Cell Structure and Division- Prokaryotic Cells and Viruses Flashcards
How are prokaryotic cells different from eukaryotic cells?
They are smaller and simpler
What is the cytoplasm of a prokaryotic cell?
Has no membrane-bound organelles and has ribosomes that are smaller than eukaryotic ribosomes
What is the plasma membrane in a prokaryotic cell?
Mainly made of lipids and proteins and controls the movement of substances into and out of the cell
What is the cell wall in a prokaryotic cell?
Supports the cell and prevents it from changing shape
What is the cell wall made from in a prokaryotic cell?
A polymer called murein which is a glycoprotein
What is a capsule?
An organelle that some prokaryotic cells have that is made up of secreted slime and helps to protect bacteria from attack by cells of the immune system
What are plasmids?
Small loops of DNA that aren’t part of the main circular DNA molecule
Why are plasmids important?
They contain genes for things like antibiotic resistance and can be passed between prokaryotes
How many plasmids do prokaryotes contain?
They are not always present or some have several
Does a prokaryotic cell have a nucleus?
No
What do prokaryotic cells have instead of a nucleus?
The DNA floats free in the cytoplasm, it is circular DNA which is one long coiled-up strand that is not attached to any histone proteins
What is the flagellum?
A long hair-like structure that rotates to make the prokaryotic cell move
Do all prokaryotic cells have a flagellum?
No, and some have more than one
What are viruses?
Acellular, they are nucleic acids surrounded by proteins that aren’t alive
What is the size of a virus?
Smaller than bacteria
How do viruses reproduce?
They invade and reproduce inside of the cells of other organisms known as a host cell
How are viruses different to bacteria?
They have no plasma membrane, no cytoplasm and no ribosomes
What is the structure of virus?
A core of genetic material (DNA or RNA), a protein coat around the core called the capsid, attachment proteins that stick out from the edge of the capsid that let the virus cling on to a suitable host cell
How do prokaryotic cells replicate?
Binary fission
What is binary fission?
The cell replicates its genetic material before physically splitting into two daughter cells
What is the first step of binary fission?
The circular DNA and plasmid(s) replicate- the main DNA loop is only replicated once but plasmids can be replicated many times
What is the second step of binary fission?
Cell gets bigger and DNA loops move to opposite poles of the cell
What is the third step of binary fission?
Cytoplasm begins to divide and new cell walls begin to form
What is the fourth and final step of binary fission?
Cytoplasm divides and two daughter cells are produced- each daughter cell has one copy of the circular DNA but can have a variable number of copies of the plasmids
How do viruses use their attachment proteins?
To bind to complementary receptor proteins on the surface of the host cell
Why can some viruses only infect one type of cell?
Different viruses have different attachment proteins so require different receptor proteins on host cells
Do viruses undergo cell division?
No because they’re not alive so instead they inject their DNA or RNA into the host cell which then uses its own ‘machinery’ to replicate the viral particles
