chromatin (uncondensed, not currently dividing).

46 chromosomes in humans

Nucleolus is found in the nucleus. Ribosome production occurs in the nucleolus.

Nucleolus --> Ribosomes --> Protein

There may be one or more nucleolus per nucleus.

V. Ribosomes

Ribosomes look like small dots in the cytoplasm and in the Rough Endoplasmic Reticulum (RER). Ribosomes assist in protein synthesis by making enzymes and proteins for an organism. Ribosomes are responsible for providing proteins/enzymes.

VI. Rough Endoplasmic Reticulum

RER’s look rough and grain-like due to ribosomes. They produce membranes and secretary proteins.

VII. Smooth Endoplasmic Reticulum

Lacks ribosomes

Functions –

Makes lipids (steroids and hormones)

Cells in the liver detoxify (take toxins out) drugs and other poisons inside the blood.

VIII. Golgi Apparatus

Also known as the “UPS truck”

Finishes, stores, and distributes chemical products of the cell.

Final products are disturbed to other organelles or out of the cell membrane.

IX. Lysosomes

Means breaking down the body

Breaks down proteins, fats, polysaccharides, and nucleic acids.

Fuses with food vacuoles for digestion.

Useful products of digestion leave the lysosome and nourish the cell.

Destroys harmful bacteria.

Recycles damaged organelles.

Lysosomal Storage Diseases –

Lysosomes become enlarged and interferes with other cellular functions.

Ex: Tay-Sachs disease – ravages the nervous system

· Lacks lipid digesting enzyme and nerve cells in the brain which accumulates excess lipid and results in functioning improperly.

X. Vacuoles

Sizes and functions:

Food vacuole

Contractile vacuole

Central vacuole in a plant

· Store organic nutrients

· Absorb water – cells expand

· Pigments in petals to attract insects

· Contain poisons to deter plant eating animals

XI. Chloroplasts

Organelles of plants and protists that perform photosynthesis.

Stroma – thick fluid inside inner membrane

Grana – located in stroma, network of membrane enclosed tubes and disks, solar power packs (traps the sun’s energy and convert is)

XII. Mitochondria

Site of cellular respiration

Takes chemical energy from sugars and converts it to ATP (for of energy our cells use).

Found in most eukaryotic cells

Outer membrane and inner membrane that has multiple folding called cristae.

XIII. Cytoskeleton

A network of fibers extending throughout the cytoplasm

Functions:

Skeleton for support and cell shape.

The muscles are used for movement, rearrangement of cytoskeleton can cause cell or parts of the cell to move.

3 types of fibers:

Microfilaments

Intermediate filaments

Microtubules
Next scribe - Sonali