Viruses

Question 1

Why can viruses be classed as living?

Answer 1

They are capable of reproducing, replicating their genetic info and hey can move, travel through the body and enter host cells

Question 2

Why can viruses be classed as non-living?

Answer 2

They cannot excrete, respire, grow and are not sensitive to their environment

Question 3

How do viruses replicate and cause illness?

Answer 3

They enter living organisms, attach to host cells by complementary receptor proteins on the host cell and attachment proteins on the viruses surface and inject their RNA (as don’t undergo cel division). RNA replicates inside the cell continuously until the cell is full and bursts. Copies are then free to invade other cells

Question 4

Why can some viruses only infect one type of cell?

Answer 4

Different viruses’ have different attachment proteins and so require different receptor proteins on host cells, some viruses can infect lots of different cells though

Question 5

What are the main differences between prokaryotic and eukaryotic cells?

Answer 5

Prokaryotic cells have a cell wall whereas eukaryotic cells don’t except for plants. The genetic material in prokaryotic cells is found free in the nucleus as plasmids and nucleoid so not associated with proteins whereas DNA in eukaryotic cells is found in the nucleolus in the form of chromosomes, associated with proteins called histones. Prokaryotic cells have smaller and fewer ribosomes than eukaryotic cells. Prokaryotic cells don’t have membrane bound organelles including ER, golgi apparatus and mitochondria whereas eukaryotic cells do. Prokaryotic cells have flagellum, plasmids and a slime capsule whereas eukaryotic cells don’t

Question 6

What is a virus?

Answer 6

An acellular, non-living pathogen - made of nucleic acids surrounded by proteins