Cell Structure and Function Flashcards
Name the 5 processes / levels of organization characteristic of all living things
- Growth
- Reproduction
- Responsiveness
- Metabolism
- Cellular structure
Why aren’t viruses considered to be living organisms?
Although they have responsiveness, they cannot grow
Describe prokaryotes (3)
- Lack a nucleus
- Lack membrane bound organelles
- Include eubacteria and archaea
Describe eukaryotes (2)
- Have a membrane bound nucleus
- Have membrane bound organelles
What are some examples of eukaryotes? (5)
- Animal cells
- Algae cells
- Fungi cells
- Plant cells
- Protozoa cells
Differentiate between eubacteria and archaea
- Eubacteria - true bacteria
- Archaea - ancient bacteria
What is a glycocalyx?
A gelatinous sticky substance that surrounds the outside of the cell
What are glycocalyces usually composed of?
Polysaccharides or polypeptides (or both)
Describe capsules (2)
- Firmly attached to the cell surface
- Protect cells against phagocytosis
Describe slime layers (2)
- Loose and water-soluble
- Enable cells to adhere to each other and to environmental surfaces
What effect do glycocalyx have upon bacterial desiccation (drying out)?
Protect the cell from desiccation and increase the cell’s ability to cause disease
What effect do glycocalyces have upon bacterial pathogenicity?
Prevent the entry to pathogens into the cell
What are flagella?
Long extensions from the cell surface and glycocalyx that propel a cell through its environment
What function do flagella impart to the bacterium?
Responsible for cell motility
What are the 3 ‘parts’ of a bacterial flagellum?
- Hollow filament
- Hook
- Basal body
What powers flagellar rotation?
The flow of ions through the cytoplasmic membrane near the basal body
Differentiate between peritrichous and polar flagella
- Peritrichous flagella - flagella that cover the surface of the cell
- Polar flagella - only found at the ends
Describe the mode of locomotion in some bacteria
- Bacteria move with a series of runs and tumbles
- Both occur in response to stimuli
What are runs?
Cellular movements in a single direction
What are tumbles?
Abrupt changes in direction
Differentiate between chemotaxis and phototaxis
- Chemotaxis - flagella move the cell toward or away from chemical stimuli
- Phototaxis - flagella move the cell toward or away from light stimuli
Differentiate between ‘positive’ and ‘negative’ taxis
- Positive taxis - moving towards something
- Negative taxis - moving away from something
Describe fimbriae (4)
- Short and sticky
- Proteinaceous
- Non-motile
- Extensions of bacteria
What is the function of fimbriae?
Enable cells to adhere to each other and to environmental surfaces
Fimbriae serve an important function in ______
Biofilms
Roughly how many fimbriae are typically present on a bacterium?
Hundreds per cell
Describe pili (3)
- Hollow
- Non-motile
- Tubes of protein
What is the function of pili?
Connect some prokaryotic cells
Roughly how many pili are typically present on a bacterium?
1 - 2 per cell
How do flagella and fimbriae compare in terms of overall size or length?
Fimbriae are usually shorter than flagella
What are biofilms?
Slimy masses of bacteria adhering to a substrate and to one another by means of fimbriae and glycocalyces
What role do glycocalyces and fimbriae play in the formation of biofilms?
Prevent the cell from drying, allowing it to stick to surfaces
What is a conjugation pilus and what is its function? (2)
- A special type of fimbria
- Allows for DNA transfer between bacteria
What is conjugation?
Process in which pili join two bacterial cells and mediate the movement of DNA from one cell to another
Describe 2 different functions of the bacterial cell walls
- Provides structure (characteristic shapes)
- Provides protection from somatic forces
Differentiate between cocci and bacilli (coccus vs. bacillus)
- Cocci - spherical cells that may appear in various arrangements depending on the planes of cell division
- Bacilli - rod-shaped cells, typically appearing singly or in chains
Differentiate among the following bacterial arrangements:
- Streptococci
- Staphylococci
- Sarcinae
- Filaments
- Streptobacilli
- Streptococci - chains of cocci
- Staphylococci - clusters of cocci
- Sarcinae - cuboidal packets of cocci
- Filaments - single bacilli cells not separated
- Streptobacilli - chains of bacilli
