Microorganisms Flashcards
Label the bacterial structures
See notes for diagram
List the structures of a bacteria cell
- Pili
- Cell membrane
- Mesosome
- Capsule
- Cell wall
- Free floating DNA
- Flagellum
- Ribosomes
- Plasmid
What is the bacteria cell wall made up of?
Peptidoglycan
What is peptidoglycan?
A polysaccharide cross linked by peptide chains
What are ribosomes made up of?
RNA and protein
What is the function of the ribosomes?
Synthesis of protein from mRNA
What is the mesosome?
Infolding of the cell surface membrane
What is the mesosome caused by?
Cell damage in preparation for viewing under an electron microscope - an artefact
What is the capsule made up of?
Secreted slime and mucus
What are the functions of the capsule? - 3
- Protection from the immune system
- Protection from dehydration
- Allows bacteria to form colonies
What are plasmids?
Small double stranded loops of DNA
What can plasmids be used for?
They can be transferred between bacteria to exchange genes
What are pili?
Protein tubes
What can pili be used for? - 2
- Allowing bacteria to attach to other cells
- Used in gene transfer of plasmids
What is the plural of “flagellum”?
Flagella
What do flagella look like?
Long and hair like
What are flagella used for?
Cell movement
Where is the DNA found in bacteria?
Floating free in the cytoplasm
What does DNA look like in bacteria?
Coiled up in one long circular strand
What is the difference between DNA in bacteria - and other prokaryotic cells - and in eukaryotic cells?
- No nucleus/chromosomes
- DNA is not folded around proteins
Do all prokaryotic cells have a cell membrane?
Yes
Do all prokaryotic cells have pili?
No
Do all prokaryotic cells have flagella?
No
Do all prokaryotic cells have a cell wall?
Yes
Do all prokaryotic cells have free floating DNA?
Yes
Do all prokaryotic cells have plasmids?
Yes
Do all prokaryotic cells have a capsule?
No
Do all prokaryotic cells have ribosomes?
Yes
What is the difference between ribosomes in bacteria - and other prokaryotic cells - and in eukaryotic cells?
Much smaller in bacteria and other prokaryotic cells
How small are bacteria?
Only a few micrometers long
How do bacteria reproduce?
Asexually by binary fission
Basic description of a virus
Nucleic acids surrounded by a protein coat
What could the genetic material/nucleic acids of a virus be?
RNA/DNA
Viral DNA can be one of two things
Double stranded/single stranded
What size are viruses relative to bacteria?
Much smaller
What size is HIV?
0.1 micrometres
What word is used to describe a virus to show it is not a cell?
Acellular
Why are viruses non living?
- They don’t have their own cells
- Can’t reproduce without other living cells’ organelles
Are viruses living?
No
List the structures in a virus cell
- Genetic material
- Capsid
- Attachment proteins
- Proteins
- Envelope
Label the viral structures
See notes for diagram
What is a capsid?
Protein coat around the genetic material
What are attachment proteins?
Proteins joining the virus to its host cell
Where are the proteins in viruses?
In the capsid
Give an example of an extra protein in a virus?
Reverse transcriptase in HIV
What is a viral envelope?
An extra outer layer stolen from the cell membrane of a previous host cell
What structures do not all viruses have?
- Envelope
- Proteins
How do viruses reproduce?
Using the host cell’s organelles/machinery to replicate
Describe the steps of viral reproduction - 6
- Attachment proteins bind to complementary receptor proteins on the host
- Viruses insert nucleic acid
- Nucleic acids replicate
- Viral coats are synthesised
- New virus particles formed
- Virus particles released in cell lysis
How are attachment proteins specific to each host cell?
They are specific to their receptor proteins
Define “pathogen”
A microorganism causing disease
