Ch 4 Prokaryotic Cells & Microorganisms Flashcards
What are some characteristics that all living things have on a cellular level?
- Basic Shape
- Internal content
- DNA Chromosomes
- Ribosomes
- Metabolic capabilities
What are two types of cells?
Eukaryotic & Prokaryotic
Eukaryotic
Cells that have a nucleus & membrane-bound organelles
Ex: animals, plants, fungi, & protists
Prokaryotic
Cells that lacks nucleus and membrane-bound organelles
Ex: bacteria & archaea
Characteristics of Life
- Reproduction & Heredity
- Growth & Development
- Metabolism
- Movement
- Cell support, protection, & storage
- Transport of nutrients & waste
Appendages Found in Prokaryotes
Flagella, Pili, and Axial Filaments
Define Flagellar Response & its purpose
- Def: Guides bacteria in a direction in response to external stimuli
- Stimuli signal sets the flagella into motion
- Counterclockwise: smooth linear direction
- Clockwise: tumbles
What is Fimbriae and its function?
- Fine hairlike bristles emerging from the surface of the cell
- Function: sticks onto cells and surfaces
What is Pili? Where is it found, and what is its purpose?
It is a rigid tubular structure made of pilin protein, found in gram-negative cells.
Function: joins bacterial cells for partial DNA transfer called conjugation
External Structure of Prokaryotes (Outer to inner layer)
The external function is known as Cell Envelope. It consists of…
1. Glycocalyx (surface coating)
2. Cell membrane
3. Cell wall
Functions of Glycocalyx
- Protecting cells from dehydration & nutrient loss
- Prevents killing by white blood cells
- Attachment: formation of biofilms
What is inside bacterial cells (prokaryotes)?
- Cytoplasm
- DNA chromosomes
- Ribosomes
- Plasmids
Cytoplasm
Dense gelatinous solution of sugars, amino acids, and salts
Serves as a solvent for materials used in all cell functions
Chromosome
Threadlike structure made up of nucleic acids that contains all the genetic information
Plasmids
Free small circular, double-stranded DNA
Not essential to bacterial growth and metabolism
Used in genetic engineering - readily manipulated and transferred from cell to cell
Ribosomes
Made up of RNA & Protein
Translates genetic code to amino acids to create protein polymers
Site of protein synthesis
Found in all cells
Bacterial Internal Structure
- Inclusions and granules
- Cytoskeleton
- Endospores
- Sporulation
- Germination
Inclusions and granules
Intracellular storage bodies
Vary in size, number, and content
Bacterial cells can use them when environmental sources are depleted
Cytoskeleton
An internal network of protein polymers that is closely associated with the cell wall
Endospores
Inert, resting, cells produced by some G+ genera: Clostridium, Bacillus, and Sporosarcina
Sporulation
It is the formation of endospores:
- most rigid compared to all life forms
- withstands extremes in heat, drying, freezing, radiation, and chemicals
- no reproduction
Germination
Returns to vegetative growth
