Module 1: Intro to Cell Biology & Cell Theory

Question 1

Why is the cell the fundamental unit of life?

Answer 1

All organisms are made of either a single cell or a group of cells

Question 2

The 3 tenets to the cell theory

Answer 2

1. All living organisms are composed of one (unicellular) or more (multicellular) cells
2. Each cell is the structural and functional unit of life
3. Cells can arise only from pre existing cells

Question 3

Exceptions to the Cell Theory

Answer 3

Viruses
Viroid’s
Prions

They need other organisms to function

Question 4

Basic Properties of Cells

Answer 4

1. Highly Complex & Organized but enclosed by physical barrier (cell membrane, cytoplasm [all contents found inside cell membrane], cytosol [jelly like fluid, cytoplasm minus organelles])
2. Genetic program (Central Dogma, DNA to RNA to protein via transcription and translation)
3. Capable of producing more of themselves (duplicate genetic material before division)
4. Acquire and utilize energy (ex light to energy)
5. Carry out a variety of chemical reactions
6. Engage in numerous mechanical activities (material transported in and out of the cell)
7. Able to respond to stimuli (receptors, predators)
8. Capable of self regulation (if lots of water can change to deal with pressure)

Question 5

Prokaryotes

Answer 5

• Single cell organism that doesn’t have a nucleus or membrane bound organelles
• Rely primarily on cell wall and internal rigid protein for framework support
• Two domains
  – Bacteria
  — many have plasmids (DNA separate from main bacterial chromosomes) and have a cell wall surrounding the membrane
  – Archaea
  — Have isoprenoid (which are a type of protein in the cell membrane) cell membrane, often inhabit extreme environments

Question 6

Eukaryotes

Answer 6

• Have membrane bound nucleus
  – defining characteristic that stores chromosomes
• Organized by internal protein scaffolding AKA cytoskeleton (which can be remodeled quickly) and dynamic membranes (like endomembrane system)
• Includes:
  – Protists
  – Fungi
  – Plants
  – Animals

Question 7

Protists

Answer 7

• Diverse group
• mostly single cells, but some form colonies
• includes
  – algae, water molds, slime molds, protozoa

Question 8

Fungi

Answer 8

• Have cell wall with chitin (modified polysaccharide)
• includes yeast, rust, smut, mold, mushrooms, mildew
• heterotrophs (need organic molecules for carbon energy, which they absorb from environment)

Question 9

Plants

Answer 9

• multicellular
• have cell wall made of polysaccharide’s
• large water filled vacuoles, which contributes to turgor pressure ( allows plant to keep rigid form)
• have intercellular connections (plasmodesmata)
• autotrophs (produce own food, chloroplasts covert sun energy into chemical energy)

Question 10

Animals

Answer 10

• Multicellular
• No cell walls
• Heterotrophs (get energy from carbon and organic molecules)
• Distinct mode of early development

Question 11

Endomembrane System

Answer 11

• Its a network of internal membranes
• Includes:
  – Nuclear envelope (defines boundary of nucleus and contains inner and outer membrane with nuclear pores)
  – Endoplasmic reticulum (ER)
  — complex network of connected tubules and flattened sacs
  — RER, has ribosomes for protein synthesis
  — SER, lack ribosomes
  – Golgi apparatus
  — modifies proteins and lipids produced by ER
• sorts them and adds carbohydrates

Question 12

Cytoskeleton

Answer 12

• Provides internal support for the cells
• All euks have 2 elements
  – Microfilaments
  – Microtubules
• Animals have 3
  – Intermediate filaments

Question 13

Role of model organisms

Answer 13

• Model organisms are used in research because they are non-human species that we can use to understand biology for different things like:
  – DNA replication (E. coli)
  – cell cycle (yeast)
  – genetics (flies)
  – gene sequencing ( worm)
  – model mammal (mouse)