Cell Theory + Microscopy

Cell Theory

Cell theory states that…

1. all living things are composed of cells

   1. Every that was ever alive is made of cells

2. Cell are the smallest unit of life

   1. contain organelles

3. Cells only arise from pre-existing cells

   1. Mitosis

   2. All life evolved from simple ancestors

   3. meiosis generates gametes

Theory is different than colloquial use.

Theories are

• *well substantiated

• *explains the natural world

• *based on body of facts

• *repeatedly confirmed

• *through observation /experimentation - rigorous testing

Viruses are not alive because

• no cells

• no homeostasis

• don’t grow

• cant reproduce by themselves

• cannot perform independent metabolism

Life is a self sustaining chemical system capable of Darwinian evolution

Types of cells

All cells have

Trend: a prevailing tendency or generalization

Discrepancy: does not fit the trend, or atypical

Common Cellular Structures

• Plasma membrane

  • Separate exterior from interior, bilayer formed from phospholipids

  • allows homeostasis

• cytosol

  • cytosol vs cytoplasm

    • cytosol is fluid, essential to metabolism and dissolves solutes (made of water

    • cytoplasn is fluid plus anything contained within (organelles)

• Deoxyribonuleic Acids (DNA)

  • genetic code, needed for making news cells

  • needed for reproduction and evolution

• ribosomes (Synthesize proteins)

  • uses DNA to make proteins

  • prokaryotes have smaller 70s ribosomes

  • eukaryotes (us) have 80s ribosomes

Discrepancies to Cell Theory

Red blood cells (erythrocytes)

• transports oxygen

• no nucleus

• no mitochondria

• No DNA

• Baby blood cells have nucleus and stuff, lose them as they mature

Aseptate Fungal Hyphae

• tubal projections of multicellular fungi

• make network

• no individual cells

• continuous cytoplasm

• more than one nuclei

Skeletal Muscles

• During development, cells fuse

• multi-nucleis

• large cells

• cells fuse together when maturing

• Need lots of nuclei to make lots of proteins

Phloem Sieve Tubes

• specialized cells of phloem

  • transports sugars

• Lose nucleus/organelles during developments

  • more space to transport

• Companion cells on the outside of them to provide all the organelles

Microscopy

Microscopes make little things big by magnifying them.

Magnifying is how much bigger something looks compared to how it is.

Resolution is how clear something is.

Light microscopes

• cover less things

• are cheaper.

• They have worse resolution.

• easy to use

• see living and dead specimens in color

• cell movement can be observes

• max magnifications is ~1500x

• low resolution

• stuff is upside down and backwards

Methylene blue: dyes genetic material

flourescent dyes: absorb and reemit light, glow

immunoflorescence: use antibodies to bind to particular substances

electron microscopes

• 100,000 to 300,000x magnifying

• high resolution

• expensive

• cells must be killed

• no movement observed

• no color

• can’t use dyes

• take up lots of space

Freeze Fracturing: Samples rapidly frozen, causes them to split at weakest point and can determine cell membrane

Cyrogenic electron microscopy: uses liquid ethane to freeze one layer of protein, produce different patterns based on electron configuration and then computers generate a 3d image

Micrograph = image obtained from a microscope

1. Measure the scale bar

   1. 20 mm

2. Convert the measurement to scalebar units

   1. 1mm = 1000 micrometers (count the zeros in scientific notation)

   2. 20 mm = 20,000 micrometers

3. Take what you measured and divide it by what the scale bar says

   1. 20,000 micrometers/10 micrometers

   2. 2,000x (units cancel, add x)

Organelles

Prokaryotes (not membrane bound)

Cell wall: a rigid non-cellulose structure that surrounds cells

Cytosol: The gel-like fluid inside the cell membrane where metabolic reactions occure

Pili: Hair-like protein structures that allow cells to attach to things

Plasma membrane: Phospholipid bilayer that surrounds the cell and controls the movement of materials into and out of a cell

Nucleoid: A dense region of DNA in a prokaryotic cell

Ribosomes: Direct protein Synthesis

Flagella: Long, thin, whip-like structures that enable movement

Eukaryotes (membrane bound)

Flagella: Allows cell motility in unicellular eukaryotes (&prokaryotes)

Plasma Membrane: Phospholipid bilayer that surrounds the cell and controls the movement of materials into and out of a cell

Cytosol: Fluid within the plasma membrane where organelles are found

Free 80s Ribosomes: sythesize proteins for use inside the cell

Cell Wall: Supports and maintains the shape of plant cells

Nucleus: Surrounded by a double membrane with pores, it containes the cell;s DNa

Free Ribosomes: Sythesis of proteins for use in the cell

Golgi Aparatus: Stores, modifies, and packages proteins

Vacuoles & Vesicles: Single membrane sacs used for storage and transport (Vesicles are darker and carry proteins, vacuoles carry water and are clear)

Lysomes: Contain digestive enzymes, and can fuse with vesicles containing damaged organelles

Rough Endoplasmic Reticulum (rER) : Synthesis of proteins for use outside the cell

Chloroplast: Site of the formation of organic compounds via photosynthesis

Centrioles: Assemble microtubules for the spindle in mitosis

Mitochondrion: The site of aerobic respiration, produces ATP

Smooth Endoplasmic Reticulum (sER): Branched network of tubular membranes that synthesizes lipids, phospholipids, and steroids

Notes

DNA does not have histoids in prokaryotes

Nucleiod: Main DNA of the cell

Plasmid: Extra DNA

1. Small, circular

2. naked

3. Replicates ind. from nucleiod

4. not in all prokaryotes

5. can be shared

6. often contained antibiotic resistance genes

7. little rings floating around

Bacteria comes in three shapes

1. Rods (bacilli)

   1. Can form chains

2. Spheres (Cocci)

   1. Forms chains and clusters

3. Spirals (Spirochete)

   1. Hard to kill

   2. Bad news

Plants are autotrophs and multicellular (and weird)

Fungi can be unicellular (yeast) or multicellular (mushrooms)

Animals do not have cell walls, the most diverse

Animals and fungi don’t have plastids, plants do: chloroplasts and amyloplasts

Fungi plant walls are made of chitin, plants are made of cellulose

Animals have small temporary vacuoles, fungi and plants have large permanent vacuoles

Animals have centrioles to help in cell division, plants and fungi don’t (except ones with swimming male gametes)

Endulipodia are present in many animal cells (ex. sperm) , none in fungi and plants (except ones with swimming male gametes)